Separation Of Hemicellulose Research Articles

A novel process for obtaining high quality cellulose acetate from green landscaping waste

As a typical lignocellulosic biomass, abundant amount of green landscaping waste can be used as low-cost feedstock to produce value-added chemicals. This work developed a novel process to obtain industrially important cellulose acetate from green landscaping waste after separation of hemicellulose as a substrate rich in monomeric xylose. Sixteen samples of selected green waste were pretreated with diluted acid at moderate temperatures. Afterwards, the residues were treated with acetic anhydride and a small amount of sulfuric acid as catalyst to make cellulose acetate. The quantity and quality of cellulose acetate were analyzed by Fourier Transform Infrared Spectroscopy (FT-IR), Nuclear Magnetic Resonance (1H NMR), and Gel Chromatography (GPC). The activation mechanisms of the diluted-phosphoric-acid pretreatment on yields and quality of cellulose acetate were also investigated using Thermogravimetric Analyzer (TGA) and Scanning Electron Microscope (SEM). Without the pretreatment, the yields of cellulose acetate from green landscaping waste ranged from 4.0% to 8.6%. After the pretreatment the mean yield of cellulose acetate from all sixteen green waste significantly increased to approximately 35%, illustrating the high efficiency and wide applicability of our proposed method.

Integrated microwave and alkaline treatment for the separation between hemicelluloses and cellulose from cellulosic fibers

In this study, the microwave was employed during the alkaline treatment process, in order to separate the hemicelluloses and cellulose from a delignified hardwood kraft pulp. In relation to hemicelluloses yield, the integrated microwave and alkaline treatment resulted in 9.25% and 12.05% at 50°C and 80°C, respectively. Correspondingly, the resultant pulp fibers presented the increased cellulose content, which was desirable for manufacturing dissolving pulp. Additionally, the effect from mechanical refining pretreatment followed microwave and alkaline treatment, on the separation of hemicelluloses and cellulose, was also investigated.

Hemicelluloses separation from caustic-containing process stream by ultrafiltration

ABSTRACTThe present work aimed to study the performance of ultrafiltration (UF) membranes for hemicelluloses separation, from a caustic-containing highly alkaline, cellulose purification solvent stream of viscose rayon production process, and to understand the membrane behaviour, effect of multiple use cycle, identify potential performance drawbacks and propose possible solutions. Screening experiments showed that an UF membrane with a nominal molecular weight cut-off value of 3 kDa can be used to separate hemicelluloses from alkaline process stream. UF membrane was found to be prone to performance deterioration with time due to fouling. Higher feed temperature helped in improving the membrane flux values while maintaining hemicelluloses retention.

Kinetics and thermodynamic parameters of ionic liquid pretreated rubber wood biomass

The impact of ionic liquids (ILs) namely 1-butyl-3-methylimidazolium chloride ([BMim][Cl]) and 1-butyl-3-methylimidazolium acetate ([BMIM][OAc]) on rubber wood pyrolysis kinetic and thermodynamic parameters were investigated using thermogravimetric analysis (TGA). The ILs treated and untreated samples were characterized with FT-IR and elemental (CHNS) analyses. The activation energy for untreated and ILs treated rubber wood (RW) were determined using the Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Starink methods. The average activation energy calculated using FWO, KAS and Starink methods for untreated rubber wood was 120.15kJ/mol, 117.10kJ/mol and 117.60kJ/mol, [BMIM][Cl] treated rubber wood was 87.32kJ/mol, 77.73kJ/mol, and 81.16kJ/mol, while [BMIM][OAc] treated rubber wood was 85.64kJ/mol, 76.63kJ/mol, and 80.47kJ/mol, respectively. Starink method was further used to determine the pre-exponential factor and thermodynamic parameters of untreated and ILs treated samples. The thermo kinetics and thermodynamic parameters indicate that ILs pre-treatment decreases the thermal stability of the rubber wood. From FTIR analysis, it was observed that ILs pre-treatment affected the chemical composition of rubber wood. Elemental analysis showed that ILs treated RW has a higher content of Hydrogen/Carbon ratio because of the separation of lignin and hemicellulose during pre-treatment. It was concluded that ILs pre-treatment provided a potential way to improve the thermal conversion efficiency of rubber wood.

Application of ionic liquids for effective use of woody biomass

Ionic liquids are salts that have melting points around ambient temperature and unique characteristics, such as high solubility, extremely low volatility, incombustibility and low viscosity. Application of ionic liquids in wood processing technology has attracted attention and is expected to promote further use of wood. They are effective as wood-preserving agents to enhance decay-resistance and also improve fire resistance of wood. Ionic liquids have been used as reaction solvents for preparing various cellulose derivatives or composites with other materials. Attempts have been made to use ionic liquids in pretreatments for enzymatic hydrolysis when producing bio-ethanol from cellulose or wood. Ionic liquids also have been shown to be effective for dissolution of cellulose or wood, forming the basis for studies into the separation of cellulose, hemicellulose and lignin from wood. The effective separation of these components is essential for chemical use of wood, and ionic liquid treatment thus has potential as an enabling technique in biorefineries. Moreover, ionic liquids induce depolymerization of solubilized wood polymers, which may be applicable to the production of useful chemicals from wood polymers such as cellulose, hemicellulose and lignin.

Сравнение площади поверхности сухого и влажного лигноцеллюлозного сырья до и после предобработки

Obtaining valuable components of fuels and petrochemical products from vegetable raw materials is complicated by its complex structure. To reduce energy consumption and increase the yield of desired products biomass pretreatment is used, during which partial removal of lignin and hemicellulose takes place. The use of irradiation causes destruction of intermolecular and intramolecular bonds within the structure of the lignocellulosic materials, which leads to decrease in the degree of crystallinity and increase of available surface area. Pretreatment with ionic liquids facilitates separation of lignin and hemicellulose from cellulose which dissolves and acquires amorphous structure. The resulting substrate has high available surface area, but it loses quality upon drying. Determination of the degree of crystallinity by X-ray diffraction and the available surface area and pore size by the adsorption method using an indicator of the effectiveness of the pretreatment is conducted. The use of gas adsorption methods requires drying the samples, which negates the results of many kinds of preprocessing. The use of liquid-phase adsorption methods based on the comparison of the concentration of substances in the feed solution, and after equilibrium with the surface of the substrate are established, can more accurately determine the available surface area and pores size. Application of liquid phase method does not require any preparation of samples prior to analysis, in contrast to the gas adsorption method. When comparing the results of analysis by gas adsorption BET of liquid phase adsorption of glucose on the surface of the samples of the lignocellulosic raw material it has been found that after ionic liquids pretreatment available surface area has increased by 300-400 %, and the pore volume increased by 450-1700 %.

Oxygen Enhances Polyoxometalate-based Catalytic Dissolution and Delignification of Woody Biomass in Ionic Liquids

Complete dissolution and over 90% delignification of Southern yellow pine (<0.125 mm) can be achieved in the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) at 110 °C for 6 h by the catalytic action of polyoxometalate in the presence of an appropriate O2 feed. Cellulose-rich materials (CRMs), or pulps, and hemicellulose with a limited lignin content and free lignin were subsequently recovered by adding antisolvents to the IL solution, followed by filtration. Comparison of wood processing in [C2mim][OAc]/POM with or without O2 revealed that the presence of oxygen can greatly facilitate the dissolution, delignification, separation of hemicellulose, and oxidation of lignin. The main products from lignin oxidation were extracted from the IL using benzene and then tetrahydrofuran, and were shown by gas chromatography−mass spectrometry (GC–MS) to be methyl vanillate, acetovanillone, vanillic acid, methyl 3-(3-methoxy-4-hydroxyphenyl) propionate, and methyl 4-hydroxybenzoate. This study suggests that treating wood with a [C2mim][OAc]/POM/O2 system could be a viable strategy to separate wood components with high efficiency and obtain cellulose with high purity for materials or biorefinery applications, particularly those that desire smaller lignin oxidation fragments for further processing.

Ethanol and lignin production from Brazilian empty fruit bunch biomass

Brazil Government is promoting palm plantations to use degraded land for biofuels. Palm production is expected to increase 35 per cent in future and there would be profuse biomass available that needs to be handled efficiently. Therefore, in this study the potential of EFB from Brazil as raw material for biorefinery was explored by compositional analysis and pretreatment conditions optimization to produce ethanol and co-products. EFB from Brazil contains significant cellulose, hemicellulose, lignin and low ash content. The optimized dilute sulfuric acid pretreatment conditions for efficient cellulose and hemicellulose separation were 160°C temperature, 1.025% v/v acid concentration, 10.5min and 20% solid loading. Under optimum pretreatment process conditions, low enzyme loading (10FPU, 20IU cellulase and glucosidase enzyme/g glucan) and 15% solid loading, 51.1g ethanol, 344.1g solid residue (65% lignin and 24.87MJ/kg LHV) and 3.7l xylose rich liquid could be produced per kg dry EFB.

Combination of Low-pressure Steam Explosion and Alkaline Peroxide Pretreatment for Separation of Hemicellulose

Low-pressure steam explosion (LPSE) combined with alkaline peroxide (AP) pretreatment was first employed to separate hemicellulose from Lespedeza stalks. The monosaccharide composition and molecular weight distribution of the obtained hemicellulose fractions were characterized in this study. The results show that the hemicellulose extracted from Lespedeza stalks consisted of xylose, glucose, galactose, and mannose, which was a mixture of arabinoxylans and xyloglucans or β-glucans. The yield of hemicellulose fractions after AP pretreatment ranged from 11.2% (2.5% hydrogen peroxide (H2O2), w/v for 12 h) to 12.2% (3.3% H2O2, w/v for 72 h). The molecular weight of hemicellulose decreased from 2,458 g/mol to 1,984 g/mol after AP pretreatment, indicating its degradation reaction. The structure of hemicellulose was analyzed by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, and heteronuclear single quantum coherence. The AP pretreatment partially cleaved the backbone and the ether linkage between lignin and hemicelluloses. Also, branched-chain α-D-arabinofuranosyl in which β-D-xylose substituted at the C-3 position (monosubstituted) was removed, illustrating a partial debranching reaction. Therefore, the combination of low-pressure steam explosion and alkaline peroxide pretreatment (LPSE-AP) is an effective pretreatment method to separate hemicellulose from Lespedeza stalk.

Separation of Hemicellulose and Cellulose from Wood Pulp by Means of Ionic Liquid/Cosolvent Systems

Pulp of high cellulose content, also known as dissolving pulp, is needed for many purposes, including the production of cellulosic fibers and films. Paper-grade pulp, which is rich in hemicellulose, could be a cheap source but must be refined. Hitherto, hemicellulose extraction procedures suffered from a loss of cellulose and the non-recoverability of unaltered hemicelluloses. Herein, an environmentally benign fractionation concept is presented, using mixtures of a cosolvent (water, ethanol, or acetone) and the cellulose dissolving ionic liquid 1-ethyl-3-methylimidazolium acetate (EMIM OAc). This cosolvent addition was monitored using Kamlet-Taft parameters, and appropriate stirring conditions (3 h at 60 °C) were maintained. This allowed the fractionation of a paper-grade kraft pulp into a separated cellulose and a regenerated hemicellulose fraction. Both of these exhibited high levels of purity, without any yield losses or depolymerization. Thus, this process represents an ecologically and economically efficient alternative in producing dissolving pulp of highest purity.

Hemicelluloses Separation from APMP Liquid

On the premise of biomass comprehensive using concept, the screw section liquid of aspen APMP was treated by alcohol precipitation method to separate and analyze the hemicelluloses. In the traditional alcohol separation system, not only the effect of the temperature, alcohol dosage, pH value and precipitation time on the hemicelluloses separation was researched, but also the methanol system and alcohol-CPAM system were discussed. The results showed that the hemicelluloses yield was relatively ideal when the AMPM liquid was treated by 2.5 times volume of alcohol at pH of 4.0 at 45°C for 30 min. In addition, compared with alcohol system, the methanol dosage was decreased by about 12% in methanol system and the alcohol dosage was also decreased In the alcohol-CPAM system, when the hemicelluloses yield was similar.

A possible means of realizing a sacrifice-free three component separation of lignocellulose from wood biomass using an amino acid ionic liquid

Lignocellulose materials are potentially valuable resources for transformation into many bio-products. However, because of the difficulty in fractionating them into cellulose, hemicellulose, and lignin by a simple method directly from wood biomass, their economical conversion into high value-added products has been greatly limited. We found that N-methyl-N-(2-methoxyethyl)pyrolidin-1-ium 2,6-diaminohexanoate ([P1ME][Lys]) dissolved lignin very well below 60 °C, but that 80 °C was required for it to dissolve cellulose. Taking advantage of this difference in dissolution ability, direct extraction of lignin from wood biomass has been accomplished under mild conditions without the use of any hazardous reagents. Since lignin acts as the essential glue that binds cellulose and hemicellulose and gives plants their structural integrity, we have achieved the demonstration of the sacrifice-free separation of cellulose, hemicellulose, and lignin from wood biomass (Japanese cedar: Cryptomeria japonica).

Comparison of Different Pre-treatment Methods for Separating Hemicellulose from Straw During Lignocellulose Bioethanol Production

The interest in the development of methods to reduce greenhouse gases has increased enormously. Therefore, one focus is on the production of biofuels like advanced generation bioethanol from lignocellulosic agricultural residues such as wheat straw. The main focus of this work is the specific separation of hemicellulose into soluble xylose and its oligomers from pre-treated wheat straw in order to generate an additional carbon source for microorganisms. Wheat straw was pre-treated by either steam explosion, acid or alkaline pre-treatment and the amounts of xylose that were generated were compared. The best method for hemicellulose separation was the acid pre-treatment.

Search for optimum conditions of wheat straw hemicelluloses cold alkaline extraction process

A method for the selective extraction of hemicellulose from wheat straw involving cold alkaline extraction and subsequent separation by precipitation with ethanol is proposed. Wheat straw affords selective separation of the hemicellulose fraction from the cellulose and lignin fractions with the proposed method. The hemicellulose yield was optimized by using a 2n factor design to examine the influence of temperatures (temperature was designed between 20 and 40°C), operation times (operation time was designed between 30 and 60min) and alkali concentrations (alkali concentration was designed between 80 and 120gL−1). These conditions allowed 56.1% of all hemicellulose initially present in the raw material, and 59.1% of the lignin, to be extracted. Subsequent separation of hemicellulose in the liquid phase from the cold alkaline extraction by precipitation with ethanol provided a fraction containing 39.4% of all hemicellulose (45.2% hemicellulose in extract/total extract) and only 12% of all lignin in the raw material.

Hemicelluloses Separation from Black Liquor

The black liquor from NaOH-AQ pulping of bagasse was treated by conventional alcohol precipitation method to separate hemicelluloses. In the system of alcohol/methanol, some parameters which may affect the hemicelluloses precipitation were discussed, such as mixed alcohols charge, temperature, pH and time. The obtained hemicelluloses were analyzed by FT-IR. The results showed that compared with conventional separation system of hemicelluloses by alcohol, when the Valcohol : Vmethanol was 5:5 and pH was 4.5 at 45°C, the consumption of alcohols was decreased by 17% to 30%. Moreover, the addition of flocculants of PAC/A PAM in the process of hemicelluloses separation, the consumption of organic solvents would be further decreased.

Simultaneous separation and selective conversion of hemicellulose in Pubescen in water–cyclohexane solvent

The simultaneous separation and selective conversion of hemicellulose in Pubescen samples were investigated in water–cyclohexane solvent at 160°C. Chemical titration, X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to characterize the samples. The conversion of hemicellulose in Pubescen sample was found rather selectively in the mixed water–cyclohexane solvent, that is, 86.6% hemicellulose conversion was obtained without significant degradation of cellulose. A maximum acetic acid yield of 13.0wt% was obtained from the conversion of Pubescen. If all the acetic acid comes from the conversion of hemicellulose, the yield would be 90% based on the converted hemicellulose. As compared to water solvent, the mixed solvent played an important role in reducing the conversion rate of hemicellulose, cellulose and lignin. In addition, the reduction of conversion rate of cellulose and lignin was more significant, which benefited the stepwise conversion of different components in raw biomass materials.

Separation and Purification of Hemicellulose by Ultrafiltration

During hydrolysis treatments, where the main objective is the solubilization of hemicelluloses, several undesirable reactions may occur. As a result, monomeric sugars and nonsaccharide compounds are obtained in the liquor. In the present study, autohydrolysis liquor resulting from the corn waste hydrolysis treatment (180 °C, 30 min) was filtered successively increasing the membrane cutoff (1, 5, and 10 kDa) to observe the potential of this technology for hemicellulose purification and fractionation by molecular weight. The experimental results showed that the 10 kDa retentate liquor fraction has the highest hemicellulose concentration (6.10 g/L) and it was constituted by defined molecular weight components (Mw = 2880), with low content in smaller compounds and inorganic material. Hemicelluloses have been isolated from each fraction and were analyzed by different analytical techniques (FT-IR, TGA, 1H NMR, and CHNS–O elemental analysis) to determine that it was possible to improve the physicochemical charac...

Extraction and Separation of Carbohydrates and Phenolic Compounds in Flax Shives with pH-Controlled Pressurized Low Polarity Water

A bench-scale pressurized low polarity water (PLPW) extractor was used for the extraction and separation of hemicellulose, cellulose, lignin, and other phenolic compounds in flax shives. In the first part of this research, the key PLPW extraction process variables of temperature, pH, and flow rate, were optimized using central composite design (CCD). Temperature and pH of water had a significant affect on the fractionation of carbohydrates (cellulose and hemicellulose), lignin, and other phenolics. The optimal extraction conditions for the separation of hemicellulose and lignin, determined by the optimization using CCD, were 170 degrees C, pH 3.0, and a flow rate of 2.5 mL/min. Under these extraction conditions, 39.3% of the initial biomass or feed, 70.1% of the hemicellulose, 35.3% of the lignin, and 5.3% of the cellulose were extracted from the flax shives. In order to improve the purity and yield of the cellulose, a two-stage PLPW extraction was examined. The first stage was designed to remove hemicellulose by water at 170 degrees C and the second stage was intended for delignification by a pH 12 buffer at 220 degrees C. The two-stage PLPW extraction effectively removed 63.2% of the feed, 97.3% of hemicellulose, and 86.3% of lignin, while solubilizing 23.9% of cellulose; resulting in a solid residue containing 0.7 g of hemicellulose, 3.5 g of lignin, and 27.3 g of cellulose/100 g of DFS. The PLPW extraction is able to extract and separate components in flax shives by changing pH and temperature. The best case occurs between pH 9.5 and 12, resulting in maximum solubilization of hemicellulose and lignin.

Two glucuronoyl esterases of Phanerochaete chrysosporium

The white-rot fungus Phanerochaete chrysosporium produces glucuronoyl esterase, a recently discovered carbohydrate esterase, during growth on sugar beet pulp. Two putative genes encoding this enzyme, ge1 and ge2, were isolated and cloned. Heterologous expression in Aspergillus vadensis, Pycnoporus cinnabarinus and Schizophyllum commune resulted in extracellular glucuronoyl esterase activity, demonstrating that these genes encode this enzymatic function. The amino acid sequence of GE1 was used to identify homologous genes in the genomes of twenty-four fungi. Approximately half of the genomes, both from ascomycetes and basidiomycetes, contained putative orthologues, but their presence could not be assigned to any of fungal class or subclass. Comparison of the amino acid sequences of identified and putative glucuronoyl esterases to other types of carbohydrate esterases (CE) confirmed that they form a separate family of CEs. These enzymes are interesting candidates for biotechnological applications such as the separation of lignin and hemicellulose.

Fractional Separation of Hemicelluloses and Lignin in High Yield and Purity from Mild Ball-Milled Periploca sepium

A novel three-step procedure for separation of hemicelluloses and lignin with high yield and purity was proposed in this study, where wood is mildly milled and successively extracted to produce three hemicellulosic and lignin fractions representing the total hemicelluloses and lignin in wood. The sequential treatments of the mild ball-milled Periploca sepium with 80% aqueous dioxane containing 0.05 M HCl at 85°C for 4 h, DMSO at 85°C for 4 h, and 8% NaOH at 50°C for 3 h resulted in a total release of over 85% of the original hemicelluloses and 86% of the original lignin. In particular, approximately 36% of the original hemicelluloses and 50% of the original lignin were separated during the first mild acidolytic hydrolysis process after low intensity milling. The structure of the acidic dioxane-, DMSO-, and alkali-soluble hemicellulosic and lignin fractions were elucidated using wet chemical analysis, FT-IR, and solution-state 1H, 13C, and 31P NMR techniques. Results showed that both the mild ball milling and the mild acidolysis under the conditions given did not affect the separated lignin macromolecular structure. On the other hand, the mild acidolytic hydrolysis condition did cause substantial hemicellulosic depolymerization exception for a significant cleavage the ether linkages between lignin and hemicelluloses. The acidic dioxane-soluble lignin fraction was structurally different from the DMSO- and alkali-soluble lignin preparations and may originate mainly from the primary wall, while the alkali-soluble lignin preparation was mainly released from the secondary wall of Periploca sepium. Furthermore, it was found that the acidic dioxane-soluble hemicelluloses mainly contained more branched and less acidic arabinoxylans, and the 8% NaOH-soluble hemicellulosic fraction H3 was both less branched and less acidic in structure, whereas the DMSO-soluble hemicelluloses were more acidic but less branched and consisted mainly of 4-O-methylglucuronoarabinoxylan.