The purpose of this study was to explore the differences of the hemicelluloses extracted by hydrothermal pretreatment using water and alkaline solutions(Na OH or KOH). The physicochemical properties and structural cha...The purpose of this study was to explore the differences of the hemicelluloses extracted by hydrothermal pretreatment using water and alkaline solutions(Na OH or KOH). The physicochemical properties and structural characteristics of two water-soluble and four alkali-soluble hemicelluloses extracted from the triploid of Populus tomentosa Carr. through the hydrothermal pretreatment were comparatively studied. It was observed that the alkalis(Na OH and KOH) were more effective than distilled water as extractants. Sugar analysis showed that xylose(66.83%~86.49%) was the major constituent, followed by glucose(6.83%~18.49%). Mannose(1.40%~8.42%), galactose(2.17%~4.05%), and arabinose(0.21%~2.26%) were also detected in the hemicellulosic fractions. The results of gelpermeation chromatography(GPC) indicated that the hemicelluloses extracted using the alkaline solutions had relatively higher molecular weights than those solubilized in distilled water. Further, based on spectroscopic ~1Hnuclear magnetic resonance(~1H-NMR) and two-dimensional heteronuclear singular quantum correlation(2D-HSQC) analyses, it was confirmed that the hemicellulosic fractions had a major structure of(1→4)-b-D-xylan and a minor structure of(1→4)-a-D-glucan with small amounts of substituted sugars and glucuronic acid attached.展开更多
Novel superacid SO_4H-functionalized ionic liquids(SFILs) were designed and prepared in this work. The catalytic activities of SFILs were evaluated in xylan hydrolysis and xylose dehydration to produce furfural. Combi...Novel superacid SO_4H-functionalized ionic liquids(SFILs) were designed and prepared in this work. The catalytic activities of SFILs were evaluated in xylan hydrolysis and xylose dehydration to produce furfural. Combined with the results of acid strength of SFILs characterized by solid-state ^(31)P MAS NMR, it was found that the catalytic performance of SFILs was positively correlated to their acid strength. The superacid SFIL [Ch-SO_4H][CF_3SO_3] displayed the best catalytic performance with more than 80% yield of furfural, and it was also obviously superior to usual SO_3H-functionalized acidic ILs, mineral liquid acids, and acidic resin Amberlyst-15 catalysts in catalytic activity under optimized conditions. In addition, the superacid SFIL [Ch-SO_4H][CF_3SO_3] could be easily separated from reaction system and reused at least five times without obvious decrease.展开更多
Hemicellulose in corn straw is a group of complex heteropolysaccharides which are composed of different sugar units, including mannans, xylans, arabinans and galactans. This study developed a simple and practical proc...Hemicellulose in corn straw is a group of complex heteropolysaccharides which are composed of different sugar units, including mannans, xylans, arabinans and galactans. This study developed a simple and practical process for production of 5-hydroxymethyl furfural(HMF) using hemicellulose that was extracted from corn straw. In the hemicellulose degradation process HCOOH/HCOONa was used as buffer solution, and the optimum conditions for maximum HMF yield were explored. Various extraction conditions including NaOH concentration, reaction time,temperature, solid-to-liquid ratio and precipitant were tested for hemicellulose obtaining, giving the optimum condition of 55 °C, 4 h, solid-to-liquid ratio of 1:10, 1.5 mol·L^(-1) NaOH solution and ethanol as precipitant with the yield of 34.16%. Dehydration of hemicellulose under HCOOH/HCOONa buffer solution process, using solution medium of pH = 0.8 hydrolyzed hemicellulose in corn straw at 190 °C after 190 min and 82% of HMF yield was achieved.展开更多
The aim of this study was to investigate the hemicelluloses extracted from Populus tomentosa Carr.by the hydrothermal method with ethanol.The influence of ethanol concentration on the hemicellulosic fractions was syst...The aim of this study was to investigate the hemicelluloses extracted from Populus tomentosa Carr.by the hydrothermal method with ethanol.The influence of ethanol concentration on the hemicellulosic fractions was systematically studied.The chemical compositions and structural features of the hemicellulosic fractions were investigated by a combination of sugar analysis,gel-permeation chromatography,Fourier transform infrared spectroscopy,and one-dimensional proton and carbon-13 nuclear magnetic resonance,and two-dimensional heteronuclear single quantum coherence spectroscopy.Neutral sugar analysis of the hemicellulosic fractions revealed that a higher ethanol concentration(45%~80%) favored the isolation of hemicelluloses with more side chains and lower glucose contents.The molecular weights of these polysaccharides ranged between 2842 g/mol and 5101 g/mol.The results of this study indicate that the hydrothermal ethanol process provides a new pretreatment strategy for the isolation and extraction of biomass.展开更多
Isolation and utilization of hemicellulose are important processes in the pulp mill-based biorefinery. Considering the potential end use of the hemicellulose,this study investigated the concentration of monomeric and ...Isolation and utilization of hemicellulose are important processes in the pulp mill-based biorefinery. Considering the potential end use of the hemicellulose,this study investigated the concentration of monomeric and oligomeric sugars in the hydrolysate derived from autohydrolysis of acacia wood and the obtainment of these sugars via ethanol precipitation. The rate of generation of monomers and oligomers increased dramatically with an increase of the temperature from 160℃ to 180℃. The maximum content of oligomers and total sugars was achieved under conditions of 180℃ and 10 min,170℃ and 85 min,respectively. Interestingly,the maximum yield of hemicellulose via ethanol precipitation was achieved in a much shorter time,compared with the maximum yield of oligomer from the hydrolysate by autohydrolysis. A 6. 66 g / L quantity of hemicellulose was obtained by intensifying the conditions of ethanol precipitation. The hemicellulose characteristics were analyzed by Fourier transform infrared,nuclear magnetic resonance,and ultraviolet spectroscopy,and the molecular weight was determined by gel permeation chromatography and thermal analysis.展开更多
In this study,three kinds of rough-wrought hemicelluloses(RHCs)were obtained via alkali extraction on different raw materials.One was untreated Phyllostachys edulis powder;the second was obtained via benzyl alcohol ex...In this study,three kinds of rough-wrought hemicelluloses(RHCs)were obtained via alkali extraction on different raw materials.One was untreated Phyllostachys edulis powder;the second was obtained via benzyl alcohol extraction of Phyllostachys edulis powder;and the third was holocellulose of Phyllostachys edulis powder.Carboxymethyl hemicelluloses(CMXs)were prepared by the alkalization and etherification of RHCs and were used to enhance the tensile strength of household paper.The results demonstrated a synergistic effect between CMX and polyamide epichlorohydrin resin(PAE),and the addition of small amount of CMX(0.35 kg/t pulp)can significantly improve the dry and wet tensile indices of paper.Study results of CMX strengthening mechanism revealed that the addition of CMX can improve the retention of PAE,especially the fine fiber,due to the adsorption of charges.The use of CMX in paper not only saves production costs but also reduces the proportion of long fiber,which is beneficial to the closed circulation and treatment of white water.展开更多
Hemicellulose is one of the most abundant natural resources, which extensively exist in the pant tissues as the compositions of the cell wall filling between lignin and cellulose. In this review, the hemicellulose bas...Hemicellulose is one of the most abundant natural resources, which extensively exist in the pant tissues as the compositions of the cell wall filling between lignin and cellulose. In this review, the hemicellulose based hydrogels was illustrated in details including the hemicellulose derivatives (such as precursor of hemicellulose based hydrogel), hydrogels fabrication methods, origin of hemicellulose, composite hydrogels, and so on. In addition, the authors as well overviewed the new methods for fabrication of hemicellulose based hydrogels and special functional hemicellulose based hydrogels.展开更多
The emerging food additive, xylo-oligosaccharide(XOSs), was prepared through enzymatic hydrolysis of hemicelluloses isolated from press lye. Two of the three experimental enzyme preparations presented favourable effec...The emerging food additive, xylo-oligosaccharide(XOSs), was prepared through enzymatic hydrolysis of hemicelluloses isolated from press lye. Two of the three experimental enzyme preparations presented favourable effects, while the other one consisting of the nominal enzyme preparations with high enzyme activity was found to have poor catalytic effects. The conversion of xylan exceeded 40% and the selectivity for XOSs reached 90% when the temperature, hemicellulose concentration, dosage of enzymes, and hydrolysis time were 40?C, 100 g/L, 1 ku/g, and 4 h, respectively. Xylo-oligosaccharide preparation through enzymatic hydrolysis of hemicelluloses isolated from press lye was proved to be a feasible process to utilize the by-product of the lye regeneration, which will substantially improve the economy of the lye regeneration and recycling.展开更多
The preparation of xylo-oligosaccharides(XOSs)through hydrolysis of hemicelluloses was studied.The hemicelluloses were isolated from the press lye discharged in the production of viscose,which contained about 30%xylan...The preparation of xylo-oligosaccharides(XOSs)through hydrolysis of hemicelluloses was studied.The hemicelluloses were isolated from the press lye discharged in the production of viscose,which contained about 30%xylan.Then,a factorial experimental design was applied to compare the influences of several factors including the concentrations of sulphuric acid and hemicelluloses,the duration and temperature of the hydrolysis,on the conversion of xylan,and the selectivity for the product–XOSs.The results showed that the hydrolysis duration affects the yield of XOSs to the greatest extent.It is difficult to obtain a high yield of XOSs with sulphuric acid as the hydrolysis catalyst.展开更多
In addition to cellulose and lignin,hemicellulose is an important biomass material.Recently,hemicellulose and its derivatives and materials have attracted increasing attention owing to their unique structures,improved...In addition to cellulose and lignin,hemicellulose is an important biomass material.Recently,hemicellulose and its derivatives and materials have attracted increasing attention owing to their unique structures,improved properties,and promising application potential,and many reports on the extraction,isolation,and modification of hemicellulose are currently available.We summarized the recent developments of hemicellulose and its derivatives and materials by focusing on the extraction,purification,and modification of hemicellulose.The synthesis of hemicellulose-based derivatives and materials was also reviewed.Various methods of extracting,isolating,and modifying hemicellulose were discussed.Remaining challenges related to hemicellulose extraction,purification,and application were mentioned,and directions for further research on hemicellulose were proposed.展开更多
To improve the hydrophobicity of bagasse hemicellulose-based films,glutaraldehyde was applied when preparing films of original and cationic bagasse hemicellulose with the addition of polyvinyl alcohol and sorbitol.The...To improve the hydrophobicity of bagasse hemicellulose-based films,glutaraldehyde was applied when preparing films of original and cationic bagasse hemicellulose with the addition of polyvinyl alcohol and sorbitol.The results showed that the cationic modification could increase the hydrophobicity of the hemicellulose-based film,and the hydrophobicity of hemicellulose-based films crosslinked with glutaraldehyde also increased.However,cationic modification of hemicellulose decreased the stress of the hemicellulose-based film.While crosslinking with glutaraldehyde increased the stress of both the original and cationic hemicellulose-based films.Macrophotography indicated that the film formability of the original hemicellulose was better than that of cationic hemicellulose.Through SEM observation,the degree of bonding of different components of the films was found to be increased due to crosslinking with glutaraldehyde.The crosslinking reaction between glutaraldehyde and hemicellulose was further confirmed by FT-IR spectroscopy.展开更多
Hemicellulose has a wide range of applications,including that as an emulsifier for the food industry and raw material for the synthesis of bioethanol/biochemicals and biodegradable films.Hemicellulose is usually prese...Hemicellulose has a wide range of applications,including that as an emulsifier for the food industry and raw material for the synthesis of bioethanol/biochemicals and biodegradable films.Hemicellulose is usually present as a spent liquor,such as the prehydrolysis liquor of the prehydrolysis kraft dissolving pulp production process and the alkali extraction liquor of the cold caustic extraction of pulp fibers.Due to its dilute nature,hemicellulose needs to be dried for practical utilization,and this is challenging.In this study,cellulose and hemicellulose in a bleached bamboo kraft pulp were separated using an alkali extraction process.Hemicellulose obtained from the extraction liquor was dried by an ammonium carbonate-assisted drying process.The effects of drying time and drying temperature were determined.Structure of the hemicellulose obtained by the ammonium carbonate-assisted drying process was similar to that of original hemicellulose,as revealed by detailed Fourier transform infrared and X-ray diffraction analyses.The novel drying method was more energy efficient and required a shorter drying time than the conventional freeze drying method,and the excellent solubility in alkaline solutions favored the chemical modification of hemicellulose.The dried hemicellulose can be used as a renewable raw material for the preparation of hydrogels and other substances such as bioethanol/biochemicals and biodegradable films.展开更多
Hemicellulose is the second most abundant biomass </span><span style="font-family:Verdana;">in </span><span style="font-family:Verdana;">the world. Because of its unique che...Hemicellulose is the second most abundant biomass </span><span style="font-family:Verdana;">in </span><span style="font-family:Verdana;">the world. Because of its unique chemical structure, hemicellulose has attracted more and more research and industry application under the background of fossil resource shortage and drawbacks. Hem</span><span style="font-family:Verdana;">i</span><span style="font-family:Verdana;">cellulose is ten</span><span style="font-family:Verdana;">ded</span><span style="font-family:Verdana;"> to be modified with esterification, etherification, cross-linkage and so on. These reactions change hemicellulose properties, so that it could be applied in many fields such as medical field, films, hydrogels, conductive polymers. Herein, we reviewed structure, isolation, reaction and applications of hemicellulose. Especially the useful pathways to change the hydrophilic character of hemicelluloses to hydrophobic are reviewed and several applications of these materials are discussed.展开更多
Non-Starch Polysaccahride (NSP) is an agricultural byproduct containing of cellulose, hemicelluloses, and lignin. Hemicellulose has a hydroxyl functional group and carboxylic function on the monomer hemicellulose used...Non-Starch Polysaccahride (NSP) is an agricultural byproduct containing of cellulose, hemicelluloses, and lignin. Hemicellulose has a hydroxyl functional group and carboxylic function on the monomer hemicellulose used as a binding ability for cadmium ion and hence as a pharmaceutical active ingredient to prevent cadmium toxicity. The purpose of this study is to isolate and evaluate hemicelluloses from corn cobs as a binding ability toward cadmium ion. The study is conducted by isolating the corn cobs in such way using 0.2 M NaOH, characterization of hemicellulose from corn cobs produced by Infra Red Spectrofotometry. Binding ability of corn cobs hemicellulose (CCH) was done in 3 ways. The first, it was by titrimetric with cadmium 3 mg/cm3 as a titrant and indicator of 0.05 N NaOH. The second, it was by in vitro test at pH 2 as a comparison to use pectin. The third, the in vivo test was conducted in 3 variations of treatment covering CCH 10 mg, 100 mcg of cadmium for 10 weeks. Assay of cadmium was conducted using atomic absorption spectrophotometry with flame at a wavelength of 228.8 nm. The research result showed that the highest yield of hemicellulose (12.04%) was obtained from delignication with 0.03 M NaOH in 60% ethanol and 3% H2O2, hemicellulose isolation with 500 cm3 of 0.2 M NaOH, and precipitation with 1:4 ratio of 10% acetic acid in 95% ethanol. Characteristics of CCH on infrared vibration methods provide vibrational hemicellulose in the region of 1820-1600 cm-1. It meant that the functional group carbonyl was present, and the vibration widened near 3400-2400 cm-1. It indicated that there was the functional group vibration region of hydroxyl. It also meant that there was carboxylic group and finger print at 1500-500 cm-1. Test results of the titrimetric holding ability showed that CCH was binding 100 mg of cadmium (46.17 ± 0.9256) mg or 46.17%. Binding ability test results at pH 2 showed that 300 mg of CCH yield was binding 30 mg cadmium of (26.68 ± 0.1490) mg or 88.93%. The results of in vivo tests showed that cadmium levels decreased by 95.05%. Based on the exposure, it can be concluded that the CCH isolation yields of 12.04% and can reduce cadmium levels in the blood. It means that the CCH can be used as a chelating agent of cadmium ions by in vitro and in vivo.展开更多
Sulfonated catalysts based on zirconia (SO3</sub>H-ZrO2</sub>), silica (SO3</sub>H-SBA-15) and zeolite (SO3</sub>H-ZSM-5) were studied in the catalytic hydrolysis reaction of hemicellulose in a...Sulfonated catalysts based on zirconia (SO3</sub>H-ZrO2</sub>), silica (SO3</sub>H-SBA-15) and zeolite (SO3</sub>H-ZSM-5) were studied in the catalytic hydrolysis reaction of hemicellulose in a microwave reactor. The prepared catalysts were characterized by various techniques (XRD, N2</sub> physisorption at 77 K, SEM, TEM and NH3</sub>-TPD). The obtained results reveal that despite the differences in their structural and textural properties, the ZrO2</sub>, Al-SBA-15 and H-ZSM-5 supports show similar conversions. Doping supports with sulfonate species created hydrogen bonds between SO3</sub>H groups and increased the amount of weak acid sites, which enhanced the hydrolysis of hemicellulose. SO3</sub>H- ZSM-5 showed the highest catalytic activity followed by SO3</sub>H-SBA-15 while SO3</sub>H-ZrO2</sub> exhibited a poor conversion. Furthermore, the catalytic hydrolysis of the hemicellulose leads to several interesting products, such as formic acid, acetic acid, lactic acid and xylan. The correlation between the catalytic performances and the acidic properties of the different samples indicates that the best catalytic performances were obtained with the least acidic solids and especially when the density of strong acid sites decreases.展开更多
Carboxymethyl chitosan–hemicellulose resin(CMCH) was synthesized by thermal cross-linking process and characterized by FTIR, TGA, and SEM. Subsequently, the adsorption properties of CMCH toward Ni(Ⅱ),Cd(Ⅱ), Cu(Ⅱ),...Carboxymethyl chitosan–hemicellulose resin(CMCH) was synthesized by thermal cross-linking process and characterized by FTIR, TGA, and SEM. Subsequently, the adsorption properties of CMCH toward Ni(Ⅱ),Cd(Ⅱ), Cu(Ⅱ), Hg(Ⅱ), Mn(Ⅶ) and Cr(Ⅵ) were evaluated. Various factors affecting the uptake behavior such as pH, temperature, contact time and the initial concentration of the metal ions were investigated.The results showed that all adsorption processes fit the pseudo-second-order model and Langmuir isotherm equation. Significantly, the regeneration experiments showed CMCH can be used as a potentially recyclable and effective adsorbent for the removal and recovery of metal ions from wastewater.展开更多
Lignocellulosic biomass material sourced from plants and herbaceous sources is considered as a prospective feedstock of inexpensive,potentially carbon-neutral energy.Lignocellulosic biomass is structurally built on ce...Lignocellulosic biomass material sourced from plants and herbaceous sources is considered as a prospective feedstock of inexpensive,potentially carbon-neutral energy.Lignocellulosic biomass is structurally built on cellulose,hemicellulose,and lignin,which are present in varying concentrations based on the feedstock type and play distinct and not well understood mechanical functions in the flow behavior.The frictional characteristics of lignocellulosic biomass particulates influence their flow behavior in biorefineries.Thus,it is important to fundamentally investigate the relative contribution of cellulose,hemicellulose,and lignin to the frictional behavior.However,these three biopolymers are interwoven into a complex matrix in the lignocellulosic biomass,thus making it hard to quantify the contribution of each biopolymer.In this study,we selectively remove hemicellulose from switchgrass and investigate the effects of its diminishing concentration on the coefficient of friction.We observed that the angle of repose and,therefore,the coefficient of friction for a loose assembly of the control and treated switchgrass samples decrease with decreasing hemicellulose content.This indicates the frictional resistance to flow for biomass particulate assemblies is at least proportional to the hemicellulose content.We also established that the observed changes in the frictional behavior were not due to particle morphological characteristics.展开更多
In this study,a hemicellulose recovery process was integrated with a cold caustic extraction(CCE)process in upgrading paper-grade bleached kraft pulp to dissolving grade.Under the conditions of 15%NaOH,10%pulp consist...In this study,a hemicellulose recovery process was integrated with a cold caustic extraction(CCE)process in upgrading paper-grade bleached kraft pulp to dissolving grade.Under the conditions of 15%NaOH,10%pulp consistency,30℃and 1 h,a paper-grade softwood bleached kraft pulp was purified to a dissolving-grade pulp with 97.57%α-cellulose and 1.67%pentosan contents.The spent liquor from the cold caustic extraction process was sequentially extracted with ethanol to precipitate and recover the dissolved hemicelluloses,followed by evaporation to recover the ethanol.After the recovery of hemicelluloses and ethanol,the spent liquor can be reused as the caustic solution for the CCE process without compromising the resulting pulp properties.The results demonstrated that it is feasible to integrate hemicellulose production with the cold caustic extraction process of dissolving pulp production,based on the concept of biorefinery.展开更多
Extraction of hemicelluloses is a primary step in the conversion of plant biomass to valuable biofuels and chemicals.Hemicellulose is distributed in the fiber cell wall,and the compact structure of the fiber cell wall...Extraction of hemicelluloses is a primary step in the conversion of plant biomass to valuable biofuels and chemicals.Hemicellulose is distributed in the fiber cell wall,and the compact structure of the fiber cell wall barricades the transport of hemicelluloses in the extraction process.In this paper we presented a novel microwave-assisted extraction process enhanced with an enzymatic pretreatment to improve the hemicelluloses extraction rate from bagasse.Experimental results showed that the enzyme dosage,alkali concentration and microwave irradiation time were main factors governing the yield of hemicellulose.The optimal conditions of the enzymatic pretreatment were:enzyme dosage of 138 IU/g bagasse and irradiation time of 30 min.Under these conditions,86%of the hemicellulose in bagasse was extracted.After the enzymatic pretreatment the surface area of bagasse increased significantly which facilitated the subsequent microwave-assisted extraction process.展开更多
For the first time,we report an environmentally benign process for the preparation of Pt,Au and Pd NPs at ambient atmospheric pressure in aqueous systems,using water-insoluble alkali lignin(AL)and hemicelluloses as re...For the first time,we report an environmentally benign process for the preparation of Pt,Au and Pd NPs at ambient atmospheric pressure in aqueous systems,using water-insoluble alkali lignin(AL)and hemicelluloses as reducing/protective agents.Both AL and hemicelluloses showed good performances.The solid AL acted as support for metal NPs.The metal particles reduced by hemicelluloses aggregated to larger particles,and the degree of aggregation increased over time.展开更多
基金financial support from the Fundamental Research Funds for the Central Universities(No.JC2013-3,BLYJ201616)Beijing Higher Education Young Elite Teacher Project(No.YETP0763)
文摘The purpose of this study was to explore the differences of the hemicelluloses extracted by hydrothermal pretreatment using water and alkaline solutions(Na OH or KOH). The physicochemical properties and structural characteristics of two water-soluble and four alkali-soluble hemicelluloses extracted from the triploid of Populus tomentosa Carr. through the hydrothermal pretreatment were comparatively studied. It was observed that the alkalis(Na OH and KOH) were more effective than distilled water as extractants. Sugar analysis showed that xylose(66.83%~86.49%) was the major constituent, followed by glucose(6.83%~18.49%). Mannose(1.40%~8.42%), galactose(2.17%~4.05%), and arabinose(0.21%~2.26%) were also detected in the hemicellulosic fractions. The results of gelpermeation chromatography(GPC) indicated that the hemicelluloses extracted using the alkaline solutions had relatively higher molecular weights than those solubilized in distilled water. Further, based on spectroscopic ~1Hnuclear magnetic resonance(~1H-NMR) and two-dimensional heteronuclear singular quantum correlation(2D-HSQC) analyses, it was confirmed that the hemicellulosic fractions had a major structure of(1→4)-b-D-xylan and a minor structure of(1→4)-a-D-glucan with small amounts of substituted sugars and glucuronic acid attached.
基金National Natural Science Foundations of China(Nos.21566011,31570560)the Jiangxi Province Sponsored Programs for Distinguished Young Scholars(No.20162BCB23026)the Science&Technology Programs of Jiangxi Province Department of Education(No.GJJ160272)for financial support
文摘Novel superacid SO_4H-functionalized ionic liquids(SFILs) were designed and prepared in this work. The catalytic activities of SFILs were evaluated in xylan hydrolysis and xylose dehydration to produce furfural. Combined with the results of acid strength of SFILs characterized by solid-state ^(31)P MAS NMR, it was found that the catalytic performance of SFILs was positively correlated to their acid strength. The superacid SFIL [Ch-SO_4H][CF_3SO_3] displayed the best catalytic performance with more than 80% yield of furfural, and it was also obviously superior to usual SO_3H-functionalized acidic ILs, mineral liquid acids, and acidic resin Amberlyst-15 catalysts in catalytic activity under optimized conditions. In addition, the superacid SFIL [Ch-SO_4H][CF_3SO_3] could be easily separated from reaction system and reused at least five times without obvious decrease.
基金Supported by the National Natural Science Foundation of China(No.21576067)
文摘Hemicellulose in corn straw is a group of complex heteropolysaccharides which are composed of different sugar units, including mannans, xylans, arabinans and galactans. This study developed a simple and practical process for production of 5-hydroxymethyl furfural(HMF) using hemicellulose that was extracted from corn straw. In the hemicellulose degradation process HCOOH/HCOONa was used as buffer solution, and the optimum conditions for maximum HMF yield were explored. Various extraction conditions including NaOH concentration, reaction time,temperature, solid-to-liquid ratio and precipitant were tested for hemicellulose obtaining, giving the optimum condition of 55 °C, 4 h, solid-to-liquid ratio of 1:10, 1.5 mol·L^(-1) NaOH solution and ethanol as precipitant with the yield of 34.16%. Dehydration of hemicellulose under HCOOH/HCOONa buffer solution process, using solution medium of pH = 0.8 hydrolyzed hemicellulose in corn straw at 190 °C after 190 min and 82% of HMF yield was achieved.
基金Financial support from the Foundation(No.KF201607)of the Key Laboratory of Pulp and Paper Science and Technology of the Ministry of Education/Shandong Province of China
文摘The aim of this study was to investigate the hemicelluloses extracted from Populus tomentosa Carr.by the hydrothermal method with ethanol.The influence of ethanol concentration on the hemicellulosic fractions was systematically studied.The chemical compositions and structural features of the hemicellulosic fractions were investigated by a combination of sugar analysis,gel-permeation chromatography,Fourier transform infrared spectroscopy,and one-dimensional proton and carbon-13 nuclear magnetic resonance,and two-dimensional heteronuclear single quantum coherence spectroscopy.Neutral sugar analysis of the hemicellulosic fractions revealed that a higher ethanol concentration(45%~80%) favored the isolation of hemicelluloses with more side chains and lower glucose contents.The molecular weights of these polysaccharides ranged between 2842 g/mol and 5101 g/mol.The results of this study indicate that the hydrothermal ethanol process provides a new pretreatment strategy for the isolation and extraction of biomass.
基金supported by the National Natural Science Foundation of China(31470603)the Natural Science Foundation of Liaoning Province(2015020592)+1 种基金the Liaoning BaiQ ian Wan Talents Program(20149210-64)the Open Fund of State Key Lab of Pulp and Paper Engineering of China(201449)
文摘Isolation and utilization of hemicellulose are important processes in the pulp mill-based biorefinery. Considering the potential end use of the hemicellulose,this study investigated the concentration of monomeric and oligomeric sugars in the hydrolysate derived from autohydrolysis of acacia wood and the obtainment of these sugars via ethanol precipitation. The rate of generation of monomers and oligomers increased dramatically with an increase of the temperature from 160℃ to 180℃. The maximum content of oligomers and total sugars was achieved under conditions of 180℃ and 10 min,170℃ and 85 min,respectively. Interestingly,the maximum yield of hemicellulose via ethanol precipitation was achieved in a much shorter time,compared with the maximum yield of oligomer from the hydrolysate by autohydrolysis. A 6. 66 g / L quantity of hemicellulose was obtained by intensifying the conditions of ethanol precipitation. The hemicellulose characteristics were analyzed by Fourier transform infrared,nuclear magnetic resonance,and ultraviolet spectroscopy,and the molecular weight was determined by gel permeation chromatography and thermal analysis.
基金financially supported by the National Key R&D Program China(No.2017YFB0307901).
文摘In this study,three kinds of rough-wrought hemicelluloses(RHCs)were obtained via alkali extraction on different raw materials.One was untreated Phyllostachys edulis powder;the second was obtained via benzyl alcohol extraction of Phyllostachys edulis powder;and the third was holocellulose of Phyllostachys edulis powder.Carboxymethyl hemicelluloses(CMXs)were prepared by the alkalization and etherification of RHCs and were used to enhance the tensile strength of household paper.The results demonstrated a synergistic effect between CMX and polyamide epichlorohydrin resin(PAE),and the addition of small amount of CMX(0.35 kg/t pulp)can significantly improve the dry and wet tensile indices of paper.Study results of CMX strengthening mechanism revealed that the addition of CMX can improve the retention of PAE,especially the fine fiber,due to the adsorption of charges.The use of CMX in paper not only saves production costs but also reduces the proportion of long fiber,which is beneficial to the closed circulation and treatment of white water.
文摘Hemicellulose is one of the most abundant natural resources, which extensively exist in the pant tissues as the compositions of the cell wall filling between lignin and cellulose. In this review, the hemicellulose based hydrogels was illustrated in details including the hemicellulose derivatives (such as precursor of hemicellulose based hydrogel), hydrogels fabrication methods, origin of hemicellulose, composite hydrogels, and so on. In addition, the authors as well overviewed the new methods for fabrication of hemicellulose based hydrogels and special functional hemicellulose based hydrogels.
基金Supported by Science and Education Integration Program of Henan University of Technology
文摘The emerging food additive, xylo-oligosaccharide(XOSs), was prepared through enzymatic hydrolysis of hemicelluloses isolated from press lye. Two of the three experimental enzyme preparations presented favourable effects, while the other one consisting of the nominal enzyme preparations with high enzyme activity was found to have poor catalytic effects. The conversion of xylan exceeded 40% and the selectivity for XOSs reached 90% when the temperature, hemicellulose concentration, dosage of enzymes, and hydrolysis time were 40?C, 100 g/L, 1 ku/g, and 4 h, respectively. Xylo-oligosaccharide preparation through enzymatic hydrolysis of hemicelluloses isolated from press lye was proved to be a feasible process to utilize the by-product of the lye regeneration, which will substantially improve the economy of the lye regeneration and recycling.
基金finically supported by Science and Education Integration Program of Henan University of Technology
文摘The preparation of xylo-oligosaccharides(XOSs)through hydrolysis of hemicelluloses was studied.The hemicelluloses were isolated from the press lye discharged in the production of viscose,which contained about 30%xylan.Then,a factorial experimental design was applied to compare the influences of several factors including the concentrations of sulphuric acid and hemicelluloses,the duration and temperature of the hydrolysis,on the conversion of xylan,and the selectivity for the product–XOSs.The results showed that the hydrolysis duration affects the yield of XOSs to the greatest extent.It is difficult to obtain a high yield of XOSs with sulphuric acid as the hydrolysis catalyst.
基金This work was financially supported by the National Key R&D Program of China(2019YFC1905901).
文摘In addition to cellulose and lignin,hemicellulose is an important biomass material.Recently,hemicellulose and its derivatives and materials have attracted increasing attention owing to their unique structures,improved properties,and promising application potential,and many reports on the extraction,isolation,and modification of hemicellulose are currently available.We summarized the recent developments of hemicellulose and its derivatives and materials by focusing on the extraction,purification,and modification of hemicellulose.The synthesis of hemicellulose-based derivatives and materials was also reviewed.Various methods of extracting,isolating,and modifying hemicellulose were discussed.Remaining challenges related to hemicellulose extraction,purification,and application were mentioned,and directions for further research on hemicellulose were proposed.
文摘To improve the hydrophobicity of bagasse hemicellulose-based films,glutaraldehyde was applied when preparing films of original and cationic bagasse hemicellulose with the addition of polyvinyl alcohol and sorbitol.The results showed that the cationic modification could increase the hydrophobicity of the hemicellulose-based film,and the hydrophobicity of hemicellulose-based films crosslinked with glutaraldehyde also increased.However,cationic modification of hemicellulose decreased the stress of the hemicellulose-based film.While crosslinking with glutaraldehyde increased the stress of both the original and cationic hemicellulose-based films.Macrophotography indicated that the film formability of the original hemicellulose was better than that of cationic hemicellulose.Through SEM observation,the degree of bonding of different components of the films was found to be increased due to crosslinking with glutaraldehyde.The crosslinking reaction between glutaraldehyde and hemicellulose was further confirmed by FT-IR spectroscopy.
基金the National Key Research and Development Program of China(2017YFB0307900,2019YFC1905903)the National Natural Science Foundation of China(31700507)the Major Project on the Integration of Industry-Education-Research of Fujian Provincial Department of Science and Technology(2018H6003).
文摘Hemicellulose has a wide range of applications,including that as an emulsifier for the food industry and raw material for the synthesis of bioethanol/biochemicals and biodegradable films.Hemicellulose is usually present as a spent liquor,such as the prehydrolysis liquor of the prehydrolysis kraft dissolving pulp production process and the alkali extraction liquor of the cold caustic extraction of pulp fibers.Due to its dilute nature,hemicellulose needs to be dried for practical utilization,and this is challenging.In this study,cellulose and hemicellulose in a bleached bamboo kraft pulp were separated using an alkali extraction process.Hemicellulose obtained from the extraction liquor was dried by an ammonium carbonate-assisted drying process.The effects of drying time and drying temperature were determined.Structure of the hemicellulose obtained by the ammonium carbonate-assisted drying process was similar to that of original hemicellulose,as revealed by detailed Fourier transform infrared and X-ray diffraction analyses.The novel drying method was more energy efficient and required a shorter drying time than the conventional freeze drying method,and the excellent solubility in alkaline solutions favored the chemical modification of hemicellulose.The dried hemicellulose can be used as a renewable raw material for the preparation of hydrogels and other substances such as bioethanol/biochemicals and biodegradable films.
文摘Hemicellulose is the second most abundant biomass </span><span style="font-family:Verdana;">in </span><span style="font-family:Verdana;">the world. Because of its unique chemical structure, hemicellulose has attracted more and more research and industry application under the background of fossil resource shortage and drawbacks. Hem</span><span style="font-family:Verdana;">i</span><span style="font-family:Verdana;">cellulose is ten</span><span style="font-family:Verdana;">ded</span><span style="font-family:Verdana;"> to be modified with esterification, etherification, cross-linkage and so on. These reactions change hemicellulose properties, so that it could be applied in many fields such as medical field, films, hydrogels, conductive polymers. Herein, we reviewed structure, isolation, reaction and applications of hemicellulose. Especially the useful pathways to change the hydrophilic character of hemicelluloses to hydrophobic are reviewed and several applications of these materials are discussed.
文摘Non-Starch Polysaccahride (NSP) is an agricultural byproduct containing of cellulose, hemicelluloses, and lignin. Hemicellulose has a hydroxyl functional group and carboxylic function on the monomer hemicellulose used as a binding ability for cadmium ion and hence as a pharmaceutical active ingredient to prevent cadmium toxicity. The purpose of this study is to isolate and evaluate hemicelluloses from corn cobs as a binding ability toward cadmium ion. The study is conducted by isolating the corn cobs in such way using 0.2 M NaOH, characterization of hemicellulose from corn cobs produced by Infra Red Spectrofotometry. Binding ability of corn cobs hemicellulose (CCH) was done in 3 ways. The first, it was by titrimetric with cadmium 3 mg/cm3 as a titrant and indicator of 0.05 N NaOH. The second, it was by in vitro test at pH 2 as a comparison to use pectin. The third, the in vivo test was conducted in 3 variations of treatment covering CCH 10 mg, 100 mcg of cadmium for 10 weeks. Assay of cadmium was conducted using atomic absorption spectrophotometry with flame at a wavelength of 228.8 nm. The research result showed that the highest yield of hemicellulose (12.04%) was obtained from delignication with 0.03 M NaOH in 60% ethanol and 3% H2O2, hemicellulose isolation with 500 cm3 of 0.2 M NaOH, and precipitation with 1:4 ratio of 10% acetic acid in 95% ethanol. Characteristics of CCH on infrared vibration methods provide vibrational hemicellulose in the region of 1820-1600 cm-1. It meant that the functional group carbonyl was present, and the vibration widened near 3400-2400 cm-1. It indicated that there was the functional group vibration region of hydroxyl. It also meant that there was carboxylic group and finger print at 1500-500 cm-1. Test results of the titrimetric holding ability showed that CCH was binding 100 mg of cadmium (46.17 ± 0.9256) mg or 46.17%. Binding ability test results at pH 2 showed that 300 mg of CCH yield was binding 30 mg cadmium of (26.68 ± 0.1490) mg or 88.93%. The results of in vivo tests showed that cadmium levels decreased by 95.05%. Based on the exposure, it can be concluded that the CCH isolation yields of 12.04% and can reduce cadmium levels in the blood. It means that the CCH can be used as a chelating agent of cadmium ions by in vitro and in vivo.
文摘Sulfonated catalysts based on zirconia (SO3</sub>H-ZrO2</sub>), silica (SO3</sub>H-SBA-15) and zeolite (SO3</sub>H-ZSM-5) were studied in the catalytic hydrolysis reaction of hemicellulose in a microwave reactor. The prepared catalysts were characterized by various techniques (XRD, N2</sub> physisorption at 77 K, SEM, TEM and NH3</sub>-TPD). The obtained results reveal that despite the differences in their structural and textural properties, the ZrO2</sub>, Al-SBA-15 and H-ZSM-5 supports show similar conversions. Doping supports with sulfonate species created hydrogen bonds between SO3</sub>H groups and increased the amount of weak acid sites, which enhanced the hydrolysis of hemicellulose. SO3</sub>H- ZSM-5 showed the highest catalytic activity followed by SO3</sub>H-SBA-15 while SO3</sub>H-ZrO2</sub> exhibited a poor conversion. Furthermore, the catalytic hydrolysis of the hemicellulose leads to several interesting products, such as formic acid, acetic acid, lactic acid and xylan. The correlation between the catalytic performances and the acidic properties of the different samples indicates that the best catalytic performances were obtained with the least acidic solids and especially when the density of strong acid sites decreases.
基金supported by the National Natural Science Foundation of China(No.21403091)the Natural Science Foundation of Jiangsu Province,China(No.BK20130486)+2 种基金Jiangsu Planned Projects for Postdoctoral Research Funds(No.1601066B)a Project Funded by Jiangsu University for Senior Intellectuals(Nos14JDG128 and 12JDG093)supporting this project under the innovation/entrepreneurship program (Surencaiban[2015]26).
文摘Carboxymethyl chitosan–hemicellulose resin(CMCH) was synthesized by thermal cross-linking process and characterized by FTIR, TGA, and SEM. Subsequently, the adsorption properties of CMCH toward Ni(Ⅱ),Cd(Ⅱ), Cu(Ⅱ), Hg(Ⅱ), Mn(Ⅶ) and Cr(Ⅵ) were evaluated. Various factors affecting the uptake behavior such as pH, temperature, contact time and the initial concentration of the metal ions were investigated.The results showed that all adsorption processes fit the pseudo-second-order model and Langmuir isotherm equation. Significantly, the regeneration experiments showed CMCH can be used as a potentially recyclable and effective adsorbent for the removal and recovery of metal ions from wastewater.
基金The authors would like to acknowledge funding support for this research by UTIA AgResearch through AgResearch Tuition Program.
文摘Lignocellulosic biomass material sourced from plants and herbaceous sources is considered as a prospective feedstock of inexpensive,potentially carbon-neutral energy.Lignocellulosic biomass is structurally built on cellulose,hemicellulose,and lignin,which are present in varying concentrations based on the feedstock type and play distinct and not well understood mechanical functions in the flow behavior.The frictional characteristics of lignocellulosic biomass particulates influence their flow behavior in biorefineries.Thus,it is important to fundamentally investigate the relative contribution of cellulose,hemicellulose,and lignin to the frictional behavior.However,these three biopolymers are interwoven into a complex matrix in the lignocellulosic biomass,thus making it hard to quantify the contribution of each biopolymer.In this study,we selectively remove hemicellulose from switchgrass and investigate the effects of its diminishing concentration on the coefficient of friction.We observed that the angle of repose and,therefore,the coefficient of friction for a loose assembly of the control and treated switchgrass samples decrease with decreasing hemicellulose content.This indicates the frictional resistance to flow for biomass particulate assemblies is at least proportional to the hemicellulose content.We also established that the observed changes in the frictional behavior were not due to particle morphological characteristics.
文摘In this study,a hemicellulose recovery process was integrated with a cold caustic extraction(CCE)process in upgrading paper-grade bleached kraft pulp to dissolving grade.Under the conditions of 15%NaOH,10%pulp consistency,30℃and 1 h,a paper-grade softwood bleached kraft pulp was purified to a dissolving-grade pulp with 97.57%α-cellulose and 1.67%pentosan contents.The spent liquor from the cold caustic extraction process was sequentially extracted with ethanol to precipitate and recover the dissolved hemicelluloses,followed by evaporation to recover the ethanol.After the recovery of hemicelluloses and ethanol,the spent liquor can be reused as the caustic solution for the CCE process without compromising the resulting pulp properties.The results demonstrated that it is feasible to integrate hemicellulose production with the cold caustic extraction process of dissolving pulp production,based on the concept of biorefinery.
基金supported by the National Natural Science Foundation of China (Grant No.31460176,21466017)the Opening Project of Guangxi Key Laboratory of Clean Pulp&Papermaking and Pollution Control (Grant No.ZR201606).
文摘Extraction of hemicelluloses is a primary step in the conversion of plant biomass to valuable biofuels and chemicals.Hemicellulose is distributed in the fiber cell wall,and the compact structure of the fiber cell wall barricades the transport of hemicelluloses in the extraction process.In this paper we presented a novel microwave-assisted extraction process enhanced with an enzymatic pretreatment to improve the hemicelluloses extraction rate from bagasse.Experimental results showed that the enzyme dosage,alkali concentration and microwave irradiation time were main factors governing the yield of hemicellulose.The optimal conditions of the enzymatic pretreatment were:enzyme dosage of 138 IU/g bagasse and irradiation time of 30 min.Under these conditions,86%of the hemicellulose in bagasse was extracted.After the enzymatic pretreatment the surface area of bagasse increased significantly which facilitated the subsequent microwave-assisted extraction process.
基金supported by the National Program on Key Basic Research Project (973Program,No.2011CB933700)the National Natural Science Foundation of China (51172247,51043003,50773086)Hebei Key Discipline Construction Project.
文摘For the first time,we report an environmentally benign process for the preparation of Pt,Au and Pd NPs at ambient atmospheric pressure in aqueous systems,using water-insoluble alkali lignin(AL)and hemicelluloses as reducing/protective agents.Both AL and hemicelluloses showed good performances.The solid AL acted as support for metal NPs.The metal particles reduced by hemicelluloses aggregated to larger particles,and the degree of aggregation increased over time.
