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Lignin is the most abundant natural aromatic macromolecule in the nature, but its high value-added utilization has been seriously hindered by the highly random and branched structures and the high difficulty in separation and purification. A microwave-assisted ternary deep eutectic solvent (DES) composed by formic acid, lactic acid and choline chloride was developed for lignin pretreatment. The effects of three types of DES on main characteristics of lignin were investigated, and the corresponding dissolution mechanism was proposed. The results showed that, the microwave-assisted ternary DES pretreatment showed an obvious improvement on main characteristics of regenerated lignin, e.g., a higher purity, lower molecular weight with reduced dispersity, improved thermal stability, higher phenolic hydroxyl content, and increased antioxidative activity in comparison with control. It is expected that the lignin macromolecular can be facile regulated and upgraded by the proposed ternary DES., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Combining chemi-mechanical pulping with autohydrolysis pretreatment is an efficient and value-added utilization approach for lignocellulosic biomass in paper industry. To further promote the utilization of autohydrolyzed biomass in chemi-mechanical pulping, the color evolution of poplar wood chips in autohydrolysis pretreatment and its chromogenic mechanism were investigated by using CIELab color system, FT-IR, NMR and GPC. The results showed that the total color difference ΔE* increased obviously, which were remarkable as the combined hydrolysis factor (CHF) increased. The lignin content led to a more significant influence on the color of poplar wood chips than the extractives. The autohydrolysis pretreatment with a higher CHF accelerated the degradation and subsequent condensation of lignin, resulting in the formation of chromophoric groups, such as Hibbert ketone, quinones and quinone methides. It is of great significance for biomass refinery and paper industry to reveal the color evolution of poplar wood chips caused by autohydrolysis pretreatment from the point of view of chemical components' structure., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Research on biodegradable cellulose composite film with unique properties is of significance to alleviate current dependency on petroleum-based polymers, and to promote highly efficient utilization of lignocellulosic biomass. Lignin nanoparticles (LNPs) have been considered as a promising material for high value-added products. In this study, LNPs were prepared from corncob lignin via anti-solvent precipitation method, and then characterized by FTIR, TGA, AFM, and NMR. The CNF@CLNPs composite film was fabricated by blending CLNPs with CNF. The results showed that the CLNPs had an average diameter of about 118 nm, meanwhile the main structures and properties of corncob lignin were maintained. The CNF@CLNPs composite film exhibited a high ultraviolet resistance, and a good antibacterial activity against both Escherichia coli and Staphylococcus aureus. It is expected that the CNF@CLNPs composite film would have potential applications in outdoor materials and food packaging., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Lignocellulosic biomass is regarded as an ideal renewable resource for replacing traditional fossil fuels. Corncob residues (CRs) generated after hemicelluloses pre-extraction of corncobs were potential feedstocks to produce lignin-based products. Three lignin fractions, i.e., dioxane lignin (DL), milled-wood lignin (MWL), and enzymatic mild acidolysis lignin (EMAL), were isolated from CRs and characterized by HPLC, GPC, FT-IR, NMR, and TGA to reveal characteristics of CRs lignin to better understand its potential applications. The results showed that the yield of DL, MWL and EMAL were 12.8%, 14.7% and 15.6%, respectively. The molecular weight of DL, MWL and EMAL were 2001, 5391, and 2629 g/mol, respectively. The EMAL and MWL had similar structural features including guaiacyl and syringyl units, β-O-4' aryl ether, p-coumaric acids, ferulates, and phenylcoumarans, while the structure of DL was relatively simple. It is expected that this work will provide some useful information for the utilization of CRs in view of biorefinery., (Copyright © 2019. Published by Elsevier B.V.)

Chemi-mechanical pulping, a typical high-yield pulping method, combined with autohydrolysis pretreatment prior to pulping is an efficient and value-added utilization method for biomass in pulp and paper industry. This study investigated the surface lignin changes of poplar sapwood chips in autohydrolysis pretreatment and their effect on the subsequent alkali impregnation for chemi-mechanical pulping. The results showed that the surface lignin content went up with the increase of autohydrolysis intensity, and that the existence of the surface lignin had nearly no impact on the subsequent alkali impregnation in making chemi-mechanical pulps (CMPs) compared to the volume porosity, which was validated by using the stepwise regression analysis. It can be further concluded that autohydrolysis can facilitate the subsequent alkali impregnation of the autohydrolyzed sapwood chips in making CMP, which would be of significance for the combination of biomass refinery and pulp and paper industry., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The presence of dyes in wastewater effluents made from the textile industry is a major environmental problem due to their complex structure and poor biodegradability. In this study, a cationic lignin polymer was synthesized via the free radical polymerization of lignin with [2-(methacryloyloxy) ethyl] trimethyl ammonium chloride (METAC) and used to remove anionic azo-dyes (reactive black 5, RB5, and reactive orange 16, RO16) from simulated wastewater. The effects of pH, salt, and concentration of dyes, as well as the charge density and molecular weight of lignin-METAC polymer on dye removal were examined. Results demonstrated that lignin-METAC was an effective flocculant for the removal of dye via charge neutralization and bridging mechanisms. The dye removal efficiency of lignin-METAC polymer was independent of pH. The dosage of the lignin polymer required for reaching the maximum removal had a linear relationship with the dye concentration. The presence of inorganic salts including NaCl, NaNO₃, and Na₂SO₄ had a marginal effect on the dye removal. Under the optimized conditions, greater than 98% of RB5 and 94% of RO16 were removed at lignin-METAC concentrations of 120 mg/L and 105 mg/L in the dye solutions, respectively.

Dilute acid pre-extraction enhanced the mechanically refined poplar pulp substrates' enzymatic hydrolysis efficiency obviously. The results showed that the surface lignin distribution was changed significantly in residual wood chips and pulp substrates, and the surface lignin distribution showed important impact on the following enzymatic hydrolysis. Acid pre-extraction can lead to a redistribution of lignin in fiber cell walls, i.e., the lignin was degraded and migrated to fiber surface in the form of re-deposited lignin and pseudo-lignin. However, higher pre-extraction intensity was not desired due to the formation of redeposited lignin and pseudo-lignin. This study will help to reach a deeper understanding on the lignin distribution in the view of molecular and ultrastructure, and promote the development of a cost-efficient pretreatment strategy for biomass processing., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

As the rapid increasing demand for electrical energy in the world, the research on electrical energy storage becomes urgent and crucial, especially for these ones with the features of cost-effectiveness, high safety and outstanding performance. Aqueous zinc ion batteries (AZIBs) are regarded as environmentally friendly, safe, reliable, and promising devices for electrochemical energy storage systems. However, a variety of challenges such as zinc dendrite formation, corrosion and hydrogen evolution must be addressed for the practical, widespread application of AZIBs. Recently, there has been notable interest in utilizing renewable, biodegradable, and cost-effective lignocellulosic materials to address these challenges, as they have the potential to significantly improve the electrochemical performance of AZIBs. However, there is a lack of comprehensive and systematic summary, as well as a gap in theoretical analysis, on the role of lignocellulosic materials in improving AZIBs performance. The present review covers the development, concept, advantages, and challenges of AZIBs. The most recent advancements and progress on the lignocellulosic materials (including cellulose, lignin, and hemicelluloses) as electrodes, electrolytes and separators for AZIBs applications are summarized. A perspective on existing challenges, potential solutions, and promising prospects of lignocellulosic materials is outlined, aiming to provide the research community with essential technical insights that could drive the commercialization of green and sustainable lignocellulosic materials in high-performance AZIBs. [Display omitted] • The advantages and current challenges of AZIBs have been systematically discussed. • The recent progress of developing lignocellulosic materials for AZIBs has been reviewed. • The strategies for improving the performance of AZIBs via incorporating lignocellulosic materials have been summarized. • The challenges and perspectives in developing lignocellulosic materials for advanced AZIBs have been addressed. [ABSTRACT FROM AUTHOR]

An efficient separation technology for hydrolysates towards a full valorization of bamboo is still a tough challenge, especially regarding the lignin and lignin-carbohydrate complexes (LCCs). The present study aimed to develop a facile approach using organic solvent extraction for efficiently fractionating the main components of bamboo hydrolysates. The high-purity lignin with only a trace of carbohydrates was first obtained by precipitation of the bamboo hydrolysate. The water-soluble lignin (WSL) fraction was extracted in organic solvent through a three-stage organic solvent extraction process, and the hemicellulosic sugars with increased purity were also collected. Furthermore, a thorough characterization including various NMR techniques (31P, 13C, and 2D-HSQC), GPC, and GC-MS was conducted to the obtained lignin-rich-fractions. It was found that the WSL fraction contained abundant functional groups and tremendous amount of LCC structures. As compared to native LCC of bamboo, the WSL fraction exhibited more typical LCC linkages, i.e. phenyl glycoside linkage, which is the main type of chemical linkage between lignin and carbohydrate in both LCC samples. The results demonstrate that organic phase extraction is a highly efficient protocol for the fractionation of hydrolysate and the isolation of LCC-rich streams possessing great potential applications. [ABSTRACT FROM AUTHOR]

Bamboo chips were efficiently fractionated using an integrated process of autohydrolysis and formic acid to induce rapid delignification. Autohydrolysis pretreatment facilitated oligosaccharide production, while the subsequent rapid-delignification using formic acid at a low liquid/solid ratio with a relatively short reaction time allowed obtaining cellulose fibers and lignin. The major inter-unit linkages of side-chain in lignin were cleaved during the combined fractionation process. The lignin fraction exhibited higher purity, more phenolic OH groups, less condensed phenolic OH groups, and higher syringyl/guaiacyl ratio (S/G) as compared to MWL and formic acid lignin from the direct formic acid delignification. These results indicate that the combined fractionation process presents a promising approach to the commercial utilization in the biorefinery industry. [ABSTRACT FROM AUTHOR]

To promote the efficient utilization of lignocellulosic materials, one-step fractionation by formic acid-based organosolv process under pressure has been studied for converting lignocellulose in its main components. Lignin and hemicelluloses were selectively dissolved, while cellulose was not obviously degraded. Under optimized conditions (85% formic acid, a liquor-to-solid ratio of 7:1, and a temperature of 145°C for 45 min), this process provided a high efficient way to separate the main components of bamboo, obtaining 42.2% cellulose pulp, 31.5% lignin, 8.5% hemicellulose-rich fraction, 3.56% furfural and 3.80% acetic acid. Cellulose pulp with satisfying viscosity could easily be bleached to a high brightness of over 87% ISO with a short bleaching sequence, and had an acceptable paper strength properties. The recovered lignin fraction contained a small amount of carbohydrates and a considerable part of proteins and p-hydroxycinnamates. Additionally, the organic substances in hemicellulose-rich fraction obtained was composed of 95% carbohydrates, most of which was monosaccharides, as well as 5% lignin. [ABSTRACT FROM AUTHOR]

Bamboo was fractionated using formic acid based on a one-step organosolv process under high pressure (at 145 °C for 45 min, 0.3 MPa) and at atmospheric pressure (at 101 °C for 120 min), respectively. High-pressure formic acid lignin, atmospheric formic acid lignin and milled wood lignin of bamboo were subjected to comprehensive structural characterization using gel permeation chromatography (GPC), Fourier transform infrared (FTIR) and solution-state NMR techniques ( 1 H, 13 C, 2D-HSQC, and 31 P-NMR spectroscopies). The results indicated that the formic acid fractionation under high pressure presents a quick and efficient delignification method by enhancing the cleavage of interunitary bonds in lignin (β-O-4′, β-β and β-5′), and dissolved lignin also occurred condensation reaction. As compared to atmospheric formic acid lignin, high-pressure formic acid lignin obtained showed higher purity and yield, and had relatively higher contents of phenolic and carboxylic groups. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass exhibits a promising potential for production of carbon materials. Nitrogen and phosphorus co-doped carbon quantum dots (N,P-CQDs) were fabricated via (NH 4) 2 HPO 4 assisted hydrothermal treatment of cellulose pulp fibers. The as-prepared N,P-CQDs were characterized by HRTEM, FTIR, fluorescence and UV–vis, and then incorporated into g-C 3 N 4 (CN) through sonication and liquid deposition, forming N,P-CQDs/sonication treated g-C 3 N 4 (C-SCN) composites, which were then explored as photocatalysts. The photocatalytic ability of C-SCN towards model lignin was further analyzed. The results showed that, the fluorescence intensity and photoluminescence performance of N,P-CQDs were much higher than that of CQDs; the heterojunction was successfully constructed between the composites of N,P-CQDs and SCN; the incorporation of N,P-CQDs enhanced the visible light absorption, but reduced the band gap of the composite heterojunction; the resultant photocatalysts exhibited a good photocatalytic ability of model lignin via catalyze the fracture of β –O–4′ ether bond and C C bond, i.e., the photocatalytic degradation ratio reached up to 95.5 %; and the photocatalytic reaction generated some valuable organics such as phenyl formate, benzaldehyde, and benzoic acid. This study would promote the high value-added utilization of lignocellulosic resources especially in the transformation of lignin, conforming the concept of sustainable development. • Nitrogen and phosphorus co-doped CQDs was prepared from cellulose pulp. • N,P-CQDs exhibited a much better optical properties than CQDs. • N,P-CQDs/g-C 3 N 4 composites were fabricated and explored as photocatalysts. • N,P-CQDs enhanced photocatalytic capacity of CQDs/g-C 3 N 4 towards lignin model. • Some valuable chemicals were generated during the photocatalytic reaction. [ABSTRACT FROM AUTHOR]

Lignin is the main factor inhibiting enzymatic hydrolysis of lignocellulosic biomass. Different pretreatments can alter chemical and structural characteristics of lignin, thus affecting its adsorption capacity of enzymes. Herein, enzymatic mild acid lignin (EMAL) was separated from poplar branch wood chips as substrates resulted from different combined pretreatments, and then characterized and adsorbed by enzymes, so as to study the effects of different pretreatments on enzyme adsorption capacity. The results showed that the phenolic hydroxyl content and C C bond number of lignin increased after hydrothermal pretreatment, which increased the unproductive adsorption of mixed enzymes through hydrophobic interaction and hydrogen bonds. Chemical pretreatment after hydrothermal pretreatment can further reduce the unproductive adsorption of lignin on mixed enzymes, improving the enzymatic hydrolysis of substrates. This study would help to unmask the adsorption of mixed enzymes on lignin resulted from combined pretreatments, and facilitate the rapid development of efficient pretreatment for lignocellulosic biomass. [Display omitted] • Effects of hydrothermal & chemi-mechanical pretreatment on lignin was studied. • Adsorption capacity and mechanism of mixed enzymes onto lignin were investigated. • Relationship between lignin characteristics and enzyme adsorption was studied. • Isothermal adsorption and adsorption kinetics of enzymes on lignin were analyzed. • Adsorption mechanism of enzymes on different lignin was revealed. [ABSTRACT FROM AUTHOR]

Lignin is the most abundant aromatic source in nature, whose efficient utilization has been recognized as a key challenge in biorefinery. Deep eutectic solvents (DES) exhibit excellent solubility for lignin, and are promising solvent for facilitating the lignin-first biorefinery and valorization of lignin. Herein, microwave-assisted carboxylic acid-based DES pretreatment was applied on corncob; the effects of the pretreatment on physical and chemical structures of lignin was investigated. The results showed that microwave-assisted DES pretreatment enhanced the deconstruction efficiency of corncob in terms of the high removal ratio and recovery yield of DES-lignin; Moreover, the resultant DES-lignin exhibited lower molecular weights and particle size than that from conventional DES pretreatment, and presented abundant phenolic OH groups. This study provide a highly efficient pretreatment approach for the agricultural residues and the sufficient understanding on structural and chemical characteristics of resultant DES-lignin will promote its subsequent conversion and application. [Display omitted] • Microwave-assisted carboxylic acid-based DES pretreatment was applied on corncob. • Microwave-assisted DES pretreatment enhanced deconstruction efficiency. • The pretreatment exhibited a high removal ratio of lignin and hemicelluloses. • The lignin had a good recovery yield, high purity, and good thermal stability. • The lignin had lower particle size & narrow distribution, and high reactivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lignin-derived GQDs were prepared via phosphous acid-assisted hydrothermal process. • P-LGQDs have excellent electronic, optical properties, and pH-responsiveness. • P-LGQDs/g-C 3 N 4 shows good photocatalytic degradation ability for MB & model lignin. • Degradation products such as phenyl formate can be generated from model lignin. Value- added utilization of carbon-rich lignin has become an urgent and attractive research topic due to its abundance, low cost, and sustainability. How to convert lignin in an efficient and green strategy is the bottleneck limiting its valorization. Herein, a phosphorous acid (P) assisted hydrothermal process to produce lignin-derived graphene quantum dots (P-LGQDs) was developed. The as-prepared P-LGQDs was comprehensively characterized, and explored in photocatalysis. The P-LGQDs have a narrow particle size distribution, excellent electronic and optical properties, and a good pH-responsiveness. The P-LGQDs was further used to construct P-LGQDs/g-C 3 N 4 heterojunction, showing excellent photocatalytic degradation ability towards methylene blue and model lignin (94.6 % and 93.1 %, respectively). This present study offers a universal strategy for the value-added utilization and valorization of lignin. [ABSTRACT FROM AUTHOR]

The utilization of agricultural residues to produce bio‐based fuels, chemicals, and new materials is essential for the sustainable development of human society. Corncob residues are potential feedstocks to produce fermentable sugars because of their high cellulose content. The enzymatically hydrolyzed corncob residues containing a large amount of lignin are first explored as raw material to prepare activated carbon by chemical activation. In this study, the conditions for preparing activated carbon with CaCl2 are optimized and compared with other activators; the activated carbon are characterized by FTIR, Brunauer–Emmett–Teller (BET), and SEM, as well as adsorption of Cu(II). The optimized conditions of preparing activated carbon from lignin‐rich enzymatically hydrolyzed corncob residues with CaCl2 are obtained. The as‐prepared activated carbon exhibit good adsorption capacity of Cu(II), that is, the adsorption capacity is up to 49.21 mg g−1 under the optimized conditions. [ABSTRACT FROM AUTHOR]