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Lignin can affect the enzymatic hydrolysis efficiency of lignocellulose. In this study, the lignin isolated from sugarcane bagasse (SCB) pretreated with p-toluenesulfonic acid (PL) was firstly aminated, and then the effects of PL and aminated PL (APL) on the bagasse enzymatic hydrolysis efficiency (EHE) were investigated. The results showed that the addition of PL and APL promoted the EHE, and EHE with APL (73.82 %) was higher than PL (51.39 %). To explore the reason, the data were further analyzed including cellulase adsorption capacity, enzyme activity, cellulase-lignin interaction, and molecular docking. It was found that APL adsorbed more cellulase (27.83 mg protein/g lignin) than PL (4.96 mg protein/g lignin), resulting from the greater interaction force and lower binding free energy between APL and cellulase. The addition of APL more remarkably enhanced the cellobiohydrolase and endoglucanase activities than PL due to more effectively inducing cellulase conformation optimization. [Display omitted] • Enzymatic hydrolysis of cellulosic substrate was enhanced from 45.83 % to 73.82 % by aminated lignin. • Aminated lignin adsorbed more cellulase molecules. • Activities of cellobiohydrolase (CBH) and endoglucosidase (EG) were promoted by aminated lignin. • Aminated lignin owned lower binding energy with cellulase. [ABSTRACT FROM AUTHOR]

Delignification of lignocellulose using basic ionic liquids (BILs) such as choline lysinate ([Ch][Lys]) is a promising method due to its high efficiency, mild conditions, and low toxicity. Typically, the following precipitation of lignin by adding acid media makes it challenging to recycle BILs. Herein, we explored a series of low-cost and recyclable alcohols as anti-solvents, including methanol (MeOH), ethanol (EtOH), iso-propanol (i-PrOH), and tert-butanol (t-BuOH), for recovering [Ch][Lys] and precipitating lignin without adding an acid from water-free [Ch][Lys] (case 1) and aqueous [Ch][Lys] (case 2). For case 1, lignin recovery followed the order of EtOH > i-PrOH > t-BuOH (MeOH was not able to recover lignin and [Ch][Lys]), which was negatively correlated with their pKa values, indicating the effect of the inhibited generation of a basic anion (e.g. EtO− from EtOH) from –NH2 in [Ch][Lys] on lignin precipitation. t-BuOH showed the highest lignin recovery of 99.7%, ensuring the high purity of the recovered [Ch][Lys] (recovery of 94.7%). Lignin deprotonation and depolymerization were detected. For case 2, t-BuOH also facilitated the recovery of lignin from an aqueous lignin–[Ch][Lys] system with a nearly quantitative lignin recovery, yet with lower [Ch][Lys] recovery of 81.7% and 64.0% at the [Ch][Lys] : water ratios (w/w) of 7 : 3 and 1 : 9, respectively. The lower recovery of [Ch][Lys] might be due to the poor dispersity of lignin solid in t-BuOH, and water also enhanced the deprotonation of lignin, thus making lignin precipitation more difficult. Based on the results, a deprotonation-based lignin dissolution mechanism has been proposed, which also helps to understand lignin dissolution and precipitation in a [Ch][Lys]-based system. [ABSTRACT FROM AUTHOR]

The utilization of biomass as a carbon source for the synthesis of renewable solid acid catalysts (SA) has emerged as a prominent research direction in the field of heterogeneous catalysis. Based on the challenges associated with reusing residues from lignocellulosic biorefining, the biomass‐based SA (BCSA) were prepared using poplar sawdust (PS), hydrothermally pretreated PS (PPS), and the residue of PPS's enzymatic hydrolysis (ER). The characterization revealed that all three types of BCSA were loaded with catalytic groups, and the BCSA synthesized using ER rich in lignin components exhibited a highly efficient catalytic structure. Furthermore, the catalysis of a 20 g/L xylose solution with BCSA‐ER as SA also achieved the highest furfural yield (89.3%) and furfural selectivity (90.3%). The findings of this study suggested that lignin holds significant potential as a carbon carrier for SA, thereby offering a viable solution for utilizing by‐products from lignocellulosic biorefining. [ABSTRACT FROM AUTHOR]

Alkaline-catalyzed organosolv pretreatment of lignocellulosic biomass affords excellent delignification, yielding a holocellulose-rich substrate for fermentable sugar production. However, complete lignin removal is impractical, and residual lignin also exacerbates negative effects on subsequent enzymatic hydrolysis. Herein, a novel strategy of developing surfactant-assisted organosolv pretreatment (Triton-X 100, AEO 9 and Tween 80) for in situ lignin modification was proposed to overcome this issue. The results indicated that the pretreated substrates showed considerable enzymatic hydrolyzability with a 15.7%–38.3% higher sugar yield compared to the control group without surfactants. Surfactants could graft on both residual and dissolved lignin through etherification, forming α-etherified lignin, though without significantly changing the component distribution and substrate-related properties. Quantum chemical calculations provided theoretical evidence of strong H-bonding and pronounced interaction energy between lignin and surfactants (maximally at −48.4 kcal mol−1). In particular, this surfactant modification decreased the aliphatic –OH and phenolic –OH contents of residual lignin by 16.0%–22.4% and 13.8%–28.8%, respectively. The reduction of –OH groups mitigated non-productive adsorption between lignin and cellulases via H-bonding interaction, which exhibited a significant correlation with the increased enzymatic hydrolyzability (>−0.9). Overall, this study offers valuable insight into the fundamental understanding of the mechanism involved in lignin modification during surfactant-assisted pretreatment and lignin–enzyme interaction during enzymatic hydrolysis. The new findings underscore the potential application of surfactants in organosolv pretreatment to achieve a feasible approach for developing an efficient enzyme-mediated lignocellulosic sugar platform. [ABSTRACT FROM AUTHOR]

Enzymatic hydrolysis contributes to obtaining fermentable sugars using pretreated lignocellulose materials for bioethanol generation. Unfortunately, the pretreatment of lignocellulose causes low substrate enzymatic hydrolysis, which is due to the structure changes of lignin to produce main phenolic by-products and non-productive cellulase adsorption. It is reported that modified lignin enhances the speed of enzymatic hydrolysis through single means to decrease the negative effects of fermentation inhibitors or non-productive cellulase adsorption. However, a suitable modified lignin should be selected to simultaneously reduce the fermentation inhibitors concentration and non-productive cellulase adsorption for saving resources and maximizing the enzymatic hydrolysis productivity. Meanwhile, the adsorption micro-mechanisms of modified lignin with fermentation inhibitors and cellulase remain elusive. In this review, different pretreatment effects toward lignin structure, and their impacts on subsequent enzymatic hydrolysis are analyzed. The main modification methods for lignin are presented. Density functional theory is used to screen suitable modification methods for the simultaneous reduction of fermentation inhibitors and non-productive cellulase adsorption. Lignin-fermentation inhibitors and lignin-cellulase interaction mechanisms are discussed using different advanced analysis techniques. This article addresses the gap in previous reviews concerning the application of modified lignin in the enhancement of bioethanol production. For the first time, based on existing studies, this work posits the hypothesis of applying theoretical simulations to screen efficient modified lignin-based adsorbents, in order to achieve a dual optimization of the detoxification and saccharification processes. We aim to improve the integrated lignocellulose transformation procedure for the effective generation of cleaner bioethanol. [Display omitted] • Effects of pretreatment in lignin structure and enzymatic hydrolysis are analyzed. • Lignin modification is the promising enhancement process to bioethanol production. • DFT calculation contributes to screening the suitable lignin modification methods. • Advanced methods to study inhibitors-lignin-cellulase interactions are reviewed. [ABSTRACT FROM AUTHOR]

Converting lignin into aromatic chemicals is a promising strategy for the high‐value utilization of lignocellulosic feedstock. However, the inherent heterogeneity of lignin poses a significant obstacle to achieving efficient conversion and optimal product yields within bio‐refinery systems. Herein, we employed a one‐step fractionation method to enhance lignin homogeneity and utilized the THF/DMSO‐EtONa (tetrahydrofuran/dimethyl sulfoxide‐sodium ethoxide) system to depolymerize the fractionated lignin. Three protic and three aprotic solvents were used for fractionation. The impact of the solvent properties on the structure and the depolymerization efficiency of the fractionated lignin was investigated. Methanol‐fractionated lignin generated the benzoic acid compounds with a yield of 30 wt%, 50 % higher than that of the unfractionated lignin. The polarities (δP), hydrogen bonding abilities (δH), and viscosities (η) of selected protic solvents showed strong linear correlation with molecular weight (Mw), polymer dispersity index (PDI), and syringyl/guaiacyl ratio (S/G ratio) of the fractionated lignin, as well as the total yield of benzoic acid compounds derived from the β‐O‐4 bond cleavage. This study elucidates the relationship between solvent properties and lignin structure and proposes a promising approach for refining lignin to enhance utilization efficiency, thereby presenting a potential strategy for value‐added application of complex lignin polymers. [ABSTRACT FROM AUTHOR]

Plant-based waste biomass with lignocellulose as an important component is produced in large quantities worldwide every year. The components of lignocellulose that typically exhibit high utilization value include cellulose and hemicellulose, as well as pentoses and hexoses derived from their hydrolysis. As a pretreatment for the hydrolysis process, delignification is a pivotal step to enhance cellulose/hemicellulose accessibility and achieve high yields of fermentable sugars. Additionally, deep eutectic solvents (DESs) are the most widely used solvents for delignification during biomass fractionation due to their clean and environmentally friendly attributes. DESs dissolve lignin by inducing a large amount of β-O-4 bond cleavage and partial carbon–carbon bond cleavage, retaining cellulose in the solid residue, while most of the hemicellulose is hydrolyzed in DES pretreatment. This article provides a comprehensive review of the influence of DESs in the lignocellulose separation process. Key factors such as lignin removal rate, sugar conversion rate, and product chemical structure are critically reviewed to assess the feasibility of employing DESs for lignocellulose separation. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonation carbon (HTCC) is emerging as a promising material for the adsorption and photodegradation of environmental contaminants. However, the chemical and structural properties of HTCC derived from different lignocellulose biomass have obvious impacts on adsorption and photodegradation. This work employed three different lignocellulose components, including cellulose, hemicellulose, and lignin to synthesize HTCC within a hydrothermal temperature range of 210~290 °C. In comparison to HTCC derived from cellulose and hemicellulose, HTCC derived from lignin (HTCC-L) demonstrated the optimal synergistic adsorption and photodegradation ability for TC degradation, achieving a 63.5% removal efficiency within 120 min. Characterization highlighted the crucial involvement of oxygenated functional groups, especially carboxyl groups, presented on the surface of HTCC-L in TC adsorption. Moreover, the photodegradation of HTCC-L was found to follow a non-radical mechanism, characterized by the charge transformation occurring between the excited unpaired electrons of HTCC-L and TC adsorbed on its surface. This work clarified the differences in HTCC derived from different lignocellulose components on the adsorption and photodegradation of organic pollutants, and provided a novel perspective on the application of HTCC in water treatment. [ABSTRACT FROM AUTHOR]

This study introduces an alternative approach towards lignocellulosic biomass fractionation. For this purpose, reactive eutectic media (REM) based on ammonium formate and different organic acids are investigated, possible products are identified, and the REM are employed for lignin extraction and terminal isolation of cellulose pulp from beech wood. The method promises a considerable process intensification by simultaneous separation of high purity cellulose pulp, lignin isolation as a cationically modified species, and production of value‐added chemicals from reaction products of the REM. This study puts a further focus on the generated cellulose pulp and investigates it with respect to surface charge and fiber length. [ABSTRACT FROM AUTHOR]

Pretreatment facilitates cost-effective operations on lignocellulosic biomass ranging from densification to deconstruction and bioproduct development. However, determining molecular-level mechanisms behind pretreatment and their effects has remained elusive. Here, we combine computational simulation and experiment to investigate the effects on wheat straw agricultural residue densification of an emerging pretreatment solvent, namely, a deep eutectic solvent (DES) consisting of choline chloride (ChCl) and oxalic acid (OA). Ab initio molecular dynamics indicates that dissociation of lignin from cellulose in lignin–carbohydrate complexes, which does not occur to a significant extent in aqueous solution, is favorable in the DES and occurs via cleavage of the guaiacyl : xylose ether bond linkage by OA. The ensuing hemicellulose removal exposes lignin to the DES which, molecular dynamics simulation indicates, leads to lignin expansion. The resulting changes in wheat straw fiber structure, lignin distribution, and functional group modifications upon DES treatment by scanning electron and fluorescence microscopy along with Fourier-transform infrared spectroscopy. The molecular expansion of lignin enhances inter-particle binding in wheat straw, leading to denser structures under pelletization. The resulting high mechanical stability and combustion properties make the wheat straw a suitable precursor of high-quality densified solids (e.g., solid biofuel). Overall, we shed light on the molecular-level mechanisms involved in DES pretreatment for biomass densification, demonstrated here in the development of a solid biofuel. The approach here illuminates the rational design from first chemical principles of methods to convert lignocellulosic resources into advanced materials. [ABSTRACT FROM AUTHOR]

Lignin is part of the lignocellulosic biomass found in hardwoods, softwoods, and herbaceous plants. It is isolated by fractionation and pulping processes, where it is considered a waste product and is mainly burned to generate electricity and heat. However, lignin is a biopolymer that can be a source of many chemicals of significant value after treatments of functionalisation or depolymerisation. The main processes for its valorisation require solubilisation in organic solvents, which may affect the process's mass balance and the biopolymer's chemical structure, as lignins are rarely completely soluble in organic solvents. In this research, two industrial Kraft lignins derived from softwood and hardwood were treated using different green organic solvents (2-methyl tetrahydrofuran, tetrahydrofuran, 1-methoxy-2-propanol, and acetone), measuring the soluble and insoluble content to determine the mass balance, and the solubility was evaluated using Hansen parameters and FTIR. The results showed that both lignins were more soluble in tetrahydrofuran and 1-methoxy-2-propanol. Also, tetrahydrofuran performed better than the 2-methyl tetrahydrofuran, which is considered the green alternative. The reason can be explained using the Hansen solubility parameters. Moreover, the solubilised fractions showed similar FTIR spectra. The same is the case for the insoluble parts. In conclusion, the two lignins studied showed different solubilities in absolute values in organic solvents, but the trends were similar. [ABSTRACT FROM AUTHOR]

The supermolecule-mediated method is employed to prepare an organic molecule aggregate (OMA) precursor called MCAL in which the dopant agent (melamine-cyanuric acid supramolecular (MCA)) and biomass molecule (alkali lignin (AL)) are uniformly mixed. Direct pyrolysis of OMA yields lignin-derived highly nitrogen-doped turbine-like carbon (LNTC), which serves as a high-performance anode for potassium-ion capacitors. [Display omitted] Potassium-ion hybrid capacitors (PIHCs) represent a burgeoning class of electrochemical energy storage devices characterized by their remarkable energy and power densities. Utilizing amorphous carbon derived from sustainable biomass presents an economical and environmentally friendly option for anode material in high-rate potassium-ion storage applications. Nevertheless, the potassium-ion storage capacity of most biomass-derived carbon materials remains modest. Addressing this challenge, nitrogen doping engineering and the design of distinctive nanostructures emerge as effective strategies for enhancing the electrochemical performance of amorphous carbon anodes. Developing highly nitrogen-doped nanocarbon materials is a challenging task because most lignocellulosic biomasses lack nitrogen functional groups. In this work, we propose a general strategy for directly carbonizing supermolecule-mediated lignin organic molecular aggregate (OMA) to prepare highly nitrogen-doped biomass-derived nanocarbon. We obtained lignin-derived, highly nitrogen-doped turbine-like carbon (LNTC). Featuring a three-dimensional turbine-like structure composed of amorphous, thin carbon nanosheets, LNTC demonstrated a capacity of 377 mAh g−1 when used as the anode for PIHCs. This work also provides a new synthesis method for preparing highly nitrogen-doped nanocarbon materials derived from biomass. [ABSTRACT FROM AUTHOR]

Biofuel production from lignocellulose feedstocks is sustainable and environmentally friendly. However, the lignocellulosic pretreatment could produce fermentation inhibitors causing multiple stresses and low yield. Therefore, the engineering construction of highly resistant microorganisms is greatly significant. In this study, a composite functional chimeric cellulosome equipped with laccase, versatile peroxidase, and lytic polysaccharide monooxygenase was riveted on the surface of Saccharomyces cerevisiae to construct a novel yeast strain YI/LVP for synergistic lignin degradation and cellulosic ethanol production. The assembly of cellulosome was assayed by immunofluorescence microscopy and flow cytometry. During the whole process of fermentation, the maximum ethanol concentration and cellulose conversion of engineering strain YI/LVP reached 8.68 g/L and 83.41%, respectively. The results proved the availability of artificial chimeric cellulosome containing lignin-degradation enzymes for cellulosic ethanol production. The purpose of the study was to improve the inhibitor tolerance and fermentation performance of S. cerevisiae through the construction and optimization of a synergistic lignin-degrading enzyme system based on cellulosome. [ABSTRACT FROM AUTHOR]

Derived from lignocellulosic biomass, sustainable hard carbon has emerged as a promising low-cost anode material for sodium-ion batteries (SIBs). However, the intricate formation process of the hard carbon microstructure remains unclear. This study investigates the structural differences and pyrolysis behaviors of pine lignin and its graded variants obtained through a lignin molecular sieving engineering strategy. Moreover, it delves into the relationship between the microstructure of lignin-derived hard carbon and its sodium-ion storage characteristics. Pristine pine lignin, along with ethanol-isolated lignin, acetone-isolated lignin, and residual lignin, serves as a precursor for synthesizing hard carbon materials. Quantitative analysis via31P NMR spectroscopy reveals the highest content of polar functional groups in ethanol-isolated lignin. Interestingly, hard carbon derived from ethanol-isolated lignin exhibits the smallest closed pore volume, leading to the lowest plateau capacity of sodium-ion storage. Conversely, hard carbon derived from acetone-dissolved lignin displays the highest plateau capacity owing to its largest closed pore volume formed in the carbonization process. The origin of open and closed pore structures of hard carbons is thoroughly analyzed. [ABSTRACT FROM AUTHOR]

Miscanthus is a perennial grass suitable for the production of lignocellulosic biomass on marginal lands. The effects of salt stress on Miscanthus cell wall composition and its consequences on biomass quality have nonetheless received relatively little attention. In this study, we investigated how exposure to moderate (100 mM NaCl) or severe (200 mM NaCl) saline growing conditions altered the composition of both primary and secondary cell wall components in the stems of 15 Miscanthus sinensis genotypes. The exposure to stress drastically impacted biomass yield and cell wall composition in terms of content and structural features. In general, the observed compositional changes were more pronounced under severe stress conditions and were more apparent in genotypes with a higher sensitivity towards stress. Besides a severely reduced cellulose content, salt stress led to increased pectin content, presumably in the form of highly branched rhamnogalacturonan type I. Although salt stress had a limited effect on the total lignin content, the acid‐soluble lignin content was strongly increased in the most sensitive genotypes. This effect was also reflected in substantially altered lignin structures and led to a markedly reduced incorporation of syringyl subunits and p‐coumaric acid moieties. Interestingly, plants that were allowed a recovery period after stress ultimately had a reduced lignin content compared to those continuously grown under control conditions. In addition, the salt stress‐induced cell wall alterations contributed to an improved enzymatic saccharification efficiency. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass represents an excellent alternative to fossil fuels in terms of both energy production and raw material usage for a plethora of daily-use products. Organosolv pretreatment is a fractionation technique able to separate lignocellulosic biomass into individual streams of cellulose, hemicellulose, and lignin under controlled conditions. Sawdust, the by-product of sawmill processing of Picea abies wood, was the subject of our investigation in this work. The aim was to evaluate the effects of different parameters of the organosolv process of spruce sawdust on the yield of components and how this affects the enzymatic saccharification of cellulose. Sixteen distinct pretreatments were performed with ethanol concentrations of 50 and 60% v/v at 180 and 200 °C for 15 and 30 min. Half of the pretreatments contained 1% sulfuric acid as a catalyst, while the other half were acid-free. Thereafter, the effects of different variables on the yield of products were assessed and compared to determine the ideal pretreatment condition. The results showed that cellulose-rich pulps, with cellulose content as high as 55% were generated from an initial mass of 37.7% spruce sawdust with the reactor operating at 180 °C for 30 min using 60% ethanol and 1% sulfuric acid. With the pretreatments performed with the catalyst at 200 °C, hemicellulose was almost entirely removed from the pulps obtained. The recovered hemicellulose fraction was composed mainly of monomers achieving up to 10 g/100 g of biomass. Delignification values of up to 65.7% were achieved with this pretreatment technique. Fractionated lignin presented low levels of sugar and ashes contamination, with values as low as 1.29% w/w. Enzymatic saccharification of the pretreated pulps yielded 78% cellulose hydrolysis, with glucose release higher than 0.54 g/g of biomass, indicating the potential of the pulps to be applied in a fermentation process. [ABSTRACT FROM AUTHOR]

This research used wheat, rice, and corn residue as a substrate for biogas production. Due to the high amount of lignin in all three substrates (> 9.9) and to increase the degradability of these substrates, an ultrasonic pretreatment with a power of 150 W at 15 min was used before initiating the enzymatic digestion process. Some physical and chemical properties, including solid and volatile particles and contents of lignin, cellulose and hemicellulose, were measured before and after digesting the substances; in addition, the biogas compounds, including hydrogen methane, hydrogen sulfide and carbon monoxide were measured during digestion. The metabolic pathways of converting glucose as the main constituent of all three waste types into biogas were studied to determine the factors affecting biogas compounds. The results showed that the use of ultrasonic pretreatment in all three wastes increased the breakdown of lignin structures, which decreased the content of these structures in the feedstock compared to the substrate. The amount of solid and volatile particles of the feedstock obtained from the substrate of wheat residue was 35.1% and 95.3%, respectively, which was more than that of the other substrates. The highest amounts of reduction of solid particles (19.6%), volatile particles (18%), cellulose (12.6%), hemicellulose (4.4%) and lignin (3.6%) were related to the feedstock obtained from wheat residue. Analyses of biogas compounds showed the highest biohydrogen production obtained for wheat substrate (ppm 18000), but its biomethane production was lower than the other substrates. The highest amounts of biohydrogen production of all the substrates occurred after seven days, related to the butyrate acidification stage. With increasing digestion time, hydrogen production decreased while the other biogas compounds increased. One of the probable reasons was the consumption of hydrogen produced in the stages of hydrolysis, acidification and acetate formation in the stages of alcoholization and methanation. The highest amount of hydrogen production was related to the butyrate and acetate formation stages. The higher biohydrogen production by wheat residue is most likely due to its high volume of volatile, hydrocarbon and hemicellulose compounds. At the same time, the low production of hydrogen by corn residue was due to driving the reactions towards the production of ethanol and consuming hydrogen. [ABSTRACT FROM AUTHOR]

Lignin, a crucial component of lignocellulosic biomass, holds immense promise for advancing biorefineries and producing sustainable energy alternatives. This study engineered a CN/rGO/BMO (2 : 1) heterojunction photocatalyst with varying Pd NP loading to selectively target the hydrogenolysis of challenging C–O ether bonds in lignin model compounds. Specific focus was on β-O-4, α-O-4, and the formidable 4-O-5 linkages. The 4-O-5 linkage, due to its high dissociation energy, poses a significant challenge. Electrochemical and spectral analyses unveiled improvements in charge separation, leading to delayed recombination of charge carriers in the heterojunction photocatalyst. Decorating the heterojunction with Pd NPs exhibited an elevated work function and a low Fermi energy level, facilitating the accommodation of photogenerated electrons and enabling efficient H2 dissociation. Such enhancement facilitated the cleavage of all three linkages, including the resistant 4-O-5 bonds under ambient conditions. The photocatalyst exhibited effective cleavage, yielding aromatic (toluene, phenol, ethylbenzene) and aliphatic (cyclohexane, ethylcyclohexane) products. Selectivity modulation was achieved by adjusting the time, hydrogen pressure, and Pd loading. Furthermore, this photocatalytic approach successfully transformed simulated lignin bio-oil containing all three linkages into valuable monomers. The alcoholic solvents efficiently harnessed photogenerated holes and prevented electron–hole recombination. The photocatalyst also demonstrated the capability to produce monomers from the native lignin extracted from teak wood sawdust. Emphasizing the focus on the reaction pathway and mechanism, scavenging studies and analyses were conducted, including UPS and VBXPS, to establish the Z-scheme charge transfer mechanism within the heterojunction. These findings provide a sustainable and efficient pathway for lignin valorisation in biorefineries, significantly contributing to the advancement of green fuels and aligning with the principles of green chemistry. [ABSTRACT FROM AUTHOR]

The reductive catalytic fractionation (RCF) of lignocellulose, considering lignin valorization at design time, has demonstrated the entire utilization of all lignocellulose components; however, such processes always require catalysts based on precious metals or high‐loaded nonprecious metals. Herein, the study develops an ultra‐low loaded, atomically dispersed cobalt catalyst, which displays an exceptional performance in the RCF of lignocellulose. An approximately theoretical maximum yield of phenolic monomers (48.3 wt.%) from lignin is realized, rivaling precious metal catalysts. High selectivity toward 4‐propyl‐substituted guaiacol/syringol facilitates their purification and follows syntheses of highly adhesive polyesters. Lignin nanoparticles (LNPs) are generated by simple treatment of the obtained phenolic dimers and oligomers. RCF‐resulted carbohydrate pulp are more obedient to enzymatic hydrolysis. Experimental studies on lignin model compounds reveal the concerted cleavage of Cα–O and Cβ–O pathway for the rupture of β‐O‐4 structure. Overall, the approach involves valorizing products derived from lignin biopolymer, providing the opportunity for the comprehensive utilization of all components within lignocellulose. [ABSTRACT FROM AUTHOR]

Biorefining of lignocellulosic biomass via a lignin first approach delivers a range of products with high oxygen content. Besides pulp, a lignin oil rich in guaiacols and syringols is obtained bearing multiple C(aryl)–OH and C(aryl)–OMe groups, typically named phenolics. Similarly, technical lignin can be used but is generally more difficult to process providing lower yields of monomers. Removal of the hydroxy and methoxy groups in these oxygenated arenes is challenging due to the inherently strong C–O bonds, in addition to the steric and electronic deactivation by adjacent –OH or –OMe groups. Moreover, chemoselective removal of a specific group in the presence of other similar functionalities is non-trivial. Other side-reactions such as ring saturation and transalkylation further complicate the desired reduction process. In this overview, three different selective reduction reactions are considered. Complete hydrodeoxygenation removes both hydroxy and methoxy groups resulting in benzene and alkylated derivatives (BTX type products) which is often complicated by overreduction of the arene ring. Hydrodemethoxylation selectively removes methoxy groups in the presence of hydroxy groups leading to phenol products, while hydrodehydroxylation only removes hydroxy groups without cleavage of methoxy groups giving anisole products. Instead of defunctionalization via reduction transformation of C(aryl)–OH, albeit via an initial derivatization into C(aryl)–OX, into other functionalities is possible and also discussed. In addition to methods applying guaiacols and syringols present in lignin oil as model substrates, special attention is given to methods using mixtures of these compounds obtained from wood/technical lignin. Finally, other important aspects of C–O bond activation with respect to green chemistry are discussed. [ABSTRACT FROM AUTHOR]

Recently, the ambient drying method for the preparation of xerogels has attracted great attention due to its low cost and high drying efficiency. However, the strong capillary forces existing during ambient drying cause severe shrinkage or even collapse of the aerogels (called xerogels). Although chemical crosslinking or displacement of water by organic solvents have been tried to solve the problem, extensive usage of chemicals and time-consuming displacement processes seem to be environmentally unfriendly and complex. Herein, we reported a green and efficient method for the preparation of a lignocellulosic xerogel. The xerogel was fabricated by alkali freezing of unbleached eucalyptus fibers followed by water washing and ambient drying. The alkali freezing promoted fiber swelling and enhanced the hydrogen bonds among the fibers, resulting in the gelation of lignocellulosic fibers. In particular, the residual lignin in the fibers reduced the capillary force during the drying process. The resulting lignocellulosic xerogel achieved a low shrinkage rate (27.50%), low density (0.039 g cm−3 ), high porosity (97.57%), and excellent mechanical strength (782.23 kPa) as well as environmental stability, and low thermal conductivity (44.76 mW m−1 K−1 ). Similarly structured xerogels could be generated using recycled NaOH solution. This technique was suitable for production using various kinds of plant fibers, which shows its great scalable production prospects. [ABSTRACT FROM AUTHOR]

Lignocellulose biorefining has great potential to replace the use of petrochemical resources in the production of fuels and chemicals. However, the full use of lignocellulose, which is depolymerized to yield mainly glucose, xylose, and lignin-derived phenolics, remains challenging. Here, we developed a glucose–xylose–phenolics (GXP) system to fully use lignocellulose for the production of L-tyrosine and its analogues in minimal medium. First, we engineered an Escherichia coli–Escherichia coli consortium carrying a CRISPR/dCas9 interference system to simultaneously use glucose and xylose to support cell growth and produce pyruvate, obtaining 34.3 g L−1 pyruvate with a yield of 0.68 g g−1 sugar. Then, we introduced tyrosine phenol lyase and other biocatalytic enzymes into this consortium to generate the GXP system, which could convert pyruvate and lignin-derived phenolics to L-tyrosine and its analogues. Using this GXP system, 20.8 g L−1L-tyrosine was produced from 12.5 g L−1 phenol with a yield of 86.4%. Using the hydrolysate of the raw material sorghum pith, 0.94 g L−1L-tyrosine was produced from 0.96 g L−1p-coumaric acid with a yield of 88.7%, and 8.1 g L−1 pyruvate remained, corresponding to an overall yield of 0.163 g product g−1 sorghum pith. The development of this GXP system illustrates a strategy for fully utilizing lignocellulosic biomass for the synthesis of value-added chemicals. [ABSTRACT FROM AUTHOR]

In the current study, we compared the production of extracellular lignocellulose degrading enzymes and bioethanol from the spent mushroom substrate (SMS) of Calocybe indica and Volvariella volvacea. From SMS at different stages of the mushroom development cycle, ligninolytic and hydrolytic enzymes were analysed. The activities of lignin-degrading enzymes, including lignin peroxidase (LiP), laccase, and manganese peroxidase (MnP) were maximal in the spawn run and primordial stages, while hydrolytic enzymes including xylanase, cellobiohydrolase (CBH), and carboxymethyl cellulase (CMCase) showed higher activity during fruiting bodies development and at the end of the mushroom growth cycle. SMS of V. volvacea showed relatively lower ligninase activity than the SMS of C. indica, but had the maximum activity of hydrolytic enzymes. The enzyme was precipitated with acetone and further purified with the DEAE cellulose column. The maximum yield of reducing sugars was obtained after hydrolysis of NaOH (0.5 M) pretreated SMS with a cocktail of partially purified enzymes (50% v/v). After enzymatic hydrolysis, the total reducing sugars were 18.68 ± 0.34 g/l (SMS of C. indica) and 20.02 ± 0.87 g/l (SMS of V. volvacea). We observed the highest fermentation efficiency and ethanol productivity (54.25%, 0.12 g/l h) obtained from SMS hydrolysate of V. volvacea after 48 h at 30 ± 2 °C, using co-culture of Saccharomyces cerevisiae MTCC 11,815 and Pachysolen tannophilus MTCC 1077. [ABSTRACT FROM AUTHOR]

Interactions of cellulose- and lignin-derived intermediates have been well documented during pyrolysis of lignocellulosic biomass. The reaction network for the interactions is rather complex, as cellulose-derived volatiles could interact/react with not only lignin-derived volatiles but also lignin-derived char and vice versa. To probe specifically the impacts of cellulose-derived volatiles on the lignin-derived char or the opposite, herein the sequential pyrolysis was performed by arranging cellulose in the upper bed with lignin in the lower bed or lignin above with cellulose below at 350 and 650 °C, respectively. The results indicated that the sequential pyrolysis of cellulose→lignin or lignin→cellulose at 350 °C induced increased char yield from formation of carbonaceous deposits via volatiles-char interactions. Compared with the lignin-derived volatiles, the cellulose-derived volatiles, especially aldehyde fractions, were more reactive towards the lignin-derived char at 350 °C, forming oxygen-rich lignin-derived char with a higher yield, an abundance of aliphatic structures and consequently lower thermal stability. In sequential pyrolysis of lignin→cellulose, more aromatics-rich species were deposited on cellulose-derived char, but the lignin-derived volatiles were less reactive for enhancing the char yield. At 650 °C, instead of polymerisation of the volatiles on the char, either the cellulose- or lignin-derived char catalyzed the cracking of the counterpart volatiles to remove the aliphatic functionalities, which made the char more aromatic and thermally more stable. [ABSTRACT FROM AUTHOR]

Background: Lignin and xylan are important determinants of cell wall structure and lignocellulosic biomass digestibility. Genetic manipulations that individually modify either lignin or xylan structure improve polysaccharide digestibility. However, the effects of their simultaneous modifications have not been explored in a similar context. Here, both individual and combinatorial modification in xylan and lignin was studied by analysing the effect on plant cell wall properties, biotic stress responses and integrity sensing. Results: Arabidopsis plant co-harbouring mutation in FERULATE 5-HYDROXYLASE (F5H) and overexpressing Aspergillus niger acetyl xylan esterase (35S:AnAXE1) were generated and displayed normal growth attributes with intact xylem architecture. This fah1-2/35S:AnAXE1 cross was named as hyper G lignin and hypoacetylated (HrGHypAc) line. The HrGHypAc plants showed increased crystalline cellulose content with enhanced digestibility after chemical and enzymatic pre-treatment. Moreover, both parents and HrGHypAc without and after pre-treating with glucuronyl esterase and alpha glucuronidase exhibited an increase in xylose release after xylanase digestion as compared to wild type. The de-pectinated fraction in HrGHypAc displayed elevated levels of xylan and cellulose. Furthermore, the transcriptomic analysis revealed differential expression in cell wall biosynthetic, transcription factors and wall-associated kinases genes implying the role of lignin and xylan modification on cellular regulatory processes. Conclusions: Simultaneous modification in xylan and lignin enhances cellulose content with improved saccharification efficiency. These modifications loosen cell wall complexity and hence resulted in enhanced xylose and xylobiose release with or without pretreatment after xylanase digestion in both parent and HrGHypAc. This study also revealed that the disruption of xylan and lignin structure is possible without compromising either growth and development or defense responses against Pseudomonas syringae infection. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs) and ionic liquids (ILs) are potential solvents for lignocellulosic biomass fractionation. In this study, the rice straw pretreatment efficiency of four cholinium-based solvents (DESs and ILs) prepared from the same sources (lactic acid and lysine) were comparatively investigated at 110 °C for 4 h. The lignin removal rate correlated well with the saccharification efficiency of the pulps. Quantum chemical (QC) calculations and molecular dynamics (MD) simulations focused on the microscopic structure and non-covalent interactions of the solvents and lignin model molecules (guaiacylglycerol-β-guaiacyl ether, GG) were carried out, and the results indicate that anions of the solvent systems play a leading role (through strong hydrogen bonds or electrostatic interactions) in establishing interactions with GG, supported by cations (via van der Waals interactions). There were clear positive relationships between the total interaction energies (IEs) and lignin removal, cellulose digestibility and glucose yields. In particular, [Ch][Lys] with a low self-interaction energy is able to free some active sites to form strong hydrogen bonds and electrostatic interactions with lignin, thus resulting in lignin dissolution and excellent delignification. For cholinium cations, an ideal partner system provides low self-IEs for solvent molecules and strong IEs between solvents and lignin, which are determined by the type and number of functional groups and the alkyl chain length of the partner components. This work provides ideas about tailoring suitable partner systems for cholinium cations to build solvents for efficient biomass deconstruction. [ABSTRACT FROM AUTHOR]

Glucuronoyl esterases (GEs) are serine-type hydrolase enzymes belonging to carbohydrate esterase family 15 (CE15), and they play a central role in the reduction of recalcitrance in plant cell walls by cleaving ester linkages between glucuronoxylan and lignin in lignocellulose. Recent studies have suggested that bacterial CE15 enzymes are more heterogeneous in terms of sequence, structure, and substrate preferences than their fungal counterparts. However, the sequence space of bacterial GEs has still not been fully explored, and further studies on diverse enzymes could provide novel insights into new catalysts of biotechnological interest. To expand our knowledge on this family of enzymes, we investigated three unique CE15 members encoded by Dyadobacter fermentans NS114T, a Gram-negative bacterium found endophytically in maize/corn (Zea mays). The enzymes are dissimilar, sharing ≤ 39% sequence identity to each other‚ and were considerably different in their activities towards synthetic substrates. Combined analysis of their primary sequences and structural predictions aided in establishing hypotheses regarding specificity determinants within CE15, and these were tested using enzyme variants attempting to shift the activity profiles. Together, the results expand our existing knowledge of CE15, shed light into the molecular determinants defining specificity, and support the recent thesis that diverse GEs encoded by a single microorganism may have evolved to fulfil different physiological functions. Key points: • D. fermentans encodes three CE15 enzymes with diverse sequences and specificities • The Region 2 inserts in bacterial GEs may directly influence enzyme activity • Rational amino acid substitutions improved the poor activity of the DfCE15A enzyme [ABSTRACT FROM AUTHOR]

Background: The 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. Results: The 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. Conclusions: The 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. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs) are widely used as recyclable green solvents for the separation of lignin from lignocellulosic biomass. However, the poor permeability of DES solution limits the green advancement of separation systems. In addition, lignin fragment molecules are susceptible to repolymerization reactions during separation, resulting in reduced lignin reactivity. In this study, a DES consisting of choline chloride (ChCl) as a hydrogen acceptor, 5-sulfosalicylic acid (5Saa) as a hydrogen donor, and a certain amount of γ-valerolactone (GVL) as an additive was designed. The system not only efficiently fractionated lignin from poplar (71.35%), but also selectively retained almost complete cellulose (retention 92.87%) under the optimal fractionation (ChCl/5Saa/GVL molar ratio 1/4/15, temperature 120 °C, time 3.0 h). Pre-crushing processing of raw materials was avoided as the new DES solution has stronger permeability compared to the previous DES solution. Selective deconstruction of lignocellulose was achieved due to a strong hydrogen network structure. The lignin fragments were effectively dissolved. The results showed that the stability of the carbo-positive active intermediates was enhanced by ChCl–5Saa/GVL. Lignin with a low molecular weight (2305 g mol−1), high purity (98.77%) and high total phenolic hydroxyl content (6.92 mmol g−1) was obtained. Homogeneous lignin nanoparticles (LNPs) were prepared with an average particle size of 23 nm. LNPs had high dispersion stability and excellent UV shielding properties. The green advancement of the new DES has been significantly improved and the efficient fractionation of high-value lignin was realized. [ABSTRACT FROM AUTHOR]

Lignins, heterogeneous assemblies of polyphenolic oligomers present in lignocellulosic plant biomass, are valorized mainly by combustion because of their low solubility in commonly used solvents. However, in addition to antioxidant, anti‐UV and antimicrobial properties, and marked interfacial properties are part of lignins physicochemical properties, thus making them good candidates for sustainable colloids. It is hypothesized that lignins solubility and emulsifying performances could be modulated by fractionation, functionalization, and formulation strategies. The importance of the solvent, and of the pH on lignins solubilization in aqueous phase was investigated. Accordingly, simple O/W emulsions stabilized by different lignins were designed and characterized. The whole results demonstrated that lignins solubility in water can be optimized using appropriate co‐solvent and pH readjustment resulting in a homogeneous dispersion with only 7.2 ± 1.8% wt/wt of insoluble lignins. Both fractionation and biocatalytic modification of lignins allowed increasing stabilization of the oil–water interface by limiting coalescence (23%–24% of relative increase of the D90) compared with non‐fractionated lignins (32%), thus advocating their potential use as multifunctional emulsion stabilizers. As a result, a direct link between the molar mass profile of lignins and their ability to stabilize the oil–water interface as well as to reduce emulsion's sedimentation could be established. [ABSTRACT FROM AUTHOR]

Lignin is the natural binder in wood and lignocellulosic plants and is regarded as the main natural and renewable source of phenolic compounds. Its incorporation in the composition of fiberboards will enhance both the environmental performance of the panels and the complex use of natural resources. In recent years, the increased valorization of hydrolysis lignin in value-added applications, including adhesives for bonding fiberboard panels, has gained significant research interest. Markedly, a major drawback is the retention of lignin in the pulp until the hot-pressing process. This problem could be overcome by using a small content of phenol–formaldehyde (PF) resin in the adhesive mixture as an auxiliary binder. The aim of this research work was to investigate and evaluate the effect of the hot-pressing temperature, varied from 150 °C to 200 °C, in a modified hot-press cycle on the main physical and mechanical properties of fiberboard panels bonded with unmodified technical hydrolysis lignin (THL) as the main binder and PF resin as an auxiliary one. It was found that panels with very good mechanical properties can be fabricated even at a hot-pressing temperature of 160 °C, while to provide the panels with satisfactory waterproof properties, it is necessary to have a hot-pressing temperature of at least 190 °C. [ABSTRACT FROM AUTHOR]

Second-generation biofuels from lignocellulosic biomass remain critical and require several challenges due to lignin compounds' inefficient degradation and recalcitrate characteristics. In this regard, this study focuses on enzymatic technology as a promising treatment that is beneficial in breaking down the biomass's hemicellulose and cellulosic parts. Thermostable bacterial species owe thermostable enzymes that are able to degrade complex carbohydrate compounds and produce efficient hydrogen production. The present study investigates the direct utilization of ligninolytic enzymes such as cellulase and xylanase derived from the hyperthermophilic bacteria Thermotoga maritima (ATCC 43589 strain). The results show that xylanase and cellulase enzymes extracted from Thermotoga maritima could depolymerize the lignin bonds of corn stover substrate and release monomers such as Galactose in the media. In conclusion, this study can open a new advanced research window on directly applying a hyperthermophilic consortium of enzymes capable of hydrolyzing lignocellulose material toward hydrogen production. [ABSTRACT FROM AUTHOR]

The glass transition temperatures (Tg) of native, residual, and technical lignins are important to lignocellulose pulping, pulp processing and side stream utilization; however, how the structural changes from native to residual and technical lignin influences Tg has proven difficult to elucidate. Since the Tg of macromolecules is greatly influenced by the molecular weight, low-molecular-weight fractions, such as milled wood lignin (MWL), are poor representatives of lignin in the cell wall. To circumvent this problem, lignins of both high yield and purity were isolated from Norway spruce and softwood kraft pulp using the enzymatic mild acidolysis lignin (EMAL) protocol. Technical softwood kraft lignin was also fractionated into groups of different molecular weights, to acquire lignin that spanned over a wide molecular-weight range. A powder sample holder for dynamic mechanical analysis (DMA), was used to determine the Tg of lignins, for which calorimetric methods were not sensitive enough. The Tgs of EMAL were found to be closer to their in situ counterparts than MWL. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass from crop residues is an abundant and inexpensive resource that can be converted into high-value platform chemicals. An effective approach is a two-step and "lignin-first" process, utilizing ionic liquid pretreatment followed by ethanol–water liquefaction. In this work, the corn stalk (CS) was pretreated with the ionic liquid [B2-HEA][OAc] to remove lignin. The optimal pretreatment conditions were determined to be 130 °C for 5 h at a liquid–solid ratio of 10:1, achieving delignification of 85.88 wt% while recovering 52.22 wt% of cellulose and 30.18 wt% of hemicellulose. The pretreated CS was then converted into ethyl levulinate (EL) via ethanol–water liquefaction at 190 °C for 90 min. This resulted in a maximum EL yield of 39.93 wt%. Furthermore, the structural and thermal analyses via XRD, FTIR, TGA and SEM revealed the effective lignin removal and increased cellulose accessibility in the pretreated CS, as well as significant changes in chemical structure following liquefaction. Compared to the original CS, the crystallinity index of pretreated CS increased from 66.85% to 74.87%. The combination of ionic liquid pretreatment and ethanol–water liquefaction serves as an efficient process to convert the lignocellulosic residue corn stalk into value-added platform chemicals. [ABSTRACT FROM AUTHOR]

In this perspective, we present an overview of the research and advancement of lignocellulose-derived hard carbon anodes and their pivotal role in the commercialization of sodium-ion batteries. Hard carbon anodes, sourced from lignocellulosic biomasses, exhibit considerable promise due to their widespread availability, economical viability, and environmentally friendly attributes with zero carbon-dioxide emissions. Given the intricate compositions and composite nature of lignocellulosic materials, it becomes imperative to prioritize factors crucial for the fabrication of hard carbon anodes that exhibit enhanced sodium-ion storage capabilities. Thus, our study offers an extensive overview of the structure and performance nuances of hard carbon anodes derived from cellulose, hemicellulose, and lignin. Furthermore, it delves into the fundamental principles governing synthesis methodologies and confronts the challenges inherent in producing lignocellulose-derived hard carbon anodes tailored specifically for sodium-ion batteries. Highlights: • Lignocellulose is a promising low-cost precursor for the hard carbon anodes in sodium-ion batteries. • Chemical, crystalline, components, and multi-dimensional structures of lignocellulose influence the structure and performance of hard carbon anodes. • Engineering methodologies tuning the microstructures of lignocellulose could change the intrinsic structure and performances of hard carbon anodes. • New methods also need to consider the principles of green chemistry and sustainable development. [ABSTRACT FROM AUTHOR]

This study shows a functional deep eutectic solvent (DES) employing choline chloride (ChCl) and glyoxylic acid (GA) for lignocellulose fractionation. This DES exhibited a higher pretreatment efficiency (92.15%) than that composed of ChCl and lactic acid (10.36%). Molecular dynamic (MD) simulations indicated that the ChCl : GA DES showed a higher total binding energy (ΔE) with lignin than the ChCl : LA DES, resulting in a higher dissolution of lignin. GA prevented lignin condensation during pretreatment. The stabilized lignin containing 69.39% β-O-4 linkages can be used for phenolic monomer production with a bio-oil yield of 59.60% and lignin-based sunscreen preparation with a SPF of 58.46. The cellulose residues with a mild pretreatment severity exhibited a high enzymatic saccharification yield of 91.99%. Meanwhile, an esterification reaction occurred between cellulose and GA during pretreatment. The inhibition of enzymatic hydrolysis and microbial growth enables the use of functional cellulose to produce antibacterial paper. Furthermore, 96.80% of the DES could be easily recycled and reused for biorefinery purposes. [ABSTRACT FROM AUTHOR]

Biomass-derived solvents have been proposed as a novel pathway in biorefining for the realization of biofuels and bioproducts derived from lignocellulosic biomass. Cyrene derived from cellulose has recently been shown to have a high potential as a green organic solvent for pretreating poplar biomass. However, due to its high dynamic viscosity nature, high Cyrene concentration could cause negative effects on the sugar release of the pretreated biomass as well as driving up the operational cost of the lignin recovery. In this study, we combine experimental and computational approaches to examine the impact of Cyrene pretreatment with reduced Cyrene concentration under mild conditions on switchgrass lignin. Our experimental studies indicated correlation between pretreatment condition and recovery and structure modification of lignin. Switchgrass lignin extracted by Cyrene pretreatment possessed high preservation of β-O-4 ether inter-unit linkage, which could provide versatility in the integration of downstream lignin valorization into the modern biorefinery industries. Molecular modeling examining the solvation of switchgrass lignin polymer and the disaggregation of low-molecular weight lignin aggregates under pretreatment conditions indicated that a preferential interaction exists between Cyrene and lignin, which likely drives lignin release, and that the disruption of inter-lignin contacts can be modulated as a non-monotonic function of Cyrene : water ratio. Further, while Cyrene–lignin interactions permit the solubilization of lignin, simulations with proxy reactive-species reveal that changes to the diffusion of these reactive proxies and their localization near linkage sites under Cyrene conditions may inhibit chemical processes. The results indicated that loss of pretreatment efficacy caused by low Cyrene concentration could be compensated by prolonged pretreatment time and high catalyst dosage. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs) are a novel class of solvents that can be used to fractionate biomass compounds. However, their sustainability depends strongly on their recyclability. In previous research, it was seen that membrane filtration with commercial cellulose membranes (RC70PP and Ultracel 5 kDa) might be a solution for purification of spent deep eutectic solvent (DES) that has been used in lignin extraction (Choline Chloride: Lactic Acid 1:10 molar ratio) from woody biomass. This DES is, however, very acidic (pH 1.3), which can have detrimental effects on the longevity of the membrane. In a previous study, the time that the membranes were exposed to the spent DES was relatively short. This study aims to increase knowledge of how cellulose membranes withstand spent DES over longer time periods of up to 8 weeks. The results show that cellulose membranes are quite stable under exposure to spent DES in terms of pure water flux and PEG retention for up to 4 weeks. After 8 weeks, the RC70PP membrane demonstrated an increase in pure water permeability of 45% and a noticeable decrease in PEG retention. Surface characterization revealed, however, that the chemical structure of the cellulose membranes changed already after 2 weeks of exposure prior to any changes in pure water permeability were observed. Experimentally revealed esterification of cellulose membrane by Lactic Acid of DES led to more negative charge of the exposed samples compared to their references. This esterification was accompanied by hydrolysis that removed amorphous parts and increased the crystallinity of the membrane. [ABSTRACT FROM AUTHOR]

Glycerol-assisted instant catapult steam explosion (ICSE) of lignocellulose is an effective pretreatment method for enhancing sugar production compared to glycerol-free ICSE. In this study, glycerol-assisted ICSE of corn stover was studied in order to understand the reaction mechanisms and further optimize the process. Results showed that water extraction of corn stover prior to ICSE reduced pseudo-lignin formation. The combination of water extraction and glycerol-assisted ICSE led to the formation of lignin with a lower molecular weight (Mw) of 2851 g/mol than 3521 g/mole of that from the combination of water extraction and glycerol-free ICSE. 1H-13C NMR analysis revealed that glycerol likely reacted with lignin carboxylic OHs through esterification while etherification of aliphatic OHs was not observed in ICSE. These lignin analyses indicated that glycerol protected lignin from condensation/repolymerization during glycerol-assisted ICSE. Enzymatic hydrolysis results showed that without water extraction increasing glycerol usage from 0.2 kg/kg stover to 0.4 kg/kg stover improved glucan digestibility to 78% but further increase to 0.5 kg/kg stover reduced glucan digestibility. In addition, at the glycerol usage of 0.2–0.4 kg/kg stover, washing of pretreated stover for removal of glycerol and other biomass-derived compounds did not improve glucan digestibility compared to unwashed ones. Combination of water extraction and glycerol-assisted ICSE led to a high glucan digestibility of 89.7% and a total glucose yield of 25.5 g glucose/100 g stover, which were 30.1% and 7.5 g/100 g stover higher than those derived from glycerol-free ICSE of stover, respectively. Since glycerol is a low-cost carbon source, the resulting enzymatic hydrolysate that contained both glucose and glycerol may be directly used to produce bioproducts by microbial fermentation. Highlights: Glycerol-assisted ICSE of corn stover improved enzymatic glucose production. Water extraction prior to ICSE further enhanced sugar production. Enzymatic hydrolysis was not affected by glycerol from glycerol-assisted ICSE. Sequential water extraction and ICSE led to a high glucan digestibility of 89.7%. Glycerol likely had a multiple role in ICSE and enzymatic hydrolysis. [ABSTRACT FROM AUTHOR]

Background: EnZolv is a novel enzyme-based, eco-friendly biomass pretreatment process that has shown great potential in the field of textile engineering and biotechnology. It employs laccase from Hexagonia hirta MSF2 and 2% ethanol in the process of delignification. The process is designed to evaluate optimal conditions to remove lignin and other impurities from cotton spinning mill waste (CSMW), without compromising the quality and strength of the fibers. CSMW is a low-cost and readily available source of cellulose, making it an ideal candidate for delignification using EnZolv. By optimizing the pretreatment conditions and harnessing the potential of enzymatic delignification, this research aims to contribute to more sustainable and efficient ways of utilizing lignocellulosic biomass in various industries for the production of biochemical and bioproducts. Results: The present study emphasizes the EnZolv pretreatment in the delignification of cotton spinning mill wastes irrespective of the cellulose content. EnZolv process parameters such as, moisture content, enzyme load, incubation time, incubation temperature, and shaking speed were optimized. Under pre-optimized conditions, the percent lignin reduction was 61.34%, 61.64%, 41.85%, 35.34%, and 35.83% in blowroom droppings (BD), flat strips (FS), lickerin fly (LF), microdust (MD) and comber noils (CN), respectively. Using response surface methodology (RSM), the statistically optimized EnZolv pretreatment conditions showed lignin reduction of 59.16%, 62.88%, 48.26%, 34.64%, and 45.99% in BD, FS, LF, MD, and CN, respectively. Conclusion: Traditional chemical-based pretreatment methods often involve harsh chemicals and high energy consumption, which can have detrimental effects on the environment. In contrast, EnZolv offers a greener approach by utilizing enzymes that are biodegradable and more environmentally friendly. The resulting fibers from EnZolv treatment exhibit improved properties that make them suitable for various applications. Some of the key properties include enhanced cellulose recovery, reduced lignin content, and improved biophysical and structural characteristics. These improvements can contribute to the fiber's performance and processability in different industries and future thrust for the production of cellulose-derived and lignin-derived bioproducts. [ABSTRACT FROM AUTHOR]

Lignocellulose nanofibrils (LCNFs), as an emerging member of the green nanofibril family, have tremendous potential in improving the dispersibility, adsorption and photogenerated carrier separation efficiency of BiOBr because of the combination of the advantages of nanocellulose (NC) and nanolignins. Herein, sulfated lignocellulose nanofibrils (SLCNFs) were obtained from the poplar alkaline peroxide mechanical pulp (APMP) using a deep eutectic solvent (DES) and a mechanical defibrillation strategy, and flower-like BiOBr/SLCNF composites with oxygen vacancies were prepared by in situ synthesis. Due to the well-preserved lignin structure, abundant oxygen-containing functional groups, and the interconnected three-dimensional mesh structure in SLCNFs, the composites exhibited flower-like morphology, good dispersion and excellent adsorption performance after the introduction of SLCNFs. EPR analysis showed that the introduction of SLCNFs increased the number of oxygen vacancies in BiOBr, which improved the visible light absorption and reduced the recombination of photogenerated carriers. In addition, the photocatalytic activity improved with interfacial interaction between BiOBr and SLCNFs promoting the separation of electrons and holes. Therefore, BiOBr/SLCNF can effectively remove RhB in the dynamic continuous process of adsorption enrichment and photocatalytic oxidation. Under visible light, 99% of RhB was degraded within 30 min and 88.5% of tetracycline hydrochloride (TCH) was degraded within 60 min. Importantly, the main active species which removed RhB by BiOBr/SLCNF were ˙O2− and h+, and the BiOBr/SLCNF composites still have good stability and recyclability after 5 times of repeated use. Overall, the BiOBr/SLCNF composite photocatalyst has great potential for the purification of organic wastewater. [ABSTRACT FROM AUTHOR]

Laccases from white-rot fungi catalyze lignin depolymerization, a critical first step to upgrading lignin to valuable biodiesel fuels and chemicals. In this study, a wildtype laccase from the basidiomycete Fomitiporia mediterranea (Fom_lac) and a variant engineered to have a carbohydrate-binding module (Fom_CBM) were studied for their ability to catalyze cleavage of β-O-4′ ether and C–C bonds in phenolic and non-phenolic lignin dimers using a nanostructure-initiator mass spectrometry-based assay. Fom_lac and Fom_CBM catalyze β-O-4′ ether and C–C bond breaking, with higher activity under acidic conditions (pH < 6). The potential of Fom_lac and Fom_CBM to enhance saccharification yields from untreated and ionic liquid pretreated pine was also investigated. Adding Fom_CBM to mixtures of cellulases and hemicellulases improved sugar yields by 140% on untreated pine and 32% on cholinium lysinate pretreated pine when compared to the inclusion of Fom_lac to the same mixtures. Adding either Fom_lac or Fom_CBM to mixtures of cellulases and hemicellulases effectively accelerates enzymatic hydrolysis, demonstrating its potential applications for lignocellulose valorization. We postulate that additional increases in sugar yields for the Fom_CBM enzyme mixtures were due to Fom_CBM being brought more proximal to lignin through binding to either cellulose or lignin itself. [ABSTRACT FROM AUTHOR]

Agave bagasse (AB) is a lignocellulosic biomass with potential to obtain high value-added products such as lignin, microcrystalline cellulose, and polysaccharides that can be used for biofuel production. A Central Composite Design (CCD) was used to evaluate the effect of temperature, thermal treatment time, ethanol concentration, solid/liquid ratio, size particle, and sodium hydroxide concentration on delignification and lignin recovery from AB. In addition, the influence of delignification on the enzymatic hydrolysis using commercial enzymes was determined. This organosolv process allowed a delignification of 91.49% and 76% of the lignin recovery, at 150 °C, 10 min, 40% (v/v) ethanol, solid/liquid ratio of 1:10 g/mL, particle size of 0.5 mm – 1 mm, and 5.5% (w/v) sodium hydroxide. The maximum specific yield of enzymatic hydrolysis (SYEH), under the best conditions for delignification, was of 844.40 ± 9.70 mg total sugars per g of bagasse pretreated with organosolv (BPO), which was 4.42 times higher than the yield obtained from bagasse without pretreatment (BWP). Additionally, the enzymatic hydrolysate of BPO produced 303.62 ± 10.62 NmLCH4/g BPO. Furthermore, an energy recovery efficiency of 64.13 ± 0.9% was obtained for BPO hydrolysate which is 2.60 times higher than that of BWP hydrolysate (24.88 ± 0.92%). In a biorefinery concept, alkaline organosolv pretreatment of AB was highly efficient for lignin production, and improved the enzymatic hydrolysis of polysaccharides, which allowed a higher energy recovery. [ABSTRACT FROM AUTHOR]

The overall purpose of this research work was to apply a microwave-assisted digestion process combined with ethanol organosolv as pretreatment for pistachio shells (PS) and cherry tree pruning (CTP) biomasses for cellulose production. This process would reduce the technical and environmental disadvantages of the accumulation of these agricultural wastes. A central composite design based on the Response Surface Methodology was applied to check the effect of reaction time, temperature, and concentration of ethanol acid solution. Adequate models have been obtained for the contents of cellulose and lignin of the treated solids as well as for solubilized cellulose percentage. Best conditions implied 67% ethanol and 30 min at 150 ∘ C, involving the production of a cellulose-enriched material (81.1% and 90.1% for treated CTP and PS, respectively). Finally, enzymatic hydrolysis of these materials was carried out, reaching glucose concentrations of 70 and 100 kg/m 3 for CTP and PS, resulting in enzymatic hydrolysis yields at 12 h of 97.2% and 76.9%. These high values are one of the main novelties and strengths of this work, as show the ease of the process and can have a beneficial influence on its scale-up, reducing both costs and environmental impact. [ABSTRACT FROM AUTHOR]

Herein, the potential of cotton seed hulls (CSH) as prospective feedstock for producing thermostable and alkaliphilic xylanase by Bacillus pumilus and Bacillus licheniformis during submerged fermentation was demonstrated. Results revealed that CSH predominantly contains holo-cellulose (65.6%), alpha-cellulose (38.8%), hemicelluloses (24.5%), and lignin (18.5%). Compared to the control, 0.5% CSH-supplemented growth media better supported bacterial growth (OD600 nm). Moreover, the extracellular xylanase production increased from 16 h and peaked at 24 h for both B. pumilus (359.2 U/mL) and B. licheniformis (360.8 U/mL). Bacterial xylanase demonstrated considerable stability at a higher temperature (55 °C). Likewise, significant xylanase activity was detected at pH 7.0. However, the enzyme also showed remarkable activity at alkaline pH (At pH 9.0, 84.61%, and 81.89% activity for B. pumilus and B. licheniformis, respectively), indicating alkali tolerance nature. These xylanolytic bacteria potentially depolymerized lignocellulosic fraction with a considerable release of fermentable monosaccharides (1175.10 ± 5.69 and 1278 ± 2.22 ug/mL for B. pumilus and B. lichenformis treated CSH, respectively). The scanning electron micrograph revealed the surface smoothness, cleanliness, and presence of cracks/grooves on xylanase-treated CSH surfaces. FTIR studies confirmed the stretching (at 3318 cm−1 corresponding to the O–H peak of lignin and hemicelluloses) and deformation of inter and intermolecular bonds (at 2950–2850 cm−1 related to aromatic C–H bonds present in cellulose, hemicellulose, and lignin) of lignocellulosic components of CSH. Briefly, the study highlighted the potentiality of CSH as an alternative fermentative substrate for the biosynthesis of xylanase in a biorefinery approach. [ABSTRACT FROM AUTHOR]

Rice hulls have a high-value potential, and the lignocellulose components are underutilized compared to other biomass resources. Pretreatments such as carboxymethylation of the degree of substitutions (DS) are used to prepare lignocellulose nanofibril (LCNF) from desilicated rice hull (DSRH). High-pressure homogenization (HPH) and grinding are used to process nano fibrillation. The composition of LCNF DS of desilicated rice hull was identified using 1H NMR for polysaccharide composition and DS determination, acetone and hot water extraction to evaluate extractives, and Klason lignin for lignin content. LCNF was prepared using various DS from 0.2 until DS 0.4. The results showed that LCNF DS has a more than −30 mV zeta potential, suitable for stable nanoemulsion formulations. The particle size of LCNF DS decreases with an increasing carboxyl content in the hydrogel and an increasing number of passes through grinding and high-pressure homogenization, of which LCNF DS 0.4 had the smallest width and length. Mechanical processes further reduced the size. [ABSTRACT FROM AUTHOR]

This paper focuses on the optimisation of an efficient extraction process for cellulose and lignin from rice straw waste from the Albufera of Valencia using the steam explosion method. This method is particularly pertinent given the environmental and economic challenges posed by the current disposal practices of agricultural waste. The technique comprises a high-temperature cooking stage followed by instantaneous decompression, effectively altering the biomass's physical and chemical properties to enhance its surface area and porosity. Our adaptation of the steam explosion technique specifically addresses the challenges of rice straw waste, marking a significant departure from previous applications. This innovation is crucial in addressing the urgent need for more sustainable waste management practices, as it effectively deconstructs the lignocellulosic matrix of rice straw. This facilitates the selective extraction of cellulose at a 70% efficiency, with a 20% yield and the subsequent recovery of lignin. The results of this study are significant for sustainable biomaterial production, offering novel insights into optimising these crucial biomass components. By refining the process and focusing on critical parameters, our work advances the application of steam explosion methods for agricultural waste, enhancing efficiency and sustainability. By utilising rice straw biowaste, this research not only proposes a solution to a pressing environmental issue but also demonstrates the potential to create new market opportunities, increase the economic value for rice producers, and significantly reduce the environmental footprint of existing waste disposal methods. The holistic and ecological approach of this study underscores the vital need for innovative strategies in agricultural waste management, positioning the valorisation of rice straw waste as a key component in the pursuit of environmental sustainability. [ABSTRACT FROM AUTHOR]

The development of environmentally friendly methods for the valorization of important phenolic platform chemicals originating directly from lignin‐first depolymerization into value‐added N‐chemicals, such as aniline derivatives, is of high industrial interest. In this work, we tackle this challenging transformation by the judicious combination of electrochemical conversion and chemical functionalization steps. In the first step, lignin‐derived para‐substituted guaiacols and syringols undergo an atom‐efficient, room‐temperature anodic oxidation using methanol both as solvent and reagent towards the formation of the corresponding cyclohexadienone derivatives, which are subsequently converted to synthetically challenging ortho‐methoxy substituted anilines by reaction with ethyl glycinate hydrochloride under mild conditions. The developed method was applied to crude lignin depolymerization bio‐oils, derived from reductive catalytic fractionation (RCF) mediated either by copper‐doped porous metal oxide (Cu20PMO) or Ru/C, allowing the selective production of 4‐propanol‐2‐methoxyaniline (1Gb) and 4‐propyl‐2‐methoxyaniline (2Gb), respectively, from pine lignocellulose. Finally, the application of 2Gb was further studied in the synthesis of carbazole 2Gc, a lignin‐derived analogue of biologically active alkaloid murrayafoline A. [ABSTRACT FROM AUTHOR]

Summary: Grass lignocelluloses feature complex compositions and structures. In addition to the presence of conventional lignin units from monolignols, acylated monolignols and flavonoid tricin also incorporate into lignin polymer; moreover, hydroxycinnamates, particularly ferulate, cross‐link arabinoxylan chains with each other and/or with lignin polymers. These structural complexities make grass lignocellulosics difficult to optimize for effective agro‐industrial applications. In the present study, we assess the applications of two engineered monolignol 4‐O‐methyltransferases (MOMTs) in modifying rice lignocellulosic properties. Two MOMTs confer regiospecific para‐methylation of monolignols but with different catalytic preferences. The expression of MOMTs in rice resulted in differential but drastic suppression of lignin deposition, showing more than 50% decrease in guaiacyl lignin and up to an 90% reduction in syringyl lignin in transgenic lines. Moreover, the levels of arabinoxylan‐bound ferulate were reduced by up to 50%, and the levels of tricin in lignin fraction were also substantially reduced. Concomitantly, up to 11 μmol/g of the methanol‐extractable 4‐O‐methylated ferulic acid and 5–7 μmol/g 4‐O‐methylated sinapic acid were accumulated in MOMT transgenic lines. Both MOMTs in vitro displayed discernible substrate promiscuity towards a range of phenolics in addition to the dominant substrate monolignols, which partially explains their broad effects on grass phenolic biosynthesis. The cell wall structural and compositional changes resulted in up to 30% increase in saccharification yield of the de‐starched rice straw biomass after diluted acid‐pretreatment. These results demonstrate an effective strategy to tailor complex grass cell walls to generate improved cellulosic feedstocks for the fermentable sugar‐based production of biofuel and bio‐chemicals. [ABSTRACT FROM AUTHOR]