Search Results (4,325)

This research proposes an approach based on a circular economy principle for the integral valorization of Sargassum from the Mexican Caribbean. The biomass was characterized through proximal and elemental analyses, and then an oxidative pretreatment was carried out to enhance a sequential processing scheme to extract sodium alginate and use the solid waste as a substrate for biogas production via anaerobic digestion. The oxidative pretreatment successfully reduces the recalcitrant content and the concentration of heavy metals. The sodium alginate extracted from treated biomass achieves a yield higher than 20%; the characterization of the polymer via nuclear magnetic resonance showed that the mannuronic-to-guluronic ratio was between 0.34 and 0.62, indicating the potential for its use for environmental and biomedical applications. The highest yield in methane production was 328 mL CH₄/g of volatile solids, with a purity of 90%, and was achieved using the waste from alginate extraction with an inoculum-to-substrate ratio of 1:1. The experimental data presented an excellent fit to a Gompertz model (R² > 0.99). The proposed valorization pathway improves the sustainability of Sargassum management, prioritizing the recovery of high-value compounds before energy production. This circular approach provides a framework for converting environmental challenges into opportunities in the Caribbean. Full article

Activated carbon is a highly porous adsorbent material that is often used to treat wastewater using physical and chemical adsorption. Agricultural and urban biomass waste valorization to activated carbon is a low-cost, renewable solution to commercial adsorbents, and can help prevent waste from tree pruning from being dumped in landfills or openly burned. In this study, the ability of the ground and unground Ficus nitida leaves to efficiently adsorb Rhodamine B dye and total chromium from model aqueous solutions was investigated. Chemical activation was performed using phosphoric acid (H₃PO₄) at different impregnation ratios (1:1, 2:1, and 4:1). Samples obtained as a result of the above activation were labeled G1–G3 (ground) and UG1–UG3 (unground). The adsorption test showed that the samples with the highest activation ratio (G3 and UG3) gave the best results, removing 92% and 94% RhB, respectively, in 20 minutes. After 24 h, sample G3 showed the best efficiency of 73.31% (13.35 ppm remaining) in chromium removal, where the adsorption kinetics were well described by the pseudo-second-order model (R² > 0.98), indicating that there may be some chemical interactions occurring during the adsorption process along with physisorption, and the RhB adsorption isotherms for sample UG3 were well described by the Langmuir isotherm (R² > 0.95). The higher activation ratio and grinding increased the carbon content (up to 90% C for G3), surface functional groups, and textural properties (BET surface area of 699 m²/g and total pore volume of 3.06 cm³/g). Furthermore, reusability tests over five consecutive cycles demonstrated the excellent recyclability of sample G3, retaining removal efficiencies of 80.5% for RhB and 50.2% for total chromium. The results revealed that Ficus nitida leaf-based AC can be used as an efficient, economical, and reusable adsorbent material for sustainable environmental cleanup and water purification systems and will create a circular economy for waste management. Full article

In recent years, in the presence of environmental pollution, green materials have emerged as a research hotspot. The value-engineered design of electron nanocatalysts using low-cost biomaterials has demonstrated special electrocatalytic efficiency and performance in methanol oxidation reactions within direct methanol fuel cells (DMFCs). These electro/nanocatalysts were successfully heat-treated in a study involving multiple temperature controls and activation. The research involved studying samples C-400, C-600, and C-800, which were carbonized at temperatures of 400, 600, and 800 °C from snail shells. Next, these samples were activated using potassium hydroxide, resulting in samples AC-400, AC-600, and AC-800. Moreover, the ability of the resulting electron nanocatalysts, as heat-treated catalysts, to enhance the electrocatalytic efficiency of methanol oxidation reactions, along with the significant effects of temperature variations before and after activation, was investigated. The surface area of the sample increased successfully from 4.6691 m²/g to 14.1763 m²/g after activation, while the pore volume increased from 0.02225 m³/g to 0.07233 m³/g. The results clearly show that methanol oxidation reactions were more efficient and active on the surface of the electron nanocatalyst at 800 °C (AC-800). The current density successfully increased from 22.76 mA/cm² to 49.89 mA/cm² after the addition of methanol to C-800, whereas it increased significantly from 25.7 mA/cm² to 65.24 mA/cm² in AC-800 (after activation). Furthermore, the C-400, C-600, C-800, AC-400, AC-600, and AC-800 electro/nanocatalysts exhibited novel power densities of 12.6, 18.2, 29.7, 16.6, 22.86, and 39.56 mW/cm², respectively. This was further confirmed by their morphological, structural, and electrochemical characteristics. The synthesized materials are proven to be sustainable carbon materials for electron nanocatalyst support and methanol electro-oxidation in DMFC systems because of their low cost, eco-friendliness, high performance, and enhanced porous structure. Moreover, this research provides an effective waste-to-energy approach for converting snail shell biomass into valuable functional carbon materials for renewable energy applications. Full article

This study converted pecan shell waste into magnetic Fe₃O₄@biocarbon for arsenic (V) removal from aqueous medium. A preliminary test was conducted on a binary system of arsenic (V) and lead. A dual-optimization approach was applied using a fuzzy decision network for material synthesis and response surface methodology (RSM) for adsorption performance. The fuzzy model predicted FS2 as an optimal design (particles between 0.38–0.7 mm in size, Fe ratio of 1:1) with high accuracy (R² > 0.95). In the RSM, removal efficiency and adsorption capacity were estimated to find out the influential parameters, which turned out to be adsorbent dose and As(V) concentration. It was predicted that removal capacity would remove 90.99% As(V) at the dose of 0.95 mg L⁻¹ As(V), pH 3.4 and 1.8 g L⁻¹ dose. However, it was also revealed that the q_e model provided a higher confidence (final conditions: 9.95 mg L⁻¹ As(V), pH 3.0 and 0.5 g L⁻¹ dose; q_e = 3.96 mg g⁻¹). Evaluation of Fe₃O₄@biocarbon was conducted at 0.217 mg L⁻¹ As and 34.3 mg L⁻¹ Pb. This suggests removal of lead in addition to arsenic, indicating that the method can be used in multicomponent metal removal. FTIR and XPS analysis showed that removal of As(V) took place through surface complexation with Fe-O and oxygen-containing functional groups. Full article

Currently, heating supply in rural areas of China still predominantly relies on conventional coal-fired heating, which suffers from poor thermal insulation performance and severe environmental pollution. To address the issues of energy waste and environmental pollution associated with traditional heating methods in rural China, this study selects a detached rural residential building in Jilin City as the research object. A building thermal load calculation model incorporating phase-change material (PCM) walls and dynamic simulation models for five clean heating coupling systems are developed using TRNSYS software, so as to analyze the influence of PCM placement at different positions within the wall assembly on the building’s thermal load, as well as the technical and economic performance of the five heating systems. The results show that, when PCM is placed on the inner side of the building envelope, the peak heating load is reduced from 15,234.2 W to 11,266.5 W, and the cumulative heating load drops from 33,744.3 kWh to 25,688.9 kWh. Compared with the conventional PV (photovoltaic) system, the PVT (photovoltaic–thermal) system achieves an 11% improvement in power generation efficiency. Among the five clean heating systems, the PVT–ground-source heat pump system exhibits the lowest energy consumption, while the PVT–biomass boiler system records the highest energy consumption. Based on life-cycle cost analysis, the PVT–biomass boiler system delivers the optimal economic performance, with a levelized annual cost of 9285.48 CNY. Full article

Background: With the growing popularity of golf, the wood consumption and white pollution caused by traditional wooden and plastic golf tees create an urgent need for green, degradable, high-performance alternatives. Materials and Methods: To address this, a novel approach for the green fabrication of high-performance composites was developed utilizing a single agricultural solid waste (chestnut shells) bridged by an extremely low proportion (4 wt%) of a thermoplastic agent (polylactic acid, PLA). A mild dilute hydrochloric acid hydrothermal pretreatment selectively removed hemicellulose to expose active hydroxyl groups, followed by a wet hot-pressing process optimized at 80 °C, 4 h, 15 MPa, and 180 mesh. Results: Under these conditions, the resulting CS-APLA composite tees exhibited a bending strength of 86.32 ± 6.46 MPa and a dynamic impact toughness of 104.89 ± 5.26 kJ/m², representing significant increases of 64.86% and 41.69%, respectively, compared to the pure biomass material, and outperforming conventional commercial wooden tees. A 75-day soil burial test demonstrated a weight loss of approximately 45.42%, confirming a balanced degradation rate. Conclusions: Multi-scale characterization confirmed that the synergistic reinforcement relies objectively on an acid-treatment-induced hydrogen-bonding network coupled with in situ polymer-bridged microdomains formed by PLA flow filling during hot-pressing. This study provides a sustainable route for the high-value utilization of agricultural solid waste. Full article

The development of sustainable adsorbents from industrial biowaste has become an important strategy for reducing the environmental impact of both solid waste generation and wastewater pollution. In this study, residual Saccharomyces pastorianus biomass recovered from the brewing industry was immobilized in a polymeric matrix and evaluated as a bio-composite for the removal of reactive dyes from aqueous media. Orange 16 was selected as the target molecule. Batch biosorption experiments were conducted to identify the optimum operating conditions and to determine the adsorption capacity through Langmuir isotherm analysis. The performance of the biosorbent was subsequently validated under continuous-flow conditions in a fluidized-bed reactor, where the effects of flow rate on column (3.8 and 8.5 mL/min) efficiency were investigated. Experimental breakthrough curves were analyzed using the Clark, Yan, Bohart–Adams, and Yoon–Nelson models, which adequately described the dynamic biosorption process, particularly at the lower flow rate. The best agreement was obtained at a flow rate of 3.8 mL/min, an initial dye concentration of 87 mg/L, and a biosorbent mass of 19.5 g. The developed bio-composite material exhibited efficient dye removal and stable operation, demonstrating that residual brewing biomass can be successfully transformed into a low-cost and sustainable biosorbent suitable for continuous treatment of reactive-dye-containing wastewaters. Full article

Fungal cellulases are key biocatalysts for lignocellulosic biomass valorization and the development of sustainable biorefineries. This review examines recent advances in the production of endoglucanase (EGL), exoglucanase (EXG), and β-glucosidase (BGL) by fungi of the genera Trichoderma, Aspergillus, and Penicillium under solid-state fermentation (SSF) and submerged fermentation (SmF). Emphasis is placed on fermentation strategies, substrate selection, process optimization, and emerging chemometric and artificial intelligence-based approaches. The literature reveals a predominance of SSF systems, especially when agri-food residues such as wheat bran, sugarcane bagasse, rice-derived residues, fruit-processing wastes, and cocoa by-products are employed as low-cost substrates. Among the evaluated genera, Aspergillus was among the most frequently investigated genera and exhibited broad substrate versatility, whereas Trichoderma reesei remains the principal industrial production host for cellulase-rich enzyme preparations used mainly in the saccharification of lignocellulosic biomass for cellulosic ethanol and other biorefinery applications. In contrast, Penicillium stands out as an important source of BGL, complementing cellulase systems derived from other fungi. Temperature, pH, moisture content, and fermentation time were consistently identified as the main factors affecting cellulase biosynthesis, with optimal production generally occurring under mildly acidic conditions and mesophilic temperatures. CCD and BBD were the predominant optimization strategies, while artificial neural network-based models are emerging as promising alternatives. The complementary characteristics of these fungi genera support their application in integrated biomass conversion and future lignocellulosic biorefineries. Full article

Biochar is a porous carbonaceous material synthesized through the pyrolysis of diverse biomass resources, including agricultural and forestry residues as well as livestock manure. It possesses superior characteristics such as a large specific surface area, adjustable pore architecture, abundant surface functional groups, and favorable electrical conductivity. With the increasingly severe global energy shortage and environmental pollution problems in recent years, biochar has emerged as a green, low-cost functional material with distinct application superiority in multiple key research directions, including energy storage and conversion, chemical catalysis, environmental restoration, and signal sensing and detection. This study comprehensively summarizes the latest research advances of biochar in the aforementioned application fields, focusing on innovative achievements in photocatalytic and electrocatalytic hydrogen generation, supercapacitors and electrochemical energy storage systems, persulfate activation technology, carbon dioxide capture, remediation of heavy metal and organic contaminants, volatile organic compound (VOC) adsorption, as well as electrochemical sensing devices. Existing research results demonstrate that modification strategies including metal and non-metal doping, surface oxidation treatment, and compounding with semiconductors or metal oxide materials can effectively improve the catalytic activity and functional performance of biochar. Furthermore, this paper prospects the future interdisciplinary development trends of biochar, analyzes the existing research gaps in mechanism exploration, structural optimization design, and industrial large-scale preparation, and provides theoretical and practical references for the further popularization and application of biochar in sustainable energy development and environmental governance fields. Full article

Lignocellulosic fruit peel waste represents an abundant, carbon-neutral feedstock for green biohydrogen production via dark fermentation, yet its rigid compact structure and high cellulose crystallinity severely restrict saccharification and fermentative hydrogen yield. In this study, a hydrothermal acidification pretreatment strategy was proposed to boost dark fermentative biohydrogen generation from navel orange peel waste, and systematic investigations were conducted to reveal the regulating mechanisms of key pretreatment parameters (hydrochloric acid concentration, pretreatment temperature, duration) on reducing sugar release and hydrogen-producing performance. Multiscale characterizations including SEM, XRD, FTIR, and TG were integrated to unravel the microstructural and chemical compositional evolution of raw and pretreated substrates. The results demonstrated that hydrothermal acidification effectively disrupted the dense lignocellulosic network of navel orange peel, lowered cellulose crystallinity, and greatly improved substrate accessibility for hydrolytic reactions and microbial adhesion. Under the optimal pretreatment condition (1.0 mol/L HCl, 120 °C, 1 h), the concentration of released reducing sugars reached 10.2 g/L, which was 67.2% higher than that of untreated raw peel. The corresponding maximum cumulative hydrogen yield attained 36.5 mL H₂/g TS, representing a 67.4% improvement relative to the untreated control group. Pearson correlation analysis verified that pretreatment temperature, acid concentration, and duration exhibited strong positive correlations with hemicellulose and cellulose removal efficiencies, while excessive pretreatment (HCl > 1.0 mol/L, temperature > 120 °C, duration > 1 h) generated inhibitory by-products that suppressed microbial hydrogen evolution. This study comprehensively clarifies the structural modification and biohydrogen promotion mechanism of hydrothermal acidification pretreatment on pectin-rich biomass, and delivers a cost-effective, facile technical route for high-value energy valorization and harmless disposal of fruit processing solid wastes. Full article

Rapid population growth, urbanization, and industrialization are continuously increasing global energy demand while intensifying climate change associated with fossil fuel consumption. In this context, renewable energy production from organic waste has gained increasing attention as a sustainable and environmentally friendly strategy. Anaerobic digestion (AD) offers significant potential for simultaneous waste stabilization and biomethane generation. However, many previous studies investigating lignocellulosic or nutrient-rich substrates have relied on physical, chemical, or thermal pretreatment methods to enhance biodegradability, despite their additional operational costs, energy consumption, and environmental impacts. Therefore, developing low-cost and pretreatment-free co-digestion strategies remains an important research need. This study investigated the biomethane production potentials of untreated chicken manure (CM) and duckweed (Lemna minor-LM) collected from the final sedimentation tanks of wastewater treatment plants under mono-digestion and co-digestion conditions. The study hypothesized that rapidly growing and widely available LM biomass could enhance methane production without requiring pretreatment. Among all reactors, CM0.75 (75% of the total TS derived from CM and 25% from LM and inoculum) achieved the highest performance with a cumulative biogas production of 5350 mL (74.2% of CH4) and a methane yield of 327 mL CH4/g VS, while mono-digestion of CM resulted in the lowest methane yield of 104 mL CH4/g VS. The results demonstrated that LM biomass naturally proliferating in wastewater treatment plants can be directly utilized as an effective co-substrate to improve biomethane production from poultry wastes. The proposed approach provides a cost-efficient, eco-friendly, and circular-economy-oriented alternative by eliminating the need for pretreatment while simultaneously valorizing problematic biomass generated in wastewater treatment facilities. Full article

Municipal solid waste landfill leachate represents one of the most environmentally challenging liquid effluents in modern waste management; however, its high nitrogen and phosphorus content renders it a potentially valuable nutrient source for microalgal phycoremediation. Here, Chlorella sp. and Scenedesmus sp. were cultivated for 15 days in CHU-10 standard medium and 50% (v/v) municipal landfill leachate from Nauta, Peru, and characterized across 33 biochemical variables, 14 physicochemical parameters, and 32 metal ions and trace elements. A sequential competitive multivariate pipeline comprising principal component analysis (PCA), hierarchical cluster analysis (HCA), permutational multivariate analysis of variance (PERMANOVA), and linear discriminant analysis (LDA) was applied to both the biochemical and bioremediation datasets. Leachate supplementation increased peak biomass density by 26.6–28.3% and elevated total protein by 56.9% in Chlorella sp. and 73.4% in Scenedesmus sp., while reducing total lipids by 37–46% and suppressing polyunsaturated fatty acid production. Both species achieved net biological removal efficiencies (NBRE) exceeding 86% for ammonium and ammonia; toxic elements, including Cd (~96%), Al (~92%), As (~90%), and Pb (~90%), were removed at higher NBRE than macro- and micronutrient categories. LDA achieved 100% leave-one-out cross-validation accuracy for species classification from both physicochemical and 32-element NBRE profiles. These findings indicate two complementary valorization directions, contingent on further biomass safety verification: leachate-grown Scenedesmus sp. shows a favorable combination of protein enrichment and nutrient removal for single-cell protein production integrated with bioremediation, while Chlorella sp. in standard medium shows a more favorable fatty acid profile for nutraceutical applications. Because leachate-grown biomass also accumulates inorganic and trace-element constituents from the medium, its suitability for protein or nutraceutical use requires direct heavy-metal characterization of the harvested biomass, independent of the demonstrated removal efficiency from the liquid phase. Full article

Considering carbon neutrality and fossil fuel depletion, biomass is becoming increasingly important as a renewable and sustainable energy source. However, understanding of process-dependent characteristics relevant to char production remains limited. This study investigated the carbonization of mushroom waste medium (MWM) via conventional carbonization (CC; i.e., pyrolysis), hydrothermal carbonization (HTC), and microwave-assisted carbonization (MAC), and evaluated their suitability for desired char properties and target applications. For all methods, increasing reaction temperature led to carbon densification, with decreased oxygen and hydrogen contents and increased carbon and fixed carbon fractions. However, the extent of these transformations depended on the reaction environment. HTC achieved carbon enrichment and the highest higher heating value (HHV) at relatively low temperatures. In contrast, CC required higher temperatures to achieve comparable carbonization levels but showed a marked increase in BET surface area at higher temperatures. MAC exhibited intermediate characteristics under moderate conditions. HTC also facilitated potassium and chlorine removal, which may reduce operational issues during thermal utilization. These results indicate trade-offs among carbon densification, char yield, surface structure, and inorganic matter content. Rather than identifying a universally superior process, this study demonstrates that the suitability of each method depends on the desired properties and applications of MWM-derived char, providing a practical basis for appropriate process selection. Full article

Transforming waste and agricultural-residue biomass into bioenergy is central to the circular bioeconomy, yet routing such heterogeneous residues to the right thermochemical pathway depends on the higher heating value (HHV), which is conventionally measured by slow, resource-intensive bomb calorimetry. Here, we present an explainable alternative that predicts HHV from inexpensive elemental inputs. We used a publicly archived compilation of 344 literature-reported biomass samples retrieved from an open data repository rather than assembled by the authors, including carbon (C), hydrogen (H), oxygen (O), nitrogen (N) and sulfur (S). Measured HHV was the target. The samples spanned woody, herbaceous and agricultural-residue biomass, and they were standardized through duplicate removal, consistency verification and outlier assessment. On these features, we developed a stacked hybrid model combining Random Forest, eXtreme Gradient Boosting and Artificial Neural Networks, which estimated the HHV with $R^2$ = 0.99, RMSE = 0.45 MJ/kg and MAE = 0.30 MJ/kg. SHAP and LIME analyses showed that carbon exerts the strongest positive influence on HHV, whereas oxygen contributes negatively, which is consistent with established thermochemical principles. Within the compositional range covered by the training data, and subject to the absence of external validation, the framework offers a fast and interpretable complement to bomb calorimetry for screening residue biomass. Full article

The sustainable utilization of post-consumer plant biomass as a precursor for functional carbon materials has attracted increasing attention as an environmentally friendly approach to heterogeneous catalyst development. In this study, the aerial parts of Pelargonium zonale were converted into activated carbons by chemical activation with KOH at carbonization temperatures of 750, 800, and 850 °C. The obtained materials were comprehensively characterized using N₂ adsorption–desorption, XRD, FTIR, UV–Vis spectroscopy, XRF, and SEM. Increasing the carbonization temperature promoted pore development, resulting in activated carbons with a maximum specific surface area of 1578 m² g⁻¹ and a total pore volume of 0.751 cm³ g⁻¹. The catalytic performance of the obtained materials was evaluated in the oxidation of geraniol. No direct correlation between the textural properties of the activated carbons and their catalytic performance was observed, suggesting that catalytic behaviour results from the combined effect of several physicochemical properties. Optimization of the reaction conditions demonstrated that catalytic performance depended on the combined influence of reaction temperature, catalyst amount, reaction time, and catalyst properties. Under the optimized reaction conditions (110 °C, 0.5 wt% catalyst, and 360 min), the highest geraniol conversion (37 mol%) was achieved over CP_KOH_850. Kinetic modelling confirmed that geraniol oxidation proceeds through a complex network of parallel and consecutive reactions leading to the formation of citral, 2,3-epoxygeraniol, 2,3-epoxycitral, and other oxidation products. These findings demonstrate that waste Pelargonium zonale biomass is a promising renewable precursor for the preparation of functional carbon materials for heterogeneous catalytic applications. Full article