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The efficient removal of lignin is crucial for process optimization, as it enhances the exposure of polar groups in wood and provides interfacial binding sites for subsequent material modifications. In this study, an environmentally friendly peracetic acid/ hydrogen peroxide system was employed to delignify fast-growing wood. The results indicated mass loss rates of 30.7% for poplar and 31.3% for Chinese fir, with corresponding decreases in relative lignin content by 95.3% and 87.2%, respectively. Additionally, the specific surface area increased by 6.4% in poplar and 30.9% in Chinese fir. The relative crystallinity was enhanced by 31.2% in poplar and 15.7% in Chinese fir, and the O/C ratio increased by 29.6% and 19.7%, respectively. Microsocopic morphological analysis revealed noticeably thinner and slightly collapsed cell walls in the treated samples. The disappearance of lignin-specific peaks at 1507 cm −1 , 1460 cm −1 , and 1264 cm −1 confirmed the effective removal of lignin. Additionally, delignification resulted in a lower pyrolysis temperature, increased surface brightness, and reduced color variation. Due to the differences in internal structures and chemical compositions between poplar and Chinese fir, the effects of lignin removal varied, leading to significant changes in their physicochemical properties. These findings provide a theoretical foundational for lignin removal from wood and support future efforts in wood functionalization.

This work reports the isolation of cellulose from giant reed through an ecofriendly multistep procedure including alkali treatment and totally chlorine free delignification, followed by acid hydrolysis to prepare microcrystalline cellulose using different acidic solutions (HCl, HNO 3 , H 2 SO 4 , HCl/HNO 3 (2:1, v/v), and HCl/H 2 SO 4 (2:1, v/v)). Several characterizations were performed in order to investigate the properties of each sample. FTIR results affirmed that the successive alkali treatment, totally chlorine free bleaching, and acid hydrolysis remove efficiently hemicellulose, lignin, and amorphous regions from the giant reed, and showed that the characteristic peaks of the prepared giant reed microcrystalline celluloses (GRMCC-HCl, GRMCC-HNO 3 , GRMCC-H 2 SO 4 , GRMCC-HCl/HNO 3 , and GRMCC-HCl/H 2 SO 4 ) were similar to those of the commercial one. XRD measurements exhibited that microcrystalline cellulose produced from giant reed belong to cellulose I allomorph, with crystallinity index ranging from 73 to 80%. SEM micrographs revealed non-uniform micro sized rod-like shape morphology of GRMCC samples. The thermal analysis results displayed that the thermal decomposition of the obtained GRMCCs shifted to higher temperatures compared to the respective giant reed cellulose. This work opened a new pathway to prepare cellulose and microcrystalline cellulose from an abundant natural source using an ecofriendly process, and it could be expected to have applications in several areas. Graphic abstract

Lignocellulosic materials are mainly consisted of lignin, cellulose, and hemicellulose. Lignin is recognized as the main obstacle for the enzymatic saccharification of cellulose towards the fermentable sugars’ production. Hence, the removal of lignin from the lignocellulosic feedstock is beneficial for reducing the recalcitrance of lignocellulose for enzymatic attack. For this purpose, various different alkaline pretreatments were examined in order to study their effect on the enzymatic saccharification of wheat straw, as a typical lignocellulosic material. Results revealed that the alkaline pretreatments promoted delignification reactions. Regarding the removal of lignin, the most efficient pretreatments were alkaline treatment with hydrogen peroxide 10% and NaOH 2% autoclave with delignification efficiencies of 89.60% and 84.86% respectively. X-ray diffraction analysis was performed to enlighten the structural changes of raw and pretreated materials. The higher the delignification of the raw material, the higher the conversion of cellulose during enzymatic saccharification. In all cases after enzymatic saccharification, the cellulosic conversion was much higher (32–77%) than the untreated wheat straw (8.6%). After undergoing alkaline peroxide 10% pretreatment and cellulase treatment, 99% of the initial raw straw was eventually solubilized. Thus, wheat straw could be considered as an ideal material for the production of glucose with proper pretreatments and effective enzymatic hydrolysis.

In this study, sugarcane bagasse (SB) was strategically subjected to a delignification process followed by the in situ growth of multi-layered molybdenum disulfide (MoS 2 ) nanosheets with hexagonal phase (2H-phase) crystal structure via hydrothermal treatment. The MoS 2 nanosheets underwent self-assembly to form nanoflower-like structures in the aligned cellulose inter-channels of delignified sugarcane bagasse (DSB), the mechanism of which was understood through FTIR and XPS spectroscopic studies. DSB, due to its porous morphology and abundant hydroxyl groups, shows remediation capabilities of methylene blue (MB) dye through physio-sorption but shows a low adsorption capacity of 80.21 mg/g. To improve the removal capacity, DSB after in situ growth of MoS 2 (DSB-MoS 2 ) shows enhanced dye degradation to 114.3 mg/g (in the dark) which further improved to 158.74 mg/g during photodegradation, due to catalytically active MoS 2 . Interestingly, DSB-MoS 2 was capable of continuous dye degradation with recyclability for three cycles, reaching an efficiency of > 83%, along with a strong antibacterial response against Gram-positive Staphylococcus aureus ( S.aureus ) and Gram-negative Escherichia coli ( E. coli ). The present study introduces a unique strategy for the up-conversion of agricultural biomass into value-added bio-adsorbents, which can effectively and economically address the remediation of dyes with simultaneous microbial decontamination from polluted wastewater streams.

The synergistic effect of ultrasonication with deep eutectic solvent (DES) on pretreatment of oil palm empty fruit bunch (OPEFB) was investigated. Three different types of DESs, namely choline chloride:lactic acid (ChCl:LA), choline chloride:urea (ChCl:U) and choline chloride:glycerol (ChCl:G) were applied. The performance of the pretreatment was evaluated based on yield of reducing sugars, lignin content, crystallinity index, structural and morphology changes. ChCl:LA pretreated OPEFB attained the highest yield of reducing sugars (36.7%) under the action of ultrasonication for 15 min at sonication power 60% (210 W) and temperature 50 °C, followed by ChCl:U (35.8%) and ChCl:G (35.3%). Under these conditions, ChCl:LA pretreated OPEFB showed significant change in structural and morphology, associated with the lowest crystallinity and lignin content. ChCl:LA promoted the pretreatment process in view of its intrinsic properties of low viscosity and low surface tension. The incorporation of ultrasonication in DES pretreatment significantly increased the reducing sugars yield suggested the synergistic effect of ultrasonication with DES pretreatment. These signifies that ultrasound-assisted DES pretreatment could be a promising alternative pretreatment technique for lignocellulosic biomass.Graphic abstract

Wood is an attractive and inherently sustainable alternative to many conventional materials. Recent research on improving wood mechanical strength emphasizes wood densification through the partial removal of lignin and hemicelluloses, therefore the chemical and physical properties of delignified and densified wood require further investigation. In this study, poplar wood samples were subjected to alkali and maleic acid hydrotropic delignification with varying degrees of lignin and hemicellulose removal followed by hot pressing, and the microstructure, chemical properties, and dimensional stability of densified wood through delignification were evaluated. The results showed that the complete wood cell collapse was observed near the surface of all the delignified wood blocks, as well as some micro-cracks in the cell walls. The chemical analysis indicated that delignification occurred mainly near the surface of the wood blocks and enhanced hydrogen bonding among the aligned cellulose fibers. For dimensional stability, the set recovery decreased with the increase in alkali dosage, and the considerable fixation of compressive deformation was obtained by a post-densification hydrothermal treatment at 180 °C. These results have demonstrated that the densified wood with delignification can be easily fabricated using the proposed method, and the densified wood exhibited great potential to be used as a sustainable material.

Lignin, the most abundant aromatic polymer in nature, plays a critical role in lignocellulosic biomasses by providing structural support. However, its presence complicates the industrial exploitation of these materials for biofuels, paper production and other high-value compounds. Annually, the industrial extraction of lignin reaches an estimated 225 million tons, yet only a fraction is recovered for reuse, with most incinerated as low-value fuel. The growing interest in lignin potential has sparked research into sustainable recovery methods from lignocellulosic agro-industrial wastes. This review examines the chemical, physical and physicochemical processes for isolating lignin, focusing on innovative, sustainable technologies that align with the principles of a circular economy. Key challenges include lignin structural complexity and heterogeneity, which hinder its efficient extraction and application. Nonetheless, its properties such as high thermal stability, biodegradability and abundant carbon content place lignin as a promising material for diverse industrial applications, including chemical synthesis and energy generation. A structured analysis of advancements in lignin extraction, characterization and valorization offers insights into transforming this undervalued by-product into a vital resource, reducing reliance on non-renewable materials while addressing environmental sustainability.

Background The efficient utilization of lignocellulosic biomass for biofuel production has received increasing attention. Previous studies have investigated the pretreatment process of biomass, but the detailed enzymatic hydrolysis process of pretreated biomass remains largely unclear. Thus, this study investigated the pretreatment efficiency of dilute alkali, acid, hydrogen peroxide and its ultimate effects on enzymatic hydrolysis. Furthermore, to better understand the enzymatic digestion process of alkali-pretreated sweet sorghum straw (SSS), multimodal microscopy techniques were used to visualize the enzymatic hydrolysis process. Result After pretreatment with alkali, an enzymatic hydrolysis efficiency of 86.44% was obtained, which increased by 99.54% compared to the untreated straw (43.23%). The FTIR, XRD and SEM characterization revealed a sequence of microstructural changes occurring in plant cell walls after pretreatment, including the destruction of lignin–polysaccharide interactions, the increase of porosity and crystallinity, and reduction of recalcitrance. During the course of hydrolysis, the cellulase dissolved the cell walls in the same manner and the digestion firstly occurred from the middle of cell walls and then toward the cell wall corners. The CLSM coupled with fluorescent labeling demonstrated that the sclerenchyma cells and vascular bundles in natural SSS were highly lignified, which caused the nonproductive bindings of cellulase on lignin. However, the efficient delignification significantly increased the accessibility and digestibility of cellulase to biomass, thereby improving the saccharification efficiency. Conclusion This work will be helpful in investigating the biomass pretreatment and its structural characterization. In addition, the visualization results of the enzymatic hydrolysis process of pretreated lignocellulose could be used for guidance to explore the lignocellulosic biomass processing and large-scale biofuel production.

The thermal degradation reactivities of cellulose and hemicellulose are substantially different in Japanese cedar ( Cryptomeria japonica , a softwood) and Japanese beech ( Fagus crenata , a hardwood). Uronic acid and its salts act as acid and base catalysts, respectively, and their specific placement in the cell walls has been considered a factor that influences degradation reactivity. In this study, the role of lignin in degradation reactivity was investigated using holocellulose prepared from cedar and beech woods. The thermal degradation reactivities of cellulose and hemicellulose in holocellulose were evaluated according to the recovery of hydrolyzable sugars from heat-treated samples and compared with those of wood samples. Results show that the reactivities of xylan and glucomannan in both woods became similar to those of the corresponding isolated samples when lignin was removed. By contrast, the cellulose in both woods became more reactive when lignin was removed, and the degradation could be separated into two modes depending on the reactivity. These results were analyzed in terms of the effect of lignin on the matrix of cell walls and the interaction between the matrix and surface molecules of cellulose microfibrils. Differential thermogravimetric curves of the holocellulose samples were obtained and explained in terms of the degradation of hemicellulose and cellulose. The reported findings will provide insights into the research fields of wood pyrolysis and cell wall ultrastructures.

Extracellular enzymes produced from Streptomyces have the potential to replace toxic chemicals that are being used in various industries. The endorsement of this replacement has not received a better platform in developing countries. In this review, we have discussed the impact of chemicals and conventional practices on environmental health, and the role of extracellular enzymes to replace these practices. Burning of fossil fuels and agriculture residue is a global issue, but the production of biofuel using extracellular enzymes may be the single key to solve all these issues. We have discussed the replacement of hazardous chemicals with the use of xylanase, cellulase, and pectinase in food industries. In paper industries, delignification was done by the chemical treatment, but xylanase and laccase have the efficient potential to remove the lignin from pulp. In textile industries, the conventional method includes the chemicals which affect the nervous system and other organs. The use of xylanase, cellulase, and pectinase in different processes can give a safe and environment-friendly option to textile industries. Hazardous chemical pesticides can be replaced by the use of chitinase as an insecticide and fungicide in agricultural practices.