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Considering the severity of global environmental issues, biomass-derived products have received significant attention as alternatives to foster sustainability and eco-friendliness. The use of metal nanoparticle catalysts for dye decomposition is emerging as a promising approach for environmentally friendly dye removal. In this study, an aminosilane-modified lignin (AML)/silver nanoparticle (AgNP) composite was fabricated and used as a hydrogenation catalyst. The AgNPs were well dispersed on the AML surface and formed strong bonds within the AML/AgNP complex. AML also served as an effective reducing and capping agent for Ag(I) ions. The AML/AgNPs were found to be an efficient catalyst with excellent dye degradation ability and easy reusability. Biomass-derived lignin can be used as a reducing and capping agent for metals and this complex can be used as a high-value bio-catalyst for wastewater remediation., 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 © 2024 Elsevier B.V. All rights reserved.)

Kraft lignin (KL) holds significant potential as a renewable resource for the development of innovative materials that are currently not fully utilized. In this study, a novel iminated lignin (IL) was synthesized by grafting primary amine lignin (N-KL) onto salicylaldehyde. The effects of the dosage and reaction temperature on the nitrogen content of N-KL were evaluated. The maximum nitrogen content in N-KL reached to 3.32 %. Characterization by spectroscopy techniques (FT-IR, XPS, and NMR), elemental analysis, and gel permeation chromatography confirmed the imination of lignin. Additionally, the antioxidant activity of the lignin samples was investigated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability. Moreover, the DPPH radical scavenging capacity of IL-6 (IC 50  = 38.6 ± 3.9 μg/mL) was close to that of commercial antioxidant butylated hydroxytoluene (BHT) (IC 50  = 37.7 ± 4.5 μg/mL). Furthermore, the adsorption equilibrium results indicated that IL-6 had a maximum uptake of 115.6 mg/g Pb 2+ , which was 3.2-fold higher than that of KL. Kinetic adsorption experiments suggested that IL-6 adsorption follows a pseudo-second-order model. Therefore, the synthesized iminated lignin is a promising candidate for the development of environmentally friendly materials with applications as an antioxidant and lead-ion adsorbent., 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 © 2024 Elsevier B.V. All rights reserved.)

In this study, a novel zwitterion-substituted lignin (ZL) containing amino and sulfonic acid groups was synthesized, and ZL/Nafion composite membranes were fabricated as proton exchange membranes. Kraft lignin was modified using an aminosilane and 1,3-propanesultone via a continuous grafting reaction to provide zwitterionic moieties. Chemical structural analyses confirmed the successful introduction of the zwitterion moiety into lignin. In particular, the surface charge of ZL is positive in an acidic medium and negative in a basic medium, suggesting that ZL is a zwitterionic material. ZL was incorporated into a Nafion membrane to enhance its ion exchange capacity, thermal stability, and hydrophilicity. The proton conductivity of ZL/Nafion 0.5 %, 151.0 mS/cm, was 55.3 % higher than that of unmodified ML (methanol-soluble lignin)/Nafion 0.5 % (97.2 mS/cm), indicating that the zwitterion moiety of ZL enhances the proton transport ability. In addition, oxidative stability evaluation confirmed that ZL/Nafion 2 % was chemically more durable than pure Nafion. This confirmed that using lignin as a membrane additive yielded positive results in terms of chemical durability and oxidation stability in Nafion. Therefore, ZL is expected to be utilized as a multifunctional additive and exhibits the potential for fuel cell applications., 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 The Authors. Published by Elsevier B.V. All rights reserved.)

In this work, silanized and aminated lignin (SAL) was synthesized in one step and its adsorption of Congo red and Cu(II) ions in aqueous solution was explored. Lignin was subjected to amine-silanization with (3-aminopropyl) triethoxysilane (APTES). Structural characterization substantiated successful amine-silanzation of lignin and formation of multi-layer APTES intermolecular crosslinked structure. The prepared SAL (nitrogen content = 6.1%) exhibited enhanced molecular weight, thermal stability, and water- and organic solvent-resistance properties. Additionally, the present of the porous structure of particle surface and an increase in the specific surface area and zeta potential promoted the accessibility of contaminants to the effective adsorption sites of SAL. Adsorption experiments showed that both Congo red and Cu(II) ion could be completely removed at original pH value, and their adsorption involved electrostatic attraction and complexation, respectively. The adsorption isotherms and kinetics were well described by the Langmuir and pseudo-second-order equations, respectively. The results showed that SAL is a promising adsorbent for the treatment of effluents., (Copyright © 2020 Elsevier B.V. All rights reserved.)

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.)

Low-cost, high-performance electrodes are highly attractive for practical supercapacitor applications. MnO 2 -deposited carbon nanofiber mats (MnO 2 -CNFMs) are prepared for use as binder-free supercapacitor electrodes. MnO 2 is deposited on the mats in situ by hydrothermally decomposing aqueous KMnO 4 , leading to the formation of nanocrystals of MnO 2 . The MnO 2 -CNFM electrode produced with 38.0μmol KMnO 4 (this electrode) shows a high specific capacitance of ~171.6F·g -1 at a scan rate of 5mV·s -1 . Moreover, a symmetric supercapacitor with the electrode exhibits a specific capacitance of 67.0F·g -1 , an energy density of 6.0Wh·kg -1 and a power density of 160W·kg -1 at a special current of 0.1A·g -1 . Further, the symmetric supercapacitor displays excellent cycling stability, retains approximately 99% of the capacitance after 1000cycles. The simplicity and ease of preparation of the MnO 2 -CNFMs as well as their suitability for use in coin-type supercapacitor cells make them ideal for application in cost-effective and high-performance electrodes for supercapacitors., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The graft copolymerization of acrylonitrile (AN) onto methanol-soluble kraft lignin (ML) was achieved through a two-step process in which AN was first polymerized with an α,α'-azobisisobutyronitrile initiator, followed by radical coupling with activated ML. A carbon nanofiber material was obtained by electrospinning a solution of this copolymer in N,N-dimethylformamide, then subjecting it to a heat treatment including thermostabilization at 250°C and subsequent carbonization at 600-1400°C. Increasing the carbonization temperature was found to increase the carbon content of the resulting carbon nanofibers from 70.5 to 97.1%, which had the effect of increasing their tensile strength from 35.2 to 89.4 MPa, their crystallite size from 13.2 to 19.1 nm, and their electrical conductivity from ∼0 to 21.3 Scm(-1). The morphology of the mats, in terms of whether they experienced beading or not, was found to be dependent on the concentration of the initial electrospinning solution. From these results, it is proposed that these mats could provide the basis for a new class of carbon fiber material., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Milled wood lignin was subjected to heat treatment between 150 and 300°C to understand the pattern of its structural modification and thermal properties. When the temperature was elevated with interval of 50°C, the color of the lignin became dark brown and the lignin released various forms of phenols from terminal phenolic groups in the lignin, leading to two physical phenomena: (1) gradual weight loss of the lignin, up to 19% based on dry weight and (2) increase in the carbon content and decrease in the oxygen content. Nitrobenzene oxidation and (13)C NMR analyses confirmed a cleavage of β-O-4 linkage (depolymerization) and reduction of methoxyl as well as phenolic hydroxyl group were also characteristic in the lignin structure during heat treatment. Simultaneously with lignin depolymerization, GPC analysis provided a possibility that condensation between lignin fragments could also occur during heat treatment. TGA/DTG/DSC data revealed that thermal stability of lignin obviously increased after heat treatment, implicating the structural rearrangement of lignin to reduction of β-O-4 linkage as well as accumulation of CC bonds., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Copolymerization of N-isopropylacrylamide (NIPAM) with technical hardwood kraft lignin (HWKL) was achieved by atom transfer radical polymerization (ATRP) using a selectively modified lignin-based macroinitiator. The degree of polymerization (DP) of polyNIPAM graft side chains was affected by varying the ratio of the DMF/water solvent system from 5:0 to 0:5, and an estimated DP(NIPAM) of >40 was obtained using a ratio of 1:4 (v/v). The thermal decomposition temperature of the lignin-g-polyNIPAM copolymers significantly increased with increasing DP(NIPAM). Likewise, the solubility of the lignin-g-polyNIPAM copolymers in water changed depending on copolymer structure. In both the water-soluble and suspended copolymers, at temperatures above 32 degrees C, the g-polyNIPAM component underwent the typical hydrophilic-to-hydrophobic transition, resulting in the precipitation of the copolymer.

The development of eco-friendly, sustainable, biodegradable, and biocompatible green biopolymer composites is becoming increasingly important. In this study, acetoacetylated lignin (ATL) was obtained via an eco-friendly, facile one-step synthesis reaction, and chitosan (CS)-containing ATL films (CSL) were prepared. The chemical structural analysis of ATL confirmed that the acetoacetyl groups were successfully grafted onto kraft lignin (KL). ATL with adequate acetoacetyl groups exhibited enhanced molecular weight and antioxidant and ultraviolet (UV)-shielding properties. In particular, ATL, with a half maximal inhibitory concentration (IC 50) of 23.8 μg·mL−1, exhibited superior antioxidant activity than butylated hydroxytoluene (38.3 μg·mL−1) and KL (50.0 μg·mL−1). When ATL was incorporated into the CS solution to prepare biofilms, the antioxidant activity, UV-shielding property, water resistance, and thermal stability of the CSL greatly improved. Notably, the UV-A and UV-B shielding properties of the 2 % CSL were 130 % and 78 % higher than those of the pure CS film, respectively. Therefore, ATL designed with lignin-derived multifunctional properties has potential applications as an antioxidant and UV-shielding bio-additive and shows significant prospects in food packaging and biomedical applications. [Display omitted] • Acetoacetylated lignins (ATLs) were synthesized under solvent-free conditions. • ATL had an IC 50 value of 23.8 μg·mL−1, exhibiting excellent antioxidant activity. • Chitosan/ATL composite film (CSL) exhibited significant antioxidant activity. • CSL exhibited excellent UV shielding properties. • CSL exhibited improved thermal stability and water resistance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Branched aminated lignin-based hydrogels (BALH) were successfully fabricated. • Hydrogel has tunable pores and surface charge depending on the lignin and PEI ratio. • The adsorption capacity for MO reached approximately 900–930 mg/g. • BALH can selectively adsorb cationic/anionic dyes. • BALH maintain high removal efficiency after 10 recycles and continuous adsorption. This study introduces a branched aminated lignin-based hydrogel (BALH) designed for the efficient removal of ionic dye pollutants from wastewater. BALH was fabricated using lignin and branched polyethylenimine with poly(ethylene glycol) diglycidyl ether as a crosslinker. BALH exhibited enhanced chemical durability and physical stability; it formed a robust three-dimensional network through polyelectrolyte complexation and chemical crosslinking. BALH demonstrated superior adsorption capacities for both cationic methylene blue and anionic methyl orange (MO) compared to traditional kraft lignin. The adsorption capacity for MO reached approximately 900–930 mg/g, following a pseudo-second-order kinetic model and the Langmuir isotherm model, indicating chemisorption and homogeneous monolayer adsorption. Thermodynamic studies revealed the spontaneous endothermic nature of the adsorption process. Remarkably, BALH maintained a high removal efficiency even after 10 adsorption and desorption cycles, and continuous adsorption experiments confirmed its practical effectiveness. Because of its ultrahigh dye-removal capacity, structural stability, recyclability, and ease of separation, BALH is a promising candidate for scalable wastewater treatment solutions. The study of lignin modification may also offer innovative systems for modifying and cross-linking lignin. [ABSTRACT FROM AUTHOR]

In this study, modified aminated lignin derivatives (MALDs) with high phenolic hydroxyl group contents were prepared via a facile reaction between aminated lignin and 3,4-dihydroxyhydrocinnamic acid. Elemental analysis (EA), 1H- and 31P NMR spectroscopy, zeta potential, Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and X-ray photoelectron spectroscopy (XPS) were hired to characterize the impact of the reaction conditions on the specific structural properties and phenolic hydroxyl group level of the MALDs. The reaction mechanism for the MALDs preparation has been proposed based on this analysis. With a 2,2-diphenyl-1-picrylhydrazyl (DPPH) elimination rate of 89.90% recorded at a concentration of 0.5 mg/L, the testing results demonstrated that MALDs with a high phenolic hydroxyl content (2.71 mmol/g) display excellent antioxidant activity. Furthermore, MALDs exhibited an ultrahigh adsorption capacity for hexavalent chromium ion (Cr(VI)) removal (161.5 mg/g) because of enough active sites available. The use of lignin in the wastewater treatment field is now more feasible as a result of this work. [Display omitted] • Modified aminated lignin derivatives (MALDs) enriched in Ph-OH were prepared. • A rapid, efficient and facile method was developed for the preparation of MALDs. • The antioxidant activity of MALDs is significantly improved. • MALDs exhibited an ultrahigh adsorption capacity for Cr(VI) removal (161.5 mg/g). • Phenolic hydroxyl modification is an effective method for utilization of lignin. [ABSTRACT FROM AUTHOR]

The introduction of active groups from biomass is currently the most promising alternative method for increasing the adsorption effect of dyes. In this study, modified aminated lignin (MAL) rich in phenolic hydroxyl and amine groups was prepared by amination and catalytic grafting. The factors influencing the modification conditions of the content of amine and phenolic hydroxyl groups were explored. Chemical structural analysis results confirmed that MAL was successfully prepared using a two-step method. The content of phenolic hydroxyl groups in MAL significantly increased to 1.46 mmol/g. MAL/sodium carboxymethylcellulose (NaCMC) gel microspheres (MCGM) with enhanced methylene blue (MB) adsorption capacity owing to the formation of a composite with MAL were synthesized by a sol-gel process followed by freeze-drying and using multivalent cations Al3+ as cross-linking agents. In addition, the effects of the MAL to NaCMC mass ratio, time, concentration, and pH on the adsorption of MB were explored. Benefiting from a sufficient number of active sites, MCGM exhibited an ultrahigh adsorption capacity for MB removal, and the maximum adsorption capacity was 118.30 mg/g. These results demonstrated the potential of MCGM for wastewater treatment applications. [Display omitted] • Modified aminated lignin (MAL) with amine and phenolic groups was successfully prepared. • MAL/NaCMC gel microspheres (MCGM) were prepared by a sol-gel process. • MAL endows MCGM with good physical and swelling properties. • MCGM exhibited an enhanced adsorption capacity for methylene blue. [ABSTRACT FROM AUTHOR]

Multifunctional polymers derived from renewable organic substances have received significant attention. In this work, the Diels–Alder "click" reaction was used to synthesize a renewable copolymer with the mechanical strength of cellulose nanocrystals (CNCs) and the natural antioxidant activity of lignin. Chemical structural analysis and molecular weight results confirmed that lignin was successfully attached to the CNCs. Phenolic hydroxyl groups were introduced into CNCs, resulting in good antioxidant activity with an IC 50 value of 1.49 mg/mL, although a slight decrease in the crystallinity index and thermal properties was observed. Additionally, carboxymethyl cellulose (CMC) films containing lignin-modified CNCs were prepared by solution casting. The lignin-modified CNCs endowed film with antioxidant activity and also contributed to increasing the tensile strength by 70%. This indicated that the lignin-modified CNCs with good antioxidant activities and mechanical strength have promising applications in multifunctional materials. [Display omitted] • Lignin-modified CNCs were synthesized via Diels–Alder reaction. • Lignin-modified CNCs had significant antioxidant activity. • CMC film containing lignin-modified CNCs exhibited antioxidant activity. • CMC film containing lignin-modified CNCs exhibited improved tensile strength. [ABSTRACT FROM AUTHOR]