Search

Nanocellulose is a promising material but its isolation generally requires unrecyclable hazardous chemicals and high energy consumption and its overall yield is low due to the use of high purity cellulose as precursor. In order to overcome these shortcomings, in this study, thermomechanical pulp (TMP) was investigated as a precursor for isolating lignin containing nanocellulose (LNC) using an environmentally friendly acidic deep eutectic solvent (DES) pre-treatment. Flat "ribbon" like LNCs (around 7.1 nm wide, 3.7 nm thick) with uniformly distributed lignin nanoparticles of 20-50 nm in diameter were successfully obtained at 57 % yield under optimum pre-treatment conditions (90 °C, 6 h, 1:1 oxalic acid dihydrate to choline chloride ratio). The LNCs exhibit cellulose Iβ structure, high lignin content (32.6 %), and high thermal stability (T max of 358 °C). In general, green acidic DES pre-treatment has shown high efficiency in converting high lignin content biomass into value-added LNC, which benefits both lignocellulose utilization and environmental protection., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

While the cashew culture is focused on processing and commercialization of cashew nuts, the pseudofruit (cashew apples) - highly perishable and of limited acceptance - are mostly wasted. The cashew tree pruning fiber (CTPF) is another interesting cashew byproduct. In this study, films have been made from bacterial cellulose produced from cashew apple juice, and added with lignin (0-15 wt%) and cellulose nanocrystals (0-8 wt%), both from CTPF, which enhanced tensile properties and decreased water vapor permeability of the films. Moreover, lignin, although imparting brown color and opacity to the films, was effective to provide the films with UV-absorbing and antioxidant properties, making the films interesting for packaging of food products susceptible to lipid oxidation. The films did not exhibit antimicrobial activity against bacteria or yeasts., Competing Interests: Declaration of competing interest The authors have no conflicts of interest to declare., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A compounded medium of supercritical CO 2 , ethanol, and water (SEW) was used to extract lignin from eucalyptus fiber and the mechanism of the extraction was studied. Compared with the extraction method based on high-temperature ethanol (HTE), the lignin yield of the SEW method was 49.7% higher with higher average molecular weight. Physical and chemical synergies occurred during the extraction process. SEW compound medium penetrated eucalyptus fiber cell walls because of strong permeability, while the fast discharge of the compounded medium facilitated efficient lignin dissociation and removal. Carbonic acid formed from CO 2 and water under high temperature and pressure can provide an acidic environment to effectively degrade hemicellulose. Formaldehyde formed from CO 2 and ethanol in the process also prevented condensation of the extracted lignin fragments. The obtained lignin had high content of β-O-4 linkages and syringyl units., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Granulated cork was submitted to subcritical water extraction/hydrolysis in a semi-continuous reactor at temperatures in the range of 120-200 °C and with a constant pressure of 100 bar. The influence of temperature on the composition of the cork extracts obtained was assessed-namely, their content of carbohydrates and phenolics. The extraction yield increased with the temperature, and this was associated with the decrease in the dielectric constant of water and the increase in its ionic product. Extracts composed of up to 36% phenolics were obtained at temperatures of up to 120 °C, with an antioxidant activity only two times lower than that of pure gallic acid, but in low amounts. Assays at higher temperatures generated extracts richer in carbohydrates and with a phenolics content of ca. 20 wt.% in comparatively far higher amounts. Neither the amount of suberin nor its structure were affected by the subcritical water treatment.

The effects of sulfated organosolv lignins derived from fir (Abies sibirica) and larch (Larix sibirica) (SLf and SLl; 4-3-7.5% sulfur, median-weight molecular mass 2960-4888 Da), on human blood/plasma clotting, platelet aggregation, and erythrocyte hemolysis were studied in vitro. Antithrombin activities of the samples were below 2 U/mg. Specimens of SLf (sulfur content 6.5, 6.6, and 7.5%, molecular weights 3503, 3487, and 3580 Da, respectively) and SLl (4.3 and 6.3%, 2960 and 3497 Da) in a concentration of 0.01 mg/ml did not prolong the blood clotting time, did not provoke human platelet aggregation, did not destroy erythrocyte membranes, and could be used for construction of drug delivery systems. The SLf sample (6.5%, sulfur, 3503 Da) in concentrations from 0.09 to 1.82 mg/ml did not stimulate platelet aggregation, reduced ADP-induced platelet aggregation, and 2-fold prolonged the blood/plasma clotting time 2-fold in comparison with control and could be used for creation of biomaterial with clot-resistant surface.

Previous studies showed that aromatic compounds such as lignin, phenols, and furans were main inhibitors of cellulase hydrolysis in recycled alkali black liquor (RBL), which should be removed to improve alkali utilization. In this study, three polymeric resins, XAD-4, XAD-16N, and XAD-7HP, were evaluated for their abilities to remove lignin from alkali black liquor recycled at the third time. Adsorption conditions of adsorbent dose and equilibrium time, isotherms, and kinetics were investigated. Of three tested adsorbents, XAD-16N was the most efficient, which can remove 89.84% of lignin after adsorption at an adsorbent-to-solution ratio of 1:4 for 2.5 h. Pseudo-second-order model was efficient to represent XAD-16N and XAD-7HP adsorption kinetics. Adsorption behavior of XAD-4 on RBL was fitted better to Langmuir model, while XAD-16N and XAD-7HP adsorption were more consistent with Freundlich model. The cellulase hydrolysis rate of corn straw treated with RBL after XAD-16N adsorption combined with ozone was 86.89%, which was only 0.89% lower than that of sodium hydroxide combined with ozone treatment. Structure characterization proved that the damage of XAD-16N adsorbed RBL to corn straw was similar to that of sodium hydroxide. It indicated that adsorption was effective in inhibitor removal from RBL to improve alkali utilization.

Lignocellulosic materials are promising alternatives to non-renewable fossil sources when producing aromatic compounds. Lignins from Populus salicaceae . Pinus radiata and Pinus pinaster from industrial wastes and biorefinery effluents were isolated and characterized. Lignin was depolymerized using homogenous (NaOH) and heterogeneous (Ni-, Cu- or Ni-Cu-hydrotalcites) base catalysis and catalytic hydrogenolysis using Ru/C. When homogeneous base catalyzed depolymerization (BCD) and Ru/C hydrogenolysis were combined on poplar lignin, the aromatics amount was ca. 11 wt.%. Monomer distributions changed depending on the feedstock and the reaction conditions. Aqueous NaOH produced cleavage of the alkyl side chain that was preserved when using modified hydrotalcite catalysts or Ru/C-catalyzed hydrogenolysis in ethanol. Depolymerization using hydrotalcite catalysts in ethanol produced monomers bearing carbonyl groups on the alkyl side chain. The analysis of the reaction mixtures was done by size exclusion chromatography (SEC) and diffusion ordered nuclear magnetic resonance spectroscopy (DOSY NMR). 31 P NMR and heteronuclear single quantum coherence spectroscopy (HSQC) were also used in this study. The content in poly-(hydroxy)-aromatic ethers in the reaction mixtures decreased upon thermal treatments in ethanol. It was concluded that thermo-solvolysis is key in lignin depolymerization, and that the synergistic effect of Ni and Cu provided monomers with oxidized alkyl side chains.

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

VS 2 spheres and VS 2 sheets with doped compositions (Mo, Ag and graphite) were successfully prepared by one-step hydrothermal method and characterized by different techniques including X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N 2 adsorption isotherms. Catalysts were applied for the depolymerization of alkali lignin. VS 2 spheres exhibited lower yield of degraded lignin and bio-oil than those with VS 2 sheets and VS 2 flowers heated to 250 °C and held for 1.5 h with 2.0 MPa H 2 . The catalytic depolymerization performance was markedly affected by the dopant in the VS 2 sheets, with the highest degraded lignin yield of 81.22%, achieved over 5 wt% Ag-VS 2 at 290 °C under 2.0 MPa H 2 for 1.5 h, yielding 61.23% bio-oil. The VS 2 -based catalysts show excellent selectivity in the interruption of the lignin structure and target production of bio-oil. The bio-oil showed that the relevant contents of a phenolic-type compound changes significantly according to the dopant in the VS 2 catalyst., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Fractionation of lignocellulose into its three main components, lignin, hemicelluloses, and cellulose, is a common approach in modern biorefinery concepts. Whereas the valorization of hemicelluloses and cellulose sugars has been widely discussed in literature, lignin utilization is still challenging. Due to its high heterogeneity and complexity, as well as impurities from pulping, it is a challenging feedstock. However, being the most abundant source of renewable aromatics, it remains a promising resource. This work describes a fractionation procedure that aims at stepwise precipitating beech wood ( Fagus sp. ) lignin obtained with OrganoCat technology from a 2-methyltetrahydrofuran solution, using n -hexane and n -pentane as antisolvents. By consecutive antisolvent precipitation and filtration, lignin is fractionated and then characterized to elucidate the structure of the different fractions. This way, more defined and purified lignin fractions can be obtained. Narrowing down the complexity of lignin and separately valorizing the fractions might further increase the economic viability of biorefineries.

Horticultural plant residues (tomato, pepper, and eggplant) were identified as new sources for lignocellulose nanofibers (LCNF). Cellulosic pulp was obtained from the different plant residues using an environmentally friendly process, energy-sustainable, simple, and with low-chemical reagent consumption. The chemical composition of the obtained pulps was analyzed in order to study its influence in the nanofibrillation process. Cellulosic fibers were subjected to two different pretreatments, mechanical and TEMPO(2,2,6,6-Tetramethyl-piperidin-1-oxyl)-mediated oxidation, followed by high-pressure homogenization to produce different lignocellulose nanofibers. Then, LCNF were deeply characterized in terms of nanofibrillation yield, cationic demand, carboxyl content, morphology, crystallinity, and thermal stability. The suitability of each raw material to produce lignocellulose nanofibers was analyzed from the point of view of each pretreatment. TEMPO-mediated oxidation was identified as a more effective pretreatment to produce LCNF, however, it produces a decrease in the thermal stability of the LCNF. The different LCNF were added as reinforcing agent on recycled paperboard and compared with the improving produced by the industrial mechanical beating. The analysis of the papersheets' mechanical properties shows that the addition of LCNF as a reinforcing agent in the paperboard recycling process is a viable alternative to mechanical beating, achieving greater reinforcing effect and increasing the products' life cycles.

In this work, an effective sequential organic solvent extraction of kraft and organosolv lignins was carried out to separate lignin into more homogeneous fractions with specific properties. The selected solvents were ethyl acetate, ethanol, methanol, and acetone in that order. Fractions were analysed in terms of their yield, molecular weight, S/G ratio, and phenolic hydroxyl groups content. The incorporation of lignin fractions into the chitosan was aimed to increase the UV absorbance and the mechanical resistance of the chitosan films, which would provide good properties for applications in the packaging field. Films were analysed in terms of UV-vis absorption spectra, tensile strength, as well as colour changes. Results showed a significant increase in the absorbance of UV-A and UV-B with the addition of lignin fractions, mechanical properties showed an increase in the ultimate tensile strength in case of kraft fractions, while organosolv fractions do not affect tensile strength significantly., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Ethnopharmacological Relevance: Litsea cubeba (Lour.) Pers. has been traditionally used as a folk prescription for treating rheumatic diseases in China., Aim of the Study: This study aimed to investigate the effects and underlying mechanism of LCA, a new type of dibenzyl butane lignin compound extracted from L. cubeba, on macrophage colony stimulating factor (M-CSF) plus receptor activator of NF-κB ligand (RANKL)-induced osteoclast differentiation in mouse-derived bone marrow macrophages (BMMs)., Material and Methods: TRAP staining, TRAP enzyme activity assay and actin ring staining were applied to identify the effects of LCA on osteoclast differentiation. Protein expression of NFATc1, c-Fos and MMP-9, and phosphorylation of p65, Akt, JNK, ERK and p38 in RANKL-induced osteoclasts was determined using western blotting to investigate the underlying mechanism., Results: LCA significantly suppressed RANKL-induced osteoclast differentiation by inhibiting TRAP activity, decreasing the number of TRAP + multinuclear osteoclasts and reducing the formation of F-actin ring without obvious cytotoxicity in BMMs. Moreover, LCA treatment strongly reduced protein expression of NFATc1, c-Fos and MMP-9, and attenuated the phosphorylation of p65, Akt, JNK, ERK and p38 in RANKL-stimulated BMMs., Conclusions: LCA ameliorated RANKL-induced osteoclast differentiation via inhibition of Akt and MAPK signalings in BMMs, and may serve as a potential pro-drug for bone destruction prevention., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this work, lignin fractionation is proposed as an effective approach to reduce the heterogeneity of lignin and improve the adsorption and recycle performances of lignin as a cationic dye adsorbent. By stepwise dissolution of enzymatic hydrolysis lignin in 95% and 80% ethanol solutions, three lignin subdivisions (95% ethanol-soluble subdivision, 80% ethanol-soluble subdivision, and 80% ethanol-insoluble subdivision) were obtained. The three lignin subdivisions were characterized by gel permeation chromatography (GPC), FTIR, 2D-NMR and scanning electron microscopy (SEM), and their adsorption capacities for methylene blue were compared. The results showed that the 80% ethanol-insoluble subdivision exhibited the highest adsorption capacity and its value (396.85 mg/g) was over 0.4 times higher than that of the unfractionated lignin (281.54 mg/g). The increased adsorption capacity was caused by the enhancement of both specific surface area and negative Zeta potential. The maximum monolayer adsorption capacity of 80% ethanol-insoluble subdivision by adsorption kinetics and isotherm studies was found to be 431.1 mg/g, which was much higher than most of reported lignin-based adsorbents. Moreover, the 80% ethanol-insoluble subdivision had much higher regeneration yield (over 90% after 5 recycles) compared with the other two subdivisions. Consequently, the proposed fractionation method is proved to be a novel and efficient non-chemical modification approach that significantly improves adsorption capacity and recyclability of lignin.

A facile eco-friendly approach for acetampirid pesticide removal is presented. The method is based on the use of micro- and mesoporous activated carbon (TPAC) as a natural adsorbent. TPAC was synthesized via chemical treatment of tangerine peels with phosphoric acid. The prepared activated carbon was characterized before and after the adsorption process using Fourier- transform infrared (FTIR), X-ray diffraction (XRD), particle size and surface area. The effects of various parameters on the adsorption of acetampirid including adsorbent dose (0.02-0.2 g), pH 2-8, initial adsorbate concentration (10-100 mg/L), contact time (10-300 min) and temperature (25-50 °C) were studied. Batch adsorption features were evaluated using Langmuir and Freundlich isotherms. The adsorption process followed the Langmuir isotherm model with a maximum adsorption capacity of 35.7 mg/g and an equilibration time within 240 min. The adsorption kinetics of acetamiprid was fitted to the pseudo-second-order kinetics model. From the thermodynamics perspective, the adsorption was found to be exothermic and spontaneous in nature. TPAC was successfully regenerated and reused for three consecutive cycles. The results of the presented study show that TPAC may be used as an effective eco-friendly, low cost and highly efficient adsorbent for the removal of acetamiprid pesticides from aqueous solutions.

In this work, we investigated the antioxidant and immunomodulatory activities of a lignin isolated from Conocarpus erectus leaves. The lignin was characterized by FTIR, 1 H NMR, 13 C NMR and gel permeation chromatography analysis as well as ultraviolet/visible absorption spectra. The lignin was evaluated for total antioxidant activity (TAA), DPPH and ABTS + scavenging abilities, and by a lipid peroxidation inhibition assay. Immunomodulatory activity of the lignin (10 μg/mL) on human peripheral blood mononuclear cells (PBMCs) was determined. The C. erectus lignin was found to be of the guaiacyl-syringyl-p-hydroxyphenyl (G-S-H) type, with an average molecular weight of 2709 Da (polydispersity index: 2.1). It showed low TAA (17.92%) and moderate antioxidant activity against DPPH and ABTS + (IC 50 : 231.16 and 356.03 μg/mL, respectively). It also inhibited lipid peroxidation by 42.14%. The lignin promoted an increase in mitochondrial ROS levels as well as cytosolic Ca 2+ in PBMCs. In addition, it promoted the differentiation and activation of CD8 + T lymphocytes, differentiation of CD14 + monocytes, and stimulated the release of nitric oxide and cytokines, mainly those linked to a Th1 response. The results showed that the C. erectus lignin may be used in future studies in which the modulation of the immune response is a key factor., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Lignin based materials and chemicals with outstanding sustainability have drawn increasingly attentions. However, the dark color of lignin limits the utilization in color-depended fields. In this work, the factors that influence the color of lignin were investigated and mechanisms were illustrated by GPC, NBO, 2D HSQC, XPS, SEM, and visible light spectrum. It is found that the condensed structures were mainly separated at higher pH due to its high molecular weight and low solubility. The condensation contributes to the conjugation and unsaturation, which resulted in the dark-color of the lignin precipitated at high pH value. The oxidation is not crucial for the color darkening of lignin in drying, it is the micro aggregation that dominantly determined the color degree. The concentration of chromophore was decreased owing to the decrease of bulk density (caused by the alleviation of aggregation), which endowed lignin with the bright seeing macroscopically. Notably, the selection of light-colored lignin needs to be individually considered regarding different use, since the dominating factors that influence the color at solid or solution are totally different. In summary, this work offers guidance for acquiring light-colored lignin and helps people select the light-colored lignin properly regarding utilizations., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Biomass derived fillers have been developed as sustainable substitution of carbon black (CB) used in rubber industry to reduce the dependence on fossil fuels. Lignin is the abundant component of biomass, but has poor reinforcing performance due to its huge particle size. In this work, we prepared a lignin/silica (LS) hybrid material from rice husks via a facile self-assembly method. The formation of LS cut lignin macromolecules into fragments and resulted in a small average particle size of 320 nm. When LS was filled into the natural rubber to substitute 10 phr CB, both filler-filler interaction and filler-rubber interaction were enhanced compared with the single use of CB. In consequence, the obtained 10LS/40CB/NR vulcanizates showed overall improvement in tensile strength, tear strength and abrasion resistance compared with the 50CB/NR vulcanizates. For the sustainable development of rubber industry, the natural LS hybrid material with low production cost is a promising reinforcing filler for the partial replacement of CB., Competing Interests: Declaration of competing interest The authors declared no conflicts of interest., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The aflatoxin B1 (AFB1) adsorption properties of several lignins isolated by the Pepper's method from grassy plants: Helianthus tuberosus (LS-1), Atriplex patula (LS-2), Rhododendron tomentosum (LS-3), Althaea officinalis (LS-4), Lavatera (LS-5), and from wood of spruce Pícea (LS-6) were studied. The adsorption was conducted in vitro in the modeled conditions of the gastrointestinal tract. The correlations between the values of adsorption-desorption and the parameters of surface-porous structure and chemical structure of the lignins were established. The relationships between the adsorption capacity and properties of the lignins led us to the conclusion that chemisorption play the most important role in the strong adsorption of aflatoxin B1. The contribution of the surface physical properties to the process of adsorption of aflotoxin B1 was not significant. It was shown that the sample of lignin isolated from stems of Althaea officinalis, was characterized by the highest value of strong adsorption of aflatoxin B1., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2019 Elsevier B.V. All rights reserved.)

It is important to make full utilization of industrial biomass residues. Pulp was prepared from licorice residues by soda-anthraquinone pulping followed by peroxyacetic acid bleaching. Cellulose nanofibril was obtained by enzymatic pretreatment followed by homogenization of the pulp (ETCNF). The effects of enzymatic pretreatment on ETCNF were investigated. Chitosan nanofibril (CHN) and lignin nanoparticles (LNPs) were prepared and used for ETCNF composites, respectively. The results showed that ETCNF exhibited clear nanofibrillar structure and a highly relative colloidal stability, and a much higher crystallinity index and thermal stability compared to TEMPO-medicated oxidized one; the cellulose composite films incorporated with CHN or LNPs exhibited good thermal stability and hydrophobicity. Compared with ETCNF film, ETCNF@LNPs-5.0% film showed higher UV-blocking ability and thermal stability, but reduced light transmittance, while ETCNF@CHN-5.0% film showed improved mechanical properties and similar light transmittance. This study would expend licorice residues as potential materials for CNF and its applications., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The use of three organic acids such as acetic, lactic and citric acid has been investigated as green precipitation agents for kraft lignin isolation from the industrial hardwood black liquor. Chemical composition, molecular structure characteristics in addition to thermal and antioxidant properties were evaluated and compared to kraft lignin precipitated with sulfuric acid. A clear influence of the organic acids was observed in the chemical composition and molecular properties. Organic acids generated lignins with high purity and low ash and carbohydrate contents. FT-IR and Py-GC-MS analyses revealed the ability of organic acids to produce lignins with greater content of methoxylated structures and carbonyl groups than sulfuric acid. Moreover, all evaluated kraft lignins exhibited a suitable radical scavenging activity, and higher than found for commercial antioxidant used as control. TG analysis showed that the employment of organic acids with higher ionic strength lead less thermally stable kraft lignin. In addition, the proximate analysis confirmed the high potential of kraft lignins as an energy source (21-24 MJ/Kg)., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Food and agro-processing industries generate a huge quantity of solid waste which is rich in bio-macromolecules like lignin. The extraction of lignin biomolecules can help in the efficient management of such waste along with the generation of wealth from the waste. The groundnut shells are one of the lignin-rich wastes which could be utilized for the extraction of lignin biomolecules. The present work investigates an innovative approach involving the application of extracted lignin biomolecules for the value-addition to wool fabrics. Metallic mordants were utilized to get a wash-fast attachment of lignin with wool. The change in the appearance of wool fabrics was analyzed using reflectance spectroscopy. The finished fabrics were further evaluated for the functional properties like antioxidant activity, antibacterial activity and UV protection. The functionalized wool fabrics displayed a variety of shades with different combinations of groundnut shell lignin (GSL) and mordant. Thermal stability of treated wool fabrics was analyzed by thermogravimetric analysis. The functionalized wool fabrics showed significant antioxidant activity (69.5-84.5%), antibacterial activity (79.7-86.3%) and UV protection (UPF ratings of 50 + )., (Copyright © 2019 Elsevier B.V. All rights reserved.)

This work tailored a promising two-step pretreatment, i.e., liquid hot water extraction followed by mild acidic deep eutectic solvents pretreatment for clean lignocellulose fractionation while enhancing cellulose reactivity for its subsequent utilization. The abilities of three acidic deep eutectic solvents (formic acid-, acetic acid- and lactic acid-choline chloride) to selectively extract poplar wood lignin and enhance cellulose reactivity were comparatively assessed. Results showed that rather high lignin selectivity of 6.3-7.9 was obtained while the available area and porosity of the resulting cellulose were significantly increased. The resulting cellulose pulps exhibited comparable chemical reactivity to commercial bleached Kraft pulp when cellulose acetate was selected as testing cellulose derivative for demonstrating purpose, showing their great promise for high-value use. It was proposed that the unique ionic properties of these acidic deep eutectic solvents were responsible for their selective lignin removal and cellulose swelling/deconstruction to enhance cellulose chemical reactivity., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: The lemongrass (LG) leaves could be a useful source of cellulose after its oil extraction, which is still either dumped or burned, not considered as a cost-effective approach. The synthesis of cellulose nanofibers (CNF) from LG waste has emerged as a beneficial alternative in the value-added applications. The non-toxicity, biodegradability, and biocompatibility of CNF have raised the interest in its manufacturing., Method: In the present study, we have isolated and characterized CNFs using enzymatic hydrolysis. We also explored the cytotoxic properties of the final material. The obtained products were characterized using dynamic light scattering (DLS), fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), and thermogravimetric/differential thermal gravimetric analysis (TG/DTG). The cytotoxicity of CNF was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay against three different cancer cell lines NCIH460, PA1, and L132 cells., Results: The FT-IR results showed that the resulting sample was of cellulose species, and CNF was found free from the non-cellulosic components like lignin and hemicellulose. The SEM micrographs of the cellulose showed a bundle like structure. The TEM micrographs of CNF showed diverse long fibers structure with 105.7 nm particle size analysed using DLS. The TGA analysis revealed that the thermal stability was slightly lower, compared to cellulose. Additionally, CNF did not show the cytotoxic effect at the tested concentrations (~10-1000 μg/ml) in any of the cell lines., Conclusion: Overall, the results concluded that LG waste-derived CNF is a potential sustainable material and could be employed as a favourable reinforcing agent or nanocarriers in diverse areas, mainly in food and drug delivery sectors. Graphical abstract Systematic representation of the synthesis of the cellulose nanofibers: The lignocellulosic waste of lemongrass (after oil extraction) was pretreated for the isolation of raw cellulose, followed by enzyme hydrolysis for the synthesis of pure cellulose nanofibers.

High-strength and water resistant lignocelluloses based composites (LC) were fabricated using branched polyethylenimine (PEI) as the main bonding agent combined with glutaraldehyde cross-linking reaction and grinding pre-treatment. Physical and mechanical properties of different composites prepared were measured and investigated. It is evident that PEI was efficient in endowing LC with high strength and excellent water resistance. The obtained physical and mechanical properties of LC were complied with the requirement of the Chinese national standard for medium-density fiberboard (MDF). Most notably, the glutaraldehyde cross-linking and grinding pre-treatment could further improve these properties. When 5% PEI and 2.5% glutaraldehyde were incorporated, together with 2-hour grinding treatment, the LC prepared exhibited the optimum modulus of rupture (MOR) 58.1 MPa, modulus of elasticity (MOE) 5077 MPa, internal bonding strength (IB) 2.14 MPa, and thickness swell (TS) 30.2%. The excellent properties obtained could be attributed to the cross-linking effect and Schiff's base addition reaction among lignocelluloses, PEI and glutaraldehyde, which were confirmed by the Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analysis. The high-strength LC prepared in this study is expected to be used as load-bearing material in structural application., (Copyright © 2019. Published by Elsevier B.V.)

The present study was aimed to evaluate the Methyltrioctylammonium Chloride (IL) and Sodium hydroxide effect on sugarcane bagasse (SB) structure and its subsequent utilization to produce cellulase from a thermophilic bacterium Bacillus aestuarii UE25. The strain was isolated from a crocodile pond of Manghopir, Karachi. Ten different factors affecting IL pretreatment of SB and cellulase production by UE25 were evaluated by Plackett-Burman design and three significant factors were optimized by employing Box Behnken design. Under optimum conditions, the strain produced 118.4 IU mL -1 of EG and 75.01 IU mL -1 of BGL that corroborated well with the predicted values by the model. Scanning electron microscopy, gravimetric analysis, Fourier transform infrared spectroscopy and NMR of SB revealed removal of lignin, decrease in cellulose content and structural changes in the SB after pretreatment and fermentation. The data provide prospects of utilizing this IL in comparison to imidazolium based IL for pretreatment of biomass., (Copyright © 2019 Elsevier B.V. All rights reserved.)

This study demonstrated the effect of two-pot sequential pretreatment, comprising of ultrasound assisted deep eutectic solvent (DES) with the aim to investigate the effects of ultrasound amplitude and duration in enhancing delignification. Oil palm fronds (OPF) were ultrasonicated in a water medium, followed by a pretreatment using DES (choline chloride:urea). Fourier transform infra-red spectroscopy, X-ray diffraction, field emission scanning electron microscope, Brunauer-Emmet-Teller and solubilised lignin concentration were conducted to confirm the effectiveness of ultrasound assisted DES on the pretreatment of OPF. The recommended ultrasound conditions were determined to be 70% amplitude and duration of 30 min, where the sequential DES pretreatment was able to reduce lignin content of OPF to 14.01%, while improving xylose recovery by 58%., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Understanding the distribution and structural features of lignin in heartwood, sapwood, and bark of terrestrial plants is important to optimize the industrial utilization of lignocellulose. In this work, the lignins in heartwood, sapwood, and bark of Eucalyptus urophylla × E. grandis were comparatively studied. Confocal Raman microscopy was used to probe the heterogeneity of lignin distribution in situ. The swollen residual enzyme lignin samples were isolated and systematically characterized to determine the structural differences. The results showed that the content and molecular weights of lignin gradually decreased in the order of heartwood, sapwood, and bark. The S/G ratios of heartwood lignin (3.45) and sapwood lignin (2.74) suggested the increase of deposited S-type lignin with the maturity of wood. The bark lignin exhibited a high frequency of β-O-4' linkages and showed a unique substructural pattern with the absence of spirodienone substructures and p-hydroxycinnamyl alcohol end-groups., (Copyright © 2018. Published by Elsevier B.V.)

Lignin was fractionated with several organic solvents and fractions were utilized for UV resistant lignin-PLA composites. First, soda lignin (SL) was sequentially fractionated into six fractions: ethyl acetate (F1), 2-butanone (F2), methanol (F3), acetone (F4), dioxane/water (F5), and an insoluble fraction (INS). Molecular weight of the fractions increased from F1 to F5 and phenolic hydroxyl contents decreased with increasing molecular weight of fractions. Five lignin fractions (SL, F1, F3, F5, and INS) were grafted with l-lactide to produce lignin-grafted poly-l-lactide (PLLA) copolymers. Conversion ratio of l-lactide to PLLA chains increased from 88.3% for F5-PLLA copolymer to 91.2% for F1-PLLA copolymer as the content of hydroxyl groups in the fraction increased, while the molecular weight of the copolymers showed the reverse tendency. Each copolymer was mixed with PLA 2002D, and mechanical and optical properties of the composites were investigated. Composites of F1, F3, and F5 showed a tensile strength around 65 MPa, which is similar to that of neat PLA. The elastic modulus increased from 2197.7 for F1 to 2503.4 MPa for F5. According to the investigation of UV-VIS transmittance of the composite films, composites of F3 and F5 showed better UV blocking ability than the other composites, and this UV blocking ability increased with increasing concentration of lignin copolymer., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In the present study, methanolysis of poplar biomass was conducted for the selective transformation of hemicellulose and lignin, which leads to methyl glycosides (mainly C5 glycosides) and lignin fragments in the liquefied products that can be separated according to their difference in hydrophilicity. The distribution of methyl glycosides and delignification was dependent on the presence of acid catalysts and reaction temperatures. The obtained lignin fraction was separated into solid lignin fragments and liquid lignin oil according to their molecular weight distribution. Subsequently, directional conversion of methyl C5 glycosides into methyl levulinate was performed with dimethoxymethane/methanol as the cosolvent. A yield of 12-30% of methyl levulinate yield (based on the methyl glycoside) was achieved under these conditions. The remaining cellulose-rich substrate showed enhanced susceptibility to enzymatic hydrolysis, resulting in a yield of glucose of above 70%. Overall, the described strategy shows practical implications for the effective valorization of biomass.

The açaí fruit depulping produces large amounts of long lignocellulosic fiber bundles that are disposed in the environment. Chemical pretreatments may improve açaí fibers favoring their usage in advanced materials. This work aimed to define optimal alkali reaction parameters to improve the properties of açaí fibers. Two NaOH concentrations (5 % and 10 %) and two reaction temperatures (80 °C and 100 °C) were tested. The raw and treated fibers were analyzed by scanning electron microscopy, Fourier transformed infrared spectroscopy, X-ray diffraction, and thermal analyses. All the alkali pretreatments separated fibers from the bundles, unblocked pit channels by removing silicon structures, exposed the inner lignin, partially removed non-cellulosic compounds, and raised the cellulose crystalline index. The highest temperature and NaOH content resulted in better cleaning and isolation of the fibers, while milder conditions better preserved the cellulose crystalline structure and thermal stability., (© 2019 Wiley-VHCA AG, Zurich, Switzerland.)

Kraft lignin is a polyphenolic compound generated as a by-product from the kraft pulping process in large quantities annually worldwide. In addition to its commercial availability, its structural features make it worth to be considered in the pharmaceutical area. The present study was carried out to evaluate in vitro antioxidant and cytotoxic properties of kraft lignin on mouse hepatoma MH-22A, melanoma B16 (tumor cells) and Chinese hamster ovary (CHO, non-cancerous) cells. Moreover, several analytical techniques were used in order to elucidate the chemical structure of isolated industrial lignins (FT-IR, GPC, Py-GC-MS, 2D HSQC NMR). Results revealed high phenolic content in their composition, high-condensed structure and high phenolic hydroxyls group content. DPPH and ABTS ⁎+ radical scavenging assays demonstrated their strong antioxidant activity, which was higher than found for commercial antioxidant (BHT). Kraft lignins act cytotoxically inducing apoptosis- and necrosis-like processes on both on tumor and normal cells. However, the results evidenced that MH-22A cells showed greater sensitive behavior than B16 and non-cancerous CHO cells, which were more tolerant of kraft lignin., (Copyright © 2019 Elsevier B.V. All rights reserved.)

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

The conversion of lignocellulosic biomass into biofuels and bio-products leads to oxygenated matrices having a wide range of polarities and molecular weights. A complete analytical characterization of these complex mixtures is necessary to improve conversion processes. In this study, an innovative centrifugal partition chromatography (CPC) protocol was developed to fractionate aqueous biomass samples with a MTBE-water solvent system, by mixing elution, displacement and extrusion modes in the same run. This new protocol was validated on model molecules and applied to the water soluble phase of a fast pyrolysis bio-oil. It demonstrated a promising separation with a relevant selectivity on the most significant chemical families of biomass samples: carbohydrates, furans, carboxylic acids and phenols. CPC fractions of the sample were collected and analyzed comprehensively by HPLC-UV/MS (with ESI negative and positive ionization modes). This CPC x LC approach allowed more accurate attributions on the 217 peaks detected. The use of different detection modes gave a complete view of the water soluble phase of a fast pyrolysis bio-oil through 2D maps. Molecular characterization was enhanced by independent information: CPC retention time, LC retention time, UV and MS spectra. Concomitance of these different chemical information is of precious help for unambiguous identification., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Over the recent years, the exploitation of antibacterial performance of lignin and its subsequent usage as bacteriostatic additives has gained increasing interests. However, due to the restriction from structural heterogeneity, the antibacterial activity of lignin is always modest and unstable (especially against Gram-negative bacteria). In this regard, we proposed a facile one-step ethanol fractionation process to decrease the heterogeneity of lignin and, therefore, improve its antibacterial activity. Two fractions (Fs and Fi, 95% ethanol soluble and insoluble fraction, respectively) were obtained from bamboo kraft lignin (BKL) and their antibacterial effectiveness was compared. The results showed that the antibacterial activity of Fs increased significantly compared to that of BKL. On the contrary, Fi barely exhibited inhibitory effect on the growth of two Gram-positive bacteria and even promoted the growth of two Gram-negative bacteria. The much lower phenolic-OH content in Fi was an important reason for the absence of antibacterial activity. Besides, the growth promotion of Gram-negative bacteria by Fi was possibly caused by the formation of insoluble carriers for bacteria growth due to the poor water-solubility of Fi. Accordingly, after the elimination of Fi, the one-step fractionation significantly enhanced the antibacterial activity of lignin against both Gram-positive and Gram-negative bacteria., (Copyright © 2019 Elsevier B.V. All rights reserved.)

An adsorption resin CX-6 was synthesized and used for acid soluble lignin (ASL) removal from sugarcane bagasse hydrolysate (SCBH). The adsorption conditions of pH value, amount of adsorbent, initial ASL concentration, and temperature on ASL adsorption were discussed. The results showed the adsorption capacity of ASL was negatively affected by increasing temperature, solution pH, and adsorbent dose, and was positively affected by increasing initial concentration. The maximum adsorption capacity of ASL was 135.3 mg/g at initial ASL concentration 6.46 g/L, adsorption temperature 298 K, and pH 1. Thermodynamic study demonstrated that the adsorption process was spontaneous and exothermic. Equilibrium and kinetics experiments were proved to fit the Freundlich isotherm model and pseudo-second-order model well, respectively. Fermentation experiment showed that the SCBH after combined overliming with resin adsorption as fermentation substrate for microbial lipid production by Trichosporon cutaneum and Trichosporon coremiiforme was as better as that of SCBH by combined overliming with active charcoal adsorption, and more efficient than that of SCBH only by overliming. Moreover, the regeneration experiment indicated that the CX-6 resin is easy to regenerate and its recirculated performance is stable. In conclusion, our results provide a promising adsorbent to detoxify lignocellulose hydrolysate for further fermentation.

As fossil fuel resources dwindle and new regulations for a cleaner and safer environment come on stream, there is growing interest in developing new sustainable feedstocks for future fuels, chemicals, polymers and fibers. Therefore materials research is ever more focused on the production of green or bio-based materials and their composites. Lignocellulosic biomass has become the feedstock of choice for these new materials as cellulose and lignin are the most abundant biopolymers on the planet. Lignin is a phenolic macromolecule, the principal biological source of aromatic structures, with a complex structure which varies depending on plant species and its isolation process. Despite its high carbon content and its potential as a raw material, lignin remains underutilised. Between 40 and 50 million tons of lignin are produced worldwide per year; while some is being used for low- and medium-value applications, most is currently treated as a non-commercialized by-product or as low value fuel to produce energy. However, with the emergence of biorefinery projects larger amounts of lignin with the potential for valorisation are being produced. Here, we summarise some of the latest developments in the field., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Steam-explosion lignin (SEL) was extracted with ethanol from steam-exploded hardwood (okoumé, Aucoumea klaineana Pierre) pretreated at various severities after neutral or acidic impregnation. The SELs were subjected to structural characterization by 2D HSQC NMR, 31 P NMR, and SEC and compared with milled-wood lignin (MWL). A strong decrease in the β- O-4 content is observed with increasing steam-explosion severity accompanied by a gradual increase in molecular mass. Cα-oxidized S units (S', Hibbert's ketones) were quantified by NMR and used as a marker of the hydrolytic mechanism; naphthol was used as a carbonium-ion scavenger. It has been observed that mixed reactions of hydrolysis and homolysis are involved, but the SEL is mainly cleaved homolytically, favoring recondensation through radical coupling even at low reaction severity. However, acidic preimpregnation of wood prior to steam explosion enhanced the carbonium-ion pathway.

Four different lignin samples were isolated during the processing of rice straw for ethanol production: one after mild alkaline pretreatment (deacetylation) of rice straw, and other three after simultaneous saccharification and fermentation (fermentation residues), under different process conditions. Then, a complete chemical characterization in terms of main components (lignin, carbohydrates, among others) and elemental composition was performed for all the samples. Additionally, the structural and morphological characteristics, calorific value, thermal stability, solubility in solvents and antioxidant potential were also determined. For comparison, a standard lignin (Kraft lignin) was also assayed. The results revealed that the process used for lignin isolation has an important influence in the final properties of the sample. In general, the fermentation residues contained non-hydrolyzed polysaccharides in their composition and lower lignin content when compared to the lignin solubilized in the alkaline liquor. Among several organic solvents and mixtures, acetone 80% (v/v) was the most efficient for lignin solubilisation. Interesting properties and characteristics were observed for all the lignin samples isolated from rice straw processing, which would allow their application in different industrial areas. Based on the properties, potential applications were suggested, which could be of value for integration in biorefineries., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Environmental considerations in recent times have led to increasing interest in naturally occurring lignocellulosic materials as they are abundant and biodegradable. Pearl Millet (PM) stalks are currently discarded in North India and add to agrowaste generation. In this study, raw stalk of PM was characterized for physicochemical properties such as composition, moisture content, water absorbency and thermal behaviour. Morphology and crystallinity were studied using scanning electron microscope and X-ray diffraction respectively. Pure cellulose, extracted from the stalk using an optimised process, was characterised similarly. XRD patterns indicate the presence of cellulose type I structure with crystallinity index of 32% for raw stalk and 55% for the purified material. Water absorbency was 10 g/g for raw and 13 g/g for extracted cellulose. Material was thermally stable up to 200 °C. These findings indicate that PM stalks may be used as an indigenous source of cellulose for the absorbent layer in hygiene products., (Copyright © 2019. Published by Elsevier Ltd.)

Glucuronoyl esterases (CE15 family) enable targeted cleavage of ester linkages in lignin-carbohydrate complexes (LCCs), particularly those linking lignin and glucuronoyl residues in xylan. A substantial challenge in characterization and kinetic analysis of CE15 enzymes has been the lack of proper substrates. Here, we present an assay using an insoluble LCC-rich lignin fraction from birch; lignin-rich pellet (LRP). The assay employs quantification of enzyme reaction products by LC-MS. The kinetics of four fungal CE15 enzymes, PsGE, CuGE, TtGE, and AfuGE originating from lignocellulose-degrading fungi Punctularia strigosozonata, Cerrena unicolor, Thielavia terrestris, and Armillaria fuscipes respectively were characterized and compared using this new assay. All four enzymes had activity on LRP and showed a clear preference for the insoluble substrate compared with smaller soluble LCC mimicking esters. End-product profiles were near identical for the four enzymes but differences in kinetic parameters were observed. TtGE possesses an alternative active site compared with the three other enzymes as it has the position of the catalytic glutamic acid occupied by a serine. TtGE performed poorly compared with the other enzymes. We speculate that glucuronoyl LCCs are not the preferred substrate of TtGE. Removal of an N-terminal CBM on CuGE affected the catalytic efficiently of the enzyme by reducing K cat by more than 30%. Reaction products were detected from all four CE15s on a similar substrate from spruce indicating a more generic GE activity not limited to the hardwood. The assay with natural substrate represents a novel tool to study the natural function and kinetics of CE15s.

Crude supercritical lignin (SCL) extracted from hardwood (Quercus mongolica) treated via supercritical water (SCW) oxidation was subjected to sequential fractionation with four organic solvents; five lignin fractions (F1-F4 and F IN ) were thus obtained. The molecular weight (MW) of the fractionated lignins gradually increased as fractionation proceeded. However, the content of methoxyl groups and phenolic hydroxyl groups tended to decrease with increasing molecular weight of the lignins. The functional groups of SCL and the fractionated lignins were very similar based on Fourier-transform infrared analysis. The syringyl/guaiacyl ratio (S/G ratio) of the fractionated lignins increased with an increase in the MW. The thermal stability decreased with decreasing MW of the fractionated lignins, and all fractions except for F1 had a maximum degradation temperature of around 360 °C. The glass transition temperature (T g ) of the fractions increased from 83 °C to 137 °C with increasing MW., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Two new coumarinolignoids, sapiumins D (1) and E (2), a new lignanoid, lariciresinol 9'-benzoate (3), together with six known coumarinolignoids (4-9) and eight known lignanoids (10-17), were isolated from the stems and leaves of Sapium discolor. The structures of the isolated compounds were elucidated by extensive spectroscopic methods, including NMR, MS, and single crystal X-ray diffraction experiments. Compounds 5, 10, 11, and 13 significantly inhibited nitric oxide production in lipopolysaccharide-induced BV-2 microglial cells, with IC 50 values in the range of 2.13-11.37 μM., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Opuntia fícus-indica and Opuntia cochenillifera are species of Cactaceae, found in the arid regions of the planet. They present water, cellulose, hemicellulose, pectins, extractives, ashes and lignins. Here we aimed to study the immunomodulatory action of lignins from these two species against mice splenocytes, since no study for this purpose has yet been reported. The antioxidant activities of these lignins were evaluated by the DPPH, ABTS, NO assays and total antioxidant activity. Cytotoxicity was evaluated through Annexin V-FITC and propidium iodide-PE probs and cell proliferation was determined by CFSE. Immunomodulation studies with Opuntia lignins obtained were performed through investigation of ROS levels, cytosolic calcium release, changes on mitochondrial membrane potential, cytokine production and NO release. Results showed that Opuntia cochenillifera lignin presented more phenolic amount and antioxidant activities than Opuntia ficius-indica. Both lignins showed high cell viability (>96%) and cell proliferation. Activation signal was observed for both lignins with increase of ROS and cytosolic calcium levels, and changes in mitochondrial membrane potential. In addition, lignins induced high TNF-α, IL-6 and IL-10 production and reduced NO release. Therefore, these lignins present great potential to be used as molecules with a proinflammatory profile, being shown as a promising therapeutic agent., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Insoluble residue (INS) is a lignin-rich fraction of brewer's spent grain (BSG) that also contains β-glucan and arabinoxylan, the major constituents of dietary fiber. We investigated the effects of INS in diet-induced obese mice in terms of lipid metabolism and metabolic diseases. Male mice (C57bl6) were fed a high-fat diet (HFD), a HFD + 20% INS, a HFD + 20% cellulose (CEL), a HFD with a combination of 20% INS-CEL (1:1), or a control diet for 14 weeks. Insulin and glucose tolerance tests were performed after 12 weeks. Fasting plasma lipids, bile acid, and fecal bile acid were measured after 14 weeks of feeding, and tissues were collected for gene expression analysis. Body weight gain was significantly reduced with all fibers, but only INS and INS-CEL decreased fasting plasma low-density lipoprotein cholesterol and total cholesterol compared to HFD. CEL and INS-CEL significantly improved insulin resistance. Fecal bile acids were significantly increased by all fibers, but there was no change in plasma bile acid. Clostridium leptum was increased with all fibers, but universal bacterial diversity was only with INS and INS-CEL. In addition, INS significantly increased the abundance of Bacteriodes, while CEL decreased Atopobium and Lactobacillus. INS feeding significantly upregulated various genes of cholesterol and bile acid metabolism, such as Srebp2, Hmgcr, Ldlr, Cyp7a1, Pparα, Fxr, and Pxr, in the liver. INS, INS-CEL, and CEL significantly attenuated liver steatosis. Our results suggest that INS from BSG induced beneficial systemic changes in mice via gut microbiota, bile acids, and gene expression in the liver.

In the present study, lignin from eucalyptus was extracted with 80% alkaline dioxane (0.05 M NaOH) from ball-milled wood and subsequently fractionated by gradient acid precipitation from the filtrate. Meanwhile, the residual lignin was prepared by a double enzymatic hydrolysis process. The yield of the lignin extracted by alkaline dioxane (L A-2 ) was 29.5%. The carbohydrate contents and molecular weights of the gradient acid precipitated lignin fractions gradually decreased from 4.90 to 1.36% and from 7770 to 5510 g/mol, respectively, with the decline of the pH value from 6 to 2. Results from two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance (NMR) and 31 P NMR spectroscopy showed an evident reduction of β- O-4 ' linkages with the pH value decrease, while the contents of aliphatic -OH, phenolic -OH, and carboxylic groups displayed an increasing trend. Moreover, the residual lignin exhibited the highest molecular weight (11690 g/mol), the most abundant β- O-4 ' linkages (71.1%), and the highest S/G ratio (4.68).

Biomass pretreatment can improve the conversion efficiency of bioenergy production. Liquid hot water (LHW) pretreatment is a truly green pretreatment due to its zero chemical use, but has the disadvantages of low lignin removal and pseudo-lignin formation. A modified liquid hot water (MLHW) process based on in situ synthesis of deep eutectic solvent (DES) could efficiently improve delignification of Roystonea regia leaves (LR) and leaf sheaths (LSR). LSR was less recalcitrant than LR, and its characteristics of higher porosity (34.8%) and thinner cell walls (5.2 μm) for LSR contributed it higher lignin removal (53.6%) and lower choline chloride (ChCl) consumption (H 2 O-ChCl mass ratio of 2:1) than those (44.6% and 1:2) from LR. Moreover, a great improvement of 309.0% in bio-methane yield was achieved for the MLHW-treated LSR. In addition, in situ DES in MLHW had good biocompatibility with cellulase, microalgae, and yeast., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Lignin valorization is significantly hindered by the intrinsic heterogeneity of its complex structures and variability of biomass feedstocks. Fractionation of lignin can overcome these challenges by producing functionally distinct lignin cuts that can be further tailored to end products. Herein, lignin was extracted and depolymerized from poplar by the co-solvent enhanced lignocellulosic fractionation method with renewable THF to obtain CELF lignin. Several solvents were screened to separate soluble and insoluble fractions from the parent CELF lignin. The ethanol soluble portion was then fractionated into different molecular weight cuts via sequential precipitation of the lignin by reducing the concentration of THF. The physicochemical structures of different CELF lignin cuts were elucidated by GPC and NMR techniques. These results suggest that CELF lignin cuts with lower molecular weight contain progressively higher phenolic and carboxylic acid OH groups, which can be more suitable as green antioxidants than the parent lignin., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Corncob was successively pretreated by liquid hot water (LHW) and ethanol organosolv (EO) in an integrated process. LHW was performed at 200 °C for 30 min, and EO was performed using uncatalyzed ethanol-water solutions, according to a design of experiments. The effects of the most influential operational variables (ethanol concentration, temperature and time) on yield and chemical composition of the fractions were assessed. Results showed the factor with the greatest effect was ethanol concentration (p < 0.05), leading to a high-purity lignin (86.7%-93.1%) with a total phenolic content of around 25 mg GAE/g. Moreover, the solids recovered from the high ethanol concentration conditions presented the lowest lignin contents (15.4%-17.2%) with good preservation of cellulose (82.5%-88.6% of glucans). The lignin antioxidant capacity showed that all lignin samples presented radical scavenging activity (IC 50 of 0.17 mg/mL and 0.016 mg/mL on DPPH (2,2‑diphenyl‑1‑picrylhydrazyl) and ABTS (2,2'‑azino‑bis(3‑ethylbenzothiazoline‑6‑sulphonic acid) assays, respectively) with values close to the commercial antioxidant BHT. Moreover, the chemical (FTIR) and thermal (DSC and TGA) characterization showed lignins with similar properties that were compared with lignin from direct ethanol organosolv process. Results showed that the integrated process of LHW-EO was the most effective way to obtain lignin with high purity and antioxidant capacity., (Copyright © 2018 Elsevier B.V. All rights reserved.)

To study the differences in chemical composition analysis and spatial distribution of young Neosinocalamus affinis bamboo, we used the methods of standard of National Renewable Energy Laboratory and confocal Raman microscopy, respectively. It was found that the acid-soluble lignin and acid-insoluble lignin content showed an inverse relationship with the increasing bamboo age. Raman analysis revealed that Raman signal intensity of lignin in both the secondary cell wall and the compound middle lamella regions showed a similar increase trend with growth of bamboo. In addition, eight hemicellulosic fractions were obtained by successively treating holocellulose of the 2-, 4-, 8-, and 12-month-old Neosinocalamus affinis bamboo culms with DMSO and alkaline solution. The ratio of arabinose to xylose of hemicelluloses was increased with the growth of bamboo. FT-IR and NMR analyses revealed that DMSO-soluble hemicelluloses of young bamboo culms are mainly composed of highly substituted xylans and β-d-glucans.