Hemicellulose Yield Research Articles

Hemicellulose based biorefinery from pineapple peel waste: Xylan extraction and its conversion into xylooligosaccharides

Pineapple peel waste was utilized as an unexplored source of hemicellulose (31.8±1.9%) for value addition. Hemicellulose was extracted by an alkali-based method, where the peels were incubated at different alkali concentrations (5%, 10% and 15% w/v) at temperatures ranging from 35°C to a maximum of 65°C for a fixed period of 16h. A maximum recovery of hemicellulose (95.9±2.0%) was observed after incubating extractive-free pineapple peels in 15% (w/v) alkali solution for 16h at 45°C. Higher incubation temperatures (65°C) for 16h, resulted in a lower yield of hemicellulose (81.7±3.7%) which can be attributed to the disintegration of the hemicellulose structure due to large severity factor (temperature–time combination). With low severity factor, it was noted that higher yields (96.6±0.3%) were obtained 65°C, 4h). Hydrothermal-assisted alkali extraction was also evaluated for maximizing the recovery of pineapple peel hemicellulose. The maximum relative recovery of ˜87.6% was obtained with 10% (w/v) alkali at the end of 1.5h of hydrothermal pretreatment (121°C and 15psi pressure). The hemicellulose extracted by hydrothermal-assisted alkali pretreatment was enzymatically hydrolyzed to produce XOS and the process was optimized in terms of enzyme dose (U), temperature (°C), pH and time (h). Direct hydrolysis of pineapple peels with dilute nitric acid produced xylose-rich liquor (˜91% xylose yield) at 0.5% nitric acid, reaction time of 1h and solid–liquid ratio of 1:20. The xylose-rich liquor could be converted to potential chemicals such as xylitol.

Alkaline extraction and characterization of residual hemicellulose in dissolving pulp

Residual hemicellulose in dissolving pulp is known as a reason for deterioration of final product quality and processability problems during cellulose derivative production. However, the issue caused by the residual hemicellulose is not fully understood and is primarily based on industrial experience. To better understand the effect of hemicellulose on cellulose derivative process, hemicellulose in prehydrolysis kraft hardwood dissolving pulp was extracted and its glycosidic linkage structure was thoroughly analysed. Two-stage alkaline extraction, consisting of 24 wt% KOH solution and 18 wt% NaOH with 4 wt% H3BO3 solution, was found effective for the sequential extraction of high purity xylan and glucomannan from the dissolving pulp. Considering the purity and yield of extracted xylan, room temperature for Stage-1 KOH extraction condition was preferred, while 1 °C was preferred for Stage-2 NaOH extraction. Mechanical refining treatment at a mild condition improved the extraction yield of hemicellulose, although the molecular weight of the cellulose was reduced with severe refining condition. Glycosidic linkage analysis showed that native 4-O-methylglucuronic acid side groups were removed during pulping process, resulting in a linearized xylan structure, while a high amount of glucuronic acid was detected in commercial beechwood xylan. The extracted hemicellulose from the second stage showed relatively high number of branched backbone unit e.g., 1,4,6-linked mannose and 1,4,6-linked glucose. The protocol developed in this study should be useful for hemicellulose-related applications.

Hydrothermal extraction of hemicellulose: from lab to pilot scale

A flow-through reactor for hemicelluloses extraction with hot pressurized water was scaled with a factor of 73. System performance was evaluated by comparing the temperature profile, extraction yield and kinetics of the two systems, performing experiments at 160 and 170°C, 11barg for 90min, using catalpa wood as raw material. Hemicellulose yields were 33.9% and 38.8% (lab scale 160°C and 170°C) and 35.7% and 41.7% (pilot scale 160°C and 170°C). The pilot reactor was upgraded by designing a manifold system capable to provide samples with different liquid residence time during the same experiment. Tests at 140, 150, 160 and 170°C were carried for 90min. Increasing yields (9.3–40.6%) and decreasing molecular weights (4078–1417Da) were obtained at increasing the temperature. Biomass/water ratio of 1/27 gave total average concentration of xylose of 0.4g/L (140°C) to 1.8g/L (170°C).

Coupling the pretreatment and hydrolysis of lignocellulosic biomass by the expression of beta-xylosidases.

Thermochemical pretreatment and enzymatic hydrolysis are the areas contributing most to the operational costs of second generation ethanol in lignocellulosic biorefineries. The improvement of lignocellulosic enzyme cocktails has been significant in the recent years. Although the needs for the reduction of the energy intensity and chemical consumption in the pretreatment step are well known, the reduction of the severity of the process strongly affects the enzymatic hydrolysis yield. To explore the formulation requirements of the well known cellulolytic cocktail from Myceliophthora thermophila on mild pretreated raw materials, this cocktail was tested on steam exploded corn stover without acid impregnation. The low hemicellulose yield and significant accumulation of xylobiose compared with the standard pretreated material obtained with dilute acid impregnation evidenced a clear limitation in the conversion of xylan to xylose. In order to complement the beta-xylosidase limitation, a selection of enzymes was expressed and tested in this fungus. A controlled expression of xylosidases from Aspergillus nidulans, Aspergillus fumigatus, and Fusarium oxysporum allowed recovering hemicellulose yields reached with standard acid treated material. The results underline the need of parallel development of the pretreatment process with the optimization of the formulation of the enzymatic cocktails.

Microwave-assisted alkali extraction of bagasse hemicellulose enhanced by an enzymatic pretreatment process

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.

Hydrothermal and microwave assisted alkali pretreatment for fractionation of arecanut husk

Alkaline pretreatment assisted with hydrothermal and microwave irradiation as heating mechanisms were evaluated for their efficiency to develop a lignocellulosic biorefinery from arecanut husk. Hydrothermal treatment was carried out at 121°C for 1, 1.5 and 2h and microwave irradiation was performed at three power levels of 900, 540 and 180W at two time periods (1 and 3min). Hydrothermal treatment (1h) of biomass soaked in 20% w/v NaOH solution resulted in average recovery of 82% hemicellulose with 69.7% lignin removal. Whereas, for hydrothermal treatment (1h) of alkali-biomass mixture (no soaking), 74.9% of hemicellulose were recovered with 64.6% lignin removal. Increasing the reaction time from 1 to 1.5h resulted in significant increase in average hemicellulose yield (83.5%). However, prolonging hydrothermal treatment time to 2h did not result in further increase in average hemicellulose yield (82.3%). The residue obtained after hydrothermal pretreatment (1.5h) was concentrated in cellulose (average 69.2%). Compared to hydrothermal treatment, microwave treated biomass yielded low hemicellulose recovery and maximum yield (52%) was obtained at 900W and 3min exposure. FTIR analysis confirmed the presence of functional groups associated with xylan of hemicellulose precipitate. Enzymatic hydrolysis of pretreated residue (unbleached and bleached) using cellulase and β- glucosidase released 75–79% reducing sugars from cellulose. The amount of glucose released from pretreated biomass was 71.5±1.9% in comparison to 2.2±0.1% as obtained from enzymatic hydrolysis of untreated biomass. Thus, the developed process generated cellulose rich residue, hemicellulose as precipitate and liquor rich in lignin.

Hydrodynamic cavitation as an efficient pretreatment method for lignocellulosic biomass: A parametric study

Hydrodynamic cavitation (HC), which is a highly destructive force, was employed for pretreatment of sugarcane bagasse (SCB). The efficacy of HC was studied using response surface methodology (RSM) with determining parameters varied: inlet pressure of 1–3bar, temperature of 40–70°C, and alkaline concentration of 0.1–0.3M. At the best condition (3bar, 70°C and 0.3M NaOH), 93.05% and 94.45% of hydrolysis yield of cellulose and hemicellulose, respectively, were obtained within 30min of pretreatment time. Also, pretreatment time higher than 10min had little to do regarding to SCB composition changes using different orifice plates (16 and 27 holes, with corresponding cavitation number of 0.017 and 0.048, respectively), with higher hydrolysis yield observed at 20min of process. Therefore, HC-based approach could lead to a high yield of hydrolysis, as long as a treatment condition was right; it could be so at mild conditions and at short running time.

Formic acid aided hot water extraction of hemicellulose from European silver birch (Betula pendula) sawdust

Hemicellulose has been extracted from birch (Betula pendula) sawdust by formic acid aided hot water extraction. The maximum amount of hemicellulose extracted was about 70mol% of the total hemicellulose content at 170°C, measured as the combined yield of xylose and furfural. Lower temperatures (130 and 140°C) favored hemicellulose hydrolysis rather than cellulose hydrolysis, even though the total hemicellulose yield was less than at 170°C. It was found that formic acid greatly increased the hydrolysis of hemicellulose to xylose and furfural at the experimental temperatures. The amount of lignin in the extract remained below the detection limit of the analysis (3g/L) in all cases. Formic acid aided hot water extraction is a promising technique for extracting hemicellulose from woody biomass, while leaving a solid residue with low hemicellulose content, which can be delignified to culminate in the three main isolated lignocellulosic fractions: cellulose, hemicellulose, and lignin.

Characterization and components separation of corn stover by alkali and hydrogen peroxide treatments

Abstract The dissolution of corn stover in alkaline solvent system composed of NaOH-H2O2 was reported and the separation of its ingredients combined with acid precipitation, ethanol extraction was proposed. It is proven that the residual after alkali solvent was cellulose, the filtrate by the acid precipitation of the liquor was lignin, the solid by the ethanol extraction of the liquor was hemicellulose. The optimum dissolution conditions were determined by single-factor experiment as follows: the concentration of H2O2 5.0%, pH 11.5, dissolution temperature 60°C, dissolution time 3.0 h, the ratio of liquid to solid 30 mL/g. And chemical analysis were employed to determine the purity of the components separated. The structure of the components separated were identifi ed by FT-IR, SEM, XRD and NMR. The cellulose recovery yield can achieve to 84.2% and lignin recovery yield is 86.6%, the hemicellulose recovery yield is 96.7%. After recycling the solvent 3 times, the recovery yield of cellulose, lignin and hemicellulose were 82.7, 87.6 and 97.4%, and the purity of cellulose, lignin and hemicellulose were 98.0, 96.5 and 98.7%, respectively.

Effects of Liquid-to-Solid Ratio and Reaction Time on Dilute Sulfuric Acid Pretreatment of Achnatherum splendens

For ammonia-sulfuric acid pretreatment of Achnatherum splendens, the ground biomass was first pretreated by soaking in aqueous ammonia with 10 wt% of ammonia at 55 degrees C with 12:1 of liquid-to-solid ratio (based on wt) for 36 h. Then the pretreated solids were further treated with 0.5-2% (w/v) sulfuric acid at liquid-to-solid ratio of 8:1-15:1 (v/w) for 0.5-3 h at 100 degrees C. Increasing sulfuric acid concentration and reaction time in the second stage had significant effect on hemicellulose solubilization. Increases in sulfuric acid concentration and reaction time in the second stage caused significant decrease in hemicellulose and significant increases in cellulose and ligning. However, liquid-to-solid ratio had no significant effects on hemicellulose solubilization in the second stage. Liquid-to-solid-ratio had also no significant effects on the yield of hemicellulose, cellulose and lignin in the solids after sulfuric acid pretreatment in the second stage. The optimum treatment conditions of the ammonia-sulfuric acid pretreatment were: 10 wt % of ammonia, 55 degrees C, 36 h of reaction time, 12:1 of liquid-to-solid ratio (based on wt) in the first stage

Catalysis-a potential alternative to kraft pulping

A thorough analysis of the kraft pulping process makes it obvious why it has dominated for over a century as an industrial process with no replacement in sight. It uses low-cost raw materials; collects and regenerates over 90% of the chemicals needed in the process; and is indifferent to wood raw material and good at preserving the cellulose portion of the wood, the part that provides strong fibers. Although the process is odiferous, extremely capital intensive, and very poor at preserving hemicellulose yield, no alternatives have been able to replace it for process cost and product quality. There is a misconception that no new pulping processes have been discovered since the discovery of kraft pulping. Besides the minor adjustments—such as anthraquinone or polysulfide— chlorine, chlorite, and peracetic acid holopulping were discovered and evaluated decades ago. Various solvent pulping methods were discovered and evaluated in the 1980s and 1990s. This work continues with ionic solvents, deep eutectic solvents, and most recently protic ionic liquids. Where all these alternative processes fail is process cost. The chemicals are too expensive and too difficult to recover for use in a commercial process to produce wood pulp. The premise of this review is that the only way to achieve better performance and lower cost than the existing kraft pulping process will be a process using a catalyst to control and direct the reactions. With a high enough reaction rate and a sufficiently high number of turnovers, even an expensive catalyst can still be low cost. We reviewed the literature of existing pulping and delignification catalysts and propose research areas of interest for more intensive experimental efforts.

Innovative pretreatment of sugarcane bagasse using supercritical CO2 followed by alkaline hydrogen peroxide

An innovative method for pretreatment of sugarcane bagasse using sequential combination of supercritical CO2 (scCO2) and alkaline hydrogen peroxide (H2O2) at mild conditions is proposed. This method was found to be superior to the individual pretreatment with scCO2, ultrasound, or H2O2 and the sequential combination of scCO2 and ultrasound regarding the yield of cellulose and hemicellulose, almost twice the yield was observed. Pretreatment with scCO2 could obtain higher amount of cellulose and hemicellulose but also acid-insoluble lignin. Pretreatment with ultrasound or H2O2 could partly depolymerize lignin, however, could not separate cellulose from lignin. The analysis of liquid products via enzymatic hydrolysis by HPLC and the characterization of the solid residues by SEM revealed strong synergetic effects in the sequential combination of scCO2 and H2O2.

Autohydrolysis and aqueous ammonia extraction of wheat straw: effect of treatment severity on yield and structure of hemicellulose and lignin

Pseudo-lignin accumulation in wheat straw autohydrolysis was revealed by relative double detection high-performance size-exclusion chromatography and confirmed by CuO oxidation.

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.

Acid-catalyzed hydrothermal severity on the fractionation of agricultural residues for xylose-rich hydrolyzates

The objective of this work was to investigate the feasibility of acid-catalyzed hydrothermal fractionation for maximum solubilization of the hemicellulosic portion of three agricultural residues. The fractionation conditions converted into combined severity factor (CS) in the range of 1.2–2.9. The highest hemicellulose yield of 87.88% was achieved when barley straw was fractionated at a CS of 2.19. However, the maximum glucose release of 15.29% was achieved for the case of rice straw. The maximum productions of various by-products were observed with the fractionation of rape straw: 0.88g/L of 5-hydroxymethylfurfural (5-HMF), 2.16g/L of furfural, 0.44g/L of levulinic acid, 1.59g/L of formic acid, and 3.06g/L of acetic acid. The highest selectivities, a criterion for evaluating the fractionation of 21.55 for fractionated solid and 7.48 for liquid hydrolyzate were obtained from barley straw.

Binding Ability of Corn Cobs Hemicellulose toward Cadmium

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.

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.

Process Optimization of Hemicelluloses Lye Extraction from Sugarcane Bagasse

Sugarcane bagasses were used as raw materials to produce the hemicelluloses, and the effects of temperature, alkali consumption, time and liquid to solid ratio on the extraction yield of hemicelluloses were investigated. Through the analysis of the response surface method, results were concluded that the best extraction process conditions were as follows: NaOH concentration 10.60%, extraction time 4.34 h, solid-liquid ratio 1:40.59, actual extraction rate is 31.486%, corresponding to the model prediction 31.4447% basically.

Effect of extraction conditions on hemicellulose yields and optimisation for industrial processes

AbstractHemicellulose is a valuable component of agro‐food industrial wastes and used in various areas such as drug manufacture and food industry for encapsulation and emulsification. In this study, effects of raw material type, particle size, and extraction conditions (alkaline concentration, temperature, time) and methods (direct alkaline extraction, alkaline extraction after component removal and acidic extraction method) on hemicellulose yields were investigated. Sugar beet pulp and corn wastes were used as raw material. The alkaline method resulted in 40.2% pure extracts, while the acidic method gave only 27.4% purity in the same extraction conditions. The optimal extraction conditions were found as 30 °C temperature, 10% alkali (NaOH) and 24 h time (64.3%). It was also observed that removal of constituents such as fat, protein, starch and soluble sugar increased the purity of hemicellulose from 40.2% to 58.2% at the same conditions. The results indicated that using both low alkaline concentration and low temperature allows to recover higher‐quality extracts.

Hot-water extraction of ground spruce wood of different particle size

Hot-water extraction of hemicelluloses, especially galactoglucomannans, from fractions of ground spruce wood with different particle sizes was studied at 170°C with extraction times up to 60 min. Extraction of spruce sapwood, heartwood, and thermomechanical pulp (TMP) was also compared at 160 to 180°C. Static batch extractions were carried out in an accelerated solvent extractor (ASE). The extracted hemicelluloses were characterized by sugar unit analysis and determination of acetyl groups and molar masses. The particle size significantly affected the extraction of ground wood. The total extraction yield, as well as the yields of hemicelluloses and monosaccharides, was the highest from the finest ground wood fraction (< 0.1 mm). The release of acetic acid, average molar mass of extracted hemicelluloses, and end-pH of the extracts were also dependent of the particle size, although to a lower extent. Irrespectively of the ground wood particle size, the yield of hemicelluloses reached a plateau after 40 min extraction at 170°C. The results indicate that extraction of hemicelluloses is limited mainly by the diffusion in the fiber wall, and for coarse wood shives also by the mass transfer in the wood matrix. There were only small differences in the hot-water extraction yields of hemicelluloses from spruce sapwood, heartwood, and TMP, considering both poly- and monosaccharides.