Search Results (45)

The recalcitrance and biological toxicity of phenolic pollutants pose a serious threat to the safety of aquatic environments, and developing efficient and stable catalytic degradation technologies is a key research focus in the current environmental field. In this study, a composite material (MSN) of NH₂-MIL-101(Fe) modified by MoSe₂ nanosheets was constructed via a one-step composite strategy, aiming to address the bottlenecks of low Fe³⁺/Fe²⁺ cycling efficiency and iron ion leaching in traditional Fe-based MOFs when activating peroxymonosulfate (PMS). Characterization results showed that MoSe₂ nanosheets were uniformly dispersed on the surface of NH₂-MIL-101(Fe), and strong electronic interactions existed between them, which significantly optimized the electronic environment of active sites. MSN-3 exhibited excellent performance in activating PMS for phenol degradation: the degradation rate reached 90% within 30 min, with a k = 0.073 min⁻¹, which was much higher than that of other systems. It also showed good structural stability and cyclic regeneration ability. Mechanistic studies confirmed that the core active species in the MSN-3/PMS system are ¹O₂, •SO₄⁻ and •OH. The two-dimensional layered structure of MoSe₂ can serve as an efficient electron transport bridge to promote Fe³⁺/Fe²⁺ cycling; amino modification further optimizes the electron density of Fe active centers. The two synergistically construct a dual redox cycle of Fe³⁺/Fe²⁺ and Mo⁴⁺/Mo⁶⁺, significantly enhancing PMS activation efficiency and ¹O₂ production. This study provides a new strategy for designing Fe-MOFs-based PMS activation catalysts and also offers technical support for the practical treatment of recalcitrant organic pollutants in water. Full article

The sustainable recycling of valuable metals from spent lithium-ion batteries (LIBs) is critical for resource conservation and environmental protection but remains challenging due to the complex coexistence of target and impurity metals. This study systematically investigates the selective leaching behaviors of metals (Co, Li, Cu, Fe, Al) in phosphoric acid media, revealing that lithium could be preferentially extracted in mild acidic conditions (0.8 mol/L H₃PO₄), while complete dissolution of both Li and Co was achieved in concentrated acid (2.0 mol/L H₃PO₄). Kinetic analysis demonstrated that metal leaching followed a chemically controlled mechanism, with distinct extraction sequences: Li > Cu~Co > Fe > Al in dilute acid and Cu > Al~Li > Fe > Co in concentrated acid. Furthermore, we developed a closed-loop process wherein oxalic acid simultaneously precipitates Co/Li while regenerating H₃PO₄, enabling acid reuse with minimal efficiency loss during cyclic leaching. These findings establish a single-step phosphoric acid leaching strategy for selective metal recovery, governed by tunable acid concentration and reaction kinetics, offering a sustainable pathway for LIBs recycling. Full article

Environmental sustainability and responsible resource utilization are critical global challenges. In this work, we present a sustainable and circular-economy-based approach for synthesizing CuFe₂O₄ nanoparticles by directly utilizing copper oxide minerals sourced from Chilean mining operations. Copper sulfate (CuSO₄) was extracted from these minerals through acid leaching and used as a precursor for nanoparticle synthesis via both chemical co-precipitation and microwave-assisted methods. The influence of different precipitating agents—NaOH, Na₂CO₃, and NaF—was systematically evaluated. XRD and FESEM analyses revealed that NaOH produced the most phase-pure and well-dispersed nanoparticles, while NaF resulted in secondary phase formation. The microwave-assisted method further improved particle uniformity and reduced agglomeration due to rapid and homogeneous heating. Electrochemical characterization was conducted to assess the suitability of the synthesized CuFe₂O₄ for supercapacitor applications. Cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) measurements confirmed pseudocapacitive behavior, with a specific capacitance of up to 1000 F/g at 2 A/g. These findings highlight the potential of CuFe₂O₄ as a low-cost, high-performance electrode material for energy storage. This study underscores the feasibility of converting primary mined minerals into functional nanomaterials while promoting sustainable mineral valorization. The approach can be extended to other critical metals and mineral residues, including tailings, supporting the broader goals of a circular economy and environmental remediation. Full article

Plastic recycling, especially of polyethylene terephthalate (PET), is essential for reducing plastic waste and promoting sustainability. This study examines the migration of phthalic acid esters (PAEs) from locally sourced recycled PET (rPET) bottles under high-temperature conditions (24 °C, 50 °C, and cyclic 70 °C) over a period of three weeks. High-Performance Liquid Chromatography (HPLC) analysis revealed increased PAE leaching at elevated temperatures, though levels remained below international safety limits. Thermo-Gravimetric Analyzer (TGA) confirmed that plastic caps exhibit higher thermal stability and decompose more completely than plastic bottles under various thermal conditions, highlighting the influence of material composition and thermal aging on degradation behavior. Findings highlight the importance of proper storage and ongoing monitoring to ensure consumer safety. Future research should investigate alternative plasticizers to improve the safety of PET recycling. Full article

This study investigates the effectiveness of geopolymer-based binders for the stabilization of silty sand, aiming to improve its strength and durability under cyclic environmental conditions. A composite binder consisting of Ground Granulated Blast-furnace Slag (GGBS) and Recycled Glass Powder (RGP), modified with nano poly aluminum silicate (PAS), was used to treat the soil. The long-term performance of the stabilized soil was evaluated under cyclic wetting–drying (W–D) conditions. The influence of PAS content on the mechanical strength, environmental safety, and durability of the stabilized soil was assessed through a series of laboratory tests. Key parameters, including unconfined compressive strength (UCS), mass retention, pH variation, ion leaching, and microstructural development, were analyzed using field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS). Results revealed that GGBS-stabilized specimens maintained over 90% of their original strength and mass after eight W–D cycles, indicating excellent durability. In contrast, RGP-stabilized samples exhibited early strength degradation, with up to an 80% reduction in UCS and 10% mass loss. Environmental evaluations confirmed that leachate concentrations remained within acceptable toxicity limits. Microstructural analysis further highlighted the critical role of PAS in enhancing the chemical stability and long-term performance of the stabilized soil matrix. Full article

Pyrrolizidine alkaloids are plant-derived toxins with environmental persistence and the potential to contaminate soil, water, and adjacent crops. This study investigated the leaching behavior and environmental fate of PAs from two PA-producing weeds—Myosotis arvensis L. (Boraginaceae) and Senecio vulgaris L. (Asteraceae)—in two Latvian agricultural soils: sandy loam and loam. Hot- and cold-water plant extracts were applied to soil columns (10 cm and 20 cm), and leachates were analyzed over a 14-day period using QuEChERS purification and LC-HRMS detection. Leaching varied by plant species, extract type, and soil. M. arvensis showed significantly higher cumulative leaching (77–84% for cold, 65–71% for hot extracts), attributed to the higher solubility of N-oxides. In contrast, S. vulgaris extracts leached minimally (<0.84% from sandy loam) and were undetectable in loam. The presence of cyclic diester PAs in S. vulgaris and the higher cation exchange capacity of loam favored retention or degradation. PANO-to-PA conversion occurred in both soils, indicating redox activity. The fate of PAs was influenced by structural type (diesters showing higher persistence), extraction method (hot extraction releasing more pyrrolizidine alkaloids), and soil properties such as pH, organic matter, and cation exchange capacity, which affected sorption and mobility. These findings underscore the significance of soil composition in controlling PA mobility and associated environmental risks. Future research should focus on long-term PA persistence across diverse soil types and investigate crop uptake potential and microbial degradation pathways under field conditions. Full article

To overcome the low extraction efficiency and environmental concerns associated with traditional vanadium extraction methods, this study proposes an innovative nitric acid oxygen pressure leaching approach integrated with nitrogen recycling. Through systematic single-factor experiments and response surface optimization, key parameters, including nitric acid concentration, leaching temperature, liquid-to-solid ratio, and total pressure, were carefully evaluated and optimized. Under optimal conditions, consisting of 1.5 mol/L nitric acid, a temperature of 127.43 °C, a liquid-to-solid ratio of 5 mL/g, and a total pressure of 2 MPa, the vanadium leaching efficiency reached 73.1%. Cyclic leaching experiments confirmed the feasibility of nitrogen recycling. Characterization analyses by SEM-EDS, XRD, BET, and FTIR revealed that nitric acid oxygen pressure leaching significantly disrupted the mineral lattice structure, altering the coordination environment of metal ions and increasing surface porosity, thereby facilitating efficient vanadium dissolution from stone coal. This study provides valuable insights and establishes a scientific foundation for developing efficient, environmentally friendly, and economically viable vanadium extraction techniques from low-grade stone coal resources, thereby contributing to sustainable mining practices and resource utilization. Full article

Salt caverns serve as underground storage for crude oil, natural gas, compressed air, carbon dioxide, and hydrogen. Key stages of cavern development for storage purposes include design, construction, storage, and abandonment. The design phase addresses optimal cavern shape, size, pillar dimensions, number of caverns, the impact of interbeds, and cyclic loading while considering the creep behavior of salt and the mechanical behavior of surrounding layers. During this phase, geological factors such as depth, thickness, and the quality of salt are considered. For construction, two main methods—direct leaching and reverse leaching—are chosen based on design specifications. The storage stage includes the injection and withdrawal of gases in a cyclic manner with specific injection rates and pressures. After 30 to 50 years, the caverns are plugged and abandoned. The geological limitation of salt domes makes it essential to look for more bedded evaporites. This study provides a comprehensive review of bedded evaporites, including their origin and depositional environment. The stability of caverns in all these stages heavily relies on geomechanical analysis. Factors affecting the geomechanics of bedded salts such as mineralogy, physical properties, and mechanical properties are reviewed. A list of bedded evaporites in the U.S. and Canada, including their depth, thickness, and existing caverns, is provided. Additionally, this study discusses the main geomechanical considerations influencing design, solution mining, cyclic loading, and abandonment of caverns in bedded salt caverns. Full article

In this study, the selective separation of copper ions (Cu²⁺) from leaching solutions containing both Cu²⁺ and nickel ions (Ni²⁺) was investigated using electrolysis cells with high convection (Chemelec). Firstly, the electrochemical behavior of solutions containing only single Cu²⁺, single Ni²⁺, and both Cu²⁺ and Ni²⁺ was investigated using cyclic voltammetry (CV). Cu²⁺ reduction was observed at −0.15 V in solutions that contained either simply Cu²⁺ or a Cu²⁺-Ni²⁺ combination, whereas oxidation happened at 0.17 V in a single step. The CV analysis of a Ni²⁺-containing solution at pH 1 revealed that Ni²⁺ was not reduced. Potentiostatic selective Cu²⁺ reduction experiments were conducted at cathode potentials of −0.3 V, −0.4 V, and −0.5 V. Increasing the potential from −0.3 V to −0.5 V enhanced copper recovery from 84% to 94%. The current efficiency remained above 90% across all three potentials during 3 h experiments. At −0.5 V, extending the experiment time from 3 h to 5 h resulted in copper recovery exceeding 99%, while current efficiency declined from 90% to 80%. The cathode products were analyzed using X-ray diffraction (XRD), revealing that the main phase consisted of metallic copper. Full article

Peroxynitrite-based advanced oxidation technology has gradually become a research hotspot for degrading dye wastewater due to its high efficiency and environmentally friendly features. Transition metal elements, which are commonly used as catalysts for the activation of persulfates, suffer from problems such as easy deactivation and leaching of metal ions, which limit their practical application. In this study, Co₇₈Si₈B₁₄/g-C₃N₄ composite catalysts were prepared by wet milling and ball milling methods to investigate their degradation of Orange II dyes by assisting the activation of peroxynitrite under visible light, and the effects of the catalyst ratio, light intensity, and the dosage of catalysts on the degradation performance were investigated. It was shown that the optimum ratio of Co₇₈Si₈B₁₄ to g-C₃N₄ was 1:3, and the reaction rate constants for the degradation of orange dye by Co₇₈Si₈B₁₄/g-C₃N₄ + PMS + VIS were 4.3 and 5.37 times higher than those of single g-C₃N₄ + PMS and Co₇₈Si₈B₁₄ + PMS, respectively. Meanwhile, the composite catalyst also showed good degradation performance for rhodamine B, methyl orange, and methylene blue dyes, and the degradation effect could reach more than 75%. Cyclic stability tests showed that the catalyst maintained a high degradation efficiency of more than 94% over multiple cycles with low ion dissolution concentration. Its high catalytic activity is attributed to the lowest adsorption energy of the composite catalyst to PMS (E_ads = −1.97 eV), which facilitates the degradation reaction, while the synergistic effect of g-C₃N₄ and Co₇₈Si₈B₁₄ promotes the production of ·SO₄, ·OH, and ·O²⁻. This study provides new ideas for the development of stable and efficient catalysts to expand the synergy between PMS-based and other advanced oxidation technologies. Full article

Peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) relying on non-radical pathways offer advantages such as resistance to interference, efficient oxidant utilization, and selective degradation of pollutants. In this study, an Fe, N co-doped activator (Fe-N-C_1.5) was synthesized using a simple mixed solvent pyrolysis method. The Fe-N-C_1.5 exhibited excellent PMS activation activity. A total of 100% of paracetamol (PCT, 10 ppm) was degraded in the Fe-N-C_1.5/PMS system in 7 min. Furthermore, this oxidation system maintained effective PCT removal even in the presence of background ions and in real water matrices. In addition, the leached Fe concentration after 60 min was only 0.084 mg/L, and 94% of PCT could still be removed during the fourth cyclic use of the catalyst. Quenching experiments, electron paramagnetic resonance (EPR), and electrochemical analysis revealed that the Fe-N-C_1.5/PMS/PCT system predominantly relies on non-radical pathways, including singlet oxygen (¹O₂) and catalyst-interface-mediated electron transfer process (ETP). X-ray photoelectron spectroscopy (XPS) analysis and KSCN toxicity experiment confirmed that the graphitic N, carbonyl (C=O), and Fe-N_x were the main PMS activation sites. This study provides an understanding of degradation mechanisms of the Fe-N-C_1.5/PMS/PCT system and offers insights into the design of iron–carbon composite catalysts that carry out non-radical PMS activation. Full article

Efficient extraction of zinc from polymetallic concentrates is crucial for the metallurgical industry. Traditional leaching techniques often rely on strong oxidizing agents, which can be wasteful and environmentally harmful. While cyclic oxidation systems like the Fe³⁺/Fe²⁺ pair are known, they often fail to achieve high leaching rates, especially when the raw material contains multiple sulfide minerals. In this study, we developed a novel oxidation system using manganese dioxide (MnO₂) as the primary oxidizing agent and potassium iodide (KI) as a supporting material to create an I₂/I⁻ oxidation cycle in a sulfuric acid medium, at an atmospheric pressure between 40 °C and 80 °C. Leaching experiments were conducted under varying temperatures and KI doses. The results demonstrated that for the MnO₂-KI system, a zinc leaching degree of 89.78% was achieved after 3 h of leaching at 80 °C, and kinetic studies indicated that the leaching process is diffusion-controlled (through the thin film), with an activation energy of 27.65 kJ mol⁻¹. Moreover, this system offers an improved method for separating iodine from the leachate upon completion, enhancing the overall process efficiency. It also opens opportunities to test other primary oxidizing agents in combination with iodide salts. These findings suggest that the MnO₂-KI oxidation system offers a promising approach for improving zinc recovery from sphalerite concentrates. Full article

Phosphorus (P) pollution is a leading cause of water eutrophication, and metal-modified biochar is an effective adsorbent with the ability to alter the migration capacity of phosphorus. This study uses bamboo as the raw material to prepare metal-modified biochar (ZFCO-BC) loaded with Fe and Ca under N₂ conditions at 900 °C, and investigates its adsorption characteristics for phosphate. Batch experimental results show the adsorption capacity of the ZFCO-BC gradually increases (from 4.0 to 69.1 mg/g) as the initial phosphate concentration increases (from 2 to 900 mg/L), mainly through multilayer adsorption. Additionally, as the pH increases from 1 to 7, the adsorption capacity of the ZFCO-BC climbs to reach its maximum value of 48.4 mg/g with an initial phosphate concentration of 150 mg/L. At this pH, phosphate primarily exists as H₂PO₄⁻ and HPO₄²⁻, which both readily react with Fe³⁺ and Ca²⁺ in the biochar. Furthermore, the addition of CO₃²⁻, HCO₃⁻, NO₃⁻, SO₄²⁻, F⁻, and Cl⁻ each affect the removal rate of phosphate by less than 10%, indicating the ZFCO-BC has a highly efficient and selective phosphate adsorption capacity. A multi-column adsorption experiment designed to achieve long-term and efficient phosphorus removal treated 275.5 pore volumes (PVs) of water over 366 h. The cyclic adsorption–desorption experiment results show that 0.5 M NaOH can effectively leach phosphate from the ZFCO-BC. Observations at the molecular level from P K-edge XANES spectra confirm the removal of low-concentration phosphate is primarily dominated by electrostatic attraction, while the main removal mechanism for high-concentration phosphate is chemical precipitation. This study demonstrates that ZFCO-BC has broad application prospects for phosphate removal from wastewater and as a potential slow-release fertilizer in agriculture. Full article

This study presents an innovative approach to utilize coal gasification coarse slag (CGCS) for efficient and low-cost gallium extraction. Using a one-step acid leaching process, mesoporous silica with a surface area of 258 m²/g and a pore volume of 0.15 cm³/g was synthesized. The properties of CGCS before and after acid leaching were characterized through SEM, FTIR, XRD, and BET analyses, with optimal conditions identified for maximizing specific surface area and generating saturated silanol groups. The prepared mesoporous silica demonstrated a 99% Ga(III) adsorption efficiency. Adsorption conditions were optimized, and adsorption kinetics, isotherms, and competitive adsorption behaviors were evaluated. Competitive adsorption with vanadium suggests potential application in Ga(III) extraction from vanadium-rich waste solutions. Furthermore, the recyclability of both the acid and adsorbent was explored, with the adsorbent maintaining over 85% adsorption efficiency after five cycles. The adsorption mechanism was further elucidated through SEM-EDS, XPS, and FTIR analyses. This work not only advances resource recovery from industrial waste but also offers a sustainable method for gallium extraction with industrial applications. Full article

The growing adoption of lithium iron phosphate (LiFePO₄) batteries in electric vehicles (EVs) and renewable energy systems has intensified the need for sustainable management at the end of their life cycle. This study introduces an innovative method for recycling lithium from spent LiFePO₄ batteries and repurposing the recovered lithium carbonate (Li₂CO₃) as a carbon dioxide (CO₂) absorber. The recycling process involves dismantling battery packs, separating active materials, and chemically treating the cathode to extract lithium ions, which produces Li₂CO₃. The efficiency of lithium recovery is influenced by factors such as leaching temperature, acid concentration, and reaction time. Once recovered, Li₂CO₃ can be utilized for CO₂ capture in hydrogen purification processes, reacting with CO₂ to form lithium bicarbonate (LiHCO₃). This reaction, which is highly effective in aqueous solutions, can be applied in industrial settings to mitigate greenhouse gas emissions. The LiHCO₃ can then be thermally decomposed to regenerate Li₂CO₃, creating a cyclic and sustainable use of the material. This dual-purpose process not only addresses the environmental impact of LiFePO₄ battery disposal but also contributes to CO₂ reduction, aligning with global climate goals. Utilizing recycled Li₂CO₃ decreases the demand for virgin lithium extraction, supporting a circular economy. Furthermore, integrating Li₂CO₃-based CO₂ capture systems into existing industrial infrastructure provides a scalable and cost-effective solution for lowering carbon footprints while securing a continuous supply of lithium for future battery production. Future research should focus on optimizing lithium recovery methods, improving the efficiency of CO₂ capture, and exploring synergies with other waste management and carbon capture technologies. This comprehensive strategy underscores the potential of lithium recycling to address both resource conservation and environmental protection challenges. Full article