Search Results (1,153)

The extraction of cellulose from underutilized forest residues can diversify bio-based material supply chains and reduce pressure on commercial pulps. In this study, cellulose was isolated from Tibouchina lepidota (Bonpl.) Baill pruning residues through an alkaline–acid–oxidative protocol, and its suitability for polymeric applications was evaluated. Two granulometric fractions (250 µm and 125 µm) were used; the yields were 4.73 ± 0.12 g and 3.62 ± 0.11 g per 50 g of biomass, equivalent to 90.5% and 92.8% recovery, respectively (fractional remains as bleached pulp after removal of non-cellulosic components). Fourier Transform Infrared spectroscopy (FTIR) showed the disappearance of lignin and hemicelluloses bands and a pronounced β-glucopyranosic signal at 894 cm⁻¹, indicating high purity. Selective solubility in 17.5% NaOH classified the polymer as β-cellulose, suitable for wet spinning and film regeneration. Optical microscopy revealed smooth fibers of 25–50 µm length and 0.5–1 µm diameter, with aspect ratios ≥ 50, indicating favorable morphology for load transfer in composites. Statistical analysis (Shapiro–Wilk, F-test, and Student’s t-test) confirmed the significant influence of particle size on yield (p < 10⁻¹⁵). Overall, T. lepidota residues constitute a viable source of high-purity β-cellulose, whose molecular integrity and microstructure satisfy the requirements of sustainable polymeric manufacturing. Full article

The growing demand for sustainable biorefinery approaches calls for efficient, environmentally benign strategies to valorize agricultural residues and ensure their complete utilization. This study explores the combination of deep eutectic solvents (DESs) and microwave heating technology as a greener process for the selective fractionation of agri-food waste residues in a zero-waste perspective. Within this framework, five representative biomasses were thoroughly investigated, namely brewer’s spent grain, raw and parboiled rice husks, rapeseed cakes, and hemp hurds. DES formulation was selected for its ability to solubilize and separate lignocellulosic components, enabling the recovery of a polysaccharide-rich fraction, lignin, and bioactive compounds. DES extraction was performed using both microwave heating and conventional batch heating, enabling a direct comparison of the two methods, the optimization of a more sustainable fractionation process, and the maximization of yields while preserving the functional integrity of the recovered fractions. A comprehensive characterization of the separated fractions was carried out, revealing that the two fractionation methods do not yield significant differences in the composition of the primary components. Moreover, a ¹³C CP-MAS NMR analysis of the recovered lignins demonstrates how this analytical technique is a real fingerprint for the biomass source. The results demonstrate the great potential of microwave DES-mediated fractionation as a mild, tunable, and sustainable alternative to conventional methods, aligning with green chemistry principles and opening new approaches for the full valorization of waste byproducts Full article

Driven by the growing demand for sustainable materials, spent coffee grounds have emerged as a promising bio-based reinforcement in polymer composites, particularly for additive manufacturing applications. As a readily available byproduct of the coffee industry, spent coffee grounds contain cellulose, hemicellulose, lignin, proteins, and oils, making them attractive fillers for both thermoplastic and thermoset matrices. Incorporating spent coffee grounds into composites supports waste valorization, cost reduction, and environmental sustainability by transforming organic waste into functional materials. This review first examines the issue of spent coffee ground waste, addressing its environmental footprint and disposal challenges. It then explores the composition and properties of spent coffee grounds. The paper provides a comprehensive overview of composites based on spent coffee grounds for 3D printing, covering processing methods, potential applications, and current challenges in additive manufacturing. Special attention is given to the preparation and processing of these composites, including key steps such as drying, grinding, sieving, and surface modification to enhance compatibility with polymer matrices. Various additive manufacturing techniques influence the printability, processability, and mechanical performance of such composites. While spent coffee grounds offer notable sustainability advantages, challenges such as weak interfacial adhesion, moisture sensitivity, and reduced mechanical properties necessitate optimized processing conditions, surface treatments, and tailored material formulations. This review highlights recent advancements and outlines future research directions, emphasizing the need for stronger interactions between spent coffee grounds and polymer matrices, improved recyclability, and scalable additive manufacturing solutions to establish spent coffee grounds as a viable and eco-friendly alternative for 3D printing applications. Full article

This study presents a comprehensive investigation of a novel graphene oxide/zinc oxide/lignin (GO/ZnO/lignin) nanocomposite for the photocatalytic degradation of methylene blue (MB) and gentian violet (also known as crystal violet, CV) dyes in aqueous solutions. The nanocomposite was synthesized through a hydrothermal method and thoroughly characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). FTIR spectra confirmed the successful incorporation of functional groups from all components, while XRD patterns revealed a well-crystallized structure with characteristic peaks. SEM micrographs showed a uniform, hierarchical morphology and EDX analysis verified the elemental composition and distribution. Under ultraviolet (UV) irradiation, the nanocomposite exhibited remarkable photocatalytic degradation efficiency (~97%) for both MB and CV. Key operational parameters were systematically evaluated, including pH (2–10), catalyst dosage (0.005–0.04 g/20 mL), and initial dye concentration (10–20 ppm). Optimal performance was achieved at pH 10, with a catalyst dosage of 0.03–0.04 g/20 mL and lower dye concentrations. The enhanced photocatalytic activity can be attributed to the synergistic effects coming from GO’s electron transport capabilities, ZnO’s strong photocatalytic activity and lignin’s additional degradation sites. Furthermore, the nanocomposite demonstrated excellent reusability, retaining nearly 60% of its degradation capacity after four cycles, outperforming its individual components. These results highlight the potential of this composite material for sustainable wastewater treatment applications. Full article

Developing high-performance bio-based epoxy resins as sustainable alternatives to petroleum-derived bisphenol A (BPA) epoxies for recyclable carbon fiber-reinforced polymers (CFRPs) is pivotal in materials research. Herein, the bio-based bisphenol monomer BDEF was synthesized from the lignin derivative 4-propylguaiacol. The derived epoxy monomer BDEF-EP was cured with adipic acid to form a bio-based vitrimer. Stress relaxation synergistically accelerates through intrinsic dynamic carboxylic acid ester exchange and enhanced chain mobility from the flexible propyl structure. At 220 °C, this vitrimer shows rapid stress relaxation (τ* < 30 s) and repairs ~90% of surface scratches in 30 min. It exhibits tensile and flexural strengths of 69 MPa and 105 MPa, respectively. BDEF-EP’s low viscosity reduces diluent needs in composite fabrication, lowering costs and improving efficiency. The resulting bio-based CFRP achieves tensile and flexural strengths of 543 MPa and 414 MPa, respectively, which are comparable to commercially available petroleum-derived CFRP. In addition, CFRP containing dynamic crosslinked networks demonstrates degradable recyclability in ethylene glycol solvent, preserving the surface morphology and chemical structure of recovered carbon fibers. The results demonstrate that this bio-based epoxy vitrimer has promising potential for developing sustainable, degradable, and recyclable CFRP composites. Full article

Nitrile rubber (NBR) exhibits excellent oil resistance, wear resistance, gas barrier properties, and mechanical properties. On the other hand, lignin, a by-product of the pulp and paper industry, can serve as an ideal substitute for carbon black as a reinforcing agent for rubber. However, when NBR is directly compounded with lignin, direct compounding fails to achieve the desired reinforcing effect due to poor dispersion of lignin in the NBR matrix and poor compatibility with the NBR phase. In this paper, carboxyl groups were introduced via cyano group hydrolysis. By controlling the hydrolysis time, we successfully prepared two types of carboxylated NBR with different carboxyl contents. Subsequently, the carboxylated NBR was processed into lignin/NBR composites via dry blending. The results indicated that the introduction of carboxyl groups endowed NBR with higher polarity and reactivity, significantly enhancing the interfacial compatibility between lignin and the rubber matrix. The mechanical properties of the composite were greatly improved, with the mechanical strength increasing from 4.5 MPa without carboxyl groups to 13.8 MPa with high carboxyl content. The good dispersion of lignin also significantly improved the thermal stability of the composite. The carboxylation modification strategy of NBR provides a new approach for preparing high-performance NBR/biomass composites. Full article

To address the inherent challenge of poor interfacial compatibility in lignin/poly(butylene adipate-co-terephthalate) (PBAT) composites, lignin was extracted from Camellia oleifera shells and subjected to sequential solvent fractionation using ethanol, acetone, and tetrahydrofuran (THF). Two representative fractions—acetone-soluble (ACL) and THF-soluble (THFL)—were selected for composite preparation with PBAT via solvent casting. The influence of lignin fractionation on the structural and performance characteristics of the resulting composites was systematically evaluated through Fourier-transform infrared (FTIR) spectroscopy, the water contact angle (WCA), differential scanning calorimetry (DSC), tensile testing, and scanning electron microscopy (SEM). The results revealed that the abundant hydroxyl groups and benzene rings present in both ACL and THFL facilitated hydrogen bonding and conjugation interactions with the PBAT matrix, significantly improving interfacial adhesion. Notably, the ACL fraction effectively suppressed phase separation and increased the glass transition temperature (T_g) by 1.9 °C, leading to a 13.9% enhancement in tensile strength compared to neat PBAT. More strikingly, the incorporation of only 7 wt% THFL resulted in a remarkable 31% improvement in tensile strength. This substantial enhancement was primarily attributed to the favorable polarity match between THFL and PBAT, as well as the nucleating effect of THFL, which increased the crystallinity of PBAT by 25.3%. This study highlights the effectiveness of sequential lignin fractionation in tailoring the interfacial properties of biodegradable polymer composites. It also provides a promising strategy for the high-value utilization of lignin toward the development of high-performance, environmentally friendly materials. Full article

In this study, we developed a combination strategy of bioenzymes and sophorolipid (SL) co-pretreatment to enhance volatile fatty acids (VFAs) in co-fermentation of waste activated sludge (WAS) and rubberwood hydrolysates (RWHs). Among all the pretreatments, SL and laccase co-pretreatment markedly increased soluble bioavailable substrates (carbohydrates and proteins) by inducing EPS catabolism and WAS disintegration, and obtained the highest VFAs yield of 7049.43 mg/L. The proportion of VFA composition can be controlled by modifying the types and amounts of added bioenzymes. Under SL and laccase co-pretreatment conditions, RWHs were more efficiently converted into VFAs due to the higher activity of WAS, resulting in lower cellulose (3.41%) and lignin (0.66%) content in the fermentation broth. Compared with other pretreatments, SL and laccase co-pretreatment enhanced the enrichment of the functional microorganisms, including anaerobic fermentation bacteria (Firmicutes, Bacteroidota, and Proteobacteria) and reducing bacteria (Acinerobacter and Ahniella). Therefore, the combination pretreatments might be a promising solution for strengthening VFA accumulation in the WAS and RWH co-fermentation. Full article

Empty pinecones are a largely available byproduct of Pinus pinea L. nut production, mostly concentrated in the Mediterranean area; e.g., in Portugal, around 70,000 tons of pinecones are produced annually. One valorization line for residual biomass is its use as biosorbents for the removal of contaminants in effluents and water courses which are an increasing environmental problem. This study explores the biosorbent potential of pinecones to remove zinc ions from aqueous solutions. We analyzed the morphology and chemical composition of pinecones (9.4% extractives, 37.0% lignin, 68.6% holocellulose, 1.4% ash). The effect of pH and adsorbent dose on the adsorption process was studied, as were the sorption kinetics and isotherms. The pinecones showed good potential to remove Zn ions, with 96% removal at pH 7 and a maximum adsorption capacity of 7.92 mg g⁻¹. The process followed the Freundlich isotherm model, indicating a heterogeneous surface and multilayer adsorption, and the pseudo-second-order kinetic model, suggesting chemisorption as the dominant mechanism. The use of pinecones as bio-adsorbent is therefore a green and low-cost alternative for environmental remediation and biomass waste management. Full article

This study aimed to develop an effective method to overcome the challenge of straw return in cold-region soil. We systematically investigated the synergistic mechanism of montmorillonite (MMT) and composite amino acid (CAA) on straw humification and carbon sequestration through a low-temperature litterbag field experiment. The results indicate that the combined treatment (MMT-CAA) significantly increased the decomposition rate of straw by 42.1% compared to the control (CK), with MMT showing particular efficacy in lignin degradation (28.3% reduction), while the CAA preferentially decomposed cellulose (19.7% reduction). An FTIR analysis of the decomposition products confirmed these findings. Water-soluble organic carbon (WEOC) and its three-dimensional fluorescence spectra exhibited a 25.0% increase in MMT-CAA and enhanced aromaticity of humic acid-like substances. Humic substances and their ¹³C-NMR revealed that MMT-CAA enhanced humic acid formation and molecular stability by 31.4% (with a 47.8% increase in aromaticity). A further redundancy analysis and symbiotic network of microorganisms demonstrated that MMT-CAA increased the abundance of lignocellulose-degrading phyla (Actinomycetes and Stramenomycetes) and the formation of a complex co-degradation network. Field corn planting trials indicated that MMT-CAA increased plant height by 55.1%, stem thickness by 58.7%, leaf area by 70.2%, and the SPAD value by 41.1%. Additionally, MMT significantly reduced CO₂ and N₂O emission fluxes by 35.6% and 15.8%, respectively, while MMT-CAA increased CH₄ uptake fluxes by 13.4%. This study presents an innovative strategy, providing mechanistic insights and practical solutions to synergistically address the challenges of slow straw decomposition and carbon loss in cold regions. Full article

Packaging demand currently exceeds 144 Mt per year, of which >90% is conventional plastic, generating over 100 Mt of waste and 1.8 Gt CO₂-eq emissions annually. In this review, we systematically survey three classes of lignocellulosic feedstocks, agricultural residues, fruit and vegetable by-products, and forestry wastes, with respect to their physicochemical composition (cellulose crystallinity, hemicellulose ratio, and lignin content) and key processing pathways. We then examine fabrication routes (solvent casting, extrusion, and compression molding) and quantify how compositional variables translate into film performance: tensile strength, elongation at break (4–10%), water vapor transmission rate, thermal stability, and biodegradation kinetics. Highlighted case studies include the reinforcement of poly(vinyl alcohol) (PVA) with 7 wt% oxidized nanocellulose, yielding a >90% increase in tensile strength and a 50% reduction in water vapor transmission rate (WVTR), as well as pilot-scale extrusion of rice straw/polylactic acid (PLA) blends. We also assess techno-economic metrics and life-cycle impacts. Finally, we identify four priority research directions: harmonizing pretreatment protocols to reduce batch variability, scaling up nanocellulose extraction and film casting, improving marine-environment biodegradation, and integrating circular economy supply chains through regional collaboration and policy frameworks. Full article

This study explores the potential application of lignin nanoparticles and chitosan–lignin nanoparticles (CLNs) as hydrophobic barrier coatings for paperboard. The lignin nanoparticles were initially prepared using a mixed solvent of ethanol and acetone. Their characteristics were examined via scanning electron microscopy (SEM) and dynamic light scattering, which revealed particle sizes in the range of 180–400 nm. The results indicated that the coatings with pure lignin nanoparticles failed to impart hydrophobicity to the paperboard, whereas the CLN coatings significantly enhanced hydrophobicity and reduced water absorption. The water contact angle increased from 109° to over 128° after the first CLN coating, remained at 127° with the second and third coating layers, and was maintained at 119° with four layers. Multilayer coatings were applied to improve barrier performance; however, no further enhancement in hydrophobicity was observed. The CLN-coated paper exhibited a significantly improved surface smoothness, as confirmed by SEM. The results indicate that a single-layer CLN coating is effective for imparting water-barrier properties to paperboard. In contrast, the coating with pure lignin nanoparticles resulted in cracked surfaces and inconsistent coating thicknesses. Full article

In this study, alkali-treated wood flour/dynamic polyurethane composites were successfully prepared through a solvent-free one-pot method and in situ polymerization. The effects of the alkaline treatment process, changes in the flexible long-chain content in the dynamic polyurethane system, and the wood flour filling amount on the interface’s bonding, mechanical, and reprocessing properties were investigated. Partial removal of lignin and hemicellulose from the alkali-treated wood flour enhanced rigidity and improved interface bonding and mechanical strength when combined with dynamic polyurethane. The tensile strength was improved from 5.65–11.00 MPa to 13.08–23.53 MPa. As the composite matrix, dynamic polyurethane could not easily infiltrate all wood flour particles when its content was low or its fluidity was poor. Conversely, excessive content or overly high fluidity led to leakage and the formation of large pores, affecting the mechanical strength. As the polyol content increased, the matrix exhibited greater fluidity, which enabled it to accommodate more wood flour and penetrate the cell cavity or even the cell wall. This improved infiltration enhanced the interface bonding performance of the composites and made their mechanical properties sensitive to changes in wood flour content. The reprocessing ability of the prepared composites decreased with the increase in wood flour content, and the interface bonding was enhanced after reprocessing. The tensile strength retention rate of the composites prepared with alkali-treated wood flour was lower. This study provides a theoretical basis for optimizing the performance of wood fiber/dynamic polyurethane composites and an exploration path for developing self-healing and recyclable wood–plastic composites, which can be applied to building materials, automotive interiors, furniture manufacturing, and other fields. Full article

The increasing frequency of wildfires in larch forests across the discontinuous permafrost zone of Eastern Eurasia heightens the vulnerability of soil organic matter (SOM) under a warming climate. However, post-fire SOM thermal stability in this frequently burned forest region remain poorly understood. We assessed the long-term effects of wildfire on SOM structure and thermal stability in burned and unburned larch forests using complex analytical approaches: pyrolysis–gas chromatography/mass spectrometry (TMAH-py-GC/MS) and thermogravimetry/differential thermal analysis (TG/DTA). The focus was on the upper mineral soil horizon, where fire impacts may persist for decades. Sixteen years post-fire, total carbon content did not differ significantly between burned and control soils. Nonetheless, the molecular composition and thermal properties of SOM showed marked post-fire alterations. Burned soils exhibited higher proportions of lignin-derived compounds and reduced levels of short-chain fatty acid methyl esters. A lower degradation temperature (T50) and a higher thermal mass loss of labile fractions indicate a decrease in the thermal stability of SOM after fire. Our study shows that recurrent forest fires in larch forests of the Russian Far East decrease the thermal stability of soil organic matter, thereby increasing its vulnerability to subsequent fire degradation. Full article

Natural rubber (NR) possesses excellent comprehensive properties and plays an irreplaceable role in both national defense and people’s livelihood. In recent years, lignin, as a new development trend, has emerged as a reinforcing filler in natural rubber, partially replacing traditional carbon black, or serving as an antioxidant in rubber. However, lignin, a polar biomass filler, exhibits poor compatibility with non-polar natural rubber. To address the compatibility issue between the two, this paper adopts an in situ method, utilizing formic acid and hydrogen peroxide to modify natural rubber into two types of epoxidized natural rubber (ENR) with different degrees of epoxidation (E-25% and E-45%). Subsequently, through wet mixing, it is combined with a lignin aqueous solution (20 parts), and ethanol is used as a flocculant to prepare lignin/ENR composite rubber materials. Comprehensive characterization of the composite rubber materials reveals that after epoxidation modification, the interfacial compatibility between lignin and natural rubber has been significantly improved. Wet mixing also effectively enhances the dispersibility of lignin in the rubber matrix. Compared to natural rubber, the composite material with an epoxidation degree of 25% exhibits significantly superior mechanical properties and thermal stability. The tensile properties of the composite rubber increase from 29.4 MPa to 36.2 MPa, indicating the significant reinforcing effect of lignin. This study aims to investigate the effects of the epoxidation degree (25% and 45%) of epoxidized natural rubber (ENR) and the mixing method on the compatibility and reinforcement performance of composite rubber, providing a new method for preparing high-performance lignin/ENR composites. Full article