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Sustainable Exploitation of Posidonia oceanica Balls through an Integrated Biorefinery Approach
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For the first time, an energy-efficient and eco-friendly technology for the conversion of abundantly available kitchen waste, specifically waste cooked rice water (WCRW) to drop-in- biofuels, namely, butyl levulinate (BL), has been explored. The synthesis of BL was accomplished employing butyl alcohol (BA) and WCRW in an energy-efficient UV (5W each UVA and UVB)-near-infrared (100W) irradiation assisted spinning (120 rpm) batch reactor (UVNIRSR) in the presence of TiO2-Amberlyst 15 (TA15) photo-acidic catalyst system (PACS). The optimal 95.81% yield of BL (YBL) could be achieved at 10 wt% catalyst concentration, 60 °C reaction temperature, 80 min time, and 1:10 WCRW: BA concentration as per Taguchi statistical design. Moreover, additional combination of different PACS such as TiO2-Amberlyst 16, TiO2-Amberlyst 36, and TiO2-Amberlite IRC120 H rendered 86.72% YBL, 90.04% YBL, and 93.47% YBL, respectively, proving superior efficacy compared to individual activity of the acidic catalysts and photocatalysts. The heterogeneous reaction kinetics study for TA15 PACS suggested Langmuir–Hinshelwood model to be the best fitted model. A significant 63.33% energy could be saved by UVNIRSR as compared to conventional heated reactor at the optimized experimental condition using PACS TA15. An overall alleviation in environmental pollution with 59.259% reduction in GWP, 15.254% decline in terrestrial ecotoxicity, 18.238% diminution in marine ecotoxicity, 17.25% decrease in ozone formation affecting human health, 5.865% reduction in human non-carcinogenic toxicity, 18.65% diminution in ozone formation affecting terrestrial ecosystem, 55.17% significant decrease in terrestrial acidification, and 25.619% mitigation in fresh water ecotoxicity could be observed. Furthermore, BL-biodiesel-diesel blends (3% BL, 7% biodiesel, and 90% diesel) exhibited significant reduction (25.45% and 36%, respectively, for CO and HC) in harmful engine exhaust emissions demonstrating environmental sustainability of the overall process.
Alkyl levulinates (ALs) are strategic compounds for the development of sustainable energy transition. In this regard, the direct alcoholysis of fructose and inulin for the selective ethyl levulinate (EL) production was investigated with a One‐Factor‐At‐a‐Time (OFAT) approach employing diluted H2SO4 as catalyst to clarify the role of the main reaction parameters (substrate and acid loadings, temperature, reaction time). The OFAT investigation on fructose ethanolysis allowed to reach the EL yield of 91.5 mol%. The inulin ethanolysis was then optimized adopting the multivariate approach based on the Response Surface Methodology (RSM), which highlighted the interplay of the reaction parameters on the selective EL production. This allowed to identify the optimal conditions to reach the highest EL yield (up to 89.3 mol%) and also those which ensured the highest EL concentration, adopting a substrate loading (14 wt%) higher than the majority ones reported in the literature according to the high gravity approach, and the lowest diethyl ether (DEE) by‐product yield. The DEE formation is scarcely investigated in the literature, but it can negatively influence the alcoholysis process, thus it was considered in this work. Moreover, the humin solid residue was deeply characterized to envisage its possible applications, under a circular economy perspective.
Deep Eutectic Solvents (DES) have emerged as an alternative for many applications in different chemical sectors (to be used during the upstream and downstream processing, or as performance additives). While traditionally coined as green solvents, the petrochemical and energy-demanding origin of some DES components, together with some reported toxicological data, have been often overlooked. This perspective discusses the possible fate of DES once they have been used as synthetic reaction media, particularly related to the downstream unit to recover the product from the reaction mixture, and to the final DES disposal. The Total Carbon Dioxide Release (TCR) (measured as kg CO2 per kg product) is used to compare different options. After a downstream processing to recover the product often involving an organic solvent which will be incinerated (producing CO2), the used DES media can either be incinerated or diluted to some degree to be divested to a Wastewater Treatment Plant (WWTP). A mild wastewater treatment – involving state-of-the-art microbial processing steps, appears more promising than the incineration option, both in terms of CO2 production, as well as to avoid the potential formation of halide compounds (e.g. from chloride) during the incineration. However, to reach the WWTP, a key factor is the dilution degree of the DES, and the biodegradability that DES (components) may display by wastewater microorganisms. At a range of 1 : 20 dilution, a production of ∼16 kg CO2 per kg product may be expected in the WWTP, for a synthesis in DES containing 100 g substrate loading per L. Research is urgently needed to assess whether the treatment of DES as diluted wastewater may be a sustainable (and economic) solution for the DES fate.
Posidonia oceanica balls (POB), a kind of seagrass, are a significant environmental issue since they are annually discharged onto beaches. Their current usefulness limits interest in their management and enhances the environmental problem. Therefore, in this research, the potential of this lignocellulosic biomass was studied from a holistic biorefinery point of view. To this end, an in-depth study was carried out to select the best pathway for the integral valorization of POBs. First, an autohydrolysis process was studied for the recovery of oligosaccharides. Then, a delignification stage was applied, where, in addition to studying different delignification methods, the influence of the autohydrolysis pre-treatment was also investigated. Finally, cellulose nanofibers (CNFs) were obtained through a chemo-mechanical treatment. The results showed that autohydrolysis not only improved the delignification process and its products, but also allowed the hemicelluloses to be valorized. Acetoformosolv delignification proved to be the most successful in terms of lignin and cellulose properties. However, alkaline delignification was able to extract the highest amount of lignin with low purity. CNFs were also successfully produced from bleached solids. Therefore, the potential of POB as a feedstock for a biorefinery was confirmed, and the pathway should be chosen according to the requirements of the desired end products.
The carbon reduction effect of bio-based levulinic acid chemicals is a matter of concern. This work reports the life cycle assessment of methyl levulinate based on local biomass refineries in China. The final LCA results showed that the entire life cycle of methyl levulinate could reduce by approximately 24% of carbon emissions compared with fossil diesel of equal quality. To address the lack of effective uncertainty analysis in current LCA research on levulinic acid chemicals, this study conducted a comprehensive and detailed assessment of inventory data and utilized Taylor series expansion to obtain uncertainty of the LCA results. When connected to a localized background database, the LCA results showed high credibility. According to the sensitivity analysis and Aspen optimization results, further technical improvement schemes are proposed, including improving thermal efficiency, use of clean electricity, and use of clean methanol. Prospective analysis shows that combined implementation of the above strategies can further reduce the existing carbon emissions by more than half.
Graphical Abstract
Posidonia oceanica (L.) Delile is the main seagrass plant in the Mediterranean basin that forms huge underwater meadows. Its leaves, when decomposed, are transported to the coasts, where they create huge banquettes that protect the beaches from sea erosion. Its roots and rhizome fragments, instead, aggregate into fibrous sea balls, called egagropili, that are shaped and accumulated by the waves along the shoreline. Their presence on the beach is generally disliked by tourists, and, thus, local communities commonly treat them as waste to remove and discard. Posidonia oceanica egagropili might represent a vegetable lignocellulose biomass to be valorized as a renewable substrate to produce added value molecules in biotechnological processes, as bio-absorbents in environmental decontamination, to prepare new bioplastics and biocomposites, or as insulating and reinforcement materials for construction and building. In this review, the structural characteristics, and the biological role of Posidonia oceanica egagropili are described, as well as their applications in different fields as reported in scientific papers published in recent years.
Research attempts on biomass use constitute a response to the growing demand for sustainable and low-cost energy from renewable sources. Hence, the sustainable use of Posidonia oceanica (PO) waste as a material for biomass to produce green energy is being considered in many countries in the Mediterranean region. PO meadows are considered as the main type of sea flora in the Greek coasts. PO can extract biomass from nearby ecosystems of the coastal zone, either directly through the transportation of disposed non-living leaves or indirectly via benthic organisms. The aim of this study is to investigate the use of PO waste derived from Kefalonia Island (Greece) as a biomass source. PO samples were collected around the island, and they were mineralogically and microstructurally analyzed. In addition, physicochemical, chemical, and thermogenic tests were performed in order to obtain the optimum and most completed characterization of the material. Based on the results, cellulose seems to be the main structural component of PO, which also seems to determine their behavior. PO presents microscopic similarities to other lignocellulosic materials which composition is made of carbonates, lignin, extractives, and minerals. Ash and moisture content constitute the two critical parameters that are responsible for the energy differences of each biomass. The outcome of this study shows the potential use of PO wastes as an interesting source for energy production.
Pre-treatment of biomass is a necessary step for delignification as well as an unavoidable step in the journey of biomass to biofuel. Apart from delignification, defragmentation and partial depolymerization of biomass are two other additional useful steps in the overall process of pre-treatment. Ultimately these three steps together make the downstream enzymatic hydrolysis process more effective in producing optimum total reducing sugar. Several different pre-treatment technologies are available to delignify various types of biomasses with each of them being unique concerning specific advantages and disadvantages, characteristics of its own. However, different pre-treatment methods, in combination, have been found beneficial with higher delignification efficiency in comparison to a single pre-treatment method, implemented on its own. Apart from physical pre-treatment procedures like milling, grinding, steam explosion, etc., pre-treatment methods can be divided, roughly, into three groups: biological pre-treatment, physical pre-treatment and chemical pre-treatment. Chemical pre-treatments always arrest significantly higher attention due to their effectiveness and minimum treatment time required. In this review, a thorough discussion of various chemical and biological pre-treatment technologies, along with their efficacy and effective outcomes, have been discussed in order to understand their impacts on bioenergy industries.
The Folin-Ciocalteu assay is a widely used method for measuring the total phenolic content (TPC) in honey, but it can be affected by the presence of reducing sugars in honey, which can lead to interference and an over-estimation of its TPC. To optimize the Folin-Ciocalteu assay for honey analysis, the effect of pH on the assay was investigated. A number of pH scenarios were tested using different concentrations of Na2CO3 (0.00%, 0.75%, 0.94%, and 7.50%) in order to minimize reducing sugar interference and maximize the reaction of phenolics in the assay. The modified TPC method was then validated in accordance with current International Council on Harmonisation (ICH) guidelines. The findings of this study demonstrate that the traditional Folin-Ciocalteu assay (using 7.50% aqueous Na2CO3 solution, pH 10.8) leads to a significant overestimation of the TPC of honey due to the interference of reducing sugars. However, a pH of 7.9, achieved by using a 0.75% aqueous Na2CO3 solution, provides suitable conditions to account for most of the phenolic compounds without interference from reducing sugars. This finding was further confirmed by testing various sugar solutions and artificial honey which yielded TPC values below the established limit of detection and quantification of the assay. However, a slight increase in pH, even by a moderate deviation (pH 8.9), leads to significant discrepancies in absorbance readings, indicating that pH control is crucial for the accurate analysis of TPC in honey.
This research studies in detail four different assays, namely DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2´-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)), FRAP (ferric ion reducing antioxidant potential) and FC (Folin-Ciocalteu), to determine the antioxidant capacity of standard substances as well as 50 organosolv lignins, and two kraft lignins. The coefficient of variation was determined for each method and was lowest for ABTS and highest for DPPH. The best correlation was found for FRAP and FC, which both rely on a single electron transfer mechanism. A good correlation between ABTS, FRAP and FC, respectively, could be observed, even though ABTS relies on a more complex reaction mechanism. The DPPH assay merely correlates with the others, implying that it reflects different antioxidative attributes due to a different reaction mechanism. Lignins obtained from paulownia and silphium have been investigated for the first time regarding their antioxidant capacity. Paulownia lignin is in the same range as beech wood lignin, while silphium lignin resembles wheat straw lignin. J o u r n a l P r e-p r o o f Journal Pre-proof 2 Miscanthus lignin is an exception from the grass lignins and possesses a significantly higher antioxidant capacity. All lignins possess a good antioxidant capacity and thus are promising candidates for various applications, e. g. as additives in food packaging or for biomedical purposes.
A low temperature alkali (LTA) pretreatment method was used to treat wheat straw. In order to obtain good results, different factors like temperature, incubation time, NaOH concentration and solid to liquid ratio for the pretreatment process were optimized. Wheat straw is a potential biomass for the production of monomeric sugars. The objective of the current study was to observe the saccharification (%) of wheat straw with immobilized magnetic nanoparticles (MNPs). For this purpose, immobilized MNPs of purified β-xylanase enzyme was used for hydrolysis of pretreated wheat straw. Wheat straw was pretreated using the LTA method and analyzed by SEM analysis. After completion of the saccharification process, saccharification% was calculated by using a DNS method. Scanning electron micrographs revealed that the hemicellulose, cellulose and lignin were partially removed and changes in the cell wall structure of the wheat straw had caused it to become deformed, increasing the specific surface area, so more fibers of the wheat straw were exposed to the immobilized β-xylanase enzyme after alkali pretreatment. The maximum saccharification potential of wheat straw was about 20.61% obtained after pretreatment with optimized conditions of 6% NaOH, 1/10 S/L, 30 °C and 72 hours. Our results indicate the reusability of the β-xylanase enzyme immobilized magnetic nanoparticles and showed a 15% residual activity after the 11th cycle. HPLC analysis of the enzyme-hydrolyzed filtrate also revealed the presence of sugars like xylose, arabinose, xylobiose, xylotriose and xylotetrose. The time duration of the pretreatment has an important effect on thermal energy consumption for the low-temperature alkali method.
This paper deals with the enhancement of thermal insulation of building construction materials by the incorporation of treated natural fibers (posidonia oceanica and esparto grass). The surface treatment of the natural fibers aimed at the improvement of the adhesion between fibers and construction material matrices. Untreated and treated posidonia oceanica and esparto grass fibers have been characterized through Fourier Transform Infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The obtained results indicated a clear change in the surface morphology, enhancement in the crystallinity, and modification in the chemical structure of the treated posidonia oceanica and esparto grass fibers in comparison with untreated fibers. Experimental investigations have been carried out to examine the effect of the incorporation of treated posidonia oceanica and esparto grass fibers on the interfacial adhesion with matrices, the compressive strength of cement and gypsum composite samples compared to those with untreated fibers and their thermal properties. Results indicated, on the one hand, an improvement of the interfacial adhesion and compressive strength of matrices filled with treated fibers compared to those filled with untreated fibers. On the other hand, results have shown a clear reduction in thermal diffusivity, thermal conductivity, and bulk density of composites with the addition of treated fibers compared to those of composites without fibers. Finally, the treated posidonia oceanica and esparto grass utilized can replace conventional synthetic fibers and will be an interesting alternative that would solve simultaneously environmental and energy concerns.
Bilge waters are wastewaters produced on boats during navigation and usually contain hydrocarbons and oils. They cannot be directly released into the sea if not below a hydrocarbons concentration limit set by current legislation. Appropriate oil in water separator (OWS) systems can be installed on board boats to remove hydrocarbons from bilge water allowing their spillage into the sea. These systems may contain an adsorption step on a suitable adsorbent. Here, biochars produced from pyrolysis of dead Posidonia oceanica, pristine or chemically activated, have been tested as hydrocarbons adsorbents. Adsorption experiments with aqueous dispersions simulating bilge waters containing a marine gas oil (MGO) fuel for boats, a surfactant, and different NaCl concentrations were carrying out. The hydrocarbons concentrations before and after adsorption have been directly measured by using the reverse phase HPLC technique coupled with a fluorescence detector. These measurements are very fast and their reliability was verified by re-measuring the hydrocarbons concentrations of some samples with the GC–MS-MS technique, according to one of the traditional methods for hydrocarbons determination in emulsions. Different isotherm equations were used to fit the adsorption data. The biochars were characterized from the chemical-structural point of view by means of several instrumental techniques.
The presence of antibiotics as micro-contaminants in the water and aqueous environments is a health concern to humans and the ecosystem. Therefore, their elimination by adsorption to available and cheap materials in water treatment plants is a research topic of high relevance. The present paper reports on the adsorption behavior of oxytetracycline on a bio-adsorbent prepared from Posidonia oceanica; an abundant Mediterranean biomass. Characterization of the pretreated Posidonia biomaterial was achieved using several analyses such as Boehm acid–base titration method, pHPZC determination, and analysis techniques (FTIR, ¹³C CP-MAS NMR, optical microscopy, and TGA). The pHPZC occurred around pH 2.11. Posidonia biomaterial showed a fast and high uptake rate throughout the adsorption process, which is a definite advantage for analytical applications such as water decontamination. The experimental kinetic data fitted very rightly the pseudo-second-order kinetic model and the equilibrium uptake can adopt the bi-Langmuir isotherm model for all studied pH values which assumes adsorptions at the two localized sites. Maximum adsorption capacities of 11.8 mg∙g⁻¹ and 4.4 mg∙g⁻¹ for the two adsorption sites are reached at pH 6. The oxytetracycline adsorption process onto Posidonia bio-adsorbent is spontaneous (ΔadsG⁰ < 0), exothermic (ΔadsH⁰ < 0), and entropically favorable (ΔadsS⁰ > 0). The effect of pH on adsorption behavior and the thermodynamic parameters of adsorption are consistent with a possible origin of adsorption of oxytetracycline by means of hydrogen bonding interactions between surface hydroxyl and phenolic groups of the biomaterial and oxytetracycline. The proposed green and environmentally friendly biomaterial offers potential benefits as a bio-adsorbent in the remediation of aquatic environments contaminated by various organic materials.
Graphical abstract
Every year, millions of tonnes of dead biomass from algae and seagrasses are collected on the Mediterranean coasts. Posidonia oceanica is one of the most abundant species. In this work, leaves and rhizomes from this plant were pulped, alkalized, and cationized to make a value-added product. The main effects of five separate pulping variables, namely temperature, time, NaOH concentration, anthraquinone, and liquid-to-solid ratio were studied. The total procedure to produce cationic fibers took only 3 h (approximately), which made it a feasible process. A pseudo-second-order rate equation was used to fit the results of chemical modification via incorporation of quaternary ammonium ions. Characterization involved X-ray diffraction, scanning electron microscopy, and elemental analysis. The authors found that mild conditions were enough to achieve good results, reaching degrees of substitution of 0.20 for leaves and 0.12 for rhizomes.
Hydrolysis and butanolysis of lignocellulosic biomass are efficient routes to produce two valuable bio-based platform chemicals, levulinic acid and n-butyl levulinate, which find increasing applications in the field of biofuels and for the synthesis of intermediates for chemical and pharmaceutical industries, food additives, surfactants, solvents and polymers. In this research, the acid-catalyzed hydrolysis of the waste residue of Cynara cardunculus L. (cardoon), remaining after seed removal for oil exploitation, was investigated. The cardoon residue was employed as-received and after a steam-explosion treatment which causes an enrichment in cellulose. The effects of the main reaction parameters, such as catalyst type and loading, reaction time, temperature and heating methodology, on the hydrolysis process were assessed. Levulinic acid molar yields up to about 50 mol % with levulinic acid concentrations of 62.1 g/L were reached. Moreover, the one-pot butanolysis of the steam-exploded cardoon with the bio-alcohol n-butanol was investigated, demonstrating the direct production of n-butyl levulinate with good yield, up to 42.5 mol %. These results demonstrate that such residual biomass represent a promising feedstock for the sustainable production of levulinic acid and n-butyl levulinate, opening the way to the complete exploitation of this crop.
UV/visible light is a promising radiation source for biomass pretreatment, but very little knowledge is available on the effect of UV on the thermal behavior of lignocellulose in comparison with more classical, physical pretreatment methods. In this paper, we investigate the effects of ball-milling and UV irradiation on two species of softwood and two species of hardwood, using X-ray diffractometry (XRD), evolved gas analysis-mass spectrometry (EGA-MS), and pyrolysis-gas chromatography coupled to mass spectrometry (Py-GC/MS). The XRD data showed that the crystalline fraction of cellulose was destroyed by milling, but not by irradiation. The EGA-MS data and isoconversional kinetic analysis showed that both milling and irradiation can reduce the thermal stability of wood up to a limit value. The Py-GC/MS data showed that irradiation caused the most significant changes in the pyrolytic behavior of the wood species, increasing the ratio of holocellulose to lignin pyrolysis products and the reactivity of cellulose toward the derivatizing agent. Softwoods were more affected by irradiation than hardwoods. This paper shows that UV irradiation can decrease the recalcitrance of biomass toward pyrolysis, but its efficiency is highly dependent on the type of lignocellulosic substrate.
Alkyl levulinates (ALs) represent outstanding bio-fuels and strategic bio-products within the context of the marketing of levulinic acid derivatives. However, their synthesis by acid-catalyzed esterification of pure levulinic acid, or by acid-catalyzed alcoholysis of furfuryl alcohol, although relatively simple, is still economically disadvantageous, due to the high costs of the pure precursors. The direct one-pot alcoholysis of model C6 carbohydrates and raw biomass represents an alternative approach for the one-step synthesis of ALs. In order to promote the market for these bio-products and, concurrently, the immediate development of new applications, it is necessary to speed up the intensification of their production processes, and this important achievement is onlypossible by using low-cost or, even better, waste biomasses, as starting feedstocks. This review provides an overview of the most recent and promising advances on the one-pot production of ALs from model C6 carbohydrates and real biomasses, in the presence of homogeneous or heterogeneous acid catalysts. The use of model C6 carbohydrates allows for the identification of the best obtainable ALs yields, resulting in being strategic for the development of new smart catalysts, whose chemical properties must be properly tuned, taking into account the involved reaction mechanism. On the other hand, the transition to the real biomass now represents a necessary choice for allowing the next ALs production on a larger scale. The improvement of the available synthetic strategies, the use of raw materials and the development of new applications for ALs will contribute to develop more intensified, greener, and sustainable processes.
Lignins from different parts of the seagrass Posidonia oceanica –namely sheaths, rhizomes, and roots– as well as from fibrous balls from P. oceanica detritus were isolated and thoroughly characterized by Pyrolysis coupled with Gas Chromatography/Mass Spectrometry (Py-GC/MS), Derivatization Followed by Reductive Cleavage (DFRC), two-dimensional Nuclear Magnetic Resonance (2D-NMR) spectroscopy, and Gel Permeation Chromatography (GPC). The lignins of P. oceanica were enriched in guaiacyl (G) over syringyl (S) units, with S/G ratios ranging from 0.1 (fibrous balls) to 0.5 (rhizome). β–O–4ʹ ethers and phenylcoumarans were the most abundant lignin substructures, followed by resinols, and minor amounts of dibenzodioxocins and spirodienones. Moreover, all lignins were found to be highly γ-acylated (up to 44% of total units), mainly with p-hydroxybenzoates but also, to a lesser extent, with acetates. The data indicated that this acylation extensively occurred in both G- and S-lignin units, contrary to what happens in palms, poplar and willow, where p-hydroxybenzoates overwhelmingly appear at the γ-position of S-units.
Lignin is the by-product of pulp and paper industries and bio-refining operations. It is available as the leading natural phenolic biopolymer in the market. It has chromophore functional groups and can absorb a broad spectrum of UV light in range of 250–400 nm. Using lignin as a natural ingredient in sunscreen cream, transparent film, paints, varnishes and microorganism protection has been actively investigated. Both in non-modified and modified forms, lignin provides enhancing UV protection of commercial products with less than a 10% blend with other material. In mixtures with other synthetic UV blockers, lignin indicated synergic effects and increased final UV blocking potential in compare with using only synthetic UV blocker or lignin. However, using lignin as a UV blocker is also challenging due to its complex structure, polydispersity in molecular weight, brownish color and some impurities that require more research in order to make it an ideal bio-based UV blocker.
The present investigation represents a concrete example of complete valorization of Eucalyptus nitens biomass, in the framework of the circular economy. Autohydrolyzed-delignified Eucalyptus nitens was employed as a cheap cellulose-rich feedstock in the direct alcoholysis to n-butyl levulinate, adopting n-butanol as green reagent/reaction medium, very dilute sulfuric acid as a homogeneous catalyst, and different heating systems. The effect of the main reaction parameters to give n-butyl levulinate was investigated to check the feasibility of this reaction and identify the coarse ranges of the main operating variables of greater relevance. High n-butyl levulinate molar yields (35–40 mol%) were achieved under microwave and traditional heating, even using a very high biomass loading (20 wt%), an eligible aspect from the perspective of the high gravity approach. The possibility of reprocessing the reaction mixture deriving from the optimized experiment by the addition of fresh biomass was evaluated, achieving the maximum n-butyl levulinate concentration of about 85 g/L after only one microwave reprocessing of the mother liquor, the highest value hitherto reported starting from real biomass. The alcoholysis reaction was further optimized by Response Surface Methodology, setting a Face-Centered Central Composite Design, which was experimentally validated at the optimal operating conditions for the n-butyl levulinate production. Finally, a preliminary study of diesel engine performances and emissions for a model mixture with analogous composition to that produced from the butanolysis reaction was performed, confirming its potential application as an additive for diesel fuel, without separation of each component.
Milled wood lignin (MWL) was isolated from Dendrocalamus sinicus, an abundant bamboo variety in the earth, using Bjorkman method. Elucidation and quantification of the chemical structures for the isolated MWL have been facilitated by employing FT-IR and NMR techniques. The obtained results showed that the MWL consists of syringyl (S), guaiacyl (G), and p-hydroxyphenyl (H) units, indicating it as grass type (HGS) lignin. There is no significant change in structure (i.e. cleavage at α-O-4′ and β-O-4′ linkage) was observed. NMR techniques indicated that the isolated lignin was rich in β-O-4′ aryl ether substructures and syringyl (S) units. Furthermore, the sufficient understanding of the chemical structure of the lignin benefits their effective utilization towards the production of renewable biomass and biofuels.
Butyl levulinate (BL) is a versatile chemical utilized widely in food and chemical industries, the production of which by using cellulose in biomass resources is of great significance to its sustainable development. Traditional synthesis processes for n-butyl levulinate are confronted with various problems such as high cost of raw materials, difficulty in separating products, etc. In this paper, a novel process for the preparation of BL from cellulose is proposed. The process is composed of five main unit operations including fed-batch hydrolysis, decolorization, extraction, esterification and purification. A 171.63 g/L concentration of the intermediate levulinic acid was obtained at the fifth feeding through the fed-batch hydrolysis process. The resin-activated carbon secondary decolorization method was adopted to remove the soluble humin byproducts with an accumulative decolorization rate of 89%. In the extraction process, the product BL was chosen as the extractant to avoid the introduction of new impurities. After purification, the purity of the final product BL reaches up to 98 wt %. The proposed technique allows for cost-effective and eco-friendly production of BL from biomass resources.
The aim of the conducted research was to obtain information on the main components of ashes from 35 biomass species used in combustion processes to obtain reference data for the development of utility possibilities for these ashes, with particular emphasis on agricultural use. The examined biomass samples were divided into groups depending on origin: woody biomass and energetic woody plants I-WWB, herbaceous and grassy energy plants II-EC, agricultural waste III-AR, forest waste IV-FR and waste from the agri-food industry V-AFIW. The analysis of the studied elements contents was carried out in the designated groups. The chemical composition of ash was dominated by the macroelements Ca, K, P and S, which suggests the possibility of their agricultural use. At the same time, the low content of toxic elements such as As and Pb should not be a limiting feature in their use, with the exception of wood biomass. In addition, ashes obtained from the biomass combustion were enriched with microelements such as Zn, Cu and Mn, which further increases their possibilities of fertilizer use. The potential use of ash from each type of biomass in the aspect of its chemical composition should be considered individually, regardless of the division into groups depending on the origin of biomass.
The growing interest in substituting synthetic products coming from non-renewable sources with products from biomass has focused attention on the lignin biopolymer. Its high availability, low price and properties make the development of new and valuable uses for lignin interesting, thus improving the economic and environmental aspects of the biomass conversion. To achieve this objective, the potential use of industrial kraft and organosolv lignins as antioxidants, antimicrobials and sunscreen products has been evaluated. The results of a detailed antibacterial and antifungal study demonstrated the high potential of kraft lignins against a variety of foodborne and human pathogenic microorganisms. Moreover, both organosolv and kraft lignins presented an effective protection factor (SPF values from 10–20), demonstrating their effectiveness as natural additives for the sun lotion market. In addition, lignin samples presented high antioxidant capacity compared to butylated hydroxytoluene (BHT), one common commercial antioxidant industrially used. Therefore, the development of innovative applications of lignins as a commodity for the chemical, pharmaceutical or cosmetic industries could expand their possible uses in the market giving new added values to lignin.
The antioxidant properties of technical lignins have been extensively investigated but there are still gaps of knowledge that should be filled to facilitate the practical applications of lignins as antioxidants (AOs). In the present investigation, we compared the short-term (60 min) and long-term (48h) AO performance of lignins with different contents of functional groups and lignin model compounds (LMCs) with different aromatic ring substituents in the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH*) antioxidant assay. We found some LMCs to quickly expend their AO capacity while others started off slowly but after 48h had consumed more DPPH* per phenolic hydroxyl group. Reaction time was also a factor in the relative AO performance of lignins. For softwood lignins, a higher phenolic hydroxyl content was associated with increased DPPH* reactivity. CatLignin, a thermally treated lignin rich in phenolic units and especially catechol groups, consumed more than twice as much DPPH* than any other lignin during 48h (over two mol/lignin unit of 180 g/mol). CatLignin also had the lowest 60 min half-maximal effective concentration (EC50). In polypropylene, lignins provided better UV protection than commercial primary antioxidants applied at similar loadings. Similarly, the better performance of lignin over commercial AOs was observed against thermal oxidation.
Due to the severe waste plastics pollution issues, fabricating biodegradable films as substitutes for plastic has been a pursuit of modern scientists for the past few years. UV (Ultraviolet) shielding...
Saccharum ravannae, known as "Ekra" in the Northeast region of India, is an elephant grass species that abundantly grows in the natural habitat of Assam. This study aims to utilize this wild grass species and extract alkaline lignin of high purity through KOH-mediated alkaline hydrothermal pretreatment using the Oil bath process. Lignin recovery was optimized using RSM (response surface methodology) combined with a central composite model. Three process parameters, namely KOH concentration (1-3 %), reaction time (50-200 min), and solid loading (5-15 %), varied to optimize the combined effect of these parameters. RSM predicted a maximum lignin recovery of 15.38 g/100 g of raw biomass at optimum conditions (2.4 % KOH, 6.41 % solid loading, 176.57 min). Three experimental runs were performed at optimum conditions, and 15.81 ± 0.32 g/100 g lignin recovery was obtained, thus verifying the predicted result. Maximum 93.7 % purity of extracted lignin was achieved in a different operating condition (3 % KOH, 10 % solid loading, 125 min). The commercial and extracted alkaline lignin with maximum purity was characterized by Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The extracted lignin shows higher phenolic content and more functional groups than commercial lignin and can be used for future applications.
Increasing efforts have been devoted to the production of bio-based chemicals from high solid content of renewable biomass to pursue optimal process efficiency and economics. In this study, the preparation of methyl levulinate (ML) by metal sulfate-catalyzed methanolysis from high solid content of cellulose was investigated. When the cellulose loading was 15%, 38.67% of ML yield can be obtained under the optimum reaction conditions. Al2(SO4)3 can be reused more than five times while maintaining high activity in the process. The characterization of cellulose particles confirmed that cellulose particles shrunk over the reaction time. The heterogeneous degradation kinetics of high solid content of cellulose in methanol could be explained by a shrinking core model. High solid loadings led to a decrease of the reaction rate constants of methanolysis. Using cellulose with a small particle size can improve the methanolysis reaction rate. The study also proposed comprehensive reaction pathways for ML production from high solid content of cellulose. To elucidate the methanolysis mechanism, an assessment of density functional theories for the calculation of glucose methanolysis at the molecular level is presented. All these results can inspire the development of ML synthesis technology through methanolysis from renewable biomass with high solid loadings.
Lithium-Sulfur Batteries is promising energy storage systems due to their superior capacity and energy density. A promising solution for drawbacks such as low sulfur utilization and cycling stability is the use of porous carbon as sulfur carrier. On the other hand, cyclic economy and green ideas is of great importance nowadays. Carbon-sulfur cathodes from waste valorization, abundant, and low-cost precursors is an attractive approach. Herein, an activated carbon (AC-Poc) derived from “Posidonia oceanica” sea-waste, was studied as a matrix for the development of a novel carbon–sulfur composite cathode (AC-Poc/S) for the first time. AC-Poc can be used as an effective sulfur host, due to its high specific BET surface area (1264 m²∙g⁻¹) hierarchical porous structure, and total pore volume 0.81 cm³∙g⁻¹. AC-Poc/S reveals an outstanding initial capacity of 1539 mAh∙g⁻¹ as cathode material, combined with high reversible capacity at 0.2 C. Furthermore, the discharge capacity of 390 mAh/g at 2 C reveals good rate capability, even at increased C-rate. AC-Poc/S composite exhibits excellent sulfur utilization (92 %) alongside with sufficiently well electrochemical performance. These results combined with the easy synthesis method of the activated carbon from an abundant and low-cost precursor make AC-Poc/S a very promising material for LSBs applications.
The use of alkyl levulinates is growing interest in fuels. Adding n-butyl levulinate (BL) to fuels presents some benefits compared to ethyl levulinate. The conventional production route of BL is from the esterification of levulinic acid, but the latter compound presents some corrosion issues. Alcoholysis of fructose by butanol over cation exchange resins (solid catalyst) seems to be a better alternative. The effect of water addition, solvent, swelling effect (from the cation exchange resin), and fructose solubility at temperatures higher than 25 °C are unclear on this reaction. To understand these effects, the alcoholysis of fructose by butanol at 110 °C in different solvents, e.g., gamma-valerolactone (GVL), were studied in a pressurized autoclave in an inert environment. The dissolution study was conducted in a temperature range of 20–120 °C in different solvents. The concentration profiles of fructose, 5-(hydroxymethyl)furfural (HMF), 5-(butoxymethyl)furfural (BMF) and BL were analyzed in different solvents: butanol/water, butanol, butanol/GVL/water and butanol/GVL. We found that using a butanol/GVL (70/30 wt%) solvent is better from the conversion and dissolution viewpoints.
As an abundant aromatic biopolymer, lignin has the potential to produce various chemicals, biofuels of interest through biorefinery activities and is expected to benefit the future circular economy. However, lignin valorization is hindered by a series of constraints such as heterogeneous polymeric nature, intrinsic recalcitrance, strong smell, dark colour, challenges in lignocelluloses fractionation and the presence of high bond dissociation enthalpies in its functional groups etc. Nowadays, industrial lignin is mostly combusted for electricity production and the recycling of inorganic compounds involved in the pulping process. Given the research and development on lignin valorization in recent years, important applications such as lignin-based hydrogels, surfactants, three-dimensional printing materials, electrodes and production of fine chemicals have been systematically reviewed. Finally, this review highlights the main constraints affecting industrial lignin valorization, possible solutions and future perspectives, in the light of its abundance and its potential applications reported in the scientific literature.
Microwave (MW)-assisted heating is one of the emerging technologies for biomass conversion into energy, fuels, and chemicals. It is claimed to be energy efficient, time-saving, and improves throughput compared to conventional processing systems mainly due to its unique heating nature. Yet, the issues hindering the scale-up of MW biomass processing technology has not been discussed much in the open literature. Previous review articles have mainly focused on the pyrolysis process parameters and product yields. This paper aims to present the challenges faced to scale-up the MW technology for biomass processing. The effects of materials’ dielectric properties and penetration depth, MW hotspots and non-thermal effects, MW absorbers and catalysts, temperature, sample size, retention time and MW power on product characteristics are addressed in detail. Importantly, energy analysis, batch vs continuous MW operation, and reactor/cavity design are presented to advance the scale-up of MW technology for processing a wide variety of biomass wastes. The article also covers different biomass thermo-chemical processes such as pyrolysis, gasification, liquefaction and torrefaction.
This paper presents a bio-based process for the catalytic conversion of cellulose to ethyl levulinate and an analysis of its techno-economic feasibility. The said bio-based process relies as major feedstock on cellulose, which can be derived from lignocellulosic biomass. cellulose is converted to ethyl levulinate via a homogeneous catalytic reaction whereby dilute sulfuric acid in combination with Al salts is the catalyst and ethanol is the solvent and reactant. This approach affords high ethyl levulinate yields but requires complex procedures for used catalyst and solvent recycling. Based on experimental results on the homogeneous catalytic reaction and vapor–liquid equilibrium separation in the previous studies, a simulation was conducted that included process design, energy integration, and economic analysis. Results from this simulation indicated the proposed bio-based process to afford a minimum selling price of US$ 2,830 per ton of ethyl levulinate, which was highly dependent on an off-site supply of heating energy required for ethanol purification.
In recent years, biofuels have been attracting more attention, especially in Europe, due to the new regulations concerning the improvement of renewables in fuel composition.
The acid-catalysed alcoholysis reaction of the cellulosic fraction of raw and pre-treated lignocellulosic biomasses, using n-Butanol (n-BuOH) and diluted inorganic acid as homogeneous catalyst, produces a mixture mainly composed by Butyl Levulinate (BL) from cellulose, Dibutyl ether (DBE) from n-BuOH etherification and unreacted n-BuOH. This last can be then separated and recycled, so increasing the sustainability of the whole process.
BL is directly obtained from cellulosic fraction of not edible biomass and represents a promising advanced biofuel. Therefore, in the different types of blends containing the main products obtainable from the one-pot alcoholysis of lignocellulosic biomasses, BL represents the effective renewable component of the fuel.
In this work, different blends of BL/DBE mixed with Diesel fuel were tested in a small single-cylinder air-cooled Diesel engine with direct injection. Data concerning the measurement of pollutant emission, engine performance and combustion characteristics are reported. Results have been compared with those obtained fuelling the engine with a conventional Diesel fuel. The mixtures were prepared by using commercial reactants, characterized by compositions analogous to those of the reaction mixtures. The obtained results evidenced the potentiality of these novel blending mixtures to reduce the emissions of particulate without any increasing of NOx emission or changing in engine power and efficiency.
Lignin is a promising UV-shielding material to substitute the synthetic absorbers in a composite due to its excellent UV-shielding property. The chromophores group of lignin is responsible for the UV-shielding property of composites, but it brings an undesirable dark color. This perspective is the first to review the recent progress on fabricating light-colored UV-shielding composites that contain lignin; we provide a clear picture of the concept of light-colored UV-absorbing lignin composite materials that can be used in food packaging, healthcare products, and solar panel protection. The UV-absorbing and photostability mechanisms are introduced by correlating UV absorption with intrinsic factors, like phenolic substructures and molecular weight of lignin. Extrinsic factors that affect the UV-shielding properties and color of lignin, such as the extraction process, chemical modification method, and obtained size of lignin, are also systematically discussed in this perspective. By summarizing recent studies on the synergetic effect between the lignin and the second constitute materials, this perspective discusses the benefits of lignin to the composite’s overall properties, such as stability under UV radiation, mechanical property, dispersity, and water permeability.
Each year, sugarcane bagasse, a low-priced by-product of the sugar industry, is generated in large quantities. The aim of this study was to optimize the alkaline hydrolysis condition for the extraction of lignin from sugarcane bagasse using response surface methodology combined with Box-Behnken design, and to evaluate functional properties of lignin extracts for cosmetic applications. Three process parameters were varied (NaOH solution concentrations (3–7% w/v), temperatures (115–135 °C), and times (30–60 min)). The second-order polynomial model developed and the subsequent ANOVA test showed that the optimal conditions providing the highest total phenolic content (69.41 ± 0.32 mg gallic acid equivalent/g extract), antioxidant activity (262.30 ± 2.98 mg Trolox equivalent/g extract), and sun protection factor (8.65 ± 0.21) were as follows: NaOH solution concentration of 7% w/v, temperature of 135 °C, and time of 47.92 min. Fourier-transform infrared spectroscopy analysis revealed the functional groups present in the lignin extract that affected its activities. The extract showed both UVA and UVB-absorbing properties and tyrosinase-inhibitory properties. The results suggested that the lignin extract obtained from alkaline hydrolysis of sugarcane bagasse has great potential as a bioactive multi-functional ingredient that can offer anti-ageing, sun-protection, and skin-whitening properties for sun care formulations.
Finding renewable and green resources for nanomaterial preparation is a compelling topic concerning the sustainability in nanotechnological applications. In particular, lignin-based nanoparticles are pivotal for unlocking the use of lignin in value added products. In this paper, we isolated pure lignin (ca. 98 % of purity) from elephant grass (Pennisetum purpureum) using two simple extractions with diluted acid and alkali solutions and prepared lignin and lignin acetate nanoparticles dispersed in water-basis by anti-solvent addition. Elephant grass in natura contains ca. 25 % of lignin, which could be converted into lignin nanoparticles with a 37 % yield. Spherical lignin and lignin acetate nanoparticles were revealed by electron microscopies (TEM and FESEM) and proved to be stable in a wide pH range (5–11) and ionic strength lower than 0.01. Lignin nanoparticles showed higher antioxidant activity (RSI of ca. 82) as compared to lignin in solution and to the commercial antioxidants (BHT and BHA). These nanoparticles were successfully incorporated in a neutral cream, resulting in a tinted sunscreen formulation with both ultraviolet and visible absorption. Altogether, we present here an effective method to isolate pure lignin from a non-food biomass and to prepare stable and highly antioxidant lignin nanoparticles that can be applied in dermocosmetics and are intrinsically non-toxic to the environment.
This study presents a sustainable pathway for fractionating corn stover to produce glucose, high-quality lignin nano-particles (LNPs) and levulinic acid (LA) based on the use of p-toluenesulfonic acid (p-TsOH), a solvent having strong acidity and surface activity at high concentration. Under the moderate pretreatment temperature (100°C), 85% of xylose, 88% of arabinose and 83% of lignin were removed from the substrate, and present in the hydrolysate, while the cellulose yield in the solid residue fraction was 93%. The cellulose fraction exhibited much reduced “biomass recalcitrance”, and was readily enzyme-hydrolyzed, with its glucose yield reaching up to 93% at a high solid concentration of 15% (w/w). The hydrolysate, involving p-TsOH catalyst, was recycled for further hydrolysis of fresh corn stover: after four times hydrolysate recycling, the cellulose fraction still had a high glucose yield of 81%. The lignin fraction in the hydrolysate was utilized in the form of LNPs, which were prepared as a result of diluting the recycled hydrolysate. The as-prepared LNPs were spherical and uniform, with an average particle size of 147 nm. The application of LNPs in the preparation of chitosan film significantly improved its strength. After LNPs preparation, the diluent containing monomeric sugars were directly heated to 180 °C to produce LA in the presence of p-TsOH (an effective catalyst) with LA yield of 57.1%. The LA was easily separated from spent acid based on methyl isobutyl ketone (MIBK) extraction and the p-TsOH/ water mixture was recycled in the process.
Process mass intensity (PMI) is a key mass-based metric to evaluate the green credentials of an individual or sequence of reactions during process and chemical development. The increasing awareness to consider greenness already at the initial discovery level, requires a set of parameters suitable to assess it at this stage of development, and guidelines to apply them correctly. This paper evaluates when and how PMI can be used in a correct manner. Different simulations for key reactions in the organic synthesis toolbox - i.e. amide bond formation and Mitsunobu reactions – illustrate that PMI can be easily misleading without a due consideration of yield, concentration and molecular weight of reactants and product. A fair appraisal of the green potential of different methodologies therefore requires careful analysis of the examples and metrics data generated.
Posidonia oceanica brown algae (POBA) represent an abundant and renewable biomass in Algerian seas. In the present study, the POBA were chemically treated through delignification and alkali treatment followed by acid hydrolysis to produce pure microcrystalline cellulose (MCC). FTIR analysis indicates that most lignin and hemicellulose were eliminated during the chemical treatments. The XRD measurements revealed that the obtained cellulose and MCC belong to cellulose I polymorph, with crystallinity index of 60.50% and 74.23%, respectively. SEM micrographs of the produced MCC showed a non-uniform micro sized rod-like shape morphology with an average diameter of 8.4 ± 2.1 μm. The thermal analysis results exhibited that the decomposition temperature of the prepared MCC shifted to higher temperature compared to that of the respective cellulose and raw POBA. The authenticity of the prepared MCC was also examined by comparing its physicochemical properties with those of commercial MCC. Based on these analyses, POBA-MCC showed tremendous potential to be used in several applications.
UV degradation of wood is an important phenomenon that entails loss of aesthetic and mechanic properties. The changes are usually studied with artificial ageing followed by spectroscopy, and focus on colour changes. Analytical pyrolysis coupled with gas chromatography-mass spectrometry (Py-GC/MS) and evolved gas analysis-mass spectrometry (EGA-MS) are powerful tools for wood characterisation, but the change in pyrolytic behaviour of wood after UV irradiation is not well documented. In this work, a new instrumental setup was used to perform UV irradiation on line with EGA-MS and Py-GC/MS with in situ derivatisation of fir and chestnut wood. The effect of UV exposure was evaluated in terms of thermal stability and composition of the pyrolysate. TThe results showed that UV degradation of the samples was mainly related to the lignin fraction, and significant differences were observed between the two species. Fir wood, showed extensive degradation after 4 hours of irradiation, while chestnut wood, showed very small changes. Qualitative comparison of the EGA-MS profiles and semi-quantitative analyses of the composition of the pyrolysates revealed that these techniques could be used as a fast monitoring tool to assess the UV degradation of wood.
Lignin nanoparticles offer a way for a high value use of the renewable resources. However, there is few green and facile method so far for producing lignin nanoparticles with both high yield and regular shape. In this study, lignin was firstly modified through a microwave acetylation process without any catalysts and solvents other than acetic anhydride, which acted as both reaction reagent and dispersion solvent. Subsequently, the regular lignin nanoparticles with a high yield were prepared by a solvent shifting combined ultrasound process. The lignin nanoparticles were rapidly formed without dialysis and easily separated by centrifugation, meanwhile, the used THF could be recycled and reused, which would simplify the process, reduce the cost, and realize the industrial scale-up production. The highest yield of lignin nanoparticles reached to 82.3% as the lignin initial concentration and the ultrasound intensity increased. Meanwhile, the ultrasound treatment improved the uniformity and dispersion of the nanoparticles. The structure transformation and the forming mechanism of lignin nanoparticles were investigate through various techniques. Furthermore, the UV absorbing ability of lignin nanoparticles was examined. In a more general plan, it was confirmed that the green chemistry principles could be realized in the development of more sustainable lignin nanomaterials with various potential applications.
During the last decades, the demand for sustainable and renewable resources has greatly increased. It is clear that biomass exploitation in general, and lignin in particular, will play a key role toward a sustainable and environmental prosperous society. Lignin is a three-dimensional amorphous polymer, mainly found in the cell wall of woody tree species, quite abundant and renewable natural bioresource capable to become in the near future a usual chemical feedstock for many materials of added value. However, its physicochemical understanding is still poor in comparison to other polymers, most likely due to its complexity. Its dissolution, as an often required first step for several production processes and applications, is typically complicated. Nevertheless, a wide variety of solvents for lignin have already been developed and, among them, organic solvents, ionic liquids and deep eutectic solvents are particularly relevant. In this brief treatise, the general features of lignin dissolution are reviewed as the drawbacks and virtues of lignin solvents and appropriate dissolution conditions.
The first green chemistry metrics - the E factor (kgs waste / kg product) and atom economy (mol wt of product / sum of mol wts of starting materials) - were introduced in the early 1990s and were actually green chemistry avant la lettre. In the last two decades these two metrics have been adopted world-wide by both academia and industry. The E factor has been refined, to distinguish between simple and complete E factors, for example, and to define the system boundaries. Other mass-based metrics such as process mass intensity (PMI) and reaction mass efficiency (RME) have been proposed. However, mass-based metrics need to be augmented by metrics which measure the environmental impact of waste, such as life cycle assessment (LCA), and metrics for assessing the economic viability of products and processes. The application of such metrics in measuring the sustainability of processes for the manufacture of pharmaceuticals and other fine chemicals is discussed in detail. Mass-based metrics alone are not sufficient to measure the greenness and sustainability of processes for the conversion of renewable biomass vs fossil-based feedstocks. Various metrics for use in assessing sustainability of the manufacture of basic chemicals from renewable biomass are discussed. The development of a sustainable bio-based production of chemicals meshes well with the concept of a circular economy, based on resource efficiency and waste minimization by design, to replace traditional linear, take-make-use-dispose economies. KEYWORDS: E factor, Atom economy, Carbon economy, Step economy, Circular economy, Bio-based economy, Ethanol equivalent, Life cycle assessment