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Renewable hemicellulose with a unique structure exhibits a wide range of potential applications. However, it has been a formidable challenge to isolate hemicellulose with an intact structure from lignocellulosic materials. In this study, LiBr·3H2O (LBTH) was used as a green solvent for the effective fractionation of hemicellulose from bleached hardwood kraft pulp (BHKP) under mild conditions (25–85 °C). It was found that hemicellulose in BHKP can be dissolved in LBTH with ease and high selectivity owing to the breaking of hydrogen bonds between hemicellulose and cellulose, and the dissolved hemicellulose can be regenerated with a high degree of polymerization (DP) in the range of 240–264 using ethanol precipitation. The highest removal rate of hemicellulose from BHKP was as high as 95.2%, and the corresponding yield of pure hemicellulose reached 84.3%. Moreover, simultaneously obtained undissolved cellulose pulp through LBTH treatment had a high content of α-cellulose (96.7%), high DP (880), and trace levels of Fe (2 ppm), which met the standard requirement for dissolving pulp for the production of lyocell. In addition, LBTH can be easily recycled to guarantee a green and sustainable process. This work provides a new approach for highly selective fractionation of hemicellulose and cellulose from commercial BHKP based on an efficient and environmentally friendly LBTH treatment, which could be very promising for better valorization of hemicellulose and cellulose in many advanced applications. [ABSTRACT FROM AUTHOR]

Hemicellulose-based hydrogels are three-dimensional networks formed by crosslinking hydrophilic polymers with tunable swelling behavior,acceptable biocompatibility and mechanical properties,and have received much attention in the field of soft materials especially in hemicellulose-based materials.Herein,recent advances and developments in hemicellulose-based hydrogels were reviewed.The preparation methods,mechanism of their gelation process,and the performance of the hemicellulose-based hydrogels were presented from both chemical and physical cross-linking approaches,while the differences in various initiation systems such as light,enzyme,microwave irradiation and glow discharge electrolysis plasma in chemical cross-linking were compared.The latest applications of hemicellulose-based hydrogels in drug-controlled release,wound dressing,water purification,3D printing dispersions, etc,were introduced, respectively.Finally,the challenges in the development of hemicellulose-based hydrogels were summarized briefly and future prospect was also given,which provides a reference for the synthesis of new hemicellulose-based hydrogels.

Hemicellulose-based hydrogels are three-dimensional networks formed by crosslinking hydrophilic polymers with tunable swelling behavior,acceptable biocompatibility and mechanical properties,and have received much attention in the field of soft materials especially in hemicellulose-based materials.Herein,recent advances and developments in hemicellulose-based hydrogels were reviewed.The preparation methods,mechanism of their gelation process,and the performance of the hemicellulose-based hydrogels were presented from both chemical and physical cross-linking approaches,while the differences in various initiation systems such as light,enzyme,microwave irradiation and glow discharge electrolysis plasma in chemical cross-linking were compared.The latest applications of hemicellulose-based hydrogels in drug-controlled release,wound dressing,water purification,3D printing dispersions, etc,were introduced, respectively.Finally,the challenges in the development of hemicellulose-based hydrogels were summarized briefly and future prospect was also given,which provides a reference for the synthesis of new hemicellulose-based hydrogels.

Despite rapid development, oil spill agents still suffer from limitations of high cost, low adsorption ability, and non‐degradability. Herein, the alkaline lignin (AL) and hemicelluloses (xylan, Xyl) are transferred into low‐cost, green, and eco‐friendly powder gelators, featuring congealing oil ability, easy collection, and oil spill recovery. The AL and Xyl can form gels in the presence of excessive epichlorohydrin (ECH)/sodium hydroxide (NaOH) solution and subsequently self‐collapse into brittle solid when rinsed in water. After silylation treatment, the resultant powder exhibits high efficiency to congeal, a series of floating oils, as well as the great oil recovery ability. The easy availability of pulping byproducts, scalable preparation method, and excellent spill oil treatment ability hold promise for developing new bio‐based oil spill agents. [ABSTRACT FROM AUTHOR]

Improving the mechanical performance of hemicellulose-based hydrogel is an enormous challenge. Here, we propose a new strategy to achieve the hemicellulose-based hydrogels with superior mechanical performance through chain extension and semi-interpenetrating polymeric networks (semi-IPN). Xylan, known as the main type of hemicelluloses in angiosperms, is successfully modified to increase molecular weight by reductive amination reaction, overcoming the major limitation of brittleness. Then, the chemical network is obtained by graft copolymerizing acrylic acid (AA) with cross-linking agent N,N′-methylenebisacrylamide (MBA) in the presence of chain extended xylan (CEX). With the further introduction of ferric ions, a physical network is constructed via metal–ligand interactions. Such a xylan-based semi-IPN hydrogel shows excellent mechanical properties with a fracture tensile stress of 1.4 MPa, compression stress of 0.59 MPa, and the elongation at break of 1136%. In addition, the hydrogel also exhibits fine water absorbency (213.6 g/g) and high electrical conductivity (4.76 × 10–3 S/m). We anticipate that the resultant xylan-based semi-IPN hydrogels will open up a new approach for the design of high performance hemicellulose-based soft materials. [ABSTRACT FROM AUTHOR]

Neosinocalamus affinis hemicelluloses were extracted with pure DMSO and 3% NaOH in sequence. The DMSO- and NaOH-extracted hemicelluloses were then successively fractionated by gradient ethanol precipitation. NaOH-extracted hemicellulosic fractions with different branch degree could be separated by gradient ethanol precipitation, while DMSO-extracted hemicellulosic fractions could not. FT-IR spectra showed that DMSO-extracted fractions have more complete structure, while NaOH-extracted fractions have no acetyl at all. The FT-IR and NMR revealed that the DMSO-extracted Neosinocalamus affinis hemicelluloses were 4-O-methyl-glucuronoarabinoxylans consisting of a linear (1→4)-β-D-xylopyranosyl backbone with branches at O-2,3 of acetyl, O-2 of 4-O-methyl-a-D glucuronic acid, and O-3 of arabinose. [ABSTRACT FROM AUTHOR]

A novel hybrid hydrogel was prepared from hemicelluloses, polyvinyl alcohol, and chitin nanowhiskers by the freeze-thaw technique. The hydrogel was characterized by Fourier-transform infrared (FT-IR) spectrometry, scanning electron microscopy, X-ray diffraction analysis, cross-polarization (CP)/magic-angle spinning (MAS) C nuclear magnetic resonance (NMR), and swelling property and compressive strength measurements. Atomic force microscopy images of chitin implied that the size of whiskers reached nanometer level with average length of about 200 nm and width of 40 nm. The FT-IR and NMR results indicated that physical cross-linking rather than chemical reaction occurred during the gelation process. The mechanical properties of the hydrogels were significantly improved with increasing proportion of chitin nanowhiskers, with the highest compressive stress of 9.6 MPa being found for Gel-0.5. The results showed that the repeated freeze-thaw cycles induced physical cross-linking of packed chains by hydrogen bonds among the polymers, and the concentration of chitin nanowhiskers affected the hydrogel morphology and properties. It is suggested that hydrogels with good mechanical properties can be successfully prepared by this physical method, offering promise for tissue engineering applications. [ABSTRACT FROM AUTHOR]

Abstract: Hemicelluloses were extracted from holocellulose of bamboo by alkaline treatment. The phosphorylated poly(vinyl alcohol) (P-PVA) samples with various substitution degrees were prepared through the esterification of PVA and phosphoric acid. A series of hydrogels of semi-interpenetrating polymeric networks (semi-IPN) composed of hemicelluloses-g-poly(acrylic acid) (HM-g-PAA) and the phosphorylated poly(vinyl alcohol) (P-PVA) were prepared by radical polymerization using potassium persulphate (KPS) as initiator. The HM-g-PAA networks were crosslinked by N,N-methylenebisacrylamide (MBA) as a crosslinking agent in the presence of linear P-PVA. FT-IR results confirmed that the hydrogels comprised a porous crosslink structure of P-PVA and HM with side chains that carried carboxylate and phosphorylate groups. SEM observations indicated that the incorporation of P-PVA induced highly porous structure, and P-PVA was uniformly dispersed in the polymeric network. The interior network structures of the semi-IPN matrix became more porous with increasing P-PVA. The TGA results showed that the thermo-decomposing temperature and thermal stability were increased effectively for intruding the chain of P-PVA. The maximum equilibrium swelling ratio of hydrogels in distilled water and 0.9wt% sodium chloride solutions was up to 1085gg−1 and 87gg−1, respectively. The compressive strength increased with increasing the MBA/HM and P-PVA/HM ratios, and decreased with the increment of AA/HM ratio. [Copyright &y& Elsevier]

Abstract: Xylooligosaccharides (XOS) were prepared from xylan-rich hemicelluloses isolated by potassium hydroxide from sugarcane bagasse by hydrolysis with crude xylanase secreted by Pichia stipitis. Hydrolysis for 12h produced XOS with a maximum yield of 31.8%, equivalent to 5.29mgmL−1 in the hydrolyzate. XOS with degrees of polymerization (DP) from 2 to 4 (xylobiose, xylotriose, and xylotetraose) were the major components in the hydrolysates, whereas the oligosaccharides with higher DP of 5–6 (xylopentaose and xylohexose) showed a constant low level. FT-IR and NMR (1H, 13C, HSQC) demonstrated that XOS contained Araf and 4-O-Me-α-d-GlcpA residues. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay showed that the XOS exhibited concentration-dependent antioxidant activity. The results obtained indicate that the XOS produced from sugarcane bagasse can be employed in food-related applications. [Copyright &y& Elsevier]

Abstract: Hemicelluloses are types of plant cell wall polysaccharides, and the world''s second most abundant renewable polymers after cellulose in lignocellulosic materials. They represent a type of hetero-polysaccharide with complex structure containing glucose, xylose, mannose, galactose, arabinose, rhamnose, glucuronic acid, and galacturonic acid in various amounts, depending on the source. Hemicelluloses are usually bonded to other cell-wall components such as cellulose, cell-wall proteins, lignin, and phenolic compounds by covalent and hydrogen bonds, and by ionic and hydrophobic interactions. This paper provides a review on hemicelluloses from lignocellulosic materials, especially in regard to their isolation and purification methods, and bioconversion. Current isolation and purification strategies are summarized, including: alkali peroxide extraction, organic solvent extraction, steam explosion, ultrasound-assisted extraction, microwave-assisted extraction, column chromatography, and membrane separation. In addition, the bioconversion of hemicelluloses including pretreatment, enzymatic hydrolysis, and fermentation are discussed. [Copyright &y& Elsevier]

Hemicellulosic polymers A and B were isolated from Populus gansuensis by extracting the chlorite-delignified residue with 10% KOH. Fractional precipitation of hemicellulose B by graded ethanol resulted in six subfractions varying in yield, molecular size distribution, and sugar composition. Macromolecular and more linear hemicellulosic polymers with higher yields were preferentially precipitated in relatively lower ethanol concentrations, while more branched and complex hemicellulosic polymers with lower molecular weights were obtained in relatively higher ethanol concentrations. Chemical and spectral evidence suggested that H30 subfraction obtained by 30% ethanol precipitation was assumed to be 4- O-methyl- D-glucurono- D-xylans, with 4- O-methyl- D-glucuronic acid linked to C-2 of (1→4)-β- D-xylan. On average for every six D-xylopyranosyl residues, there is one 4- O-methyl- D-glucuronic acid group. Hemicellulosic subfraction H75 precipitated at the ethanol concentration of 75% was more branched, and presumed to be heterogeneous mixture of arabinoglucurnoxylan and galactoglucomannan. In addition, the thermal stability of the linear large molecular hemicellulosic subfraction H30 appeared higher than the branched subfraction H75. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

Abstract: Seven hemicellulosic fractions were extracted with 10% KOH from delignified sugarcane bagasse for 10h at 20, 25, 30, 35, 40, 45, and 50°C, respectively. Chemical composition and structural features of all the fractions were investigated by a combination of HPAEC, GPC, FT-IR, 1D (1H, 13C) and 2D (HSQC) NMR spectra, and TGA-DTA. Notable differences in the molecular weights were observed that the fractions extracted at 20°C, 25°C, and 30°C showed relatively lower molecular weights (68, 400–76, 900gmol−1) and the extraction at elevated temperatures from 35 to 50°C yielded the hemicellulosic populations of somewhat higher M w (80, 400–93, 300gmol−1). However, the differences in the yield, chemical composition, structural features and thermal stability were much less pronounced in this study. The results also suggested that all the hemicellulosic polymers had a backbone of (1→4)-β-d-xylan and mainly substituted with (1→2) and (1→3)-linked arabinofuranosyl residues, and also with 4-O-methyl-d-glucuronic acid linked to O-2 of the backbone. [Copyright &y& Elsevier]

Abstract: Water and alkali-soluble polysaccharides, isolated by sequential extractions with distilled water, 0.5% and 1% NaOH, 60% ethanol containing 1% NaOH, and 3%, 5% and 8% NaOH, were prepared at 60°C for 3h from dewaxed bamboo Phyllostachys incarnata Wen. The yields of the seven fractions together accounted for 80.1% of total available hemicellulosic polysaccharides. Sugar composition studies showed that the water-soluble polysaccharides consisted mainly of glucose units, while xylose, arabinose and glucuronic acid were the major sugars in alkali-soluble hemicelluloses. Moreover, the molecular weights of these polymers varied between 3760 and 36,000g/mol as revealed by GPC. Furthermore, the structure of the hemicellulosic fraction extracted with 3% NaOH was determined by 1H and 13C NMR spectroscopy along with 2D HSQC. It was found that the bamboo hemicelluloses were O-acetyl-(4-O-methylglucurono)-arabinoxylans, and the structural element could be identified as below: 1,4-β-D-[2-O-Ac][2,3-di-O-Ac][4-O-Me-α-D-GlcpA-(1→2)][α-L-Araf-(1→2)(1→3)]-xylp. [Copyright &y& Elsevier]

Abstract: Sequential treatments of dewaxed Caragana korshinskii with dimethyl sulfoxide and dioxane-triethylamine (9:1, v/v) at 80°C for 5h, saturated barium hydroxide, 1M potassium hydroxide and 1M sodium hydroxide at 50°C for 5h, and 3M potassium hydroxide at 50°C for 4h released 9.9%, 12.1%, 19.2%, 27.7%, 13.2% and 12.9% of the original hemicelluloses, respectively. The DMSO-soluble and four alkali-soluble hemicellulosic fractions contained higher amounts of xylose (73.6–91.5%), but were lower in rhamnose (0.5–2.3%) and arabinose (2.8–17.6%) than dioxane-triethylamine (9:1, v/v) soluble hemicellulosic fraction, in which xylose (37.9%), rhamnose (25.9%) and arabinose (25.0%) were the major sugar components. In comparison, the molecular-weight analysis showed that hemicelluloses were substantially degraded with a value of 13,930gmol−1 under the organic alkaline extraction condition (dioxane-triethylamine, 9:1) used, whereas saturated Ba(OH)2 treatment favored the solubilization of macromolecular hemicelluloses (69,910gmol−1). It is confirmed that the hemicelluloses from C. korshinskii are (1→4)-linked β-d-xylans with l-arabinofuranosyl group attached based on both 1H and 13C NMR spectra. [Copyright &y& Elsevier]

Abstract: Caragana korshinskii hemicelluloses were isolated with 10% KOH at 25°C for 10h from the delignified materials. The alkali-extractable hemicelluloses were then successively sub-fractionated by graded precipitation at final ethanol concentrations of 10%, 20%, 30%, 45%, 60%, and 80%, respectively. Neutral sugars and molecular weight analyses of the six hemicellulosic subfractions revealed that the molecular weights and the distribution of branches along the xylan backbone are different among the hemicellulosic fractions obtained in various ethanol concentrations. The less branched hemicelluloses with large molecules were precipitated in lower ethanol percentages, while with the increasing ethanol concentrations, more branched hemicelluloses with low molecular weights were obtained. 1H and 13C NMR studies revealed that the hemicellulosic subfraction precipitated at an ethanol concentration of 45% had a backbone of d-xylose residues and were branched mainly through 4-O-methyl-α-d-glucopyranosyl units. [Copyright &y& Elsevier]

Abstract: Water- and alkali-soluble hemicelluloses isolated from dewaxed sugarcane bagasse were sub-fractionated on DEAE-cellulose-52 chromatography and obtained six hemicellulosic sub-fractions by eluting with water, 0.1M and 0.3M NaCl aqueous solution, respectively. Sugar composition and molecular weight analysis revealed that the lower molecular weight (14,180–43,590gmol−1) and more branches of hemicelluloses could be extracted by the hot water, which are rich in glucose, galactose, and xylose, while the higher molecular weight (75,430–138,170gmol−1) and more linear hemicelluloses were able to be dissolved into 1% NaOH aqueous solution, which are rich in xylose, principally resulting from l-arabino-(4-O-methyl-glucurono)-d-xylans. In addition, it was found that with increasing the concentration of NaCl (aqueous), the hemicellulosic sub-fractions with both higher arabinose to xylose ratio and higher molecular weight were eluted. Based on the FT-IR, sugar composition and 1H and 13C NMR comparative studies, the alkali-soluble hemicellulosic sub-fractions had a classical structure, with a backbone of β-(1→4)-linked xylosyl residue substituted with arabinose at C–2 and/or C–3 of main chain, whereas the difference may occur in the distribution of branches along the xylan backbone. [Copyright &y& Elsevier]

Abstract: In this work the application of different hemicellulosic derivatives including different degrees of substitution (DS) cationic hemicelluloses and carboxymethyl hemicelluloses in sulfate kraft pulp were investigated in detail. It was found that cationic hemicelluloses and carboxymethyl hemicelluloses could improve the physical properties of hand sheets, while the cooperation of cationic hemicelluloses and carboxymethyl hemicelluloses could enhance sharply the physical properties of hand sheets. When the dosages of cationic hemicelluloses with DS of 0.37 and carboxymethyl hemicelluloses with DS of 0.35 were 1.0% and 1.0% (based on dry pulp weight), respectively, the physical properties of hand sheets was significantly improved, breaking lengthen and tear index of hand sheets increased by 21.1% and 54.6% compared with the control hand sheets without any additives added. The fiber intertexture of the hand sheets was observed by SEM. The results indicated that hemicelluloses could be used as the source for the production of wet-end additives in papermaking, which might represent an important strategy for sustainable use of the agricultural residue. [Copyright &y& Elsevier]

Abstract: Hemicellulose-based hydrophobic biomaterials with degrees of substitution ranging from 0.46 to 1.54 were synthesized under mild conditions in homogeneous media (N,N-dimethylformamide–lithium chloride) by reacting the native wheat straw hemicellulosic polymers with lauroyl chloride using 4-dimethylaminopyridine as a catalyst. Other catalysts such as N-bromosuccinimide, N-methyl pyrrolidine, N-methyl pyrrolidinone, and pyridine were also investigated. Under optimum reaction conditions (2equiv of lauroyl chloride and triethylamine per hydroxyl group, 5% 4-dimethylaminopyridine, 40°C, 35min), a high DS value of 1.54 was obtained. The biomaterials were characterized by FT-IR spectroscopy and 13C NMR spectroscopy as well as by thermal analysis. The results showed that the lauroylation occurred preferably at the C-3 hydroxyl group of β-d-Xylp units in the hemicelluloses, and the thermal stability of the hydrophobic polymers increased by esterification. [Copyright &y& Elsevier]

Abstract: A series of novel water-soluble hemicellulosic derivatives, containing carbamoylethyl and carboxyethyl groups, were heterogeneously synthesized from wheat-straw hemicelluloses with acrylamide (AA) under alkaline conditions. The factors such as reaction temperature, reaction time, molar ratio of catalysis to xylose unit in hemicelluloses and molar ratio of acrylamide to xylose unit in hemicelluloses, were investigated. The average degree of substitution (DS) was calculated by 1H NMR spectroscopy. DS values up to 0.23 in a one-step synthesis of hemicelluloses derivatives were obtained. Under optimum conditions (60°C, NaOH to xylose unit in hemicelluloses molar ratio of 0.8, AA to xylose unit in hemicelluloses molar ratio of 8.0, reaction time of 1h) an expected ratio of carbamoylethyl group to carboxyethyl group of 4.8 in the hemicellulosic derivatives was obtained. The structural features of the hemicellulosic derivatives were characterized by FTIR, NMR spectroscopy, and by elemental analysis. The current work provides a facile method for the synthesis of hemicellulose derivatives with bifunctional groups, which could be used as wet-end additives in the papermaking industry. [Copyright &y& Elsevier]

Wood auto-hydrolysates (WAH) are obtained in the pulping process by the hydrothermal extraction, which contains lots of hemicelluloses and slight lignin. WAH and chitosan (CS) were introduced into this study to construct WAH-based films by the casting method. The FT-IR results revealed the crosslinking interaction between WAH and CS due to the Millard reaction. The morphology, transmittance, thermal properties and mechanical properties of composite WAH/CS films were investigated. As the results showed, the tensile strength, light transmittances and thermal stability of the WAH-based composite films increased with the increment of WAH/CS content ratio. In addition, the results of oxygen transfer rate (OTR) and water vapor permeability (WVP) suggested that the OTR and WVP values of the films decreased due to the addition of CS. The maximum value of tensile strengths of the composite films achieved 71.2 MPa and the OTR of the films was low as 0.16 cm3·μm·m−2·24 h−1·kPa−1, these properties are better than those of other hemicelluloses composite films. These results suggested that the barrier composite films based on WAH and CS will become attractive in the food packaging application for great mechanical properties, good transmittance and low oxygen transfer rate. [ABSTRACT FROM AUTHOR]

It is desirable to develop products comprised of biodegradable components from green resources or renewable waste due to a shortage of fossil fuel. Wood auto-hydrolysates (WH) are generated in the hydrothermal treatment of the pulping process, which contains large amounts of hemicelluloses and some lignin. In this work, a green and facile route similar to paper making is proposed to convert WH to value-added nanocomposite films. WH was combined with montmorillonite (MMT) as the basic components together with a small quantity of graphene oxide (GO) to produce a ternary, bioinspired nanocomposite film with high strength and fire resistance properties. GO was initially introduced to fabricate the WH-MMT-GO nanocomposites, the interfacial interaction between WH, MMT, and GO was enhanced by the synergistic effect of hydrogen and covalent bonds. The nanocomposite film WH-MMT-rGO (F 0.8%rGO ) with only 0.8 wt% rGO exhibited promising features, such as a good thermal stability, and a high strength of 124 MPa, which was better than other hemicellulose-based films or wood auto-hydrolysate based films. The combustion behavior of WH-MMT-GO films was determined by microscale combustion calorimeter (MCC), and the results suggested the films had excellent fire resistance, where the peak heat release rate (PHRR) of the films was reduced by more than 90% compared to the neat WH. Furthermore, the hemicellulose-based films are reported to be hydrophilic, while the WH-MMT-rGO films proved to be hydrophobic due to the introducing of rGO. The proposed synthetic strategy could make the wood auto-hydrolysate useful for fabrication of fire-protective films, coatings, packaging, etc. [ABSTRACT FROM AUTHOR]

Polymers with high conductivity and cross-linking ability are ideal materials for the preparation of conductive hydrogels for application in wearable electronic devices. However, the fabrication of conductive polymer-incorporated hydrogels with good synergistic properties remains a great challenge due to the hydrophobicity and opacity of conjugated π conductive polymers. In this study, a multifunctional hybrid hydrogel was prepared by incorporating hemicellulose-decorated polypyrrole (H/PPY), polyvinyl alcohol (PVA), and tannic acid (TA) into a polyacrylamide (PAM) network. The addition of excess ammonium persulfate (APS) in the process of gelation not only initiated the polymerization of PAM but also resulted in the change of the hydrogel from opaque to transparent by continuously breaking and reducing the size of the PPY particles. The hybrid hydrogel exhibited high transparency and conductivity, good adhesion ability and mechanical performance, and high resistance strain sensitivity and could accurately monitor the strain signals of the index finger and elbow flexion and pulse beat during rest and exercise, which has promising potential for use in wearable or implantable smart sensor devices, electronic skins, and artificial intelligence applications. [Display omitted] • Hemicellulose-decorated polypyrrole was synthesized to prepare hybrid hydrogels. • The hydrophilic hemicelluloses promote a more homogeneous crosslinked network. • The hydrogel has a high transmittance of 79.6 % and a good conductivity of 3.12 S/m. • The hydrogel exhibits good self-adhesion ability and high strain sensitivity. [ABSTRACT FROM AUTHOR]

Highlights: [•] Rod-like chitin nanowhiskers were produced successfully by acid treatment. [•] Hydrogels were prepared by freeze–thaw technique with the three polymers. [•] The designed hydrogels had higher thermal stability and compressive strength. [•] The hydrogels could be a promising candidate for tissue engineering applications. [ABSTRACT FROM AUTHOR]

In recent years, deep eutectic solvents (DESs) are used for enhancing the enzymatic digestibility and lignin fractionation in pretreatment, while hemicellulosic fraction receives scant attention. Herein, we report a novel approach of applying alkaline deep eutectic solvents (ADESs) for dissociating hemicelluloses from woody biomass. Among these ADESs, choline chloride-monoethanolamine (C-M) was the most efficacious medium for deconstructing the recalcitrant structure of poplar and 63.3% of hemicelluloses was obtained at 80 °C. Structure analysis showed that the ADESs-extracted hemicelluloses retained partial of O -acetyl groups. Different ADESs could be used to obtain hemicelluloses with various degrees of branching. Furthermore, the enzymatic digestibility of cellulose was significantly increased by 6.6 times compared to that of the untreated poplar under the optimum conditions (C-M, 140 °C). This work provides a view on the dissociation behavior of hemicelluloses during ADESs pretreatment, which would be beneficial for devising DESs toward effective fractionation and comprehensive utilization of biomass. • Four alkaline deep eutectic solvents (ADESs) were applied to deconstruct poplar. • Choline chloride-monoethanolamine (C-M) caused the highest hemicellulose yields. • The dissociation behavior of hemicelluloses was elucidated. • Cellulose digestibility was increased by 6.6 times after C-M pretreatment. [ABSTRACT FROM AUTHOR]

Abstract: Hemicelluloses isolated from sugarcane bagasse were converted to carboxymethyl hemicelluloses (CMH) by carboxymethylation using sodium monochloroacetate and sodium hydroxide in ethanol/water medium. The reaction was performed under various temperatures, times, times of alkaline activation, the ways of the addition of alkali, and the amounts of sodium hydroxide and sodium monochloroacetate. The product had the maximum degree of substitution (DS) of 0.56. The structure of the resulting polymers was characterized with Fourier transform infrared (FT-IR) and 13C nuclear magnetic resonance (NMR) spectroscopies. Destructive methods such as thermal analysis and non-destructive techniques such as gel permeation chromatography (GPC) were used to characterize the carboxymethyl hemicellulose preparations. It was found that a significant degradation of the polymers occurred during carboxymethylation. The thermal stability of carboxymethyl hemicelluloses was higher than that of the native hemicelluloses. [Copyright &y& Elsevier]

Biomass is one of the powerful alternatives to petroleum-based packaging materials. Herein, carboxymethyl hemicellulose (CMH) based films (CPF) were prepared using a convenient strategy. The chains of CMH provided the necessary supporting matrix, and the aminopropyl polyhedral oligomeric silsesquioxane (POSS-NH 2) regulated the thermal and barrier properties of the CPF. The secondary amide groups and hydrogen bond were appeared in chemical structure, and SEM-EDS results indicated the preferable dispersion and compatibility of POSS-NH 2 in CPFs. The thermal degradation temperature (T onset > 260 °C), the coefficient of linear thermal expansion and glass transition temperature (T g > 130 °C) have been improved by introduction of POSS-NH 2. The tensile strength of CPF showed a higher level of 39.43 MPa with the POSS-NH 2 loading of 20 wt%, which was 18.8 % higher than that of CMH film. More importantly, water vapor barrier property of films almost improved by two times, and its value is reduced to 18.82 g m−2 h−1. The shelf life of blueberry was effectively extended by the CPF coating for one week compared with commercial PE film. Therefore, CPF films displayed effective thermal performances, water vapor barrier characteristic and biodegradability, which might be exploited in packaging material for food application. [Display omitted] • Use of carboxymethylated bamboo hemicellulose for biodegradable films • POSS-NH 2 were cross-linked with CMH films by amide bond. • The comprehensive thermal performances of the CMH films have been improved. • Excellent water vapor barrier property has the application prospect for packaging. [ABSTRACT FROM AUTHOR]

Selective fractionation of hemicelluloses is of great significance for realizing high-value application of hemicelluloses and comprehensive utilization of lignocellulosic biomass. Tetramethylammonium hydroxide (TMAH) solvent has been confirmed as a promising solvent to selectively fractionate hemicelluloses from holocellulose. Herein, TMAH solvent was adopted to pretreat poplar thermomechanical pulp (PTMP) for the selective fractionation of hemicelluloses and enhancement of enzymatic hydrolysis performance of residues. The maximal hemicelluloses yield (65.0 %) and excellent cellulose retention rate (93.3 %) were achieved after pretreatment by the 25 wt% TMAH solvent, while the delignification was only 33.9 %. The hemicelluloses fractions could be selectively fractionated with high molecular weights (109,800–118,500 g/mol), the contents of Klason lignin in them were low (3.2–5.9 %), and the dominating structure of them was 4- O -methylglucurono- β -D-xylan. Compared to the H 2 SO 4 and NaOH methods, the hemicelluloses fractionated by TMAH method exhibited higher yields, more complete structures and higher molecular weights. Furthermore, the crystalline structure of cellulose practically remained stable, and the highest yield of enzymatic hydrolysis glucose was 57.5 %, which was 3.3 times of that of PTMP. The fractionation effectiveness of TMAH solvent was not significantly reduced after repeatedly recycling. This work demonstrated TMAH solvent could selectively fractionate hemicelluloses from PTMP and efficiently promote sustainable poplar-based biorefinery. • TMAH could selectively fractionate hemicelluloses from PTMP at room temperature. • Hemicelluloses showed a relatively good homogeneity in the form of macromolecules. • The contents of Klason lignin in hemicelluloses fractions were low (3.2–5.9 %). • The residues represented excellent cellulose retention rates (>93.3 %). • TMAH solvent exhibited recyclability for hemicelluloses fractionation. [ABSTRACT FROM AUTHOR]

A renewable, efficient, and low-cost material is essential for adsorbing water pollution, such as dyes and heavy metal ions pollution. Here in, we demonstrate an aerogel to remove the dyes from water based on hemicellulose. The dialdehyde hemicelluloses (DAH) were synthesized by oxidation of hemicellulose extracted from straw with NaIO 4. The hydrogels were prepared based on the dialdehyde hemicellulose and chitosan-Fe 3 O 4 composite by the Schiff's base reaction, which were processed with vacuum freeze-drying technique to obtain aerogels. It was found that hydroxyl groups at C 2 and C 3 of hemicellulose were oxidized to aldehyde groups after modification, and the content of aldehyde group was 5.57 mmol/g. The maximum compress strength of aerogel was 0.37 MPa, and the maximum absorption capacity of Congo red dye was 137.74 mg/g. Aerogels with Fe 3 O 4 exhibited magnetism which enables the aerogels to easily recycle. Meanwhile, the thermal stability, mechanical properties of the aerogels and its adsorption property to Congo red dye could be improved directly by the addition of Fe 3 O 4. • Dialdehyde hemicelluloses were prepared successfully. • Aerogels were obtained by Schiff-base and hydrogen bonds. • Aerogels possessed excellent absorption property. [ABSTRACT FROM AUTHOR]

• Electroactive carboxyl terminated aniline pentamer was synthesized. • Conductive hemicellulose hydrogels (CHHs) were manufactured by one-pot reaction. • CHHs possessed a stable macro-porous structure and tunable swelling behavior. • Conductivity of CHHs tuned by carboxyl terminated aniline pentamer contents. The conductive hemicellulose hydrogels (CHHs) were achieved by incorporating carboxyl terminated aniline pentamer (CTAP) into the hydrophilic xylan-rich hemicellulose networks with epichlorohydrin. CHHs were obtained by facile one-pot reaction in water at ambient temperature. The successful synthesis of CTAP was confirmed by FT-IR, 1H NMR, and UV–vis spectra. All the hydrogels reached their equilibrium-swollen state within 12 h. The morphology and the thermal stability of CHHs were adjusted by the addition of CTAP. The conductivities of CHHs could also be tuned from 8.92 × 10−5 to 2.11 × 10−3 S/m by adding the blending amounts of the CTAP from 0 to 50% mass ratio while simultaneously altering the equilibrium swelling ratio from 28.1 to 15.8. CHHs showed homogeneous porous structure, tunable swelling behavior, controllable conductivity, and good thermal stability. These results highlight that CHHs are attractive candidates to be used in biomedical applications. [ABSTRACT FROM AUTHOR]

Eucalyptus wood was pretreated with an integrated process based on hydrothermal and alkaline pretreatments. The structural changes of hemicelluloses during the pretreatments and the components of the hydrolysates were comprehensively characterized. Sugar and spectral analyses indicated that the hemicelluloses remained in the residues obtained at hydrothermal pretreatment under low temperatures were mainly composed of a (1 → 4)- β -D-Xyl p backbone with 4- O -methyl- α -D-glucuronic acids attached at O -2 of the xylose together with various monosaccharides of rhamnose, arabinose, galactose, glucose, and mannose. The pretreatments resulted in serious degradation of hemicelluloses at high pretreatment temperatures. The distribution changes of the hemicelluloses in the cell walls during the integrated pretreatments were detected by Confocal Raman Microscopy, which revealed that the dissolution of hemicelluloses in different morphological regions was inhomogeneous, and the a large portion of hemicelluloses were removed from the secondary cell wall regions during the pretreatments. Unlabelled Image • Hydrothermal and alkaline pretreatments were proposed to treat Eucalyptus wood. • The H 0 and H 170 have a linear backbone of (1 → 4)- β -D-Xyl p residues. • The dissolution of hemicelluloses in different morphological regions was uneven. • The hemicelluloses were dissolved mostly from the secondary cell wall regions. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Eucalyptus was pretreated by tetrahydro-2-furanmethanol/acid aqueous solution. • Cellulose conversion rate was enhanced by 7.3-fold during enzymatic hydrolysis. • The obtained lignin had a high purity (contaminated sugar content 0.6%). • The lignin had a medium molecular weight of 2190 g/mol. Abstract In this study, an organosolv process based on tetrahydro-2-furanmethanol/acid aqueous solution was developed to release lignin and hemicelluloses from eucalyptus for the enhancement of enzymatic hydrolysis. The pretreatment with 80% THFA aqueous solution containing 1% HCl at a solid to liquid ratio of 1:10 was conducted at 120–180 °C for 30 min. Under the serious conditions, the cellulose-rich residue had a high proportion of cellulose up to 87.31%. The enzymatic hydrolysis rate of the cellulose-rich fraction was 94.18%, which was enhanced by 7.3-fold as compared to that of the raw material without pretreatment. The fractionation process resulted in a high delignification rate of 93.95%. The lignin produced with medium molecular weight (2190 g/mol) and high purity (contaminated sugar content 0.6%) was a good substrate for further application as chemicals. [ABSTRACT FROM AUTHOR]

Lignocellulose has been extensively researched over the past decades in response to the growing global significance of renewable resources and environment-friendly materials. Hemicellulose is a large family of polysaccharides present in the primary and secondary cell walls of all land plants, fresh-water plants, and some seaweeds. It has gained significant attention in the development of hemicellulose-based functional polymeric materials owing to its distinct features such as environment-friendliness, renewability, and biodegradability. Recent studies have focused on the isolation, structural characterization, and chemical modification of hemicellulose and the preparation of hemicellulose-based materials. This review, comprehensively elaborates the preparation of hemicellulose-based functional polymeric materials via chemical modification, including the structures and properties of hemicellulose; design strategies for harnessing hemicellulose; and various forms of hemicellulose-based functional polymeric materials such as nanoparticles, films and coatings, hydrogels and aerogels, carbon quantum dots, porous carbons and catalysts. This review provides an update on hemicellulose-based functional materials, with a focus on their controlled-release, adsorption, biosensing, packaging, catalytic conversion, and electrode applications. Future perspectives on challenges and opportunities in the research field of hemicellulose are briefly highlighted. Illustration of chemical modification toward hemicellulose-derived functional polymeric materials. [Display omitted] [ABSTRACT FROM AUTHOR]

In order to explore the contributions of hemicelluloses to the assembly and mechanical properties of cellulose networks, the bacterial cellulose (BC) composites containing xylan and glucomannan were prepared to mimic the polysaccharides network of plant cell walls. Both polysaccharides could induce the change of diameters of cellulose ribbons and influence the crystallization of cellulose. Besides, small-angle X-ray scattering (SAXS) demonstrated that xylan inhibited the assembly of microfibrils into cellulose ribbons, while glucomannan promoted the packing of microfibrils. The changes of cellulose crystalline structure and assembly pattern of cellulose contributed to the lower tensile strength and higher strain at break of the BC composites as compared with the BC. The results provide a profound insight into the structure-property relationships of cellulose networks affected by hemicelluloses, which could be conducive to the development of cellulose biomaterials. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • TMAH could rapidly and massively fractionate hemicelluloses at room temperature. • The hemicellulosic fractionation effect of TMAH was better than that of NaOH. • The yield of hemicelluloses fractionated with TMAH solvent could reach 81.9 %. • TMAH treatment is a feasible and promising method to fractionate hemicelluloses. The fractionation of hemicelluloses is a promising method to improve the comprehensive utilization of lignocellulosic biomass. However, the effective fractionation of hemicelluloses is always limited by the structural complexity and easy degradability. In this study, tetramethylammonium hydroxide (TMAH) was developed to fractionate hemicelluloses from poplar holocellulose with high molecular weights and high yields at room temperature. Approximately 90% of hemicelluloses could be dissolved at room temperature in 1 h, and the yield was up to 81.9%. Compared with the fractionation using NaOH solution, the hemicelluloses isolated by TMAH solvent showed a more complete structure and higher purity. Meanwhile, the retention rate of cellulose after treatment with TMAH was up to 90.2%, and the crystal structure of cellulose in the residues was practically unchanged. Moreover, the TMAH solvent could be recycled to fractionate hemicelluloses. The work provides an elegant and significantly efficient method towards hemicelluloses fractionation and cellulose purification. [ABSTRACT FROM AUTHOR]

To overcome the recalcitrance of lignocellulose structures that hinders the robust bioconversion of biomass for bioethanol and lignin-coproduct productions, efficient approaches are needed to remove hemicelluloses. In this study, a microwave-induced hydrothermal pretreatment of corncob was developed to improve xylo -sugars (xylose, xylooligosaccharides and xylan) yields and to reduce the hemicelluloses loss by controlling NaOH and the severity factor. During this process, the severity factor ranged from 2.30 to 4.30 and the low concentration of NaOH below 0.32% were considered. The results showed that NaOH had a significant impact on xylo -sugars yields as well as the severity factor. The highest xylo -sugars yield of 88.71% was achieved when 0.005% NaOH was employed as the deacetylation agent and the severity factor was 4.00. Meanwhile, the unknown loss of hemicelluloses was limited to 1.51% (based on the total hemicelluloses in corncob) and the formation of furfural was also limited at the low level (1.72%). [ABSTRACT FROM AUTHOR]

Selective dissolution of industrial biowaste is of significant importance for the valorization of biomass. Especially, fractionation of polysaccharides with similar structures is more challenging. Herein, a new kind of cationic hydrotrope, tetraethylammonium hydroxide (TEAH), has been developed for rapid, efficient, and selective dissolution of industrial biowastes-xylan type hemicelluloses from viscose fiber mills. When the concentration of TEAH is 15 wt%, the solubility of industrial crystalline xylan reaches to 13.39 wt% at room temperature. Crystalline or amorphous xylan can be regenerated by adding water or ethanol, with 57.98 % and 95.45 % yields, respectively. Additionally, we showcase hemicelluloses were near-completely extracted from holocellulose without degrading cellulose under ambient temperature by simply adjusting the concentration of TEAH, demonstrating the advantage of the hydrotropic feature. This hydrotrope solvent system features selective, rapid, and room temperature dissolution polysaccharides, which will shed new light in technological applications of the industrial spinning or biorefining processes. We demonstrated a new kind of cationic hydrotrope for rapid, efficient, and selective dissolution of industrial biowaste from viscose fiber mills, crystalline xylan at room temperature. [Display omitted] [ABSTRACT FROM AUTHOR]

This study introduces a facile and green route to fabricate film from bio-based polymers. The film has been prepared by the cross-linking reaction of quaternized hemicelluloses (QH) and chitosan (CHO) with epichlorohydrin (ECH) as crosslinker. It exhibits an excellently mechanical performance as a result of its high tensile strength (up to 37 MPa). Importantly, the roughness of film was 2–5 nm in the area of 400 nm, and smooth surface with pores were presented on the film based on the results of scanning electron microscope (SEM) and atomic force microscope (AFM). Ciprofloxacin was utilized as a mode compound to investigate the loading behavior of the film, and the highest loading concentration was about 18%. The drug release was about 20% in film1 in comparison to only 15% in film3 within 48 h. Furthermore, the results of a 293T cell viability assay indicated its good biocompatibility and non-toxicity. [ABSTRACT FROM AUTHOR]

Bamboo (Phyllostachys pubescens) is a promising high-performance material because of its large planting areas, fast growth, good adaptability, high ultimate strength and stiffness. Hemicelluloses in bamboo have been focused and studied, however, less effort has been dedicated to study on the components, distributions and structures of hemicelluloses in different cells for explaining the mechanism of bamboo growth. Here, we obtained dimethyl sulfoxide (DMSO)-soluble and alkali (NaOH)-soluble hemicelluloses from bamboo fibers (BF) and parenchyma cells (PC), which were separated from bamboo (Phyllostachys pubescens) by their density difference. Molecular weight analysis revealed that the molecular weights of DMSO-soluble and alkali-soluble hemicelluloses isolated from PC were higher than those isolated from BF. Chemical compositions and cell morphology was characterized by field emission scanning electron microscope (FE-SEM), high-performance anion exchange chromatography (HPAEC), and confocal Raman microscope (CRM). The results showed that the content of cellulose (36.32 %) was higher in BF with thicker wall, while the content of lignin and hemicelluloses (36.33 % and 19.39 %, respectively) was higher in PC with thinner wall. The Fourier transform infrared (FT-IR) spectra and nuclear magnetic resonance (NMR) technique analyses indicated that bamboo hemicelluloses were composed of O -acetyl- α - L -arabino-4- O -methylglucurono- β -(1→4)- D -xylan and β -(1→3) (1→4)-glucan. 1H NMR showed that the acetylation degree of H D -Fiber (0.069) was lower than that of H D -Parenchyma (0.127). Particularly, the hemicelluloses isolated from BF were acetylated only on C3 position, while hemicelluloses isolated from PC were acetylated both on C2 and C3 positions. This work presents a novel understanding about hemicelluloses structures of different cell types in bamboo and holds promises for the high-value added utilization of bamboo in the fields of food-related productions and biorefinery. [Display omitted] • Hemicelluloses isolated from bamboo fibers and parenchyma cells were firstly investigated. • Hemicelluloses from parenchyma cells were acetylated on C2 and C3 position. • Hemicelluloses from bamboo fibers were acetylated only on C3 position. • The major structure of hemicelluloses is O -acetyl- α - L -arabino-4- O -methylglucurono-(1→4)- β - D -xylan. • The second major structure of hemicelluloses is β -(1→3) (1→4)-glucan. [ABSTRACT FROM AUTHOR]

In the present study, a graded ethanol precipitation technique was employed to obtain hemicelluloses from the alkali-extracted corncob liquid. The relationship between the structural characteristics of alkali-soluble corncob hemicelluloses and the production of furfural was investigated by a heterogeneous process in a biphasic system. Results showed that alkali-soluble corncob hemicelluloses mainly consisted of glucuronoarabinoxylans and l -arabino-(4- O -methylglucurono)- d -xylans, and the drying way had less influence on the sugar composition, molecular weights and the functional groups of hemicelluloses obtained by the different ethanol concentration precipitation except for the thermal property, the amorphous structure and the ability for the furfural production. Furthermore, alkali-soluble corncob hemicelluloses with higher xylose content, lower branch degree, higher polydispersity and crystallinity contributed to the furfural production. A highest furfural yield of 45.41% with the xylose conversion efficiency of 99.06% and the furfural selectivity of 45.84% was obtained from the oven-dried hemicelluloses precipitated at the 30% (v/v) ethanol concentration. [ABSTRACT FROM AUTHOR]

The hemicelluloses were isolated with 10% KOH at 25 °C from dewaxed and delignified bamboo powder. The alkali-soluble hemicelluloses from Sinocalamus affinis were fractionated by ammonium sulphate precipitation method. The bamboo alkali-soluble hemicelluloses yielded seven hemicellulosic fractions obtained at 0, 5, 15, 25, 40, 55, and 70% saturation with ammonium sulphate. It was found that the more branched hemicelluloses were precipitated at higher ammonium sulphate concentrations (55 and 70%), the more linear hemicelluloses were precipitated at lower ammonium sulphate concentrations (0, 5, 15, 25, and 40%). The molecular weights of hemicellulosic fractions become lower from 35,270 (H 0 ) to 18,680 (H 70 ) g mol −1 with the increasing concentrations of saturated ammonium sulphate from 0 to 70%. Based on the FT-IR, 1 H, 13 C and 2D HSQC NMR studies, the alkali-soluble hemicelluloses were 4- O -methyl-glucuronoarabinoxylans composed of the (1 → 4)-linked β- d -xylopyranosyl backbone with branches at O -3 of α-L-arabinofuranosyl or at O -2 of 4- O -methyl-α- d -glucuronic acid. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cholinium amino acids-based DESs were designed to fractionate hemicellulose. • Integration of water into DESs enhanced hemicellulose removal. • Effect of water in DESs on structural features of hemicellulose were revealed. • DES aqueous mixtures showed reusability in hemicellulose extraction. Novel and green cholinium amino acids-based deep eutectic solvents (DESs) and their aqueous mixtures were synthesized and employed in deconstructing poplar for hemicellulose fractionation. The effects of water content in DESs on hemicellulose dissociation and structural features were comprehensively investigated, along with the reusability of DESs for treatment. The integration of water into DESs could facilitate hemicellulose fractionation, and the cholinium lysine: urea with 5 wt% water (CL: U-5) demonstrated the best performance with a hemicellulose yield of 59.2%. Further structure analysis revealed that hemicelluloses with various branching degrees and molecular weights were obtained with varying water content of DESs. Furthermore, the CL: U-5 had recyclability and reusability with a 40.5% hemicellulose yield obtained after reused three times. The novel and eco-friendly cholinium amino acids-based DESs treatment provides an effective and sustainable strategy for hemicellulose fractionation from woody biomass. [ABSTRACT FROM AUTHOR]

In this study, sweet sorghum stem was subjected to hydrothermal pretreatment (HTP) and alkaline post-treatment to enhance its saccharification ratio by reducing its recalcitrance. The results showed that the HTP (110–210 °C, 0.5–2.0 h) significantly degraded hemicelluloses, and the pretreatment at the temperature higher than 190 °C led to the partial degradation of the cellulose. As compared to the sole HTP, the integrated process removed most of lignin and hemicelluloses, which incurred a higher cellulose saccharification ratio. Under an optimum condition evaluated (HTP at 170 °C for 0.5 h and subsequent 2% NaOH treatment), 77.5% saccharification ratio was achieved, which was 1.8, 2.0 and 5.5 times as compared to the only HTP pretreated substrates, alkaline treated substrates alone and the raw material without pretreatment, respectively. Clearly, the integrated process can be considered as a promising approach to achieve an efficient conversion of lignocellulose to fermentable glucose. [ABSTRACT FROM AUTHOR]

Exploration of lignocellulosic biomass provides a sustainable and eco-friendly route for producing liquid fuels, materials, and chemicals. However, direct utilization of lignocelluloses is limited by the stable and complicated cross-linking structure of the plant cell wall. Hydrothermal pretreatment (HTP) is a green and cost-effective technology because it can disrupt lignin-carbohydrate complex (LCC) linkages, dissolve hemicelluloses and lignin, and redistribute lignin in the cell wall layers without utilization of any chemicals. Thus, HTP is expected to achieve industrial scale in second-generation biorefineries and circular bioeconomies. This review analyzed the deconstruction of lignocelluloses by HTP, with particular emphasis on the formation mechanism of hemicellulose degradation products and the structural evolution of hemicelluloses and lignin accompanying HTP. Meanwhile, the formation mechanism of pseudolignin and its effect on the enzymatic hydrolysis of cellulose as well as strategies for inhibiting lignin recondensation were discussed. • Reviewing the hydrothermal deconstruction of lignocelluloses. • Potential degradation products in hydrolysates are focused. • Formation of pseudolignin and its inhibition on enzymolysis are discussed. • Tracking the structural changes of hemicelluloses and lignin during the treatment. • Strategies to suppress the acid-catalyzed condensation of lignin are summarized. [ABSTRACT FROM AUTHOR]

Acidic deep eutectic solvents (DESs) are promising media for lignin valorization and cellulose conversion due to their good ability in efficient deconstruction of plant cell wall. However, hemicellulose extraction from lignocellulose using acidic DESs remains a challenge. Herein, novel and green Brønsted acidic DESs (BDESs) were synthesized from natural organic acids and common polyols and successively adopted to deconstruct corncob for mild fractionation of hemicelluloses. Oxalic acid (OA)-based BDESs were preferred for corncob processing due to the high solubility of xylan. The results revealed that the suitable acidity of DESs and mild temperature effectively avoided the over-degradation of hemicelluloses. The chemical composition and structural features of the recovered hemicelluloses were investigated systematically. Moreover, after ethylene glycol (EG)-OA BDES was recycled and reused three times, the extraction still resulted in a satisfactory hemicellulose yield. The novel and eco-friendly processing offers a practical and sustainable route for hemicellulose extraction in acidic condition. [Display omitted] • Novel Brønsted acidic deep eutectic solvents (BDESs) were designed and prepared. • BDESs processing facilitated the hemicellulose recovery at mild conditions. • Effects of BDESs on composition and structure of hemicelluloses were revealed. • Ethylene glycol-oxalic acid was reused with a satisfactory hemicellulose yield. [ABSTRACT FROM AUTHOR]

Abstract: The dewaxed sample from Triploid of Populus tomentosa Carr. was extracted by using organic alkaline solvent (Dimethylformamide, DMF) via hydrothermal pretreatment. Neutral sugar compositions and molecular weight analysis demonstrated that the hemicellulosic fractions with a higher Uro/Xyl ratio, namely the more branched hemicelluloses, had higher molecular weights. Interestingly, these results were different from the previous report, in which the ratio of Uro/Xyl in the water-soluble hemicellulosic fraction was more than that of the alkali-soluble hemicellulosic fraction. Spectroscopy (FTIR, 1H NMR, 13C NMR, and HSQC) analysis indicated that the hemicellulosic fractions were mainly composed of (1→4)-linked α-d-glucan from starch and (1→4)-linked β-d-xylan attached with minor amounts of branched sugars from hemicelluloses. In addition, thermal analysis implied that linear hemicelluloses showed more thermal stability than the branched ones during pyrolysis. [Copyright &y& Elsevier]