Delignification Rate Research Articles

Microscopic mechanism investigation of extraction of lignin by benzyltriethylammonium chloride-based deep eutectic solvents

Benzyltriethylammonium chloride (BTEAC)-based deep eutectic solvent (DES) has a high delignification rate in the pretreatment of lignocellulose, and the lignin obtained from the removal has the advantages of high purity and low molecular weight. The interaction mechanism between BTEAC-based DES and lignin at molecular level was investigated by multiscale simulation analytical approach. By analyzing the types of weak interaction, charge distribution, number of hydrogen bonds, energy distribution and density distribution in different systems, the influence of six hydrogen bond donor (HBD) structures on the extraction process was clarified. The interaction between Cl- and lignin is mainly electrostatic interaction, and the interaction between BTEA+ and lignin is mainly van der Waals (vdW) interaction. The original π-π stacking of lignin is replaced by the new π-π stacking between BTEA+ and lignin. The effects of different functional groups and length of carbon chain on the interaction were researched. The acidic HBD with short carbon chain has a larger interaction and can affect the ether bond on the lignin. Among them, due to the smaller volume of formic acid (FA), it provides more space for BTEA+ to contact with lignin, resulting in stronger interaction. The molecular-level theoretical foundation underpinning the efficacy of BTEAC-FA in lignin removal during the pretreatment process is provided.

Optimization and characterization of a biphasic solvent system for vinegar residue pretreatment: Enhanced fractionation efficiency, propionic acid production, and sustainability

This study introduces a novel biphasic solvent system composed of phenoxyethanol and p-Toluenesulfonic acid (p-TsOH) for the pretreatment of vinegar residue (VR). The system achieves high cellulose retention (80.15 %) and effective removal of hemicellulose (97.10 %) and lignin (88.31 %) under mild conditions (127°C, 1.9 h). Structural changes in pretreated VR were analyzed, revealing significant improvements in enzymatic hydrolysis yield, achieving nearly 90 % conversion.The hydrolysate supports fermentation by Acidpropionibacterium jensenii, leading to efficient propionic acid production. The sugar-to-acid conversion rate of 28.15 % highlights the hydrolysate’s quality for lignocellulosic biotransformation. Density functional theory and molecular dynamics simulations confirm stable lignin interactions in the system, driven by hydrogen bonding, van der Waals forces, and π-π stacking, which promote lignin removal. Recycling phenoxyethanol over four cycles maintains high cellulose digestibility (84–95 %) and consistent delignification rates (88–89 %). The mass balance validated the efficient fractionation of biomass. A comprehensive analysis was conducted on the sustainability, safety, and environmental impact of the system. In conclusion, this study presents a novel biphasic solvent system that effectively fractions biomass, enhances solvent recovery, and reduces environmental impact. This system demonstrates broad applicability to different lignocellulosic biomasses, contributing to both economic and ecological sustainability.

Cold plasma/alkaline pretreatment facilitates corn stalk fractionation and valorization towards zero-waste approach

The present study employed alkaline hydrogen peroxide pretreatment coupled with cold plasma for corn stalk’s complex biopolymers fractionation and valorization through enzymatic hydrolysis. This hurdle approach enables the prolonged generation of reactive oxidative species, initiating chemical reactions otherwise hardly possible under ambient conditions. A delignification rate between 76±1 and 86±2 % was obtained under different process parameters in a significantly shorter time compared to conventional alkaline pretreatment. Up to 94±4 % of cellulose in treated biomass was converted to glucose after enzymatic hydrolysis, achieving around 3.5 times higher glucose yield than the raw biomass. Different spectroscopic analyses confirmed specific alterations in the structure of the lignin-rich fraction caused by cold plasma. Micro- and nanoscale lignin particles obtained were rich in total phenolic content, reaching up to 140±20 and 107±12 µg gallic acid equivalents (GAE) per mg of lignin, respectively. The proposed concept of corn stalk fractionation through biorefinery can open new opportunities for valorizing different agricultural waste types.

Highly uncondensed lignin extraction in the novel green L-cysteine/lactic acid cosolvent system

Enhancing the efficient isolation of proto-lignin from lignocellulose using sustainable, environmentally friendly solvents has consistently been a key focus in the lignin-first biorefinery strategy for the past years. At the same time, achieving efficient extraction of highly uncondensed active lignin under acidic conditions has posed an insurmountable challenge. In this study, we develop an L-cysteine-assisted binary acidic cosolvent that efficiently separates the uncondensed lignin under 80 ∼ 90 °C treatment, resulting in a lighter color and a recovery yield of up to 60 %. The corresponding delignification rate reached 82.6 %. The obtained lignin exhibited an ideal retention rate (maximum 84.5 %) of alkyl aryl ether bonds (β–O–4) relative to the native lignin in raw material. The resulting residue was free from cellulose decomposition and yielded over 90 % cellulose with a surface-esterified structure. This study establishes a one-step L-cysteine-assisted stabilization methodology that overcomes the challenges of lignin condensation and allows for the fractionation of lignocellulose into highly uncondensed lignin and high-quality cellulose, thus offering new solutions for biorefinery.

A coupling strategy combined with acid-hydrothermal and novel DES pretreatment: Enhancing biomethane yield under solid-state anaerobic digestion and efficiently producing xylo-oligosaccharides and recovered lignin from poplar waste

Lignocellulose is an abundant renewable bio-macromolecular complex, which can be used to produce biomethane and other high-value products. The lignin, presents in lignocellulose is typically regarded as an inhibitor of anaerobic digestion. Therefore, it is crucial to develop a novel selective separation strategy to achieve efficient biomethane production and all-component utilization of biomass. Hence, a combination of two-step pretreatment and solid-state anaerobic digestion was employed to enhance the production of biomethane and to generate valuable chemicals from poplar waste. Optimal conditions (4 % acetic acid, 170 °C, and 40 min) resulted in 70.85 % xylan removal, yielding 50.28 % xylo-oligosaccharides. The effect of a strong acid 4-CSA-based novel three-constituent DES on delignification was investigated from 80 °C to 100 °C; the cellulose content of DES pretreated poplar increased from 64.11 % to 80.92 %, and the delignification rate increased from 49.0 % to 90.4 %. However, high delignification of the pretreated poplar (DES-100 and DES-110) led to a rapid accumulation of volatile organic acids during the hydrolysis and acidogenesis stages, resulting in methanogenesis inhibition. The highest biomethane yield of 208 L/kg VS was achieved with DES-80 (49.0 % delignification), representing a 148 % improvement compared over untreated poplar. This approach demonstrates the potential for comprehensive utilization of all components of biomass waste.

Data-driven modeling and multi-objective optimization of a continuous kraft pulping digester

Understanding wood characteristics is essential for enhancing the economic sustainability of the kraft process. In a recent work, we included wood characteristics in the phenomenological modeling of digesters. The developed model allows the optimization of the process. Here, we propose a constrained multi-objective optimization approach to minimize the residual lignin content while maximizing the carbohydrate content in the cellulose pulp, using the Non-dominated Sorting Genetic Algorithm II. In order to reduce computational costs during the optimization, we developed a surrogate model, based on simulated data, to predict key performance indicators. We evaluated two machine learning techniques: Multilayer Perceptron (MLP) and decision tree-based methods, considering single and multiple outputs. The combination between the multiple-output approach and MLP performed well and resulted in a more simplified surrogate model. The results for the simulation and the surrogate model were similar, and the computational cost was approximately 50 times lower for the surrogate model. An uncertainty was associated with the multiplicative factor of the delignification rate as a way to observe how its estimate interferes with the Pareto curve. The present work presents contributions to data-driven modeling and multi-objective optimization of digesters, allowing us to determine the importance of wood characteristics in operation.

Fully upgrade bamboo biomass into three multifunctional products through biphasic γ-valerolactone and aqueous phosphoric acid pretreatment

In this manuscript, three components of lignocellulosic biomass were obtained by deconstructing bamboo with γ-valerolactone-H2O biphasic system, and the delignification rate of 80.92 % was achieved at 120 °C for 90 min. Lignin nanospheres with diameters ranging from 75 nm to 2 um could be customized by varying the self-assembly rate. Furthermore, the lignin nanospheres-poly(vinyl alcohol) film was prepared by cross-linking lignin nanospheres and poly(vinyl alcohol), which can obtain 90 % ultraviolet absorption capacity, while the light transmittance in non-ultraviolet band was almost unchanged. At the same time, due to the strong hydrogen formation between lignin nanospheres and poly(vinyl alcohol) bond network, the tensile properties of the composite film were also improved by 30 %. Besides, the high specific surface area of biomass-derived porous biochar (2056 m2/g) can be obtained after carbonization of solid residues at 850 °C for 2 h, which was almost 8 times the specific surface area of the direct biomass carbonization due to the removal of lignin and hemicellulose. biomass-derived porous biochar can be used as an adsorbent, with a CO2 capture capacity of 4.5 mmol g−1 at normal temperature (25 °C, 1 bar). The filtrate after the reaction contained a large amount of hemicellulose oligomers, which can be reacted with dichloromethane at 170 °C for 1 h to obtain the furfural yield of 74 %. In summary, the proposed biorefinery scheme achieves a full-component upgrade of lignocellulose and can be further applied in various downstream fields.

Evaluation of OxiOrganosolv pretreated hardwood and softwood lignocelluloses as substrates for the chemoenzymatic production of 5-hydroxymethylfurfural (HMF)

Furans, such as 5-hydroxymethylfurfural (HMF), are compounds of great importance that can serve as starting materials for the synthesis of polymers. Their production from lignocellulose-derived sugar streams offers a promising alternative to fossil fuels, while enabling biomass transformation to chemicals with higher value. In the present work, the production of HMF from OxiOrganosolv pretreated beechwood and pine was assessed by integrating a three-step process of enzymatic saccharification and isomerization followed by catalytic dehydration. The use of isobutanol in the pretreatment solvent and the addition of polyoxometallates (POMs) as oxidative catalysts were evaluated. The results showed that isobutanol leads to high delignification rates for both beechwood and pine, yielding cellulose-rich pulps with high susceptibility to enzymatic hydrolysis and isomerization. A fructose production up to 51.2 and 53.4 g/g of pretreated material was achieved for beechwood and pine, respectively, corresponding to 14 and 11.3 g of HMF/g of pretreated material. Regarding the use of POMs, the commercially available phosphomolybdic acid (HPMO) and POMs modified with oxidation metals (Fe-PMO, Cu-PMO) were tested, verifying their beneficial effect to lignin depolymerization and the composition of the final pulp. Hydrolysates produced from HPMo and Cu-PMo-assisted OxiOrganosolv pretreatment were efficiently used for the production of HMF, while severe inhibition of the dehydration reaction was observed with the hydrolysates from Fe-PMo pretreated biomass due to the presence of residual metals. This is the first systematic report comparing two lignocellulosic materials subjected to different pretreatment conditions for their potential to produce fructose and, subsequently, HMF.

Rapid fractionation of corn stover by microwave-assisted protic ionic liquid [TEA][HSO4] for fermentative acetone–butanol–ethanol production

BackgroundThe use of ionic liquids (ILs) to fractionate lignocelluloses for various bio-based chemicals productions is in the ascendant. On this basis, the protic ILs consisting of triethylammonium hydrogen sulfate ([TEA][HSO4]) possessed great promise due to the low price, low pollution, and high efficiency. In this study, the microwave-assistant [TEA][HSO4] fractionation process was established for corn stover fractionation, so as to facilitate the monomeric sugars production and supported the downstream acetone–butanol–ethanol (ABE) fermentation.ResultsThe assistance of microwave irradiation could obviously shorten the fractionation period of corn stover. Under the optimized condition (190 W for 3 min), high xylan removal (93.17 ± 0.63%) and delignification rate (72.90 ± 0.81%) were realized. The mechanisms for the promotion effect of the microwave to the protic ILs fractionation process were ascribed to the synergistic effect of the IL and microwaves to the depolymerization of lignocellulose through the ionic conduction, which can be clarified by the characterization of the pulps and the isolated lignin specimens. Downstream valorization of the fractionated pulps into ABE productions was also investigated. The [TEA][HSO4] free corn stover hydrolysate was capable of producing 12.58 g L−1 of ABE from overall 38.20 g L−1 of monomeric sugars without detoxification and additional nutrients supplementation.ConclusionsThe assistance of microwave irradiation could significantly promote the corn stover fractionation by [TEA][HSO4]. Mass balance indicated that 8.1 g of ABE and 16.61 g of technical lignin can be generated from 100 g of raw corn stover based on the novel fractionation strategy.

Combination of microwave with acid deep eutectic solvent pretreatment for reed (Phragmites australis) fractionation

The cost-effective and low-carbon fractionation of lignocellulosic biomass will enhance the economic viability of bio-refining. To achieve efficient reed fractionation under favorable conditions, microwave-assisted choline chloride and p-toluene sulfonic acid (M-ChCl/p-TsOH) pretreatment was employed. The fractionation of reed components demonstrated higher effectiveness with M-ChCl/p-TsOH pretreatment compared to conventional DES pretreatment. Under M-ChCl/p-TsOH conditions, a high hemicellulose removal rate (∼90%) and delignification rate (∼65%) were achieved while achieving a saccharification rate of 88% during cellulase hydrolysis. Microwave assistance not only significantly reduced reaction time to less than 60 s but also enhanced the pretreatment efficacy. Furthermore, the obtained lignin products consisted of low-polymerization lignin (MW < 800 g/mol) and acid-soluble lignin, providing a solid foundation for subsequent high-value utilization of lignin. This study provides a promising strategy for the low carbon fractionation of reed using DES, aiming to simultaneously achieve efficient cellulose hydrolysis and obtain tractable lignin.

Investigation of Microwave Irradiation and Ethanol Pre-Treatment toward Bioproducts Fractionation from Oil Palm Empty Fruit Bunch

Lignocellulosic biomass (LCB), such as the oil palm empty fruit bunches (OPEFB), has emerged as one of the sustainable alternative renewable bioresources in retrieving valuable bioproducts, such as lignin, cellulose, and hemicellulose. The natural recalcitrance of LCB by the disarray of lignin is overcome through the combinative application of organosolv pre-treatment followed by microwave irradiation, which helps to break down LCB into its respective components. This physicochemical treatment process was conducted to evaluate the effect of ethanol solvent, microwave power, and microwave duration against delignification and the total sugar yield. The highest delignification rate was achieved, and the optimum level of total sugars was obtained, with the smallest amount of lignin left in the OPEFB sample at 0.57% and total sugars at 87.8 mg/L, respectively. This was observed for the OPEFB samples pre-treated with 55 vol% of ethanol subjected to a reaction time of 90 min and a microwave power of 520 W. Microwave irradiation functions were used to increase the temperature of the ethanol organic solvent, which in turn helped to break the protective lignin layer of OPEFB. On the other hand, the surface morphology supported this finding, where OPEFB samples pre-treated with 55 vol% of solvent subjected to similar microwave duration and power were observed to have higher opened and deepened surface structures. Consequently, higher thermal degradation can lead to more lignin being removed in order to expose and extract the total sugars. Therefore, it can be concluded that organosolv pre-treatment in combination with microwave irradiation can serve as a novel integrated method to optimize the total sugar yield synthesized from OPEFB.

Investigation of Microwave-Assisted Ethanol Pre-Treatment Towards Delignification Efficiency of Oil Palm Empty Fruit Bunch

Lignocellulosic biomass (LCB) such as the oil palm empty fruit bunches (OPEFB) has emerged as one of the sustainable alternative renewable bio-resources in retrieving the valuable bioproducts such as lignin, cellulose, and hemicellulose. The natural recalcitrance of LCB by the disarray of lignin is overcome through the combinative application of organosolv pre-treatment followed by microwave irradiation, which helps to break down LCB into its respective components. This physicochemical treatment process was conducted to evaluate the effect of ethanol solvent, microwave power and duration against delignification and the total sugars yield. The highest delignification rate was obtained with lowest amount of lignin left in OPEFB sample of 0.57% for samples pre-treated with ethanol, subjected to reaction time of 90 minutes and microwave power of 520 W. Microwave power functions to increase the temperature of the ethanol organic solvent utilized, which in turn helps break the protective lignin layer of OPEFB. On the other hand, the data on surface morphology supports this data finding, where OPEFB samples pre-treated with 55 vol% of solvent subjected to similar microwave duration and power is observed to have higher opened and deepened surface structure, in which higher thermal degradation lead to more lignin being removed in order to expose and extract the total sugars. Therefore, it can be concluded that ethanol pre-treatment in combination with microwave irradiation can serve as a novel integrated method to optimize the delignification process from OPEFB.

Sustainable vine shoots-to-ethanol valorisation by a sequential acid/organosolv pretreatment

In this study, a fractionation and valorisation scheme for vine shoots is proposed for biofuel and lignin production. This agricultural waste was fractionated by acid/organosolv sequential pretreatment. In the first step, acid pretreatment was optimised at 150ºC and 1.2% H2SO4 to release hemicellulosic sugars, of which 76% could be recovered. This sugar stream was co-fermented by E. coli with an ethanol yield higher than 98% after detoxification with resins or NH4OH. The solid obtained under optimal acid pretreatment conditions was delignified by organosolv treatment, and a delignification rate of 43% was reached at 180ºC. This substrate with 83% enzymatic digestibility was bio-converted into ethanol by simultaneous saccharification and fermentation, with a yield of 76%. Additionally, lignin was recovered from the organosolv liquor, aiming for the full valorisation of the biomass, which showed a syringyl/guaiacyl ratio of 0.92 by nuclear magnetic resonance, complying with the data provided for Fourier transform infrared spectroscopy and confirming the aromaticity of this fraction for further valorisation.

Lewis acid/base mediated deep eutectic solvents intensify lignocellulose fractionation to facilitate enzymatic hydrolysis and lignin nanosphere preparation

In this work, Lewis acids (FeCl3, AlCl3) and bases (Na2CO3, Na2SO3) were incorporated into a neutral deep eutectic solvent (DES, choline chloride/glycerin) to intensify the lignocellulose fractionation. The efficiency of fractionation in terms of the maximum delignification rate (89.7 %) and well-pleasing cellulose saccharification (100 %) could be achieved by the Lewis acid-mediated DES. An in-depth insight of the evolution of lignin structure revealed that Lewis acid-mediated DES could cleave the β-O-4 linkages efficiently to achieve a high yield lignin fragments. Meanwhile, the lignin fragments with the enhanced amphiphilic properties facilitate the preparation of lignin nanospheres (LNSs) via the self-assembly process. The resultant LNSs extracted by Lewis acid-mediated DES exhibited an excellent thermal stability, and enhanced antibacterial capacity, which were associated with the phenolic OH content. However, the extracted lignin by Lewis base-mediated DES was mainly attributed to the cleavage of lignin-carbohydrate complexes bond, especially the lignin-carbohydrate ester bond, which retained more ether bonds and a relatively complete structure. This study illuminated the different mechanisms of lignin extraction and the structural evolution of lignin from Lewis acid/base-mediated DES, and provided guidance to select suitable fractionation techniques for upgrading the downstream products.

Preparation of lignin-containing cellulose nanofibers from walnut shell using deep eutectic solvent for nanotube conductive film

A deep eutectic solvent (DES) was employed to purify cellulose by depolymerizing agricultural waste walnut shells (WS) at 90 ℃ from 1.5 to 3.0 h. The pretreatment achieved an 88.57% delignification rate and yielded 33.62% cellulose solids (CS), with 77.63% cellulose and 13.11% lignin contained in CS. The DES pretreatment exposed functional groups on the surface of cellulose and resulted in a 24.7% increase in crystallinity. Suspension with a homogeneous distribution of lignin-containing cellulose nanofibers (LCNF) was made by ultrasonic dispersing (650 W, 30 min), and the average length of 1406 nm, the ζ-potential of − 17.65 mV. Higher lignin content led to cross-linking effect which produced a heightened degree of entanglement of LCNF while increasing the UV-shielding property and thermal stability. Additionally, LCNF stabilized the dispersion of multi-walled carbon nanotubes (MWCNT) in water, and served as a carrier for MWCNT conductive networks, which showed a tensile strength of 63.86 MPa and a conductivity of 15.63 S/m. The composite film exhibited potential applications in real-time monitoring of pressure sensing.

Effect of ozone pretreatment of flax fiber processing waste under less water environment: Physicochemical property evaluation and digestibility metrics

Compared with the commonly used pretreatment such as organosolv, diluted acid/alkali, etc., gas phase pretreatment got the advantages of low water consumption, low reaction temperature/ time, and could degraded cellulose to smaller chains without much cellulose loss. Thus, this study pretreated flax fiber manufacturing processing waste (FFPW) with gas phase ozone for producing fermentable sugar. Experimental results showed that FFPW got about 32.5% lower lignin (13.0%) and 59.0% higher cellulose/hemicellulose ratio (3.66) compared with most of the commonly used lignocellulose materials; which make it suitable for fermentable sugar production. Gas phase pretreatment got 31.9% higher delignification rate than that under liquid phase. Under the optimal reaction condition (extra water content 79.7%, pH 3.2, ozone feed speed 101.4 mg/L/min, 21.8 min, room temperature), the FFPW get lignin content of 3.6%, cellulose content of 73.8%, digestibility of 96.1% (solid concentration 0.02 g/mL). Under high solid concentration hydrolysis (solid concentration 0.4 g/mL), ozone pretreated FFPW released 168.0 g/L glucose, which was about 10.0% higher than that of the commonly used lignocellulose materials.

Novel supramolecular deep eutectic solvent-enabled in-situ lignin protection for full valorization of all components of wheat straw

Lignin is usually deemed as an inhibitor to enzymatic hydrolysis of cellulose due to its physical barrier, non-productive adsorption, and steric hindrance. Herein, a novel supramolecular deep eutectic solvent (SUPRADES), comprising ethylene glycol and citric acid in 5:1 M ratio, and β-cyclodextrin (β-CD) in a concentration of 3.5% (w/w), was developed to be efficient for pretreating wheat straw. The delignification rate, cellulose enzymatic digestibility, and hemicellulose removal reached 90.45%, 97.36% and 87.24%, respectively, which may be attributed to the introduction of β-CD with superior ability of both adsorption and in-situ lignin protection to efficiently remove lignin with intact structure from cellulose surface. The mechanisms of high-efficiency lignin extraction/protection were systematically illustrated by adsorption kinetics. Moreover, Trichosporon cutaneum grown on the hemicellulose and cellulose fractions after pretreatment afforded 8.8 g total lipids from 100 g wheat straw. The green SUPARDES pretreatment strategy offers a new avenue for upgrading lignocellulose to biofuels.

A new look at the kinetics of oxygen delignification of softwood kraft pulp

Abstract Using a Berty-type CSTR reactor, Ji (2007. Kinetics and mechanism of oxygen delignification, Ph.D. thesis. The University of Maine) obtained oxygen delignification kinetics first order in lignin when neglecting the higher initial delignification phase. In the present study the same Berty/CSTR reactor with an improved temperature control was used to determine the oxygen delignification kinetics of Southern Pine kraft pulp, with the kinetics now corrected for lignin removed by oxygen-free alkaline leaching. This removes the initial high delignification rate peak so that the kinetics over the entire lignin range can be modelled as first order in “reactive” lignin, which is lignin corrected for a small amount of unreactive lignin. It suggests that softwood pulp oxygen delignification consists of two contributions; phenolic delignification and alkaline leaching. The initial alkaline leaching phase is mathematically described by semi-infinite alkaline diffusion of dissolved lignin trapped in the cell wall after pulp washing. For phenolic delignification, the reaction orders in alkali concentration and oxygen of the power law delignification equation are 0.3 and 0.44 respectively, while the activation energy is 63 kJ/mol. Taking into account the unreactive HexA, the small amount of unreactive lignin, and the lignin removed by alkaline leaching, the kappa number is well predicted by the new delignification kinetics.

On the modeling of continuous kraft pulp digesters: Inclusion of wood characteristics

In order to improve the pulp quality, it is essential to understand the influence of wood characteristics in the Kraft process, highlighting the methylglucuronic (MeGlcA) and hexenuronic (HexA) acids contents, and the syringyl/guaiacyl (S/G) ratio. Since their monitoring is still inefficient, it becomes difficult to use fully data-driven modeling approaches. Therefore, it is important to improve consolidated phenomenological models. In this work, an extended Purdue model was developed to simulate a continuous kraft pulp digester. Unlike most works, we considered the formation of HexA from MeGlcA and the dissolution of both compounds. We also considered the contribution of HexA to the kappa number, an important key performance indicator. As an innovation, we proposed the addition of the S/G ratio influence on the delignification rate of hardwoods by using experimental data taken from literature. The steady-state profiles and dynamic responses were similar to those found in the base work. The blow-line kappa number was 20% higher than that obtained disconsidering HexA. By performing a sensitivity analysis, the steady-state profile of kappa number proved to be very sensitive to variations in the S/G ratio. Thus, the results confirmed the importance of wood characteristics in the kraft pulping.

Influence of single gummy component removal/retention on the physicochemical properties of fibrilia fiber and the reaction behavior of the other components in the degumming process

Although many degumming methods for fibrilia fiber have been established, the reaction priority of the gums and the influence of single gummy component removal/retention on the fiber property and the reaction behavior of the other components remain unclear. This study analyzed the above issues by the observing the change of fiber in microbial-mechanical ‘enzyme peeling’ and gas phase ozone treatment. Results showed that pectin removal could increase the fiber density significantly (∼60.3%) but would not cause damage to the fiber tenacity. The 2.5–4.5% pectin in untreated fiber could strongly restrict the removal of lignin and hemicellulose. Lignin had less influence on fiber density than pectin. The detailed composition of hemicellulose had a significant effect on fiber tenacity: the retention of xylan and mannan caused damage and benefit, respectively, to fiber tenacity. After the removal of 90.0% pectin and 23.0% hemicellulose, a deep delignification rate (&gt;70.0%) could be obtained. The delignification rate of 70.0–80.0% was beneficial for the density decreasing and tenacity increasing of the fiber, while a delignification rate over 80.0% would cause the collapse of the cellulose structure and thus damage the fiber property.