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Comparison of soybean hull pre-treatments to obtain cellulose and chemical derivatives: Physical chemistry characterization
Abstract
The cellulose from soybean hull, a waste without value from the argentine agriculture, was successfully obtained by using two different treatments: the traditional alkaline-bleaching pathway and from a simple pre-alkaline treatment at low temperatures. The comparison of both methods yielded similar results regarding its ability to open the lignin cellulosic structure of the hull and the total elimination of the lignin content. Fourier Transform Infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM), ¹³C nuclear magnetic resonance (¹³C-RMN) and Raman spectroscopy were used to characterize the structures and the properties of cellulose. The results showed that cellulose can be easily obtained with just an alkaline pre-treatment of 5% (w/v) NaOH during 40 h at 50 °C and free of any lignin content. The attachment of different functional groups, such as -COOH and (CH3)3N⁺, changed the physicochemical properties of the obtained cellulose, showing mayor crystalline structure, and consequently modifying the swelling capacity and its ability to adsorb model proteins.
... Soybean hulls holds a high cellulose content (40%) (Camiscia et al., 2018), and its utilization as a raw material could be of interest to the paper industry. With large-scale production of paper made from soybean hulls, there would be a reduction in the quantity of imported paper reels and fiber pulp, whose values range between 600 and 900 US$/t (Dirección Nacional de Aduanas [ADUANAS] 2019, Banco Central del Paraguay [BCP] 2019, Veritrade 2020). ...
... Soybean hulls occupy 2 to 8% of soybean seed and have 30 to 50% cellulose (Merci et al. 2019). This residue stands out among others for its low amount of lignin, making it possible to obtain pure cellulose through more economical chemical conditions and less harmful to the environment (Camiscia et al. 2018). The chemical composition of soybean hulls is compared with other lignocellulosic materials in Table 1 (Cassales et al. 2011;Carvajal et al. 2016;González et al. 2016;Merci et al. 2019 The percentages in the chemical composition shown were extracted from Merci et al. (2019) and correspond to soybean hulls imported from Brazil. ...
... The procedure performed by Camiscia et al. (2018) (Figure 1) allowed a yield of 41 ± 6% of the initial hulls weight in cellulose. ...
In Paraguay, the opportunity to use soybean hulls in paper production stands out thanks to its cellulose content (around 40%). Therefore, the most economically convenient process has been identified in this work providing an estimatedcost per tonne of paper pulp obtained from soybean hulls, in order to be installed in paper industries seeking to expandtheir product portfolio. The methodology adopted was based on a bibliographic review that allowed the theoreticalanalysis of soybean hulls characteristics as a raw material in paper production and the analysis of cellulose extractionprocesses from agro-industrial waste. Using only 6% of the total soybean hulls produced in the country in one year(203,566 t), a profit of US 775/t, making its economic valuehigher when it’s used in paper production than in exportation or animal feeding.
... The pH at zero electrical charge point (pH Z = 0) value for SBH was determined as previously reported (Camiscia et al., 2018;Fiol & Villaescusa, 2009). Briefly, 0.5 g of SBH and 10 mL of 10 mM KNO 3 were mixed in different falcon tubes. ...
... Raw SBH (Fig. 3a) shows an irregular surface, which comes from its highly fibrous structure which makes it highly permeable to water and small molecules, increasing its adsorption properties compared to other hulls. In a previous work, we have reported that the contact of SBH with an aqueous phase induces loss of soluble polysaccharides (xylan and pectin), leaving the cellulose fiber chains exposed (Camiscia et al., 2018). This is observed in Fig. 3b and c, where one can see the cellulose fibers arranged in parallel and are exposed to the attack of the dye molecules tested. ...
... All FT-IR spectra were normalized to the intensity of the mode that appears at 1050 cm −1 , only for a better comparison between the spectra. In Fig. 4a, the highest absorption band is viewed in the spectrum at the region of 1800-1450 cm −1 which is related to aromatic skeletal vibration and C=O stretching, corresponding to the lignin content (Camiscia et al., 2018), and also could involve signals corresponding to carboxylic acid and amides, probably due to the presence of proteins. Both dyes loaded on SBH ( Fig. 4b and c) show similar behavior at the region between 3715 and 3050 cm −1 . ...
The main objective of this work is to use soybean hull (SBH) waste as an adsorbent for the removal of two industrial textile dyes: Reactive Blue 21 (RB21) and Reactive Yellow 145 (RY145). Physical characterization of SBH and kinetic and equilibrium experiments were performed to determine the adsorption conditions. The best adsorption condition was pH 2.0 because the zero electrical charge of soybean hulls (pHZ = 0) is 5.27; thus, in an acidic pH, the adsorbent is positively charged, and the dyes keep their anionic charges due to the –SO3− and –OSO3− groups. Kinetic data were better represented by the Elovich kinetic model, evidencing two well-differentiated mass transfer regions, which agrees with a pseudo-second-order kinetic mechanism. The experimental data showed that RB21 and RY145 were fitted with Hill and Redlich–Peterson isotherm models, respectively. Consequently, the maximum adsorption capacities of SBH for RB21 and RY145 dyes were 149 mg/g and 87 mg/g, respectively. Dye adsorption in packed bed column was also assayed at different bed heights, flow rates, and inlet concentration of dyes. The Thomas, Yoon–Nelson, and modified dose-response (MDR) models fitted well to the breakthrough curves, the MDR model being the one with the highest correlation coefficients, with 96.5% and 94.4% removal of RY145 and RB21 dyes, respectively.
... On the other hand, soybean processing generates a by-product known as SBH, consisting of the seed coat of soybeans. SBH is typically removed during soybean processing operations and is often wasted, burned, or used as livestock feed (approximately 15-25 %) [3][4][5]. SBH is advantageous due to its high cellulose content. Typical SBH composition includes approximately 40-55 % cellulose, 16-18 % hemicelluloses, 13-17 % pectin, 8-14 % proteins, and 1-6 % lignin [6]. ...
... Various applications constantly explore new uses for agro-industrial wastes, and several studies have demonstrated the potential of SBH as an adsorbent [3,5] or as a precursor for MCC production [7]. Cellulose, being one of the most abundant biopolymers in nature, can be transformed into valuable products with significant economic value. ...
... ATR-FTIR measurements for all the analyzed samples mainly showed the typical signals of cellulose (see the spectra of some selected powders with the related attributions in Supplementary Information and Figure S2) (Yang et al. 2007(Yang et al. , 2017. The sufficient degree of cellulose isolation from SBH-A at the expense of other components is confirmed by the absence of the peak at 1745 cm −1 , which is related to either the acetyl and uronic ester groups of the hemicelluloses or the ester linkage of the carboxylic group of the ferulic and p-coumaric acids of lignin and/ or hemicellulose (Camiscia et al. 2018). This peak, indeed, is visible in Fig. S1, in the spectra of SBH-A and SBH-A after HCl treatment. ...
... Therefore, cationic antimicrobial agents, such as amino-based compounds, trigger the inactivation pathway from the adhesion and puncture to the negatively-charged membrane of bacteria (Arora and Mishra 2018;Luo et al. 2022), leading to its destabilization and eventually inducing microorganisms' death. Given these premises, if we consider only the cellulosic component of the isolated product from SBH-A, we cannot point out either peculiarity in the surface charge of bare W-cellulose (negative) (Camiscia et al. 2018;Tummino et al. 2020;Luo et al. 2022) or its changes in hydrophilicity with respect to the reference cellulose (F), only on the basis of the type of acid-base treatment employed for the isolation and the results of chemical analyses. What could occur is the role of W-cellulose as a passive polymeric layer, which was able to prevent the adhesion of bacteria by decreasing the protein adsorption on its surface, thereby repelling the bacteria without actively interacting with it (Arora and Mishra 2018). ...
Soybean hulls (SBHs) are one of the main by-products of soybean crushing, usually destined for animal feeding or to become a putrescible waste. In this work, we upgraded the SBHs to materials with antimicrobial properties. After the extraction of soybean peroxidase from SBHs, an enzyme applicable in different technological sectors and naturally present in soybean hulls, the exhausted biomass was subjected to an acid–base treatment to isolate cellulose. The obtained material was, in turn, functionalized with 3-aminopropyl triethoxysilane (APTES) to achieve new hybrids with antimicrobial properties. The synthetic procedure was optimized by varying the solvent type (ethanol or toluene) and APTES amount. Overall, the amino-functionalization process was effective and the activity was outstanding against both gram-positive and gram-negative bacteria, reaching complete disinfection practically in all cases. The samples were studied by means of several characterization techniques, demonstrating that the solvent and cellulose types had a significant influence on the physical–chemical features, together with the eco-sustainability of the process. In particular, the use of greener ethanol and waste cellulose (with respect to a commercial one) resulted in a higher APTES immobilization efficiency and superior thermal stability of the final materials. Interestingly, the presence of various unremoved compounds from the lignocellulosic SBH matrix, although in small quantities, emerged as a crucial factor, also in terms of antibacterial activity, hypothesizing a role of residual phytochemicals.
... It is also a source of polyphenols with antioxidant activity [17]. Despite its potential, soy hull is partly used as animal feed, mainly for dairy cattle, discarded as agricultural waste or burned, causing considerable disposal costs and negative environmental issues [17,18]. Little attention is given to its potential use as a food ingredient, especially for human consumption [13,18]. ...
... Despite its potential, soy hull is partly used as animal feed, mainly for dairy cattle, discarded as agricultural waste or burned, causing considerable disposal costs and negative environmental issues [17,18]. Little attention is given to its potential use as a food ingredient, especially for human consumption [13,18]. ...
This study aimed at developing a probiotic fermented soymilk-based dessert containing coffee and soybean hull. Nine fermented formulations were elaborated with 10% powdered soymilk (w/v), varying percentages of sugar, arabica soluble coffee, and soy hull. They were fermented with probiotic strains of Lactobacilli and Bifidobacteria (10 6 CFU/mL). One hundred and twenty-nine adults from Rio de Janeiro/RJ and Curitiba/PR, Brazil, evaluated the acceptance of the formulated products. The final formulation was physicochemically characterized. During 6h fermentation, the probiotics count increased from 10 6 to 10 8 in both strains. The well-accepted formulation contained 15% sucrose, 1% soy hull, and 0.5 or 1.5 % soluble coffee (score: 6.6±1.5 on a 9-point-scale). Alternatively, sucrose can be replaced by other types of sweeteners. Young people (n=45) who drank 2-4 cups of coffee per day liked the product the most (score: 7.1±1.4). While fermentation did not affect the total soy isoflavones content, it decreased the content of coffee chlorogenic acids by 32.6% but produced bioavailable phenolic acids as metabolites. A decrease in the content of flatus-producing oligosaccharides was also observed. In conclusion, probiotics fermentation and the addition of arabica soluble coffee made possible the development of a well-accepted and potentially healthy beany-flavor-free, dairy-free, pudding-like dessert.
... In addition, it breaks the ester bonds, which are present between the carbohydrate fractions and the lignin, resulting in a high solubilization of the lignin fraction (Shah et al., 2022). Alkaline pretreatments with the use of sodium hydroxide were applied to different agro-industrial by-products such as SH, SB, OPEFB and CPH, showing very similar results, with an enrichment of cellulose content and a decrease in amorphous fractions (Camiscia et al., 2018; Hernández-Mendoza et al., 2021;Nieves et al., 2011;Zhang et al., 2020). ...
... As it can be seen, the degree of extraction of the amorphous fraction, which is composed of lignin and hemicellulose, increases with respect to pretreatment's severity. When higher pretreatment conditions are applied, mainly temperature, a higher degree of extraction of the amorphous fraction is obtained (Camiscia et al., 2018;Valladares-Diestra et al., 2022b). Also, for the evaluated biomasses at, a severity factor greater than 3.5, it is possible to extract more than 50 % of the amorphous fraction. ...
Lignocellulosic biomass is a renewable material of great abundance. However, its recalcitrant characteristic requires the application of pretreatments. Sugarcane bagasse (SB), soybean hulls (SH), cocoa pod husks (CPH) and oil palm empty fruit bunches (OPEFB) were subjected to imidazole pretreatment in order to evaluate chemical composition variations and influence over enzymatic hydrolysis efficiency. Non-treated SH, SB and OPEFB have higher content of holocellulose, while CPH is rich in lignin polymers (31.2%). After imidazole-pretreatment, all biomasses presented structural disorganization of lignocellulosic fibres and enrichment in the percentage of cellulose. Levels of up to 72% delignification were obtained, which allowed an enzymatic conversion greater than 95% for SB, SH and OPEFB, while only 83% was reached for CPH. Imidazole is then emerging as a potential catalyst for the pretreatment of agro-industrial by-products, allowing the valorisation of these residues and their reinsertion into the production chain under a biorefinery concept.
... Soybean hulls have been also considered as source of carbon (obtained by either thermal or chemical transformations) for the production of micro-mesoporous adsorbents (Girgis et al., 2011), biofillers (Balint et al., 2020), and can potentially be employed in those fields where carbons are required as active substrates for electrochemistry, electronics and biomedicine (Thiha et al., 2019;Sun et al., 2020;Wang C. et al., 2020). Finally, also cellulose and other polysaccharides, constituting the lignocellulosic hull biomass and obtained after proper extraction processes (Camiscia et al., 2018;Wang S. et al., 2020), can find outlet in different branches of biotechnology (food, medicine, bioremediation, paper industry, etc.) and of biorefinery, since they can be converted to biopolymers, bioethanol or even to fuels with high commercial value (Cassales et al., 2011;Camiscia et al., 2018;Dall Cortivo et al., 2020;Wang S. et al., 2020). ...
... Soybean hulls have been also considered as source of carbon (obtained by either thermal or chemical transformations) for the production of micro-mesoporous adsorbents (Girgis et al., 2011), biofillers (Balint et al., 2020), and can potentially be employed in those fields where carbons are required as active substrates for electrochemistry, electronics and biomedicine (Thiha et al., 2019;Sun et al., 2020;Wang C. et al., 2020). Finally, also cellulose and other polysaccharides, constituting the lignocellulosic hull biomass and obtained after proper extraction processes (Camiscia et al., 2018;Wang S. et al., 2020), can find outlet in different branches of biotechnology (food, medicine, bioremediation, paper industry, etc.) and of biorefinery, since they can be converted to biopolymers, bioethanol or even to fuels with high commercial value (Cassales et al., 2011;Camiscia et al., 2018;Dall Cortivo et al., 2020;Wang S. et al., 2020). ...
Soybean hulls are one of the by-products of soybean crushing and find application mainly in the animal feed sector. Nevertheless, soybean hulls have been already exploited as source of peroxidase (soybean peroxidase, SBP), an enzyme adopted in a wide range of applications such as bioremediation and wastewater treatment, biocatalysis, diagnostic tests, therapeutics and biosensors. In this work, the soybean hulls after the SBP extraction, destined to become a putrescible waste, were recovered and employed as adsorbents for water remediation due to their cellulose-based composition. They were studied from a physicochemical point of view using different characterization techniques and applied for the adsorption of five inorganic ions [Fe(III), Al(III), Cr(III), Ni(II), and Mn(II)] in different aqueous matrixes. The behavior of the exhausted soybean hulls was compared to pristine hulls, demonstrating better performances as pollutant adsorbents despite significant changes in their features, especially in terms of surface morphology, charge and composition. Overall, this work evidences that these kinds of double-recovered scraps are an effective and sustainable alternative for metal contaminants removal from water.
... Another part is burned in furnaces at the industrial plants and used as an energy source through the generation of vapor [4]. However, most of the hull material produced is burned as waste or left in inappropriate places causing environmental problems [5]. ...
... The application of different methods of extraction can provide similar results; however, one which offers technical viability has to be selected. Camiscia et al. [5] compared two methods of cellulose extraction from soybean hulls at low temperatures. They showed similar results in relation to their capability for extracting cellulose and totally eliminating the lignin content. ...
Soybean hulls, a co-product generated in high volumes, were used to obtain pulp and CMC. The pulping process was optimized with the aid of 1%, 2%, and 2.5% NaOH solutions at 90 °C for 2 h. A 22 central composite design was used in order to optimize the bleaching process and the CMC synthesis. Volumes of bleaching solution (VS) of between 55 and 65 mL/g at temperatures between 85 and 95 °C and VS of 70 and 75 mL/g at 95 °C were applied in the pulp bleaching process. The factors considered in the carboxymethylation were the chloroacetic acid mass (1.2-2.1 g/g) and the reaction time (192-228 min), at 63 °C. The soybean hulls contain 40.62% of cellulose and have a low lignin content. The pulping process was optimized when 1% NaOH was used at 90 °C/2 h and bleaching process applying VS = 75 mL at 95 °C/4 h. The pulps showed low lignin content (<6%) and the cellulose had a high degree of crystallinity. The SEM, 1H NMR, XRD, FTIR and TGA/DTG analysis results demonstrated that it is possible to synthesize CMC (DS = 1.45) by acetylating the bleached pulp with 2.1 g of chloroacetic acid for 192 min, at 63 °C.
... The increase in the degradation of the NDF (fraction D) can be explained by the low lignin content and low complexity of lignin-cellulose bound in the soybean hulls [27], which favors the action of microflora present in the ruminants' digestive systems [22]. According to [28], the variation in the degradation rate of fraction d is due to the preference of rumen bacteria for different types of plant tissues. ...
This manuscript addresses the use of nutritional alternatives: that the addition of soybean hull levels affect protein and carbohydrate fractionation, with significant changes in rumen degradability; that most of the analyzed variables were affected linearly, so levels of additive inclusion resulted in the satisfactory growth of rumen microorganisms and synchronism between the protein and carbohydrate digestion rates; and that these had an important effect on the end products of fermentation and on animal production. This is significant because animals fed diets showing these characteristics can better express their animal performance. The results obtained in this study indicate that the addition of intermediate levels of soybean hulls close to 20-30% ensures better characteristics in the silage of Brachiaria decumbens. Abstract: This study aimed to determine the protein and carbohydrate fractions as well as the in situ rumen degradability of Brachiaria decumbens silage (BDS) supplemented with soybean hulls. Five soybean hull inclusion levels were used: 0, 10, 20, 30, and 40% of the fresh matter of B. decumbens grass, distributed into a completely randomized design with five replications. The inclusion of soybean hulls caused a linear decrease (p < 0.001) in carbohydrate fractions A + B1 and a linear increase (p < 0.001) in carbohydrate fraction C. The percentage of non-protein nitrogen fraction increased linearly (p < 0.001), but the nitrogen fractions B 1 + B 2 and B 3 presented a negative quadratic effect (p < 0.01) with soybean hull level and fraction C presented a linear decrease (p < 0.001). The dry matter (DM) degradability of soluble fraction (A) and the undigestible DM decreased linearly (p < 0.01) with the soybean hull level. The potentially degradable water-insoluble portion (DM fraction B) and degradability rate (c) of the DM fraction B increased linearly (p < 0.001) with soybean hull level. The crude protein (CP) fraction A presented a linear increase (p < 0.001) with soybean hull inclusion; however, soybean hull levels caused a linear decrease (p < 0.001) in the CP level of fraction B. The degradable insoluble fraction of NDF (D) of the silage increased linearly (p < 0.001) and the indigestible NDF fraction of the silage was linearly decreased with the soybean hull level (p < 0.001). The inclusion of intermediate levels (20-30%) of soybean hulls provided better protein and carbohydrate fractions and better quality of BDS.
... In addition, cotton residue treated with imidazole confirmed that temperature is an important factor influencing the cellulose content [26]. Likewise, the cellulose content increased with the severity of the reaction that was also shown by other pretreatment methods, such as sequential hydrothermal-imidazole pretreatment of elephant grass [16], ionic liquid ([bmin][Ac]) pretreatment of SH [27], and alkaline pretreatment of SH [28]. Therefore, to be a viable process within the context of lignocellulosic material reuse, it is important that the biomass choice and treatment type are allied to lower time and energy used in the process, such as was observed for SH imidazole pretreatment. ...
Soybean hulls (SH) are the main industrial waste from soybean processing, representing 5–8% of the whole grain. Imidazole was employed for the hydrothermal pretreatment of SH and further bioethanol production. Different pretreatment temperatures (120 and 180 °C) and times (1 and 3 h) were tested. Lignin removal and glucose yield were significantly influenced by temperature. After 48 h of enzymatic hydrolysis of imidazole-treated SH (120 °C, 1 h), 32.7 g/L of glucose and 9.4 g/L of xylose were obtained. A maximum bioethanol yield of 78.9% was reached after 12 h of fermentation by Saccharomyces cerevisiae using SH enzymatic hydrolysate. Imidazole appears to be a potential alternative to pretreat lignocellulosic wastes such as SH for the production of second-generation biofuels and other biomolecules.
... Biomass swelling of biomass and surface alteration after the alkaline pretreatment (data not shown) was observed, which was also previously reported by Camiscia et al. [39]. The swelling of lignocellulosic biomass represents the degradation of the ester and glycosidic chain and suggests an increase in the internal surface area, and solvation effect on the structural composition of the material [40,41]. ...
Alkaline pretreatment and sequential enzymatic hydrolysis of soybean hull were investigated to obtain fermentable sugars for polyhydroxyalkanoates production along with residual glycerol as low-cost carbon sources. Soybean hull is composed of approximately 32% cellulose, 12% hemicellulose, 6% lignin, and 11% protein. Alkaline pretreatment was carried out with 2% NaOH concentration, 10% (w/v) biomass loading, and 60 min incubation time in an autoclave at 120 °C. The response surface methodology (RSM) based on the central composite design (CCD) tool was employed to optimize the enzymatic hydrolysis process, where the variables of biomass loading, enzymes’ concentration, and time were considered. The maximum total reducing sugars concentration obtained was 115.9 g∙L−1 with an enzyme concentration of 11.5 mg protein/g dry substrate for enzyme preparation B1, 2.88 mg protein/g dry substrate for XylA, and 57.6 U/g dry substrate for β-glucosidase, after 42 h at 45 °C, and pH was 4.5. Subsequently, the saccharification step was conducted by increasing the processing scale, using a 1 L tank with stirring with a controlled temperature. Implementing the same enzyme concentrations at pH 4.5, temperature of 45 °C, 260 mL working volume, and incubation time of 42 h, under fed-batch operation with substrate feeding after 14 h and 22 h, a hydrolysate with a concentration of 185.7 g∙L−1 was obtained. Initially, to verify the influence of different carbon sources on Cupriavidus necator DSMz 545 in biomass production, batch fermentations were developed, testing laboratory-grade glucose, soybean hull hydrolysate, and waste glycerol (a by-product of biodiesel processing available in large quantities) as carbon sources in one-factor-at-a-time assays, and the mixture of soybean hull hydrolysate and waste glycerol. Then, the hydrolysate and waste glycerol were consumed by C. necator, producing 12.1 g∙L−1 of biomass and achieving 39% of polyhydroxyalkanoate (PHB) accumulation. To the best of our knowledge, this is the first time that soybean hull hydrolysate has been used as a carbon source to produce polyhydroxyalkanoates, and the results suggest that this agro-industrial by-product is a viable alternative feedstock to produce value-added components.
... Moreover, biotechnological valorization of SBH have considered the potential for carbohydrate hydrolysis, producing soluble sugars fermentable into biofuels and biochemicals [10,12,20]. Previous studies demonstrated that SBH are naturally more digestible than other lignocellulosic feedstocks such as corn stover and wheat straw [10,21,22]. Notably, one study indicated SBH can be converted at high yields in a simultaneous saccharification and fermentation process, without the need for a thermochemical pretreatment step prior to biochemical conversion [21]. ...
Soybean hulls (SBH) are an important agroindustrial residue that is highly susceptible to cellulolytic enzymatic digestion. The multiscale structure of this biomass should be able to inform on the origins of its digestibility, but such relationships are currently unknown. This work employs multimodal techniques to learn SBH variability and multiscale structure. Tissue-scale images obtained by electron microscopy, X-ray microtomography, and Raman spectromicroscopy reveal tissue ruptures, lignin localized in the hilum region, and oriented, quite pure cellulose in palisade and hourglass cells of the extra-hilar region. Such specificities of SBH cellulose are reinforced by X-ray diffraction showing cellulose crystallites ~ 20% wider than in typical lignocellulosic biomass. SBH are also remarkably more porous than other lignocellulosic feedstocks in the critical pore size (> ~ 10 nm) for enzyme accessibility. Enzymatic hydrolysis confirmed the low recalcitrance of SBH, demonstrating high yields (e.g., 80% glucose) without SBH pretreatment. These results provide a basis for rationalizing the low recalcitrance of SBH, paving the way for novel developments in SBH biotechnological valorization.
Graphical Abstract
... As an example, dilute acid hydrolysis of SBH fibers makes them a possible reinforcement material for the fabrication of natural fiber polymer complexes using 3D printing [99]. When alkaline pretreatment or bleaching process (with H 2 O 2 ) is applied, it is possible to recover the cellulose from SBH to be subsequently used as a potential adsorption matrix for the bio-separation of industrial enzymes [100], or for the synthesis of carboxymethyl cellulose after acetylation of bleached pulp [101]. Furthermore, SBH has been treated by partial oxypropylation technology to obtain, on the one hand, polyols for producing polyurethane foams and, on the other hand, superficially oxypropylated residue to prepare biphasic monocomponent composites [102]. ...
Soybean is one of the most abundant and cheap sources of high-quality vegetable protein. The most important suppliers of this commodity, as predicted for 2020/2021, are Brazil, the United States and Argentina, with 131, 112 and 53 million tons, respectively. China is expected to remain the greatest consumer (112 million tons). The main products obtained from soybean are the oil, the defatted bran, lecithin and in some cases the protein-concentrate bran. Soybean hulls and soybean molasses are the main residues to be valorized in a soybean biorefinery. This chapter will present the industrial processing of soybean, the variety of soy-derived products and the possible valorization strategies for soybean hulls and molasses. Socio-economic and environmental aspects within the soybean production chain will be addressed in a circular bioeconomy approach.
... Cellulose can be found in almost all plants as this compound provides structure to a plant's cell wall and also the source of dietary fibre [24,25]. Cellulose can be found in agricultural waste such as jackfruit rind [17][18][19]23], sugarcane bagasse [8,9,26], soybean [27] rice husk [6,7,28] and waste paper [1,4,20,29 ]. Almost 27.75% cellulose has been found in jack fruit rind [17,19]. ...
In this research, the cellulose has been successfully extracted from different type of wastes such as paper waste (empty tissue roll (ETR) & egg tray (ET) and fruit waste (jack fruit rind (JR)). From the extracted cellulose, the cellulose had been modified to Cellulose Acetate (CA). Modification of cellulose to CA involved acetylation process that used sulphuric acid (H2SO4) as catalyst. FTIR results showed that some of the peak disappeared after extraction process at certain wavelength (1700 – 1600 cm⁻¹, ∼1500 cm⁻¹). The intensity of few peaks at 3500 – 3000 cm⁻¹ and 3000 – 2800 cm⁻¹ also decreased after extraction process. All samples (ETR, ET and JR) for CA24 exhibit lowest intensity compared to other contact time. This might be due to the increasing of acetyl group in cellulose backbone and hydrophobicity of the film. This is due to the removal of certain compounds such as lignin and hemicellulose in all raw sample. The effect of contact time (1 to 24 hours) to the acetyl content and degree of substitution (DS) had been studied. It found that, for all wastes exhibited high acetyl content and high of degree of substitution when the contact was 24 hours. In mechanical properties, all CA24 film exhibit slightly higher tensile strain compare to cellulose film for both samples (ET, ETR and JR). Young's Modulus and tensile stress for CA24 film is also higher compare to cellulose film. This is due to the elimination of OH- groups which reduce the water sensitivity of cellulose and due to the internal plasticization of CH3CO- groups. Moreover, acetylation process increase the mechanical properties of the film produced. It can also be seen that Young's modulus increase with increase in CA contact time. This is expected, as addition of CA give a dense structure to film resulting in higher modulus values than porous structure. CA-24 film has the lowest moisture uptake. This is because CA-24 has lower OH- group presence in it. Therefore, ca-24 film shows better hydrophobicity. CA-24 film has lowest solubility most likely due to the replacement of OH- groups to CH3CO- groups. The replacement of OH- groups in cellulose with CH3CO- groups reduced its solubility in water but enhance its solubility in organic solvents. DSC results revealed that the CA24 for all samples (ETRP, ETR and JR) exhibit low Tg. This is due to the fact that, the increasing of contact of time, will increase the number of acetyl group. Hence, when the number of acetyl group increased, the hydrophobicity of the film also increased. Therefore, the ability of CA to form hydrogen bonding with water molecules also decrease. Hence, the segmental molecular ability increase due to the decreasing of hydrogen bonding in CA film.
... The increase in the degradation of the NDF (fraction D) can be explained by the low lignin content and low complexity of lignin-cellulose bound in the soybean hulls [27], which favors the action of microflora present in the ruminants' digestive systems [22]. According to [28], the variation in the degradation rate of fraction d is due to the preference of rumen bacteria for different types of plant tissues. ...
This study aimed to determine the protein and carbohydrate fractions as well as the in situ rumen degradability of Brachiaria decumbens silage (BDS) supplemented with soybean hulls. Five soybean hull inclusion levels were used: 0, 10, 20, 30, and 40% of the fresh matter of B. decumbens grass, distributed into a completely randomized design with five replications. The inclusion of soybean hulls caused a linear decrease (p < 0.001) in carbohydrate fractions A + B1 and a linear increase (p < 0.001) in carbohydrate fraction C. The percentage of non-protein nitrogen fraction increased linearly (p < 0.001), but the nitrogen fractions B1 + B2 and B3 presented a negative quadratic effect (p < 0.01) with soybean hull level and fraction C presented a linear decrease (p < 0.001). The dry matter (DM) degradability of soluble fraction (A) and the undigestible DM decreased linearly (p < 0.01) with the soybean hull level. The potentially degradable water-insoluble portion (DM fraction B) and degradability rate (c) of the DM fraction B increased linearly (p < 0.001) with soybean hull level. The crude protein (CP) fraction A presented a linear increase (p < 0.001) with soybean hull inclusion; however, soybean hull levels caused a linear decrease (p < 0.001) in the CP level of fraction B. The degradable insoluble fraction of NDF (D) of the silage increased linearly (p < 0.001) and the indigestible NDF fraction of the silage was linearly decreased with the soybean hull level (p < 0.001). The inclusion of intermediate levels (20–30%) of soybean hulls provided better protein and carbohydrate fractions and better quality of BDS.
... The insoluble carbohydrate fraction of cell walls of soybean hulls consists of 30% pectin, 50% hemicellulose, and 20% cellulose [13] and a small proportion of lignin. Camiscia et al. [14] compared soybean hulls with sugarcane bagasse, wheat straw and rice hulls and showed they have higher levels of lignocelluloses. Gnanasambandam and Proctor [15] reported that pectin from soybean hulls is a natural, inexpensive food grade form. ...
... CNPs were lower than these for PC, implying the decline of of thermal stability for the particles. It was probably due to the special characteristics of CNPs such as the lower molecular weight, higher surface area [22], and introduction of quaternary ammonium groups on cellulose chains [5,50]. The higher mass fraction of ash yielded from CNPs (18-41%) was indicated that the incorporation of quaternary ammonium functionalities might have a flame-retardant effect. ...
In this study, parenchyma cellulose, which was extracted from maize stalk pith as an abundant source of agricultural residues, was applied for preparing cellulose nanoparticles (CNPs) via an ultrasound-assisted etherification and a subsequent sonication process. The ultrasonic-assisted treatment greatly improved the modification of the pith cellulose with glycidyltrimethylammonium chloride, leading to a partial increase in the dissolubility of the as-obtained product and thus disintegration of sheet-like cellulose into nanoparticles. While the formation of CNPs by ultrasonication was largely dependent on the cellulose consistency in the cationic-modified system. Under the condition of 25% cellulose consistency, the longer sono-treated duration yielded a more stable and dispersible suspension of CNP due to its higher zeta potential. Degree of substitution and FT-IR analyses indicated that quaternary ammonium salts were grafted onto hydroxyl groups of cellulose chain. SEM and TEM images exhibited the CNP to have spherical morphology with an average dimeter from 15 to 55 nm. XRD investigation revealed that CNPs consisted mainly of a crystalline cellulose Ι structure, and they had a lower crystallinity than the starting cellulose. Moreover, thermogravimetric results illustrated the thermal resistance of the CNPs was lower than the pith cellulose. The optimal CNP with highly cationic charges, good stability and acceptable thermostability might be considered as one of the alternatively renewable reinforcement additives for nanocomposite production.
... Among the most important derivatizing techniques are etherification and esterification, particularly because they can result in high value-added products. Due to its broad range of applications and easy processability, the modification of cellulosic biomass into cellulose acetate (CA) has been the most commonly explored approach, and current research focuses mainly on the development of more sustainable processing methods (Daud and Djuned 2015;Camiscia et al. 2018). Recently, a fully bio-based and transparent ACC film was fabricated by the simple aqueous blending of water-soluble CA synthesized from waste cotton fabrics (WCFs) and nanocelluloses (Cao et al. 2016a). ...
... All of these peaks indicated the molecular group of the oligosaccharide. For the spectrum of XOS in xylanase pre-hydrolysate (Fig. 4b), the peak at 3300 cm −1 and 1619 cm −1 were assigned to the stretching vibration of −OH and COO-in the glucose (Camiscia et al., 2018;Robles-García et al., 2018), respectively. Besides, the peak at 1046 cm −1 was the characteristic peak (the stretching vibration of C-O-C on the XOS) of XOS, which indicated the existence of the glucose as well. ...
Current utilization of reed scraps (RS) from reed pulping mills is just burning and burying, remaining the unused RS a major industry waste. The aim of this study was to valorize RS by utilizing it as feedstock for xylo-oligosaccharide (XOS) production. The RS was subjected to dilute acid, alkaline, and liquid hot water (LHW) pretreatments to get the pretreated RS, which was then subjected to xylanase and subsequently cellulase enzymatic to produce XOS and glucose as well. The highest yield of XOS and glucose were 0.144 g and 0.304 g / g of RS, respectively, which were obtained from the LHW pretreatment under the optimized conditions of 170 °C, 1:8 solid loadings and 30 min duration. Overall, by upgrading RS waste into XOS and glucose as value-added products of reed pulp production, we thereby paved a new way in this research to valorize the waste from reed pulping mills.
In this work, a series of deep eutectic solvents (DES) were prepared using varying proportions of choline chloride and lactic acid. The DES were then employed to selectively extract lignin from bagasse fibers, resulting in bagasse fibers with varying lignin contents. By manipulating the lactic acid composition, bagasse fibers with lignin content ranging from 3.79 to 11.73 wt% of the total weight of the original bagasse were successfully produced, retaining most of the cellulose. Furthermore, the dissolution mechanism of the DES was experimentally characterized. These findings indicate that an increase in the lactic acid level leads to a finer particle size and dissolved cellulose shape. Furthermore, the mechanism by which lactic acid content influences the extraction of lignin units was investigated along with the morphological and elemental changes of cellulose within bagasse fibers after extraction. Additionally, the changes in structural composition, molecular weight, and β-d-xylopyranoside content of lignin were analyzed. This study offers novel perspectives on the environmentally friendly processing of cellulosic material with various lignin contents.
Textile industries represents one of the most pollutants industries due to the discharge of contaminated water into waterways. Around 20% of industrial water pollution arise from textile manufacture. Among the current remediation techniques, adsorption using agro-industrial wastes is emerging as an efficient tool. In this work, chemical semi-crystalline cellulose and its derivative functionalized with quaternary ammonium groups were assayed as adsorption beds. These adsorbents were physically characterized by Fourier transform infrared spectroscopy, X-ray diffraction, nitrogen adsorption to determine total surface area and differential scanning calorimetry. Applicability and efficiency of these biosorbers were assayed using Congo Red as a model textile dye which is an organic pollutant compound. Adsorption of this dye induced disorder onto the surface of cellulose modifying its morphology. The adsorption kinetics were studied, showing that the adsorption of the dye followed a pseudo-second order rate expression on both adsorbents. Different adsorption isotherm models were applied to describe the equilibrium isotherms. The empirical Freundlich model was found to be more suitable for both adsorbents. Adsorption capacities of the extracted and the cationized cellulose were 112 and 314 mg/g, respectively, therefore maximum adsorption capacity values (∼55 mg/g) were found to be much higher and adsorption times (20 – 90 min) were found to be much lower than the average of various Congo Red adsorbents produced from agro-industrial waste. A thermodynamic study showed that the adsorption of Congo Red onto cellulose and its cationic derivative was endothermic in nature (20.03 and 8.58 kJ/mol, respectively) with a positive entropic change.
Nanocellulose was isolated from okara using either ultrasound or high-pressure homogenization treatments. Dynamic light scattering, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, swelling behavior, rheological properties, and thermal analysis were used to characterize the physical-chemical and structural properties of the cellulose obtained. Sonication at 600 W for 15 min led to a cellulose material with a small mean particle diameter (d =0.22 μm), narrow polydispersity index (PDI = 0.21), strong negative charge (ζ = −36 mV), high swelling ratio (SR = 7.6), high crystallinity index (CI = 72 %), and formed viscous solutions. The initial pyrolysis temperature of the cellulose increased from 212 to 225 ℃, while the pyrolysis residue decreased from 26 to 12 %, after the sonication/homogenization treatment. The cellulose material produced in this study may be applied in various food and non-food applications as a texture modifier, stabilizer, structural component, or digestion modifier.
In this work, the extraction and purification of proteins present in soybean hull has been carried out, using simple methods and with the potential to be scaled. In the first stage, using statistical tools, the optimization of peroxidase extraction and various protease inhibitor factors was achieved through a leaching process using 50 mM phosphate buffer pH 6.00. The optimal conditions to achieve the best extraction of the proteins of interest were the following: contact time (360 minutes), mass / volume ratio (0.066) and particle size (40 mesh). The extract obtained was characterized by an electrophoresis gel, mass spectrometry and by measuring enzymatic activity, which, allowed to confirm the presence of the proteins of interest. Finally, the purification of peroxidase and protease inhibitors were optimized by adsorption onto aminated cellulose bed obtained from the same soybean hull. Under the optimal conditions, the peroxidase present in the extract was purified 8.1 times with a yield of 66.6%. While protease inhibitors were purified 2.5 times with a yield of 26.1%.
Supramolecular self-assembly, based on non-covalent interactions, has been used as an effective method to obtain various functional materials. In this work, a water soluble atomically precise Ag NCs(NH4)9[Ag9(C7H4SO2)9] (Ag9-NCs, [Ag9(mba)9], H2mba = 4-mercaptobenzoic acid) and cellulose nanocrystals (CNCs) were used to prepare supramolecular hydrogels by self-assembly, and these hydrogels have been characterized by using various techniques. The results revealed that the strong hydrogen bonds between the Ag9-NCs and CNCs were formed, and the strong interaction enhanced the mechanical properties, heat stability and self-healing ability of the nanocomposites. Moreover, the prepared Ag9-NCs/CNCs cryogels have shown excellent characteristics of low density and high compressive stress and it was found that the Ag9-NCs/CNCs films doped with Ag9-NCs still maintained the chiral nematic structure of the cellulose matrix. By preparing multiple forms of excellent Ag9-NCs/CNCs composite materials, it can be expected that they can be used in various application fields, such as the fields of biomedicine, support materials, and optoelectronics.
The need for biodegradable films for packaging, absorbents, and fibers has encouraged the development of novel biodegradable films made from natural sources, especially agricultural byproducts. The present investigation involved preparation of alpha cellulose and regenerated cellulose film, in view of the use of sugarcane bagasse, the cellulose-rich waste from the sugar industry. In order to prepare a cellulose pulp, the bagasse was exploded separately by saturated steam at temperatures of 195 °C and 205 °C for 5 min, washed, oven-dried, and submitted to an alkali pulping and bleaching process. The chemical compositions consisted of alpha cellulose, holocellulose, lignin, and the extractives of the bagasse and its pulp were analyzed. The results showed that the pulp contained high levels of alpha cellulose and low lignin. The cellulose pulp was being successfully regenerated as cellulosic films in an acid coagulation bath at different coagulation times. The characteristics of the steam exploded bagasse, cellulose pulp, and regenerated cellulose were investigated by SEM, XRD, FITR, TGA, tensile test, contact angle, and water retention measurement. The results of the XRD, FTIR and TGA all indicated that high alpha cellulose with low lignin pulp could successfully be made from steam-exploded sugarcane bagasse. The SEM images, contact angles, and water retention values also revealed that the regenerated films coagulated in an acid bath for 15 min were more hydrophilic than those that had coagulated for 30 min. The tensile test indicated that the regenerated cellulose films coagulated for 30 min were stronger than those coagulated for 15 min.
This work provides a critical overview of the recent trends toward the development of modern, dissolving pulp production technologies that respond to the current challenges and opportunities for the emerging low-carbon bioresource economy. Special attention is paid to recent advancements in prehydrolysis kraft pulping and conversion of paper grade pulp to dissolving pulp, with emphasis on the valorization of hemicellulose to value-added products. A comprehensive analysis of the current and future developmental opportunities for novel bioprocessing technologies and new products from dissolving pulp that aim to improve the process economics and enhance the industry competitiveness is presented and discussed.
This study used commercial enzymes to isolate cellulose nanofibrils (CN) and produce sugars from chemically pretreated soybean straw (SS) (stem, leaves, and pods) by alkali (NaOH 5 or 17.5% v/v at 90 oC for 1h, or at 30 oC for 15 h) and bleaching (NaClO2 3.3% or H2O2 4%) pretreatments. Depending on the pretreatment the soybean straw underwent, the yield of CN varied from 6.3 to 7.5 g of CN/100 g of SS regardless of the concentration of the alkaline solution (5 or 17.5%). The CN had diameter of 15 nm, measured over 300 nm in length, and had high electrical stability (zeta potentials ranged from -20.8 to -24.5). Given the XRD patterns, the crystallinity index (CrI) of CN ranged from 45 to 68%, depending on the chemical pretreatment the starting material was submitted to. CN obtained from SS treated with NaOH 17.5% and H2O2 (CrI = 45%) displayed better thermal stability probably because a lignin-cellulose complex emerged. The soluble fraction obtained in the first step of CN production contained a large amount of reducing sugars (11.2 to 30.4 g/100 g of SS). SS seems to be a new promising industrial source to produce CN via enzymatic-mechanical treatment, leading to large amounts of reducing sugars for use in bioenergy production.
α-Cellulose and microcrystalline cellulose powders, derived from agricultural waste products, that have for the pharmaceutical industry, desirable physical (flow) properties were investigated. α-Cellulose (GCN) was extracted from groundnut shell (an agricultural waste product) using a non-dissolving method based on inorganic reagents. Modification of this α -cellulose was carried out by partially hydrolysing it with 2N hydrochloric acid under reflux to obtain microcrystalline cellulose (MCGN). The physical, spectroscopic and thermal properties of the derived α-cellulose and microcrystalline cellulose powders were compared with Avicel® PH 101, a commercial brand of microcrystalline cellulose (MCCA), using standard methods. X-ray diffraction and infrared spectroscopy analysis showed that the α-cellulose had lower crystallinity. This suggested that treatment with 2N hydrochloric acid led to an increase in the crystallinity index. Thermogravimetric analysis showed quite similar thermal behavior for all cellulose samples, although the α- cellulose had a somewhat lower stability. A comparison of the physical properties between the microcrystalline celluloses and the α-cellulose suggests that microcrystalline cellulose (MCGN and MCCA) might have better flow properties. In almost all cases, MCGN and MCCA had similar characteristics. Since groundnut shells are agricultural waste products, its utilization as a source of microcrystalline cellulose might be a good low-cost alternative to the more expensive commercial brand.
Microcrystalline cellulose (MCC) was functionalized with quaternary amine groups for use as an adsorbent to remove Congo Red dye (CR) from aqueous solution. The ultrasonic pretreatment of MCC was investigated during its functionalization. Characterization was conducted using infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The batch adsorption of the functionalized MCC was studied to evaluate the effects of dye concentration, pH of solution, temperature, and NaCl concentration on the adsorption CR. The adsorbent (FM-1) obtained using ultrasonic pretreatment of MCC under 10.8 kJ·g-1 exhibited an adsorption capacity of 304 mg·g-1 at initial pH under a dose of 0.1 g·L-1 and initial concentration of 80 mg·L-1. After functionalization, the FT-IR and XPS results indicated that the quaternary amine group was successfully grafted onto the cellulose, the surface was transformed to be coarse and porous, and the crystalline structure of the original cellulose was disrupted. FM-1 has been shown to be a promising and efficient adsorbent for the removal of CR from an aqueous solution.
Non-cereal dietary fiber sources are compared and evaluated for cation exchange, water holding capacity and in vitro fermentabi1ity by gut microflora. Fiber sources studied include Psyllium gum, alfalfa, purified wood cellulose, pectin, cabbage, synthetic Maillard product, soybean hulls and propol. Sources are compared to the standard AACC wheat bran. Fermentability of the substrates alfalfa, wood cellulose and wheat bran show the largest unfermentable residue and the greatest differences between inocula sources (rumen inocula greater than human fecal inocula in all cases). Water-soluble sources (pectins) are completely fermentable, the exception of Psyllium gum which contains about 44% of an unfermentable residue. Cabbage pectin is unusual in having considerable cold water (50%) solubility. Cation exchange binding measured with copper are the highest for pectin, cabbage, bran, Maillard product = alfalfa and soybean hulls descending in that order. Wood cellulose, propol and Psyllium gum have essentially no metal binding capacity. Dietary fibers of high prophylactic value appear to have substantial metal binding capacity and are divisible into two classes based on fermentability. Human feeding studies indicate that the fiber sources containing unfermentable residues will contribute to fecal bulk and, therefore, transit and passage, while the more fermentable have their major effects upon gut microflora. These two aspects are complementary relative to the effectiveness of dietary fiber. The identification of dietary fibers as an overlooked factor in human health and disease has promoted a great deal of interest 0097-6156/83/0214-0135$06.00/0 © 1983 American Chemical Society Downloaded by
Cellulose is among the most important and abundant biopolymers in biosphere. It is the main structural component of a vast number of plants that carries vital functions for plant growth. Cellulose-based materials have been used in a variety of human activities ranging from papers and fabrics to engineering applications including production of biofuels. However, our understanding of the cellulose structure in its native form is quite limited because the current experimental methods often require separation or purification processes and provide only partial information of the cellulose structure. This paper aims at providing a brief background of the cellulose structure and reviewing the basic principles, capabilities and limitations of the cellulose characterization methods that are widely used by engineers dealing with biomass. The analytical techniques covered in this paper include x-ray diffraction, nuclear magnetic resonance, and vibrational spectroscopy (infrared, Raman, and sum-frequency-generation). The scope of the paper is restricted to the application of these techniques to the structural analysis of cellulose.
The bulk terrestrial biomass resource in a future bio-economy will be lignocellulosic biomass, which is recalcitrant and challenging to process. Enzymatic conversion of polysaccharides in the lignocellulosic biomass will be a key technology in future biorefineries and this technology is currently the subject of intensive research. We describe recent developments in enzyme technology for conversion of cellulose, the most abundant, homogeneous and recalcitrant polysaccharide in lignocellulosic biomass. In particular, we focus on a recently discovered new type of enzymes currently classified as CBM33 and GH61 that catalyze oxidative cleavage of polysaccharides. These enzymes promote the efficiency of classical hydrolytic enzymes (cellulases) by acting on the surfaces of the insoluble substrate, where they introduce chain breaks in the polysaccharide chains, without the need of first "extracting" these chains from their crystalline matrix.
Two new methods based on FT–Raman spectroscopy, one simple, based on band intensity ratio, and the other using a partial least
squares (PLS) regression model, are proposed to determine cellulose I crystallinity. In the simple method, crystallinity in
cellulose I samples was determined based on univariate regression that was first developed using the Raman band intensity
ratio of the 380 and 1,096cm−1 bands. For calibration purposes, 80.5% crystalline and 120-min milled (0% crystalline) Whatman CC31 and six cellulose mixtures
produced with crystallinities in the range 10.9–64% were used. When intensity ratios were plotted against crystallinities
of the calibration set samples, the plot showed a linear correlation (coefficient of determination R
2=0.992). Average standard error calculated from replicate Raman acquisitions indicated that the cellulose Raman crystallinity
model was reliable. Crystallinities of the cellulose mixtures samples were also calculated from X-ray diffractograms using
the amorphous contribution subtraction (Segal) method and it was found that the Raman model was better. Additionally, using
both Raman and X-ray techniques, sample crystallinities were determined from partially crystalline cellulose samples that
were generated by grinding Whatman CC31 in a vibratory mill. The two techniques showed significant differences. In the second
approach, successful Raman PLS regression models for crystallinity, covering the 0–80.5% range, were generated from the ten
calibration set Raman spectra. Both univariate-Raman and WAXS determined crystallinities were used as references. The calibration
models had strong relationships between determined and predicted crystallinity values (R
2=0.998 and 0.984, for univariate-Raman and WAXS referenced models, respectively). Compared to WAXS, univariate-Raman referenced
model was found to be better (root mean square error of calibration (RMSEC) and root mean square error of prediction (RMSEP)
values of 6.1 and 7.9% vs. 1.8 and 3.3%, respectively). It was concluded that either of the two Raman methods could be used
for cellulose I crystallinity determination in cellulose samples.
KeywordsCellulose-Crystallinity-Raman spectroscopy-FT–Raman-Univariate-Multivariate-PLS-X-ray
Potentiometric mass titration (PMT) technique has been adapted to determine the pH
pzc of four vegetable wastes: grape stalks, cork, yohimbe bark and olive stones wastes used for Cu(II) removal. The pH at the
point zero charge (pH
pzc), determined by PMT, are compared with that obtained by two classical techniques: mass titration (MT) and immersion technique
(IT). PMT has been found to be an easy and appropriate technique to determine pH
pzc of the studied materials. From the results, the knowledge of sorbents pH
pzc provides information about the possible attraction and repulsion between sorbent and sorbate but in any case enables to ensure
that electrostatic force is one of the mechanisms that takes place in metal sorption.
Cellulose powder and cellulose pellets obtained by pressing the microcrystalline powder were studied using differential scanning
calorimetry (DSC), differential thermal analysis (DTA), and thermal gravimetry (TG). The TG method enabled the assessment
of water content in the investigated samples. The glass phase transition in cellulose was studied using the DSC method, both
in heating and cooling runs, in a wide temperature range from −100 to 180°C. It is shown that the DSC cooling runs are more
suitable for the glass phase transition visualisation than the heating runs. The discrepancy between glass phase transition
temperature T
g found using DSC and predictions by Kaelbe’s approach are observed for “dry” (7 and 5.3% water content) cellulose. This could
be explained by strong interactions between cellulose chains appearing when the water concentration decreases. The T
g measurements vs. moisture content may be used for cellulose crystallinity index determination.
Raman and Fourier Transform Infrared (FT-IR) spectroscopy was used for assessment of structural differences of celluloses of various origins. Investigated celluloses were: bacterial celluloses cultured in presence of pectin and/or xyloglucan, as well as commercial celluloses and cellulose extracted from apple parenchyma. FT-IR spectra were used to estimate of the I(β) content, whereas Raman spectra were used to evaluate the degree of crystallinity of the cellulose. The crystallinity index (X(C)(RAMAN)%) varied from -25% for apple cellulose to 53% for microcrystalline commercial cellulose. Considering bacterial cellulose, addition of xyloglucan has an impact on the percentage content of cellulose I(β). However, addition of only xyloglucan or only pectins to pure bacterial cellulose both resulted in a slight decrease of crystallinity. However, culturing bacterial cellulose in the presence of mixtures of xyloglucan and pectins results in an increase of crystallinity. The results confirmed that the higher degree of crystallinity, the broader the peak around 913 cm(-1). Among all bacterial celluloses the bacterial cellulose cultured in presence of xyloglucan and pectin (BCPX) has the most similar structure to those observed in natural primary cell walls.
The points of zero charge/potential of proteins depend not only on pH but also on how they are measured. They depend also on background salt solution type and concentration. The protein isoelectric point (IEP) is determined by electrokinetical measurements, whereas the isoionic point (IIP) is determined by potentiometric titrations. Here we use potentiometric titration and zeta potential (ζ) measurements at different NaCl concentrations to study systematically the effect of ionic strength on the IEP and IIP of bovine serum albumin (BSA) aqueous solutions. It is found that high ionic strengths produce a shift of both points toward lower (IEP) and higher (IIP) pH values. This result was already reported more than 60 years ago. At that time, the only available theory was the purely electrostatic Debye-Hückel theory. It was not able to predict the opposite trends of IIP and IEP with ionic strength increase. Here, we extend that theory to admit both electrostatic and nonelectrostatic (NES) dispersion interactions. The use of a modified Poisson-Boltzmann equation for a simple model system (a charge regulated spherical colloidal particle in NaCl salt solutions), that includes these ion specific interactions, allows us to explain the opposite trends observed for isoelectric point (zero zeta potential) and isoionic point (zero protein charge) of BSA. At higher concentrations, an excess of the anion (with stronger NES interactions than the cation) is adsorbed at the surface due to an attractive ionic NES potential. This makes the potential relatively more negative. Consequently, the IEP is pushed toward lower pH. But the charge regulation condition means that the surface charge becomes relatively more positive as the surface potential becomes more negative. Consequently, the IIP (measuring charge) shifts toward higher pH as concentration increases, in the opposite direction from the IEP (measuring potential).
The thermal degradation behavior and pyrolytic mechanism of cellulose, hemicellulose, and lignin are investigated at different heating rates from 10 Kmin⁻¹ to 100 Kmin⁻¹ with a step-size of 10 Kmin⁻¹ using thermogravimetric analysis (TGA) equipment. It is observed that there are one, two, and three stages of pyrolytic reactions takes place in cellulose, hemicellulose, and lignin respectively. Isoconversional method is not suitable to analyse pyrolysis of hemicellulose and lignin as it involves multi-step reactions. The activation energies of the main decomposition stage for cellulose, hemicellulose, and lignin are 199.66, 95.39, and 174.40 kJ mol⁻¹ respectively. It is deduced that the pyrolysis reaction of cellulose corresponds to random scission mechanism while the pyrolysis reaction of hemicellulose and lignin follows the order based reaction mechanisms.
Cellulose nanofibrils and lignin were simultaneously isolated from waste jute bags using soda cooking pretreatment method. Soda cooking resulted in reduction of recalcitrance of lignocellulose biomass leading to hydrolysis of hemicellulose into sugars, which was subsequently washed, leaving a residue of cellulose and lignin.The chemical composition, yield of lignin and cellulose were assessed using TAPPI method and ASTM standards, respectively. Yields of lignin and cellulose were 58 and 45%, respectively, calculated separately on the basis of their content in the jute bags. FTIR results confirmed the removal of lignin and hemicellulose from raw jute fibers during soda cooking process. (H)NMR results depicted the aromatic structure of lignin which was further confirmed by UV results which clearly indicated the presence of phenolic compounds. The thermal stability of cellulose nanofibrils and lignin was higher than raw jute fibers. SEM showed cylindrical cellulose nanofibrils and agglomerates of amorphous and crystalline region of lignin. Size of jute fibers decreased to 12-18nm whereas the crystallinity increased after chemical and mechanical treatments studied using TEM and XRD, respectively. The study confirmed the isolation of cellulose nanofibrils and lignin extraction discarding the hemicellulose using single pot treatment.
The thermal stability of cellulose nanofibrils (CNFs) can be improved by converting cellulose crystalline structure to cellulose II using an alkaline treatment method. The conventional method requires around 20 wt.% NaOH solutions and causes the cellulose interdigitation and aggregation, making CNFs production difficult. The objective of this study is to develop a new pretreatment method using a low-concentration alkaline solution to produce well-dispersed CNFs with improved thermal stability. CNFs with 90 nm diameter were successfully prepared by treating cellulose powder with 2 wt.% NaOH solution below 0 °C, followed by homogenization through a French pressure cell press. The CNFs had relatively high thermal stability with the mean onset and maximum thermal decomposition temperature of 305 °C and 343 °C, respectively, compared with the CNFs prepared without the NaOH pretreatment (283 °C and 310 °C). The increased thermal stability can create new opportunities for the development of CNF-based bio-composites and electronics.
In this work, using cotton pulps and urea as raw materials, cellulose carbamates (CCs) were successfully prepared by liquid-solid phase in the high-boiling aprotic and polar solvent (DMAc). Regenerated cellulose (RC) fibers were successfully spun from cellulose carbamate in a NaOH aqueous solution by wet spinning on a conventional viscose filament device. And the structures and properties of products were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), Thermal gravimetric analysis (TG) and Scanning electron microscopy (SEM), rheology measurement and dye testing. The results showed that the CC can be quickly dissolved in 9%NaOH solution. RC fibers exhibited a bright surface and an approximately circular cross section. There was no lobulate shape and contained obvious pores and voids in the internal sections. RC fibers demonstrated a typical cellulose II crystal structure and a good thermal stability. And tensile strength of the RC fibers was 1.4 cN/dtex, and their elongation at break was 6.8%. Furthermore, the RC fibers showed excellent dyeing properties compared with viscose rayon and Yingli Lyocell. So, the described carbamate pathway provided a simple and environmentally friendly method to overcome the environmental drawbacks of the traditional viscose process.
Cellulose nanocrystals (CNCs) were prepared from waste cotton cloth and degreasing cotton was used as a comparison. The cellulose was first extracted by alkali and bleaching treatments, and then the CNCs were isolated by the mix acid solution hydrolysis of cellulose under the controlled conditions. The CNCs were analyzed by Attenuated total reflectance Fourier transform infrared spectroscopy, Transmission electron microscopy, X-ray diffraction analysis, thermogravimetric and differential scanning calorimetry analysis. The results confirmed that the resultant samples were the cellulose species, and the CNCs obtained from waste cotton cloth exhibited a high crystallinity index of 55.76 ± 7.82%, which had higher thermostability than that from the degreasing cotton. The morphology analysis results showed that the ranges of length and diameter of CNC extracted from waste cotton cloth were from 28 to 470 nm and 3 to 35 nm. The preparation of CNCs with a high aspect ratio and good thermostability in this work paves the way for an alternative reuse of waste cotton cloth.
The pyrolysis characteristics of three main components (hemicellulose, cellulose and lignin) of biomass were investigated using a thermogravimetric analyzer (TGA) and a fixed-bed reactor, respectively. In TGA, the pyrolysis of hemicellulose and cellulose occurred quickly with a weight loss from 210 to 370°C for hemicellulose and from 260 to 410°C for cellulose. Lignin decomposed over a wider range of temperature (from 200 to about 600°C) and generated a high char yield. As the heating rate increased, TG and DTG curves shifted to the higher temperatures. The Flynn-Wall-Ozawa method was introduced to analyze the thermal reaction kinetics, and the activation energy (E) values of hemicellulose, cellulose and lignin pyrolysis are in correspondence with thermostability sequence of these three components. In the fixed-bed reactor, the pyrolysis of lignin generated remarkably high solid residue yield (61%) and very low liquid yield (0.5%) compared with cellulose and hemicellulose. The noncondensable gas mainly consisted of H2, CH4, CO2 and CO. FTIR and GC-MS analysis of liquids showed that liquids from cellulose and hemicellulose pyrolysis included a range of light oxygenated compounds which was indicated that furans, aldehydes and ketones were the most prominent decomposition products. The depolymerization of lignin led to various phenols, including many methoxylated phenols. After pyrolysis, the carbon content in char increased while the hydrogen content decreased. All of the results and findings would help further understanding of thermal behavior of biomass and its thermo-chemical utilization for fuels and chemicals.
This paper presents the technical-economic and environmental assessment of four lignin extraction processes from two different raw materials (sugarcane bagasse and rice husks). The processes are divided into two categories, the first processes evaluates lignin extraction with prior acid hydrolysis step, while in the second case the extraction processes are evaluated standalone for a total analysis of 16 scenarios. Profitability indicators as the net present value (NPV) and environmental indicators as the potential environmental impact (PEI) are used through a process engineering approach to understand and select the best lignin extraction process. The results show that both economically and environmentally process with sulfites and soda from rice husk presents the best results; however the quality of lignin obtained with sulfites is not suitable for high value-added products. Then, the soda is an interesting option for the extraction of lignin if high quality lignin is required for high value-added products at low costs.
Infrared absorption spectra of oriented cellulose fibers have been observed using polarized radiation. Natural fibers are in general too thick but swelling them in NaOH solution followed by pressing and drying is an effective way of obtaining a suitable thickness in the and regions. The dichroism observed for the bands which can be assigned agrees well with tha: predicted from the crystal structure1, e. g. the CH stretching bands are polarized perpendicular to the fiber axis. In the region of CH and OH deformation frequencies () nine bands are observed, of which four are polarized parallel and five, perpendicular to the fiber axis. Probable assignments will be given for these bands. In the region of CO and CC stretching frequencies () all the bands are polarized parallel to the fiber axis. Observations were also made on deuterated cellulose i.e. cellulose which had been swelled in NaOD. Of the six OD stretching bands observed, five show parallel dichroism, indicating that the OH bands in cellulose are arranged predominantly parallel to the fiber axis. The deuteration of amorphous cellulose will also be discussed.
Here we report the production of highly thermal stable and functional cellulose nanocrystals (CNC) and nanofibrils (CNF) by hydrolysis using concentrated organic acids. Due to their low water solubility, these solid organic acids can be easily recovered after hydrolysis reactions through crystallization at a lower or ambient temperature. When dicarboxylic acids were used, the resultant CNC surface contained carboxylic acid groups which facilitate functionalization and dispersion in aqueous processing. Carboxylic acid group content was 0.1 – 0.4 mmol/g for CNC produced from a bleached eucalyptus kraft pulp (BEP) using oxalic acid at concentrations of 50 – 70 wt%. Onset thermal degradation temperature for the CNC was increased to 322°C from 274°C for the feed BEP fibers, compared with 218°C for CNC produced from the same feed fibers using conventional concentrated sulfuric acid hydrolysis. The low strength (high pKa) of organic acids also resulted in CNC with longer lengths of approximately 275 – 380 nm and higher crystallinity than those produced using mineral acids. Fibrous cellulosic solid residue (FCSR) collected from acid hydrolysis was an excellent feedstock for producing CNF through subsequent mechanical fibrillation with low energy input. The ability to recover the organic acids using a conventional and commercially proven crystallization method makes these organic acids uniquely suited for sustainable and green production of cellulose nanomaterials. The resultant CNC and CNF with high thermal stability and large aspect ratio are excellent for bio-composite applications.
Soybean hulls were used to isolate cellulosic microfibrils (SMF) and brick-like microparticles (SMP) by combining chemical and mechanical pretreatments. The key physical and chemical features of SMF and SMP were compared with those of micro and nanofibrillated cellulose (MNFC) obtained from fully bleached wood fibers. SMF and SMP chemical composition includes residual polysaccharides and lignin that endow such biologically-derived materials with properties typical of nanocellulosics. Compared to MNFC, SMF and SMP exhibit enhanced crystallinity (∼ > 10% higher) and thermal stability (onset degradation temperature >295 °C and maximum degradation at 361 and 355 °C). Such observations make SMF and SMP suitable for reinforcement in thermoplastic composites. A strong shear thinning behavior was observed for aqueous dispersions of SMF and SMP, revealing that these cellulose microstructures are of interest for rheology modification, coatings and films. Overall, the availability and low cost of biomass from residual soybean hulls constitutes a viable option for their use as a feedstock for the production and development of novel materials from SMF and SMP.
The polysaccharides of soy hulls were extracted by hot-compressed water at temperatures of 110 from 180 °C and various treatment times (10-150 min) in a batch system. It was determined that a moderate temperature and short time are suitable for the preparation of polysaccharides. The structure of xylan and the inter- and intra-chain hydrogen bonding of cellulose fibrils in the soy hulls were not significantly broken down. The polysaccharides obtained were primarily composed of α-L-arabinofuranosyl units, 4-O-methyl-glucuronic acid units and α-D-galactose units attached with substituted units. A sugar analysis indicated that arabinose was the major component, constituting 35.6%-46.9% of the polysaccharide products extracted at 130 °C, 140 °C, and 150 °C. This investigation contributes to the knowledge of the polysaccharides of soy by-products, which can reduce the environmental impact of waste from the food industries.
Three spectrophotometric methods were evaluated in order to determine total phenolic compounds content in propolis from Tucumán, Argentina; applying the Folin-Ciocalteau, Prussian blue and ophenanthroline methods. The Prussian blue method was the most sensitive one although it was also unstable. The o-phenanthroline method may be more reliable and proved to be quite sensitive and stable. Folin-Ciocalteau method was the most stable and reproducible of all. The statistic analysis for such methods as well as for each of the controls used showed that all the three methods were different at 1% significance levels, except for the Prussian blue and o-phenanthroline methods, which yielded no significant differences for the quercetin control solution.
Starch was allowed to react thermochemically (oven versus drum drying-oven) with citric acid to potentially yield biodegradable products possessing high ion exchange capacity. Reaction variables studied were: starch type (amylose content 0-70%), pH (0.5-8.5), sodium level (0-3 moles), citric acid level (0.1-0.5 moles), reaction time, temperature (110-140°C) and sodium dihydrogen phosphate catalysis. Reaction efficiencies approaching 100% were achieved,while minimizing crosslinking and maximizing carboxyl content. Carboxyl content was determined and copper binding capacity at pH 4.5 was evaluated.
In this study, variations in the delignification and bleaching stages, acid hydrolysis and high-pressure homogenization, led to the development of 12 different treatments applied for obtaining nanofibers using fibrous residues arising from the starch extraction process from the achira rhizomes. The treatments were evaluated based on some properties and characteristics of nanofibers such as: morphology and size (by means of transmission electron microscopy), surface charge (by means of zeta potential measurements), crystallinity index (by means of X-ray diffraction analysis) and functional groups (by means of infrared spectroscopy). In general, the nanofibers showed particle diameters between 13.8 and 37.2nm, length between 832.8 and 2223.8nm and high crystallinity index (57.5% and 69.8%) compared with achira fibrous residue (17.3%). The results evidenced that fibrous residue from achira rhizomes can be used as a source of biodegradable materials of commercial interest.
Copyright © 2015 Elsevier Ltd. All rights reserved.
In the last few decades, the usages of plant sources-based stiff fillers as reinforcement material in polymer composites have attracted significant interests of researchers. The crystalline part of the semicrystalline cellulose chains as found in the plant cell walls represents the most highly potential reinforcing agents for polymer. This review systematically covers the extraction of nano-sized cellulose crystals from plant cell wall which involving the applications of several highly effective techniques. The topic about the derivation of products functionality at each stage as well as their influences on the final reinforcing capability is also covered. Apart from these, a detailed overview of current knowledge on the surface modification of nanocellulose has been provided also. Inasmuch, this paper is desired to encourage the emergence of preparation of cellulose derivative nanocrystals with controlled morphology, structure and properties, so that enable positive development of biocompatible, renewable and sustainable reinforcing materials for polymer composites field.
Modification of starch by cross-linking is used in many fields, as the process improves many of the properties of starch, yet most cross-linking agents in common use tend to be toxic, expensive, or both. Polycarboxylic acids could function as nontoxic alternatives to these – some, such as tartaric acid (TA) being also of low cost. This study presents a method to cross-link thermoplastic starch films with TA, as well as the effect of this modification on the tensile strength of the material when films are prepared using different reaction conditions. An increase in strength was observed, which is believed to occur due to an increase in the London dispersion forces acting within the cross-linked starch (CLS). The greatest observed increase in the maximum tensile strength of the plastic was 6%. Monosodium tartrate was used as a catalyst for the cross-linking reaction. The maximum tensile strengths of the plastics produced were determined by using adapted binder clips, a hook (total mass 10g) and hanging mass...
In this study, microcrystalline cellulose (Alfa-MCC) was extracted from Alfa fibres using acid hydrolysis method. The molecular weight of the cellulose samples was determined by gel permeation chromatography. The crystallinities were studied by means of X-ray diffraction and solid state cross polarization magic angle spinning 13C nuclear magnetic resonance spectroscopy, revealing that Alfa-MCC was more crystalline than the native cellulose isolated from Alfa fibres. The morphology of the celluloses was investigated using scanning electron microscopy, showing a compact structure and a rough surface. Furthermore, a good thermal stability was shown for Alfa-MCC. Based on these analyses, Alfa-MCC showed tremendous potential use as composites reinforcing agent, foods stabilizer and pharmaceutical additive.
Cationic polysaccharides are widely used in diverse areas such as water treatment, papermaking, chemical, food, cosmetic, petroleum industries, etc. The combination of cationic polysaccharides with anionic polymers can lead to interpolyelectrolyte complexes with hydrogel-like structures further expanding the application of the former.The aim of the present review is to fill a gap on the literature about cationization reactions of different polysaccharides and to offer a systematic and up-to-date analysis on the subject. Polysaccharides such as starch, dextran, cellulose and its derivatives, hemicellulose, pectin, chitosan, and seaweed polysaccharides among others are considered. Cationized polysaccharides can be prepared by reaction with various reagents. The main focus is on the substitution with dialkylamino hydroxypropyl and trialkylammonium hydroxypropyl ethers, being that the most common modifications involves the introduction of the 2-hydroxy-3-(trimethylammonium)propyl group by reaction of the polysaccharide with 2,3-epoxypropyltrimethylammonium chloride in an alkaline solution. An alternative to this method involves generation of the reagent in situ from 3-chloro-2-hydroxypropyltrimethylammonium chloride. In addition, polysaccharides substituted with other type of cationic groups and amphoteric derivatives are presented. Different methods of analysis, toxicological studies and applications of the modified polymers are also included.
In this study, thermogravimetric (TG) analyses, along with thermal and catalytic fast pyrolysis experiments of cellulose, hemicellulose, lignin and their mixtures were carried out in order to investigate their pyrolysis products and whether the prediction of the pyrolysis behavior of a certain lignocellulosic biomass feedstock is possible, when its content in these three constituents is known. We were able to accurately predict the final solid residue of mixed component samples in the TG analyses but the differential thermogravimetric (DTG) curves indicated limited heat transfer when more than one component was present in the pyrolyzed sample. The limited heat transfer did not have a significant effect on the TG curves but it affected the product distribution in the fast pyrolysis experiments, which resulted in inaccurate calculation of the product yields, when using a simple additive law. In addition, the pyrolysis products of each biomass constituent were characterized in order to study their contribution to the yield and composition of the products from whole biomass pyrolysis. An investigation into the pyrolysis reaction pathways of each component was also carried out, using the bio-oil characterization data from this study and data found in the literature.
Soy hulls are an agro-industrial residue available in huge quantities throughout the world whose application deserves more attention than simply as cattle feed. This work evaluates the use of soy hulls as a source of cellulose to obtain nanocrystals by acid hydrolysis. The hydrolysis was performed at 40 °C for 30 or 40 min, using 30 mL of H2SO4 64% for each gram of cellulose. The resulting nanocrystals were characterized by crystallinity index, morphology, surface charge and thermal stability. The results showed that the more drastic hydrolysis conditions (40 min) resulted in a shorter length of nanocrystals and caused some damage on the crystalline structure of the cellulose. At an extraction time of 30 min, the nanocrystals presented a high crystallinity (73.5%), an average length of 122.66 ± 39.40 nm, a diameter of 2.77 ± 0.67 nm and an aspect ratio around 44, therefore presenting a great potential as reinforcement in nanocomposite preparations.
Soybean hulls modified with citric acid have enhanced capabilities for adsorbing metals from wastewater and have the potential to compete in the marketplace as ion-exchange resins. The objective of this study was to determine the optimal conditions for citric acid modification of soybean hulls and to estimate the cost of the modification process. Adsorption capacities for copper ion (Cu2+) were determined on unwashed, water-washed and 0.1 N NaOH-washed soybean hulls. All three samples had the same adsorption capacities. Therefore, unwashed hulls were selected as the feedstock for citric acid modification. The citric acid-treated hulls required a drying step before modification could proceed. However, the drying and modification steps could be combined into a single process step when the wet hulls were heat-treated at 120°C for 1.5 h. A process flow diagram was developed based on these results. From the process description and equipment needed to manufacture the modified product, the capital and operating costs were determined. The product cost was estimated, based on a daily input of 10 000 kg of soybean hulls and a daily output of modified product of 7900 kg, with a yield of 79%. An estimated production cost for the modified product was 4–40/kg for commercial, petroleum-based cation-exchange resins when purchased in bulk quantities.
A method was developed to enhance metal ion adsorption of soybean hulls for wastewater treatment using copper ion (Cu2+) as a typical metal ion. Hulls, extracted with 0.1 N NaOH, were modified with different citric acid (CA) concentrations (0.1-1.2 M) at 120°C for 90 min. CA-modified hulls had adsorption capacities for Cu2+ from 0.68 to 2.44 mmoles/g, which was much higher than for unmodified hulls (0.39 mmoles/g). The total negative charge for these hulls also increased with increasing CA concentration and was about twice the copper ion adsorption capacity at all CA concentrations. The need for NaOH (base) extraction (BE) before CA modification was examined. CA-modified, non-extracted (NE) and CA-modified, BE hulls were compared for adsorption kinetics and adsorption capacity. Base extraction resulted in modified hulls with faster adsorption kinetics and slightly lower adsorption capacity for copper ion than NE hulls. For BE, CA-modified hulls, increasing the temperature from 25°C to 60°C appeared to have no effect on the rate of copper ion removal from solution. CA modification of soybean hulls greatly enhanced metal ion removal and resulted in a product with possible commercial potential for metal ion remediation.
Treatment of dewaxed maize stems, rye straw, and rice straw with 1 M NaOH at 30 °C for 18 h resulted in a dissolution of 78.0, 68.8, and 82.1% of the original lignin, and 72.1, 72.6, and 84.6% of the original hemicelluloses, respectively. The three alkali lignin fractions and three hemicellulosic preparations and the corresponding residues (mainly cellulose) were characterized by both degraded methods, such as alkaline nitrobenzene oxidation and acid hydrolysis, and non-destructive techniques, e.g. ultraviolet (UV), Fourier transform infrared (FT-IR), carbon-13 nuclear magnetic resonance spectroscopies (13C-NMR), and gas permeation chromatography (GPC). It was found that the three lignin preparations contained substantial amounts of non-condensed guaiacyl and syringyl units with fewer p-hydroxyphenyl units, and had weight-average molecular weights between 3280 and 3890 g mol−1. The two hemicellulosic preparations, obtained from maize stems and rye straw, were dominant in glucuronoarabinoxylans. While the hemicelluloses present in rice straw were mainly composed of α-glucan and k-arabino-(4-O-methyl-d-glucurono)-d-xylan. The thermal analysis of the polymers showed that hemicelluloses degraded in first place, while lignin showed less degradation, and therefore, its structure was more stable. Cellulose, on the other hand, showed an important degradation process, mainly between 250 and 330 °C, and its thermal stability is lower than that of lignin, but higher than that of hemicelluloses.
Deterioration of books and archive materials is due to degradation of cellulose that is caused by many factors such as acidic hydrolysis, oxidative agents, light, air pollution or presence of microorganisms. Recently, FT-IR and FT-Raman spectroscopy have been used for the characterization of cellulose and its degradation products. In this work, we present vibrational spectra obtained with different sampling techniques of pure cellulose from softwood and cotton that has been hydrothermally treated for maximum 21 days in extreme humid atmosphere (100% humidity, 100°C). We show that the obtained results strictly depend upon spectroscopic techniques used in measurements. We also present and discuss changes in vibrational spectra pointing out a role that is played by water molecules in this accelerated aging process of paper.
Applying special computer mathematical treatments to increase resolution of experimental spectra there were established a set of stable characteristic bands for isolated softwood lignins. In the 740–1620 cm−1 spectral range the band maximum positions did not change but values of bandwidths and peak intensities were varied in limits 15% and 32%. After analysis of the infrared spectra of 30 investigated samples a softwood lignin spectral model was constituted. This model allowed to clear discrepancies in the bands parameters of different mild isolated (lignins of Bjorkman, Pepper and Freudenberg), dioxane and technical lignin spectra. It was helpful for studying lignin structure changes during degradation procedures.
Physico-chemical pretreatment of lignocellulosic biomass is critical in removing substrate-specific barriers to cellulolytic enzyme attack. Alkaline pretreatment successfully delignifies biomass by disrupting the ester bonds cross-linking lignin and xylan, resulting in cellulose and hemicellulose enriched fractions. Here we report the use of dilute alkaline (NaOH) pretreatment followed by enzyme saccharifications of wheat straw to produce fermentable sugars. Specifically, we have assessed the impacts of varying pretreatment parameters (temperature, time and alkalinity) on enzymatic digestion of residual solid materials. Following pretreatment, recoverable solids and lignin contents were found to be inversely proportional to the severity of the pretreatment process. Elevating temperature and alkaline strengths maximised hemicellulose and lignin solubilisation and enhanced enzymatic saccharifications. Pretreating wheat straw with 2% NaOH for 30 min at 121 degrees C improved enzyme saccharification 6.3-fold When compared to control samples. Similarly, a 4.9-fold increase in total sugar yields from samples treated with 2% NaOH at 60 degrees C for 90min, confirmed the importance of alkali inclusion. A combination of three commercial enzyme preparations (cellulase, beta-glucosidase and xylanase) was found to maximise monomeric sugar release, particularly for substrates with higher xylan contents. In essence, the combined enzyme activities increased total sugar release 1.65-fold and effectively reduced cellulase enzyme loadings 3-fold. Prehydrolysate liquors contained 4-fold more total phenolics compared to enzyme saccharification mixtures. Harsher pretreatment conditions provide saccharified hydrolysates with reduced phenolic content and greater fermentation potential. (C) 2011 Elsevier Ltd. All rights reserved.
This chapter summarizes the most widely used methods for determining lignin. Researchers should always include known lignin samples or samples of known lignin content as controls in any procedure. The chapter describes procedures that are developed for plant tissues but should be adaptable to isolated lignins in reaction mixtures. Both chemical and physical methods have been described for quantitatively determining lignin. The chemical methods are the best but they must be used with a full knowledge of the substrates being analyzed and of the limitations of the procedure being used. The best methods for determining whether lignin is present in samples are based on chemical degradations to known lignin-derived products. Three such procedures are described in the following sections, and a fourth promising new method is referenced. These procedures can also be used to gain information about the structure of the lignin in the samples. The chapter considers sample preparation, which can markedly affect the outcome of analysis.
The dinitrosalicylic acid (DNS) method gives a rapid and simple estimation of the extent of saccharification by measuring the total amount of reducing sugars in the hydrolysate. However, it is subject to interference by citrate buffer and other substances and by the differing reactivities of the various reducing sugars. These interferences become more apparent when complex substrates such as sugar cane bagasse are employed. The paper also shows how the DNS method can be adapted for use on a Technicon Autoanalyser.
Hard and softwood and wood constituent polymers (cellulose and lignin) were studied using Fourier transform infrared (FTIR) spectroscopy. The hollocellulose-to-lignin ratio was estimated for some of the timber species. The structural difference between Klason lignin isolated from softwood (Pinus roxberghii and cupressus lusitanica) and hard wood (Acacia auriculaeformis and Eucalyptus tereticornis) species was studied. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1969–1975, 1999
The pyrolysis characteristics of three main components (hemicellulose, cellulose and lignin) of biomass were investigated using, respectively, a thermogravimetric analyzer (TGA) with differential scanning calorimetry (DSC) detector and a pack bed. The releasing of main gas products from biomass pyrolysis in TGA was on-line measured using Fourier transform infrared (FTIR) spectroscopy. In thermal analysis, the pyrolysis of hemicellulose and cellulose occurred quickly, with the weight loss of hemicellulose mainly happened at 220–315 °C and that of cellulose at 315–400 °C. However, lignin was more difficult to decompose, as its weight loss happened in a wide temperature range (from 160 to 900 °C) and the generated solid residue was very high (∼40 wt.%). From the viewpoint of energy consumption in the course of pyrolysis, cellulose behaved differently from hemicellulose and lignin; the pyrolysis of the former was endothermic while that of the latter was exothermic. The main gas products from pyrolyzing the three components were similar, including CO2, CO, CH4 and some organics. The releasing behaviors of H2 and the total gas yield were measured using Micro-GC when pyrolyzing the three components in a packed bed. It was observed that hemicellulose had higher CO2 yield, cellulose generated higher CO yield, and lignin owned higher H2 and CH4 yield. A better understanding to the gas products releasing from biomass pyrolysis could be achieved based on this in-depth investigation on three main biomass components.
FT Raman spectroscopy was used for the investigation of cellulose and cellulose derivates. Lattice structures of cellulose, polymorphic modifications I and II, as well as amorphous structure were clearly identified by means of FT Raman vibrational spectra. Chemometric models were developed utilizing univariate calibration as well as methods of multivariate data analyses of the FT Raman spectral data. Cellulose properties like the degree of crystallinity XcRaman and the degree of substitution DSCMC as well as DSAC were determined.
Agricultural by-products are generally poor adsorbents of anions in solution. Therefore, modification of the by-product could enhance its anion exchange capabilities. The objective of this study was to increase the anion exchange properties of the agricultural by-product, soybean hulls, by chemical modification. Soybean hulls were quaternized with the quaternizing agent, N-(3-chloro-2-hydroxypropyl) trimethylammonium chloride, in the presence of a strongly alkaline environment. This modification increased the amount of positive charge on the hulls as evidenced by increased nitrogen content and increased uptake of anions compared with the unmodified hulls. A method to optimize the anion exchange properties of the hulls was developed. Ion exchange properties of the hulls toward anions of environmental significance, namely arsenate (As), chromate (Cr), dichromate (Cr2), phosphate (P) and selenate (Se) were determined. The modified hulls were also compared with commercial cellulose-based and synthetic anion exchange resins in their ability to remove these anions from solution. The experimental and commercial resins were also compared for their ability to remove a mixture of arsenate, chromate, dichromate and selenate from laboratory prepared solutions to levels below the maximum contaminant levels for these anions in drinking water as specified by the US Environmental Protection Agency (US EPA). Our results demonstrate that the soy hull resin is more efficient in anion removal than the commercial cellulose-based resin but not as effective as the commercial synthetic resin. Published in 2003 for SCI by John Wiley & Sons, Ltd.
Cellulose nanocrystals with rod, sphere, and network morphologies were prepared by acid hydrolysis of cotton cellulose, followed by freeze-drying. Hydrolysis with sulfuric acid introduced sulfate groups to these nanocrystal surfaces permitting their dispersion in aqueous as well as organic media, including ethanol and N,N-dimethylformamide, in a matter of seconds. Freeze-drying, on the other hand, induced mesoporosity (91.99 ± 2.57 Å average pore width) and significantly improved specific surface (13.362 m2/g) that is about 9 times of the original cellulose (1.547 m2/g). Moreover, the nanocrystals exhibited improved thermal conductivity and considerably higher (nearly 30%) carbonaceous residue, possibly due to direct solid-to-gas decomposition. These results demonstrated that a combination of surface charge introduction and fixation of mesoporosity in cellulose nanocrystals is an efficient route to prepare large quantity of high quality cellulose nanocrystals with quick re-dispersion capability for practical applications.
Starch was allowed to react thermochemically (oven versus drum drying-oven) with citric acid to potentially yield biodegradable products possessing high ion exchange capacity. Reaction variables studies were: starch type (amylose content 0-70%). pH (0.5-8.5), sodium level (0-3 moles), citric acid level (0.1-0.5 moles), reaction time, temperature (110-140°C) and sodium dihydrogen phosphate catalysis. Reaction efficiencies approaching 100% were achieved,while minimizing crosslinking and maximizing carboxyl content. Carboxyl content was determined and copper binding capacity at pH 4.5 was evaluated.
Stärkecitrat: Darstellung und Ionenaustauscher-Eigenschaften.
Stärke wurde thermochemisch (Ofen gegenüber Trommeltrocknungs-Ofen) mit Citronensäure zur Reaktion gebracht, um die potentielle Ausbeute an bioabbaubaren Produkten mit hoher Ionenaustauscher-Kapazität zu ermitteln. Die untersuchten Reaktionsvariablen waren: Stärketyp (Amylosegehalt 0-70%), pH (0.5-8.5), Natrium-Niveau (0-3Mol), Citronensäure-Niveau (0.1-0.5Mol, Reaktionszeit. Temperatur (110-140°C) und Natriumdihydrogen-Phosphat-Katalyse. Es wurden Wirkungsgrade bis nahezu 100% erreicht bei Minimierung der Vernetzung und Maximierung des Carboxylgehaltes. Der Carboxylgehalt wurde bestimmt und die Kupfer-Bindungskapazität berechnet.
The effectiveness of several pretreatments [high-power ultrasound, sulfuric acid (H(2)SO(4)), sodium hydroxide (NaOH), and ammonium hydroxide (NH(3)OH)] to enhance glucose production from insoluble fractions recovered from enzyme-assisted aqueous extraction processing of extruded full-fat soybean flakes (FFSF) was investigated. Sonication of the insoluble fraction at 144 μm(pp (peak-to-peak)) for 30 and 60s did not improve the saccharification yield. The solid fractions recovered after pretreatment with H(2)SO(4) [1% (w/w), 90°C, 1.5h], NaOH [15% (w/w), 65°C, 17 h], and NH(3)OH [15% (w/w), 65°C, 17 h] showed significant lignin degradation, i.e., 81.9%, 71.2%, and 75.4%, respectively, when compared to the control (7.4%). NH(3)OH pretreatment resulted in the highest saccharification yield (63%) after 48 h of enzymatic saccharification. A treatment combining the extraction and saccharification steps and applied directly to the extruded FFSF, where oil extraction yield and saccharification yield reached 98% and 43%, respectively, was identified.