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Lignin is the renewable source of aromatics in nature, and the conversion of lignin into vanillin is very attractive. However, the vanillin yield is closely related to the resource of lignin and its isolation process, and relatively low yield of vanillin is always obtained from lignin. In order to improve the vanillin yield from lignin, in this work, the relationship between lignin linkages and vanillin yield was explored. Five lignins (kraft lignin, alkali lignin, lignosulfonate, and two enzymatic lignins) and various lignin model compounds (monomers, dimers, and polymers) were characterized by NMR spectroscopy and oxidized to prepare vanillin. Results indicated that the interunit linkages of the lignin had a significant influence on the vanillin yield. The more β- O -4 linkages in lignin, the higher yield of corresponding aldehydes was obtained. It is believed that the vanillin yield can be significantly improved by using lignins with high content of β- O -4 linkages. [ABSTRACT FROM AUTHOR]

Lignocellulosic materials are among the most promising alternative energy resources that can be utilized to produce cellulosic ethanol. However, the physical and chemical structure of lignocellulosic materials forms strong native recalcitrance and results in relatively low yield of ethanol from raw lignocellulosic materials. An appropriate pretreatment method is required to overcome this recalcitrance. For decades various pretreatment processes have been developed to improve the digestibility of lignocellulosic biomass. Each pretreatment process has a different specificity on altering the physical and chemical structure of lignocellulosic materials. In this paper, the chemical structure of lignocellulosic biomass and factors likely affect the digestibility of lignocellulosic materials are discussed, and then an overview about the most important pretreatment processes available are provided. In particular, the combined pretreatment strategies are reviewed for improving the enzymatic hydrolysis of lignocellulose and realizing the comprehensive utilization of lignocellulosic materials. [ABSTRACT FROM AUTHOR]

Abstract: Wood meal was dissolved under identical conditions in the ionic liquid 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) and homogeneously esterified with butyryl chloride and lauroyl chloride in the presence of triethylamine as a neutralizer. The effect of the molar ratio of reagent to the hydroxyl groups in wood on the properties of the esterified wood and the possible mechanism of the homogeneous esterification of wood in this reaction medium were studied. Furthermore, the physicochemical properties of the esterified wood were characterized by FTIR, solid-state CP/MAS 13C NMR, TGA/DTG and SEM. The results confirmed that the homogeneous modifications were successfully processed and highly substituted wood esters could be obtained by reacting the dissolved wood in this homogeneous system. [Copyright &y& Elsevier]

• A lignin-based cation exchange resin (LBR) was easily prepared in one-pot. • The phenolated and the sulfonated structures of lignin were confirmed by HSQC. • The LBR showed comparable ion-exchange capacity to the commercial phenol type resin. Lignin is a renewable source of aromatics, and the conversion of lignin to chemicals, fuels and materials is very attractive. Herein, a novel lignin-based cation exchange resin (LBR) was easily synthesized through an economical one-pot method. Results demonstrated that the sulfonic acid groups were successfully introduced into the skeleton of the resins, and the S contents and swelling capacity of the prepared LBRs gradually increased with the increment of the sulfonation reagents dosage. A maximum ion-exchange capacity of 2.26 mmol/g was achieved for the LBR obtained at 120 °C for 4 h with a molar ratio of phenol to formaldehyde (P:F) of 1:5 (SSPL-0.50), which was comparable to the commercial phenol type cation exchange resin. Furthermore, the SSPL-0.50 exhibited a high adsorption capacity (167.2 mg/g) for Pb (II) removal. The LBR can be considered as a promising substitute for the petroleum-based ion exchange resin in the purification of wastewater. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Pre-hydrolysis liquor is a promising feedstock to produce carbon microspheres (CM). • CM prepared from the PHL reduces the pollution load of the PHL significantly. • Sulfuric acid and lignin can significantly improve the formation of CM. • The functionalized CM showed good adsorption capacities for Pb(II) ion and MB. Abstract Pre-hydrolysis liquor (PHL) from the kraft-based dissolving pulp process contains large amounts of hemicelluloses, which is usually treated as an effluent and further efforts have to be involved to eliminate the pollution disposal. However, the hemicelluloses-rich PHL is a promising candidate for the production of carbon microspheres via hydrothermal carbonization. The yield of the carbon microspheres directly derived from the hydrothermal carbonization of the hemicelluloses-rich PHL (22.1%) was almost twice than that from xylose (13.1%). Furthermore, sulfuric acid and the lignin in the PHL could significantly improve the yield and change the size of the carbon microspheres obtained from the PHL. Additionally, the activated carbon microspheres functionalized with acrylic acid showed improved adsorption capacities for Pb(II) ion (273.4 mg/g) and methylene blue (701.3 mg/g). The hydrothermal carbonization of the PHL not only utilizes the hemicelluloses in the PHL, but also reduces the pollution load of the PHL significantly. [ABSTRACT FROM AUTHOR]

In this study, different pretreatment methods, including lyophilization, hydrothermal pretreatment, and ultrasound combined with dilute alkali post-cooking, were investigated to enhance the efficiency of enzymatic saccharification and biohydrogen production of the wheat straw. All pretreatment methods could effectively remove lignin and hemicellulose while retaining cellulose, further enhancing the biomass accessibility for subsequently enzymatic saccharification and biohydrogen production. A reducing sugar concentration of 13.18 g/L was acquired when wheat straw was treated with ultrasound and dilute alkali cooking (R U). The sequential fermentative hydrogen yield of the substrate R U was 133.6 mL/g total solids (TS), which was 5.6-fold larger than that of the raw material (23.9 mL/g TS). The study confirmed that ultrasound combined with dilute alkali cooking was an effective method, which not only provided significant guideline for improving biohydrogen production but also presented helpful direction for the efficient pretreatment of other lignocellulosic biomass. • Several pretreatments were assessed and compared for deconstruction of wheat straw. • Pretreatment effectively destroyed the structure of wheat straw. • Ultrasound combined with dilute alkali cooking increased reducing sugar yields. • A maximum biohydrogen yield of 133.6 mL/g total solids was achieved. • Proper pretreatment enhanced the hydrogen production performance of wheat straw. [ABSTRACT FROM AUTHOR]

Hydrothermal conversion (HTC) is an important thermochemical process to upgrade low-cost biomass into valuable chemicals or fuels. As compared with non-catalytic HTC, catalytic HTC shows high energy efficiency on biomass upgradation. In this work, the catalytic performances of various transition metal sulfates (Mn 2+ , Fe 2+ , Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , and Zn 2+ ) in the HTCs of xylose, glucose, and cellulose under different conditions were explored. Among these catalysts, Zn 2+ and Ni 2+ showed obvious effects on the conversions of xylose, glucose, and cellulose into lactic acid, while Cu 2+ and Fe 3+ , which could significantly accelerate the hydrolysis of cellulose into glucose at 200 °C, displayed high efficiency on converting glucose and cellulose into levulinic acid and formic acid at high temperature. Additionally, significant positive correlative relationships among xylose, glucose, and cellulose degradations were observed. This study is helpful for screening appropriate catalysts for biomass upgradation through catalytic HTC of monosaccharide. [ABSTRACT FROM AUTHOR]

The synergistic effects of graphene additive and surface micro-texturing on the friction and wear properties of rolling bearings are still a research gap. To this end, the tribological behavior of dimples textured thrust roller bearings (81107TN) are investigated under starved lubrication. The lubricants contained different mass fractions (0.06 %, 0.10 % and 0.14 %) of graphene. The evenly distributed dimples (diameter: 60 µm or 250 µm; depth: 1 µm or 8 µm) were manufactured only on the raceways of the shaft washers. By comparing the coefficients of friction (COF), wear losses and worn surfaces, the influence of various dimples dimensions and mass fractions of graphene on the tribological behavior of rolling bearings is discussed. The results show that appropriate dimple parameters and a suitable mass fraction of graphene can synergistically have a positive effect on the tribological properties of bearings. In this work, the textured group, with a dimple-diameter of 60 µm and a dimple-depth of 1 µm, can provide the best comprehensive friction-reducing and wear-reducing performance for the mass fraction of graphene with 0.10 wt%. Compared to the smooth bearings lubricated with base oil, its mean COF is reduced by 31 % and its wear loss by 35 %. This work can be a valuable reference for the improvement of rolling bearings and lubricants. [ABSTRACT FROM AUTHOR]

The present chemical converted graphene sheets are mostly dependent on the exfoliation of graphite with strong oxidants, which suffer from heavy burden of environmental pollution. Here, we report a simple, green and scalable method to synthesize graphene sheets by one-pot activation-synthesis method derived from black liquor, a biomass waste resource in pulping industry. The pulping black liquor consisting of alkali lignin as main components with phenyl skeletons and condensed aromatic segments was successively transferred from heterogeneous chemical states into micron-sized graphene sheets. The proposed conversion mechanism mainly consists of aromatic rebonding, refusion and deoxygenation reaction, in which alkaline species acting as situ-activation agent. The graphene sheets obtained from pulping black liquor (BL-G) show typical hexagonal honeycomb lattice in thickness of 1–3 atomic carbon layers with controllable lateral size ranging from 0.36 to 2.5 μm. After spin-coating single- or few-layer of BL-G sheets onto flexible substrate, it could produce transparent and conductive thin films (TCFs) with sheet resistance as low as 2.1 kΩ sq−1 and 85% transmittance for 550 nm light, suggesting its great potentials using as flexible electrode materials. This green synthesis route may pave a bright way in large-scale production of chemically converted graphene sheets. Image 1 [ABSTRACT FROM AUTHOR]

Forest wood biomass can be a sustainable and cost-effective feedstock for the biorefinery industries, but the rigid and compact structure of plant cell is a major barrier for production of clean energy and biochemical. In this case, the MIBK/H 2 O pretreatment with biphasic system was applied to treat Eucalyptus and then systematically evaluated pretreatment conditions (e.g., MIBK/H 2 O ratio, reaction temperature and time, NaCl concentration, and HCl dosage) on the effect of furfural yield. The resulting solid fraction obtained from the optimum pretreatment condition for furfural yield was to produce fermentable glucose by enzymatic hydrolysis. Study on enzymatic hydrolysis of the raw material and resulting solid fraction obtained by single aqueous system was also contrastively investigated. The furfural yield was 65.9% and the recovery of residue was 46.9% under an optimal reaction condition (V MIBK :V H2O  = 5:5, 150 °C, 60 min, 0.3 M HCl). Meanwhile, the yield of glucose of cellulose was improved after the pretreatments with different systems and a maximum value was up to 60.2% by the MIBK/H 2 O pretreatment. The effective fermentable glucose production was mainly affected by the significant removal of hemicelluloses, change of CrI, and destruction of surface morphology of Eucalyptus . The MIBK/H 2 O pretreatment can be considered as a potential approach for efficient conversion of Eucalyptus to clean energy and biochemicals. [ABSTRACT FROM AUTHOR]

Highlights: [•] Significant elemental difference was not found among biochars from different samples. [•] Carbonyl compounds were the major volatiles of polysaccharide pyrolysis. [•] Aromatic compounds were the major volatiles of lignin pyrolysis. [•] Except lignin, lignocellulosic material pyrolysis was mainly occurred at 200–400°C. [ABSTRACT FROM AUTHOR]