Search Results (671)

Given the confining effect of porous carbon and strong surface polarity of transition metal phosphides, their composite would be a promising cathode candidate to solve the problems of lithium–sulfur batteries including volume expansion and the shuttling effect of polysulfides. Herein, cobalt phosphide (CoP)-loaded phosphorous (P)-containing carbonized bamboo (CoP/PCBs) composites were fabricated via the co-pyrolysis of phytic acid, waste bamboo and Co(NO₃)₂·6H₂O via Joule heating at 600–1200 °C. Hydrogen radicals released from phytic acid enabled CoP/PCBs with developed porosity (438.1–812.4 m²/g). CoP nanoparticles coated with graphitic carbon were distributed uniformly on a porous matrix of PCBs. CoP/PCBs presented obviously enhanced adsorption capabilities for Li₂S₆, and 57.8–80.4 wt.% of sulfur was confined in CoP/PCBs/S cathodes. CoP/PCB heated at 1200 °C exhibited a high reversible capacity of 477.5 mAh/g after 500 cycles at a current density of 1 C with an average capacity decay rate of 0.045%. The specific capacity remained at 453.3 mAh/g after 300 cycles even under a high sulfur load of 4.0 mg/cm². Conversion of sulfur/polysulfides during the electrochemical process could be promoted via the physical confinement of sulfur and chemical confinement of Li₂S₆. This work provided a valuable reference for the facile fabrication of lithium–sulfur cathodes and utilization of metal phosphides in advanced lithium–sulfur battery systems. Full article

Mixed cotton–polyester textile waste remains difficult to recycle because processes that recover synthetic polymers often leave the cotton fraction underused, while cellulose extraction methods may compromise the polyester component. This study investigates whether cotton in such blends can be converted into high-quality microcrystalline cellulose while retaining the potential value of the recovered polyester fraction. Cotton waste and cotton–polyester blends were treated using aqueous sulfuric acid at different conditions: from 15 to 20% acid concentration and from 70 to 80 °C for five to ten hours. The recovered microcrystalline cellulose was characterised and compared to commercial microcrystalline cellulose, while the polyester fraction was assessed using tensile testing. Enzymatic hydrolysis and a dimethyl sulfoxide co-solvent approach were evaluated as alternatives. The aqueous acid process yielded 82 to 97% microcrystalline cellulose from cotton waste and up to 51% from blended waste. The recovered cellulose showed around 10% higher crystallinity than commercial material and a similar particle size distribution, although morphology depended on the feedstock. The polyester fraction showed only minor reductions in tensile performance. The novelty of this study lies in the demonstration of a simple, ionic-liquid-free, single-reagent route that valorises both material streams from cotton–polyester textile waste. Full article

Lead-bearing dusts from metallurgical processes are hazardous secondary resources due to their complex composition and toxicity. At the same time, their high lead content makes them a promising feedstock for resource recovery. This study proposes an energy-efficient electrosmelting approach based on the partial substitution of sodium carbonate with calcium-rich industrial waste (sugar-industry defecate). Thermodynamic analysis and equilibrium modeling of the Pb–Sb–Fe–Na–Ca–Si–S–Cl–As system were performed in the temperature range of 200–1200 °C using Outotec HSC Chemistry. The results indicate that under equilibrium conditions approximately 90–95% of lead is concentrated in the metallic phase (~56 kg from ~60 kg in the feed), while antimony is co-recovered (~1.9–2.0 kg). The slag is dominated by calcium silicates, primarily Ca₂SiO₄, confirming the important role of CaO in slag formation and impurity fixation. Chlorine is predominantly bound as NaCl and partially as CaCl₂, while sulfur is distributed between Na₂S and Na₂SO₄. A significant portion of arsenic is predicted to be retained in the slag as calcium and sodium arsenates (Ca₃(AsO₄)₂ and Na₃AsO₄), whereas its volatilization is thermodynamically negligible under equilibrium conditions. Preliminary experimental results are generally consistent with the thermodynamic predictions and confirm the feasibility of partially replacing Na₂CO₃ with sugar-industry defecate. The proposed approach contributes to reducing the consumption of conventional fluxes and promotes the utilization of industrial waste within a circular-economy framework. Full article

Global demand for sustainability drives interest in bioenergy from sustainable feedstock. Agro-industrial waste such as brewer’s spent grains (BSG) is an important by-product of brewing. This study provides a comprehensive review of the current technologies of BSG for energy recovery and BSG-based materials for energy storage applications. The latest scientific progress, not only from conventional processes on anaerobic digestion, combustion, gasification, pyrolysis, torrefaction, and hydrothermal liquefaction but also from several integrated technologies, pretreatment methods, and additives/catalysts regarding the improvement of energy efficiency and process sustainability, was reviewed. In addition, the co-feedstock practices (co-combustion, anaerobic co-digestion, hydrothermal co-liquefaction, anaerobic co-fermentation) and co-production were examined. AD of BSG yields about 302 NL CH₄/kg COD, generating roughly 0.39 kWh of electricity/kg BSG and 1.71 MJ of thermal energy/kg BSG. Ultrasonic pretreatment enhances methane production up to four times (107 L CH₄/kg TVS) and reduces CO₂ emissions by 0.083 t CO₂eq/t BSG. Anaerobic co-digestion of BSG with other brewery waste increased the yield up to 88 mL CH₄/g TVS, generated approx. 0.348 kWh/kg TVS electricity, and reduced emissions by 0.114 kg CO₂eq/kg TVS. Bioethanol yields can reach 72%, while biohydrogen generation was up to 5154 mL H₂/g glucose. BSG pyrolysis provides up to 71.8% bio-oil, and its calorific value is 18–25 MJ/kg. BSG-derived activated biocarbon has a notable surface area (1792 m²/g) for lithium–sulfur batteries. The assessment showed that BSG’s transformation into bioenergy and energy storage materials aligns with waste reduction and sustainable development goals. However, future research on combined alternative wastes, integrated technologies, green nanotechnology, and artificial intelligence technology could lead to optimal performance and facilitate their industrial application. Full article

Olive pomace is a major side stream originating from olive processing for the production of olive oil. This waste material bears a load of polyphenolic antioxidants, and thus it might serve as a source of precious phytochemicals. This work had as its objective the development of an extraction process for the efficacious recovery of polyphenols from dried olive pomace (dOP), employing eco-friendly extraction media. To this end, environmentally benign solvents were first compared for their efficiency in obtaining increased yields in total polyphenols, and 40% aqueous isopropanol was selected as the best-performing mixture. Further examination of the role of acidification showed that mineral acid addition (sulfuric, hydrochloric) had a rather negative effect on polyphenol yield. To the contrary, incorporation of oxalic acid into the solvent at a 10% level provided significantly higher extraction yield (p < 0.05), which reached 27.1 ± 1.1 mg caffeic acid equivalents (CAE) per g dOP. This solvent system (40% isopropanol/10% oxalic acid) was additionally scrutinized for its effectiveness by studying the role of process severity and response surface optimization. Out of both approaches, it was demonstrated that polyphenol extraction yield, but also antiradical activity, was directly correlated with residence time and temperature, within the limits tested. Moreover, a high correlation between polyphenol concentration and antiradical activity was also revealed. Liquid chromatography-tandem mass spectrometry analyses showed that the extract obtained with the solvent system used (40% isopropanol/10% oxalic acid) was characterized by the presence of both hydroxytyrosol and the flavone luteolin (242.1 and 178.6 μg g⁻¹ dOP, respectively), but, in the absence of isopropanol, the extract produced was largely dominated by hydroxytyrosol (4629.7 μg g⁻¹ dOP). Thus, it was concluded that the solvent system could fundamentally diversify extract composition. It is proposed that, when combined with integrated biorefinery technologies, this approach could effectively contribute to reducing environmental impacts while enabling the production of valuable natural antioxidants or platform chemicals that are vital for the food, pharmaceutical, and cosmetic industries. Within the broader context of sustainable food waste management, such strategies might be key elements of a circular economy framework. Full article

Air pollution is primarily caused by human activities such as industrial emissions, road traffic, waste incineration, and fossil fuel power plants. Pollution refers to the presence of harmful substances in the air, such as nitrogen dioxide (NO₂), sulfur dioxide (SO₂), ozone (O₃), carbon monoxide (CO), and other environmental pollutants. Some pollutants pose health risks even at low doses. Given the critical importance of air quality, monitoring air pollution has become an urgent and essential subject. Air quality monitoring relies on accurate data, so changeable environments and sensor issues make using interval diagnostic techniques for addressing uncertainty in systems interesting. In this article, we focus on three key aspects to achieve precise and efficient results: (1) the use of an accurate fault detection method that accounts for data uncertainty while maintaining model symmetry, (2) the implementation of a reliable detection index invariant to symmetric sensor behaviors, and (3) the combination of both to improve fault localization accuracy. This paper presented a fault detection and localization framework designed for uncertain and nonlinear monitoring environments. A novel fault-sensitive detection index was developed and integrated into an elimination-based localization strategy within a reduced-rank interval kernel PCA (RR-IKPCA) model. By exploiting information contained in modified residual subspaces and explicitly accounting for measurement uncertainty, the proposed approach enhances fault sensitivity while preserving robust localization capability, as validated on the AIRLOR air quality monitoring network. Full article

The separation of copper and arsenic from spent copper electrolyte plays a pivotal role in electrolyte recirculation and arsenic-bearing solid hazardous waste minimization. In this study, the deep copper removal process in high arsenic and low copper spent copper electrolyte by gas–liquid sulfidation is studied. Thermodynamic analysis indicates that under strongly acidic conditions, regulating the oxidation-reduction potential enables the selective precipitation of Cu²⁺ as CuS while inhibiting the formation of As₂S₃. The influence of hydrogen sulfide excess coefficient and gas–liquid sulfidation temperature on copper and arsenic co-precipitation behavior is investigated. Under the optimal gas–liquid sulfidation conditions with the sulfide excess coefficient of 47 and gas–liquid sulfidation for 60 min at 328.15 K, the copper concentration can be reduced from 0.312 g/L to 1.25 mg/L, while arsenic co-precipitation can be effectively suppressed. The copper gas–liquid sulfidation process is chemical reaction and diffusion mix controlled with an activation energy of 33.47 kJ/mol, while arsenic sulfidation is chemical reaction controlled with an activation energy of 51.22 kJ/mol. The copper–arsenic co-precipitated sludge predominantly consists of As₂S₃, CuS, and Cu₂S. Arsenic precipitation involves a multi-step process: As(V) is first reduced to As(III) and subsequently sulfurized. However, the majority of cupric ions are directly precipitated as sulfides, whereas a minor fraction is firstly reduced by hydrogen sulfide and subsequently precipitated. The present study clarifies the intrinsic mechanism and external regulatory factors for the gas–liquid sulfidation deep copper removal process, providing a theoretical basis for optimizing sulfidation processes to synergistically achieve valuable metal recovery and arsenic pollution control. Full article

Spent mushroom substrate (SMS) return is a vital strategy for agricultural waste recycling and soil fertility improvement, yet its ecological impacts of duration remain poorly understood. This study employed metagenomic sequencing to explore soil fertility, microbial dynamics, and nitrogen cycling across different SMS return durations (0, 1, and 3 years) within rice–mushroom crop rotation systems. Soil nutrients (organic matter, total nitrogen, total phosphorus) initially decreased and then increased throughout the rice growth cycle. The one-year return (y1) induced early nutrient depletion, whereas the three-year return (y3) significantly enhanced late-stage nutrient accumulation. With increasing duration, bacterial and archaeal assembly shifted from stochastic toward deterministic processes, while fungal diversity and stochasticity decreased continuously. Co-occurrence network analysis demonstrated that SMS return increased network complexity and intercommunity competition. This transition was accompanied by a functional shift in keystone taxa from those responsive to exogenous organic matter in y1 to those mediating nitrogen fixation, anammox, and sulfur metabolism in y3. Nitrogen cycling in y1 increased potential N₂O emission risks through nirS upregulation and nosZ downregulation, whereas y3 mitigated inorganic nitrogen loss by upregulating gene abundances of ammonia assimilation, nitrification, and DNRA genes. Notably, the structure of nitrogen-cycling genes fluctuated in y1 but was resilient to y0 levels in y3. These findings demonstrated that while initial SMS return triggered ecological fluctuations and environmental risks, continuous return (y3) achieved functional stability by reshaping microbial niches. This study highlights the importance of SMS return duration in balancing soil fertility enhancement with environmental risk mitigation in sustainable paddy ecosystems. Full article

The growing global demand for sustainable biotechnological routes for bioenergy production has paved the way for Brazil to position itself as a strategic leader due to its vast agricultural production and, consequently, agricultural residues, among which rice husk stands out. Although rice husk is widely used for energy cogeneration, its potential for producing high-value platform chemicals remains underexplored. This study aims to evaluate the production of value-added pyrolytic derivatives from rice husk by investigating the synergy between acid pretreatments and fast pyrolysis temperatures (350–600 °C). Thus, the experimental strategy involved intensifying the production of target compounds in the condensable fraction (bio-oil) from pyrolysis gases using different biomass pretreatments before fast pyrolysis according to the following conditions: (i) acid washing using acetic acid (10%), (ii) acid washing using nitric acid (0.1%) followed by impregnation using sulfuric acid (0.1–0.3%), and (iii) impregnation using sulfuric acid alone (0.1–0.3%). Fast pyrolysis was carried out over a temperature range of 350–600 °C using a pyroprobe microreactor coupled to a mass spectrometer (GC/MS). The best results, regarding overall volatile fraction, were observed when impregnation with 0.3% sulfuric acid was used prior to pyrolysis at 600 °C, resulting in around an 8.88-fold increase compared with untreated biomass. Nevertheless, the experimental conditions that favored the formation of our main chemical targets, such as levoglucosan, furfural and some phenols, were different. For instance, levoglucosan, furfural and eugenol increased by 21-, 10- and 22-fold, respectively, for biomass treated with HNO₃ (0.1%)/H₂SO₄ (0.2%) at 450 °C, whereas phenol and 4-vinylphenol increased by 35- and 14-fold at 500 °C. These findings can be considered satisfactory, highlighting the potential of the thermochemical conversion process as a valuable tool for the production of high-value chemicals from agricultural waste like rice husk. Full article

This study aims to develop a sustainable, low-cost, and high-performance supercapacitor electrode by valorizing waste date seeds (Phoenix dactylifera) into activated carbon and integrating it with a polymer-based hydrogel electrolyte. Waste date seeds were successfully converted into high-performance activated carbon through hydrothermal carbonization followed by sulfuric acid (H₂SO₄) chemical activation. The obtained date seed activated carbon (DSAC) was applied as an electrode material and incorporated into a hydrogel electrolyte for supercapacitor applications. Structural, thermal, and morphological analyses using SEM, FTIR, XRD, and TGA confirmed the formation of a predominantly microporous carbon framework enriched with oxygen-containing functional groups, indicating effective carbonization and activation. The porous structure and surface chemistry contributed to enhanced electrochemical behavior. The electrochemical behavior of the prepared DSAC electrode was investigated through cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) analyses. The material exhibited a highest specific capacitance of 179 F g⁻¹ at a scan rate of 5 mV s⁻¹ and 159 F g⁻¹ at a current density of 0.2 A g⁻¹, demonstrating reliable and stable capacitive characteristics suitable for biomass-derived carbon-based supercapacitor applications. The device also exhibited excellent cycling stability over 5500 cycles, confirming long-term durability. The results demonstrate a promising and environmentally friendly strategy for advanced energy storage systems. Furthermore, the sustainability and cost-effectiveness of the proposed approach are attributed to the utilization of abundant date seed biomass and the simplicity of the hydrothermal–chemical activation process. The enhanced electrochemical performance is primarily associated with the hierarchical porous structure of the activated carbon and the improved ion transport facilitated by the hydrogel electrolyte, which collectively contribute to stable capacitive behavior and long-term cycling durability. Full article

With the rapid development of the edible fungus industry, the environmental pressure and resource waste caused by the massive generation of fungal residue have become increasingly prominent. Meanwhile, heavy metal wastewater pollution and the growing demand for clean energy pose dual challenges to sustainable development. This study focuses on Auricularia cornea var. Li. fungal residue, exploring the establishment of a multi-level resource utilization pathway integrating “porous carbon material preparation—heavy metal adsorption—photocatalytic hydrogen evolution.” Firstly, the Auricularia cornea var. Li. residue-based porous carbon material was examined by combining hydrothermal carbonization, activation and slow pyrolysis. In optimal conditions, the porous carbon obtained yielded a surface area of 675.56 m²/g and formed a composite pore structure consisting of micropores with coexisting micropore and mesopore. Secondly, we performed batch adsorption experiments to study the effects of solution pH, adsorbent dosage and contact time and the adsorption behavior via fitting adsorbing kinetic models. Under optimal conditions, Cd(II) removal efficiency reached 92.36% and an equilibrium adsorption capacity of 92.47 mg/g. We used Cd(II) adsorbed porous carbon as a cadmium source and converted into a CdS photocatalyst using a hydrothermal sulfidation process. The CdS prepared using sodium sulfide as a sulfur source gave an average hydrogen evolution rate of 668.01 μmol·g⁻¹·h⁻¹ and showed higher photocatalytic performance for water splitting to produce hydrogen. Full article

The composition and type of polymers used as feedstocks in the pyrolysis of plastic waste determine the decomposition process and the proportions of the final products. This paper examines the effect of feedstock heterogeneity on pyrolysis efficiency and pyrolysis gas composition. Four types of plastic waste were considered: real polyolefin waste of municipal origin, LDPE, Alu-PEX laminates, and an alternative refuse-derived fuel (RDF). Low-temperature pyrolysis (450 °C) was conducted in a laboratory reactor, and the gas composition was analyzed using GC-TCD/FID gas chromatography, which allowed for the determination of light hydrocarbons, oxygenates, and sulfur content. Compared to RDF, both municipal and LDPE polyolefin wastes produced gas with a higher calorific value and a predominance of light C₁–C₄ hydrocarbons, while Alu-PEX laminates produced gas rich in C₁–C₂ and low in sulfur, suitable for direct use. RDF was characterized by increased CO₂ and non-flammable gas production and significantly higher sulfur content, requiring advanced purification. The results emphasize the importance of feedstock segregation and standardization and demonstrate that pyrolysis of polyolefins and Alu-PEX laminates can provide higher-quality energy gas than RDF, supporting the circular economy and energy self-sufficiency of industrial installations. Full article

Aiming at the problem of heavy metal release from ultra-low-grade waste rock caused by the coupling of natural weathering and acid-rain leaching, black shale gravel of the Cambrian Series in western Hunan was taken as the research object. Gradient mechanical crushing was used to simulate physical weathering, and sulfuric–nitric acid-type simulated acid rain was prepared for continuous leaching experiments. Combined with ICP-MS monitoring and SEM-EDS characterization, the effects of crushing intensity on the physicochemical properties of leaching system and heavy metal release kinetics were systematically analyzed. The results showed that the pH of the leaching system presented three evolutionary stages: acid-dominated, alkaline transition and buffer stabilization. Heavy metal release could be divided into three types according to their occurrence forms: the sulfide-phase-sensitive type (Cd, Zn), secondary stable type (Pb), and silicate lattice bound type (Cu, Ni, Cr). The promotion effect of crushing on interface reaction activity showed diminishing marginal effect, and the particle fractal dimension increased from 2.15 to 2.67. It was concluded that the core controlling factor of heavy metal release risk is the selective exposure degree of occurrence mineral phases by physical disturbance. A coupling framework of “physical weathering–mineral exposure–release response” was established, providing a scientific basis for the differentiated management and control of heavy metals in filling sites. Full article

Radionuclide contamination of surface water bodies poses a significant environmental challenge, particularly for low-productivity dystrophic systems where natural self-purification capacity is limited. This study aimed to assess the potential of phytoplankton and bottom sediments as biogeochemical barriers for radionuclides. Laboratory modeling of ⁹⁰Sr, ²³³U, ²³⁹Pu, and ²⁴¹Am accumulation was conducted using samples of Lake Dryazlo (Tver Oblast) water and bottom sediments as a representative dystrophic model system. Sorption onto phytoplankton biomass over a single growing season was estimated at 1.89 × 10⁴, 5.41 × 10⁴, 6.64 × 10⁴, and 4.04 × 10⁴ Bq g⁻¹ dry biomass for ⁹⁰Sr, ²³³U, ²³⁹Pu, and ²⁴¹Am, respectively. Actinide immobilization in bottom sediments depended on mineral composition and microbial community activity. Ammophos addition increased radionuclide removal from the liquid phase by 2–5-fold through enhanced phytoplankton productivity, and promoted actinide fixation via phosphate mineral phase formation and stimulation of anaerobic sulfur- and iron-cycling bacteria. These results demonstrate a viable biogeochemical barrier approach applicable to the decommissioning of radioactive waste storage ponds and remediation of radionuclide-contaminated water bodies. Full article

Four algal adsorbents were prepared from two types of green sea algae (Ulva lactuca and Ulva pertusa), either by treatment with concentrated sulfuric acid or without treatment. A comparative study of Au(III) adsorption in an HCl medium was performed. While both untreated adsorbents showed good performance at low HCl concentrations, the treated adsorbents achieved quantitative adsorption and high selectivity for Au(III) across a broad range of HCl concentrations. The adsorption of Au(III) onto the algal biomass adsorbents followed the typical Langmuir monolayer adsorption model. At an HCl concentration of 0.010 M, the maximum adsorption capacities were 1.14, 0.86, 6.57, and 6.28 mol kg⁻¹ for DUL, DUP, TUL, and TUP, respectively. A kinetic study conducted at different temperatures was consistent with the pseudo-first-order kinetic model and enabled estimation of the activation energy of the adsorption reaction. Structural changes before and after treatment were analyzed using FT-IR spectroscopy. Confirmation of Au(III) adsorption and its subsequent reduction to the elemental state was achieved through XRD and SEM/EDX analyses as well as digital imaging of the Au-loaded adsorbents. Finally, the adsorbed and reduced Au was successfully desorbed using an acidic thiourea solution. Full article