Efficient co-production of xylooligosaccharides, furfural and reducing sugars from yellow bamboo via the pretreatment with biochar-based catalyst

Valorization of rapeseed straw through the enhancement of cellulose accessibility, lignin removal and xylan elimination using an n-alkyltrimethylammonium bromide-based deep eutectic solvent

n-Alkyltrimethylammonium bromide (CnTAB)-based deep eutectic solvent (DESs) has potential in the efficient delignification and utilization of carbohydrates in biomass. In this research, DESs containing Brønsted acid and Lewis acid were prepared with CnTAB (alkyl-chain length 12-18), organic acids and metal chlorides, and the optimal treatment conditions were acquired by pretreatment optimization. Through the pretreatment with TTAB/LCA/Fe3+ (1:4:0.0111, mol:mol:mol) (162.5 °C, 61.7 min), lignin (89.2 %) and xylan (77.9 %) were effectively eliminated, and the hydrophobicity of rapeseed straw substantially declined from 4.62 to 2.09 m2/g, acquiring the highest enzymatic saccharification efficiency of 92.5 %. The relationship of DES properties and enzymatic saccharification efficiency was explored. Additionally, hemicellulose in rapeseed straws could be efficiently transformed into furfural (3.75 g/L) and xylo-oligosaccharides (3.64 g/L). To clarify the structural and property changes brought by pretreatment, rapeseed straws were testified by FT-IR, SEM and CLSM and deeply discussed. The interaction between lignocellulose and TTAB/LCA/Fe3+ was elucidated by molecular dynamics simulations and quantum chemical calculations, explaining the effectual treatment performance and hemicellulose upgrading at the molecular level. Eventually, a potential pretreatment mechanism of TTAB/LCA/Fe3+ was proposed. This established TTAB/LCA/Fe3+ treatment holds great promise for valorization of biomass into biofuels and biobased chemicals.

Unlocking full potential of bamboo waster: Efficient co-production of xylooligosaccharides, lignin, and glucose through low-dosage mandelic acid hydrolysis with alkaline processing

Mandelic acid (MA), a natural and environmentally friendly organic acid, demonstrates high selectivity and efficiency in hydrolyzing hemicellulose, making it an excellent candidate for xylooligosaccharides (XOS) production at low acid dosages. Despite its potential, the application of MA for XOS production has not been evaluated. The study first investigated the effectiveness of MA in hydrolyzing hemicellulose in bamboo into XOS. Under optimized conditions (50 mM MA, 180 °C, 45 min), a high XOS yield of 65.9 % was achieved, with a total xylobiose and xylotriose yield of 43.5 %. Subsequent alkaline pretreatment enabled 92.1 % lignin removal from MA-pretreated bamboo. The recovered lignin exhibited a high purity of 95.2 % and retained fundamental structure and functional groups of native lignin. The resulting residue displayed enhanced crystallinity and accessibility, with reduced hydrophobicity and surface area lignin compared to untreated bamboo. At high substrate concentration of 20 %, cellulase hydrolysis resulted in a glucose conversion efficiency of 83.9 %. Overall, this integrated strategy offered an efficient approach for the co-production of valuable XOS, lignin, and glucose from bamboo. The efficient energy utilization and economic viability further highlighted the potential of this method for large-scale industrial applications, making it an attractive option for biomass valorization.

Influence of biphasic phenoxyethanol-alkaline pretreatment on the correlation between inter-structure and enzymatic hydrolysis in bamboo residues

The effective promotion of delignification (67.6 %) and xylan removal (44.8 %) from bamboo residues using a 2-phenoxyethanol/sodium hydroxide solution (P/A) system is demonstrated, while simultaneously enriching oligosaccharides contents of the pre-hydrolysate to 10.2 g/L. Increasing the P/A ratio from 0:1 to 4:1 improves the enzymatic digestibility of the substrates from 55.7 % to 70.1 % at 100 °C and from 73.8 % to 83.7 % at 120 °C. Furthermore, partial correlation analysis demonstrates that the physiochemical properties, including delignification, xylan removal, and crystallinity, show a significant positive correlation with enzymatic hydrolysis efficiency. Higher temperatures and P/A ratios during alkaline biphasic pretreatment promote the shrinkage of plant cells and delignification, with temperature being a particularly significant driver. These findings provide valuable insights into the alkaline and biphasic pretreatment of biomass and facilitate the optimization of the bio-refining system.

Acid-catalyzed transformation of orange waste into furfural: the effect of pectin degree of esterification

The transformation of biomasses from agro-industrial waste can significantly impact the production of green chemicals from sustainable resources. Pectin is a biopolymer present in lignocellulosic biomass as Orange Peel Waste (OPW) and has possibilities for making platform compounds such as furfural for sustainable chemistry. In this work, we studied the transformation to furfural of OPW, pectins, and D-galacturonic acid (D-GalA), which is the main component (65 wt%) of pectin. We analyzed pectins with different degrees of esterification (45, 60 and 95 DE) in a one-pot hydrolysis reaction system and studied the differences in depolymerization and dehydration of the carbohydrates. The results show that the production of furfural decreases as the DE value increases. Specifically, low DE values favor the formation of furfural since the decarboxylation reaction is favored over deesterification. Interestingly, the furfural concentration is dependent upon the polysaccharide composition of pentoses and uronic acid. The obtained concentrations of furfural (13 and 14 mmol/L), D-xylose (6.2 and 10 mmol/L), and L-arabinose (2.5 and 2.7 mmol/L) remained the same when the galacturonic acid was fed either as a polymer or a monomer under the same reaction conditions (0.01 M SA, 90 min and 433 K). OPW is proposed as a feedstock in a biorefinery, in which on a per kg OPW dry basis, 90 g of pectin and 15 g of furfural were produced in the most favorable case. We conclude that the co-production of pectin and furfural from OPW is economically feasible.

Effect of alkali treatment on enzymatic hydrolysis of p-toluenesulfonic acid pretreated bamboo substrates

The comprehensive separation and utilization of whole components of lignocellulosic materials has received extensive attention in present research. This study focused on the efficacy of alkali treatment for enzymatic saccharification of cellulose based on p-toluenesulfonic acid (p-TsOH) pretreated bamboo substrate. The results showed that the cellulose to glucose conversion yield was 94.69 % under optimized conditions of 0.4 g NaOH/g, 160 °C and 4 h (soaked), which after only 6 h enzymatic hydrolysis time. Alkali lignin recovery was 88.51 %, with potential for conversion to lignin derivatives. The yield of hemicellulose in the pretreated filtrate was 51.85 % after the 4th cycling reuse of p-TsOH. This work has borrowed the advantages of p-TsOH pretreatment of depolymerized hemicellulose from bamboo, combined with a low-priced weak alkali secondary treatment method, which can be effectively applied to the co-production of lignin, xylooligosaccharide, xylose and glucose, and the whole process is green and economically sustainable.

Integrated metabolomics and transcriptomics revealed the anti-constipation mechanisms of xylooligosaccharides from corn cobs

Xylooligosaccharides (XOSs) have recently garnered interest for their potential as an anti-constipation agent. In this study, we investigated the effects of XOSs derived from corn cobs on constipation in mice through a comprehensive analysis of both the metabolome and transcriptome. Our multi-omics approach revealed that XOSs primarily modulated butanoate metabolism and steroid hormone biosynthesis pathways, as well as key signaling pathways such as PPAR and NF-kappa B. Notably, we observed a decrease in inflammatory biomarker expression and an elevation of butyric acid metabolite levels with XOSs treatment. A deeper analysis of gene expression and metabolite alterations highlighted significant changes in genes encoding critical enzymes and metabolites involved in these pathways. Overall, these findings underscore the considerable potential of XOSs derived from corn cobs as a dietary supplement for effectively alleviating constipation.