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The utilization of lignin in material fabrication has garnered significant attention despite its complex structure that greatly limits its applications. This study reports a green method for grading and modifying lignin to prepare stable hydrophobic coatings via the solvent/anti-solvent (ethanol/water) self-assembly method. First, the formic acid lignin particle (FLP) is prepared and the underlying mechanism is primarily ascribed to the hydrogen bonding, π–π interactions among aromatic groups within and between molecules, and hydrophobic interactions. The lignin nanoparticles were utilized to chelate with metal ions (iron) in order to obtain the stable hydrophobic coatings using the special nanostructures of FLP. This hydrophobic coating could be applied to different substrates (blocks, straw, and fabric). The cotton fabric exhibited an initial water contact angle (WCA) that increased from 73.4° to 129.6°, and excellent chemical and physical hydrophobic performance. Moreover, this coating has strong self-cleaning ability and could be used for oil–water separation. In this newly proposed fabrication, ethanol can be recovered in the preparation of lignin nanoparticles, which makes the green and facile preparation of a stable hydrophobic coating possible. Additionally, this work is important in upgrading formic acid lignin by controlling the polarity into value-added hydrophobic materials via green classification. [ABSTRACT FROM AUTHOR]

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

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), 13C, two-dimensional heteronuclear single quantum coherence (2D-HSQC) and 31P 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. • Lignin with high phenolic OH and OCH 3 and high purity was obtained. • Aliphatic OH group was highly esterified by formic acid. • β-O-4 cleavage accompanied by formation of condensed aromatic structure • Autohydrolysis led to higher molecular weight and less formate ester in lignin [ABSTRACT FROM AUTHOR]

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 Ca2+ was proposed, and its principle was studied. The results demonstrated synergy between HRP and Ca2+ in lignin removal from PHL, whereas NH 4 + had little effect on lignin removal. HRP treatment in the presence of 60 mmol/L of Ca2+ 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 Ca2+ facilitated the removal of the depolymerized lignin. • A new one-step process for effective lignin removal from PHL was proposed. • Synergy existed between HRP and Ca2+ in lignin removal from PHL. • HRP treatment in the presence of 60 mmol/L of Ca2+ yielded 64.8% lignin removal. • HRP treatment increased the carboxyl content of soluble lignin in PHL. • Complexes formed between Ca2+ and the carboxyl of soluble lignin to facilitate lignin removal. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • A practical method for the preparation of light-colored lignin • The theoretical basis of lignin-based biomacromolecular compounds was proposed. • Rearrange chromophoric groups of lignin by isocyanate modified • The product can be used as efficient adsorbent for colored wastewater. [ABSTRACT FROM AUTHOR]

The majority of current oral drugs are hydrophobic, and have the toxic side effects to the gastrointestinal tract, which limit their therapeutic efficacy. In order to improve the performance of drug formulations, the development of new functional materials is crucial for the technological breakthroughs in the pharmaceutical industry. The antimicrobial and antioxidant properties of lignin nanoparticles (LNPs) give them great potential for application in this field. LNPs consist of a hydrophilic shell and hydrophobic core, which is particularly suitable for the capsulation of hydrophobic drugs, and then it would increase the stability and solubility of drugs and reduced the irritation to the stomach. In this study, alkali lignin (AL) was fractionated by 80% methanol to obtain targeted MAL with low molecular weight, high phenolic hydroxyl content and good homogeneity. The LNPs was prepared by quaternization modification of MAL and self-assembling in an ethanol/water mixture. Their application in the hydrophobic oral drug delivery system was evaluated and Ibuprofen (IBU) was used as a drug pattern. The effect of solvent exchange time (24 h, 36 h, 48 h and 60 h) on the formation process of IBU-loaded LNPs (IBU-LNPs) was investigated. The in vitro release experiments were conducted and it revealed that IBU release occurred priority in the intestine rather than the stomach, which were meeting the release requirements of ideal oral carrier. In addition, IBU-LNPs showed non-cytotoxic against the L929 cells and improved the bioavailability of IBU drugs. Therefore, this work proposes a preparation method of the smart lignin nanoparticle by screening characteristic lignin with higher reactivity and by modulating the solvent exchange time during the preparation process. Overall, LNPs showed the great potential of application in pharmaceuticals industry and was demonstrated a promising and green product. • Lignin nanoparticles (LNPs) were prepared with the objective of evaluating their application as a novel oral drug delivery system. • The novel LNPs have an optimal size, high encapsulation efficiency, and a sustained pattern of Ibuprofen release in the simulated intestinal fluid, and excellent stability in the gastric condition. • LNPs increase the bioavailability of Ibuprofen and show non-cytotoxic against the normal cells. [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]

[Display omitted] • Poplar was pretreated by reusable organic solvent under mild temperature (≤100 °C). • Almost all hemicelluloses and part of lignin was extracted with cellulose retained. • Sulfonic acid groups were introduced into lignin structure remained in substrates. • 89% improved glucose conversion compared with that of non-sulfonated substance. • New strategy is exploited to realize sulfonation and promote biomass bioconversion. Biomass pretreatment is an essential strategy to overcome biomass recalcitrance and promote lignocellulosic bioconversion. Here, a reusable organic solvent system (formic acid-methanesulfonic acid) was explored to pretreat poplar under a mild temperature (below 100 °C). The results showed that the co-solvent system could extract basically complete hemicelluloses and part of lignin with original cellulose retained in the pretreated substrates. Meanwhile, sulfonic acid groups were introduced into lignin structure remained in the substrates. The glucose conversion yield of the substrates with a higher concentration of sulfonic acid groups (13.2 mmol/kg) reached 45.9 % by reducing the hydrophobic interaction between lignin and cellulase, showing 89.3 % improvement compared with that of the substrates treated with single formic acid. This progressive study aimed to develop a new strategy to realize sulfonation and promote enzymatic hydrolysis of substrates by using mild organic solvent pretreatment. [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]

[Display omitted] • Pre-hydrolysis is considered as a promising technology in the biorefinery process. • "Pseudo-lignin" were formed and deposited on biomass surface during pre-hydrolysis. • The surface-deposits could be removed efficiently by isothermal phase separation. • More sugars were extracted by interrupting the formation of "pseudo-lignin". • The efficient removal of surface-deposits improved subsequent enzymatic hydrolysis. 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. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lignin recovery from PHL and adsorbent preparation was achieved in one step. • The lignin was modified and recovered from PHL via HRP treatment. • Lignin recovered from PHL by HRP treatment was a good adsorbent for MB removal. • The maximum MB adsorption capacity of EML was 241.1 mg/g at 308 K. The lignin in PHL could be modified and recovered from pre-hydrolysis liquor (PHL) by horseradish peroxidase (HRP) treatment. The enzyme-modified lignin (EML) separated from PHL was used to adsorb and remove methylene blue (MB) from a model dye effluent; the adsorption performance of EML was studied. The results indicated the carboxyl content of the lignin in PHL increased by HRP treatment, and the EML removed from PHL had a carboxyl content of 0.69 mmol/g and a BET surface area of 25.6 m2/g. With the increase of pH, the adsorption capacity of EML obviously increased. The maximum MB adsorption capacity of EML was 210.2 mg/g and 241.1 mg/g at 298 K and 308 K, respectively. The fitting results revealed that the equilibrium adsorption isotherms and adsorption kinetics followed the Langmuir model and pseudo-second-order model, respectively. [ABSTRACT FROM AUTHOR]