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Physico-chemical characterization of biochars from vacuum pyrolysis of South African agricultural wastes for application as soil amendments
Abstract
The physico-chemical properties of biochars from the vacuum pyrolysis of black wattle and vineyard
annual prunings were investigated for their potential as soil amendments and compared to biochar
from sugar cane bagasse. Biochar from sugar cane bagasse seems to be a promising sorbent and soil
conditioner due to its high surface area, high surface acidity and microporous structure. This biochar can
be applied to a wide pH range of soils for enhancing nutrient and water retention. On the other hand, the
biochars from black wattle and vineyard possessing high concentrations of aromatic carbon, nutrients,
and alkalinity are potential soil amendment agents. Black wattle biochar is more beneficial compared
to biochar from vineyard due to its higher surface area, microporosity and cation exchange capacity.
Therefore, this study recommends the utilization of biochars from black wattle as soil amendment agents
especially in subtropical regions.
... The O/C ratios of the biochars were in the range of 0.1 to 0.3 indicating their minimum half-life is around 1000 years (O/C < 0.2) [19]. H/C ratios were observed to be between 0.5 and 2 and are in agreement with those reported in literature for biochar pyrolysed from black wattle (0.54), vineyard pruning (0.59), and sugarcane bagasse (0.64) [20]. ...
... −1 ) and diameter (4-8 to 2.05-2.47 nm) were in agreement with literature values (Table 3) [20]. The low surface area could be due to the structural ordering, pore widening and/or coalescence of neighbouring pores during the pyrolysis. ...
... The surface acidity is apparently caused by the presence of carboxyl, lactones, and phenols (3412 cm −1 , and 1616 cm −1 peaks in Fig. 3), whereas the presence of carbonates may have contributed to the surface alkalinity (875 cm −1 and 803 cm −1 peaks in Fig. 3). Table 5 shows that alkaline functionalities of biochars are higher than their acidic functionalities, which is in agreement with biochar obtained from the pyrolysis of vineyard pruning, whereas the reverse has been observed in the case of black wattle and sugarcane bagasse biochar [20]; this indicates that the pyrolysis conditions as well as nature of feedstock have significant effect on the biochar surface functionality. The estimated surface functionalities were also supported by analysis of the IR spectra. ...
Biochar, a highly carbonaceous charred organic material obtained from biomass conversion can be deliberately applied as a conditioner/ amender in order to improve soil quality and associated environmental services. Napier grass (Pennisetum purpureum), a lignocellulosic biomass, can potentially be used to produce biochar. The aim of the present work is to manufacture, comprehensively characterize, and apply biochar obtained from the vacuum pyrolysis and investigate its potential for soil amendment. Biochar produced from Napier grass was characterized for its pH, electrical conductivity, soil water retention capacity, surface acidity and/or basicity, elemental composition, Infrared spectra, X-ray diffraction spectra, surface area, porosity, soil–water relation and morphological properties. Experiments on the methylene blue adsorption of the biochar indicated an equilibrium uptake capacity of 35 mg.g−1 and showed good agreement with the Langmuir–Freundlich model. Kinetic studies revealed Lagergren pseudo-first-order fit with intra-particle diffusion appearing to be one of the rate controlling mechanisms. Pot trials with Cicer grown in neutral and acidic soil amended with biochar validated that biochar augmented plant growth in terms of enhanced biomass weight and number of seed germinations. The entire investigation revealed that the properties of the produced biochar are in line with those necessary for it to act as a suitable agent for soil amendment.
... Previous studies have demonstrated that the feedstock and production conditions have a significant influence on biochar yield [9,13,21,22], physicochemical characteristics [23][24][25][26][27][28][29][30][31][32][33][34][35]; stability and mean resident time (MRT) [9,25,[36][37][38][39][40][41][42][43], total potential carbon (TPC) and CO 2 reduction potential [44][45][46], and energy properties [47][48][49][50][51][52]. Thus, detailed information about the complete production process and characterization is a key factor in defining the most appropriate application of biochar, for instance, as highly recalcitrant biochar may function as carbon fixation materials, whereas those rich in elemental compositions or those which have high porosity could be used as amendments to improve soil fertility [3] or those with a higher heating value (HHV) could be exploited to produce solid fuel in the form of briquettes [41] for industrial applications. ...
... Significantly higher CEC (43.0 cmol kg −1 ) in biochar was observed with 18.0 kg load kiln −1 at 350-400 • C, which supports the relationship between functional groups and biochar CEC [29,32]. The presence of negatively charged functional groups on the biochar surface gives biochar its ability to attract, retain and exchange basic cations [28]. Low CEC values of the biochar produced at the higher temperature of 450-500 • C do not seem to have strong nutrient retention potential if applied fresh in soil. ...
... The biochar C/N ratios ranged between 44.5 and 65.8 and were found to decrease with increasing temperature [31]. Gener-Sustainability 2022, 14, 2295 9 of 16 ally, higher C/N ratios are reported to result in inorganic N immobilization by microbes which induce N unavailability for plants [28]. Even though our results suggest wider C/N ratios, the recalcitrance nature of biochar may resist microbial decay to an extent suggesting that biochar as a soil amendment has little influence on soil N immobilization [65]. ...
Citation: Venkatesh, G.; Gopinath, K.A.; Reddy, K.S.; Reddy, B.S.; Prabhakar, M.; Srinivasarao, C.; Visha Kumari, V.; Singh, V.K.
... Previous studies have demonstrated that the feedstock and production conditions have a significant influence on biochar yield [9,13,21,22], physicochemical characteristics [23][24][25][26][27][28][29][30][31][32][33][34][35]; stability and mean resident time (MRT) [9,25,[36][37][38][39][40][41][42][43], total potential carbon (TPC) and CO 2 reduction potential [44][45][46], and energy properties [47][48][49][50][51][52]. Thus, detailed information about the complete production process and characterization is a key factor in defining the most appropriate application of biochar, for instance, as highly recalcitrant biochar may function as carbon fixation materials, whereas those rich in elemental compositions or those which have high porosity could be used as amendments to improve soil fertility [3] or those with a higher heating value (HHV) could be exploited to produce solid fuel in the form of briquettes [41] for industrial applications. ...
... Significantly higher CEC (43.0 cmol kg −1 ) in biochar was observed with 18.0 kg load kiln −1 at 350-400 • C, which supports the relationship between functional groups and biochar CEC [29,32]. The presence of negatively charged functional groups on the biochar surface gives biochar its ability to attract, retain and exchange basic cations [28]. Low CEC values of the biochar produced at the higher temperature of 450-500 • C do not seem to have strong nutrient retention potential if applied fresh in soil. ...
... The biochar C/N ratios ranged between 44.5 and 65.8 and were found to decrease with increasing temperature [31]. Gener-Sustainability 2022, 14, 2295 9 of 16 ally, higher C/N ratios are reported to result in inorganic N immobilization by microbes which induce N unavailability for plants [28]. Even though our results suggest wider C/N ratios, the recalcitrance nature of biochar may resist microbial decay to an extent suggesting that biochar as a soil amendment has little influence on soil N immobilization [65]. ...
The crop residues generated in agricultural fields are mostly considered a burden due to their disposal issues. This study attempts to effectively use pigeon pea stalk (PPS) for biochar production, a promising source as a soil amendment for carbon sequestration and alternative fuel source. PPS was pyrolyzed at different loads and reaction times to optimize the kiln temperature (350–400 °C and 450–500 °C) and changes in physicochemical properties, higher heating value (HHV) and yield were assessed. The results indicated that biochar yield, volatile matter, bulk density, O/C and H/C atomic ratios decreased, whereas fixed carbon, ash content and total porosity increased with increasing kiln temperature across all loads. Biochar produced at 450–500 °C (18 kg load kiln−1) had higher total carbon, nitrogen, phosphorous, recovered total carbon and total nitrogen, total potential carbon and CO2 reduction potential. Biochar produced at 350–400 °C had the maximum cation exchange capability (43.0 cmol kg−1). Biochar has estimated O/C and H/C atomic ratios of 0.07–0.15 and 0.35–0.50, respectively. Biochar exhibited good agronomic characteristics and fulfilled key quality criteria of H/C < 0.7 and O/C < 0.4 for soil carbon sequestration, as described by the European Biochar Certificate and the International Biochar Initiative. The estimated mean residence time and the mass fraction of carbon that would remain after 100 years were consistently greater than 1000 years and 80%, respectively. The biochar produced at 450–500 °C (at 18.0 kg kiln−1) from PPS had higher fixed carbon (65.3%), energy density (1.51), energetic retention efficiency (53%), fuel ratio (4.88), and HHV (25.01 MJ kg−1), as well as lower H/C and O/C ratios, implying that it is suitable for use as an alternative solid fuel.
... It was reported that the pH values increased as the carbonization temperature and residence time increased [17,61]. A similar trend was observed in this study. ...
... Rights reserved. acidic as formic, acetic, and propionic acids and water were formed in the biochar once degradation of hemicellulose took place around 300 °C [17,61]. The biochar exhibited a more oxygenated and labile C with the presence of acidic functional groups and caused it to have a lower pH value [57]. ...
... As the pyrolytic temperature rose from 400 to 500 °C, the acidic functional groups (i.e., alcohol) were deprotonated to the conjugate bases and non-metal oxides with low melting points turned into ashes and assisted in the production of biochar with high pH value [17,57,61]. The presence of high melting point of metal oxides in biochar and the removal of non-metal oxides also contributed to the base nature of biochar [43]. ...
The relationship between physicochemical and morphology properties of biochar derived from oil palm trunk (BOPT) as a potential candidate in the production of high-performance activated carbon was intensively investigated. The biochar was prepared using various pyrolysis temperature and pyrolysis time to study the relationship of both parameters on the production of quality biochar. The proximate and ultimate analyses showed that the biochar with the highest fixed C and C contents can be acquired when the oil palm trunk was pyrolyzed at 450 °C for 3 h. The field emission scanning electron microscope images display the formation of pores in the biochar, whereas thermogravimetry analysis reveals the thermal stability of the biochar where both analyses are seemed to be in an agreement with other analyses and regarded the biochar as a potential candidate to be served as a promising precursor with a well-developed carbon framework. Overall, the BOPT-450–3 was found to exhibit 75.84% of C, 64.34% of fixed C, a ratio of H/C of 0.035, and 0.2733 m²/g (SBET). This study demonstrated that BOPT-450–3 is a good-quality biochar that has great attributes to be selected as a promising AC precursor for future directions.
Graphical abstract
... Higher values of hydrocarbons and organic carbons indicate a relatively high content of aliphatic and oxidized substances, while lower values suggest a relatively higher content of aromatic and reduced substances (Hass and Lima, 2018). SCB biochar with high aliphatic carbon content and low aromatic carbon content is less appealing as a carbon sequestering agent because it degrades quickly in soil (Uras et al., 2012). Table 4 also includes the BET surface areas of the biochars. ...
... Table 4 also includes the BET surface areas of the biochars. The surface area represents the physical development that occurs during the thermochemical conversion of biomass to biochar and is connected to the sorption ability of biochar (Uras et al., 2012). ...
Sugarcane bagasse (SCB) is the fibrous lignocellulosic residue left over after crushing sugarcane to extract juice for sugar and ethanol production. In this review, a concise overview of existing thermochemical technologies for the production of biochar from SCB and its potential applications is presented and discussed. Some of the technologies used so far in this regard include pyrolysis, gasification, hydrothermal carbonization, and torre-faction. However, pyrolysis was found to be the most widely used among them. These processes can be affected by several operating conditions such as temperature, heating rate, particle size, and residence duration, with temperature being the most significant and efficient variable influencing the quality of the biochar. The yield of SCB biochar reported in the literature ranged from 14 % to 56 %. A higher yield of biochar can be obtained at a lower temperature than at a higher one because biochar decomposes at higher temperatures (>500 • C). SCB biochar has promising applications in agriculture and the environment, including soil amendment, adsorbent in water and wastewater treatment, supplementary cementitious material, amongst others. Some knowledge gaps were also stated in the study, such as the cost analysis and comparison of utilizing bagasse as fuel in sugar industries and for the production of biochar. Sugarcane bagasse biochar has the potential to become a highly promising carbon material with a wide range of applications in a variety of sectors.
... The analysis in Table 2 presents the surface area, pore diameter, and pore volume results for bamboo biomass, biochar, and activated biochar. Biochar has gained attention in adsorbent materials due to its remarkable features such as high 34 Fig. 2 Mass yield for raw bamboo biomass at different pyrolysis temperatures stability, significant surface area, and ability to effectively remove contaminants, thanks to its highly porous structure [29]. Biochar and activated biochar are considered the most effective adsorbents in water and air purification treatments, having a strong affinity towards harmful gases due to their increased surface area and porosity, which retain contaminants inside their pores [30]. ...
... Compared to other agricultural waste biomass, biochar from bamboo biomass had significantly higher BET surface areas, ranging from 85 to 338 m 2 /g [32]. The vacuum production process accelerates devolatilization, which reduces product partial pressure and gas retention time, resulting in large surface areas in biochar produced by vacuum pyrolysis due to the opening of pores throughout the process [34]. Furthermore, as the temperature of pyrolysis increases, pore-blocking inside the structure is forced out or thermally broken, this also increases the surface area of the biochar. ...
This study aimed to use activated biochar made from bamboo (B) to adsorb CO2 and PM2.5. Raw bamboo biomass had a yield of 34.25% biochar at 500 °C with a residence time of 60–120 min. Activated biochar was produced by treating the biochar with the chemical KOH (Potassium Hydroxide), resulting in a BET surface area of 338 m2/g. SEM analysis showed that biochar and activated biochar had a highly porous structure, making them effective at extracting organic and inorganic contaminants from the air. The sorption capacity of bamboo-activated biochar for air was assessed, and the results showed that the bamboo-activated biochar produced at 700 °C had superior physicochemical composition. When using activated bamboo biochar, the air purifier's performance efficiency for removing CO2 and PM2.5 was 91.23 and 89.19%, respectively.
... However, other factors may contribute to surface area. Uras et al. (2012) found sugarcane bagasse biochar exhibited a surface area of 259 m 2 g −1 when produced at 475˚C. The high moisture content of the bulk biochar is likely an artifact of its prolonged exposure to precipitation while stored in plastic superbags prior to its collection. ...
... Domingues et al. (2017) reported that the %C of sugarcane bagasse-derived biochar increased with pyrolysis temperature, with values of 74.7% (350˚C), 81.6% (450˚C), and 90.5% (750˚C). Uras et al. (2012) found 57.3% C in sugarcane bagasse-derived biochar pyrolyzed at 475˚C. The greatest mass loss below 300˚C was found to be associated with hemicellulose, where 40% by weight was volatilized between 220˚C and 315˚C; over 80% of pure cellulose decomposed primarily between 315˚C and 400˚C; lignin decomposed more gradually but remained >50% even at 800˚C (Yang et al., 2007). ...
Sugarcane (Saccharum spp.) represents the most valuable row crop in Louisiana. High levels of biomass production and extensive tillage have degraded portions of the state's alluvial soils used to grow sugarcane. In addition to sucrose, processing the crop generates excess bagasse each year, which can represent a disposal problem for sugar factories. However, converting the bagasse to biochar at nearby pyrolysis facilities may prove to be an economical means of improving degraded soils. The objective was to determine the impacts of low rates of biochar (<3.2 mt ha⁻¹) on soil physical, chemical, and biological properties. Plant available nutrient levels were marginally impacted by biochar additions as the biochar exhibited a relatively low surface area and neutral pH. Bagasse‐derived biochar did not affect soil nitrate retention or leaching, and overall recovery was >86%. Biochar did not increase soil CO2 evolution, indicating its stability as a soil carbon amendment. However, adding biochar with mineral nitrogen decreased CO2 evolution, compared to biochar alone, indicating a negative priming effect. Soil moisture retention was minimally impacted by biochar. Cane yield, sucrose content, and sucrose yield were not statistically affected by applying biochar with or without starter fertilizer at planting. Overall, the results indicate that lower levels of bagasse‐derived biochar minimally impacted soil properties and crop yield; however, the biochar was stable in soil and may find utility as a carbon‐rich amendment should carbon credits prove to be an additional source of grower or land‐owner revenue.
... The feedstock presented peaks at 3417 cm −1 that correspond to the alcohol/phenolic O-H stretching, which is supposed to be 3200-3550 cm −1 [32]. Additionally, the results presented peaks at 2918, 2848, 1625, and 1052 corresponding to asymmetric C-H stretching, symmetric C-H stretching, aromatic C=C carbon stretching, and C-O stretching of alcohol [33][34][35][36]. Upon gasification, the absorbance of the O-H stretching at 3417 cm −1 increased. ...
... These peaks correspond to carboxylic acid stretching vibration [37]. The gasification of wild sugarcane also increased the absorbance of aliphatic CH3 deformation, which presented at 1380 cm −1 [36]. P-O stretching peaks appeared after gasification at 1116 cm −1 [38]. ...
Wild sugarcane (Saccharum spontaneum L.) is an invasive plant species in the Central American region. Due to its low nutrient and water requirements, it can grow fast and displace native species. Therefore, its biomass is considered a waste to prevent the further distribution of the specie. This study investigates the production and characterization of wild sugarcane biochar to provide a use for its waste. The produced biochar was used for atrazine adsorption in aqueous solutions to provide a possible application of this biochar near the water bodies that were often detected to be contaminated with atrazine. The biochar was produced via top-lit updraft gasification with airflow rates between 8 to 20 L/min, achieving yields ranging from 22.9 to 27.5%. Batch experiments revealed that biochar made at 12 L/min presented the best removal efficiency (37.71–100%) and the maximum adsorption capacity (qm = 0.42 mg/g). Langmuir (R2 = 0.94–0.96) and Freundlich (R2 = 0.89–0.97) described the experimental data appropriately. Fourier transform infrared spectroscopy suggested that atrazine removal in wild sugarcane biochar could be mainly due to carboxylic functional groups. In addition, the biochar organic carbon composition contributed to a higher removal capacity in biochar produced at different airflow rates.
... Higher values of hydrocarbons and organic carbons indicate a relatively high content of aliphatic and oxidized substances, while lower values suggest a relatively higher content of aromatic and reduced substances [122]. SCB biochar with high aliphatic carbon content and low aromatic carbon content is less appealing as a carbon sequestering agent because it degrades quickly in soil [127]. Table 4 also includes the BET surface areas of the biochars. ...
... The surface area represents the physical development that occurs during the thermochemical conversion of biomass to biochar and is connected to the sorption ability of biochar [127]. ...
Sugarcane bagasse (SCB) is the fibrous lignocellulosic residue left over after crushing sugarcane to extract juice for sugar and ethanol production. In this review, a concise overview of existing thermochemical technologies for the production of biochar from SCB and its potential applications is presented and discussed. Some of the technologies used so far in this regard include pyrolysis, gasification, hydrothermal carbonization, and torrefaction. However, pyrolysis was found to be the most widely used among them. These processes can be affected by several operating conditions such as temperature, heating rate, particle size, and residence duration, with temperature being the most significant and efficient variable influencing the quality of the biochar. The yield of SCB biochar reported in the literature ranged from 14% to 56%. A higher yield of biochar can be obtained at a lower temperature than at a higher one because biochar decomposes at higher temperatures (>500 °C). SCB biochar has promising applications in agriculture and the environment, including soil amendment, adsorbent in water and wastewater treatment, supplementary cementitious material, amongst others. Some knowledge gaps were also stated in the study, such as the cost analysis and comparison of utilizing bagasse as fuel in sugar industries and for the production of biochar. Sugarcane bagasse biochar has the potential to become a highly promising carbon material with a wide range of applications in a variety of sectors.
... The BET-SSA values of the non-amended soils were consistent with ranges of specific surface areas for soils belonging to different textural classes [51] and showed a satisfactory agreement with the BET-SSA values reported by Leao and Tuller [56] for soils with different textures. The BET-SSA obtained for the sole BC was equal to 280.7 m 2 /g, agreed with that reported by Uras et al. [57] for one of their considered BC, and was close to that (244.0 m 2 /g) measured by Ajayi and Horn [58]. The SSA obtained by the BET analysis can be considered reliable, because the technique seems capable of yielding sensible estimates of SSA when applied to nitrogen sorption by systems in which there are few micropores, i.e., <0.002 um [59]. ...
... BC did not improve the aggregate stability condition, but increased the amount of PAW, expressed in terms of volumetric field capacity and wilting point. The measured surface area, BET-SSA, was increased by BC application, with more evident effects in the loamy sand and in the loam than in the clay [57]. A tendency of the measured BET-SSA values to increase at increasing PAW was found. ...
There are significant regional differences in the perception of the problems posed by global warming, water/food availability and waste treatment recycling procedures. The study illustrates the effect of application of a biochar (BC) from forest biomass waste, at a selected application rate, on water retention, plant available water (PAW), and structural properties of differently standard textured soils, classified as loamy sand, loam and clay. The results showed that soil water retention, PAW, and aggregate stability were significantly improved by BC application in the loamy sand, confirming that application of BC to this soil was certainly beneficial and increased the amount of macropores, storage pores and residual pores. In the loam, BC partially improved water retention, increasing macroporosity, but decreased the amount of micropores and improved aggregate stability and did not significantly increase the amount of PAW. In the clay, the amount of PAW was increased by BC, but water retention and aggregate stability were not improved by BC amendment. Results of the BET analysis indicated that the specific surface area (BET-SSA) increased in the three soils after BC application, showing a tendency of the BET-SSA to increase at increasing PAW. The results obtained indicated that the effects of BC application on the physical and structural properties of the three considered soils were different depending on the different soil textures with a BET-SSA increase of 950%, 489%, 156% for loamy sand, loam and clay soil respectively. The importance of analysing the effects of BC on soil water retention and PAW in terms of volumetric water contents, and not only in terms of gravimetric values, was also evidenced.
... Alkali salts such as carbonates, oxides, and hydroxides of Ca, Mg, Na, and K, together with nutrients such as P, S, N, Fe, and Zn, released upon separation of mineral matter from the organic matrix, constitute the mineral ash content of biochar (Fungai and Sanjai, 2016). Hence, the mineral ash content of biochar is closely correlated with pH, EC, and nutrient status (Lehmann et al., 2011;Uras et al., 2012;Fungai and Sanjai, 2016). The high concentrations of Ca, Mg, and K observed in the present study and the presence of carbonate ions revealed by FT-IR may account for the high pH of the biochar and suggest that the biochar could be used as a liming material in acidic soils (Eduah et al., 2019;Frimpong-Manso et al., 2019). ...
Farmers in resource-poor areas of the Guinea Savanna zone of Ghana often face declining soil fertility due to the continuous removal of nutrient-rich harvested produce from their fields. This study focuses on the Lawra Municipality in the Guinea Savanna zone of Ghana, where low soil fertility, specifically, limits phosphorus (P) bioavailability and hinders crop production. The objective of this research is to formulate P-enhanced biochar-compost from maize stover (MS) and groundnut husk, which abound in the area, to close the nutrient loop. MS was co-composted with groundnut husk biochar at varying rates of 0, 10, 20, 30, and 40% by volume. To facilitate decomposition using the windrow system, the composting heaps were inoculated with decomposing cow dung, and the moisture content was kept at 60% throughout the monitoring period. The addition of biochar shortened the lag phase of composting. However, rates above 20% resulted in reduced degradation of MS. Biochar incorporation enriched the available phosphorus content in the final compost from 286.7 mg kg⁻¹ in the non-biochar-compost to 320, 370, 546, and 840.0 mg kg⁻¹ in the 10, 20, 30, and 40% biochar-compost, respectively.
... Accordingly, adding biochar to soil significantly increases soil fertility, boosts plant growth [3], and improves crop yield in acid and nutrient-deficient soils [13]. However, the soil amendment qualities of biochar are partly determined by the distinct physicochemical characteristics of biochar [14]. ...
Temperature greatly determines biochar’s physicochemical characteristics during the pyrolysis of a biowaste. This study aimed to investigate how pyrolysis temperature alters the physicochemical characteristics of water hyacinth (WH) biochar as a soil amendment. WH biomass was slowly pyrolyzed at three temperatures (350, 550, and 750 °C) for 2 h. Results show that biochar yield lessened from 51.0 to 33.3% with a temperature rise. When pyrolysis temperature increased biochar’s pH (9.24–11.2), electrical conductivity (28.0–44.7 mS cm⁻¹), liming capacity (17.7–33.0% CaCO3 equivalence), ash content (33.3–52.4%), available nutrients (Ca, Mg, K, P), surface area (1.1–29.8 m² g⁻¹), pore volume, C/N ratio (15.9–20.3), and water holding capacity increased. However, C, H, N, H/C (0.89–0.11) and O/C (0.62–0.49) ratios, cation exchange capacity (CEC) (44.4–2.3 cmol+kg⁻¹), and pore width decreased. Surface functional groups shrank when pyrolysis temperature increased. As the temperature rises, WH biochar becomes structured, porous, and recalcitrant. All WH biochar samples show high alkalinity, particularly developed at 550 °C and 750 °C could replace liming materials in soil acidity alleviation. Biochar produced at 350 °C and 550 °C could improve agricultural soil fertility and nutrient retention capacity due to the lower C/N ratio, high N content, and CEC. Biochar produced at 550°C and 750 °C can sequester carbon in the soil. Biochar developed at 750 °C be applied to amend soil physical properties due to its comparably high surface area and porosity. Hence, the thermal conversion of WH biowaste to biochar helps obtain suitable biochar properties for soil amendment.
... Previous research has emphasized the influential role of feedstock and production conditions in determining various aspects of biochar, including its yield [29,30], stability [2,[29][30][31][32][33][34][35][36][37], energy properties [38][39][40][41][42][43], total potential carbon (TPC), physicochemical properties [44][45][46][47][48][49][50][51][52][53][54][55][56], and CO 2 reduction potential [31,57,58]. Therefore, gaining a comprehensive understanding of the entire biochar production process and conducting thorough characterization is crucial for identifying the most suitable applications for biochar. ...
: The disposal of crop residues from agricultural fields is often seen as a burden due to the
difficulties involved. However, this study aims to turn pigeonpea stalks into biochar, which can
serve as a fuel substitute and soil amendment to sequester carbon. Different pyrolysis methods were
employed to investigate the variations in yield, physicochemical characteristics, and higher heating
value (HHV) of biochar produced from pigeonpea stalks. The biochar produced using a muffle
furnace exhibited higher fixed carbon and ash content. These characteristics make it beneficial for
restoring degraded agricultural soils by enhancing carbon sequestration. In addition, the muffle
furnace biochar demonstrated a total potential carbon ranging from 262.8 to 264.3 g of carbon per
kilogram of biochar, along with a CO2 reduction potential ranging from 77.17 to 79.68 CO2 eq
per kg. Both the European Biochar Certificate and the International Biochar Initiative confirmed
the agronomic abilities of the biochar and its compliance with the highest quality standards for
soil carbon sequestration, with 0.11 H/C and 0.7 O/C ratios. Furthermore, biochar produced by
muffle furnace from pigeonpea stalks exhibited superior fixed carbon recovery efficiency (181.66 to
184.62%), densification (5.86 to 6.83%), energy density (1.77 to 2.06%), energy retention efficiency
(54.80 to 56.64%), fuel ratio (18.95 to 22.38%), and HHV (30.66 to 32.56 MJ kg−1
). Additionally, it
had lower H/C and O/C ratios, suggesting its potential as an alternative solid fuel. The results
of the characterization of biochar with scanning electron microscopy (SEM) and Fourier transform
infrared spectroscopy (FTIR) revealed that the biochar samples prepared with both the methods had
carbonyl (C=O), C=C, and aromatic C-H functional groups; however, the biochar prepared in the
muffle furnace had more porosity. In summary, this study highlights the potential of using pigeonpea
stalks to produce biochar, which can be utilized as a renewable fuel substitute and soil amendment to
sequester carbon. The biochar derived from the muffle furnace exhibited desirable physicochemical
characteristics, high carbon content, and excellent energy properties, making it a promising option
for various applications.
... Vacuum pyrolysis is a variation of pyrolysis that applies the reduced pressure to minimize oxidation and maximize the yield of valuable products such as biochar, bio-oil, and biogas [147]. The low-pressure environment helps preserve the quality of the end products and increases the energy efficiency of the process. ...
... To mitigate the detrimental impacts of land intensification, researchers are investigating several protective agricultural practices (Liu et al., 2023), and the application of biochar as a soil conditioner stands out as one of the sustainable, environmentally friendly, and green techniques (Dwibedi et al., 2023). While there is some disagreement on the short-term (fresh biochar) and long-term (aged biochar) effects of biochar on soil quality, it is evident that biochar significantly influences soil quality (Uras et al., 2012). This Fig. 7 Mapping knowledge domain of a co-authoring and b corresponding-authoring countries in aging biochar-associated research study's data analysis focused on multiple aspects: (1) production and aging of biochar with biotic (microorganisms and organic molecules) and abiotic factors (freeze-thaw, temperature, moisture, chemical activation, etc.); (2) application of aging biochar for agro-environmental sustainability, encompassing climate change mitigation (carbon sequestration in soil), enhancement of nutrient pools in soil (mostly nitrogen, phosphorus, and potassium), and remediation of contaminated soil; (3) characterization of pristine and aging biochar; (4) mechanisms involved in climate change mitigation and soil pollution remediation; and (5) the primary research trend and hotspot in aging biochar research, focusing on overall crop production. ...
The copious amounts of data generated through publications play a pivotal role in advancing Science, Technology, and Policy. Additionally, they provide valuable and detailed information on research topics, emerging thematic trends, and criti- cal issues that demand increased focus and attention. Over the last few decades, biochar has produced an extensive body of high-quality papers and played a crucial part in achieving the long-term Sustainable Development Goals of the 2030 agenda of the United Nations about “Climate Change,” “Sustainable Agriculture,” “Environmental Sustainability,” “Zero Hunger,” “Human Wellbeing,” and “Circular Bioeconomy”. However, most of the research is on biochar that has been modified or functionalized using various chemical reagents or catalysts and reported widely in peer-reviewed, high-quality journals. No prior work analyzed the bibliometric data on aging biochar with (a)biotic processes. This study presents an innovative data- driven bibliometric analysis technique and paradigm for extracting the essence of the available peer-reviewed literature data to offer new perspectives on the research opportunities and potential of aged biochar for agro-environmental applications. The bibliometric data analysis indicates that aging biochar research for agro-environmental applications received attention, advanced, and resulted in 165 high-quality publications in reputed journals between 2011 and 2023. However, it is evident that there is still a considerable need for further attention in this area. The identification of the research trends/frontiers shows that biochar production effectively employs various biomass resources, aging with different (a)biotic factors, characterization, effects on global climate change, long-term carbon sequestration in soil, soil nutrient dynamics, restoration of multi-polluted soils and sediments, and plant growth all require continuous attention both now and in the future.
... The biomass gas can be used as a gaseous fuel for power generation and the liquid fraction can be used as biofuel after upgrading [4,5]. The biochar can be applied as soil amendment with the main component of carbon and inorganic materials [6,7]. Biomass includes agricultural residues and forest residues; as the world's major agricultural country, the crop-straw output reaches about 910 million tons in China per year, among which the wheat-straw production reaches about 300 million tons. ...
To realize the energy recovery of wheat straw, the pyrolysis behavior of wheat straw was studied at three heating rates (10, 20, and 30 K/min) based on thermogravimetric analysis (TG–DTG). Kinetics and thermodynamics were analyzed using Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) model-free methods, and the reaction mechanism was determined using the Coats–Redfern (CR) model-fitting method. The results show that there are three weightlessness stages in the pyrolysis process, of which the second stage was the main weightlessness stage and two distinct peaks of weightlessness were observed in this stage. With increasing heating rate, the main pyrolytic weightlessness peaks of the DTG curve shift to the high-temperature side. The pyrolysis activation energies calculated by the FWO and KAS methods are 165.17–440.02 kJ/mol and 163.72–452.07 kJ/mol, and the pre-exponential factors vary in the range of 2.58 × 1012–7.45 × 1036 s−1 and 1.91 × 1012–8.66 × 1037 s−1, respectively. The thermodynamic parameters indicate that wheat straw has favorable conditions for product formation and it is a promising feedstock. Its pyrolysis reaction was nonspontaneous and the energy output is stable. CR method analysis shows that the A1/3 random nucleation model is the most suitable mechanism to characterize the pyrolysis process and random nucleation may be in charge of the main pyrolysis stage. This study can provide a theoretical basis for the thermochemical conversion and utilization of wheat straw.
... Non-wood-derived biochars also have a higher cation exchange capacity (CEC): for example, Gaskin et al. (2008) reported a CEC almost five times higher for biochars produced from poultry litter (38 cmol⋅kg − 1 ) than for biochars produced from pine chips (5 cmol⋅kg − 1 ), under the same pyrolysis conditions. The application of biochar with a high CEC may enhance soil fertility by reversibly adsorbing cations and reducing nutrient loss through leaching (Uras et al., 2012;Yang et al., 2015). ...
Changes in soil microbial communities may impact soil fertility and stability because microbial communities are key to soil functioning by supporting soil ecological quality and agricultural production. The effects of soil amendment with biochar on soil microbial communities are widely documented but studies highlighted a high degree of variability in their responses following biochar application. The multiple conditions under which they were conducted (experimental designs, application rates, soil types, biochar properties) make it difficult to identify general trends. This supports the need to better determine the conditions of biochar production and application that promote soil microbial communities. In this context, we performed the first ever meta-analysis of the biochar effects on soil microbial biomass and diversity (prokaryotes and fungi) based on high-throughput sequencing data. The majority of the 181 selected publications were conducted in China and evaluated the short-term impact (<3 months) of biochar. We demonstrated that a large panel of variables corresponding to biochar properties, soil characteristics, farming practices or experimental conditions, can affect the effects of biochar on soil microbial characteristics. Using a variance partitioning approach, we showed that responses of soil microbial biomass and prokaryotic diversity were highly dependent on biochar properties. They were influenced by pyrolysis temperature, biochar pH, application rate and feedstock type, as wood-derived biochars have particular physico-chemical properties (high C:N ratio, low nutrient content, large pores size) compared to non-wood-derived biochars. Fungal community data was more heterogenous and scarcer than prokaryote data (30 publications). Fungal diversity indices were rather dependent on soil properties: they were higher in medium-textured soils, with low pH but high soil organic carbon. Altogether, this meta-analysis illustrates the need for long-term field studies in European agricultural context for documenting responses of soil microbial communities to biochar application under diverse conditions combining biochar types, soil properties and conditions of use.
... The biomass gas can be used as a gaseous biofuel for power generation, and the liquid fraction can be used as biofuel after upgrading [4,5]. The biochar is mostly composed of carbon and inorganic materials, which can be applied as soil amendment [6,7]. Biomass includes agricultural residues and forest residues, as the world's major agricultural country, the crop straw output reaches about 910 million tons in China per year, among which the wheat straw production reaches about 300 million tons. ...
To realize the energy recovery of wheat straw, the pyrolysis behavior of wheat straw was studied at three heating rates (10, 20, and 30 K/min) based on thermogravimetric analysis (TG–DTG). Kinetics and thermodynamics were analyzed using Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) model-free methods, and reaction mechanism was determined using Coats–Redfern (CR) model-fitting method. The results show that there are three weightlessness stages in the pyrolysis process, of which the second stage was the main weightlessness stage and two distinct peaks of weightlessness were observed in this stage. With increasing heating rate, the main pyrolytic weightlessness peaks of DTG curve shifts to higher temperature. The pyrolysis activation energy calculated by FWO and KAS methods are 165.17–440.02 kJ/mol and 163.72–452.07 kJ/mol, and the pre-exponential factor vary in the range of 2.58×1012–7.45×1036 s-1 and 1.91×1012–8.66×1037 s-1, respectively. The thermodynamic parameters indicates that wheat straw has the favorable conditions for product formation and containes potential energy to be utilized for bioenergy production, its pyrolysis reaction was non-spontaneous and the energy output is stable. CR method analysis shows that the A1/3 random nucleation model is the most suitable mechanism to characterize the pyrolysis process, and random nucleation may be in charge of the main pyrolysis stage. This study can provide a theoretical basis for the thermochemical conversion and utilization of wheat straw.
... Polanyi potential θ degree of surface coverage Prior to activation, the char was characterized for its pH, electrical conductivity (Jenway-4510, Staffordshire, UK) and ash composition (heating in muffle furnace at 800°C) as described elsewhere [17,18]. Water retention capacity of the char was calculated by adding it in various loading rates (1-5%, w/w) to a suspension of soil (20 g) and water (20 mL) that was stirred for 24 h. ...
Although the benefits of applying biochar for the purposes of soil conditioning and crop productivity enhancement have been demonstrated, relatively few studies have elaborated on its causal mechanisms, especially on the biochar–fertilizer interaction. Thus, in the present study, the ex-situ adsorptive potential of base activated biochar (BAB) towards plant nutrient immobilization and removal from aqueous solutions wasinvestigated. Napier grass (Pennisetum purpureum) was utilized as the precursor to prepare slow vacuum pyrolysed char and its affinity towards adsorption of urea was examined at various process conditions. Low sorption temperatures, moderate agitation speeds and high initial concentration were seen to favour greater urea uptake by BAB. The sorption was exothermic, physical, spontaneous and had a pseudo-second order kinetic fit. Both surface and intra-particle diffusion governed the removal and immobilization of urea. Furthermore, process mass transfer was limited by film diffusion of urea to the external surface of the BAB. Equilibrium studies suggested that Dubinin–Radushkevich is the most appropriate model to describe the urea-BAB behaviour with maximum uptake, estimated to be 1115 mg·g−1. Through such ex-situ analysis, it could be possible to have prior knowledge, quantification and differentiation of the potential of chars manufactured from various feedstocks. This could then be used as an effective screening step in designing appropriate biochar–fertilizer systems for soil conditioning and help reduce the time and effort spent otherwise in long-term field studies.
... Non-wood-derived biochars also have a higher cation exchange capacity (CEC): for example, Gaskin et al. (2008) reported a CEC almost five times higher for biochars produced from poultry litter (38 cmol⋅kg − 1 ) than for biochars produced from pine chips (5 cmol⋅kg − 1 ), under the same pyrolysis conditions. The application of biochar with a high CEC may enhance soil fertility by reversibly adsorbing cations and reducing nutrient loss through leaching (Uras et al., 2012;Yang et al., 2015). ...
... Vacuum pyrolysis typically takes place between 450 and 600 °C and 0.05 and 0.20 MPa of pressure [82]. It can be used to create high-quality, more porous biochar [83]. Microwave pyrolysis uses dielectric heating to produce thermal energy, which is then delivered remotely to the reactor to prevent any direct physical contact between the energy source and the reaction J o u r n a l P r e -p r o o f mixture [84]. ...
Biomass and plastics are two of the most common municipal solid wastes globally that have continuously placed a burden on the environment. It is therefore important that they are properly recycled. Thermochemical co-conversion offers a valuable opportunity to recycle biomass and plastics simultaneously into biochar, which reduces the time and cost of recycling them individually while producing a material with a wide range of applications. This study is a review of published literature that discusses the thermochemical co-processing of biomass and plastic wastes into biochar. It was observed that co-pyrolysis and co-hydrothermal carbonization are the most commonly utilized technologies for this process. The characteristics of different biomass and plastics that have been thermochemically converted into biochar were compared. The properties of the resulting biochar are affected by the feedstock composition, pre-treatment and blending ratio, the reactor's configuration, reaction temperature, and the presence of a catalyst. Most studies found that treating the feedstocks separately resulted in a lower yield of biochar than processing them together. The biochar created by this procedure has been used as a soil additive and as an adsorbent for water treatment. Future perspectives and suggestions, such as the necessity for some technical advancement, biochar's economic benefits, improved government participation, and raised social awareness, were also made. These factors have the potential to propel this field of study to great horizons.
... This assures maximum aqueous production efficiency. Uras et al. suggest that not only the yield but also this process increases the porosity of BC which creates a variety of micro-as well as macro-porous forms [81]. ...
Various compounds that are emerging contaminants pose a significant risk to aquatic ecosystems and human health due to their potential to harm human health and the environment.Thus, there is an urgent requirement to use effective remediation methods and techniques to minimize the harmful impact of these contaminants on the environment. Biochar (BC) is a lightweight black residue that is made of carbon after the pyrolysis of biomass. BC is a product that is stable, rich in carbon, and exhibited improved properties. BC has come up with fascinating properties and results to remediate these pollutants from the soil effectively. Furthermore, it becomes possible to recover resources using BC because of the benefits such as (a) it offers in terms of cost, (b) the preservation of nutrients, and (c) the efficiency with which it absorbs pollutants. Consequently, it is necessary to have a knowledge of the interaction involving biochar and resource recovery to explore the applicability of BC in the cleaning up of the surroundings and the exploitation of wastewater. This review emphasize the physio-chemical and biological modification methods for the preparation of various types of engineered BC. Therefore, the present review aims: (i) provide an overview of emerging pollutants of human activities in soil (ii) synthesis and engineer BC for field application (iii) critically discuss and evaluate the factors affecting large-scale application techno-economic challenges. The review provided insight into the areas that need immediate attention in the upcoming investigation regarding the use of engineered biochar for wastewater treatment.
... This is shown by higher CCE and high pH [12] values for potato waste biochar relative to pine bark. Such high pH values have been previously seen in literature ranging from slightly acidic (4) to highly alkaline [13], depending on the feedstock and pyrolysis temperature [59,60] and are supported by the presence of carbonates in the FTIR (Table 6) and consequent high CCE. Similar findings were reported for tomato biochar [61]. ...
Large amount of wastes are burnt or left to decompose on site or at landfills where they cause air pollution and nutrient leaching to groundwater. Waste management strategies that return these food wastes to agricultural soils recover the carbon and nutrients that would otherwise have been lost, enrich soils and improve crop productivity. This study characterised biochar produced by pyrolysis of potato peels (PP), cull potato (CP) and pine bark (PB) at 350 and 650°C. The biochar types were analysed for pH, phosphorus (P) and other elemental composition. Proximate analysis was done following ASTM standard 1762-84, while surface functional groups and external morphology characteristics were determined using FTIR and SEM; respectively. Pine bark biochar had higher yield and fixed carbon (FC), and lower ash content and volatile matter than biochar types from potato wastes. The liming potential of CP 650°C is greater than that of PB biochars. Biochar types from potato waste had more functional groups even at high pyrolysis temperature relative to pine bark. Potato waste biochars showed an increase in pH, calcium carbonate equivalent (CCE), K and P content with increasing pyrolysis temperature. These findings imply that biochar from potato waste may be valuable for soil C storage, remediating acidity and increasing availability of nutrients especially K and P in acidic soils.
... The pyrolysis process selects highly stable organic compounds resistant to thermal degradation and at the same time alters the carbon structure, resulting in a graphene-like end product (Elkhalifa et al., 2022;Wang et al., 2022). These physicochemical changes result in biochar with high resistance to biochemical degradation, high surface area, and low DOC release capacity, resulting in a promising sorbent for soil and water remediation (Uras et al., 2012). The amount of DOC that can be released from biochar and interact with BIOS is an important factor for studying competitive sorption because the organic molecules can competition for sorption sites at the mineral surface (Essington, 2003). ...
Water contamination by arsenic (As) affects millions of people around the world, making techniques to immobilize or remove this contaminant a pressing societal need. Biochar and iron (oxyhydr)oxides [in particular, biogenic iron (oxyhydr)oxides (BIOS)] offer the possibility of stabilizing As in remediation systems. However, little is known about the potential antagonism in As sorption generated by the dissolved organic carbon (DOC) from biochar, or whether DOC affects how As(V) interacts with BIOS. For this reason, our objectives were to evaluate the i) As(V) sorption potential in BIOS when there is presence of DOC from pyrolyzed biochars at different temperatures; and ii) identify whether the presence of DOC alters the surface complexes formed by As(V) sorbed in the BIOS. We conducted As(V) sorption experiments with BIOS at circumneutral pH conditions and in the presence of DOC from sugarcane (Saccharum officinarum) straw biochar at pyrolyzed 350 (BC350) and 750 °C (BC750). The As(V) content was quantified by inductively coupled plasma mass spectrometry, and the BIOS structure and As(V) sorption mechanisms were investigated by X-ray absorption spectroscopy. In addition, the organic moieties comprising the DOC from biochars were investigated by attenuated total reflectance Fourier transform infrared spectroscopy. The addition of DOC did not change the biomineral structure or As(V) oxidation state. The presence of DOC, however, reduced by 25 % the sorption of As(V), with BC350 being responsible for the greatest reduction in As(V) sorption capacity. Structural modeling revealed As(V) predominantly formed binuclear bidentate surface complexes on BIOS. The presence of DOC did not change the binding mechanism of As(V) in BIOS, suggesting that the reduction of As(V) sorption to BIOS was due to site blocking. Our results bring insights into the fate of As(V) in surface waters and provide a basis for understanding the competitive sorption of As(V) in environments with biochar application.
... In Table 4 presents the characteristics of selected biochars derived from plant and waste biomass obtained at different pyrolysis temperatures [56,92,[115][116][117][118][119][120][121][122][123][124][125][126]. The presented data comes from the literature of the subject and is consistent with the results obtained by the authors of the publication. ...
Biochar from forest biomass and its remains has become an essential material for environmental engineering, and is used in the environment to restore or improve soil function and its fertility , where it changes the chemical, physical and biological processes. The article presents the research results on the opportunity to use the pyrolysis process to receive multifunctional biochar materials from oak biomass. It was found that biochars obtained from oak biomass at 450 and 500 °C for 10 min were rich in macronutrients. The greatest variety of the examined elements was characterized by oak-leaf pyrolysate, and high levels of Ca, Fe, K, Mg, P, S, Na were noticed. Pyrolysates from acorns were high in Fe, K, P and S. Oak bark biochars were rich in Ca, Fe, S and contained nitrogen. In addition, biomass pyrolysis has been found to improve energy parameters and does not increase the dust explosion hazard class. The oak biomass pyrolytic at 450 and 500 °C after 10 min increases its caloric content for all samples tested by at least 50%. The highest caloric value among the raw biomass tested was observed in oak bark: 19.93 MJ kg −1 and oak branches: 19.23 MJ kg −1. The mean and highest recorded Kst max were 94.75 and 94.85 bar s −1 , respectively. It can be concluded that pyrolysis has the potential to add value to regionally available oak biomass. The results described in this work provide a basis for subsequent, detailed research to obtain desired knowledge about the selection of the composition, purpose, and safety rules of production, storage, transport and use of biochar materials.
... A small peak was observed at 647 cm -1 , which is characteristic of a C-H bond with a metal (Uras et al., 2012).The FTIR spectra of topsoil were characterized by principal aliphatic bands at the following wavelengths: 1374 cm -1 (CH 3 aliphatic deformation) Saleh et al., ...
Biochar creates a resistant soil carbon pool that is carbon-negative, provides long-lasting improvements in soil fertility and serves as a net withdrawal of atmospheric carbon dioxide stored in highly stable soil carbon stocks. The enhanced nutrient retention, improved soil fertility and water holding capacity of biochar-amended soil not only reduces the total fertilizer requirements, but also the climate and environmental impact of croplands with generally increased production. I hypothesized that biochar increases plant growth by ameliorating negative soil physicochemical, and enhancing microbial, properties with special relation to nutrient availability and contributes actively to modify ecosystem gas exchange. Moreover, I hypothesized that the rate of biochar application influences the rate of biochar surface oxidation, nature and mineralization of functional groups, when it was added to soil for a long period of time in a controlled environment. The present study focused on determining the potential of a wood-based, high temperature (1100°C) biochar, to increase strawberry plant growth and ecosystem gas exchange in topsoil and its influence on soil quality. The results discussed in this thesis were obtained from a long-term investigation conducted under controlled conditions and is novel because of its duration (18 months), and because of the use of biochar derived from demolition wood. There is currently much interest in utilising biochar as a soil amendment for increased soil health and for carbon sequestration and European and International voluntary standards for biochar safety are under review in the UK post-Brexit. All work on biochar to date, has utilised biochar from virgin wood or agricultural residues. To the best of my knowledge, this is the first study to quantify effects of biochar derived from demolition wood on soil health. The importance of this is twofold; firstly, the stock of virgin wood for biochar production is limited, therefore it is important to be aware of any dangers of ‘diluting’ virgin wood with unapproved feedstock during production, and secondly, it is possible that biochar from such feedstocks might be acceptable for restoration programmes of already contaminated land. Biochar (0, 2.5, 5, 10 and 15% w/w) was mixed with topsoil, added to 14 L pots and maintained in a growth room at 20/16°C (16 hours day/night) and 50 % relative humidity for 18 months. Pots were either planted or left bare and soils in planted and unplanted pots were regularly sampled for microbiological and soil chemical determinations and plant growth measured. Biochar addition did not affect strawberry shoot growth or carbon or nitrogen content, but the 2.5% addition of biochar slightly increased root biomass, whilst the highest concentration (15%), reduced biomass relative to the 2.5% amendment, but not to the control. In the strawberry shoot, K, P, Zn, Cu, and As concentrations increased with biochar addition, while Pb content decreased with increasing rate of biochar compared to the control. Other than these, none of the shoot or root elements analysed exhibited clear biochar-driven trends. Neither leaf conductance nor leaf temperature were affected by biochar amendment. However, biochar amendment generally reduced ecosystem respiration (Re), net ecosystem exchange (NEE), gross ecosystem exchange (GEE) and soil enzyme activities. Biochar had no effect on microbial biomass nitrogen and carbon. CO2 and CH4 fluxes in soil were generally reduced by biochar amendment, but presence or absence of strawberry plants had no effect. However, soil water content, pH and Olsen P concentrations all increased with biochar amendment, as did soil nitrate concentrations in unplanted soils (but not as markedly in the presence of plants). Bulk density of the soil deceased in line with increasing biochar addition. Results from FTIR analysis showed that when this high temperature wood biochar was applied to soil, due to microbial and plant mediated transformation, it becomes more aromatic because of the loss of aliphatic and labile compounds and broadening of aromatic bands. The maximum number of functional groups (aliphatic, aromatic and carbohydrates) was recorded in the control soil (0 % biochar) both with and without plants. Aromatics (C-C and CH) were more prevalent than oxygen containing compounds (carboxyl and carbonyl), or aliphatic compounds and there were very few hydrocarbons. Shifts in the spectra for all wave numbers were observed in planted biochar-amended soils compared to control (0 % biochar). After 12 months, a marked decrease in spectral bands between 500 and 4000 cm−1 was noted in treatments with 2.5 %, 10 % and 15 % biochar. Overall, the use of biochar made from demolition wood ought to be avoided in agricultural settings. However, in contaminated areas, concentrations up to the lowest used in this study may be beneficial if pH changes or improvements in bulk density are desired.
... This implies that the secondary reactions are avoided, and the bio-oil yield is enhanced. Also, vacuum treatment is also beneficial to produce biochar with high porosity (Uras et al., 2012). This process can pyrolyze larger particles without any carrier gas (Bridgwater, 2012). ...
Value-added materials such as biochar and activated carbon that are produced using thermo-chemical conversion of organic waste have gained an emerging interest for the application in the fields of energy and environment because of their low cost and unique physico-chemical properties. Organic waste-derived materials have multifunctional abilities in the field of environment for capturing greenhouse gases and remediation of contaminated soil and water as well as in the field of energy storage and conversion. This review critically evaluates and discusses the current thermo-chemical approaches for upgrading organic waste to value-added carbon materials, performance enhancement of these materials via activation and/or surface modification, and recent research findings related to energy and environmental applications. Moreover, this review provides detailed guidelines for preparing high-performance organic waste-derived materials and insights for their potential applications. Key challenges associated with the sustainable management of organic waste for ecological and socioeconomic benefits and potential solutions are also discussed.
... A literature review showed that studies on pyrolysis of orchard wastes were mainly concerned on olive trees [28][29][30][31] and vineyard pruning residues [32][33][34][35]. Because of the insufficient amount of data on pruning residues from the main orchard trees cultivated in the territory of our country (Poland), we focused our study on the production and analysis of the biochars obtained from pruning residues of apple, pear, and plum. ...
The routine pruning and cutting of fruit trees provides a considerable amount of biowaste each year. This lignocellulosic biomass, mainly in the form of branches, trunks, rootstocks, and leaves, is a potential high-quality fuel, yet often is treated as waste. The results of a feasibility study on biochar production by pyrolysis of residues from orchard pruning were presented. Three types of biomass waste were selected as raw materials and were obtained from the most common fruit trees in Poland: apple (AP), pear (PR), and plum (PL) tree prunings. Two heating rates and three final pyrolysis temperatures were applied. For the slow (SP) and fast pyrolysis (FP) processes, the heating rates were 15 °C/min and 100 °C/min, respectively. The samples were heated from 25 °C up to 400, 500, and 600 °C. Chemical analyses of the raw materials were conducted, and the pyrolysis product yields were determined. A significant rise of higher heating value (HHV) was observed for the solid pyrolysis products, from approximately 23.45 MJ/kg for raw materials up to approximately 29.52 MJ/kg for pyrolysis products at 400 °C, and 30.53 MJ/kg for pyrolysis products at 600 °C. Higher carbon content was observed for materials obtained by fast pyrolysis conducted at higher temperatures.
... The higher value of pH and EC were due to the presence of salts and alkalinity. Furthermore, the K content of banana waste biochar was 8.56% followed by almond shells biochar, which means that those biochars can affect EC values (Uras et al. 2012). Furthermore, we have found that the four biochars had relatively high K and Na content (Table 3). ...
Around the world, the increasing population and consumption are placing huge demands on food. Agriculture is considered one of the important sectors in the world and the force to feed humanity. While under these circumstances, which stand out by successive years of drought, degradation of soil, climate change, and global warming, this sector has multifaceted a major issue that goes beyond threatening food security. Thus Morocco characterized by an arid and semi-arid climate is one example of countries that suffered from those problems. Due to lack of rain the water resources of some Moroccan arable lands are consumed highly as well as the quality of its soils is now degraded. This issue calls for new approaches to amending the degraded soils in these regions and sustain water supplies. Indeed, biochar can be a remedy for these poor soils; in fact, it has an incredible sequester carbon on soil, a benefit on the environment as well as on plant growth. Despite its virtues, certain biochars contain phytotoxic compounds. In this study, four biochars prepared from banana waste, peanut hull, almond shells, and walnut shells were tested on three plant species (cress to test (HAP), barley for assessing heavy metals, and lettuce to assess salinity) before any field application. The chemical and physical analysis was done for the four biochars and the sandy soil, the four biochars were also analyzed by scanning electron microscopy (SEM) for identifying the morphology of each biochar. The results showed that the four biochars enhanced water holding capacity (WHC), the four biochars revealed the existence of heavy metals especially for almond shells biochar and walnut shells biochar. While for the morphology of each biochar, banana waste biochar (BC-BW) and peanut hull biochar (BC-Peh) had pores more than almond shells biochar (BC-Alm) and walnut shells biochar(BC-WS). Concerning the phytotoxic tests, the lettuce was germinated in all biochars treatments except for the 8% biochar banana treatment, for the cress and barley, all the treatments were grown.
... RH-BC also enhanced the uptake of primary macro nutrients by maize plants, while the concentration of Mn, Cu, and Fe was high in plants grown in SF-BC because micronutrients were high in SF-BC composition. Nitrogen makes biochar a potential amendment, and after application in soil, the inorganic forms of N, i.e., NH 4 + and NO 3 − , are used for plant growth (Uras et al. 2012). The availability of K and P showed a beneficial effect on maize biomass production in this study, and similar results were reported based on biochar effects on maize growth in the past by Pandit et al. (2018). ...
Biochar application variably affects nutrients availability, growth, and yield of crop plants based on their feedstock type and pyrolysis conditions. A pot experiment was carried out to evaluate the effect of biochars prepared from three different feed stocks viz. sugarcane filter cake (SF-BC), farmyard manure (FM-BC), and rice husk (RH-BC), on the availability of the plant nutrients in soil and the growth and nutrient uptake by maize crop (Zea mays L.). The biochars were applied separately to the soil at the rate of 0, 0.25, 0.5, and 1% separately, and the experiment was laid out according to two-factor factorial completely randomized design (CRD) maintaining three replications. Maize variety Monsanto-DK8031 was sown as the test crop. The concentration of total nitrogen (N), nitrate (NO3-N), ammonium (NH4-N), microbial biomass nitrogen (MBN), Olsen phosphorus (P), and extractable K increased with the addition of FM-BC, while the SF-BC increased soil microbial biomass phosphorus (MBP) and micronutrients (Zn, Mn, Cu, Fe) availability in the soil. Moreover, the biochar application significantly improved crop growth parameters (i.e., plant height, fresh plant weight and dry biomass) and also increased plant nutrient concentration and uptake. No negative impact of biochar was observed on plant growth or nutrients concentration. The macronutrient (total N, P, and K) contents and their uptakes were higher in plants grown with RH-BC, while the micronutrient (Mn, Cu, and Fe) contents were higher in plants grown with SF-BC. Biochar as an organic amendment has a great potential to improve soil fertility status and nutrients availability to crop plants in tropical alkaline soils; however, the effectiveness varies with the feed stock type and application rate.
... To date, a number of studies have focused on the impact of biochar derived from plant materials in other countries such as China, Germany and Australia to improve soil quality (Agegnehu et al., 2017;Macdonald et al., 2014;Zhao et al., 2014). In South Africa, invasive tree species such as Eucalyptus, Acacia, Pinus, and black wattle (Lusiba et al., , 2018 and organic materials such as sugarcane bagasse and vineyard pruning (Sika and Hardie, 2014;Uras et al., 2012) were characterized and evaluated as potential biochar feedstock types for improving physical and chemical soil properties and crop growth in different soils. The studies indicated that biochar derived from various plant species has the potential to improve soil fertility; however, the type of feedstock and pyrolysis conditions have a greater influence on the benefit of biochar in soils. ...
... For instance, at a high temperature, volatile materials are removed quickly which results in high micro-pore volume in the biochar (Wang and Wang, 2019). Micro-porous structure and a large surface area make biochar appropriate for diverse use such as soil quality enhancement and carbon storage (Schaffer et al., 2019;O'Connor et al., 2018;Sun et al., 2017;Pröll et al., 2017;Uras et al., 2012), wastewater treatment (Mohan et al., 2014;Antunes et al., 2017Antunes et al., , 2018Qambrani et al., 2017;Oliveira et al., 2017;Shang et al., 2016;Xie et al., 2015;Tan et al., 2015;Qian et al., 2015), pesticide remediation (Varjani et al., 2019), fuel and catalyst in energy recovery technologies (Waqas et al., 2018;Amin et al., 2016), activated carbon production (Ioannidou and Zabaniotou, 2007;Alaya et al., 2000), removal of SO 2 and NO x from flue gases (Hu and Gholizadeh, 2019a). ...
Silver nanoparticles are one of the most beneficial forms of heavy metals in nanotechnology applications. Due to its exceptional antimicrobial properties, low electrical and thermal resistance, and surface plasmon resonance, silver nanoparticles are used in a wide variety of products, including consumer goods, healthcare, catalysts, electronics, and analytical equipment. As the production and applications of silver nanoparticles containing products increase daily, the environmental pollution due to silver nanoparticles release is increasing and affecting especially the aqueous ecosystem. Silver nanoparticles can kill useful bacteria in soil and water, and bioaccumulate in living organisms even at low concentrations from 10⁻² to 10 μg/mL silver can show antibacterial effect. On the other hand, the maximum silver discharge limit into freshwater is 0.1 μg/L and 3.2 μg/L for Australia and the USA, respectively. To reduce its toxic consequences and meet the regulatory guidelines, it is crucial to remove silver nanoparticles from wastewater before it is discharged into other water streams. Several technologies are available to remove silver nanoparticles, but the adsorption process using low-cost adsorbents is a promising alternative to mitigate silver nanoparticle pollution in the bulk stage. As one of the low-cost adsorbents, biochar produced from the biomass waste could be a suitable adsorbent. This review focuses on collating the latest evidence on silver nanoparticle production, applications, environmental consequences, and cost-effective technological approaches for silver removal from wastewater.
... To date, a number of studies have focused on the impact of biochar derived from plant materials in other countries such as China, Germany and Australia to improve soil quality (Agegnehu et al., 2017;Macdonald et al., 2014;Zhao et al., 2014). In South Africa, invasive tree species such as Eucalyptus, Acacia, Pinus, and black wattle (Lusiba et al., , 2018 and organic materials such as sugarcane bagasse and vineyard pruning (Sika and Hardie, 2014;Uras et al., 2012) were characterized and evaluated as potential biochar feedstock types for improving physical and chemical soil properties and crop growth in different soils. The studies indicated that biochar derived from various plant species has the potential to improve soil fertility; however, the type of feedstock and pyrolysis conditions have a greater influence on the benefit of biochar in soils. ...
The balance in nutrient availability and retention after addition of biochar depends on the feedstock and application rates of the biochar in different soils. A pot experiment was conducted to assess the potential effect of biochar derived from poultry litter (PLB) and acacia (ACB) feedstocks on selected rhizospheric macro and micro-nutrients, shoot and root biomass, as well as nutrient uptake by chickpea grown in three different soil types. Treatments consisted of two biochar (PLB and ACB), four application rates of 0 (control), 0.5, 1 and 2% w/w, and three soil types [Fernwood (Arenosol); Pinedene (Gleyic Acrisol); Griffin (Helvic Acrisol)]. PLB application at 2% increased rhizospheric pH, CEC, and P, K, Ca, Mg, S, Zn concentrations in Pinedene and Griffin soils. Chickpea shoot and root biomass in the Pinedene and Griffin soils were highest at 0.5 and 1% PLB application and was attributed to increase in soil N and N uptake. Application of PLB and ACB at 1 and 2% showed a significant change in rhizospheric pH and available P in Fernwood soil resulting in a reduction of Fe concentration. The higher C:N ratio of the ACB probably resulted in immobilization of nutrients as evident from the low response in shoot and root biomass as well as shoot N uptake of chickpea in all soil types. The study confirmed that the effect of biochar on the availability of soil nutrients and plant growth is associated with the nature of the biochar feedstock, the rate of application and the soil characteristics.
... Furthermore, applying biochar increased soil water retention as described by Laghari et al. (2015); Uras et al. (2012) who reported that biocharred materials had a more significant effect on the moisture content of sandy soil at field capacity which increased by 18%, 21.5%, and 50%, ...
Raising a sandy soil's ability to retain more water is an important strategy to manage sandy soils. Combined application of biochar and slurry was hypothesized to be an appropriate strategy for improving soil hydro‐physical properties. A two‐season field trial was conducted by cultivating peanut (Arachis hypogaea L.) on a sandy soil under permanent overhead sprinkler irrigation. Rice straw biochar at 0, 10, 20, and 30 Mg ha‐1 and biogas slurry at 0, 5, 10, and 15 Mg ha‐1 were applied. Results indicated that all biogas slurry rates were more effective than biochar on improving all investigated parameters apart from infiltration rate and hydraulic conductivity which were higher with 30 Mg ha‐1 of biochar than with 15 Mg ha‐1 of slurry. Soil bulk density (g m‐3) decreased significantly from 1.76 for the control to record 1.72 and 1.62 under biochar and slurry, respectively. Soil moisture contents at different tensions were the highest under the maximum combination rates, while biochar singly gave lower contents than slurry. The combined effect of 10 and 15 Mg ha‐1 biochar and slurry, respectively surpassed their individual effects. With strong coefficients of determination (R2 ranges from 0.88 to 0.98) and identical curves of estimated and predicted variables, it is possible to have accurate predictions for the changes in soil hydro‐physical properties linked with different combinations of biochar and biogas slurry.
Biomass as a renewable source of energy can also be efficiently utilized to produce biochar and pyroligneous acid (PA) through the pyrolysis process which is influenced by parameters like feedstock moisture content (FMC), pyrolysis residence time (PRT) and chimney inclination angles (CIA) for a given kiln. Even though the process is efficient, there exists scarce knowledge on optimization of these parameters to achieve the best condition that will result in a high production and quality of biochar and PA. The main objective of this research was to evaluate the effect of the above pyrolysis parameters on the production and quality of the biochar and PA. An experimental insulated metallic carbonization kiln (1 m high and 0.5 m diameter) with a water condensing system (1 m high and 0.32 m diameter through which a 0.18 m diameter and 1 m length chimney passed) was developed and used. Twigs (100 kg) from acacia, eucalyptus and black wattle were used at FMC of 20%, 15% and 10% for the pure stocks and a 1:1:1 mixture was carbonized. The chimney inclination angles of 30o, 45o and 60o were tested. Pyrolysis was carried out at a temperature of approximately 400oC and a selected residence time (in minutes) of 90, 135 and 180. For each feedstock, FMC, PRT and CIA, the production and the quality of biochar and PA were determined. Biochar quality was based on pH, moisture content (MC), volatile matter (VM), ash content (AC) and fixed carbon (FC) while PA was classified using pH and density. The Response Surface Methodology using Box-Behnken Design technique was used to develop and optimize an equation relating production and quality of biochar and PA to varied parameters. The combined optimal condition for the products were attained at FMC = 10%, PRT = 164.55 minutes and CIA = 30o resulting to biochar production of 43.17%, MC = 3.24%, VM = 23.95%, Ash = 3.33%, FC = 67.39% and pH = 9.50 and PA production of 23.57%, ρ = 1.24 gcm-3 and pH = 2.97. From the analyzed data (α = 0.05), the biochar production was influenced by all the varied parameters while both FMC and PRT had a significant effect on its quality. FMC, PRT and CIA had a significant influence on the PA production while its quality was only influenced by PRT. The mathematical equation developed had a composite desirability of 0.7756 at p-value ≤0.05 which made it viable hence, serving as a guiding principle to any user of the developed pyrolysis system. These research findings are of importance since pyrolysis of the biomass would result in environmental conservation and also serve as a source of livelihood when these products are marketed.
The review provides a thorough assessment of current developments in biomass pyrolysis research, including both basic research and technological applications. Recent advances in pyrolysis-characterization methods, particularly on the online characterization of biomass pyrolytic intermediates and spectroscopic and microscopic imaging methods for biochar and bio-oil are discussed. Then, relevant optimization and regulation approaches for the biomass pyrolysis process are discussed in light of the demands made to enhance the physicochemical features of the relevant pyrolysis products. Previous studies have shown that co-pyrolyzing biomass with another feedstock can improve the physicochemical characteristics of the pyrolysis products and efficiently realize waste recycling. As a result, this study includes a thorough assessment of current developments in biomass co-pyrolysis using four different feedstocks (coal, plastics, tyres, and sludge). Recent activities of catalytic biomass pyrolysis, or catalytic co-pyrolysis, are also described as an essential part of general biomass pyrolysis. Reactor design aspects and economic evaluation of pyrolysis technologies have been reviewed. Additionally, two cutting-edge heating techniques (microwave heating and solar heating) for biomass pyrolysis are discussed, and their advantages and disadvantages are contrasted with those of the traditional heating approach. This review is concluded with some predictions for the development of biomass pyrolysis in the future.
Amongst the advanced biomass conversion technologies, thermochemical processes have potential applicability, becoming the key technologies to support a new waste management strategy by optimizing it. This review relies on thermochemical conversion processes including pyrolysis, gasification, and hydrothermal liquefaction for turning agricultural wastes into biofuels (bio-oil, biochar, and syngas), explicitly addressing their technological principles, implementation prospects, and operating parameters. The feasibility of thermochemical conversion technologies is considered from economic and environmental viewpoints along with life cycle assessment analysis. This paper sheds light on multiple agricultural wastes analyzed for biofuel production through thermochemical conversion. The differences between the characteristics of the identical agricultural waste samples and different agricultural waste samples are exhibited here, which vary due to their geographical location of cultivation and the various growing conditions. Furthermore, a thorough review of the literature regarding the characterization techniques for feedstock, the characterization methods for the generated biofuels, and their proper utilization in various applications are also covered.
Research on using biochar for environmental applications has witnessed unprecedented advances in the past decade. Biochar is universally considered one of the best alternatives to store carbon to fight global warming. Thus, the sequential use of biochar in environmental remediation compatible with carbon sequestration is receiving growing attention. One of the reasons for such huge interest is the possibility to engineer biochar with targeted properties (e.g., surface area and chemistry) relevant to existing environmental issues. These properties can be achieved by selecting appropriate raw materials, processing conditions, carbonization technology, and the possibility of selecting postproduction modification approaches. The objective of this review is to summarize strategies to enhance biochar properties relevant to its use in environmental services (e.g., water purification, air/gas cleaning, construction materials, soil amendments) and the corresponding results on the use of this material for these applications. The main methods for enhancing biochar properties for environmental applications reviewed include activation (physical and chemical), oxidation, metal and metal oxide modification, metal-free heteroatom doping, and biological modification. Both modified and unmodified biochars have been used for soil amendments as adsorbents of pollutants in the aqueous phase (e.g., removal of P and N, heavy metals, and organic pollutants), adsorbents of pollutants in the gas phase (e.g., biogas cleaning), as a catalyst, as an additive for improving anaerobic digestion, and as an admixture to cementitious/construction materials, with promising results in all cases. New opportunities for using biochar are being reported as the science of biochar production, modification, and use advances.
Cd long-term immobilization by biochar and potential risk in soils with different pH were quantified under a combined artificial aging, which simulated five years of aging in the field based on local climate. Two biochars (original and KMnO4-modified) and five soils with different pH were tested, and an improved three-layer mesh method was employed in this study. Five aging cycles were carried out (Cycle 1–Cycle 5), and each aging cycle quantitatively simulated 1 year of natural aging. As the aging time increased, Cd leaching loss in all soils gradually increased from Cycle 1 to Cycle 5; for relatively stable Cd fraction, it decreased firstly and then stabilized in acidic and neutral soils (S1–S4), while it decreased firstly and then increased in alkaline soil (S5). Biochars significantly promoted Cd immobilization in strongly acidic soil (S1) by increasing relatively stable fractions and decreasing leaching loss. For weakly acidic and neutral soils (S2–S4), although biochars still had positive effects, the immobilization effects were weakened to certain extents compared with S1. The percentage of Cd leaching loss decreased by 19.12% in strongly acidic soil (S1) and by 1.12–11.35% in weakly acidic and neutral soils (S2–S4) after modified biochar treatment. For alkaline soil (S5), the application of biochars had negative effects on Cd immobilization by decreasing relatively stable fractions and increasing leaching loss, and posed risks to the environment. For strongly acidic soil (S1) and weakly acidic and neutral soils (S2–S4), the percentages of relatively stable fractions increased from 6.09–19.93% to 24.98–36.70% after modified biochar treatment. However, for alkaline soil, the percentage of relatively stable fractions decreased from 55.27% to 53.93% after biochar treatment. The more acidic the soil, the more effective the Cd immobilization by biochar. Biochars with high pH level are not suitable for the remediation of alkaline Cd contaminated soil.
Biochar is an organic and pyrogenic material produced by pyrolysis of animal or plant-based feedstocks. In recent days, biochar has gained much attention due to its unique physiochemical properties and distinct role in improving the soil biological and physiochemical properties, carbon sequestration and remediation of organic and inorganic pollutants. However, performance of biochar in a specific role is largely dependent on its physiochemical properties which are influenced by biochar preparation conditions. The specific aim of this review paper is to highlight the impact of different biochar preparation conditions including pyrolysis temperature, type of feedstock and acid modifications on physiochemical properties of biochar such as pH value, pore volume, cation exchange capacity (CEC), volatile matter, specific surface area (SSA), carbon and ash contents. Biochar produced at higher pyrolysis temperature contains high pH, carbon and ash contents, high porosity and specific surface area but with lower volatile matter and cation exchange capacity values. The aforementioned changes occurred due to substantial decomposition of organic materials at high pyrolysis temperature. Biochar obtained from solid waste and animal manure feedstocks contains lower volatile matter, carbon contents and specific surface area but higher cation exchange capacity than biochar derived from wood and crop residue feedstocks. These changes are mainly attributed to profound variations in moisture, cellulose and lignin contents of feedstocks. Acid modification of biochar with oxalic acid, citric acid, sulphuric acid, phosphoric acid and hydrochloric acid increases surface functional groups (hydroxyl, carbonyl and carboxyl), specific surface area and porosity while pH value is decreased. The findings of this review paper suggest that a cost-effective and specific type of biochar with desirable physiochemical attributes can be prepared based on biochar preparation conditions, to solve specific environment or agriculture-related problems.
Existe la necesidad de sustituir componentes de los sustratos para el desarrollo de las plántulas en vivero forestal, por productos de bajo costo y sobre todo por materiales renovables. El biocarbón es liviano, poroso y presenta una alta capacidad de retención de agua. Por lo anterior, el objetivo de este estudio fue evaluar el uso de biocarbón a base de bagazo de caña de azúcar en la producción de plantas de pino prieto (Pinus greggii Engelm. ex Parl.), bajo condiciones de vivero. Se evaluaron cuatro tratamientos: (a) biocarbón con suelo forestal, (b) sustrato forestal (mezcla de 12.5% peat moss, 12.5% agrolita, 25% vermiculita y 50% corteza de pino), (c) biocarbón con sustrato forestal, ambos en una relación 1:9 (biocarbón:suelo, biocarbón:sustrato), y (d) suelo forestal solo. Se evaluó el efecto del biocarbón y de la fertilización (N, P y K) en el desempeño de los tratamientos en suelo y sustrato forestal. Las variables evaluadas fueron: altura de planta, diámetro de tallo, biomasa aérea, biomasa radical, biomasa total aérea, a relación biomasa aérea/radical; además la concentración de nutrientes acumulados (N, P, Ca, Mg, K y Na) en la parte aérea y radical. Los resultados obtenidos indican que como resultado de la adición de biocarbón al suelo y la fertilización, la altura, diámetro, biomasa (aérea y total) de pino prieto, fueron semejantes a las obtenidas en sustrato forestal, solo o combinado con biocarbón. Estos resultados se asociaron a la adición de biocarbón al suelo que incrementó la absorción de N y su concentración en la biomasa aérea, y favoreció la disponibilidad de Mg, Ca, K y P, éstos dos últimos elementos adicionados en la fertilización. Se concluye que la combinación de biocarbón y suelo en una relación (1:9) (p/p) con adición de fertilizante (N, P y K) puede ser empleado en el desarrollo de Pinus greggii Engelm ex Parl en vivero.
This chapter provides an elaboration on the agricultural productivity, resources, and waste management of Asian countries particularly on its high-value crops such as rice, corn, pineapple, coconut, sugarcane, and oil palm. It presents a comprehensive detail on the biomass waste generation from the various crops, its characteristics, and the different thermal conversion processes of agricultural wastes into biochar. The authors aim to provide an effective way to efficiently utilize the agricultural wastes into value-added products as current state of the art in bioenergy generation and utilization for sustainable and green technology innovation.
Increased industrial growth in the world serves a significant role in the water contamination with heavy metals. Heavy metals such as arsenic, copper, lead, chromium, mercury, nickel, and cadmium impart several health hazards to humans, plants, and animals. Moreover their accumulation potential disturbs the food chain. Freshwater demand is higher in the world which may lead to a severe water crisis in the upcoming years. Hence feasible water treatment technologies must be identified and its efficiency must be concentrated. Heavy metals bear the risk of biodegradation and transformation. Hence adsorption is found to be an attractive method nowadays for sequestration of such metals. It is an economically feasible and eco-friendly method. Biochar is advantageous over other adsorbents such as activated carbon, graphene, silica, etc. It is the product of a thermochemical process which possesses better adsorption capacity. It reduces the production time and in addition provides fuel. Different pyrolysis conditions influence the quantity and yield of char. The degree of biochar adsorption is mainly focused on the type of biomass used, metal species concentrated, functional groups, and surface area of the biochar. Regeneration of biomass is also an important phenomenon to be considered as the adsorbed biochar may cause secondary pollution if not disposed in a proper manner. In order to improve the surface properties, physical structure, and regeneration capacity of biochar, various modification technologies have been adopted. It will also pave way for the effective utilization of waste biomaterials in wastewater treatment. The modification may be carried out before pyrolysis or after pyrolysis. It is categorized under physical, chemical, magnetic, and mineral impregnation methods. This review focuses on the mechanism and improvements of the treated biochar in comparison to the pristine biochar for heavy metal sequestration.
Bioethanol produced from waste lignocellulosic biomass is a promising renewable fuel in environmental and sustainable views. The thermochemical process that can readily decompose lignocellulosic biomass to carbohydrate‐rich bio‐oil is more appealing compared to biochemical process due to its low costs and less time. However, levoglucosan, the dominant carbohydrate present in the bio‐oil, is problematic to be efficiently converted to bioethanol by native and recombinant microorganisms. Here, a synthetic metabolic pathway based on the heterologous genes encoding levoglucosan kinase, pyruvate decarboxylase, and alcohol dehydrogenase, was constructed and introduced into Escherichia coli to generate new platforms for ethanol production from levoglucosan. The engineered E. coli strains overexpressing levoglucosan kinase could, for the first time, completely consume 1–2% (wt/vol) levoglucosan present in the minimal media to produce ethanol with relatively high yield; while E. coli LGE2 exhibited the maximal ethanol yield of 0.43 g/g levoglucosan, rising by ~23% compared to the only existing recombinant strain E. coli KO11 + lgk. Although levoglucosan utilization was inferior to the utilization of other substrates like fructose and complex media, our results suggest that desired high‐yield bioethanol production from levoglucosan‐based minimal media could be efficiently achieved by the newly engineered strains, which could provide a solution for complete bioethanol fermentation from the thermochemically decomposed biomass feedstock.
Biomass pyrolysis has been the focus of study by several researchers as a viable means of producing biofuels and other useful products. This paper gives a comprehensive, elaborate and updated review of pyrolysis technology as an efficient thermochemical route for biomass conversion. Pyrolysis products include pyrolytic gas, bio-oil, and solid biochar. Depending on the operating conditions, pyrolysis is usually classified as slow, intermediate, fast, and flash pyrolysis. The utilization of special catalysts can help facilitate pyrolytic gas production, while specific pretreatment processes can help facilitate bio-oil production. The efficiency of the pyrolysis process is affected by a number of factors such as temperature, heating rate, residence time, particle size, biomass type, and biomass pretreatment method. In this review, thermogravimetric analysis and kinetic modelling of biomass pyrolysis were also emphasized while the various constraints encountered during biomass pyrolysis have been highlighted and suggestions made to address them. More recently, more advanced experimental methods have been developed for biomass pyrolysis research, and these include Py-GC–MS/FID, TG-MS/TG-FTIR, in situ spectroscopy for reaction progress analysis, isotopic labelling, and intermediate product analysis techniques that enable the monitoring of the biomass devolatilization process as well as identification of the functional groups of the volatiles and monitoring of the changes in the functional groups on the surface of biomass in the course of pyrolysis. No doubt, biomass pyrolysis will continue to provide several benefits and serve as a sustainable means of producing biofuels, biochemicals, and other valuable products with far-reaching areas of applications.
Fluorescence spectroscopy has, over the last two decades, been frequently used for studies of biological cells and their molecular components. In combination with molecular biological methods that allow introduction of fluorescent labeling in vivo and in vitro, fluorescence spectroscopy methods, such as Förster resonance energy transfer (FRET), have made membrane proteins accessible to studies of their molecular structure and dynamics. In this article, we describe a variety of fluorescence spectroscopy techniques and focus on their use in the studies of the physiological role ion channels play, and the conformational rearrangements involved in the gating of ion channels, whose function as gated membrane pores underlies numerous cellular processes essential for the survival of living cells and organisms.
Despite the recent interest in biochars as soil amendments for improving soil quality and increasing soil carbon sequestration, there is inadequate knowledge on the soil amendment properties of these materials produced from different feed stocks and under different pyrolysis conditions. This is particularly true for biochars produced from animal origins. Two biochars produced from poultry litter under different conditions were tested in a pot trial by assessing the yield of radish (Raphanus sativus var. Long Scarlet) as well as the soil quality of a hardsetting Chromosol (Alfisol). Four rates of biochar (0, 10, 25, and 50 t/ha), with and without nitrogen application (100 kg N/ha) were investigated. Both biochars, without N fertiliser, produced similar increases in dry matter yield of radish, which were detectable at the lowest application rate, 10 t/ha. The yield increase (%), compared with the unamended control rose from 42% at 10 t/ha to 96% at 50 t/ha of biochar application. The yield increases can be attributed largely to the ability of these biochars to increase N availability. Significant additional yield increases, in excess of that due to N fertiliser alone, were observed when N fertiliser was applied together with the biochars, highlighting the other beneficial effects of these biochars. In this regard, the non activated poultry litter biochar produced at lower temperature (450°C) was more effective than the activated biochar produced at higher temperature (550°C), probably due to higher available P content. Biochar addition to the hardsetting soil resulted in significant but different changes in soil chemical and physical properties, including increases in C, N, pH, and available P, but reduction in soil strength. These different effects of the 2 different biochars can be related to their different characteristics. Significantly different changes in soil biology in terms of microbial biomass and earthworm preference properties were also observed between the 2 biochars, but the underlying mechanisms require further research. Our research highlights the importance of feedstock and process conditions during pyrolysis on the properties and, hence, soil amendment values of biochars.
The vibrational spectrum of a molecule is considered to be a unique physical property and is characteristic of the molecule. As such, the infrared spectrum can be used as a fingerprint for identification by the comparison of the spectrum from an “unknown” with previously recorded reference spectra. This is the basis of computer-based spectral searching. In the absence of a suitable reference database, it is possible to effect a basic interpretation of the spectrum from first principles, leading to characterization, and possibly even identification of an unknown sample. This first principles approach is based on the fact that structural features of the molecule, whether they are the backbone of the molecule or the functional groups attached to the molecule, produce characteristic and reproducible absorptions in the spectrum. This information can indicate whether there is backbone to the structure and, if so, whether the backbone consists of linear or branched chains. Next it is possible to determine if there is unsaturation and/or aromatic rings in the structure. Finally, it is possible to deduce whether specific functional groups are present. If detected, one is also able to determine local orientation of the group and its local environment and/or location in the structure. The origins of the sample, its prehistory, and the manner in which the sample is handled all have impact on the final result. Basic rules of interpretation exist and, if followed, a simple, first-pass interpretation leading to material characterization is possible. This article addresses these issues in a simple, logical fashion. Practical examples are included to help guide the reader through the basic concepts of infrared spectral interpretation.
Natural organic biomass burning creates black carbon which forms a considerable proportion of the soil’s organic carbon. Due
to black carbon’s aromatic structure it is recalcitrant and has the potential for long-term carbon sequestration in soil.
Soils within the Amazon-basin contain numerous sites where the ‘dark earth of the Indians’ (Terra preta de Indio, or Amazonian Dark Earths (ADE)) exist and are composed of variable quantities of highly stable organic black carbon waste
(‘biochar’). The apparent high agronomic fertility of these sites, relative to tropical soils in general, has attracted interest.
Biochars can be produced by ‘baking’ organic matter under low oxygen (‘pyrolysis’). The quantities of key mineral elements
within these biochars can be directly related to the levels of these components in the feedstock prior to burning. Their incorporation
in soils influences soil structure, texture, porosity, particle size distribution and density. The molecular structure of
biochars shows a high degree of chemical and microbial stability. A key physical feature of most biochars is their highly
porous structure and large surface area. This structure can provide refugia for beneficial soil micro-organisms such as mycorrhizae
and bacteria, and influences the binding of important nutritive cations and anions. This binding can enhance the availability
of macro-nutrients such as N and P. Other biochar soil changes include alkalisation of soil pH and increases in electrical
conductivity (EC) and cation exchange capacity (CEC). Ammonium leaching has been shown to be reduced, along with N2O soil emissions. There may also be reductions in soil mechanical impedance. Terra preta soils contain a higher number of ‘operational taxonomic units’ and have highly distinctive microbial communities relative
to neighbouring soils. The potential importance of biochar soil incorporation on mycorrhizal fungi has also been noted with
biochar providing a physical niche devoid of fungal grazers. Improvements in soil field capacity have been recorded upon biochar
additions. Evidence shows that bioavailability and plant uptake of key nutrients increases in response to biochar application,
particularly when in the presence of added nutrients. Depending on the quantity of biochar added to soil significant improvements
in plant productivity have been achieved, but these reports derive predominantly from studies in the tropics. As yet there
is limited critical analysis of possible agricultural impacts of biochar application in temperate regions, nor on the likelihood
of utilising such soils as long-term sites for carbon sequestration. This review aims to determine the extent to which inferences
of experience mostly from tropical regions could be extrapolated to temperate soils and to suggest areas requiring study.
KeywordsBiochar-Black carbon-Biochar-Carbon sequestration-Charcoal-Climate change
Background
Biochar’s role as a carbon sequestration agent, while simultaneously providing soil fertility improvements when used as an amendment, has been receiving significant attention across all sectors of society, ranging from academia, industry, government, as well as the general public. This has lead to some exaggeration and possible confusion regarding biochar’s actual effectiveness as a soil amendment. One sparsely explored area where biochar appears to have real potential for significant impact is the soil nitrogen cycle.
Scope
Taghizadeh-Toosi et al. (this issue) examined ammonia sorption on biochar as a means of providing a nitrogen-enriched soil amendment. The longevity of the trapped ammonia was particularly remarkable; it was sequestered in a stable form for at least 12 days under laboratory air flow. Furthermore, the authors observed increased 15N uptake by plants grown in soil amended with the 15N-enriched biochar, indicating that the 15N was not irreversibly bound, but, was plant-available.
Conclusions
Their observations add credence to utilizing biochar as a carrier for nitrogen fertilization, while potentially reducing the undesired environmental consequences through gas emissions, overland flow, and leaching.
The objectives of this study were to assess the relative importance of either biotic or abiotic oxidation of biomass-derived black carbon (BC) and to characterize the surface properties and charge characteristics of oxidized BC. We incubated BC and BC–soil mixtures at two temperatures (30 °C and 70 °C), with and without microbial inoculation, nutrient addition, or manure amendment for four months. Abiotic processes were more important for oxidation of BC than biotic processes during this short-term incubation, as inoculation with microorganisms at 30 °C did not change any of the measured indicators of surface oxidation. Black C incubated at both 30 °C and 70 °C without microbial activity showed a decrease in pH (in water) from 5.4 to 5.2 and 3.4, as well as an increase in cation exchange capacity (CEC at pH 7) by 53% and 538% and in oxygen (O) content by 4% and 38%, respectively. Boehm titration and Fourier-transform infrared (FT-IR) spectroscopy suggested that formation of carboxylic functional groups was the reason for the enhanced CEC during oxidation. Analysis of surface properties of BC using X-ray photoelectron spectroscopy (XPS) indicated that the oxidation of BC particles was initiated on the surface. Incubation at 30 °C only enhanced oxidation on particle surfaces, while oxidation during incubation at 70 °C penetrated into the interior of particles. Such short-term oxidation of BC has significance for the stability of BC in soils as well as for its effects on soil fertility and biogeochemistry.
Biochar properties can be significantly influenced by feedstock source and pyrolysis conditions; this warrants detailed characterisation of biochars for their application to improve soil fertility and sequester carbon. We characterised 11 biochars, made from 5 feedstocks [Eucalyptus saligna wood (at 400 degrees C and 550 degrees C both with and without steam activation); E. saligna leaves (at 400 degrees C and 550 degrees C with activation); papermill sludge (at 550 degrees C with activation); poultry litter and cow manure (each at 400 degrees C without activation and at 550 degrees C with activation)] using standard or modified soil chemical procedures. Biochar pH values varied from near neutral to highly alkaline. In general, wood biochars had higher total C, lower ash content, lower total N, P, K, S, Ca, Mg, Al, Na, and Cu contents, and lower potential cation exchange capacity (CEC) and exchangeable cations than the manure-based biochars, and the leaf biochars were generally in-between. Papermill sludge biochar had the highest total and exchangeable Ca, CaCO(3) equivalence, total Cu, and potential CEC, and the lowest total and exchangeable K. Water-soluble salts were higher in the manure-based biochars, followed by leaf, papermill sludge, and wood biochars. Total As, Cd, Pb, and polycyclic aromatic hydrocarbons in the biochars were either very low or below detection limits. In general, increase in pyrolysis temperature increased the ash content, pH, and surface basicity and decreased surface acidity. The activation treatment had a little effect on most of the biochar properties. X-ray diffraction analysis showed the presence of whewellite in E. saligna biochars produced at 400 degrees C, and the whewellite was converted to calcite in biochars formed at 550 degrees C. Papermill sludge biochar contained the largest amount of calcite. Water-soluble salts and calcite interfered with surface charge measurements and should be removed before the surface charge measurements of biochar. The biochars used in the study ranged from C-rich to nutrient-rich to lime-rich soil amendment, and these properties could be optimised through feedstock formulation and pyrolysis temperature for tailored soil application.
The amendment of two agricultural soils with two biochars derived from the slow pyrolysis of papermill waste was assessed in a glasshouse study. Characterisation of both biochars revealed high surface area (115 m2 g−1) and zones of calcium mineral agglomeration. The biochars differed slightly in their liming values (33% and 29%), and carbon content (50% and 52%). Molar H/C ratios of 0.3 in the biochars suggested aromatic stability. At application rates of 10 t ha−1 in a ferrosol both biochars significantly increased pH, CEC, exchangeable Ca and total C, while in a calcarosol both biochars increased C while biochar 2 also increased exchangeable K. Biochars reduced Al availability (ca. 2 cmol (+) kg−1 to <0.1 cmol (+) kg−1) in the ferrosol. The analysis of biomass production revealed a range of responses, due to both biochar characteristics and soil type. Both biochars significantly increased N uptake in wheat grown in fertiliser amended ferrosol. Concomitant increase in biomass production (250% times that of control) therefore suggested improved fertiliser use efficiency. Likewise, biochar amendment significantly increased biomass in soybean and radish in the ferrosol with fertiliser. The calcarosol amended with fertiliser and biochar however gave varied crop responses: Increased soybean biomass, but reduced wheat and radish biomass. No significant effects of biochar were shown in the absence of fertiliser for wheat and soybean, while radish biomass increased significantly. Earthworms showed preference for biochar-amended ferrosol over control soils with no significant difference recorded for the calcarosol. The results from this work demonstrate that the agronomic benefits of papermill biochars have to be verified for different soil types and crops
This study examines the potential, magnitude, and causes of enhanced biological N2 fixation (BNF) by common beans (Phaseolus vulgaris L.) through bio-char additions (charcoal, biomass-derived black carbon). Bio-char was added at 0, 30, 60, and 90 g kg-1 soil, and BNF was determined using the isotope dilution method after adding 15N-enriched ammonium sulfate to a Typic Haplustox cropped to a potentially nodulating bean variety (CIAT BAT 477) in comparison to its non-nodulating isoline (BAT 477NN), both inoculated with effective Rhizobium strains. The proportion of fixed N increased from 50% without bio-char additions to 72% with 90 g kg-1 bio-char added. While total N derived from the atmosphere (NdfA) significantly increased by 49 and 78% with 30 and 60 g kg-1 bio-char added to soil, respectively, NdfA decreased to 30% above the control with 90 g kg-1 due to low total biomass production and N uptake. The primary reason for the higher BNF with bio-char additions was the greater B and Mo availability, whereas greater K, Ca, and P availability, as well as higher pH and lower N availability and Al saturation, may have contributed to a lesser extent. Enhanced mycorrhizal infections of roots were not found to contribute to better nutrient uptake and BNF. Bean yield increased by 46% and biomass production by 39% over the control at 90 and 60 g kg-1 bio-char, respectively. However, biomass production and total N uptake decreased when bio-char applications were increased to 90 g kg-1. Soil N uptake by N-fixing beans decreased by 14, 17, and 50% when 30, 60, and 90 g kg-1 bio-char were added to soil, whereas the C/N ratios increased from 16 to 23.7, 28, and 35, respectively. Results demonstrate the potential of bio-char applications to improve N input into agroecosystems while pointing out the needs for long-term field studies to better understand the effects of bio-char on BNF.
In the highlands of Western Kenya, we investigated the reversibility of soil productivity decline with increasing length of continuous maize cultivation over 100 years (corresponding to decreasing soil organic carbon (SOC) and nutrient contents) using organic matter additions of differing quality and stability as a function of soil texture and inorganic nitrogen (N) additions. The ability of additions of labile organic matter (green and animal manure) to improve productivity primarily by enhanced nutrient availability was contrasted with the ability of stable organic matter (biochar and sawdust) to improve productivity by enhancing SOC. Maize productivity declined by 66% during the first 35 years of continuous cropping after forest clearing. Productivity remained at a low level of 3.0 t grain ha-1 across the chronosequence stretching up to 105 years of continuous cultivation despite full N–phosphorus (P)–potassium (K) fertilization (120–100–100 kg ha−1). Application of organic resources reversed the productivity decline by increasing yields by 57–167%, whereby responses to nutrient-rich green manure were 110% greater than those from nutrient-poor sawdust. Productivity at the most degraded sites (80–105 years since forest clearing) increased in response to green manure to a greater extent than the yields at the least degraded sites (5 years since forest clearing), both with full N–P–K fertilization. Biochar additions at the most degraded sites doubled maize yield (equaling responses to green manure additions in some instances) that were not fully explained by nutrient availability, suggesting improvement of factors other than plant nutrition. There was no detectable influence of texture (soils with either 11–14 or 45–49% clay) when low quality organic matter was applied (sawdust, biochar), whereas productivity was 8, 15, and 39% greater (P
The forms of alkalis of the biochars produced from the straws of canola, corn, soybean and peanut at different temperatures (300, 500 and 700°C) were studied by means of oxygen-limited pyrolysis. The alkalinity and pH of the biochars increased with increased pyrolysis temperature. The X-ray diffraction spectra and the content of carbonates of the biochars suggested that carbonates were the major alkaline components in the biochars generated at the high temperature; they were also responsible for the strong buffer plateau-regions on the acid-base titration curves at 500 and 700°C. The data of FTIR-PAS and zeta potentials indicated that the functional groups such as -COO(-) (-COOH) and -O(-) (-OH) contained by the biochars contributed greatly to the alkalinity of the biochar samples tested, especially for those generated at the lower temperature. These functional groups were also responsible for the negative charges of the biochars.
Pyrolysis is the anaerobic thermal conversion of biomass for energy production. It offers an option of returning carbon and nutrients to the soil while producing energy. The Ultisols in the southeastern United States have inherently low soil organic carbon and fertility, and may benefit from the addition of biochar from pyrolysis. Our objectives were to evaluate the effect of peanut hull and pine chip biochars on soil nutrients, corn (Zea mays L.) nutrient status and yield in a Kandiudult for two growing seasons (2006 and 2007). Experiments for each biochar source were conducted as completely randomized designs with the biochar applied at 0, 11, and 22 Mg ha-1 with and without N fertilizer. Nitrogen in the peanut hull biochar (209 kg ha-1 at 11 Mg ha-1 rate) was not available during the study based on corn tissue concentrations. The peanut hull biochar linearly increased Mehlich I K, Ca, and Mg in the surface soil (0-15 cm). The increased available K was reflected in the plant tissue analysis at corn stage R1 in 2006, but not in 2007. Pine chip biochar decreased soil pH, but had no effect on other nutrients except Mehlich I Ca. In the peanut hull biochar experiment, grain yields decreased at the 22 Mg ha-1 rate in the fertilized treatments. In the pine chip biochar experiment, grain yields decreased linearly with application rate in 2006, but this did not persist in 2007. Overall yield responses to biochar were smaller than expected based on previous studies.
The carbon (C) cycle in boreal regions is strongly influenced by fire, which converts biomass and detrital C mainly to gaseous forms (CO<sub>2</sub> and smaller proportions of CO and CH<sub>4</sub>), and some 1–3% of mass to pyrogenic C (PyC). PyC is mainly produced as solid charred residues, including visually-defined charcoal, and a black carbon (BC) fraction chemically defined by its resistance to laboratory oxidation, plus much lower proportions of volatile soot and polycyclic aromatic hydrocarbons (PAHs). All PyC is characterized by fused aromatic rings, but varying in cluster sizes, and presence of other elements (N, O) and functional groups. The range of PyC structures is often described as a continuum from partially charred plant materials, to charcoal, soot and ultimately graphite which is formed by the combination of heat and pressure. There are several reasons for current interest in defining more precisely the role of PyC in the C cycle of boreal regions. First, PyC is largely resistant to decomposition, and therefore contributes to very stable C pools in soils and sediments. Second, it influences soil processes, mainly through its sorption properties and cation exchange capacity, and third, soot aerosols absorb solar radiation and may contribute to global warming. However, there are large gaps in the basic information needed to address these topics. While charcoal is commonly defined by visual criteria, analytical methods for BC are mainly based on various measures of oxidation resistance, or on yield of benzenepolycarboxylic acids. These methods are still being developed, and capture different fractions of the PyC structural continuum. There are few quantitative reports of PyC production and stocks in boreal forests (essentially none for boreal peatlands), and results are difficult to compare due to varying experimental goals and methods, as well as inconsistent terminology. There are almost no direct field measurements of BC aerosol production from boreal wildfires, and little direct information on rates and mechanisms for PyC loss. Structural characterization of charred biomass and forest floor from wildfires generally indicates a low level of thermal alteration, with the bulk of the material having H/C ratios still >0.2, and small aromatic cluster sizes. Especially for the more oxidation-resistant BC fraction, a variety of mainly circumstantial evidence suggests very slow decomposition, with turnover on a millennial timescale (in the order of 5–7 ky), also dependent on environmental conditions. However, there is also evidence that some PyC may be lost in only tens to hundreds of years due to a combination of lower thermal alteration and environmental protection. The potential for long-term PyC storage in soil may also be limited by its consumption by subsequent fires. Degraded, functionalized PyC is also incorporated into humified soil organic matter, and is transported eventually to marine sediments in dissolved and particulate form. Boreal production is estimated as 7–17 Tg BC y<sup>−1</sup> of solid residues and 2–2.5 Tg BC y<sup>−1</sup> as aerosols, compared to global estimates of 40–240 and 10–30 Tg BC y<sup>−1</sup>, respectively. Primary research needs include basic field data on PyC production and stocks in boreal forests and peatlands, suitable to support C budget modeling, and development of standardized analytical methods and of improved approaches to assess the chemical recalcitrance of typical chars from boreal wildfires. To accomplish these goals effectively will require much greater emphasis on interdisciplinary cooperation.
The use of biomass to provide energy has been fundamental to the development of civilisation. In recent times pressures on the global environment have led to calls for an increased use of renewable energy sources, in lieu of fossil fuels. Biomass is one potential source of renewable energy and the conversion of plant material into a suitable form of energy, usually electricity or as a fuel for an internal combustion engine, can be achieved using a number of different routes, each with specific pros and cons. A brief review of the main conversion processes is presented, with specific regard to the production of a fuel suitable for spark ignition gas engines.
Sorption behavior of hydrophobic organic contaminants (HOCs) (i.e., pyrene, phenanthrene and naphthalene) by native and chemically modified biopolymers (lignin, chitin and cellulose) was examined. Lignins (native and treated) showed nonlinear sorption for all compounds studied, emphasizing their glassy character. Chitins and celluloses had linear isotherms for phenanthrene and naphthalene, illustrating the dominance of partitioning, while pyrene yielded nonlinear isotherms. Sorption capacity (K(oc)) of HOCs was negatively correlated with the polarity [(O+N)/C] of the biopolymers. Aromatic and alkyl+aromatic C percentages, rather than alkyl C content, demonstrated a better correlation with K(oc) values, indicating the importance of aromatic structures for HOC affinity. Hydrophobicity (K(ow))-normalized K(oc) values decreased sharply with increasing percentage of O-alkyl C versus total aliphatic C (O-alkyl C/total aliphatic C) or with polar C/(alkyl+aromatic C) ratio of the biopolymers until their values reached 80% and 4, respectively, illustrating the effect of surrounding polar groups on reducing affinity for HOCs. Overall, the results of this study highlight the role of spatial arrangement of domains within biopolymers in sorption of HOCs, and point to sorbent properties, such as functionality, polarity and structure, jointly regulating the sorption of HOCs in biopolymers.
Pyrolysis of biomass for hydrogen fuel and bio-oil produces a char byproduct. There is evidence that land application of char may increase soil water holding capacity and the ability of the soil to retain nu- trients. Increases in these soil characteristics could be beneficial to plant growth as well as improving water quality. Chars produced under different conditions and from different feedstocks have different characteristics. Of the common feedstocks tested, peanut hull char con- tained higher nutrients and had a higher cation ex- change capacity than pine chip, pine bark, or hardwood chip chars. Preliminary moisture release curve data from a Tifton loamy sand indicated moisture holding capacity may be increased at very high rates of char addition. Soil moisture was periodically measured dur- ing the growing season in a field study of microplots amended with peanut hull and pine chip pellet char. Although the average soil water content of the plots amended at 22 Mg ha -1 was higher than the control, dif- ferences in volumetric water content were only signifi- cant on one date.
Some soil samples were collected from Rungicherra Tea-Estate of Moulvibazar district, Bangladesh. Active acidity, reserve acidity, cation exchange capacity and clay content of the collected soil samples were determined. The measured parameters of the soil samples were plotted and analyzed with reference to site and topography. The parameters have been found to vary with sampling sites, depths and topography.
The potential of vacuum pyrolysis to convert sugar cane bagasse into char materials for wastewater treatment and soil amendment is the focus of this research paper. Vacuum pyrolysis produces both bio-oil and char in similar quantities. Vacuum pyrolysis has the potential to produce high quality chars for wastewater treatment and soil amendment directly during the conversion process, with no further upgrading required. In the present study, chars with the required porous structure was obtained directly from the vacuum pyrolysis process, making it very efficient as adsorbent both in terms of methylene blue (MB) adsorption with a N2-BET surface area of 418 m2 g−1. Further steam activation of the chars benefited the development of meso- and macroporosity, although this upgrading step was not essential to achieve the required performance of char as an MB adsorbent. The development of large pores during the vacuum pyrolysis favored physisorption of MB, rather than chemisorption. The chemical nature of the vacuum pyrolysis char resulted in a slightly acidic surface (pH 6.56). The biochar from vacuum pyrolysis can be considered as a highly beneficial soil amendment, as it would enhance soil nutrient and water holding capacity, due to its high cation exchange capacity (122 cmolc kg−1) and high surface area. It is also a good source of beneficial plant macro- and micronutrients and contains negligible levels of toxic elements.
Investigations for the utilization of olive stones and solvent-extracted olive pulp are carried out. Tar, solid and gas products are obtained by pyrolysis of both precursors under vacuum and atmospheric pressure. Vacuum pyrolysis causes a decrease in the solid yield and an increase in the liquid and gas yields. The identified compounds of the liquid products are predominantly oxygen-containing structures (derivatives of phenol, dihydroxybenzenes, guaiacol, syringol, vanilin, veratrol, furan, acids). Activated carbons with a developed porous structure and alkaline character of the surface are produced by steam activation of the solid product and steam pyrolysis of the raw material. Oxidation treatment with air leads to the formation of a large number of oxygen functional groups with different chemical characters on the carbon surface. Chemical activation with K2CO3 allows the preparing of carbon adsorbents with a high surface area and alkaline character of the surface.
Experimental results for slow and vacuum pyrolysis of sugar cane bagasse, in the same reactor allowing the comparison of these two processes, are reported. The experimental results showed that vacuum pyrolysis leads to a higher BET specific surface area whereas slow pyrolysis seemed to favour the HHV of charcoal. Detailed yields of products are presented and the influence of temperature and heating rate were studied using a design of experiments and an ANOVA analysis. From the results the optimum experimental conditions to maximise the yields of char and bio-oil products, as well as their heating value and specific surface area characteristics, were established.The optimal yields of bio-oil for vacuum pyrolysis were obtained at 400–500 °C and a heating rate of 15–24 °C min−1, and for char the corresponding values are 340–350 °C and 18–24 °C min−1. Slow pyrolysis produced the highest char yield. The optimal ranges of temperature and heating rate differ from that of vacuum pyrolysis mainly due to the short residence time of the vapours in the case of vacuum pyrolysis.Optimum conditions for bio-oil and char yields did not correspond with conditions to optimize the BET surface and HHV for chars, and to minimize the water content of the products.
The present work reports a theoretical study of the infrared spectra of chemical structures that are suitable to the description of the surface chemistry of carbon materials. Prior to any consideration, the computational approach was tested and adapted by comparing the predicted IR spectra to those obtained experimentally for various reference compounds. Several models were considered, subsequently accounting for the most relevant functional groups that have been postulated to decorate the edges of graphene layers on carbon materials (i.e., anhydrides, carboxyls, lactones, phenolic, quinones, and pyrones). For each of the previous functional groups, different structures involving a different number of fused rings were considered. This strategy allowed us to establish the effect of conjugation on the shift of the IR frequencies corresponding to a given functional group. Cooperative effects between different functional groups (phenol-carboxyl, phenol-lactone, and so on) were another aspect that revealed itself to be an interesting issue when assigning frequencies in the IR spectra of highly oxidized carbon materials. Thus, it was found that the frequencies of the C=O bonds present in acid functional groups were systematically lowered when phenolic groups were close enough to establish hydrogen bonds. Special attention was also paid to the elucidation of the origin of the 1600-cm(-1) band of carbons. It was found that, in the case of acid carbons, this band can be assigned to C=C stretching of carbon rings decorated mainly with phenolic groups. Cyclic ethers in basic carbons would also promote absorption in the 1600-cm(-1) region of the IR spectrum. Finally, the predicted assignments are employed to interpret the IR spectra obtained experimentally for several activated carbons.
Thermochemical processing of biomass produces a solid product containing char (mostly carbon) and ash. This char can be combusted for heat and power, gasified, activated for adsorption applications, or applied to soils as a soil amendment and carbon sequestration agent. The most advantageous use of a given char depends on its physical and chemical characteristics, although the relationship of char properties to these applications is not well understood. Chars from fast pyrolysis and gasification of switchgrass and corn stover were characterized by proximate analysis, CHNS elemental analysis, Brunauer-Emmet-Teller (BET) surface area, particle density, higher heating value (HHV), scanning electron microscopy, X-ray fluorescence ash content analysis, Fourier transform infrared spectroscopy using a photo-acoustic detector (FTIR-PAS), and quantitative 13C nuclear magnetic resonance spectroscopy (NMR) using direct polarization and magic angle spinning. Chars from the same feedstocks produced under slow pyrolysis conditions, and a commercial hardwood charcoal, were also characterized. Switchgrass and corn stover chars were found to have high ash content (32–55 wt %), much of which was silica. BET surface areas were low (7–50 m2/g) and HHVs ranged from 13 to 21 kJ/kg. The aromaticities from NMR, ranging between 81 and 94%, appeared to increase with reaction time. A pronounced decrease in aromatic CH functionality between slow pyrolysis and gasification chars was observed in NMR and FTIR-PAS spectra. NMR estimates of fused aromatic ring cluster size showed fast and slow pyrolysis chars to be similar (∼7–8 rings per cluster), while higher-temperature gasification char was much more condensed (∼17 rings per cluster). © 2009 American Institute of Chemical Engineers Environ Prog, 2009
Sugarcane is grown in different countries since the middle of 19th century, primarily for the production of sugar. It was only after the Global Energy crisis of 1973, that the scientists' and technologists' realized the value of sugarcane, its byproducts and co-products. Today, sugarcane is considered as one of the best converter of solar energy into biomass and sugar. The biomass which contains fiber, lignin, pentosans and pith can be converted into value added products by application of suitable chemical, biochemical and microbial technologies. Sugarcane is a versatile crop being a rich source of food (sucrose, jaggery and syrups), fiber (cellulose), fodder (green leaves and tops of cane plant, bagasse, molasses and to some extent press mud),fuel and chemicals (bagasse, molasses and alcohol).Almost all the countries in the world which produce canesugar have realized that though the production of sugar from sugarcane is undoubtedly the most paying proposition, it is better to produce many value added products by diversification and utilizing the by-products of the sugar industry, instead of depending on just one product i.e. sugar(Paturau, 1982; Singh and Solomon, 1995; Godshall, 2004 ). The main by-products of the sugar industry which have greater economic value are: 1 Bagasse 2 Molasses 3 Filter Press Cake or Press Mud The sugar industry by-products are vast potential reserves for human and animal consumption as well as capable of providing energy as renewable source. The sugarcane and its by-products are useful raw material to over 25 industries; some important ones are shown in Table 1. Besides these byproducts, there are other products also which are of less commercial value, viz.,
The objective of this study was to provide background data on sugarcane bagasse vacuum pyrolysis. Product yields and properties were investigated. Vacuum pyrolysis tests were performed at bench and pilot plant scales. The bagasse finest particles with a diameter smaller than 450 μm were removed in order to overcome difficulties caused by their low density and high ash content. In comparison with the pyrolysis test carried out in the pilot reactor, the pyrolysis tests performed at the laboratory scale yielded more oil (34.4 vs. 30.1 wt.%) and less charcoal (19.4 vs. 25.7 wt.%). This bio-oil was found to be a potential valuable liquid fuel: it has a low ash content (0.05 wt.%), a relatively low viscosity (4.1 cSt at 90 °C), a high calorific value (22.4 MJ/kg) and a low content of methanol insoluble materials (0.4 wt.%). Accelerated ageing tests performed at 80 °C indicated that the bio-oil has a thermal susceptibility similar to oils obtained from other biomass materials. The charcoal, gas and aqueous phase were also characterized.
The use of activated carbon obtained from Euphorbia rigida for the removal of a basic textile dye, which is methylene blue, from aqueous solutions at various contact times, pHs and temperatures was investigated. The plant material was chemically modified with H2SO4. The surface area of chemically modified activated carbon was 741.2 m2 g−1. The surface characterization of both plant- and activated carbon was undertaken using FTIR spectroscopic technique. The adsorption process attains equilibrium within 60 min. The experimental data indicated that the adsorption isotherms are well described by the Langmuir equilibrium isotherm equation and the calculated adsorption capacity of activated carbon was 114.45 mg g−1 at 40° C. The adsorption kinetics of methylene blue obeys the pseudo-second-order kinetic model and also followed by the intraparticle diffusion model up to 60 min. The thermodynamic parameters such as ΔG°, ΔH° and ΔS° were calculated to estimate the nature of adsorption. The activation energy of the system was calculated as 55.51 kJ mol−1. According to these results, prepared activated carbon could be used as a low-cost adsorbent to compare with the commercial activated carbon for the removal textile dyes from textile wastewater processes.
Apricot stone, hazelnut shell, grapeseed and chestnut shell are important biomass residues obtained from the food processing industry in Turkey and they have a great importance as being a source of energy. In this study, the characteristics of bio-oil and biochar samples obtained from the carbonization of apricot stone, hazelnut shell, grapeseed and chestnut shell were investigated. It was found that the biochar products can be characterized as carbon rich, high heating value and relatively pollution-free potential solid biofuels. The bio-oil products were also presented as environmentally friendly green biofuel candidates.
A large number of solid-state NMR and ESR experiments were explored as potential tools to study chemical structure, mobility, and pore volume of activated carbon. We used a model system where pecan shells were activated with phosphoric acid, and carbonized at 450 °C for 4 h with varying amounts of air flow. Through the use of different NMR experiments (e.g., CP-MAS, SPE-MAS, and DD-MAS) several structural parameters were calculated such as mole fraction of bridgehead aromatic carbons, number of carbons per aromatic ring system, and number of phenolic carbons per aromatic ring system. The relaxation time measurements (T1, TCH, and ) were indicative of the relative mobility of different structural units. ESR spectra showed the presence of π-type aromatic free radicals in the carbonized samples with a slight shift in g value with increasing oxidation. The combined NMR and ESR data give a consistent picture of the carbon structure and the carbonization process, which is not easily available otherwise. In addition, the 1H NMR data on adsorbed water are shown to be consistent with the trends in the amount of pore volumes for different samples of activated carbons.
A review of the production of activated carbons from agricultural residues is presented. The effects of various process parameters on the pyrolysis stage are reviewed. Influences of activating conditions, physical and chemical, on the active carbon properties are discussed. Under certain process conditions several active carbons with BET surface areas, ranging between 250 and 2410 m2/g and pore volumes of 0.022 and 91.4 cm3/g, have been produced. A comparison in characteristics and uses of activated carbons from agricultural residues with those issued from tires, and commercial carbons, have been made. A review is carried out of the reaction kinetic modelling, applied to pyrolysis of agricultural wastes and activation of their pyrolytic char.
A review is given on the surface chemistry of carbon blacks and other carbons, in particular, activated carbons. The main part is devoted to surface oxides with emphasis on the chemical methods used in the assessment and identification of surface functional groups. Their formation under mild conditions and the influence of water vapor and metal catalysts on the reaction with air (“aging” of carbons) are described. Reaction with free organic radicals can be used for the functionalization of carbon surfaces.
While a large-scale soil amendment of biochars continues to receive interest for enhancing crop yields and to remediate contaminated sites, systematic study is lacking in how biochar properties translate into purported functions such as heavy metal sequestration. In this study, cottonseed hulls were pyrolyzed at five temperatures (200, 350, 500, 650, and 800 °C) and characterized for the yield, moisture, ash, volatile matter, and fixed carbon contents, elemental composition (CHNSO), BET surface area, pH, pHpzc, and by ATR-FTIR. The characterization results were compared with the literature values for additional source materials: grass, wood, pine needle, and broiler litter-derived biochars with and without post-treatments. At respective pyrolysis temperatures, cottonseed hull chars had ash content in between grass and wood chars, and significantly lower BET surface area in comparison to other plant source materials considered. The N:C ratio reached a maximum between 300 and 400 °C for all biomass sources considered, while the following trend in N:C ratio was maintained at each pyrolysis temperature: wood≪cottonseed hull≈grass≈pine needle≪broiler litter. To examine how biochar properties translate into its function as a heavy metal (NiII, CuII, PbII, and CdII) sorbent, a soil amendment study was conducted for acidic sandy loam Norfolk soil previously shown to have low heavy metal retention capacity. The results suggest that the properties attributable to the surface functional groups of biochars (volatile matter and oxygen contents and pHpzc) control the heavy metal sequestration ability in Norfolk soil, and biochar selection for soil amendment must be made case-by-case based on the biochar characteristics, soil property, and the target function.
Surface charge and pH-dependent nutrient release properties of cornstraw biochar were examined to elucidate its potential agronomic benefits. Kinetics of element release was characterized by rapid H(+) consumption and rapid, pH-dependent P, Ca, and Mg release, followed by zero-order H(+) consumption and mineral dissolution reactions. Initial K release was not pH-dependent, nor was it followed by a zero-order reaction at any pH. Rapid and constant rate P releases were significant, having the potential to substitute substantial proportions of P fertilizer. K releases were also significant and may replace conventional K fertilizers, however, not long-term plant demand. The cation exchange capacity (CEC) of the biochar leached with a mild acidic solution increased linearly from 179 to 888 mmol(c) (kg C)(-1) over a pH range of 4-8, while the anion exchange capacity of 154 mmol(c) (kg C)(-1) was constant over the same pH range. Since native soil organic constituents have much higher CEC values (average 2800 mmol(c) (kg C)(-1) at pH 7), improved soil fertility as a result of enhanced cation retention by the biochar probably will be favorable only in sandy and low organic matter soils, unless surface oxidation during aging significantly increases its CEC.
Through cation exchange capacity assay, nitrogen adsorption-desorption surface area measurements, scanning electron microscopic imaging, infrared spectra and elemental analyses, we characterized biochar materials produced from cornstover under two different pyrolysis conditions, fast pyrolysis at 450 °C and gasification at 700 °C. Our experimental results showed that the cation exchange capacity (CEC) of the fast-pyrolytic char is about twice as high as that of the gasification char as well as that of a standard soil sample. The CEC values correlate well with the increase in the ratios of the oxygen atoms to the carbon atoms (O:C ratios) in the biochar materials. The higher O:C ratio was consistent with the presence of more hydroxyl, carboxylate, and carbonyl groups in the fast pyrolysis char. These results show how control of biomass pyrolysis conditions can improve biochar properties for soil amendment and carbon sequestration. Since the CEC of the fast-pyrolytic cornstover char can be about double that of a standard soil sample, this type of biochar products would be suitable for improvement of soil properties such as CEC, and at the same time, can serve as a carbon sequestration agent.
Agricultural soils in the southeastern U.S. Coastal Plain region have meager soil fertility characteristics because of their sandy textures, acidic pH values, kaolinitic clays, low cation exchange capacities, and diminutive soil organic carbon contents. We hypothesized that biochar additions will help ameliorate some of these fertility problems. The study objectives were to determine the impact of pecan shell-based biochar additions on soil fertility characteristics and water leachate chemistry for a Norfolk loamy sand (fine-loamy, kaolinitic, thermic typic Kandiudults). Soil columns containing 0, 0.5, 1.0, and 2.0% (wt/wt) biochar were incubated at 10% (wt/wt) moisture for 67 days. On days 25 and 67, the columns were leached with 1.2 to 1.4 pore volumes of deionized H2O, and the leachate chemical composition determined. On days 0 and 67, soil samples were collected and analyzed for fertility. The biochar had a pH of 7.6, contained 834.2 and 3.41 g kg-1 of C and N, respectively, and was dominated by aromatic C (58%). After 67 days and two leaching events, biochar additions to the Norfolk soil increased soil pH, soil organic carbon, Ca, K, Mn, and P and decreased exchangeable acidity, S, and Zn. Biochar additions did not significantly increase soil cation exchange capacity. Leachates contained increasing electrical conductivity and K and Na concentrations, but decreasing levels of Ca, P, Mn, and Zn. These effects reflect the addition of elements and the higher sorption capacity of biochar for selective nutrients (especially Ca, P, Zn, and Mn). Biochar additions to the Norfolk soil caused significant fertility improvements.
This work presents agronomic values of a biochar produced from wastewater sludge through pyrolysis at a temperature of 550 degrees C. In order to investigate and quantify effects of wastewater sludge biochar on soil quality, growth, yield and bioavailability of metals in cherry tomatoes, pot experiments were carried out in a temperature controlled environment and under four different treatments consisting of control soil, soil with biochar; soil with biochar and fertiliser, and soil with fertiliser only. The soil used was chromosol and the applied wastewater sludge biochar was 10tha(-1). The results showed that the application of biochar improves the production of cherry tomatoes by 64% above the control soil conditions. The ability of biochar to increase the yield was attributed to the combined effect of increased nutrient availability (P and N) and improved soil chemical conditions upon amendment. The yield of cherry tomato production was found to be at its maximum when biochar was applied in combination with the fertiliser. Application of biochar was also found to significantly increase the soil electrical conductivity as well as phosphorus and nitrogen contents. Bioavailability of metals present in the biochar was found to be below the Australian maximum permitted concentrations for food.
Biomass pyrolysis with biochar returned to soil is a possible strategy for climate change mitigation and reducing fossil fuel consumption. Pyrolysis with biochar applied to soils results in four coproducts: long-term carbon (C) sequestration from stable C in the biochar, renewable energy generation, biochar as a soil amendment, and biomass waste management. Life cycle assessment was used to estimate the energy and climate change impacts and the economics of biochar systems. The feedstocks analyzed represent agricultural residues (corn stover), yard waste, and switchgrass energy crops. The net energy of the system is greatest with switchgrass (4899 MJ t(-1) dry feedstock). The net greenhouse gas (GHG) emissions for both stover and yard waste are negative, at -864 and -885 kg CO(2) equivalent (CO(2)e) emissions reductions per tonne dry feedstock, respectively. Of these total reductions, 62-66% are realized from C sequestration in the biochar. The switchgrass biochar-pyrolysis system can be a net GHG emitter (+36 kg CO(2)e t(-1) dry feedstock), depending on the accounting method for indirect land-use change impacts. The economic viability of the pyrolysis-biochar system is largely dependent on the costs of feedstock production, pyrolysis, and the value of C offsets. Biomass sources that have a need for waste management such as yard waste have the highest potential for economic profitability (+$69 t(-1) dry feedstock when CO(2)e emission reductions are valued at $80 t(-1) CO(2)e). The transportation distance for feedstock creates a significant hurdle to the economic profitability of biochar-pyrolysis systems. Biochar may at present only deliver climate change mitigation benefits and be financially viable as a distributed system using waste biomass.
Durian peel was used for the synthesis of activated carbon used for adsorption of Basic Green 4 dye. Activated carbon was synthesised under either nitrogen (N(2)) atmospheric or vacuum pyrolysis, followed by carbon dioxide (CO(2)) activation. The synthesised activated carbon then was treated with hydrochloric acid (HCl) solution. The results showed that activated carbon synthesised under vacuum pyrolysis exhibited better properties and adsorption capacities than that under nitrogen atmospheric pyrolysis. The HCl treatment improved properties and adsorption capacities of activated carbons. Pseudo-second-order kinetics well described the adsorption of Basic Green 4.
Black carbon (BC) is regarded as a chemically and biologically stable form of carbon and the changes of BC properties in nature are generally assumed to be minute. However, more and more observations have argued the inertness of BC. The objectives of this study were to characterize the changes of BC properties through ageing processes and to identify if these changes are associated with temperature. Our results showed that ageing of BC occurs over a temperature range from -22 degrees C to 70 degrees C within a short period of 12 months. The main changes of BC properties through ageing were found in elemental composition, surface chemistry, and adsorption properties, where the aged BCs were shown to have higher oxygen concentrations, surface acidity, and negative surface charge but lower C concentrations, pH, surface basicity, point of zero net charge, and also a lower adsorption capacity of hydroquinone, an allelopathic compound, than fresh BC. These ageing processes of BC were affected by temperature and changed over time, with higher temperature and longer incubation time enhancing BC ageing. Our results from a wide temperature range suggest that ageing of BC is likely to occur in any terrestrial regime and that the changes of BC properties through ageing should not be overlooked.
Wood industries and power plants generate enormous quantities of wood ash. Disposal in landfills has been for long a common method for removal. New regulations for conserving the environment have raised the costs of landfill disposal and added to the difficulties for acquiring new sites for disposal. Over a few decades a number of studies have been carried out on the utilization of wood ashes in agriculture and forestry as an alternative method for disposal. Because of their properties and their influence on soil chemistry the utilization of wood ashes is particularly suited for the fertility management of tropical acid soils and forest soils. This review principally focuses on ash from the wood industry and power plants and considers its physical, chemical and mineralogical characteristics, its effect on soil properties, on the availability of nutrient elements and on the growth and chemical composition of crops and trees, as well as its impact on the environment.
Cation exchange capacity, in: Methods of Soil Analysis, Part 2: Chemical and Microbial Properties
- J D Rhoades
J.D. Rhoades, Cation exchange capacity, in: Methods of Soil Analysis, Part 2:
Chemical and Microbial Properties, ASA and SSA, Madison, 1982.