Search Results (183)

Conventional biochar-based solid base catalysts often suffer from cumbersome preparation procedures and pore blockage during the loading of active components. To overcome these limitations, we developed an in situ construction strategy to fabricate hierarchically porous solid-base catalysts via cross-linking and carbonization of alkali lignin. Using alkali lignin as the carbon precursor, a soft-template-assisted cross-linking system enables the simultaneous formation of a hierarchical carbon framework and in situ generation of basic active sites through one-step pyrolysis under alkaline conditions. The physicochemical properties of the catalysts, including specific surface area, pore structure, and surface basicity, are effectively tuned by adjusting the carbonization temperature (600–800 °C). The optimized catalyst, KLPF-800, exhibits a high specific surface area of 309 m²·g⁻¹ and a well-developed hierarchical pore architecture, delivering excellent catalytic performance in aqueous-phase glucose isomerization. A fructose yield of 33.21% is achieved at 120 °C within 20 min. This work provides a feasible strategy for valorizing lignin and designing efficient heterogeneous base catalysts. Full article

Arundo donax L. is a significant energy crop and perennial grass, with its efficient conversion holding substantial implications for the utilization of agricultural biomass resources. However, the distinct effects of acid and alkali pretreatments on its lignocellulose degradation patterns and structural modifications remain inadequately characterized. This study utilized Arundo donax L. as raw material to compare the effects of dilute sulfuric acid and sodium hydroxide pretreatments on its component degradation and structural modifications. Single-factor experiments were conducted, and the mechanisms were investigated using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and scanning electron microscopy (SEM) analyses. The results indicated that dilute sulfuric acid pretreatment primarily degraded hemicellulose (up to 85.8%) with limited lignin removal (<13%), whereas sodium hydroxide pretreatment effectively removed lignin (66.8%). XRD analysis revealed that crystallinity after dilute acid treatment was significantly higher than that of untreated samples (p < 0.05). Sodium hydroxide treatment induced a concentration-dependent non-monotonic change in crystallinity: the crystallinity index (CrI) peaked at a 1% concentration, was significantly lower at 3% and 4%, and showed intermediate values at 2% and 5%. The apparent crystallite size remained at 3.0–3.3 nm, suggesting that both pretreatments primarily targeted amorphous regions. FTIR analysis confirmed that alkali treatment more thoroughly disrupted ester bonds and lignin. SEM images revealed that alkali-treated fiber bundles were more loosely packed with relatively smoother surfaces. In acid treatment, 100 °C was identified as the critical temperature for a significant increase in crystallinity, whereas in alkali treatment, temperature had no significant effect on crystallinity. Full article

The efficient utilization of hardwood lignocellulosic biomass has attracted increasing attention as a sustainable strategy for the high-value conversion of renewable resources. Chemical-mechanical pulping (CMP) is a promising route for hardwood utilization; however, its performance is strongly influenced by species-dependent differences in chemical composition, macromolecular structure, and physical accessibility. In this study, four representative hardwood species (poplar, sycamore, eucalyptus, and acacia) were selected as model feedstocks to investigate the relationships between structural characteristics and CMP performance in alkali-assisted systems. The chemical composition and structural features of cellulose, hemicellulose, lignin, and lignin-carbohydrate complexes were characterized, together with key physical parameters including density, porosity, and fiber morphology. The effects of alkali charge on fiber softening, fibrillation development, and paper properties were then evaluated. The results revealed pronounced species-dependent differences in alkali response, which were closely correlated with variations in cellulose supramolecular organization, hemicellulose substitution characteristics, lignin structural features, lignin-carbohydrate associations, and wood microstructure. This study provides a comprehensive qualitative comparative analysis of the relationships between wood structural features and CMP performance. Hardwoods with lower density and higher porosity exhibited more efficient alkali penetration and superior performance under mild conditions, whereas denser species such as sycamore and eucalyptus required higher alkali charge. This work provides important insights into the structure-performance relationships governing alkali-assisted CMP behavior, and offers useful guidance for the efficient utilization of lignocellulosic biomass in pulp and paper applications. Full article

This study elucidates the mechanism enabling the low-voltage electrolysis of black liquor (BL) for integrated resource recovery. The process simultaneously generates protons at the anode via the oxidation of organics (OOR), which occurs at a lower potential than the oxygen evolution reaction (OER), and induces lignin precipitation. Concurrently, hydrogen and hydroxide ions are produced at the cathode through the hydrogen evolution reaction (HER). Driven by the electric field, sodium ions migrate from the anode to the cathode chamber, combining with hydroxide ions to form sodium hydroxide, thereby achieving the synchronous production of acid, alkali, hydrogen, and modified lignin in a single process. Using a platinum electrode, we conducted a mechanistic investigation through linear sweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and detailed product analysis. The results show that overall efficiency is controlled by competition at the anode between OOR and OER, which directly determines proton yield. A critical trade-off exists between anodic proton generation and cathodic alkali recovery, driven by the competitive migration of protons and sodium ions across the cation-exchange membrane. The proton yield was highly dependent on the initial BL composition, with a characteristic peak observed under specific conditions. Conversely, the sodium hydroxide recovery rate was maximized when the anolyte pH remained high, minimizing competitive proton migration. This work provides fundamental insights into the interfacial mechanisms of BL electrocatalytic, establishing it as a versatile electrochemical biorefinery platform for simultaneous proton and alkali production from a renewable waste stream, beyond its role as a hydrogen source and lignin recovery. Full article

Waste sweet potato vine fiber (WSVF) effectively extends asphalt service life by enhancing cracking resistance in gel-like base asphalt matrices, yet its crack-resistant mechanism lacks mechanical characterization. This study proposes an analytical method for evaluating WSVF-modified asphalt’s crack-resistant behavior based on the principle of mechanical energy balance. First, alkali-treated WSVF with a mass fraction of 1% was added into 70# gel-like base asphalt to prepare WSVF-modified asphalt. Lignin fiber (LF)-modified asphalt and 70# gel-like base asphalt were selected as control groups, and three types of time sweep and scanning electron microscopy tests were conducted. Then, the three-dimensional cracking volume model and damage kinetics model were established for analyzing the cracking response behavior, defining the asphalt damage variable and determining the cracking damage activation energy (E_acd). Finally, the E_acd was used to quantify the difficulty of the cracking damage process for the WSVF-modified asphalt. The reinforcement and cracking resistance mechanisms of WSVF in asphalt were analyzed by the E_acd and asphalt microstructure. The results show that the cracking volume response of WSVF-modified asphalt under cyclic loading presents three-stage nonlinear behaviors. The established fatigue damage kinetics model can accurately describe the fatigue damage evolution process of alkali-treated WSVF-modified asphalt. The E_acd values of WSVF-modified asphalt, LF-modified asphalt, and 70# gel-like base asphalt are 10.60 kJ·mol⁻¹, 21.83 kJ·mol⁻¹, and 29.74 kJ·mol⁻¹, respectively. After alkali treatment, the WSVF surface exhibits grooves, demonstrating superior adsorption and storage capacity for asphalt. The WSVF can cross link through the bonding effect of asphalt and form a three-dimensional network framework structure, which can significantly increase the E_acd and provide strengthening and toughening effects on gel-like base asphalt. In summary, E_acd values are used as a mechanical indicator to quantitatively evaluate the fatigue cracking resistance of WSVF-modified asphalt. Full article

The impact of pretreatment methods on the fermentation quality and nutritional profile of bamboo silage was assessed to determine the optimal ensiling strategy. Tender bamboo underwent microwave, ultrasound, alkali, and irradiation pretreatments. Subsequently, a four-factor, three-level L9 (3⁴) orthogonal experiment was employed, utilizing pretreated bamboo as the substrate. The experiment evaluated the effects of silage time (30, 45, 60 days), moisture content (55%, 60%, 65%), cellulase addition [2, 4, and 6 mg/g FM (Fresh weight)], and silage inoculant addition (0.5, 5, 50 mg/g FM). Results indicated that γ-ray irradiation pretreatment effectively reduced lignin and cellulose content while increasing reducing sugars levels approximately fourfold compared to the control group. Six out of the nine treatment groups exhibited superior comprehensive fermentation quality scores, with silage time demonstrating the most significant influence on the fermentation quality of tender bamboo silage. The order of influence was silage time > silage inoculant level > moisture content > cellulase, with a silage time of 30 days, a silage inoculant level of 0.5 mg/g FM, a moisture content of 65%, and a cellulase level of 2 mg/g FM, all contributing to enhanced fermentation quality. Regarding nutritional composition, silage time significantly impacted crude protein and soluble sugar levels, with optimal levels observed at 30 and 60 days, respectively. Moisture content primarily affected soluble sugar levels, followed by neutral detergent fiber, with an optimal level of 55%. Other factors showed minimal effects. Based on fermentation quality and nutritional component analysis, and prioritizing fermentation quality while considering cost-effectiveness, the optimal ensiling conditions for bamboo were determined to be a silage time of 30 days, a moisture content of 65%, an addition of 2 mg/g FM of cellulase, and an addition of 0.5 mg/g FM of silage inoculant. Full article

Against the backdrop of the continuous advancement of high-quality development in road infrastructure and the growing demand for waste asphalt recycling, the application limitations of traditional petroleum-based asphalt rejuvenators have become increasingly prominent due to their high resource dependence, poor compatibility with aged asphalt, and high volatility. By contrast, bio-oil, characterized by wide feedstock availability, outstanding renewability, and the inherent potential to modulate the colloidal structure and properties of aged asphalt, has gradually emerged as a critical research direction in the field of asphalt rejuvenator development. This paper provides a comprehensive review on the research, development and engineering application of bio-based rejuvenators. Firstly, the main feedstock systems, including vegetable oils, lignin derivatives and algal oils, are introduced, and the core preparation technologies (e.g., pyrolysis and alkali-catalyzed transesterification) are discussed, along with the impacts of their key process parameters on the chemical composition and storage stability of the end products. Subsequently, the performance of various bio-based rejuvenators in optimizing the rheological properties, high- and low-temperature performance, as well as fatigue and cracking resistance of aged asphalt is summarized, and the underlying rejuvenation mechanisms are generalized. Finally, the prevailing technical bottlenecks, such as inconsistent quality of as-prepared products and insufficient understanding of the long-term aging mechanism, are analyzed. Future research directions including oriented molecular modification, interfacial regulation, and full life cycle assessment (LCA) are proposed, to provide a systematic reference for their large-scale engineering application. Full article

As a representative intangible cultural heritage of Tibet, China, Nyemo Xuelai Tibetan paper has maintained its millennium-old inheritance, relying on its unique surface properties and aging resistance. However, at present, there remains a research gap regarding the surface characteristics of Nimu Xuela Tibetan paper and their correlation with aging mechanisms. To reveal their intrinsic mechanisms and provide scientific protection schemes, this study systematically analyzed the surface microstructure, chemical composition, pH variation, and aging resistance of 7 groups of Xuelai Tibetan paper samples using SEM-EDS, ATR-FTIR, pH testing, and dry-heat aging experiments (105 °C, 144 h). Combined with traditional crafts, the formation mechanism of properties was clarified, and multi-dimensional protection strategies were proposed. The results show that aging time exerted a highly significant effect on the D65 brightness, pH value, and tensile index of Xuelai Tibetan paper (p < 0.001). The fibers of Xuelai Tibetan paper are flat and ribbon-like, with an aspect ratio of 50–80, forming a tightly intertwined network structure. The core chemical component is cellulose with a relatively low lignin content, and the elemental composition is dominated by carbon and oxygen. Some samples contain calcium-based substances (0%–1.79%) derived from salt lake alkali. After aging, the D65 blue light diffuse reflectance factor (abbreviated as D65 brightness) retention rate of the samples ranges from 84.81% to 92.21%, and the tensile strength retention rate ranges from 30.78% to 90.00%. Calcium-based substances can inhibit the hydrolysis of cellulose glycosidic bonds through a weak alkaline buffering effect, improving aging-resistance stability. The excellent performance of Tibetan paper originates from the synergistic effect of traditional crafts: Stellera chamaejasme as raw material provides the material basis of high cellulose and long fibers; alkaline cooking removes lignin and retains the buffering components; manual beating optimizes the fiber’s interweaving structure; and natural air-drying ensures surface uniformity. Based on this, a multi-dimensional strategy of preventive protection and living inheritance is proposed: cultural relic protection focuses on pH stabilization, controlled storage, and non-destructive cleaning, and craft inheritance achieves sustainable development through raw material standardization, process refinement, and digital training. This study establishes the craft–characteristic–performance correlation mechanism of Xuelai Tibetan paper, verifying the statistical significance of aging-induced property changes and providing a scientific basis for the protection and inheritance of traditional handmade paper. Full article

Rapeseed stalks (Brassica napus), an abundant agricultural residue, represent a promising non-woody raw material for the pulp and paper industry. This study focuses on the chemical and structural characterization of alkali lignins isolated from black liquors generated by two common delignification methods: Kraft and Soda-Anthraquinone Pulping of rapeseed stalks. The objective is to understand how the chemical environment of each process influences the final structure, fragmentation degree, and reactivity of the isolated lignin. In practice, lignin samples are recovered from black liquors produced under varying conditions (alkali charge, time, and temperature) to achieve defined levels of delignification. Detailed characterization was performed using advanced analytical techniques, including Gel Permeation Chromatography, Solid-State Cross-Polarization/Magic-Angle-Spinning Nuclear Magnetic Resonance, and FT-IR and UV-Vis Spectroscopy. The findings provide essential data on the structural differences, confirming the suitability of the resulting materials for potential high-value applications. Furthermore, the structural similarities and performance indicators suggest that the Soda-AQ process enables successful delignification of rapeseed stalks without the sulfur emission issues associated with the Kraft method, thus validating the former as an environmentally cleaner alternative for non-wood biomass utilization supporting the complete valorization of rapeseed agricultural waste. Full article

This research investigates the potential of secondary lavender biomass (Lavandula officinalis) as a raw material for paper production within the context of the circular economy and its practical applications. Lavender stems, a by-product of essential oil extraction, were processed using the nitrate–alkali pulping method. The chemical composition of the raw material was analysed according to TAPPI standards, and the resulting pulp was characterised in terms of its mechanical and physical properties, including tensile strength and air permeability. Lavender stems contained 29.43% cellulose and 24.10% lignin, indicating moderate delignification efficiency under the applied conditions. The pulp yield was 24.2% with a Kappa number of 15.9. Of the prepared sheets, the paper with a weight of 80 g·m⁻² showed the best mechanical properties, with a breaking length of 1.71 km and a tensile strength index of 16.76 N·m·g⁻¹. In addition, lavender-based paper demonstrated measurable repellent activity against Tineola bisselliella, reducing insect presence by 70% compared to control samples, as determined by controlled laboratory exposure tests. This bioactivity is attributed to residual volatile compounds such as linalool and linalyl acetate, originating from lavender biomass. Overall, lavender secondary biomass represents a promising non-wood fibre for the production of biodegradable, functional paper materials that combine structural integrity with natural repellent properties. Full article

The development of high-performance wood-based materials has attracted increasing interest as a means of enhancing the mechanical properties of wood for structural applications. Mechanical densification combined with chemical pretreatment is an effective approach; however, many reported methods rely on complex multi-component chemical systems or severe chemical conditions designed to dissolve lignin or hemicelluloses. In this study, a simplified NaOH-only pretreatment followed by hot-press densification was investigated, targeting selective cell-wall plasticization rather than extensive polymer dissolution. Juniper (Juniperus communis), hawthorn (Crataegus monogyna), and birch (Betula pendula) were used as samples of softwood and hardwood species. Wood specimens were pretreated in 1 M NaOH at 145 °C for 10–30 min and subsequently densified by radial compression. Changes in chemical composition were evaluated by HPLC after acid hydrolysis and FTIR spectroscopy, while microstructural changes were examined using SEM. Physical and mechanical properties were assessed through density measurements and three-point bending tests. The results show that NaOH-only pretreatment induces hemicellulose deacetylation and modification of interpolymer linkages without substantial changes in the main wood polymer contents. Densification resulted in effective lumen collapse and a compact microstructure, leading to a significant increase in density and mechanical properties. Overall, the results demonstrate that efficient wood densification and mechanical enhancement can be achieved by promoting polymer mobility through selective cleavage of interpolymer bonds, using a simplified, single-alkali pretreatment that reduces chemical complexity and material loss while avoiding extensive lignin or hemicellulose dissolution. Full article

In order to improve the utilization of alkali lignin (AL) as an effective component for ultraviolet (UV) shielding, demethylation and acetylation modification were carried out to improve the UV absorption performance of lignin. Then, lignin-based sunscreens were successfully prepared by mixing the modified lignin and commercial cream without UV shielding ingredients. The modified alkali lignin was comprehensively characterized in terms of its molecular weight, functional groups and structural properties by GPC, UV spectroscopy and ³¹P NMR. The results showed that the Mw of all three lignin feedstocks (AL, AL_MeOH and AL_Acetone) was decreased with prolonged demethylation time. Compared to the original feedstock, demethylated AL had a darker color and improved UV absorption performance due to the increased phenolic hydroxyl content (approximately 4.35 mmol/g). ³¹P-NMR spectra showed that the guaiacyl phenolic hydroxyl content decreased rapidly after acetylation, causing the sample color to become lighter. Among all lignin-based sunscreens, DAL_Acetone achieved the highest SPF value of 11.23, a 69.4% increase over its pre-reaction level and a 7.58-fold enhancement compared to the original lignin. In summary, this study opens a promising avenue for repurposing industrial lignin as a sustainable biomaterial in high-value sectors like UV-blocking agents and cosmetic formulations. Full article

Developing sustainable, high-performance biomass composites is crucial for replacing non-renewable structural materials. In this study, a “bamboo steel” composite was fabricated using a multilevel modification strategy involving alkali pretreatment, toughened resin impregnation, and surface functionalization. Bamboo fibers were treated to remove hemicellulose and lignin, enhancing porosity and interfacial bonding. The bamboo scaffold was subsequently impregnated with a thermo-plastic polyurethane-modified epoxy resin to create a robust, interpenetrating network. The optimized composite (treated at 80 °C) exhibited a flexural strength of 443.97 MPa and a tensile strength of 324.14 MPa, demonstrating exceptional stiffness and toughness. Furthermore, a superhydrophobic coating incorporating silica nanoparticles was applied, achieving a water contact angle exceeding 150° and excellent self-cleaning properties. This work presents a scalable strategy for producing bio-based structural materials that balance mechanical strength with environmental durability. Full article

Wood is an attractive renewable material, yet its mechanical performance, dimensional stability, and moisture sensitivity limit its use in structural applications. Conventional densification methods often rely on aggressive alkali solutions or resin impregnation, generating environmental concerns and causing excessive cell-wall degradation. In this study a sustainable hydrothermal densification process for oak wood using only a water–ethanol solution in a sealed Teflon-lined autoclave has been investigated and implemented. Treatment at 195 °C for 80 min selectively degraded hemicelluloses and partially reorganized lignin without compromising the cellulose network, followed by hot-pressing at 100 °C under 5 MPa. The hydrothermally densified oak exhibited a significant improvement in stiffness, with a 125% increase in storage modulus relative to untreated wood and a 19.6% enhancement compared to alkali-treated samples. The findings demonstrated that hydrothermal processing is an efficient, low-impact alternative for producing high-performance densified wood suitable for sustainable construction and composite applications. Full article

The development of novel materials from biomass is a potential alternative to replace traditional petrochemical resources. In accordance with the “Bamboo Substitute Plastic” initiative, bamboo-based lightweight porous materials are a class of foam materials fully prepared from biomass resources with a lightweight and high-strength structure. However, issues such as excessive lignin content and uneven pore structure distribution within these materials hinder their application. This study utilized bamboo powder as a raw material to prepare lightweight, porous molding materials through a hydrothermal grinding process. The influence of different concentrations of alkaline pretreatment was investigated. The fabricated molding material had a density of 0.36–0.49 g/cm³ at 80 °C and 0.32–0.38 g/cm³ at 105 °C. Samples dried at 80 °C had a water absorption of 161% to 304%, while those dried at 105 °C had a water absorption of 223% to 305%. The wet swelling was characterized by volume expansion from 6.2% to 7.7%. The surface of the molding materials became increasingly homogeneous without any cracks due to the alkali pretreatment. FTIR data showed that more surface hydroxyl groups were observed after alkaline pretreatment, and some carbonyl groups in the hemicellulose structure were removed; meanwhile, the crystallinity index after alkaline pretreatment was higher than that of untreated bamboo. The alkali solution was proposed to remove part of the lignin and improve the fibrillation degree of the bamboo fibers. The highest tensile strength of the samples was 9.63 MPa, while the highest compressive strength obtained was 0.92 MPa under the alkali treatment. With lightweight and fully degradable properties, the bamboo-based porous molding materials have promising application prospects in environmental protection, construction, packaging, and related fields. Full article