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A practical method for the preparation of lignin derivatives-light-colored bio-based particles (LC-BP) via the modification of hexamethylene diisocyanate (HDI) is presented in this work. In the mixed EtOH/H 2 O system, the change of solvent polarity induced the self-assembly of the lignosulfonate (LS) with the hydrophobic chromophores encapsulated inside the particles. The color of LS was reduced by the polymerization between the isocyanate groups (-N=C=O) of HDI and hydroxy groups of LS. Compared with the typical lignin-based adsorbent preparation process in the past, this is a simple, direct, and efficient preparation method and the synthetic LC-BP has good chemical stability and resistance to heat, acid and alkali. This effectively solves the problem that LS has high water solubility and is difficult to use directly for wastewater treatment. To investigate the properties, the synthetic LC-BP was characterized by SEM, specific surface area, L*a*b* (CIELAB) color space, FT-IR, XPS, and TGA. The results showed that the LC-BP exhibited obvious advantages in color reduction with a low CIE-L* value. The LC-BP exhibits a scale-like intercalation structure, which makes it a promising candidate for adsorbing tetracycline (TC) from wastewater. The conditions of pH, adsorbent dosages, adsorption time, and initial TC concentration were investigated, and the adsorption performance of LC-BP for TC was significantly better than that of conventional polyurethane particles (PP). The adsorption fitted the Langmuir model and there were hydrogen bonding, π-π conjugated binding, and electrostatic attraction during the absorption process. The adsorption capacity was up to 53.1 mg/g, and the removal rate was 67 %. The utilization of LC-BP, a low-cost, effective, and renewable resource derived from natural biomass, holds immense practical and economic potential in wastewater treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Thehighly efficient utilization of lignin is of great importance for the development of the biorefinery industry. Herein, a novel "core-shell" lignin nanoparticle (LNP) with a diameter of around 135 nm was prepared, after the lignin was isolated from the effluent of formic acid fractionation via dialysis. In an attempt to endow composite materials with vital functionalities, the LNP was added to the starch film and the starch/polyvinyl alcohol (PVA) or starch/polyethylene oxide (PEO) composite film. The results showed that the hydrophobicity performance of the synthesized films was enhanced significantly. Specifically, the dynamic water contact angle value of the starch/PVA composite film with 1% (wt) addition of LNPs could be maintained as high as 122° for 180 s; the starch/PEO composite film also achieved an excellent water contact angle above 120°. The addition of LNPs promoted the formation of some rough structures on the film surface, as shown by the scanning electron microscopy images, which could repel the water molecules efficiently and are closely related to the enhanced hydrophobicity of the starch film. What is more, the as-prepared LNP conferred strengthened thermal stability and ultraviolet blocking properties on the starch composite film. The structural combination of the polymer film with LNPs holds the promise for providing advanced functionalities to the composite material with wide applications.

During the traditional autohydrolysis, formation and deposition of "pseudo-lignin" and lignin droplets on the surface of biomass had a detrimental effect on the subsequent biomass conversion. In this study, isothermal phase separation was introduced into autohydrolysis, and the effects of isothermal phase separation on the dissolution of components and enzymatic hydrolysis of bamboo were studied. The research showed that isothermal phase separation after autohydrolysis without cooling had an effective reduction in the deposition of "pseudo-lignin" and lignin droplets on the residues surface. After isothermal phase separation, the contents of sugar (14.05 g/L) and lignin (6.16 g/L) in pre-hydrolysates increased by 20% and 19% compared with control, respectively. Moreover, the efficient removal of "pseudo-lignin" and lignin droplets from cell wall surface could further promote the biological conversion of pretreated biomass (22% higher than that of control) during the subsequent enzymatic hydrolysis., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Integrated fractionation process based on autohydrolysis (H) and subsequent formic acid delignification (FAD) has been considered as an effective strategy to separate the main lignocellulosic components in view of the biorefinery. For the better understanding of the structural changes of the lignin during the integrated process, the fractionated aspen lignins were thoroughly characterized by Fourier transform infrared (FT IR), 13 C, two-dimensional heteronuclear single quantum coherence (2D-HSQC) and 31 P nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC), and thermogravimetric analysis (TGA). Compared to the milled wood lignin (MWL), the fractionated lignins had higher amounts of phenolic OH groups as due to the cleavage of β-O-4 linkages and less alcoholic OH groups mainly due to the esterification of the aliphatic OH groups by formic acid. Demethylation action of the lignin was not significant during the FAD process. More syringyl-propane (S) units were extracted during the H-FAD process than guaiacyl-propane (G) units resulting in a higher S/G ratio and more OCH 3 in the fractionated lignins. Furthermore, autohydrolysis of aspen at higher temperature led to more condensation of the fractionated lignins which exhibited higher molecular weight and more β-5 and β-β linkages. The fractionated lignins exhibited high purities due to the breakage of the lignin-carbohydrate bonds., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The removal of lignin is important to the recovery of saccharides from the pre-hydrolysis liquor (PHL) in kraft-based dissolved pulp production. A one-step process for lignin removal from PHL via treatment with horseradish peroxidase (HRP) in the presence of Ca 2+ was proposed, and its principle was studied. The results demonstrated synergy between HRP and Ca 2+ in lignin removal from PHL, whereas NH 4 had little effect on lignin removal. HRP treatment in the presence of 60 mmol/L of Ca + resulted in a lignin removal of 64.8% accompanied by a saccharide loss of 14.2%. HRP catalyzed both the polymerization and depolymerization of the lignin in the PHL. The HRP-catalyzed lignin polymerization rendered some lignin insoluble enabling it to be directly removed. The HRP-catalyzed depolymerization of lignin decreased its molecular weight with an evident increase in its carboxyl content. The insoluble complexes formed between the lignin with carboxyl and the Ca 2+ facilitated the removal of the depolymerized lignin.2+ facilitated the removal of the depolymerized lignin., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Prehydrolysis of lignocellulose produces abundant hemicellulose-derived saccharides (HDS). To obtain pure HDS for application in food or pharmaceutical industries, the prehydrolysis liquor (PHL) must be refined to remove non-saccharide compounds (NSC) derived from lignin depolymerization and carbohydrate degradation. In this work, activated carbon (AC) adsorption was employed to purify HDS from NSC with emphasis on adsorption selectivity. The adsorption isotherms showed the priority of NSC to be absorbed over HDS at low AC level. However, increase of AC over 90% of NSC removal made adsorption non-selective due to competitive adsorption between NSC and HDS. Size exclusion chromatography showed that the adsorption of oligomeric HDS was dominant while monomeric HDS was inappreciable. The limited selectivity suggested that AC adsorption is infeasibility for HDS purification, but applicable as a pretreatment method., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Saccharides and lignin components in prehydrolysis liquor (PHL) from kraft-based dissolving pulp production was characterized after being fractionated using membrane filtration. The results showed that the membrane filtration provided a method for organics fractionation with considerable recovery rate, but exhibited some disadvantages. Besides the limited ability in purifying oligosaccharides (OS) due to the overlaps of molecular weight distribution with lignin components, the membrane filtration could not improve the homogeneity of OS as indicated by the analysis of chemical compositions and the degree of polymerization (DP), which may be ascribed to the linear conformation of OS. The characterization of lignin components indicated a great potential for polymer industry because of the remarkable content of phenolic hydroxyl groups (PhOH), especially for low molecular weight (LMW) fraction. It was concluded the organics in PHL provided streams of value-added chemicals. However, the practical significance thereof can be realized and maximized only when they are successfully and completely fractionated., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The specific elimination of lignin derivatives from wood hydrolysate without sugar loss has great practical significance to biorefinery and bioenergy. In the present study, a process consisting of calcium hydroxide and anion exchange resin treatments was developed for the purpose of selective removal of lignin from wood prehydrolysis liquor (PHL). Particular emphasis was made on the ionization of phenolic lignin, and the subsequent binding to metallic salts. It was observed that phenolic hydroxyl groups (PhOH) in lignin played an important role in lignin removal. The results showed that up to 95.2% lignin was removed from PHL with 78.8% sugar recovery. This suggested that the proposed process is highly specific to lignin, and therefore can be envisaged as a great contribution to wood-sugar production or bioenergy conversion., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Hot water extraction is an important strategy of wood fractionation, by which the hemicelluloses can be separated for value-added products, while the residual solid can still be processed into traditional wood products. In this study, a combined process consisting of specific lignin precipitation and dialysis was proposed to recover hemicellulosic oligosaccharides (OS) from hot water extract (HWE). The results showed that polyaluminium chloride (PAC) precipitation was highly specific to large molecular lignin, leading to 25.1% lignin removal with negligible OS loss through charge neutralization mechanism. The separation was further enhanced by dialysis, reaching 37.6% OS recovery from HWE with remarkable purity of 94.1%. By the proposed process, 56.36 g OS, mainly xylooligosaccharides with two fractions of 5.2 and 0.51 kDa was recovered from one kg dried wood. This process can be envisaged as a great contribution to wood biorefinery., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

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

Artificial antioxidants are synthesized from fossil sources and are now widely used in the polymer, food, and cosmetics industries. The gradual depletion of fossil resources makes it practically significant and necessary to produce green antioxidants from renewable lignocellulosic resources. Herein, short‐time hydrothermal (STH) treatment was developed for production of lignin‐derived polyphenol antioxidants (LPAs) from poplar wood under conditions of high temperature and high pressure. LPA yields from 21.5 to 37.6 % on the basis of lignin in untreated wood were obtained by STH treatments as result of lignin depolymerization at 190–200 °C and 10 MPa in 5–8 min. Depolymerization reactions were confirmed by the much lower molecular weight of LPA (1076 g mol−1) than that of native lignin (4094 g mol−1). NMR spectroscopy revealed the structural features of lignin in the isolated LPA, namely syringyl and guaiacyl units with well‐preserved interunit linkages. A Folin–Ciocalteu assay indicated that each LPA molecule contained 5.4 phenolic hydroxyl groups on average, much more than other technical lignins. The remarkable antioxidant ability of LPA was verified by the radical‐scavenging index of 53.5–67.3, much higher than 0.2–11.1 of the commercial antioxidants butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA). STH treatment only requires water and heat for production of high‐value antioxidant, which provides a green and sustainable method for the utilization of lignocelluloses. [ABSTRACT FROM AUTHOR]

Whole valorization of carbohydrate and lignin from biomass was achieved by rapid flow‐through fractionation (RFF) within 15 min. Wheat straw was effectively deconstructed into its principle components without degradation by using easily recyclable aqueous formic acid (72 wt %) at 130 °C. The obtained cellulose‐rich solid showed a nearly complete glucan recovery and 73.8 % glucose conversion after enzymatic hydrolysis. Xylan also reached full recovery with negligible furfural formation with a sum of 80 % of oligo/mono xylose in spent liquor and 20 % of xylan remaining in the solid. Up to 75.4 % lignin was dissolved in the spent liquor and further fractionated into water‐insoluble (WIL) and water‐soluble lignin (WSL) by dilution with water. WIL showed a non‐condensed and well‐preserved structure with 84.5 % β‐O‐4 remaining, which is believed to be beneficial for catalytic conversion into low‐molecular‐weight chemicals and fuels. The concentration of employed formic acid was below the formic acid/water azeotrope, and therefore the reaction medium could be restored through simple distillation. Together with the joint valorization of lignin and carbohydrates, the presented RFF is a promising process for sustainable biorefinery. Whole valorization of carbohydrate and lignin from biomass is achieved by rapid flow‐through fractionation within 15 min. Wheat straw is effectively deconstructed into its principle components without degradation by using easily recyclable aqueous formic acid (72 wt %) at 130 °C. The obtained cellulose‐rich solid shows a nearly complete glucan recovery and 73.8 % glucose conversion after enzymatic hydrolysis. [ABSTRACT FROM AUTHOR]

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

Abstract: Old newsprint (ONP) could be deinked with laccase–violuric acid system (LVS). To study the mechanism of LVS deinking, lignins from the control and LVS-deinked pulp were isolated and characterized by chemical, spectroscopic and chromatographic methods. The molecular weight change of lignin was tracked by gel permeation chromatogram (GPC), and structural changes in lignin extracted from the control and LVS-deinked pulps were characterized by elemental analysis, functional groups measurement, FT-IR, 1H NMR and 1H–13C correlation 2D NMR. The experimental results showed that the molecular weight of lignin from LVS-deinked pulp was lower than that of lignin from the control pulp. The contents of free phenolic hydroxyl groups and methoxyl groups of lignin from LVS-deinked pulp decreased, while the contents of carboxyl and carbonyl groups increased. Guaiacyl units in lignin were oxidized by LVS. Stilbene and 5–5′ substructures in lignin were stable to LVS treatment, while β-O-4 and β–β substructures were partially destroyed during the LVS deinking. According to structural changes in lignin, the mechanism of LVS deinking was deduced. [Copyright &y& Elsevier]

Highly hydrophobic fabrics by chelating lignin (alkali lignin, sodium lignin sulfonate and formic acid lignin) with metal ions (Fe3+, Fe2+ and Cu2+) were prepared with the surface wettability from superhydrophilic to highly hydrophobic. The lignin/metal chelated particles are in-situ deposited onto the fabric surface using dip-coating. Different lignin/metal ion system influenced the construction of hierarchical surface roughness and energy of fabrics greatly. Specially, the formation of homogeneous spherical particles on surface contributed to the minimal contact area of water droplets and fabric, and thus avoiding their adherence. The surface morphology results showed that the active groups of lignin is closely related with the surface roughness. It was found that the alkali (AL)/FeⅢ@cotton fabric achieved a maximum water CA value of 149.9° and a low surface energy of 1.90 mN/m. Its oil-water separation efficiency was higher than 99.9% and the resultant AL/FeⅢ@cotton fabric owned an excellent stability and suitability under harsh conditions. Collectively, this work is greatly significant for achieving the high-value utilization of lignin in wastewater treatments. [Display omitted] ● In-situ deposition of lignin/metal ion lowered the surface energy of fabrics. ● Phenolic hydroxyl content of lignin affected the size of lignin/metal chelates. ● Deposited lignin/metal chelates influenced the durable hydrophobicity of fabrics. ● Al/Fe3+ conferred the fabric highest hydrophobicity with the WCA value of 149.9°. ● The resultant fabric exhibited an excellent oil-water separation and stability. [ABSTRACT FROM AUTHOR]

The removal of colloidal particle and lignin from a pre-hydrolysis liquor (PHL) of biomass is essential for its processing as well as for the value-added utilization of saccharides in the PHL. In this paper, pectinase was used to treat an aspen PHL obtained by pre-hydrolysis at 160 °C, and a novel process in which pectinase treatment was followed by cationic polymer flocculation to enhance colloidal particle and lignin removal was investigated. The results showed that pectinase treatment caused an approximately 50% decrease in the cationic demand of the aspen PHL. For the controlled PHL, approximately 68 mg/L poly-dimethyl diallyl ammonium chloride (pDADMAC) was needed to remove nearly all of the colloidal particles with 40.3% maximum lignin removal; for the enzyme-treated PHL, only approximately 34 mg/L pDADMAC was needed to remove nearly all of the colloidal particles with 43.3% lignin removal. In addition, the enzyme treatment decreased the loss of saccharides during subsequent pDADMAC treatment at the concentration necessary for maximum lignin removal. [ABSTRACT FROM AUTHOR]

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

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

A combined process of lime treatment and mixed bed ion exchange was proposed to separate hemicellulose-derived saccharides (HDS) from prehydrolysis liquor (PHL) of lignocellulose as value added products. The optimization of lime treatment achieved up to 44.2% removal of non-saccharide organic compounds (NSOC), mainly colloidal substances, with negligible HDS degradation at 0.5% lime level and subsequent neutralization by phosphoric acid. The residual NSOC and calcium ions in lime-treated PHL were eliminated by mixed bed ion exchange. The breakthrough curves of HDS and NSOC showed selective retention toward NSOC, leading to 75% HDS recovery with 95% purity at 17 bed volumes of exchange capacity. In addition, macroporous resin showed higher exchange capacity than gel resin as indicated by the triple processing volume. The remarkable selectivity of the combined process suggested the feasibility for HDS separation from PHL. [ABSTRACT FROM AUTHOR]

Prehydrolysis of wood biomass prior to kraft cooking provides a stream containing hemicellulose-derived saccharides (HDSs) but also undesired non-saccharide compounds (NSCs) that were resulted from lignin depolymerization and carbohydrate degradation. In this study, a combined process consisting of lime treatment, resin adsorption, and gel filtration was developed to separate HDSs from NSCs. The macro-lignin impurities that accounted for 32.2% of NSCs were removed by lime treatment at 1.2% dosage with negligible HDSs loss. The majority of NSCs, lignin-derived phenolics, were eliminated by mixed bed ion exchange resin, elevating NSCs removal to 94.0%. The remaining NSCs, furfural and hydroxymethylfurfural, were excluded from HDSs by gel filtration. Chemical composition analysis showed that xylooligosaccharides (XOS) with the degree of depolymerization from 2 to 6 accounted for 28% of the total purified HDSs. [ABSTRACT FROM AUTHOR]

Ethanol extraction of lignocellulosic biomass under mild conditions has re-attracted considerable attention since a light-colored lignin with low molecular weight can be obtained. Unfortunately, the yield of isolated lignin for the ethanol extraction process is very limited. To enhance the extraction efficiency of lignin from poplar, ultrasound was used to assist the ethanol extraction and the isolated lignin was analyzed in terms of structure features and functional properties. As expected, increasing the ultrasonic power and ultrasonic time led to higher lignin yields during the ultrasound-assisted ethanol extraction (UAEE) process. The chemical structure of the isolated lignin (UAE-L) was almost completely retained, the C-O (mainly β-O-4) linkages in the lignin only exhibited a slight decrease, while the C-C (β-β, β-5, and β-1) linkages were nearly unchanged. The UAE-L was light in color and had more phenolic hydroxyl groups, less carbohydrate impurities, lower molecular weight and narrower polydispersity as compared to the poplar MWL. The UAE-L could scavenge more 2,2-diphenyl-1-picrylhydrazyl radicals (DPPH·), displaying a stronger antioxidant activity. Moreover, the UAE-L showed good UV-absorbing properties in both UVA and UVB regions. These results indicated that the UAE-L has great potential for replacing the commercial synthesized antioxidant and anti-UV ingredients. The overall scheme of the isolation process of lignin from poplar by ultrasonic-assisted ethanol extraction (UAEE). [Display omitted] • Ultrasound was employed to enhance ethanol extract of lignin. • Light-colored lignin with abundant phenolic -OH and low molecular weight was obtained. • Lignin unit with less ortho- methoxy substitutions was preferentially released. • UAE-L showed good antioxidant activity and broad-spectrum UV-absorption capacity. [ABSTRACT FROM AUTHOR]

Abstract: An approach aiming at improving paper properties is to use laccase to copolymerize low-molecular weight phenols with the pulp before papermaking. The addition of methyl syringate (MS) gave a twice wet tensile index of unbleached kraft pulp with laccase treatment but had little effect on the dry tensile index and substantially decreased the brightness of pulp. The radical concentration in laccase-treated fibers increased up to 2.5 times of that in control sample after 60min. The radical concentration in laccase/MS-treated fibers increased up to 20 times of that in control sample within 2min, and a highest radical concentration (increased by near 65 times) was obtained after 40min. A strong agglutination of large-area fibers in handsheet was observed after laccase/MS treatment. The surface lignin coverage of the laccase-treated fibers increased from 54.96% (control) to 59.36%, while that of the laccase/MS-treated fibers increased only up to 55.22%. It is suggested that the graft of MS on fiber and degradation of surface lignin occurred simultaneously. The addition of MS can enhance the activation of fibers and extend the enzymatic oxidation of lignin within the cell wall. An increased bonding area of fibers resulting from interaction of laccase, MS and fibers via radical-coupling reaction maybe account for the significantly improved wet strength of pulp. [Copyright &y& Elsevier]