Removal Of Hemicellulose Research Articles

Optimization of binary acids pretreatment of corncob biomass for enhanced recovery of cellulose to produce bioethanol

Lignocellulosic agricultural wastes are the most widely utilized resource for bioethanol production due to several advantages. Removal of hemicellulose and lignin is a prerequired step during bioethanol production from lignocellulosic biomass to upgrade cellulose recovery and the substrate porosity for saccharification. Chemical pretreatment of corncob was performed in the current research applying binary acids (H2SO4 + CH3COOH) in different ratios. The attained maximum removal of lignin and hemicellulose were 81.41 ± 2.3% and 85.6 ± 1.8%, respectively, with enhanced cellulose recovery of 93.5 ± 1.3% at the optimum conditions of binary acids concentration (3%, v/v), biomass loading ratio (0.1 g/mL), pretreatment temperature (120 °C) and time (60 min). The SEM, FTIR and XRD results revealed the removal of hemicelluloses and lignin from the corncob biomass by binary acids pretreatment and confirmed a change in the crystallinity index of corncob biomass. Ethanol fermentation was accomplished at 30 °C at 200 rpm for 4 days with the hydrolysates using Saccharomyces cerevisiae and obtained a maximum bioethanol concentration of 24.6 mg/mL. This study demonstrates that binary acids pretreatment is an alternative approach for the pretreatment of lignocellulosic biomass. The optimized process conditions could also increase cellulose recovery and bioethanol yield.

Highly sustainable cascade pretreatment of low-pressure steam heating and organic acid on pineapple waste biomass for efficient delignification

Cascade pretreatment of low-pressure steam heating (LPSH) and maleic acid (MA) on pineapple waste (PW) biomass aims to improve delignification, increase enzyme accessibility to carbohydrate in the feedstock while reducing inhibitor by-products. The best conditions for LPSH pretreatment were determined using one-factor-at-a-time (OFAT) while the conditions of MA pretreatment (temperature, acid concentration and time) were optimized by Box-Behnken design. A total of 68% (w/w) delignification with 79.5% (w/w) hemicellulose removal were achieved while 77.6% (w/w) cellulose was retained in the solid residue after the cascade pretreatment. No 5-hydroxylmethyl furfural (5-HMF) and acceptable furfural (1.8 g/L) were detected in the hydrolysate by high performance liquid chromatography analysis, with negligible amount of phenolic compounds (0.01 g/L). Compared to the pretreatment with combined LPSH and conventional sulphuric acid pretreatment (H2SO4), the pretreated PW produced 3.6 g/L of furfural and 0.4 g/L of HMF at similar optimized conditions. The pretreated PW were further characterized by scanning electron microscopy and Fourier transform infrared spectroscopy to analyze structural morphology and functional group changes. The pooled solid and liquid hydrolysate fractions generated from the LPSH and MA cascade pretreatment and subsequent enzyme hydrolysis has successfully generated 356.32 mg/g glucose and 156.91 mg/g xylose. The optimized cascade pretreatments provide up to 54.79% of glucose yield and 69.23% of xylose yield. Furthermore, 67.87% reduction of lignin content from the cascade pretreatment can substantially enhance the glucose yield up to 95.76% and xylose yield up to 99.07% during enzymatic hydrolysis using the mixture of cellulase and hemicellulase.

Thermal kinetics and morphological investigation of alkaline treated rice husk biomass

Agro waste bio mass are creating challenges for environment in term of air pollution due to improper disposal. Rice milling is the process in which rice husk is produced as by-product. The agro-waste rice husk has tremendous potential to be used either in its raw form or in ash form. The inherent component of this waste cellulose provides enhanced properties in a reinforced composite when used as filler. Rice husk is the hard outer layer and covering rice seed, which makes reinforcement challenging in its original form. Fiber surface treatment significantly improves adhesion with matrix and various thermo chemical properties of filler as well as of composites. NaOH treatment is cost-effective and it ensures the adhesion with matrix by removal of hemicellulose and lignin. The chemical treatment of agro-waste (rice husk) is performed with 5% alkali solutions of NaOH in water. Results are compared with the properties of untreated rice husk for thermal and morphological characterizations. In the present work, we are trying to quantify the impact of chemical treatment on rice husk thermal decomposition and its kinetics. Thermogravimetric analysis and kinetics study of thermal degradation, provide key input towards pyrolysis pattern of rice husk, while FTIR and SEM analysis provide the prospects of this bio filler using a reinforcing agent to develop green composite and productive disposal. The FTIR data helps to find the possibilities of blending different bio fillers and natural fibers to find suitable reinforcing substances. The average activation energy of treated fiber is noted as 137.95 by KAS method and 108.08 by FWO method as compared to 55.56 by KAS method & 54.26 by FWO method for untreated rice husk.

Effect of Acetylation and Accelerated Weathering of Nigerian Grown Rubberwood (Hevea brasiliensis, Müll. Arg.) on Equilibrium Moisture Content and Colour Change

This study was conducted to investigate the effect of acetylation on equilibrium moisture content (EMC) of Nigerian-grown rubberwood and its effect on colour change in exposure of rubberwood to surface degradation through accelerated weathering. The samples were modified to two levels of acetylation, which yielded weight percent gain (WPG) of 7 % and 10 % after 8hr (8-hr Acetyl) and 48hr of acetylation (48-hr Acetyl), respectively. Accelerated weathering of unmodified (Ref) and acetylated wood was done using QUV-Accelerated Weathering Tester for four weeks. The unmodified and acetylated samples (weathered and unweathered) were oven-dried and conditioned in climate rooms at different relative humidity of 50 %, 65 % and 95 %, with samples being moved to each room after 14 days. Results showed that acetylation led to a significant decrease in equilibrium moisture content of rubberwood. After weathering, there was a decrease in EMC of rubberwood due to removal of hemicelluloses alongside the degraded lignin, and a slight increase in EMC of the acetylated wood. In terms of colour change, photo-bleaching of the acetylated samples was higher (10.46 for 48-hr Acetyl) after four weeks of weathering compared to the unmodified samples (6.43). Hence, the outcome of this study has shown that, although acetylation is effective in minimizing moisture ingress into wood, it resulted in photo-bleaching of the weathered samples. Additional surface coating is recommended to serve as a protective layer, preventing partial washing out of the acetyl groups, minimize photo-bleaching during weathering and prolong the aesthetic value of the wood especially in outdoor applications such as wall cladding and façade.

Delignification efficiency of various types of biomass using microwave-assisted hydrotropic pretreatment

The use of a method of an effective delignification of lignocellulosic biomass is a key stage of designing processes of its microbiological conversion e.g. for the purposes of the production of cellulosic ethanol. The study was aimed at evaluating the effectiveness of microwave-assisted hydrotropic pretreatment using sodium cumene sulfonate (NaCS) for the delignification of pine and beech chips and wheat straw. Research results presenting the impact of process parameters of microwave-assisted hydrotropic delignification confirm a high effectiveness of this method of pretreatment of lignocellulosic biomass. The observed effects included changes in the composition of the biomass and an increased susceptibility of cellulose to the subsequent enzymatic hydrolysis. The use of microwave heating combined with an addition of hydrotrope of 40% w/v NaCS and 117 PSI for 60 min enabled a reduction of the absolute concentration of lignins by 36.58% in pine chips, by 57.68% in beech chips, and by 74.08% in wheat straw. After enzymatic hydrolysis was conducted, the highest concentration of glucose: 463.27 ± 11.25 mg glucose/g (hydrolysis yield 46.76 ± 1.14%) was obtained from the wheat straw, while 327.70 ± 22.15 mg glucose/g (hydrolysis yield 35.13 ± 2.37%) was acquired from the beech chips, and only 50.77 ± 0.75 mg glucose/g (hydrolysis yield 6.63 ± 0.10%) was obtained from the pine chips. Microwave-assisted hydrotropic delignification in the optimum process conditions additionally allows a complete removal of hemicellulose from biomass, which improves the effectiveness of enzymatic hydrolysis. Due to a significant reduction of lignin and hemicellulose concentration in biomass, cellulose—which is susceptible to enzymatic hydrolysis and a source of carbon in biosynthesis processes—becomes the main biomass component.

High yield of fermentable sugar from paper mulberry woods using phosphoric acid plus hydrogen peroxide pretreatment: Multifactorial investigation and optimization

Paper mulberry wood contains a high cellulose content of 59%, making it a potentially excellent feedstock for recovery of fermentable sugar used in bioethanol production. This potential was usefully exploited by establishing the optimal phosphoric acid plus hydrogen peroxide pretreatment of its woods using the response surface methodology. Pretreatment temperature, H3PO4 proportion in pretreatment mixture, and time significantly corelated with the removal of non-cellulosic polymers, cellulose recovery, enzymatic hydrolysis of the recovered cellulose, and glucose yield. At the optimized conditions of 34.7 ⁰C, 71.3% w/w H3PO4 proportion (the corresponding H2O2 proportion of 4.84% w/w), and 3.3 h, there were 97% biomass delignification, 100% hemicellulose removal, and high recovery of a cellulose-rich substrate characterized by decreased crystallinity, enhanced porosity, and complete glucose digestibility. The obtained high glucose yield of 493 mg/g raw wood was comparable to the best-reported yields from short-rotation woody energy crops.

Organosolv fractionation of a lignocellulosic biomass feedstock using a pilot scale microwave-heating reactor

Bamboo is among the short-rotation and dedicated energy crops which serve as lignocellulosic feedstock for future bio-refinery. A pilot scale microwave fractionation system (PMFS) was developed and used for the organosolv fractionation of bamboo sawdust. The key component of the system, a 1000 L microwave-heating reactor, was designed with unique features for high efficiency of microwave energy utilization and uniform temperature distribution. More than 800 kg reactant can be heated at 65% energy efficiency with temperature differences between top and bottom reactor positions of less than 4 °C. The operational parameters of the PMFS were investigated, and the fractionation products from the PMFS process were characterized and compared with those obtained from lab scale experiments. Higher lignin (93.2%) and hemicellulose (84.7%) removal rates without serious cellulose degradation (cellulose retention 89.1%) were achieved with the PMFS. Recovered lignin has relatively narrow molecular weight distributions (polydispersity index ≈ 2). The mass balance of the fractionation process showed that 81.5% utilization efficiency of the bamboo feedstock was obtained by organosolv fractionation with the PMFS. The results from this study provide insightful information for the industrial implementation of microwave-assisted thermochemical conversion of lignocellulosic biomass.

Extraction of Sugars and Cellulose Fibers from Cannabis Stems by Hydrolysis, Pulping, and Bleaching

AbstractCannabis indica stems were hydrolyzed with subcritical water at various temperatures, reaction times, and feed concentrations. The highest total yield of reducing sugars of 16.4 wt % was obtained at 190 °C in 37.5 min with a feed concentration of 3.5 wt %. Solid residues from the optimized process were treated with 0.5 M NaOH (pulping) and 0.5–3 % H2O2 (bleaching) to isolate cellulose fibers. The maximum yield of cellulose was 34.8 wt % with lowest lignin content of 0.5 wt %. With the removal of hemicellulose and lignin through the integrated hydrothermal processes, the crystallinity index and thermal stability of the cellulose fibers increased.

A Comparative Investigation on Structural and Chemical Differences between the Pith and Rind of Sunflower Stalk and Their Influences on Nanofibrillation Efficiency

The structure and chemical composition of cell walls play a vital role in the bioconversion and utilization of plants. In the present study, the cell wall structure and chemical composition of pith and rind from sunflower stalks were compared and correlated to their nanofibrillation efficiency with ultrasonic treatment. Mild chemical pretreatment using 1% or 4% NaOH without any bleaching process were applied prior to ultrasonication nanofibrillation. Significant structural and chemical differences were demonstrated between the pith and rind, with the former exhibiting a much lower lignin and hemicellulose contents, higher pectin, much looser cell structure and higher cell wall porosity than the latter. Alkaline treatment alone was sufficient to eliminate most of the hemicellulose and pectin from stalk pith, whereas only partial removal of hemicellulose and lignin was achieved for the woody rind part. After 30 min of ultrasonic treatment, the stalk pith exhibited fully defibrillated fibrils with a continuous and entangled micro/nanofibrillated network, whereas numerous micron-sized fiber and fragments remained for the rind. The results indicated that stalk pith is less recalcitrant and easier to be fibrillated with ultrasonication than rind, which must be correlated to their distinct differences in both structure and chemical composition.

Efficient Swelling and Mercerization of Bagasse Fiber by Freeze-Thaw-Assisted Alkali Treatment

The mercerization of fiber is an important method for the high-value utilization of cellulose. In this study, the bagasse fiber was mercerized by freeze–thaw-assisted alkali treatment (FT/AT). The effects of freezing temperature, freezing time, alkali concentration, and thawing temperature on cellulose and hemicellulose removal were studied. The optimal freezing temperature was −40°C, freezing time was 8.0 h, alkali concentration was 5.0%, and thawing temperature was 30°C. The highest removal rate of hemicellulose was 75.64%. It was 5.80% higher than that of alkali treatment (AT). The alkaline degradation of cellulose was inhibited. The penetration of alkaline solution to fiber was promoted by the assistance of freeze-thaw pretreatment. The effective alkali concentration (5.0%) of cellulose I completely transformed into cellulose II decreased by 66.67% compared with traditional alkaline mercerization (15.0%). The high-efficiency mercerization of fiber was achieved by FT/AT. It provides theoretical support for promoting the high-value utilization of lignocellulosic biomass.

Effects of Microwave-Assisted Liquid Hot Water Pretreatment on Chemical Composition and Structure of Moso Bamboo.

The effects of microwave assisted liquid hot water (MA-LHW) pretreatment on the chemical composition of Moso bamboo were investigated, and the fiber structure of pretreated residues were studied. The results showed that MA-LHW pretreatment had high selectivity for the degradation of hemicellulose in Moso bamboo, and the extracted hemicellulose could be used to prepare xylooligosaccharide through enzyme depolymerization. The degradation rates of cellulose and lignin after MA-LHW pretreatment were only 14.73% and 7.18%, which were significantly lower than those of LHW pretreatment; 155.0 mg/g xylobiose and 61.0 mg/g xylotrisoe can be obtained after enzymatic hydrolysis, and the yield of xylo-oligosaccharide reached 80.59% of the theoretical conversion rate. MA-LHW pretreatment increased the removal of hemicellulose, lignin, and other non-crystalline parts in bamboo materials, and more cellulose with crystalline structure was retained, which increased the CrI value of Moso bamboo by 14.84%. FTIR spectra showed that the characteristic peak intensity of hemicellulose was significantly reduced after MA-LHW pretreatment, which confirmed the selective degradation of hemicellulose by MA-LAW pretreatment. Moreover, MA-LHW pretreatment also destroyed O-H, C-H, C-O-C, and β-glucoside bonds in Moso bamboo fiber, caused by the recombination and synthesis of some groups (-CH2 and C=O) of cellulose, hemicellulose, and lignin destroyed under pretreatment conditions.

Structural and thermal study of hemicellulose and lignin removal from two types of sawdust to isolate cellulose

Structural and thermal study of hemicellulose and lignin removal from two types of sawdust to isolate cellulose

Enhanced Mechanical Properties of Polyvinyl Chloride-Based Wood-Plastic Composites With Pretreated Corn Stalk.

Wood–plastic composites (WPCs) are a type of environmentally friendly materials widely used in daily life. This paper selected low-value biomass, corn stalk (CS), as the lignocellulosic resource for polyvinyl chloride (PVC)-based WPCs. To depict the relationship between lignocellulosic composition (cellulose, hemicellulose, and lignin) and mechanical performance of WPCs, pretreatments have been optimized to selective removal of lignin using an alkaline-EtOH stewing process and selective removal of hemicellulose using an acid stewing process. The αC sample, in which both lignin and hemicellulose were removed, shows the highest degree of crystallinity (72.60%) as estimated from X-ray diffraction analysis results and fibrous morphology with the highest aspect ratio as seen in scanning electron microscopy images. Compared with PVC/CS, PVC/αC gives a substantial increase in tensile strength and modulus by 37.21 and 21.66% and flexural strength and modulus by 29.98 and 34.88%, respectively. These improvements lie in the reinforcing effect of a fibrous structure and the improved interfacial compatibility as proven by scanning electron microscopy and dynamic mechanical analyzer results. Considering the extracted lignin and hemicellulose can be further developed to valuable biochemicals, the pretreatment to CS adds value to both WPC materials and biorefinery products.

Deconstruction of Poplar Wood using Peracetic Acid and FeCl3 in Hot Water

AbstractThe deconstruction of lignocellulose biomass is a key step in biorefinery that requires directional control and high efficiency. Peracetic acid and FeCl3 were adopted in this study during hot water pretreatment, so that the directional deconstruction of poplar wood was enhanced, boosting the subsequent separation of hemicellulose and enzymatic hydrolysis of the remaining biomass, avoiding the necessity of employing high temperature and pressure. A hemicellulose removal (as in xylan) of 98.23 % was achieved. The pretreatment conditions were: 5.7 w/v% peracetic acid, 0.05 mol L−1 FeCl3, 100 °C for 60 min; the results obtained were: 88.63 % hemicellulose removal (as in xylan), 73.38 % cellulose recovery rate, and 85.92 % cellulose enzymatic saccharification rate. The structure, crystallinity, morphology, and surface chemistry of samples were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, and X‐ray photoelectron spectroscopy. The results showed that efficient pretreatment and cellulose enzymatic saccharification could be achieved under moderate pretreatment conditions, promising good potential in biomass conversion.

An insight - A statistical investigation of consolidated bioprocessing of Allium ascalonicum leaves to ethanol using Hangateiclostridium thermocellum KSMK1203 and synthetic consortium

Bioethanol can be produced by cellulolytic and ethanogenic bacterial species could efficiently degrade lignocelluloses and have potential for biofuels production through consolidated bioprocessing (CBP). In this study, on-site cellulase production followed by saccharification and fermentation of pre-treated Allium ascalonicum leaves to bioethanol in a single reactor using Hangateiclostridium thermocellum KSMK1203 and consortium of Cellulomonas fimi MTCC 24 and Zymomonas mobilis MTCC 92. A. ascalonicum leaf pre-treatment with different alkalis and different pre-treatment conditions such as alkali dosage and time for proficient removal of hemicellulose and cellulose recovery was optimized using RSM method with the maximum hemicellulose removal of 85.25%. The essential medium components were screened through PBD and further optimized using RSM method for H. thermocellum KSMK1203 and the consortium for maximized bioethanol yield. Hence, this study proposed that wild-type H. thermocellum KSMK1203 strain and consortium could be used for cellulase secretion and simultaneous bioethanol conversion.

Hydrothermal pretreatment optimization and deep eutectic solvent pretreatment of lignocellulosic biomass: An integrated approach

The combined effect of hydrothermal (HT) and deep eutectic solvent (DES) pretreatment on hemicellulose and lignin removal was studied to enhance cellulose digestibility during saccharification. The operating conditions (water loading and time) for HT pretreatment of sugarcane bagasse (SB) were optimized using response surface methodology (RSM). The SB optimum conditions were applied to other biomass with similar lignin and hemicellulose composition (rice straw (RS) and napier grass (NG)). The HT solids were further subjected to DES pretreatment using ChCl/LA (1:2). The pretreatment efficiency was compared between untreated, HT, ChCl/LA, and HT-ChCl/LA treated solids based on the glucose yield during saccharification. The hemicellulose recovery and delignification were higher in HT-ChCl/LA solids compared to HT and ChCl/LA solids. During saccharification (72 h) of HT- ChCl/LA solids, the glucose yield increased 3.1, 3.4, and 2.9-times for SB, RS, and NG, respectively. Hemicellulose and lignin obtained at different pretreatment stages could benefit the biorefineries.

Coupling of pretreatment and pyrolysis improving the production of levoglucosan from corncob

Influence of organic biphasic pretreatment on levoglucosan (LG) yield from biomass pyrolysis was investigated with dilute sulfuric acid and dilute sodium hydroxide pretreatment as comparison, simultaneously, the mechanism was explored in depth. It was found that with monophasic (water) conditions, dilute sulfuric acid and dilute sodium hydroxide pretreatment, the yield of LG was all increase largely (from untreated 28% to treated 60–85%) due to the removal of hemicellulose or lignin. Phenoxyethanol was introduced to construct a biphasic system, and it showed that acid biphasic pretreatment of corncob followed by pyrolysis at 450 °C increased the LG yield to 91% and limited the formation of by-products, especially acids, ketones, and esters. In addition, it can easily realize the efficient recovery of the removed hemicellulose (75%) and lignin (49%). The different LG yields implied that removing lignin is more effective in increasing LG than removing hemicellulose. These findings provide instruction for the highly selective production of anhydrous sugars from biomass waste.

Poly-(vinyl alcohol) composite films reinforced with carboxylated functional microcrystalline cellulose from jute fiber

Bio-based materials have attracted ample research interest due to their intrinsic beneficial impact on human society. Microcrystalline cellulose (MCC) extracted from a variety of bioresources is one of the most prominent candidate in this regard. Herein, the MCC was synthesized from jute fiber by a facile ammonium persulfate (APS) oxidation method resulting in carboxylic functional groups on the fiber surface. The carboxylated MCC was utilized to develop polyvinyl alcohol (PVA) composite films in a solution casting method. The surface chemistry, thermal properties, and surface morphology of MCC and MCC-PVA composite films were studied by FT-IR spectroscopy, thermogravimetric analysis, and scanning electron microscopy. The SEM images confirmed the rod-like MCC with average particle diameter 4.6 μm and length in 48.4 μm. The FT-IR spectroscopy suggested the complete removal of lignin and hemicellulose from jute fiber. A peak at 1730 cm−1 was introduced in MCC due to oxidation with APS. The MCC was readily dispersible in water, and chemical interaction with –OH group of PVA was spontaneous due to the carboxylation in MCC. The absorption peak of –OH groups in MCC-PVA composite films were shifted, somewhat disappeared and weakened due to the intra and intermolecular hydrogen bonding of MCC and OH groups in PVA. Thermogravimetric analysis expressed the thermal behavior of MCC and MCC-PVA composite films. The char formation at 500°C of the two different composite films was 15% and 16%, respectively. The stability of MCC-PVA composite films at elevated temperatures is the indication of potential application as flame retardant material.

Oil palm empty fruit bunch cellulose fillers as alternative fillers for carboxylated nitrile butadiene rubber latex films

Malaysia is one of the largest contributors to oil palm plantations and industries, resulting in the generation of a lot of oil palm waste such as oil palm empty fruit bunch (OPEFB). The main goal of this research is to investigate the effect of the OPEFB cellulose as one of the alternative fillers in the carboxylated nitrile butadiene rubber (XNBR) latex films. The OPEFB waste was subjected to ultrasonic with alkali and bleaching treatment prior to addition in XNBR latex compounds. The ultrasonic treatment shows better removal of wax, hemicellulose and lignin but leads to breaking down the crystalline structure of the cellulose particles resulted in reduction of the mechanical properties of the OPEFB cellulose filled XNBR latex films. The OPEFB cellulose filled XNBR latex compound is then subjected to different zinc oxide (ZnO) loading. It found that the increase in zinc oxide loading enhanced the ionic crosslink formation but disrupt the covalent crosslink formation since most of the metal cations Zn2+ tend to form ionic clusters for the ionic crosslinks and Zn-cellulose complex. Overall, the OPEFB cellulose fillers shows positive impact as alternative fillers in XNBR latex films.

Effect of mercerization on the chemical characteristics of plant-based natural fibers

In this study,the microstructure and chemical characterization of untreated and alkaline treated plant-basednatural fibers such as pineapple, kenaf, flax, hemp were performed. The objective of the present work is to understand the effectiveness of mercerization on the characteristics of plant-based natural fibers. First, the raw untreated fibers was subjected to treatment in 5% NaOH solution for the removal of surface impurities and thereby enhancing the hydrophobic nature of fibers. After NaOH treatment, the fibers were washed 3–4 times with distilled to remove the sodium hydroxide settlements during mercerization. The microstructure analysis of the untreated and treated fibers was performed using the Field Emission Scanning Electron Microscope (FESEM). Moreover, the elemental composition was studied using the Energy Dispersive X-ray Spectroscopy (EDS).Results from the FESEM analyses revealed that the alkaline treatment of raw fibers using NaOH helped in the removal of surface impurities, lignin, and hemicellulose. Moreover, the elemental composition obtained from EDS analysis showed an increased amount of carbon content in untreated fibers.