Production and Application of Lignosulfonates and Sulfonated Lignin

Lignin self-assembly phenomena and valorization strategies for pulping, biorefining, and materials development: Part 2. Factors affecting the specificity of lignin self-assembly for industrial applications

This review considers a profoundly underutilized resource, technical lignin, and its potential for large scale upgrading for higher-valued industrial usage by means of self-assembly processes. Molecular interactions that can be used to guide lignin self-assembly are systematically explored, categorizing them into physicochemical interaction-driven assembly and external stimuli or template-driven assembly. Published findings are examined to reveal molecular mechanisms governing lignin aggregation into lignin nanoparticles (LNPs), films, and interfacial behavior in Pickering emulsions that have potential to be used industrially. Recent advancements in experimental techniques are explored to provide deeper insights into lignin's self-assembly processes. Hydrophobic effects, π-π stacking, hydrogen bonding, electrostatic layering, polyelectrolyte complex formation, chain entanglement, and covalent cross-linking are critically assessed as potential means to control the self-assembly of lignin and systems involving lignin. Additionally, external factors, such as chemical dehydration, solvent-mediated interactions, and external fields are examined related to their role in templating lignin assembly. Based on a comprehensive review of the literature, hydrophobic interactions are predominant in lignin aggregation, with hydrophobicity degrees varying significantly across lignin samples. Interfacial rheology studies demonstrate that lignosulfonate exhibits maximum storage moduli at oil-water interfaces, significantly enhancing emulsion stability. Additionally, modified lignins via esterification contribute larger lifetimes of water-in-oil emulsions stability under varying salinity and oil types. The integration of molecular modeling with experimental characterization techniques can further optimize lignin-based materials for multiple applications, such as drug delivery, catalysis, advanced pesticide delivery systems, bioplastics, 3D printing, and emulsification, among many others. Although there are existing technical and economic assessments (TEA) and life cycle assessments (LCA) involving lignin self-assembly that point to promising prospects, there is a need for more comprehensive TEA and LCA work to clear the way for the needed industrial innovations in this field.

Mussel-inspired robust and waterproof soybean protein adhesives enhanced with phenolated lignosulfonate for wood bonding

Plant protein-based adhesives are favored for their cost-effectiveness and environmental friendliness. However, the low reactivity of plant protein and inherent water sensitivity of its adhesive significantly limits their scalability and broader application. Drawing inspiration from mussels, we developed a robust and waterproof bio-based adhesive reinforcing soybean protein (SP) with lignosulfonate. Specifically, the lignosulfonate was modified with phenol and epoxidated to synthesize phenolated lignin epoxy resin (PLEP), which was then added into SP matrix. The resulting adhesive demonstrated excellent bonding performance, with a dry shear strength of 3.59 MPa and a wet shear strength of 2.07 MPa. Finite Element Method (FEM) simulation confirmed a decreased stress concentration due to energy dissipation for the SP/PLEP. Furthermore, the adhesive exhibited an 81.22 % residual rate after water immersion. The adhesion strength was enhanced due to the π-π/cation-π interactions, hydrogen bonds, metal coordination of calcium ions, and covalent bonds formed by amino groups in proteins. Molecular dynamics (MD) analysis verified the enhancement of intermolecular interaction after phenolic modification. Life cycle assessment (LCA) revealed that the environmental impact of SP/PLEP adhesive was lower than that of urea-formaldehyde resin. This study presents a soybean-based adhesive inspired by mussel, offering a straightforward strategy for developing biomimetic adhesives.

Synthetic Lignin Oligomers: Analytical Techniques, Challenges, and Opportunities

Lignin is the second most abundant renewable material after cellulose. However, its economic use is currently relegated to low-value energy production. This biomaterial holds great potential as a source of renewable biofuels, bio-based chemicals, advanced materials, and integrated biorefineries. Fractionation and depolymerization methods yield liquid repositories of promising aromatic monomers and lignin oligomers (LO) that retain many of the structural components found in the native material. However, analyzing this complex mixture is challenging due to the wide range of molecular sizes and heterogeneous chemical structure, which makes their structural elucidation a critical obstacle - unlocking the full potential of lignin hinges upon developing appropriate standards and analytical methods to address existing knowledge gaps. This review provides a comprehensive examination of current analytical techniques for elucidating the chemical structure of lignin oligomers, exploring synthesis methods, molecular structures, and their advantages and limitations. Built upon these findings, opportunities for synergy between synthetic oligomers and lignin utilization can be revealed, such as bioactive compound production and biorefinery integration. Moreover, we underscore the need for standardized analytical methods to facilitate the design of lignin oligomer standards and their diverse applications.

Valorization of lignin biowaste into Schiff base copper(II) complex as a magnetically reusable electrocatalyst for hydrogen evolution reaction

This work describes a cost-effective and sustainable copper(II) complex as an electrocatalyst for the hydrogen-evolution reaction (HER) under alkaline and acid conditions. A magnetic lignin-supported tetrazole Schiff base copper(II) complex was incorporated into a carbon paste electrode (MLS@SchTet-Cu(II)/CPE) by a surface modification and cross-linking method. The catalytic HER of the MLS@SchTet-Cu(II)/CPE electrodes was analyzed by electrochemical techniques, including linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), chronopotentiometry (CP), and cyclic voltammetry (CV). The effects of solution pH and complex amount in the paste electrode on HER performance were evaluated. The results demonstrated that the MLS@SchTet-Cu(II) nanocomposite exhibits good electrocatalytic activity in both acidic and basic media. In particular, in 0.5 M H2SO4, the modified CPE electrode with 2.5 % MLS@SchTet-Cu(II) demonstrated an overpotential of 581 mV at 10 mA cm-2 (η10) and a Tafel slope of 258 mV dec-1, surpassing the performance of both the bare and other modified CPEs. These findings highlight the potential of MLS@SchTet-Cu(II) as a promising candidate for sustainable HER catalysis.

Lignin-based metal chelate fertilizers: preparation, properties and applications

Lignin, as a renewable natural polymer, is recognized as a promising metal chelating agent due to its reactive functional groups capable of chelating metal ions. However, the relatively limited number of reactive functional groups in lignin restricts its chelating capacity to a certain extent and hence limits its application as a metal chelating fertilizer. This review focuses on various lignin modification methods, including sulfonation, sulfomethylation, amination, oxidation, carboxymethylation, demethylation, and phenolization, which can increase the number of functional groups available for metal chelation in lignin. Furthermore, the methods for preparing lignin-based metal chelate fertilizers utilizing modified lignin with necessary classifications and summaries were systematically introduced. The application effects of lignin-based metal chelate fertilizers in plant cultivation are discussed, with particular emphasis on their role in enhancing plant nutrient absorption, improving soil fertility, alleviating plant stress, and reducing the uptake of heavy metals by crops. Overall, the aim of this review is to provide theoretical support and practical guidance for the further application of lignin in the agricultural field as an indispensable component in metal chelate fertilizers.

Quantitative Characterization of Modified Lignin Using Solid-State 13C NMR Spectroscopy

Solid-state 13C nuclear magnetic resonance (NMR) spectroscopy with magic angle spinning (MAS) and direct polarization (DP) techniques is a valuable tool for quantitative and reliable characterization of lignin derivatives, specifically for determining these chemical structures and the degree of substitution upon chemical modification. In this study, the DPMAS 13C NMR spectroscopy was used in a quantitative study of the esterifying reaction in lignin derivatives, which allowed the whole lignin structure to be determined. This quantitative evaluation system using DPMAS 13C NMR spectroscopy can be widely utilized for lignin characterization without a specific chemical treatment or decomposition of lignin.

Lignin-Based Separators for Lithium-Ion Batteries via a Dry Fibrillation Method

Separators are critical components in lithium-ion batteries (LIBs), preventing internal short circuits, mitigating thermal runaway, and influencing rate capability and cycling performance. However, current polyolefin separators suffer from limitations, such as high thermal shrinkage, relatively poor wettability, and inadequate long-term stability, impacting safety and cycle life in critical applications like electric vehicles. Here, a single-layer lignin-based ultrathin separator (as thin as 15 µm) with exceptional intrinsic thermal stability and cycling performance is demonstrated. The separator is fabricated using lignosulfonate, a natural polymer derived as a byproduct of chemical pulping and biorefinery processes. By employing a dry fibrillation method, the process achieves low energy consumption and a 100% raw material conversion rate, highlighting its scalability and sustainability. Interfacial studies reveal the improved cycling performance in both graphite||NMC811 and Si-Gr||NMC811 cells is attributed to the abundant sulfonate functional groups in lignosulfonates, which promote the formation of a sulfur-rich cathode/solid electrolyte interphases (CEI/SEI) with low resistance in both the cathode and anode. The high thermal stability, manufacturing feasibility, battery performance, and low cost of such lignin-based separators offer new inspiration for developing next-generation, single-layer functional separators tailored for high-performance LIBs.

Lignin-induced eutectogel electrolytes enabling wide-temperature tolerance and high energy density zinc-ion hybrid supercapacitors

Zinc-ion hybrid supercapacitors (ZHS) have demonstrated tremendous potential in the field of energy storage for wearable electronics, as they combine the higher energy density of zinc-ion batteries with the superior power density of supercapacitors. However, conventional solid electrolytes with low conductivity, extreme environments intolerance, safety risks, and a time- and energy-consuming preparation process, which hinders the applications of ZHS. Herein, a self-catalytic system (SLSFe3+) basing on sulfonated lignin (SLS) was used to rapidly (∼60 s) fabricate polyacrylamide-SLS hydrogels (PLH). Zinc perchlorate (Zn(ClO4)2) was used as hydrogen bond acceptor, ethylene glycol (EG) as hydrogen bond donor, and water as diluent to lower viscosity to create a metal salt-based ternary hydrated eutectic solvent (DES). PLH were immersed in the DES to obtain eutectogels. The prepared eutectogels displayed enhancing properties of mechanical strength (∼2160 % elongation), ionic conductivity (45.3 mS cm-1), antifreeze/non-drying and flame-retardant (a LOI value of 47.3). The ZHS assembled with the eutectogel electrolyte exhibited a high energy density of 216.94 Wh kg-1 at a high-power density of 712 W kg-1. Meanwhile, the ZHS had long cycle stability at -20 °C, with 70 % capacity retention after 10,000 long cycles. This study provides an effective strategy for the preparation of full-performance eutectogel electrolytes.

Biowaste ligninsulfonate functionalized cathode of lithium-sulfur battery for immobilization and catalyzation of polysulfides

Lithium‑sulfur batteries (LSBs) have been appealing an increasing attention in last ten years with the overwhelming advantages of greatly higher theoretical energy density and specific capacity in comparison with traditional Li-ion batteries (LIBs). However, the commercial application of LSBs still confronts some intractable challenges, of which the shuttle effect and sluggish redox kinetics are reckoned as the most serious obstacles. Incorporation of polar sulfonate groups into cathode has been believed as an effective avenue to immobilize polysulfides and thus enables to alleviate the shuttle effect. Moreover, those grafted sulfonate groups create some more Li+ high-speed pathways and meanwhile catalyze the redox conversion of polysulfides, which as a consequence greatly expedites the redox kinetics of LSB. To circumvent the hazardous reagents and complicated procedures for the introduction of sulfonate groups, herein the biomacromolecule ligninsulfonate (LS), a high-yield biowaste from the classical sulfite pulping industry, is employed to host elemental S followed by blending with conductive carbon nanotubes (CNTs). After replacing by Li+ ions, the as-prepared S@LiLS/CNTs cathode exhibits high specific capacity (1265 mAh g-1 at 0.2C), superior rate capability (629 mAh g-1 at 5C), and stable cyclability (70 % capacity retention after 1000 cycles). This work paves the avenue of exploiting waste biological macromolecules in high-performance electrodes of advanced energy storage systems.

Effect of hydrophobically-modified sulfonated lignin on thermal stability of disperse dye paste

This study aims to develop a lignin-based dispersant with excellent high-temperature dispersion properties by introducing cyclohexyl and phenyl hydrophobic groups into sulfomethylated lignin (SAL) molecules through a grafting modification strategy, thereby addressing the limitations of traditional disperse dye pastes in terms of grinding efficiency and thermal stability. The results show that graft-modified lignin dispersants outperform both SAL and the commercial dispersant Reax-85A. They not only improve the grinding efficiency of disperse dye pastes but also markedly enhance their thermal stability. The particle size of disperse dye paste significantly decreased from greater than 5 μm to 1 μm. The lignin dispersant containing cyclohexyl and phenyl groups significantly enhanced the hydrophobic van der Waals adsorption forces toward disperse dyes. Under high-temperature conditions, the prepared disperse dye pastes maintained excellent diffusion performance and thermal stability. QCM-D studies revealed that the adsorption capacity |ΔF| of hydrophobically-modified SAL on disperse dyes was significantly enhanced compared to that of SAL and Reax-85A, and it exhibited strong adsorption stability with minimal desorption, demonstrating robust adhesion to disperse dyes. Furthermore, the adsorption quantity of phenyl-modified SAL on disperse dyes was greater than that of cyclohexyl-modified SAL.

Bio-Based Stabilization of Natural Soil for Rammed Earth Construction: A Review on Mechanical and Water Durability Performance

Rammed earth (RE), despite being an ancient method of construction, has smoothly integrated into contemporary civil engineering due to its compatibility with current sustainability requirements for housing structures. However, typical RE needs some improvements to fully realize its potential as both a structurally effective and environmentally friendly building technique. As a result, multiple bio-inspired enhancement methods have been suggested to substitute traditional cement or lime stabilizers. This review examines the various efforts made in the past decade to biologically stabilize natural soil for the construction of RE. It provides a brief overview of the different bio-based materials utilized in this area but primarily concentrates on their effects on the mechanical strength and water durability of RE structures. The review also addresses current obstacles that prevent the widespread industrial adoption of this valuable earth-building method and identifies potential directions for future research. Overall, the available literature on the mechanical performance and durability of bio-based rammed earth (BRE) shows encouraging outcomes. Nonetheless, various issues, such as the absence of thorough data on the discussed topics, issues related to the inherent properties of soil and biomaterials, and doubts regarding the reliability of durability evaluation methods, have been identified as factors that could lead to a lack of confidence among RE practitioners in adopting bio-based treatments. This study will provide a solid foundation for future researchers aiming to advance BRE technology, thus enhancing sustainability within the construction sector.

Lignin and Nanolignin: Next-Generation Sustainable Materials for Water Treatment

Water scarcity, contamination, and lack of sanitation are global issues that require innovations in chemistry, engineering, and materials science. To tackle the challenge of providing high-quality drinking water for a growing population, we need to develop high-performance and multifunctional materials to treat water on both small and large scales. As modern society and science prioritize more sustainable engineering practices, water treatment processes will need to use materials produced from sustainable resources via green chemical routes, combining multiple advanced properties such as high surface area and great affinity for contaminants. Lignin, one of the major components of plants and an abundant byproduct of the cellulose and bioethanol industries, offers a cost-effective and scalable platform for developing such materials, with a wide range of physicochemical properties that can be tailored to improve their performance for target water treatment applications. This review aims to bridge the current gap in the literature by exploring the use of lignin, both as solid bulk or solubilized macromolecules and nanolignin as multifunctional (nano)materials for sustainable water treatment processes. We address the application of lignin-based macro-, micro-, and nanostructured materials in adsorption, catalysis, flocculation, membrane filtration processes, and antimicrobial coatings and composites. Throughout the exploration of recent progress and trends in this field, we emphasize the importance of integrating principles of green chemistry and materials sustainability to advance sustainable water treatment technologies.

Infrared Free-Electron Laser: A Versatile Molecular Cutter for Analyzing Solid-State Biomacromolecules

Free-electron lasers that oscillate in the infrared (IR) range of 1000 (10 μm) to 4000 cm-1 (2.5 μm) were applied to irradiate solid-phase polysaccharides and aromatic biomacromolecules. Synchrotron radiation IR microscopy (SR-IRM) and electrospray ionization mass spectroscopy (ESI-MS) analyses showed that N-acetyl glucosamine was isolated from the powdered exoskeleton of crayfish by irradiation at 1020 cm-1 (9.8 μm), resonating with the C-O stretching mode (νC-O). Irradiation at 3448 cm-1 (2.9 μm), which is resonant with the O-H stretching vibration (νO-H) of sulfonated lignin, dissociates the aggregate state and releases coniferyl aldehyde substituted with sulfinate, as shown by scanning electron microscopy, terahertz-coherent edge radiation spectroscopy, SR-IRM, and ESI-MS. These vibrational excitation reactions proceed at room temperature in the absence of solvent. Current and previous studies have demonstrated that intense IR lasers can be used as versatile tools for unveiling the internal structures of persistent biomacromolecules.

High-response humidity sensing with graphene oxide/lignosulfonate and laser-induced graphene for respiratory health

Most current commercial humidity sensors rely on precious metals and chemicals. In this study, alkali lignin produced in the paper industry was utilized to form a film with hydroxyethyl cellulose to generate laser-induced graphene (LIG) as an electrode material for a sensor by the laser-induction technique. LIG exhibits excellent conductivity, and the experimental results demonstrate that its resistivity can be adjusted by laser power without the necessity for additional conductive materials. A solution comprising a blend of graphene oxide and sodium lignosulfonate was introduced to the LIG surface in a dropwise manner, thereby establishing a sensing surface. This process resulted in the introduction of hydrophilic groups, including carboxyl, phenolic hydroxyl, and sulfonic acid. The integration of these hydrophilic groups enhanced the surface's sensitivity to humidity, thereby facilitating the precise capture of alterations in ambient air humidity. The humidity sensor, which employs alkali lignin and lignin laser-induced graphene as electrodes and graphene oxide (GO) as the humidity-sensitive layer, exhibits an exceptionally high degree of sensitivity to humidity. The response reached 42.74 (R RH/R 0) at 80% relative humidity and 133.96 (R RH/R 0) at 90% humidity with a sensitivity of 147.73%/% RH. Moreover, the sensor displays an impressively brief recovery period, which remains unaltered even after multiple cycles. Additionally, the humidity sensor exhibits excellent stability for a period of up to 30 days. This study has successfully developed a simple and efficient method for preparing graphene, and has produced a flexible resistive sensor with high sensitivity, repeatability, and stability, thereby opening up new avenues for the high-value utilisation of lignin.

Chemistry of lignin and condensed tannins as aromatic biopolymers

Aromatic biopolymers are the second largest group of biopolymers after polysaccharides. Depolymerization of aromatic biopolymers, as cheap and renewable substitutes for fossil-based resources, has been used in the preparation of biofuels, and a range of aromatic and aliphatic small molecules. Additionally, these polymers exhibit a robust UV-shielding function due to the high content of aromatic groups. Meanwhile, the abundance of phenolic groups in their structures gives these compounds outstanding antioxidant capabilities, making them well-suited for a diverse array of anti-UV and medical applications. Nevertheless, these biopolymers possess inherent drawbacks in their pristine states, such as rigid structure, low solubility, and lack of desired functionalities, which hinder their complete exploitation across diverse sectors. Thus, the modification and functionalization of aromatic biopolymers are essential to provide them with specific functionalities and features needed for particular applications. Aromatic biopolymers include lignins, tannins, melanins, and humic acids. The objective of this review is to offer a thorough reference for assessing the chemistry and functionalization of lignins and condensed tannins. Lignins represent the largest and most prominent category of aromatic biopolymers, typically distinguishable as either softwood-derived or hardwood-derived lignins. Besides, condensed tannins are the most investigated group of the tannin family. The electron-rich aromatic rings, aliphatic hydroxyl groups, and phenolic groups are the main functional groups in the structure of lignins and condensed tannins. Methoxy groups are also abundant in lignins. Each group displays varying chemical reactivity within these biopolymers. Therefore, the selective and specific functionalization of lignins and condensed tannins can be achieved by understanding the chemistry behavior of these functional groups. Targeted applications include biomedicine, monomers and surface active agents for sustainable plastics.

Preparation of quaternary ammonium lignosulfonate modified UV resistant polyurethane and its application in leather dyeing

Applying cationic waterborne polyurethane (CWPU) in the leather color-fixing process can improve the dyeing rate and enhance color fastness. However, under prolonged exposure to sunlight, CWPU will age and degrade and the leather will fade in color, become stiff and crack easily. In this study, an Ultraviolet absorber was introduced into cationic waterborne polyurethane (UVCWPU) and quaternary ammonium Lignosulfonate (QLS) was prepared by quaternization. Quaternary ammonium Lignosulfonate/UV-resistant waterborne polyurethane (QLS/UVCWPU) composite was prepared by the blending method. A one-way experiment was carried out to investigate the effect of the additional amount of quaternary ammonium reagent on the degree of modification of QLS, and the results showed that when the ratio of 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTMAC) to LS was 7:1, the isoelectric point of the prepared QLS reached 6.65, and the content of N was 4.32 % so that the quaternary ammonium lignosulfonate modification was successful. QLS/UVCWPU was used to solidify the leather at pH 4.0 and a dosage of 4 %. The dye absorption rate of the leather increased to 97.3 %, the K/S value of the dyed gray leather reached 28.51, the color fastness to dry rubbing was improved to grade 5, and the color fastness to wet rubbing was up to grade 3 and enhancing the color fastness to sunlight, slowing down the effect of ultraviolet aging, and improving the antimicrobial properties of the leather.

Lignin-based nano-mimetic enzymes: A promising approach for wastewater remediation

Lignin-based nano-mimetic enzymes have emerged as a promising approach for wastewater remediation, addressing the limitations of conventional treatment methods. This review article explores the potential of lignin, a renewable biomaterial, in developing these novel enzyme-inspired systems. The introduction highlights the rising pollution levels, stricter environmental regulations, and the need for innovative wastewater treatment technologies. The advantages of enzyme-based systems, such as high specificity, efficiency, and environmental friendliness, are discussed. The article then delves into the structure, extraction, and modification of lignin, as well as its applications in wastewater treatment. The concept of nano-mimetic enzymes and their advantages over traditional enzymes are presented, along with strategies for developing lignin-based nano-mimetic enzymes. The review examines the pollutant removal performance of these systems, covering the removal of organic and inorganic pollutants and the underlying mechanisms involved. Operational parameters, optimization strategies, and characterization techniques are also covered. The practical applications, challenges, and future research directions are discussed, emphasizing the significance, advantages, limitations, and potential benefits of lignin-based nano-mimetic enzymes for wastewater remediation. This comprehensive review highlights the promising potential of this innovative approach in addressing the pressing environmental issues related to wastewater treatment.

Lignosulfonate-based deflocculant and its derivatives for water-based drilling mud: A review

Chromium-based lignosulfonate (CrLS) deflocculants that are commonly used in water-based drilling muds (WBDMs) to deflocculate bentonites under high temperature (HT), high-pressure (HP), and high-salinity (HS) oil well drilling conditions have been found to contain heavy metals such as chromium, which is toxic and degrades rapidly. However, different ways of addressing this issue have been proffered, including the use of natural polymers such as starch, cellulose, or anionic inorganic agents such as sodium polyphosphates with little or no impact. Other lignosulfonate (LS)-based deflocculants, like sodium-based LS and bio-based LS, have shown a number of benefits, such as being better for the environment, more soluble and evenly distributed in WBDMs, more resistant to salt contamination, easily biodegradable, safe, and able to go through different chemical changes. This is due to its abundant functional groups, which make it a suitable alternative to chrome-based deflocculants. This review discusses LS-based deflocculants as possible additives to WBDMs in comparison with some non-LS-based deflocculants under HTHP and HS conditions. This could address the need for safer alternatives to natural polymers or inorganic agents. Based on recently reviewed studies, the advantages, uses, research obstacles, green synthesis, and potential of incorporating nanotechnology-based modification for LS-based deflocculants improvement in WBDMs under HTHP and HS drilling conditions are discussed.

A Robust Lignin-Derived Moisture-Enabled Electric Generator with Sustained and Scalable Power Output

Leveraging ubiquitous moisture and abundant biomass in nature to convert chemical energy into electrical energy holds great promise for meeting energy demands. Herein, we report a simple, green, low-cost, and high-performance lignin-derived moisture-enabled electric generator (LMEG). An LMEG device with an area of 0.25 cm2 can give a stable open-circuit voltage of 1.26 V, a high short-circuit current density of 439.36 μA cm-2, and a maximum power density of up to 32.73 μW cm-2. Moreover, the LMEG exhibits continuous electrical output for at least 2 months, demonstrates high tolerance to a wide range of working environments and mechanical deformations, and is recyclable. Besides, a near-linear increase in electric production can be achieved by integrating LMEG devices in series or parallel, significantly with a current of 1.45 mA obtained by connecting only 18 LMEG units in parallel. The integrated LMEG can successfully drive various electronic products, including LED arrays, electronic watches, and hygrometers, highlighting its potential in self-powered systems and sensing applications.

Green Polymer Derived Multifunctional Layer Achieving Oriented Diffusion and Controllable Deposition of Zn2+ for Ultra-Durable Zinc-Ion Hybrid Supercapacitors

Rampant dendrite growth and severe parasitic reactions at the electrode/electrolyte interface significantly limit the cycle life of aqueous zinc ion hybrid supercapacitors (ZHSCs). In this study, sodium lignosulfonate (SLS) as one green polymer was introduced into ZnSO4 electrolyte to construct a multifunctional layer on the surface of Zn plates. Experimental analyses and theoretical calculations show that the presence of the SLS layer, rich in oxygen-containing functional groups (-SO3-), can not only modulate the structure of the electric double layer (EDL) to suppress interfacial side reactions caused by free H2O and SO42-, but also promote (101)-oriented deposition by selectively controlling the deposition behavior of Zn2+ through specific adsorption on different crystalline surfaces. The optimized electrolyte allows stable Zn//Zn symmetric cells to achieve a cumulative plating capacity exceeding 4 Ah cm-2 at a high areal capacity of 5 mAh cm-2, and stable cycling for more than 1000 cycles with an excellent average Coulombic efficiency of 99.34% in Zn//Cu asymmetric cells. The Zn//AC ZHSC exhibits ultralong cycling stability of over 40,000 cycles in the optimized electrolyte, with a capacity decay rate as low as 0.000285% per cycle.

Advancements in Lignin Valorization for Energy Storage Applications: Sustainable Technologies for Lignin Extraction and Hydrothermal Carbonization

The conversion of industrial waste lignin into sustainable carbon materials is an essential step towards reducing dependency on fossil fuels and mitigating environmental impacts. This review explores various aspects of lignin utilization, with particular focus on the extraction of lignin and the application of lignin-derived carbon materials in energy storge applications. The review explores advanced chemical methods to improve the efficiency of biomass conversion, detailing emerging technologies for lignin extraction from various biomasses using innovative solvents and techniques, such as Ionic Liquids and Deep Eutectic Solvents (DESs). Additionally, it discusses the parameters that impact the hydrothermal carbonization (HTC) process. The produced hydrochar shows potential for use as optimized precursors for energy storage applications. This review also considers the implications of these technologies for environmental sustainability and the circular economy, suggesting future research directions to enhance and scale these processes for global impact. This comprehensive analysis highlights the critical role of advanced biomass conversion technologies in achieving sustainability and outlines pathways for future lignin-based carbon materials innovations.

Solvent-Free Catalytic Hydrotreatment of Lignin to Biobased Aromatics: Current Trends, Industrial Approach, and Future Perspectives

Lignin is the only naturally occurring, renewable biopolymer and an alternative for the production of six-membered aromatic chemicals. The utilization of lignin can increase the additional revenue of biorefineries and reduce the dependence on crude oil for the production of aromatic chemicals. Therefore, the development of technologies for the production of valuable chemicals from lignin waste in biorefineries is of great importance. Catalytic hydrotreatment of lignin is considered one of the most promising technologies for the production of biobased aromatic chemicals and fuels. Among the various hydrotreatment routes, the solvent-free hydrotreatment approach is advantageous because this process reduces production costs and is similar to petroleum refinery processes such as cracking and heteroatom removal. This review addresses recent developments in solvent-free catalytic hydrotreatment of various lignins such as sulfur-containing, sulfur-free, and pyrolytic lignins to produce low oxygen-containing aromatics such as alkylphenolics in batch, semicontinuous, and continuous reactors. Special emphasis is given to the various noble and non-noble metal catalysts, the best route between single and two-stage processing, key factors in solvent-free depolymerization of lignin, techno-economic evaluation, crude oil vs lignin oil refining, challenges and future prospects, etc.

A Systematic Study of the Structural Properties of Technical Lignins

Technical lignins are globally available and a sustainable feedstock. The unique properties of technical lignins suggest that these materials should have several industrial applications. The main proposal of this study is to evaluate the relationship between the structure and properties of two technical lignins. Morphological, chemical, physical, and thermal properties of sodium lignosulfonate (LGNa) and magnesium lignosulfonate (LGMg) were investigated. The results showed that a higher formation of intramolecular hydrogen bonds may occur in lignins with a higher content of phenolic hydroxyl groups, such as LGMg. As a result, an increase in the energy of hydrogen bonds in the lignosulfonate structure was observed, without significant change in the hydrogen bond distances. In addition, higher content of phenolic hydroxyl groups might also reduce lignosulfonates thermal stability. The combustion index value was three times higher for LGMg than for LGNa. The characterization study also revealed that phenolic hydroxyl groups influence the main properties of technical lignins and can be a determining factor when these lignosulfonates are used in industrial applications.

Optimizing soil remediation with multi-functional L-PH hydrogel: Enhancing water retention and heavy metal stabilization in farmland soil

Agricultural soils face severe challenges, including water scarcity and heavy metal contamination. Optimizing soil remediation efficiency while minimizing inputs is essential. This study assessed the water retention and heavy metal adsorption properties of L-PH hydrogel through aqueous experiments. Fourier Transform Infrared (FTIR) and X-ray Photoelectron Spectroscopy (XPS) elucidated the adsorption mechanisms. The results showed that L-PH hydrogel exhibited high water absorption efficiency, with Zn2+ removed via electrostatic interactions and cation exchange, and Cd2+ and Cu2+ adsorbed through coordination complexation. Soil experiments tested water retention and heavy metal leaching under various application methods (M1 = 0-10 cm mixed, M2 = 10-20 cm mixed, T1 = 5-10 cm layered, T2 = 10-15 cm layered) and rates (NL = 0 %, L1 = 0.1 %, L2 = 0.2 %, L3 = 0.5 %). L-PH reduced water infiltration, enhanced soil water retention, and decreased heavy metal mobility across all treatments. The highest water retention was observed in the M1 method. Under M1L1, cumulative leaching of Cd2+, Cu2+, and Zn2+ decreased by 68.84 %, 33.44 %, and 83.60 %, respectively. Two-way ANOVA revealed that application rate had a greater effect on leaching than the method. FTIR and XRD analyses showed that at low concentrations (L1, L2), L-PH formed coordination bonds with Cd2+ and Cu2+, creating Cd(HCOO)2·2(NH2)2CO and Cu(HCOO)(OH) in the soil. Zn2+ was stabilized through adsorption and precipitation, forming Zn(OH)2, thereby reducing leaching. Higher concentrations of L-PH may have further interacted with Zn, leading to dissolution and adsorption/precipitation processes. Redundancy analysis (RDA) analysis suggests that an increase in organic carbon and moisture content in soil aggregates larger than 2 mm, along with a decrease in bioavailable heavy metals, may enhance heavy metal stabilization, reducing their movement and leaching. This study offers valuable insights into addressing the twin challenges of water scarcity and heavy metal pollution.

Environmental concerns on water-soluble and biodegradable plastics and their applications - A review

Water-soluble polymers are materials rapidly growing in volume and in number of materials and applications. Examples include synthetic plastics such as polyacrylamide, polyacrylic acid, polyethylene glycol, polyethylene oxide and polyvinyl alcohol, with applications ranging from cosmetics and paints to water purification, pharmaceutics and food packaging. Despite their abundance, their environmental concerns (e.g., bioaccumulation, toxicity, and persistence) are still not sufficiently assessed, especially since water soluble plastics are often not biodegradable, due to their chemical structure. This review aims to overview the most important water-soluble and biodegradable polymers, their applications, and their environmental impact. Degradation products from water-insoluble polymers designed for biodegradation can also be water soluble. Most water-soluble plastics are not immediately harmful for humans and the environment, but the degradation products are sometimes more hazardous, e.g. for polyacrylamide. An increased use of water-soluble plastics could also introduce unanticipated environmental hazards. Therefore, excessive use of water-soluble plastics in applications where they can enter the environment should be discouraged. Often the plastics can be omitted or replaced by natural polymers with lower risks. It is recommended to include non-biodegradable water-soluble plastics in regulations for microplastics, to make risk assessments for different water-soluble plastics and to develop labels for flushable materials.

Green preparation of reusable Pd@magnetic lignosulfonate nanocomposite for hydrogen evolution reaction in all pHs

In this study, palladium nanoparticles (Pd NPs) were successfully synthesized and supported on a cost-effective, eco-friendly magnetic lignosulfonate matrix using Hibiscus Rosasinensis L. leaf extract as a natural reducing and stabilizing agent (Pd@Fe₃O₄-lignosulfonate). The magnetic lignosulfonate prevented the aggregation of Pd NPs, enhanced the active surface area, and improved the hydrophilicity of the modified carbon paste electrode (CPE), thus boosting hydrogen production efficiency. The Pd@Fe₃O₄-lignosulfonate was incorporated into the CPE at different weight percentages (1.5, 2.5, 5, 10, and 15 %), and employed as an efficient electrocatalyst for the hydrogen evolution reaction (HER) across all pH conditions (0.5 M H₂SO₄, 1 M NaOH, and phosphate buffer at pH 7). Electrochemical techniques such as linear sweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), chronoamperometry (CA), and chronopotentiometry (CP) were employed to assess the catalyst's performance. Optimal hydrogen generation was achieved at 10 wt% Pd@Fe₃O₄-lignosulfonate/CPE, yielding an overpotential of -239 mV (vs. RHE) at a current density of 10 mA. cm-2 and a Tafel slope of -62 mV. dec-1 under acidic conditions. This work positions the low-loaded Pd NPs on magnetic lignosulfonate as a viable alternative to traditional noble metal catalysts, contributing to advancements in green chemistry and sustainable energy solutions.

Real-Time Model Predictive Control of Lignin Properties Using an Accelerated kMC Framework with Artificial Neural Networks

While lignin has garnered significant research interest for its abundance and versatility, its complicated structure poses a challenge to understanding its underlying reaction kinetics and optimizing various lignin characteristics. In this regard, mathematical models, especially the multiscale kinetic Monte Carlo (kMC) method, have been devised to offer a precise analysis of fractionation kinetics and lignin properties. The kMC model effectively handles the simulation of all particles within the system by calculating reaction rates between species and generating a rate-based probability distribution. Then, it selects a reaction to execute based on this distribution. However, due to the vast number of lignin polymers involved in the reactions, the rate calculation step becomes a computational bottleneck, limiting the model's applicability in real-time control scenarios. To address this, the machine learning (ML) technique is integrated into the existing kMC framework. By training an artificial neural network (ANN) on the kMC data sets, we predict the probability distributions instead of repeatedly calculating them over time. Subsequently, the resulting ANN-accelerated multiscale kMC (AA-M-kMC) model is incorporated into a model predictive controller (MPC), facilitating real-time control of intricate lignin properties. This innovative approach effectively reduces the computational burden of kMC and advances lignin processing methods.

The novel incorporation of lignin-based systems for the preparation of antimicrobial cement composites

This paper, for the first time, presents a potential application of titanium(IV) oxide and silicon(IV) oxide combined with lignin through a solvent-free mechanical process as admixtures for cement composites. The designed TiO2-SiO2 (1:1 wt./wt.) hybrid materials mixed with lignin were extensively characterized using Fourier transform infrared spectroscopy (FTIR), electrokinetic potential analysis, thermal analysis (TGA/DTG), and porous structure properties. In addition, particle size distributions and scanning electron microscopy (SEM) were conducted to evaluate morphological and microstructural properties. In the next step, the effect of the TiO2-SiO2/lignin hybrid admixture on the workability, hydration process, microstructure, porosity, mechanical, and antimicrobial properties of the cement composites was evaluated. It was observed that appropriately designed hybrid systems based on lignin contributed to better workability, with an improvement of 25 mm, and reduced porosity of cement composites, decreasing from 14.4 % to 13.3 % in the most favorable sample. Additionally, a higher microstructure density was observed, and with increasing amounts of hybrid material admixture, the mechanical parameters also improved. In addition, the TiO2-SiO2/lignin hybrid systems had significant potential due to their high microbial purity, suggesting their effectiveness in minimizing microbial accumulation on surfaces. The final stage of analysis involved employing response surface methodology (RSM) to ascertain the optimum composition of cement composites. The results obtained indicate that the TiO2-SiO2/lignin admixtures are a promising approach for the valorization of lignin waste flows in the design of cement composites.

Cashew Phenol Modified Lignosulfonate Strategy for the Preparation of High-performance Dye Dispersants

Lignin-based dye dispersants (LDD), as one of the most common lignin resource end-application product, is difficult to meet the rapidly developing needs of modern fiber dyeing due to their inherent structural defects. The efficient upgrading and modification of LDD is of great significance to the value-added application of lignin resources and the expansion of LDD sinking market. In this study, using industrial kraft lignin as raw material, cashew phenol was introduced into lignosulfonate in the form of CC bonds by ingenious utilizing the structural characteristics of lignin disordered condensation. Aromatic ring in cashew phenol could provide sufficient sulfonic acid group grafting sites, while C15 fatty chain could enhance steric hindrance effect. In the dispersibility test, the dispersing power showed 99.09 %, and the low/high temperature dispersion (LTD/HTD) were 5 s/4 and 6 s/4, respectively, higher than the dispersibility level of LDD in the market, has great commercial value and industrial potential. Combined with FTIR, 1H NMR, GPC and ICP, the structural properties of lignin were analyzed in detail, and the degree of sulfonation-condensation was balanced-optimized. The CC bond condensation process between cashew phenol and lignin was revealed, and the mechanism of action on dye particles was elucidated.

Fractionation of Kraft Lignin for Production of Alkyd Resins for Biobased Coatings with Oxidized Lignin Dispersants as a Co-Product

A new valorization pathway based on solvent fractionation was applied to kraft lignin, a major by-stream of the pulping industry, to extract a soluble lignin intermediate featuring an improved structural homogeneity, a low molecular weight, and a high content of phenolic hydroxyl and carboxylic acid groups to serve as a substitute of the nonrenewable polyacids in the formulation of alkyd resins, a dominant material used in the production of anticorrosion surface coatings. Herein, softwood kraft lignin was mixed in a low-cost green solvent, aqueous ethanol, prepared at different ratios, at room temperature to generate a soluble fraction of a low M w of ≤2200 g mol-1 and an insoluble fraction of a high M w of ≥3950 g mol-1 of lignin. The best combination of yields and molecular weights of soluble lignin (16-36% yield, 1740-1890 g mol-1) was attained using 50-80 vol % ethanol in fractionation. Thus, these conditions were further employed at the pilot scale to demonstrate the scalability of this technology. Soluble lignin from pilot fractionation was used to produce an optimal alkyd resin formulation and thereafter an anticorrosion coating on the metal surface, both of which matched the target properties of industrial standards well (180 s Persoz hardness and 72 gloss units of coating, 100% adhesion of paint with no cracks or peeling in the cross-cut test, no corrosion after 120 h of the salt spray test). The insoluble solids from pilot fractionation could also be valorized by alkali-O2 oxidation into lignin-based dispersants for special carbon black pigments. Overall, this study presents a new, simple strategy to develop an efficient, scalable, low-cost, and green process for upgrading kraft lignin into phenolic intermediates for biobased alkyd resins to facilitate sustainable production of high-performance anticorrosion coatings.

Dye-Decolorizing Peroxidases Maintain High Stability and Turnover on Kraft Lignin and Lignocellulose Substrates

Fungal enzyme systems for the degradation of plant cell wall lignin, consisting of, among others, laccases and lignin-active peroxidases, are well characterized. Additionally, fungi and bacteria contain dye-decolorizing peroxidases (DyP), which are also capable of oxidizing and modifying lignin constituents. Studying DyP activity on lignocellulose poses challenges due to the heterogeneity of the substrate and the lack of continuous kinetic methods. In this study, we report the kinetic parameters of bacterial DyP from Amycolatopsis 75iv2 and fungal DyP from Auricularia auricula-judae on insoluble plant materials and kraft lignin by monitoring the depletion of the cosubstrate of the peroxidases with a H2O2 sensor. In the reactions with spruce, both enzymes showed similar kinetics. On kraft lignin, the catalytic rate of bacterial DyP reached 30 ± 2 s-1, whereas fungal DyP was nearly 3 times more active (81 ± 7 s-1). Importantly, the real-time measurement of H2O2 allowed the assessment of continuous activity for both enzymes, revealing a previously unreported exceptionally high stability under turnover conditions. Bacterial DyP performed 24,000 turnovers of H2O2, whereas the fungal DyP achieved 94,000 H2O2 turnovers in 1 h with a remaining activity of 40 and 80%, respectively. Using mass spectrometry, the depletion of the cosubstrate H2O2 was shown to correlate with product formation, validating the amperometric method.

Graphene oxide, starch, and kraft lignin bio-nanocomposite controlled-release phosphorus fertilizer: Effect on P management and maize growth

This study focuses on the synthesis and practical application of bio-nanocomposite films made from a mixture of starch (ST) and Kraft lignin (KL) with graphene oxide (GO) nanoparticles. FTIR, XRD, Raman, SEM, and TEM analysis confirmed the synthesis's success of GO. The bio-nanocomposites were used as advanced coatings for triple superphosphate (TSP) fertilizers, and their implications for maize (Zea mays L.) plant growth were examined. Incorporating GO into the composite matrix is a significant accomplishment of this study, as demonstrated by the noticeable changes observed in the FTIR spectra, indicating consequent structural changes. Morphological analyses conducted by SEM reveal changes in the surface characteristics of the ST/KL films, providing essential information about the structural details of the bio-nanocomposite. The utilization of precision-coated TSP fertilizers leads to a significant enhancement in mechanical strength, as demonstrated by the improved crush resistance. Furthermore, these formulations guarantee a gradual release of phosphorus, showcasing their potential for efficient nutrient management in agricultural settings. The study examines the practical application of coated TSP fertilizers in agriculture and their positive effects on various growth parameters of Maize (Zea mays L.) plants. Using these fertilizers promotes sustainable and efficient agricultural practices, contributing to developing innovative agrochemical solutions.

Crosslinking gelatin with robust inherent antibacterial natural polymer for wound healing

Gelatin-based biomaterials are widely acknowledged as a promising choice for wound dressings, given their similarity to the extracellular matrix and biocompatibility. However, the challenge of cross-linking gelatin while preserving its biocompatibility and cost-effectiveness persists. This study aimed to enhance the properties of gelatin by incorporating the oxidized lignosulfonate (OLS) biopolymer as an inexpensive and biocompatible natural material. The polyphenolic structure of OLS acts as both a cross-linking agent and an antibacterial component. The OLS/gelatin films were prepared using a casting method with varying weight ratios (0.1, 0.2, 0.3, 0.4, and 0.5 w/w). FTIR analysis confirmed the formation of Schiff-base and hydrogen bonds between gelatin and OLS. The resulting films exhibited enhanced mechanical properties (Young's modulus ∼40 MPa), no cytotoxicity, and excellent cell adhesion and morphology. Antimicrobial tests showed significant activity against Escherichia coli and Staphylococcus aureus, with higher activity against S. aureus (17 mm inhibition zone and 99 % bactericidal rate). In vivo studies in a mouse model demonstrated that the gelatin/0.2OLS dressing significantly improved wound healing, including re-epithelialization, collagen formation, inflammation reduction, and blood vessel density, compared to untreated wounds. These findings suggest that the synthesized novel gelatin/OLS wound dressing has promising healing and antibacterial properties.

Exploiting lignin-based nanomaterials for enhanced anticancer therapy: A comprehensive review and future direction

Lignin, a renewable and abundant natural polymer, has emerged as a promising candidate for anticancer therapy due to its unique properties and biocompatibility. This review provides a comprehensive overview of recent advancements in the utilization of lignin-based nanomaterials for enhancing anticancer drug delivery and therapeutic outcomes. A detailed examination of the literature reveals several synthesis methods, including nanoprecipitation, microemulsion, and solvent exchange, which produce lignin nanoparticles with improved drug solubility and bioavailability. The anticancer mechanisms of lignin nanoparticles, such as the generation of reactive oxygen species (ROS), induction of apoptosis, and enhanced cellular uptake, are also explored. Lignin nanoparticles loaded with drugs like curcumin, doxorubicin, camptothecin, and resveratrol have demonstrated the ability to improve drug efficacy, selectively target cancer cells, overcome multidrug resistance, and minimize toxicity in both in vitro and in vivo studies. These nanoparticles have shown significant potential in suppressing tumor growth, inducing cell death through apoptotic pathways, and enhancing the synergistic effects of combination therapies, such as chemo-phototherapy. Future research directions include optimizing lignin nanoparticle formulations for clinical applications, refining targeted delivery mechanisms to cancer cells, and conducting thorough biocompatibility and toxicity assessments. Overall, this review highlights the significant progress made in utilizing lignin-based nanomaterials for cancer therapy and outlines promising areas for further exploration in this rapidly evolving field.

Accessing monomers from lignin through carbon-carbon bond cleavage

Lignin, the heterogeneous aromatic macromolecule found in the cell walls of vascular plants, is an abundant feedstock for the production of biochemicals and biofuels. Many valorization schemes rely on lignin depolymerization, with decades of research focused on accessing monomers through C-O bond cleavage, given the abundance of β-O-4 bonds in lignin and the large number of available C-O bond cleavage strategies. Monomer yields are, however, invariably lower than desired, owing to the presence of recalcitrant C-C bonds whose selective cleavage remains a major challenge in catalysis. In this Review, we highlight lignin C-C cleavage reactions, including those of linkages arising from biosynthesis (β-1, β-5, β-β and 5-5) and industrial processing (5-CH2-5 and α-5). We examine multiple approaches to C-C cleavage, including homogeneous and heterogeneous catalysis, photocatalysis and biocatalysis, to identify promising strategies for further research and provide guidelines for definitive measurements of lignin C-C bond cleavage.

Statistics design for the synthesis optimization of lignin-sulfonate sulfur-doped mesoporous carbon materials: promising candidates as adsorbents and supercapacitors materials

This study employed lignin-sulfonated (LS) to develop biobased carbon materials (LS-Cs) through a sulfur-doping approach to enhance their physicochemical properties, adsorption capabilities, and energy storage potentials. Various characterization techniques, including BET surface area analysis, SEM imaging, XPS, Raman spectroscopy, and elemental composition (CHNS), were employed to assess the quality of the LS-Cs adsorbent and electrode samples. Response Surface Methodology (RSM) was utilized for optimizing the two main properties (specific surface area, ABET, and mesopore area, AMESO) by evaluating three independent factors (i.e., activation temperature, ZnCl2:LS ratio, and sulfur content). According to the statistical analysis, ABET and AMESO were affected by ZnCl2 and sulfur content, while the pyrolysis temperature did not affect the responses in the studied conditions. It was found that increasing the ZnCl2 and sulfur contents led to an increment of the ABET and AMESO values. The LS-C materials exhibited very high ABETvalues up to 1993 m2 g-1 and with predominantly mesoporous features. The S-doping resulted in LS-Cs with high sulfur contents in their microstructures up to 15% (wt%). The LS-C materials were tested as adsorbents for sodium diclofenac (DCF) adsorption and reactive orange 16 dye (RO-16) and as electrodes for supercapacitors. The LS-Cs exhibited excellent adsorption capacity values for both molecules (197-372 mg g-1) for DCF, and (223-466 mg g-1) for RO-16. When tested as electrodes for supercapacitors, notably, LS-C3, which is a doped sample with sulfur, exhibited the best electrochemical performance, e.g. high specific capacitance (156 F/g at 50 mV/s), and delivered an excellent capacitance after 1000 cycles (63 F/g at 1 A/g), which denotes the noteworthy capacitive behavior of the S-doped electrode. Thus, the present work suggests an eco-friendly resource for developing effective, productive carbon materials for adsorbent and electrodes for SC application. However, further studies on the complete application of these materials as adsorbents and electrodes are needed for a deeper understanding of their behavior in environmental and energy storage applications.

Lignin self-assembly phenomena and valorization strategies for pulping, biorefining, and materials development: Part 1. The physical chemistry of lignin self-assembly

Physical chemistry aspects are emphasized in this comprehensive review of self-assembly phenomena involving lignin in various forms. Attention to this topic is justified by the very high availability, low cost, and renewable nature of lignin, together with opportunities to manufacture diverse products, for instance, polymers/resins, bioplastics, carbon fibers, bio-asphalt, sunscreen components, hydrophobic layers, and microcapsules. The colloidal lignin material, nanoparticles, and microstructures that can be formed as a result of changes in solvent properties, pH, or other adjustments to a suspending medium have been shown to depend on many factors. Such factors are examined in this work based on the concepts of self-assembly, which can be defined as an organizing principle dependent on specific attributes of the starting entities themselves. As a means to promote such concepts and to facilitate further development of nano-scale lignin products, this article draws upon evidence from a wide range of studies. These include investigations of many different plant sources of lignin, processes of delignification, solvent systems, anti-solvent systems or other means of achieving phase separation, and diverse means of achieving colloidal stability (if desired) of resulting self-assembled lignin structures. Knowledge of the self-organization behavior of lignin can provide significant structural information to optimize the use of lignin in value-added applications. Examples include chemical conditions and preparation procedures in which lignin-related compounds of particles organize themselves as spheres, hollow spheres, surface-bound layers, and a variety of other structures. Published articles show that such processes can be influenced by the selection of lignin type, pulping or extraction processes, functional groups such as phenolic, carboxyl, and sulfonate, chemical derivatization reactions, solvent applications, aqueous conditions, and physical processes, such as agitation. Precipitation from non-aqueous solutions represents a key focus of lignin self-assembly research. The review also considers stabilization mechanisms of self-assembled lignin-related structures.

Mechanistic insights and applications of lignin-based ultraviolet shielding composites: A comprehensive review

Lignin is a green aromatic polymer constructed from repeating phenylpropane units, incorporating features such as phenolic hydroxyl groups, carbonyl groups, and conjugated double bonds that serve as chromophores. These structural attributes enable it to absorb a wide spectrum of ultraviolet radiation within the 250-400 nm range. The resulting properties make lignin a material of considerable interest for its potential applications in polymers, packaging, architectural decoration, and beyond. By examining the structure of lignin, this research delves into the structural influence on its UV-shielding capabilities. Through a comparative analysis of lignin's use in various UV-shielding applications, the study explores the interplay between lignin's structure and its interactions with other materials. This investigation aims to elucidate the UV-shielding mechanism, thereby offering insights that could inform the development of high-value applications for lignin in UV-shielding composite materials.

Nanolignin-Facilitated Robust Hydrogels

Recently, certain challenges and accompanying drawbacks have emerged in the preparation of high-strength and tough polymer hydrogels. Insights from wood science highlight the role of the intertwined molecular structure of lignin and crystalline cellulose in contributing to wood's strength. Herein, we immersed prestretched poly(vinyl alcohol) (PVA) polymer hydrogels into a solution of nanosized lignosulfonate sodium (LS), a water-soluble anionic polyelectrolyte, to creatively reconstruct this similar structure at the molecular scale in hydrogels. The nanosized LS effectively fixed and bundled the prestretched PVA polymers while inducing the formation of dense crystalline domains within the polymer matrix. Consequently, the interwoven structure of crystalline PVA and LS conferred good strength to the composite hydrogels, exhibiting a tensile strength of up to ∼23 MPa, a fracture strain of ∼350%, Young's modulus of ∼17 MPa, toughness of ∼47 MJ/m3, and fracture energy of ∼42 kJ/m2. This hydrogel far outperformed previous hydrogels composed directly of lignin and PVA (tensile strength <1.5 MPa). Additionally, the composite hydrogels demonstrated excellent antifreezing properties (<-80 °C). Notably, the LS-assisted reconstruction technology offers opportunities for the secondary fixation of PVA hydrogel shapes and high-strength welding of hydrogel components. This work introduces an approach for the high-value utilization of LS, a green byproduct of pulp production. LS's profound biomimetic strategy will be applied in multifunctional hydrogel fields.

Tough Supramolecular Hydrogels Crafted via Lignin-Induced Self-Assembly

Supramolecular hydrogels are typically assembled through weak non-covalent interactions, posing a significant challenge in achieving ultra strength. Developing a higher strength based on molecular/nanoscale engineering concepts is a potential improvement strategy. Herein, a super-tough supramolecular hydrogel is assembled by gradually diffusing lignosulfonate sodium (LS) into a polyvinyl alcohol (PVA) solution. Both simulations and analytical results indicate that the assembly and subsequent enhancement of the crosslinked network are primarily attributed to LS-induced formation and gradual densification of strong crystalline domains within the hydrogel. The optimized hydrogel exhibits impressive mechanical properties with tensile strength of ≈20 MPa, Young's modulus of ≈14 MPa, and toughness of ≈50 MJ m⁻3, making it the strongest lignin-PVA/polymer hydrogel known so far. Moreover, LS provides the supramolecular hydrogel with excellent low-temperature stability (<-60 °C), antibacterial, and UV-blocking capability (≈100%). Interestingly, the diffusion ability of LS is demonstrated for self-restructuring damaged supramolecular hydrogel, achieving 3D patterning on hydrogel surfaces, and enhancing the local strength of the freeze-thaw PVA hydrogel. The goal is to foster a versatile hydrogel platform by combining eco-friendly LS with biocompatible PVA, paving the way for innovation and interdisciplinarity in biomedicine, engineering materials, and forestry science.

Lignin: A valuable and promising bio-based absorbent for dye removal applications

The importance of environmental issues and the existence of humans have led to the recognition of environmental concerns as the main risk to modern life. Notably, one major concern for protecting and managing the environment and human health is the presence of dyes in wastewater. Therefore, before discharging wastewater into mainstream water, it is crucial to remove dyes. Among all lignocellulosic materials, lignin is a highly fragrant biopolymer. Its abundant availability, complex structure, and numerous functional moieties, including hydroxyl, carboxyl, and phenolic, are used in different chemicals and applications. Based on this, lignin is a very useful green material for adsorption, specifically in removing both heavy metals and organic pollutants from wastewater. This article describes the use of lignin-based adsorbents as a recent breakthrough in the removal of dye from aqueous solutions. On the other hand, the review intends to encourage readers to study both established and novel avenues in lignin-based dye removal materials.

Recovery of green phenolic compounds from lignin-based source: Role of ferulic acid esterase towards waste valorization and bioeconomic perspectives

The production of chemicals/products so far relies on fossil-based resources with the creation of several environmental problems at the global level. In this situation, a sustainable and circular economy model is necessitated to mitigate global environmental issues. Production of biowaste from various processing industries also creates environmental issues which would be valorized for the production of industrially important reactive and bioactive compounds. Lignin acts as a vital part in biowaste composition which can be converted into a wide range of phenolic compounds. The phenolic compounds have attracted much attention, owing to their influence on diverse not only organoleptic parameters, such as taste or color, but also active agents for active packaging systems. Crop residues of varied groups, which are an affluent source of lignocellulosic biomass could serve as a renewable resource for the biosynthesis of ferulic acid (FA). FA is obtained by the FA esterase enzyme action, and it can be further converted into various tail end phenolic flavor green compounds like vanillin, vanillic acid and hydroxycinnamic acid. Lignin being renewable in nature, processing and management of biowastes towards sustainability is the need as far as the global industrial point is concerned. This review explores all the approaches for conversion of lignin into value-added phenolic compounds that could be included to packaging applications. These valorized products can exhibit the antioxidant, antimicrobial, cardioprotective, anti-inflammatory and anticancer properties, and due to these features can emerge to incorporate them into production of functional foods and be utilization of them at active food packaging application. These approaches would be an important step for utilization of the recovered bioactive compounds at the nutraceutical and food industrial sectors.

Lignin-Based Composite Film and Its Application for Agricultural Mulching

Agricultural mulching is an important input for modern agricultural production and plays an important role in guaranteeing food security worldwide. At present, polyethylene (PE) mulching is still commonly used in agricultural production in most countries around the world, which is non-biodegradable, and years of mulching have caused serious agricultural white pollution. Lignin is one of the three major components of plant cell walls, and it is also the main renewable natural aromatic compounds in nature. Lignin-based composite film materials are green, biodegradable, and show good prospects for development in the field of agricultural mulch. This paper introduces the types, structure, and application status of lignin, summarizes the preparation of lignin-based composite film materials and its latest research progress, focuses on the types, preparation methods, and application examples of lignin-based agricultural mulching, and looks forward to the future development prospects of lignin-based agricultural mulching.

Sprayed water-based lignin colloidal nanoparticle-cellulose nanofibril hybrid films with UV-blocking ability

In the context of global climate change, the demand for new functional materials that are sustainable and environmentally friendly is rapidly increasing. Cellulose and lignin are the two most abundant raw materials in nature, and are ideal components for functional materials. The hydrophilic interface and easy film-forming properties of cellulose nanofibrils make them excellent candidates for natural biopolymer templates and network structures. Lignin is a natural UV-shielding material, as it contains a large number of phenolic groups. In this work, we have applied two routes for spray deposition of hybrid films with different laminar structures using surface-charged cellulose nanofibrils and water-based colloidal lignin particles. As the first route, we prepare stacked colloidal lignin particles and cellulose nanofibrils hybrid film through a layer-by-layer deposition. As the second route, we spray-deposite premixed colloidal lignin particles and cellulose nanofibrils dispersion to prepare a mixed hybrid film. We find that cellulose nanofibrils act as a directing agent to dominate the arrangement of the colloidal lignin particles in a mixed system. Additionally, cellulose nanofibrils eliminate the agglomerations and thus increase the visible light transparency while retaining the UV shielding ability. Our research on these colloidal lignin and cellulose nanofibril hybrid films provides a fundamental understanding of using colloidal lignin nanoparticles as functional material on porous cellulose-based materials, for example on fabrics.

Unlocking the potential: Evolving role of technical lignin in diverse applications and overcoming challenges

Recent advancements have transformed lignin from a byproduct into a valuable raw material for polymers, dyes, adhesives, and fertilizers. However, its structural heterogeneity, variable reactive group content, impurities, and high extraction costs pose challenges to industrial-scale adoption. Efficient separation technologies and selective bond cleavage are crucial. Advanced pretreatment methods have enhanced lignin purity and reduced contamination, while novel catalytic techniques have improved depolymerization efficiency and selectivity. This review compares catalytic depolymerization methodologies, highlighting their advantages and disadvantages, and noting challenges in comparing yield values due to variations in isolation methods and lignin sources. Recognizing "technical lignin" from pulping processes, the review emphasizes its diverse applications and the necessity of understanding its structural characteristics. Emerging trends focus on bio-based functional additives and nanostructured lignin materials, promising enhanced properties and functionalities. Innovations open possibilities in sustainable agriculture, high-performance foams and composites, and advanced medical applications like drug delivery and wound healing. Leveraging lignin's biocompatibility, abundance, and potential for high-value applications, it can significantly contribute to sustainable material development across various industries. Continuous research in bio-based additives and nanostructured materials underscores lignin's potential to revolutionize material science and promote environmentally friendly industrial applications.

Bio-derived carbon-based materials for sustainable environmental remediation and wastewater treatment

Biosynthesized nanocomposites, particularly those incorporating carbon-based materials, exhibit exceptional tunability and multifunctionality, surpassing the capabilities of conventional materials in these aspects. Developing practical solutions is critical to address environmental toxins from pharmaceuticals, heavy metals, pesticides, and dyes. Biomass waste is a readily available carbon source, which emerges as a promising material for producing biochar due to its inherent advantages: abundance, low cost, and environmentally friendly nature. This distribution mainly uses carbon-based materials (CBMs) and biomass waste in wastewater treatment. This review paper investigates several CBM types, including carbon aerogels, nanotubes, graphene, and activated carbon. The development of bio-derived carbon-based nanomaterials are discussed, along with the properties and composition of carbon materials derived from biomass waste and various cycles, such as photodegradation, adsorption, and high-level oxidation processes for natural remediation. In conclusion, this review examines the challenges associated with biochar utilization, including cost, recovery, and practical implementation.

Preparation of a high-performance conductive lignocellulose hydrogel by directly using non-detoxified bisulfite-pretreated corncob

Biomass-based hydrogels have become a research hotspot because of their better biocompatibility. However, the preparation of biomass hydrogels is complicated, and they often need to be modified by introducing other substances. In this study, corncob pretreated with bisulfite (125-185 °C) was used as a raw material to prepare lignocellulose hydrogels. The results showed that directly using the pretreated sample without the washing step lowered the total hydrogel costs while preserving the lignosulfonate (LS) produced during pretreatment. The best tensile (54.1 kPa) and compressive (177.7 kPa) stresses were obtained for the hydrogel prepared from non-detoxified pretreated corncob at 165 °C (NCH-165). The sulfonic acid groups in LS could enhance the interaction between plant cellulose, thus improving its mechanical properties. The capacitor assembled from NCH-165 achieved an energy density of 236.1 Wh/kg at a power density of 499.7 W/kg and a high coulombic efficiency of more than 99 % after 2000 charge/discharge cycles. In conclusion, the present study simplifies the pathway for the preparation of flexible, conductive, and anti-freezing hydrogels by directly utilizing a non-detoxified bisulfite-pretreated corncob.

Wood inspired biobased nanocomposite films composed of xylans, lignosulfonates and cellulose nanofibers for active food packaging

The growing concerns on environmental pollution and sustainability have raised the interest on the development of functional biobased materials for different applications, including food packaging, as an alternative to the fossil resources-based counterparts, currently available in the market. In this work, functional wood inspired biopolymeric nanocomposite films were prepared by solvent casting of suspensions containing commercial beechwood xylans, cellulose nanofibers (CNF) and lignosulfonates (magnesium or sodium), in a proportion of 2:5:3 wt%, respectively. All films presented good homogeneity, translucency, and thermal stability up to 153 °C. The incorporation of CNF into the xylan/lignosulfonates matrix provided good mechanical properties to the films (Young's modulus between 1.08 and 3.79 GPa and tensile strength between 12.75 and 14.02 MPa). The presence of lignosulfonates imparted the films with antioxidant capacity (DPPH radical scavenging activity from 71.6 to 82.4 %) and UV barrier properties (transmittance ≤19.1 % (200-400 nm)). Moreover, the films obtained are able to successfully delay the browning of packaged fruit stored over 7 days at 4 °C. Overall, the obtained results show the potential of using low-cost and eco-friendly resources for the development of sustainable active food packaging materials.

Effect of Lignosulphonates on the Moisture Resistance of Phenol-Formaldehyde Resins for Exterior Plywood

Phenol-formaldehyde (PF) resins remain the preferred adhesive for exterior plywood, as they confer these boards their extreme weather resistance. However, their high price and toxicity has made phenol alternatives, such as technical lignins, increasingly more attractive. While many works report the use of kraft lignin, the most commercially available form are lignosulphonates (LS). However, these lack industrial success and are associated with low moisture resistance. In the current study, lignosulphonate-phenol-formaldehyde (LPF) resoles were synthesized considering a phenol replacement of 30% (w/w). Two LS samples of softwood (SLS) and hardwood (HLS) origin were compared. These samples were previously methylolated to increase their reactivity. The effectiveness of the treatment was confirmed through the Automated Bonding Evaluation System. Plywood was manufactured and tested according to EN 314 class 3 for exterior conditions, which is seldom found in the literature. Although a 35% increase in shear strength is still necessary to comply with the standard, methylolated SLS was the most promising substitute, as it resulted in the highest board performance. Notably, when this sample was used without previous methylolation, the plywood boards suffered delamination during immersion in boiling water prior to shear testing. These results reinforce the need for the methylolation of LS to increase the weather resistance of plywood.

Recent advance in preparation of lignin nanoparticles and their medical applications: A review

BACKGROUND

Lignin has attracted a lot of attention because it is non-toxic, renewable and biodegradable. Lignin nanoparticles (LNPs) have high specific surface area and specific surface charges. It provides LNPs with good antibacterial and antioxidant properties. LNPs preparation has become clear, however, the application remains in the early stages.

PURPOSE

A review centric research has been conducted, reviewing existing literature to accomplish a basic understanding of the medical applications of LNPs.

METHODS

Initially, we extensively counseled the heterogeneity of lignin from various sources. The size and morphology of LNPs from different preparation process were then discussed. Subsequently, we focused on the potential medical applications of LNPs, including drug delivery, wound healing, tissue engineering, and antibacterial agents. Lastly, we explained the significance of LNPs in terms of antibacterial, antioxidant and biocompatibility, especially highlighting the need for an integrated framework to understand a diverse range of medical applications of LNPs.

RESULTS

We outlined the chemical structure of different type of lignin, and highlighted the advanced methods for lignin nanoparticles preparation. Moreover, we provided an in-depth review of the potential applications of lignin nanoparticles in various medical fields, especially in drug carriers, wound dressings, tissue engineering components, and antimicrobial agents.

CONCLUSION

This review provides a detailed overview on the current state and progression of lignin nanoparticles for medical applications.