Search Results (457)

Rice husk (RH) is a renewable siliceous lignocellulosic waste providing a unique, greener and less toxic alternative to conventional synthetic polymeric precursors in the production of carbon-based materials for biomedical applications. In this work we studied the porous structure of RH-lignin-based activated carbon produced in the form of honeycomb carbon monoliths and assessed their potential as hemoadsorbents for blood purification in the treatment of patients with serious medical conditions, such as kidney failure and sepsis. To determine their clinical suitability for such an application, the hemocompatibility and cytotoxicity of the monoliths were investigated using the standard ISO guidelines. The monoliths did not cause any changes in the cell viability or cell lysis. High micro/mesoporosity and surface chemistry of the initial monolith-C, N- and P-doped nanostructured carbon honeycomb monoliths were established by low-temperature nitrogen adsorption (LTNA) studies, mercury porosimetry data (MIP), SEM/EDS analysis and FT-IR spectroscopy. The micro-mesoporous, activated carbon-based filtration/adsorbent prototype devices, in the form of three-dimensional (3D) carbon matrix, functionalized with ion-exchange amino- and phosphate groups and encased in polyolefin heat shrink cable sleeve, have been developed with the capacity to remove protein-bound uremic toxins (PBUTs), such us PCS and IS, as well as inflammatory cytokines (IL-6 and IL-8) from human plasma in a flowing model system. The ammoxidized monolith-N, derived from the monolith-C, had the highest removal efficiency (40.05% for PCS, and 28.4% for IL-6). By contrast, phosphorylated monolith-P demonstrated the highest removal efficiency (54.62% for IS, and 54.4% for IL-8), whilst the monolith-C has the lowest removal efficiency for these adsorbates. These results do not correlate with the LTNA and MIP study results, suggesting that the interaction of surface chemical functional groups with the solutes play key roles in the adsorption mechanism. The ion-exchange mechanism of PBUTs and inflammatory cytokine chemisorption by the monoliths, modified with surface N- and P-containing functional groups, has been proposed. Full article

Traditional phenol-formaldehyde (PF) resin adhesives rely on petroleum-based phenolic monomers, facing dual pressures from resource constraints and environmental concerns. Lignin, an abundant renewable aromatic polymer in wood cell walls with a molecular structure rich in phenolic hydroxyl groups, serves as an ideal bio-based precursor for producing green PF resins. Developing lignin-based phenol-formaldehyde (LPF) resins not only enables the high-value utilization of forest biomass but also aligns with sustainable development strategies. However, the large-scale industrial application of lignin remains challenging due to its inherent drawbacks, such as low reactivity. This review focuses on lignin-modified PF resins, systematically summarizing the main physicochemical modification methods—including phenolation, hydroxymethylation, demethylation, and depolymerization activation—along with their mechanisms of influence on resin properties. It compares and discusses the advantages and disadvantages of different modification routes, analyzes current key technical bottlenecks, and prospects future development directions, aiming to provide a reference for research and application of forest-based green adhesive materials. This review concludes that the combination of physical pretreatment and targeted chemical modification is the most promising approach for enhancing lignin reactivity and resin performance. Future research should prioritize developing green modification technologies, such as those based on deep eutectic solvents (DESs) and aqueous systems, and establish quantitative structure–property relationships for lignin-based resins to accelerate the transition of lignin-based phenolic resins from laboratory research to industrial-scale production. Full article

The conversion of paper-based industrial residues into lignin-containing cellulose micro/nanofibrils (LCMNFs) provides an opportunity to combine resource valorization with improved adhesive formulations. This study investigated LCMNF produced from alkaline-pretreated unbleached paper tube residues as reinforcement for formaldehyde-free sodium silicate (SS) adhesive, using polyethylene glycol 400 as a dispersing agent. LCMNF was incorporated at 0.5–2.0 wt%, and the rheological, mechanical, and fracture behavior of the modified adhesives was evaluated. Increasing LCMNF content increased viscosity, yield stress, and storage modulus, indicating increased structural resistance within the SS matrix, while all formulations retained the shear-thinning behavior required for processing. Mechanical performance was strongly concentration-dependent. At 0.5 wt%, LCMNF significantly increased strain at break by approximately 40%, whereas 1.0 wt% increased shear modulus by 41%. Both concentrations significantly increased energy to failure without compromising shear strength and exhibited more tortuous fracture morphologies than the neat SS adhesive. Higher LCMNF contents increased microstructural heterogeneity and reduced shear strength. Overall, 1.0 wt% LCMNF provided the most favorable balance of rheological, mechanical, and fracture properties, demonstrating the potential of residue-derived LCMNF for reinforcing SS adhesives and for reintegration into the paper tube production chain. Full article

Sunflower hulls are an abundant lignocellulosic waste with significant but underexploited potential for the recovery of high-value compounds and production of renewable energy. In this study, an integrated biorefinery approach was developed for the sequential recovery of waxes, free and bound phenolic compounds, and biomethane. Three pretreatment strategies (acid-thermal, mechanically assisted alkaline, and ultrasound-assisted ethanolic) were comparatively evaluated to determine their effects on bound phenolics extraction and biomethane production. Sequential extraction recovered 0.94 g of waxes 100 g⁻¹ d.b. and 145.52 mg GAE 100 g⁻¹ d.b. of free phenolics, with chlorogenic acid as the predominant compound. The different pretreatments exhibited contrasting performances depending on the valorisation criterion considered. Although acid–thermal pretreatment achieved the highest recovery of bound phenolic compounds (99.3 mg GAE 100 g⁻¹ d.b.), ultrasound-assisted ethanolic pretreatment preserved the largest proportion of the original biomass and resulted in the highest overall methane recovery (150% relative to the untreated biomass). Each pretreatment modified the lignocellulosic matrix through hemicellulose solubilization, lignin disruption, and fibre reorganisation, thus explaining the observed differences in phenolic release and biomethane production. The results demonstrate that each pretreatment favours a specific product stream, and that the selection of the most suitable pretreatment depends on the biorefinery’s objective. Full article

In this work, a formaldehyde-free bio-based wood adhesive was successfully fabricated using epoxidized soybean oil (ESO) cross-linked with maleic anhydride (MA) and carboxylated lignin sulfonate (CLS). The effect of CLS substitution dosage on the bonding performance was systematically investigated. The results indicated that the dry shear strength and wet shear strength of the adhesive exhibited a typical non-monotonic variation with increasing CLS content, reaching the maximum values of 1.79 MPa and 1.38 MPa, respectively, at a CLS substitution ratio of 40 mol% relative to MA. These mechanical properties fully meet and exceed the requirements of the Chinese national standard for wood adhesives. Orthogonal experiments were further conducted to optimize the hot-pressing process parameters and the optimal conditions were determined as follows: hot-pressing temperature of 130 °C, pressing time of 10 min, glue spread of 280 g/m², and pre-mixing time of 70 min. FTIR, DSC, and TGA characterizations confirmed the complete curing reaction of the adhesive system. The introduced CLS served as both a reactive curing agent and an efficient catalytic component, which effectively reduced the curing temperature, while the incorporation of MA significantly improved the thermal stability of the cured adhesive. This study provides a feasible strategy for the preparation of high-performance, low-cost, and environmentally friendly bio-based wood adhesives. Full article

This study investigates the effect of Arundodonax L.-derived lignin on the rheological behaviour, mechanical performance and oxidative ageing resistance of bitumen. Arundo donax is a fast-growing invasive grass with high lignin content, representing a promising sustainable biomass source for bitumen modification. Lignin was extracted via the Acid Detergent Lignin method, yielding a fine powder (50–300 μm). The incorporation of 6 wt% lignin into a 35/50 paving-grade bitumen induced significant changes in binder behaviour. Infrared spectroscopy (FTIR) confirmed the polyaromatic and oxygenated nature of lignin and indicated that its interaction with bitumen is primarily physical, involving polar intermolecular interactions rather than chemical bonding. Lignin modification significantly increased stiffness, elasticity, and rutting resistance, as evidenced by higher softening point, complex modulus, and recovery after creep loading. Furthermore, FTIR analysis confirmed a reduced susceptibility to oxidative ageing, demonstrated by lower increases in carbonyl and sulfoxide indexes after ageing. This suggests distinct antioxidant activity associated with the phenolic structures of lignin. Despite these benefits, severe long-term ageing led to a marked reduction in fatigue life, ductility, low-temperature cracking resistance, and adhesive properties. Overall, these results demonstrate that Arundo donax-derived lignin is a promising sustainable modifier for bitumen, though optimisation of the dosage and blending conditions is necessary to balance durability against long-term fracture performance. Full article

Postharvest lignification and microbial spoilage limit the shelf life of arrow bamboo shoots. This study evaluated the effects of electrolyzed functional water (EFW) combined with spontaneous modified-atmosphere (MA) packaging (EFW+MA) on postharvest quality and associated physiological, metabolic, and microbial changes. EFW+MA reduced weight loss, decay incidence, and browning while maintaining firmness and color. It also reduced lignin and cellulose accumulation, accompanied by lower activities of phenylalanine ammonia-lyase (PAL), peroxidase (POD), and polyphenol oxidase (PPO). Untargeted liquid chromatography–tandem mass spectrometry (LC-MS/MS) metabolomics showed that storage-associated metabolic changes were moderated by EFW+MA, including lower abundances of phenylalanine and tyrosine in the treated samples. In addition, EFW+MA enhanced superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activities, reduced malondialdehyde (MDA) accumulation, and alleviated membrane lipid peroxidation. 16S ribosomal RNA (16S rRNA) gene sequencing showed that EFW+MA reduced operational taxonomic unit (OTU) richness and altered bacterial community composition, including lower relative abundances of Campylobacterota and Enterobacteriaceae and a higher relative abundance of Lactobacillaceae. Overall, EFW+MA delayed postharvest quality deterioration of arrow bamboo shoots, accompanied by changes in lignification-related physiology, oxidative defense, metabolite profiles, and bacterial communities. Full article

Natural macromolecules and biopolymers are central components in biological, food, pharmaceutical, and materials systems. Pectins, polysaccharides, cellulose, lignin, chitin, chitosan, polyhydroxyalkanoates, proteins, and macromolecular complexes can be recovered from renewable matrices or modified to obtain specific technological functions. Hydrodynamic cavitation is assessed as an intensification platform for the recovery and processing of these fractions. Attention is directed to the relationship between process configuration, molecular structure, and final performance. Extraction yield alone is not considered sufficient to define the technological value of the treatment. Matrix disintegration, mass transfer, dispersion, emulsification, fibrillation, controlled depolymerization, and structural modification are considered. Reactor configuration, operating severity, fraction stability, molecular characterization, rheological properties, colloidal behavior, energy consumption, and scale-up transferability are also evaluated. The available evidence, including representative quantitative and functional descriptors reported in the literature, indicates that hydrodynamic cavitation should not be interpreted as a universally superior technology. Its relevance is stronger when a measurable, reproducible, and functionally meaningful advantage is demonstrated against appropriate controls and alternative technologies. Full article

Driven by the goals of carbon peaking and carbon neutrality, as well as the increasing demand for green construction materials, traditional petroleum-based asphalt can no longer fully meet the requirements of long-life and low-carbon road construction due to its strong resource dependence, susceptibility to aging, and difficulty in balancing high- and low-temperature performance. Bio-based polyurethane-modified asphalt (Bio-PUMA) uses renewable or waste biomass to construct high-performance polyurethane (PU) networks, providing a new way to improve pavement performance, reduce carbon emissions, and support the sustainable development of road materials. This paper reviews the molecular structural characteristics of bio-based precursors, including vegetable oil, rosin, and lignin, and summarizes their effects on PU network formation, asphalt microphase morphology, and pavement performance. Existing studies show that the functionality, molecular backbone, hydroxyl value, and soft-to-hard segment ratio of bio-based polyols govern the crosslinking density, phase continuity, and asphalt compatibility of polyurethane networks, thereby influencing rutting resistance, cracking resistance, aging resistance, interfacial adhesion, and mixture performance. Current challenges include unstable biomass feedstocks, difficulty in balancing low-temperature toughness and high-temperature strength, limited long-term service data, and incomplete life-cycle assessment. Future studies should focus on precursor standardization, precise molecular design, multiscale performance evaluation, and engineering validation to promote the application of Bio-PUMA in long-life, low-carbon, and large-scale road infrastructure. Full article

The growing demand for environmentally sustainable materials has accelerated the development of bio-based coatings as alternatives to conventional petroleum-derived surface treatments. Among renewable biopolymers, lignin has emerged as a particularly attractive candidate owing to its abundance, renewable origin, aromatic structure, antioxidant activity, ultraviolet shielding capability, and diverse functional groups suitable for chemical modification. As a major by-product of the pulp, paper, and biorefinery industries, lignin represents an underutilized renewable resource with significant potential for value-added coating applications. This review provides an overview of recent advances in lignin-based coatings for sustainable and biodegradable materials. The chemical structure, physicochemical properties, industrial sources, extraction technologies, purification methods, and functionalization strategies of lignin are discussed. Particular attention is given to nanostructured lignin systems, including lignin nanoparticles (LNPs) and chemically modified derivatives, which have demonstrated improved compatibility and performance in coating formulations. Fabrication technologies such as solution casting, dip coating, spray coating, layer-by-layer (LbL) assembly, extrusion processing, and nanocomposite approaches are examined. Mechanical, barrier, thermal, UV-shielding, antioxidant, antimicrobial, hydrophobic, and environmental performance are comparatively assessed. Lignin nanoparticles and chemically modified lignins generally show improved functionality, while waterborne coatings for paper and fiber-based packaging appear closest to practical application. However, lignin heterogeneity, durability, scalability, and limited regulatory evaluation and end-of-life assessment remain major barriers to commercialization. Full article

Soil microbial carbon use efficiency (CUE) and nitrogen use efficiency (NUE) are fundamental parameters governing organic matter turnover in terrestrial ecosystems, yet how forest type-driven variation in litter quality propagates through the litter–soil–microbe continuum to regulate these efficiencies remains poorly resolved. Across three forest types in the Funiu Mountains, central China—a Larix gmelinii (LG) plantation, a Quercus aliena var. acuteserrata (QA) secondary forest, and a mixed Quercus aliena var. acutiserrata and Pinus armandii (QP) forest—we quantified litter chemistry, soil physicochemical properties, microbial biomass, extracellular enzyme activities, and microbial nutrient use efficiencies (MUE: NUE, and phosphorus use efficiency, PUE) derived from a modified saturation kinetics model. Principal coordinate analysis revealed significant multivariate differentiation among forest types across litter, soil, microbial biomass, and enzyme modules (Adonis R² = 0.198–0.427; all p < 0.05). Compared with LG and QA, QP exhibited a pronounced stoichiometric imbalance: it supported the highest litter organic carbon and total nitrogen, the lowest lignin-to-cellulose ratio, the largest soil C and N pools (SOC and STN), and the greatest microbial biomass carbon (MBC). However, despite this resource-rich environment, microbial biomass C:N:P ratios exhibited constrained variation, while soil C:P (SCP) and N:P ratios (SNP) in QP reached extreme values (112.3 and 7.25, respectively), generating severe stoichiometric imbalance. Vector analysis indicated that all forests were under relative nitrogen limitation (vector angle < 45°), with QP showing the strongest limitation (41.6 ± 0.4°). Critically, QP exhibited the highest NUE (0.47 ± 0.03) but the lowest CUE (0.95 ± 0.01), and CUE and NUE were nearly perfectly negatively correlated across all sites (R = −0.98, p < 0.001). Random forest analysis identified extracellular enzyme stoichiometry as the dominant proximate predictor of MUE. Partial least squares structural equation modeling (GOF = 0.673–0.674; R² = 0.592–0.603) revealed that litter and soil properties had no significant direct effects on CUE or NUE; instead, soil nutrients exerted strong indirect association through a cascade—soil → microbial biomass → enzyme activity—with opposite total effects on CUE (−0.731, p < 0.001) versus NUE (+0.755, p < 0.001). These findings reveal that the same soil nutrient enrichment that accompanies mixed-species afforestation drives divergent microbial metabolic responses—suppressing CUE while promoting NUE—through a shared cascading structure, with implications for predicting soil carbon and nutrient retention under shifting forest compositions. Full article

The chemically modified ammonium lignosulfonate (ALS) powders with carboxylic acids such as, oleic (OA) and lactic acid (LA) and γ-butyrolactone (BL) under dielectric barrier plasma discharge (DBD) have been characterized by average molecular weight and particle size determinations, morphology examination by optical and electronic microscopy (SEM), the study of the thermal properties by thermogravimetry (TG/DTG), differential scanning calorimetry (DSC), differential thermal analysis (DTA) and antioxidant activity tests by DPPH method. The thermal characterization of the modified lignosulfonates reveals their improved thermal stability comparatively with ALS. It has been established that the obtained microparticles are aggregates of particles, covered by modified polymer and exhibit a particular behavior depending on the chemical structure of the used modifier, leading to multifunctional active lignin-based products with better homogeneity. By surface modification, the antioxidant capacity of modified lignosulfonate powders has been maintained. Full article

The application of lignin as a sustainable replacement for phenol in resin is one of the main priorities in the polymer industry. The partial substitution of phenol by Kraft lignin in the synthesis of resole resin, a mineral and glass wool insulation binder, was thus investigated. Lignin was activated by phenolation in an alkaline medium at low temperature, followed by reaction with formaldehyde in the same batch. Conducting the phenolation reaction in an alkaline medium allows the synthesis of resol resin to continue without interrupting the process, while the low temperature ensures the low viscosity of the synthesized resol, which is a prerequisite for its use as a binder in the manufacture of thermal insulation products. This is an important innovation that streamlines the production of modified resol. Activated lignin and resole resins were characterized by Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). Phenolation occurs mainly via the binding of phenol to the lignin macromolecule, increasing the molecular weight of activated lignin, with only small amounts of low molecular weight species observed. Resol resins with and without incorporated lignin have identical FTIR spectra and similar molecular weight distributions, which confirms the successful synthesis of lignin-containing resin. With essential relevance for the undisturbed production of thermal insulation products, the most suitable of the resins synthesized with lignin has appropriate viscosity, double the stability of the reference product, and half the amount of tetradimer (tetradimer can cause problems due to precipitation). In addition, this resin results in significantly lower emissions and has increased flexural strength. The synthesis is transferable to industrial practice. Full article

The development of bio-based adhesives has emerged as a viable strategy to reduce fossil-derived resin consumption in wood and wood-based panel applications. This review provides a polymer-focused assessment of adhesive systems derived from proteins, carbohydrates, lignin, and tannins, emphasizing molecular architecture, crosslinking chemistry, interfacial interactions, and structure–property relationships. Adhesive performance is primarily dictated by functional group density, crosslinking efficiency, and network topology. Protein-based adhesives rely on hydrogen bonding and covalent crosslinking with lignocellulosic substrates but require structural modification to improve hydrothermal stability. Carbohydrate-based systems, including starch and cellulose derivatives, offer reactive hydroxyl functionalities that enable oxidation, esterification, and etherification pathways for enhanced network formation. Lignin and tannins, characterized by phenolic and aromatic structures, facilitate condensation reactions and enable partial substitution of phenol in thermosetting resins, supporting low-formaldehyde or formaldehyde-free formulations. Hybrid polymer networks, particularly protein–carbohydrate and lignin-modified systems, demonstrate improved crosslink density, reduced hydrophilicity, and enhanced mechanical performance. Life cycle analyses indicate that increasing biogenic carbon content and minimizing fossil-based cross-linkers can lower global warming potential (GWP) and volatile organic compound (VOC) emissions. Overall, a structure–property–sustainability framework is proposed to guide molecular design and performance optimization of next-generation bio-based wood adhesives. Full article

Coconut husk lignin was fractionated using ethanol to obtain nanolignin fractions with distinct physicochemical properties. Among the fractions, CNF1 exhibited the most favorable combination of particle size, thermal stability, and antibacterial activity and was selected for further modification. Microwave-assisted esterification of CNF1 with maleic anhydride was performed under various reaction temperatures and lignin-to-maleic anhydride ratios. Structural modification was confirmed by ATR-FTIR spectroscopy through the appearance of ester carbonyl groups and an increase in the degree of esterification, which reached its highest value at 180 °C and a lignin-to-maleic anhydride ratio of 1:10. TEM analysis revealed that maleation increased nanoparticle size, whereas WAXD demonstrated that both native and modified lignins retained predominantly amorphous structures. Antioxidant activity decreased with increasing esterification due to the reduction of phenolic hydroxyl groups. Thermal analysis showed that esterification altered the degradation behavior of lignin, while thermo-oxidative stability measurements indicated improved oxidation resistance for highly esterified samples. The 10MA180 sample exhibited the highest thermo-oxidative stability, with a T₂,O₂ value of 12.55 min, a residual mass of 84.90%, and the lowest weight loss after 60 min oxidation. These findings demonstrate that microwave-assisted maleation effectively tailors the structure and functional properties of nanolignin for sustainable bio-based material applications. Full article