Search Results (6,079)

The rapid increase in end-of-life lithium-ion batteries demands sustainable recycling routes for lithium recovery. This work presents a novel integrated hydrometallurgical–electrodialysis process designed specifically for recovering lithium from off-specification NMC cathode materials while enabling full reagent recyclability. Selective leaching with oxalic acid was optimised by setting the water-to-oxalic acid dihydrate ratio (H₂O/OA·2H₂O) to 7.3:1 w/w, achieving 81% lithium extraction at room temperature within 2 h while limiting the co-dissolution of Ni, Co and Mn to 0.2%, 1.6% and 1.7% by weight, respectively. The resulting leachate was processed in a four-chamber electrodialysis cell equipped with two Nafion 117 cation-exchange membranes and one Neosepta AMX-fmg anion-exchange membrane operating at −1.6 V versus Ag/AgCl, enabling 96% lithium recovery and 98% oxalic acid recovery. The regenerated oxalic acid stream (41.8 g L⁻¹) was fully restored to its initial concentration and reused in successive cycles without performance loss. Subsequent precipitation of lithium with Na₂CO₃ yielded 99.3%-pure Li₂CO₃. This combined leaching–electrodialysis–precipitation presents a high selectivity, low-waste, circular recovery system, offering a scientifically original approach that integrates reagent regeneration with high-purity lithium production. Full article

Ferronickel slag, as a major solid waste in the stainless-steel industry, poses a serious threat to the environment due to its large-scale production and low utilization rate. In this study, magnesium oxide in the ferronickel slag was leached out and converted into high-purity magnesium sulfate, while the leach residue was utilized for cement clinker production. During the complete utilization of ferronickel slag, the Mg leaching efficiency reached 90.75% and was significantly enhanced by reducing the particle size of the ferronickel slag with H₂SO₄ solution as the sole solvent. High-purity magnesium sulfate with a purity of 99.92% was prepared from the leachate through a multi-step process involving primary crystallization, purification, and secondary crystallization. The leach residue, accounting for 68.20% of the original mass, was primarily composed of 79.4 wt% SiO₂ and less than 6.1 wt% MgO and is used as a key raw material in the production of Portland cement. Sintering temperature significantly influenced the structure and properties of the resulting cement. Both the Portland clinker and cement were successfully produced at sintering temperatures of 1400 °C and 1450 °C when the leach residue was used as a primary raw material, with well-developed cementitious phases of calcium silicate and aluminate formed during calcination. The setting time, soundness, and compressive and flexural strengths of the hardened C1400 and C1450 mortars met the requirements specified in relevant standards. Through this integrated process, the overall utilization rate of the ferronickel slag reached 100%. Based on a preliminary estimate, full utilization of the annual ferronickel slag production in China could substitute at least 19.5 million tons of magnesite and 15.0 million tons of silica and reduce CO₂ emissions by 10.3 million tons. Full article

This paper presents the results of a laboratory-based treatability study conducted for a confidential former wood treating site heavily impacted by a creosote non-aqueous-phase liquid (NAPL) containing pentachlorophenol (PCP). PCP impacts in the silty sands extended to approximately 33 ft (10 m) below the ground surface (bgs), with discrete soil samples containing PCP concentrations up to 14,500 mg/kg, and groundwater PCP concentrations forming a main plume exceeding 1 mg/L over 2.16 acres (0.87 ha). Treatability testing was performed on unspiked and NAPL-spiked site soils with total PCP concentrations ranging from 10 to 100 mg/kg, respectively, and leachable PCP concentrations of approximately 3 to 8 mg/L. Stabilization/solidification (S/S) mix designs using 5 to 10 weight percent (wt%, dry-reagent-to-wet-soil mass basis) of a Portland cement (PC) blend and 1 wt% powdered bentonite met the minimum unconfined compressive strength (UCS) and maximum hydraulic conductivity (K) performance criteria of 50 lb/in2 (345 kPa) and 1 × 10⁻⁶ cm/s, respectively, within the specified 28-day cure time. Long-term semi-dynamic leach testing was performed on S/S-treated soils using a modified United States Environmental Protection Agency (EPA) Method 1315 test incorporating a polydimethylsiloxane (PDMS) liner to improve the data reliability for hydrocarbons. Results showed that adding 1 wt% organoclay (OC) to the S/S mix designs did not substantially reduce leaching of common semi-volatile organic compounds (SVOCs) such as naphthalene, acenaphthene, phenanthrene and benzo(a)anthracene compared to mixes using only the PC blend with bentonite, consistent with previous studies. However, the inclusion of OC had a decisive effect on PCP immobilization, providing an order-of-magnitude (10×) reduction in the cumulative mass release of PCP over the test duration. This benefit diminished with decreasing degree of chlorination for other phenolic compounds. Full article

Analyzing the hydrochemical characteristics and formation mechanism of metasilicic acid (H₂SiO₃) enrichment in the groundwater of Sanjiang Plain is conducive to guiding the rational development and utilization of mineral water resources in this region. Taking the groundwater in the typical black soil area of the northeastern Sanjiang Plain (from Qindeli Farm to Chuangye Farm) as an example, 104 groups of groundwater samples were collected to analyze enrichment and controlling factors of H₂SiO₃ by comprehensive methods such as hydrochemical analysis, rock geochemistry, water–rock interaction analysis, and ion ratio analysis. The results showed that the groundwater was generally in a reducing environment with low mineralization and weak acidity. The main cations were Ca²⁺ and Mg²⁺, and the main anion was HCO₃⁻. The hydrochemical types were mainly HCO₃–Ca and HCO₃–Ca·Mg, followed by HCO₃·Cl–Ca·Mg mixed type, and the H₂SiO₃ enrichment rate of groundwater reached 80.77%. The enrichment of H₂SiO₃ in the groundwater was related to the local geological structure and specific hydrogeochemical processes, and mainly controlled by the hydrolysis process of silicate rock minerals (such as albite, plagioclase, and olivine). The silicates and aluminosilicates contained in the basalt, diorite, and gneiss distributed in the area provided a rich material basis for the enrichment of H₂SiO₃. Its migration and distribution were simultaneously affected by leaching and cation exchange, while NO₃⁻ and SO₄²⁻ input from anthropogenic sources also participated in the rock weathering, specifically the enrichment process of H₂SiO₃ in the groundwater. From the perspective of mineralization conditions, Qinglongshan Farm and Qindeli Farm are potential areas for developing H₂SiO₃-rich mineral water. However, the main direction for the development and utilization of groundwater in this area should be to explore natural H₂SiO₃-rich groundwater with good comprehensive water quality. Full article

This study addresses the challenge of achieving efficient separation of vanadium and chromium from vanadium–chromium slag (VCS) while simultaneously tackling issues related to artificial granite waste residue (AGWR), such as its substantial stockpiling and associated air pollution. AGWR was used as a substitute calcination additive for calcium carbonate to achieve efficient separation through a calcination-leaching process. Orthogonal experiments were conducted to investigate the effects of AGWR addition amount, calcination temperature, and calcination time on the leaching behavior of vanadium and chromium. During calcination, vanadium reacts with CaO (a decomposition product of AGWR) to form acid-soluble calcium vanadate. Concurrently, chromium hydroxide decomposes into chromium oxide, which is poorly soluble in dilute acid. Subsequent leaching of the calcination product with dilute sulfuric acid leaches vanadium (V) into the solution, while chromium (Cr) remains in the residue, thus achieving separation. The experimental results showed that under the conditions of 30% AGWR addition; calcination at 850 °C for 1 h; leaching at 90 °C for 2 h with a liquid-to-solid ratio of 10:1 and a sulfuric acid concentration of 50 g·L⁻¹; the leaching rate of vanadium reached 85.68%, whereas that of chromium was only 2.34%. These results demonstrate highly efficient separation of vanadium and chromium, offering valuable insights for resource recovery from both VCS and AGWR. Full article

During the refining processes, when catalyst activity falls below acceptable levels and it is not possible to regenerate it for its reuse, the catalyst is disposed of as solid waste; however, the spent catalysts could be a promising source of metals for manufacturing new products due to their high content of heavy metals, such as nickel. In this research, nickel recovered from a spent hydrodesulfurization catalyst by ultrasonication-assisted leaching was used as a metal source for the synthesis of Ni-MOF-74 material (Ni-MOF-74E), and its properties and CO₂ adsorption capture capacity were compared with a Ni-MOF-74 prepared with commercial salt nickel nitrate (Ni-MOF-74C). The MOF-74 structure was confirmed by analytical techniques such as FT-IR and powder X-ray diffraction. By SEM and EDX, the fusiform morphology and the elemental composition were found. The CO₂ capture capacity, evaluated at 298 K, 288 K and 273 K, showed that the Ni-MOF-74E material presented an adsorption capacity higher than 2.2 mmol g⁻¹ and a heat adsorption of 44 kJ mol⁻¹. Full article

Bamboo shoots are a valuable source of dietary fiber and antioxidants; however, their high levels of soluble oxalates and uric acid require reduction prior to consumption. This study evaluated the effects of washing, soaking, and boiling on soluble oxalate content, uric acid content, antioxidant activity, and the phenolic and flavonoid profiles of bamboo shoots. Washing resulted in only slight reductions in soluble oxalates and uric acid. Prolonged soaking (7–10 h) produced more pronounced decreases, while extended boiling (60 min) was the most effective treatment, reducing uric acid and soluble oxalate levels by 86% and 89%, respectively. Processing also led to significant reductions in total phenolic content, antioxidant activity, and individual phenolic and flavonoid compounds, primarily due to leaching and thermal degradation. FTIR analysis indicated that processing mainly affected soluble components, whereas the core polysaccharide structure remained relatively stable. After selecting the optimal pretreatment, the resulting dried powders exhibited markedly reduced antinutritional factors while maintaining desirable nutritional, physicochemical, and functional properties. These findings demonstrate that processed bamboo shoot powder can be safely incorporated into food products and has strong potential as a functional ingredient for health-oriented applications. Full article

Zinc oxide nanoparticles (ZnO-NPs) have gained increasing attention across food, biomedical, environmental, and many industrial fields due to their antimicrobial properties, chemical stability, and favorable physicochemical characteristics. In parallel, enzyme immobilization on nanostructured supports has emerged as an effective strategy to enhance enzyme stability, reusability, and functional performance in biosensing and biocatalytic systems. This mini-review summarizes recent advances in the synthesis of ZnO-NPs, with emphasis on green and biogenic approaches, and examines their integration with enzymes to form ZnO-enzyme hybrid systems. Key enzyme classes, immobilization strategies, and representative applications in food quality monitoring, biosensing, and food-processing-related biocatalysis are discussed. The novelty of this article is its comprehensive and application-oriented perspective. Unlike previous reviews that primarily addressed either ZnO nanoparticle synthesis or generic enzyme immobilization, this manuscript critically integrates strategies across the full value chain, from material preparation to functional application. In addition, the review critically evaluates toxicity, migration, safety, and regulatory considerations associated with ZnO-NPs, highlighting existing knowledge gaps and the need for standardized assessment frameworks. Despite promising proof-of-concept studies, challenges related to nanoparticle reproducibility, enzyme leaching, and long-term safety remain, underscoring the need for integrated and application-oriented research to enable safe and effective implementation of ZnO-enzyme hybrid technologies in many different sectors. Full article

Micro- and nanoplastics (MNPs) are increasingly contaminating atmospheric particulates, yet their influence on PM_2.5 chemistry and toxicity remains poorly understood. This study investigates how secondary MNPs derived from common products (water bottles, coffee cups, and food plates) alter the properties of PM_2.5. We evaluated PM_2.5 leaching characteristics, oxidative potential, inflammatory activity, and bacterial-based cytological and metabolomic responses after 24 h of exposure to three MNP doses. MNPs markedly altered PM_2.5 chromophoric composition, with bottle-derived (PET) MNPs inducing the strongest increases in aromaticity, humification, and slope factor, followed by coffee cups (PLA/paper) and food plates (PP). These leaching shifts aligned with polymer-specific redox behaviors: bottle-derived MNPs enhanced antioxidant enrichment at high PM_2.5, whereas cup-derived MNPs produced the most pronounced protein-denaturation-based inflammatory activity. Escherichia coli assays showed non-linear growth responses, elevated reactive oxygen species, altered carbohydrate secretion, and membrane and protein perturbations that paralleled PM_2.5 chemical reactivity. FTIR metabolomic fingerprints revealed dose- and polymer-dependent disruptions in polysaccharide, lipid, and protein domains. Overall, the results demonstrate a mechanistic cascade in which MNP exposure reshapes PM_2.5 chemistry, amplifies oxidative and inflammatory potential, and culminates in measurable cytological and metabolic stress, with polymer identity (PET > PLA/paper > PP) as the dominant driver. Full article

This study investigated a feasible recycling and detoxification process for waste tire ash containing hazardous Zn and Al using acid leaching, followed by layered double hydroxide (LDH) synthesis. The novelty of this work is the direct conversion of a Zn/Al/Fe/Ca-rich real waste system into a phosphorus removal material, in which LDH-related uptake and secondary hydroxyapatite formation cooperatively immobilize phosphorus. Waste tire ash mainly consists of Zn, Al, Fe, Ca, and Si, most of which can be effectively leached with hydrochloric acid (HCl). The optimum leaching conditions for high extraction efficiency involved treatment with 10 M HCl for 10 min at 20 °C (solid–liquid ratio: 50 g/L). Under these conditions, the elution concentrations of Zn and Al from the residue decreased to 0.3 and 0.17 mg/L, respectively, meeting the Japanese leaching standards, whereas the raw ash showed significantly higher values. From the leached solution, LDH-containing products with high phosphorus removal capacity were synthesized at 40 °C for 2 h by adjusting the pH to 11.5. A phosphorus removal performance of 2.0 mmol/g was obtained owing to the formation of hydroxyapatite. The combined process of HCl leaching and LDH synthesis enables the detoxification of waste tire ash and the production of an environmental purification material. Full article

The environmental degradation of plastics results not only in their mechanical fragmentation into microplastics (MPs), but also in polymer main-chain scission processes, causing continuous leaching and/or volatilization of low-molecular-weight species, often characterized by a hazardous profile. In this study, we investigated the hydrophilic photooxidation products (HyPOPs) generated upon UV irradiation of polystyrene (PS) and their transformation catalyzed by the enzyme laccase from the fungus Trametes versicolor. Through a series of enzymatic tests, the enzyme was found to promote coupling and conjugation reactions of HyPOPs into poorly soluble compounds mimicking natural humic acids. The enzymatic activity of laccase was studied under different experimental conditions to simulate those found in environmental matrices. Due to their oligomeric nature, these humic acid-like products of metabolic transformation by the fungal laccase are here nicknamed “mycoplastics” (i.e., polymers from fungi). This enzymatic biodegradation and biotransformation of xenobiotic HyPOPs highlights the role of specific enzymes as biological tools for environmental self-repair of polluted ecosystems. Moreover, it opens new perspectives for remediation strategies targeting elusive micro- and nanoplastics and their continuously generated hazardous molecular degradation by-products. Humic acid-like products resulting from laccase conversion of HyPOPs could contribute to the rehabilitation of contaminated sites by promoting the removal of toxic contaminants from soil and water. Full article

The effects of storage time on the characteristics of starch in spicy strips were investigated. Techniques including differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) were employed to analyze the gelatinization properties, thermal characteristics, crystal structure, moisture distribution, and quality changes of spicy strips under different storage periods (0, 60, 120, and 180 days). The results demonstrated that prolonged storage led to a significant decrease in peak viscosity and an increase in setback value, indicating enhanced starch retrogradation. DSC analysis revealed a continuous increase in enthalpy change (ΔH), confirming the formation of more ordered double-helix structures over time. TGA revealed a shift in thermal degradation profiles, indicating changes in component interactions and moisture-binding capacity over storage. XRD patterns showed a clear transition from A-type to V-type crystals and finally to an amorphous state after 180 days. Consequently, solubility, swelling power, and amylose leaching were markedly inhibited, while the retrogradation rate of amylopectin became dominant during long-term storage. These findings provide insights into starch retrogradation mechanisms in complex snack matrices and offer guidance on mitigating quality deterioration during the shelf life of spicy strips. Full article

The electrochemical reuse of spent graphite from the negative electrodes of lithium-ion batteries is influenced by regeneration-induced changes in near-surface chemical and defect states. These states govern solid electrolyte interphase (SEI) re-formation, particularly when bulk contaminants are suppressed. Acidic malic-acid leaching and ethylenediaminetetraacetic acid chelation under alkaline conditions (pH 8.7) were compared under similar operating parameters to isolate the role of the leaching environment. This was followed by heat treatment at 1200 °C to decouple chemical cleaning from structural restoration. Both methods reduced the total impurities from 217.85 ppm to ~1.8 ppm, approaching that of commercial graphite. Despite the comparable bulk purity, depth-resolved X-ray photoelectron spectroscopy after formation cycling revealed distinct outermost surface states relevant to SEI re-formation: acidic processing yielded a more oxygenated carbon signature and higher LiOH fraction at the outermost surface (~16%), whereas alkaline chelation produced a more graphitic, carbonate-dominated surface with lower LiOH (~7%). Electrochemical and impedance measurements were consistent with these differences, suggesting that after the bulk impurities were minimized, resistance development was largely governed by the leaching-conditioned near-surface state, which biased the SEI composition. The comparison under matched conditions linked the regeneration environment to SEI-relevant surface speciation and provided a mechanistic basis for selecting regeneration routes to reuse spent graphite as a negative-electrode active material. Full article

Coal gangue represents the predominant solid waste in the coal industry and poses significant risks to both the ecological environment and human health. It has been demonstrated that recycling it in building materials effectively reduces stockpiling, mitigates environmental harm, and minimizes heavy metal leaching. However, a comprehensive review systematically focusing on the recycling of coal gangue and the behavior of its associated heavy metals in building materials is still lacking. This work introduces the physicochemical properties and environmental hazards of coal gangue, including spontaneous combustion, land occupation, and pollution risks. It also summarizes the leaching patterns, speciation, and immobilization mechanisms of heavy metals such as Cr, Cu, and Pb in gangue-based building materials, and reviews adsorption behaviors, solidification pathways, and microstructural interactions at the molecular scale. Despite ongoing efforts, over five billion tons of coal gangue remain accumulated in China, with secondary pollution from heavy metals continuing to pose serious concerns. To address these challenges, recommendations are proposed for establishing standardized leaching evaluation methods, and a novel approach for transitioning from heavy metal solidification to active utilization is introduced. This review aims to provide strategic direction for the green and sustainable recycling of coal gangue. Full article

The low activity and expansion risk of steel slag limit its large-scale utilization in cementitious systems. This study developed an alkali-sulfate synergistic activation method to prepare binder with steel slag content exceeding 50 wt%. The effects of alkali activator dosage, modulus, steel slag and flue gas desulfurization gypsum content on the mechanical properties and workability were systematically investigated. With a mix of 60% steel slag, 30% fly ash, 10% desulfurization gypsum and activated by additional 20% alkali activator with modulus 1.0, the 28-day compressive strength reached 12.85 MPa, along with excellent volume stability. Microstructural characterization revealed that the main hydration products are C-A-S-H and ettringite, which jointly form a dense microstructure. When used to solidify lead–zinc tailings for backfill, the binder yielded satisfactory strength and effectively immobilized heavy metals (Pb, As, Cd, Zn), with leaching concentrations meeting environmental standards and immobilization efficiencies > 80%. Heavy metals were primarily immobilized through physical encapsulation, ion exchange, and co-precipitation. This study elucidates the hydration and mechanisms of high-content steel slag systems under alkali-sulfate synergistic activation, providing a sustainable technical framework for large-scale utilization of steel slag and tailings management. Full article