Delignification Ratio Research Articles

Facilitating the fabrication of diverse bio-based nanomaterials from bamboo using one-pot hydrated deep eutectic solvent pretreatment

The conversion of biomass feedstocks into bio-based nanomaterials was made easier with hydrated DES (HDES) pretreatment, which can boost the value-added applications of lignocellulosic biomass. In this study, two types of HDESs were initially prepared by 3-Chloro-2-hydroxypropyltrimethyl ammonium chloride (CHPTAC) with formic acid (FA) and acetic acid (AA), respectively. We achieved rapid conversion of bamboo feedstock into bio-based nanomaterials (including lignin nanoparticles, LNPs; lignin-containing cellulose nanofibers, LCNFs) through one-pot microwave-assisted HDES pretreatment coupled with robust nanofabrication strategies. The findings demonstrated that an impressive delignification ratio of 92.10 % and a cellulose retention ratio of 92.95 % were achieved under the optimal DES pretreatment conditions (120 °C, 20 min). The fractionated lignin fractions were effortlessly self-assembled into dispersed, uniformly shaped circular LNPs (<100 nm) using a novel proposed strategy, which was successfully applied to stabilizing oil-in-water (O/W) Pickering emulsions. To produce LCNFs, we conducted functionalization of cellulose-rich residue in aqueous citric acid followed by simple ultrasonic treatment. Compared to the control LCNF, the LCNF-based self-assembly films exhibited significantly improved mechanical properties and hydrophobicity (water contact angle 106.26°). In short, the proposed HDES pretreatment combined with robust nanofabrication strategies will broaden the fractionation and fabrication of bio-based nanomaterials, enhancing their potential in promising fields.

Effect of Treatment Time on Deep Eutectic Solvent Treatment of Scots Pine Wood

Aim of study: The influence of the treatment time (1 hour, 2 hours, and 3 hours) on the deep eutectic solvent (DES) treatment of Scots pine (Pinus sylvestris L.) wood is investigated in this study. &#x0D; Area of the study: Determination of DES performance on the Scots pine wood chemical structure.&#x0D; Material and methods: Choline chloride (ChCl) and lactic acid (LA) mixture with molar ratio of 1:10 (w:w) was used as a DES solvent. Treatments were carried out in an autoclave at 121 °C. The effects of DES treatment on the properties of wood and lignin samples of Scots pine were determined according to the relevant standards.&#x0D; Main results: The delignification ratio, lignin purity, and lignin yield in the 3h-treated sample were determined to be 79.78%, 86.43%, and 82.48%, respectively. The crystallinity index (CrI) was increased from 55.87% to 71.58% with 3 h DES treatment. Brunauer-Emmett-Teller (BET) analysis results showed that the surface area of the sample increased with 3-h DES treatment (from 3.095 m2/g to 3.621 m2/g). The 1-hour DES-treated sample yielded the lightest colored lignin (L*: 71.62). &#x0D; Research highlights: Treatment time of Scots pine wood during DES treatment has a significant effect on the wood and lignin properties

Pulp and Paper Properties of Jenitri Wood (Elaeocarpus ganitrus)

Jenitri trees are widely distributed in community forests on Java Island and their wood is utilized for various products. The objective of the study was to assess the basic properties and quality of pulp and paper from jenitri wood. The tree was felled at the age of 5, and the base part was taken. Chips were processed using three different pulping methods in soda (17% NaOH), kraft (17% NaOH and 25% sulfidity), and neutral sulfite semi-chemical (NSSC) (12% Na2SO3 and 3% Na2CO3) processes. The fibers of jenitri had good derived values (slenderness, Runkel, and flexibility ratios) as well as chemical properties. The screened yields from the soda, kraft, and NSSC processes were 35.60 ± 4.75%, 35.05 ± 3.83%, and 46.29 ± 2.59%, respectively. The kappa numbers from the soda, kraft, and NSSC processes were 28.02 ± 7.35, 21.15 ± 1.61, and 71.28 ± 6.86, respectively. The handsheets had a burst index value of 0.65–2.94 kPa.m2/g, a tear index value of 5.23–5.47 mN.m2/g, a tensile index value of 15.13–30.49 Nm/g, a brightness value of 24.39–45.25%, and an opacity value of 98.83–99.68%. The soda pulp and the kraft pulp had slight differences in all parameters except for the Kappa number. The NSSC pulp showed slight differences in the selectivity of delignification ratio, tear index, and opacity, but produced a higher brightness level compared to chemical pulpings. The values of burst and tear indices for kraft pulp paper met the Indonesian National Standard for leaf bleached kraft pulp.

Cascade fractionation of bamboo shoot shells into high-yield xylose, easily digestible cellulose and high-quality lignin nanoparticles by tailored catalytic hydrothermal–hydrated alkaline deep eutectic solvents pretreatment

The high complexity and compactness of inherent structure in lignocellulosic materials (LCM) leads to the difficulty of fractionation and conversion of its major component, which is the key obstacle limiting the value-added utilization of LCM. In this work, a cascade fractionation strategy, coupling catalytic hydrothermal pretreatment (CHTP, choline chloride: ethylene glycol: AlCl3, ChCl/ EG/ AlCl3) with hydrated alkaline deep eutectic solvent (HADES, triethylbenzyl ammonium chloride/ethanolamine, TEBAC/EM) treatment, was proposed to fractionate dendrocalamus latiftorus munro shoot shells (DLMSS). The results showed that considerably high hemicelluloses removal (94.57 %) and xylose yield (90.73 %) were achieved by the first step (CHTP, 160 °C, 1 h, 2 % of catalyst loading). The cascaded HADES treatment realized 90.25 % delignification ratio under the optimal conditions (120 °C, 3 h, 75 % of ADES loading), and the obtained residue could be easily converted into high-yield (93.35 %) of glucose via enzymatic saccharification. In addition, multiple enrichment cycle strategy (MECS) was performed to facilitate the recyclability of the HADES. The results showed that the enriched lignin recovered by MECS was activated by in-situ demethoxylation reaction. And such lignin fraction could be easily assembled into homogeneous lignin nanoparticles (LNPs, ∼31.51 nm in diameter) by simple sonication. Meanwhile, the MECS signally energized the antioxidant activity of the enriched lignin. Based on the high-efficiency cascade fractionation with the coupled CHTP-HADES fractionation strategy, it will observably boost the effectiveness and scalability of the advanced biorefinery strategy.

Green Fractionation and Structural Characterization of Lignin Nanoparticles via Carboxylic-Acid-Based Deep Eutectic Solvent (DES) Pretreatment

Green fractionation and a comprehensive overview of lignin molecular structures during the DES (deep eutectic solvent) pretreatment are very important for lignin valorization and the whole biorefinery process. Herein, intractable woody biomass (poplar wood) was pretreated with five types of carboxylic-acid-based DESs (acetamide served as an HBA (hydrogen bond acceptor), propanedioic acid, tartaric acid, malic acid, glutaric acid, and succinic acid served as HBDs (hydrogen bond donors)) under the optimized pretreatment conditions. Results showed that the optimal delignification ratio was achieved for tartaric-acid-based DES at 140 °C for 20 min under microwave-assisted heating. Two-dimensional HSQC NMR data demonstrated that the isolated poplar DES lignin consisted mainly of β-β, β-O-4 (normal and acylated forms), β-5, and esterified p-hydroxybenzoates (PBs) in different contents. Especially, the contents of β-O-4 in the isolated DES lignin fractions varied based on the pretreatment temperature and different chemical compositions of the DES. The antioxidant activity (2,2-diphenyl-1-picrylhydrazyl, DPPH analysis), microstructure (scanning electron microscope, SEM), and molecular weights (gel permeation chromatography, GPC) of the DES lignin fractions demonstrated that the DES delignification promoted the rapid assembly of lignin nanoparticles (LNPs) and could yield homogeneous lignin (1.23 &lt; PDI &lt; 1.58) with controlled nanometer size (30–170 nm) and good antioxidant activity. This study will improve the knowledge of structural changes of lignin during the different carboxylic-acid-based DES pretreatments and maximize the lignin valorization.

Complete valorization of bamboo biomass into multifunctional nanomaterials by reactive deep eutectic solvent pretreatment: Towards a waste-free biorefinery

The introduction of nanotechnology into conventional biorefinery will facilitate complete valorization of lignocellulosic biomass. In this work, a microwave-assisted deep eutectic solvent (DES) pretreatment was developed for one-pot fractionation of bamboo biomass into three scalable fractions (cellulose-rich residue, lignin and recovered DES), which were then respectively upgraded to three value-added bio-based nanomaterials, namely lignin-containing cellulose nanofibrils (LCNFs), lignin nanoparticles (LNPs) and carbon quantum dots (CDs). After the mild and rapid DES pretreatment (130 °C, 20 min), 51.0% cellulose-rich residue was recovered accompanied by 90.6% delignification ratio. The cellulose-rich residues were mechanically fibrillated into LCNFs with a width of 5–20 nm. In-situ esterification of carboxylic acid groups from DES with cellulose hydroxyl groups improved the hydrophobicity of LCNFs. The LCNFs film prepared exhibited excellent hydrophobic (water contact angle of 103.3°). In-situ esterification, condensation and cleavage reactions of lignin during DES fractionation enhanced its amphiphilicity and facilitated lignin self-assembly into LNPs with diameters of 30–75 nm. Furthermore, using the recovered DES as carbon precursors, CDs were successfully prepared by a typical hydrothermal method, which provides a new approach for the disposal of waste DES. In short, the proposed waste-free biorefinery scheme realizes the complete valorization of bamboo biomass into bio-based multifunctional nanomaterials, which can be further applied in various downstream fields.

The effect of delignification ratio on the PMMA occupation in poplar wood cell wall by the macro and micro comparative study

The polymer/wood functional products may not be true nanocomposites due to the poor permeability of non-polar monomers into the hydrophilic wood cell wall. In this paper, methyl methacrylate (MMA) chosen as the representative non-polar monomer was used to impregnate wood with different lignin removal and then polymerized in situ in delignified wood to obtain polymethyl methacrylate/delignified wood (PMMA/DW). The larger 10 nm mesopores reduction in PMMA/DW-29.9 and the disappearance of the smaller 3 nm mesopores of PMMA/DW-51.7 indicated that the removal of lignin was beneficial for the penetration of MMA in the wood cell wall. When the lignin removal reached between 29.9 and 51.7%, the dimensional stability of PMMA/DW was improved, and it could be speculated that the resin began to enter the wood cell wall at this stage. In addition, the indentation modulus and hardness of the PMMA/DW cell wall were significantly increased when the lignin removal reached 29.9%. This result was consistent with the conclusion of the pore size analysis, which further confirmed that the nanopores of the cell wall were filled with PMMA when the lignin removal was greater than 29.9%. The results of this paper indeed provide a basis for the design of biomass functional nanocomposites.

Using nucleophilic naphthol derivatives to suppress biomass lignin repolymerization in fermentable sugar production

Dilute acid pretreatment of biomass decomposes hemicelluloses but cannot effectively remove lignin. Here we investigate the adding of add five nucleophilic derivatives including 2-naphthol, 6-hydroxy-2-naphthoic acid (6H2NA), 2-hydroxy-1-naphthoic acid (2H1NA), 6-hydroxy-1-naphthoic acid (6H1NA), and 3-hydroxylic-2-naphthoic acid (3H2NA) to enhance the efficiency of lignin removal. The 72-h hydrolysis yield of pretreated substrates was increased from 30.9% to 34.7%, 38.3%, 36.0%, 36.0%, and 53.2%, respectively. The chemical composition, cellulose accessibility, and surface chemistry of pretreated materials with or without additives showed the improved hydrolysis yield with 3H2NA addition being related to lower surface lignin content, higher cellulose accessibility, and delignification ratio. Furthermore, the analysis of HSQC and 31P NMR spectra of the residual lignin reflects the influence of naphthol derivatives on lignin structure. The results showed that the 3H2NA additive increased the content of lignin carboxyl groups and enhanced the helping fractionation and suppression of lignin repolymerization. These improvements through 3H2NA addition reduce lignin inhibition of fermentable sugar production from pretreated biomass.

The effects of mild Lewis acids-catalyzed ethanol pretreatment on the structural variations of lignin and cellulose conversion in balsa wood

Ethanol organosolv pretreatment is a green and effective deconstruction process for main components in lignocellulose biomass. Herein, balsa wood was firstly subjected to a modified ethanol/water solution (EWS) pretreatment with different Lewis acids catalysts (AlCl3, CuCl2, FeCl3) at 140–180 °C. The delignification ratios and structural characteristics of the dissociated lignin, enzymatic hydrolysis of cellulose in the pretreated substrates as well as the degradation products from hemicellulose during the pretreatment process were comprehensively investigated. Results showed that dissociation and depolymerization of lignin fragments was robust in AlCl3-catalyzed pretreatment than those by CuCl2 and FeCl3-catalyzed pretreatment. In detail, the results showed that the optimal delignification ratio and removal of the hemicelluloses occurred in AlCl3-catalyzed pretreatment. Moreover, the structural characterizations of lignin fractions by 2D-HSQC, 31P NMR and GPC also revealed that the obtained lignin has the advantages of small and homogeneous molecules as well as abundant functional groups. As a result of adequate removal of hemicellulose and lignin, the enzymatic digestibility of cellulose in the pretreated residue was significantly elevated. In short, the above findings are also in line with the concept of maximizing the utilization of bioresources, which will be beneficial for value-added applications of balsa wood in the biorefinery.

Effect of ascorbic acid assisted dilute acid pretreatment on lignin removal and enzyme digestibility of agricultural residues

Efficient pretreatment for lignocellulosic biomass is crucial in developing a viable biorefinery process. An ascorbic acid (AsA)-assisted dilute acid pretreatment strategy was developed to improve enzymatic hydrolysis efficiency. In this study, the effect of ascorbic acid addition on the dilute acid pretreatment of wheat straw (WS), corn stover (CS), and corncob (CC) was assessed and compared. The 72 h hydrolysis yield was improved by 12.47, 18.78, and 13.57% in dilute acid pretreated WS, CS, and CC with ascorbic acid addition, respectively. In addition, the cellulose accessibility, enzyme adsorption, chemical composition analysis, and structural features of pretreated biomass with ascorbic acid were determined to better understand its mechanistic effect on enzymatic hydrolysis. The results indicated that the addition of ascorbic acid in the dilute acid pretreatment reduced surface lignin content and enhanced cellulose accessibility, delignification ratio, and enzyme adsorption ability.

P-39 木材の脱リグニン率とイオン液体への溶解性の相関(CNF・リグニン,ポスター発表)

P-39 木材の脱リグニン率とイオン液体への溶解性の相関(CNF・リグニン,ポスター発表)

바이오에탄올 생산을 위한 폐MDF의 전처리 및 효소 당화

The objective of this study was designed to determine the possibility of bioethanol production from wasted medium density fiberboard (wMDF). We were investigated the enzymatic saccharification characteristics using the enzyme (Cellic CTec3) after pretreatment with sodium chlorite. According to the component analysis results, the lignin contents before and after the pretreatment of wMDF (milling using sieve size of <TEX>$1,000{\mu}m$</TEX>) was significantly reduced from 31.13% to 4.11%. Therefore, delignification ratio of pretreated wMDF was found to be up to about 87-89% depending on the sieve size. And we were tested to compare the saccharification ratio according to the sieve size of wMDF (<TEX>$1,000{\mu}m$</TEX>, <TEX>$200{\mu}m$</TEX>), but it was no significance depending on the sieve size. When enzyme dosage was 5% based on the substrate concentration, enzymatic saccharification ratio was obtained up to 70% by maintaining at <TEX>$50^{\circ}C$</TEX> for 72 hours. We could made the substrate concentration of pretreated wMDF (<TEX>$1,000{\mu}m$</TEX>) up to 12% and then enzymatic saccharification ratio was 76.8%, also contents of glucose and xylose were analyzed to 77,750 and 14,637 mg/L, respectively.

Evaluation of different lignocellulosic raw materials as potential alternative feedstocks in biorefinery processes

In the present work several alternative lignocellulosic materials have been classified according to their type and origin, and chemically characterized in order to propose their proper exploitation as biorefinery feedstock. In addition, different fractionation processes have been applied to some of these raw materials with the purpose of evaluating their efficiency and applicability for different feedstocks. The yield of each applied treatment has been determined according to the delignification ratio and the carbohydrate dissolution degree achieved. The characterisation results indicated that different lignocellulosic feedstocks could be treated together in biorefinery processes because of similar compositions and fractionation behaviour. Furthermore, different pretreatments could be applied for the achievement of specific fractionation results, depending on the desired solid or liquid by-product to obtain.

High-Consistency Electrochemical Delignification of Poplar Kraft Pulp

The electrochemically mediated delignification of pulp fibers is one of the promising bleaching methods, which can give the delignified pulp with good subsequent bleachability and high pulp viscosity. Our previous work has shown that the poplar kraft pulp can be delignified to 45% delignification ratio with less than 10% pulp viscosity loss at the condition of 1% pulp consistency which limits the application of this method in pulp industry. The high-consistency electrochemical delignification of poplar kraft pulp was investigated in this paper. The delignification ratio, pulp viscosity loss and brightness were measured as well as the delignification conditions, such as pulp consistency, voltage of electrolysis cell, temperature, circulation of electrolysis liquor and time, were discussed. The results showed that at the 10% pulp consistency, the circulation of electrolysis liquor between pulp cell and electrolysis cell can efficiently improve the delignification ratio, and the pulp viscosity loss is less than 10%. The subsequent bleachability for H2O2 is similar as that of 1% consistency delignified pulp. The pulp also can be bleached to higher than 80% ISO with following EP stage at 2.5% H2O2 dosage.

Sodium carbonate–sodium sulfite pretreatment for improving the enzymatic hydrolysis of rice straw

The performance of sodium carbonate–sodium sulfite (Na2CO3–Na2SO3) pretreatment on improving the enzymatic hydrolysis of rice straw was investigated. The results indicated that both Na2CO3 and Na2SO3 pretreatments are effective in improving the enzymatic digestibility of rice straw. A higher ratio of Na2SO3 in pretreatment liquor performed better at softening the rice straw through degradation of hemicellulose, delignification, and lignin sulfonation, while it was conserving more polysaccharides during the pretreatment than Na2CO3. The highest sugar recovery of pretreated rice straw, 74.5%, 82.7%, and 59.5% for total sugar, glucan, and xylan, respectively, was obtained at cellulase loading of 20FPU/g-cellulose after the pretreatment at 140°C, chemical charge of 12%, Na2CO3–Na2SO3 ratio of 0:1 (i.e., only Na2SO3 pretreatment). The corresponding delignification ratio of pretreated solid was 53.4%, and 91.4% of the polysaccharides were conserved. The sugar recovery of only Na2CO3 pretreatment at the ratio of 1:0 was 67.1%, 74.4%, and 53.7% for total sugar, glucan, and xylan, respectively, at 140°C, chemical charge of 12%, and enzyme loading of 20FPU/g-cellulose. Its corresponding delignification ratio was 40.3%, and polysaccharides conservation ratio was 88.9%.

Effects of sodium carbonate pretreatment on the chemical compositions and enzymatic saccharification of rice straw

The effects of sodium carbonate (Na2CO3) pretreatment on the chemical compositions and enzymatic saccharification of rice straw were investigated. The enzymatic digestibility of rice straw is enhanced after pretreatment since pretreated solids show significant delignification with high sugar availability. During pretreatment, an increasing temperature and Na2CO3 charge leads to enhanced delignification, whereas an increased degradation of polysaccharides as well, of which xylan acts more susceptible than glucan. The sugar recovery of enzymatic hydrolysis goes up rapidly with the total titratable alkali (TTA) increasing from 0% to 8%, and then it reaches a plateau. The highest sugar recovery of rice straw after pretreatment, 71.7%, 73.2%, and 76.1% for total sugar, glucan, and xylan, respectively, is obtained at 140°C, TTA 8% and cellulase loading of 20FPU/g-cellulose. In this condition, the corresponding delignification ratio of pretreated solid is 41.8%, while 95% of glucan and 76% of xylan are conserved.

Ultrasound Assisted Lime Pretreatment of Lignocellulosic Biomass toward Bioethanol Production

The present study acquaints optimization of ultrasound assisted lime pretreatment to reduce the time of lime pretreatment. The study was conducted on three lignocellulosic biomass materials, Areca nut husk (Areca catechu), bon bogori (Ziziphus rugosa), and moj (Albizia lucida) available in Northeast India, exploiting ultrasound for the pretreatment of lignocellulosic biomass along with lime augments the delignification ratio. The present study reports removal of 68% (bon bogori), 65% (Areca nut husk), and 64% (moj) of the lignin present in the naive lignocellulosic fiber with good recovery of total solid and fermentable sugars, respectively. The simultaneous saccharification and fermentation (SSF) process for the production of bioethanol was also carried out using baker’s yeast. The yield of ethanol was found to be in the range from 0.32 to 0.43 for all the ultrasound assisted lime pretreated biomasses.

Influence of plum gum and sodium perborate addition on spruce kraft pulp properties during oxygen delignification

The aim of this study was to investigate the effects of plum gum liquor and sodium perborate addition to oxygen delignification process on spruce kraft pulp properties. Yields and viscosity of pulp were protected against oxidative attack, when kappa number of pulp was not changed by adding plum gum to oxygen delignification process. Delignification ratio improved by 7.4% without any viscosity loss by adding only 0.25% sodium perborate as active oxygen with plum gum liquor to the oxygen delignification process. It was found that crystallinity of pulp was improved by adding plum gum and sodium perborate to oxygen delignification. It was also determined that sodium perborate had an affirmative effect on delignification ratio, when plum gum affected pulp viscosity positively.

Effect of ethyl acetate on carbohydrate components and crystalline structure of pulp produced in aqueous acetic acid pulping

AbstractThe aim of this study was to investigate the changes in carbohydrate components and the crystalline structure in hemp bast fibers by adding ethyl acetate to acetic acid/water pulping processes. It was found that ethyl acetate added to acetic acid/water process had a positive effect on yield, viscosity and carbohydrate components in pulp. It was assumed that the delignification ratio increased by adding ethyl acetate to aqueous acetic acid pulping. Xylose content in hemp bast fibers was affected more negatively in the ethyl acetate/acetic acid/water process than in the acetic acid/water one. Crystallinity and crystallite size were higher in pulp sample obtained by the acetic acid/water process without ethyl acetate.

Effect of anthraquinone on brightness value and crystalline structure of pulp during soda processes

AbstractThe dependence of crystalline structure and optical properties of pulp on anthraquinone (AQ) added to the soda process at different cooking times was determined in this study. Wheat (Triticum aestevum L.) straw was used as the raw material for pulp. Soda and soda-AQ processes were selected for pulping at 80 min and 120 min. The soda-AQ process improved the yield and viscosity of pulp delignification ratio for pulping in comparison with the soda process. Crystallinity of pulp samples decreased by adding anthraquinone to the soda process because of stabilized less ordered cellulose and amorphous hemicelluloses in pulp. It was determined that crystallinity of pulp samples decreased with longer cooking time, from 80 min to 120 min, in both soda and soda-AQ processes. Monoclinic structure was dominant in pulp samples; however, the triclinic structure ratio increased in both soda and soda-AQ processes compared to raw material. It was found that brightness and lightness values in pulp samples decreased when using anthraquinone depending on the changes of the crystalline structure.