Search Results (1,095)

Hydrometallurgy is currently the mainstream industrial process for recovering valuable components (nickel, cobalt, manganese, lithium, etc.) from spent ternary lithium-ion battery cathode materials. During the crushing of lithium batteries, cathode materials, anode materials (graphite), and electrolytes become mixed. Consequently, fluoride ions inevitably enter the leaching solution during the hydrometallurgical recycling process, with concentrations as high as 100–300 mg/L. These fluoride ions not only adversely affect the quality of the recovered precursor products but also pose environmental risks. To address this issue, this study employs a synthesized lanthanum–zirconium (La@Zr) composite material, with a specific surface area of 67.41 m²/g and a pore size of 2–50 nm, which can reduce the fluoride ion concentration in the leaching solution to below 5 mg/L, significantly lower than the 20 mg/L or higher that is typically achieved with traditional calcium salt defluorination processes, without introducing new impurities. Under optimal adsorption conditions, the lanthanum–zirconium adsorbent exhibits a fluoride ion adsorption capacity of 193.4 mg/g in the leaching solution, surpassing that of many existing metal-based adsorbents. At the same time as the valuable metals, Li, Ni, and Co, are basically not adsorbed, the selective adsorption of fluoride ions can be achieved. Adsorption isotherm studies indicate that the adsorption process follows the Langmuir model, suggesting monolayer adsorption. The secondary adsorption process is primarily governed by chemical adsorption, and elevated temperatures facilitate the removal of fluoride ions. Kinetic studies demonstrate that the adsorption process is well described by the pseudo-second-order model. After desorption and regeneration with NaOH solution, the adsorbent still has a favorable fluoride removal performance, and the adsorption rate of fluoride ions can still reach 95% after four cycles of use. With its high capacity, rapid kinetics, and excellent selectivity, the adsorbent is highly promising for large-scale implementation. Full article

Four types of phosphomolybdates (iron, cobalt, nickel, and zinc) were each combined with antimony trioxide (Sb₂O₃) to prepare polyvinyl chloride (PVC) composites. The effects of the phosphomolybdates on the combustion behavior, smoke release, and mechanical properties of the PVC composites were studied by thermogravimetric analyzer, limiting oxygen index (LOI) tester, smoke density tester, cone calorimeter, scanning electron microscopy (SEM), and universal tensile tester. The results indicate that phosphomolybdates exhibit a significant synergistic flame-retardant effect with Sb₂O₃ in the PVC matrix. Compared with Sb₂O₃ alone, the addition of phosphomolybdates can significantly improve the LOI of PVC composites. It can also reduce smoke release, lower the heat release rate (HRR) of PVC composites, and produce more char residual, which is more continuous and denser. Meanwhile, there is no significant loss of mechanical properties. Overall, nickel phosphomolybdate has been determined to be the most effective of these four phosphomolybdates. Compared with PVC-1, the peak heat release rate (PHRR) of PVC-4 with nickel phosphomolybdate decreased by 13.3%, the total smoke production (TSP) decreased by 37.3%, and the peak smoke production rate (PSPR) decreased by 28.9%. This study demonstrates that replacing some of the Sb₂O₃ with phosphomolybdate can achieve efficient flame retardancy and smoke suppression in PVC. And the results of this study can also provide a reference for future research on the application and promotion of flame-retardant PVC. Full article

Asbestos tailings represent a historical liability in many countries. Canada aims at transforming this industrial legacy into an opportunity to both mitigate the environmental footprint and recover critical (such as magnesium, nickel, chromium, and cobalt) and strategic metals, which represent significant economic development potential. This study aimed to investigate the recovery of critical and strategic metals (CSMs) from asbestos tailings using hydrochloric (HCl) acid leaching, with acid concentration (2–12 mol/L), leaching temperature (20–90 °C), and solid–liquid ratio (10–40%) as key process parameters. The tailing samples studied is composed mostly of chrysotile and lizardite. It contains about 40% magnesium (as its oxide MgO) and nickel and chromium showing contents 52 and 60 times higher than their respective average crustal abundances (Clarke values). Iron content is 8.7% (expressed as its ferric oxide Fe₂O₃). To optimize key factors influencing the leaching process, a statistical experimental design was employed. The designed leaching experiments were subsequently performed, and results were used to define leaching conditions aiming at maximizing Mg and Ni recoveries while minimizing iron contamination using response surface methodology (RSM) based on the central composite design (CCD). A quadratic polynomial model was developed to describe the relationship between the process parameters and metal recoveries. Among the tested effects of acid concentration, temperature, and pulp density on magnesium recovery, the modeling indicated that both hydrochloric acid concentration and leaching temperature significantly enhanced metal recovery, whereas increasing pulp density had a negative effect at low temperature. The empirical mathematical model derived from the experimental data, accounting for the uncertainties on chemical data, indicated that high magnesium recovery was achieved at 90 °C, with 10–12 N hydrochloric acid and a solid-to-liquid ratio of 33.6–40%. These findings reveal the potential for the recovery of critical and strategic metals, both in terms of efficiency and economic viability. Full article

Over the next 5–10 years, the feedstock to lithium-ion battery recycling facilities will shift from Co- and Ni-rich chemistries to lower-value battery chemistries, such as lithium iron phosphate (LFP). Traditional recycling processes use toxic and corrosive inorganic acids for leaching, generating toxic waste streams. The low-value feedstocks will be LFP-rich with contamination from lithium cobalt oxide (LCO) and lithium–nickel–manganese–cobalt oxide (NMC) battery chemistries. Overall, the lower-value feedstock coupled with the need to reduce environmentally damaging waste streams requires the development of robust, green leaching processes capable of selectively targeting the LFP and LCO/NMC battery chemistries. This research concluded that a first-stage oxalic acid leach could selectively extract Al, Li, and P from the industrially sourced LFP-rich black mass. When operating at the optimal conditions (0.5 M oxalic acid, 5% solids, pH 0.8, and an agitation speed of 600 rpm), >99% of the Li and P and >97% of the Al were selectively extracted after 2 h, while Mn, Fe, Cu, Ni, and Co extractions were kept relatively low, namely, at 19%, <3%, <1%, 0%, and 0%. This research also explored a second-stage leach to treat the first-stage leach residue using ascorbic acid, citric acid, and glycine. It was concluded that when leaching with glycine (30 g/L glycine, a temperature of 40 °C, an agitation speed of 600 rpm, and 2% solids at pH 9.6), that >97% of the Co, >77% of the Ni, and 41% of the Mn were extracted, while the co-extraction percentages of Cu, Fe, and Al were <27%, <4%, and <2%. Full article

Managed aquifer recharge (MAR) can address challenges pertaining to water quality and security, land subsidence, and aquifer degradation. This study has been conducted in the irrigated plains of Indus River Basin (IRB) of Pakistan, where groundwater is being used for drinking, agriculture, industries, and other commercial purposes and where the Punjab Government is implementing the MAR project. The study aims to assess the existing level of heavy metals and trace elements contamination in the groundwater and to set baseline data for the suitability of the site for the MAR project. Groundwater samples from 20 tubewells were collected from an area of 1522 km² to investigate the level of heavy metals concentration in groundwater and to assess its suitability for irrigation and drinking. Samples were analyzed for Aluminum (Al), Arsenic (As), Barium (Ba), Cadmium (Cd), Cobalt (Co), Copper (Cu), Chromium (Cr), Lead (Pb), Manganese (Mn), Molybdenum (Mo), Nickel (Ni), Selenium (Se), Strontium (Sr), and Zinc (Zn). To elucidate the contamination trend of these metals, the Heavy Metal Pollution Index (HPI), Heavy Metal Index (HI), geostatistical description, Pearson correlation analysis, and geospatial mapping were employed. Results showed that groundwater in the study area is not suitable for drinking and may pose serious health risks. It should be, however, generally suitable for irrigation. This concludes that the site is suitable for the implementation of a MAR project where the intended use of groundwater is for irrigation. It has been recommended that the groundwater may not be used for direct human consumption in the study area. It has been recommended, too, that targeted monitoring of identified hotspots and assessment of soil and crop uptake are conducted so that industrial or wastewater discharge into irrigation supplies may be prevented and controlled. For policy decisions, distinguishing irrigation suitability from potable-water safety is essential. Full article

Understanding the role of synthesis parameters in tailoring catalyst morphology is crucial for enhancing performance in electrochemical water splitting. This research systematically explores how different solvent environments affect the structural evolution and morphology of cobalt-doped nickel sulfide (Co-Ni₃S₂) nanomaterials. By systematically modifying the solvent environment using ethylene glycol and glycerol, distinct morphologies of Co-Ni₃S₂ were obtained, leading to variations in their electrocatalytic water-splitting performance. The fabricated compounds were thoroughly tested for their catalytic performance in facilitating hydrogen and oxygen evolution processes. Notably, the use of ethylene glycol as a synthesis medium led to the formation of a unique interconnected petal-like structure, significantly improving electrocatalytic activity, as evidenced by low overpotentials of 190.7 mV for HER at 10 mA cm⁻² and 414 mV for OER at 30 mA cm⁻². In contrast, when glycerol was employed as the solvent, the resulting Co-Ni₃S₂ material displayed overpotentials of 223.8 mV and 535 mV for HER and OER, respectively. Eventually, Co-doping was found to enhance the electrocatalytic performance, as pure Ni₃S₂ synthesized under the same solvent conditions exhibited higher overpotentials for both HER and OER. These findings underscore the crucial role of solvent selection in tailoring the structural and functional properties of materials for high-performance electrochemical applications. Full article

Selective depression of serpentine remains a major challenge in the flotation of low-grade nickel sulphide ores because serpentine slimes impair concentrate grade and recovery. In this study, four structurally related micromolecular depressants bearing amino and phosphonic functionalities were designed, synthesized and systematically evaluated. Micro-flotation screening (depressant range: 0–20 mg·L⁻¹) and bench-scale tests identified an operational optimum near pH 9 and a reagent dosage of ≈18 mg·L⁻¹; potassium butyl xanthate (PBX) was used as a collector and methyl isobutyl carbinol (MIBC) as a frother. Phosphonate-containing molecules (PMIDA and GLY) delivered the largest gains in pentlandite recovery and concentrate selectivity compared with carboxylate analogues and a benchmark depressant. Mechanistic studies (zeta potential, adsorption isotherms, FT-IR, and XPS) indicated that selective adsorption of amino and phosphonate groups on serpentine occurs via coordination with surface Mg sites and by altering the electrical double layer. The DLVO modelling showed that these reagents generate an increased repulsive barrier, mitigating slime coating and entrainment. Contact-angle measurements confirmed selective hydrophilization of serpentine while pentlandite remained hydrophobic. These findings demonstrate that incorporating targeted phosphonate chelation into small-molecule depressants is an effective strategy to control serpentine interference and to enhance flotation performance. Full article

Various morphologies of cobalt oxide Co₃O₄ films on cobalt (Co) foils were obtained via anodization followed by a thermal treatment at 350 °C. This study introduces a rapid and cost-effective synthesis route, achieving well-defined spinel structures in only 30 min. The novelty of this work lies in exploring nickel (Ni) as a morphological modifier in the anodization electrolyte. FESEM analysis revealed that, while anodization without Ni produced nanoflake structures, the inclusion of Ni transformed the morphology into larger cubic crystals and rice grain–shaped nanoparticles. XPS confirmed the presence of oxygen vacancies during phase formation, TEM showed spinel grains smaller than 20 nm, and Raman spectroscopy exhibited characteristic peak shifts influenced by both anodization and Ni addition. These results demonstrate that Ni not only accelerates the formation of spinel $\mathrm{C}{\mathrm{o}}_3{\mathrm{O}}_4$ but also plays a decisive role in tailoring morphology, highlighting the efficiency and novelty of this approach. Full article

The analysis of cationic surfactants with high selectivity is a source of great research interest. In this study, the absorption spectra of tetra-sulphonated metal phthalocyanine (coordinated by iron, zinc, cobalt, and nickel) in the presence of cationic surfactants in complete aqueous solutions were investigated. Interestingly, the absorption spectra of tetra-sulphonated nickel phthalocyanine (NiS₄Pc) exhibits a remarkable response to the cationic surfactants compared with other water-soluble metal phthalocyanines. Further investigation has yielded important findings that cationic surfactants with carbon chains containing twelve or more carbons cause distinct spectral responses, and the response behaviors are highly similar, showing a typical structure–activity relationship. Studies on the mechanism of response indicate that the spectral behavior could be attributed to the dramatic binding effects of structure-matched cationic surfactants on the self-association equilibrium of nickel phthalocyanine. Based on the above findings, we applied NiS₄Pc as a directly responsive optical probe for the quantitative analysis of long carbon chain cationic surfactants. Due to the high degree of similarity in optical responding, this method can be used to determine the single cationic surfactant and the total cationic surfactants. It is worth mentioning that NiS₄Pc is a water-soluble optical probe that can be used in a complete aqueous phase. Therefore, this method is not only selective but also easy and fast to operate, without the need for organic solvents. Under optimized conditions, the average calibration curve equation of the method is y = 1.66 − 0.0173 x, r = 0.9987, with a limit of detection of 3 × 10⁻⁶ mol L⁻¹. This method has been applied to the determination of real samples, for which we obtained satisfactory results. We not only describe the establishment of a new method for the direct quantitative analysis of cationic surfactants but also propose a new strategy for obtaining phthalocyanine-based optical probes in this study, which explored the novel application of phthalocyanine compounds in analytical sciences. Full article

The environmental crisis and the accelerated depletion of natural resources require strategies that balance economic growth and environmental protection in accordance with the principles of sustainable development. In this context, the mining industry, despite playing an important role in economic development, has significant negative impacts. The application of sustainable practices helps to mitigate these impacts. This study evaluates the effectiveness of rehabilitation measures applied in the abandoned mine of Punta Gorda, Cuba, using an integrated system of socio-environmental and economic indicators. The methodology, based on a procedure for socio-environmental and economic management in mine rehabilitation, comprises six stages and fourteen steps, including the valuation of ecosystem goods and services, economic valuation, and monitoring of rehabilitation results. Key results show a 5.95% improvement in economic efficiency in 2023, partial recovery of the ecosystem after rehabilitation, and improved health of mine workers. The study emphasizes the importance of multidimensional assessment tools to align mine rehabilitation with the Sustainable Development Goals (SDGs), particularly SDG 11, and highlights the role of corporate social responsibility in improving the well-being of the mining community. The proposed framework provides a replicable model for sustainable mine rehabilitation, emphasizing the integration of economic, social, and environmental indicators. Full article

Heavy metals in farmland soils pose severe threats to agricultural productivity and food safety. To investigate contamination in the soil–wheat/corn system, 24 sets of adjacent farmland soil, wheat, and corn plant samples were collected near metal smelting facilities in Jinchang City, a typical urban oasis in northwestern China. Concentrations of Ni (nickel), Cu (copper), and Co (cobalt) were measured. Results indicated mean soil concentrations of 143.66 mg kg⁻¹ (Ni), 130.00 mg kg⁻¹ (Cu), and 24.04 mg kg⁻¹ (Co), all exceeding background values for Gansu Province, confirming that the sampling sites exhibit varying degrees of contamination with Ni, Cu, and Co. Correlation analyses revealed strong intermetal relationships (Ni, Cu, Co; p < 0.01), while spatial distribution patterns showed that Ni in wheat and corn grains closely mirrored soil Ni distribution. The bio-concentration factor (BCF) for wheat roots surpassed that of corn roots, highlighting wheat’s greater susceptibility to heavy metal uptake. Heavy metal levels in crop organs exceeded limits set by the Safety Guidelines for Feed Additives. Geo-accumulation indices and potential ecological risk assessments demonstrated substantial metal accumulation and varying ecological risks, with contamination levels ranked as Cu > Ni > Co. Non-carcinogenic hazard indices indicated elevated health risks for children consuming locally grown wheat and corn. This study provides a scientific foundation for crop rotation strategies and soil remediation in the region. Full article

Near-complete (>99%) dissolution of lithium and cobalt was achieved by the leaching of black mass from spent (end-of-life) lithium-ion batteries (LiBs) using 4 M H₂SO₄ or HCl at 60 °C. Raising the temperature to 90 °C did not increase the overall extraction of lithium or cobalt, but it increased the rate of extraction. At 60 °C, 2 M H₂SO₄ or 2 M HCl performed similarly to the 4 M H₂SO₄/HCl solution, although extractions were lower using 1 M H₂SO₄ or HCl (~95% and 98%, respectively). High extractions were also observed by leaching in low pulp density (15 g/L) at 60 °C with 2 M CH₂ClCOOH. Leaching was much slower with hydrogen peroxide reductant concentrations below 0.5 mol/L, with cobalt extractions of 90–95% after 3 h. Pulp densities of up to 250 g/L were tested when leaching with 4 M H₂SO₄ or HCl, with the stoichiometric limit estimated for each test based on the metal content of the black mass. Extractions were consistently high, above 95% for Li/Ni/Mn/Cu with a pulp density of 150 g/L, dropping sharply above this point because of insufficient remaining acid in the solution in the later stages of leaching. The final component of the test work used leaching parameters identified in the previous experiments as producing the largest extractions, and just sulphuric acid. A seven-stage semi-continuous sulphuric acid leach at 60 °C of black mass from LiBs that had undergone an oxidising roast (2h in a tube furnace at 500 °C under flowing air) to remove binder material resulted in high (93%) extraction of cobalt and near total (98–100%) extractions of lithium, nickel, manganese, and copper. Higher cobalt extraction (>98%) was expected, but a refractory spinel-type cobalt oxide, Co₃O₄, was generated during the oxidising roast as a result of inefficient aeration, which reduced the extraction efficiency. Full article

The main aim of this study is to produce TEOS-based fibers using the electrospinning method with solutions without carrier polymers, unlike most TEOS-based fibers that are produced with polymer additives. This study provides fundamental insights into the production and characterization of TEOS-based fibers and offers a general overview of their potential applications. We investigate the production and overlaying of their morphological, chemical, thermal, and electrochemical properties. The effects of electrospinning parameters such as voltage, flow rate, and solution viscosity on fiber morphology were examined, revealing a strong dependence of fiber diameter and structural uniformity on these parameters. Furthermore, TEOS-based fibers containing nickel–manganese–cobalt oxide (NMC) were fabricated, and their electrochemical behavior was investigated. The analyses indicate that the addition of NMC enhances the electrochemical properties of the TEOS fibers; however, the system still requires further improvement to be effective in energy-storage applications. To investigate how the flow properties of the solution affect fiber generation during electrospinning, viscosity measurements were conducted on the TEOS-based solution. Differential thermal analysis (DTA) was applied to assess the thermal behavior and stability of the fibers at elevated temperatures. The produced fibers were analyzed using various characterization techniques. As a result, thin fibers were successfully produced. Full article

The integration of renewable energy systems and electrified transportation requires advanced energy storage solutions capable of providing both high energy density and fast dynamic response. Hybrid energy storage systems offer a promising approach by combining complementary battery chemistries, exploiting their respective strengths while mitigating individual limitations. This study presents the design, modeling, and optimization of a hybrid energy storage system composed of two high-energy lithium nickel manganese cobalt batteries and one high-power lithium titanate oxide battery, interconnected through a triple dual-active multi-port converter. A nonlinear model predictive control strategy was employed to optimally distribute battery currents while respecting constraints such as state of charge limits, current bounds, and converter efficiency. Equivalent circuit models were used for real-time state of charge estimation, and converter losses were explicitly included in the optimization. The main contributions of this work are threefold: (i) verification of the model predictive control strategy in diverse applications, including residential renewable energy systems with photovoltaic generation and electric vehicles following the World Harmonized Light-duty Vehicle Test Procedure driving cycle; (ii) explicit inclusion of the power converter model in the system dynamics, enabling realistic coordination between batteries and power electronics; and (iii) incorporation of converter efficiency into the cost function, allowing for simultaneous optimization of energy losses, battery stress, and operational constraints. Simulation results demonstrate that the proposed model predictive control strategy effectively balances power demand, extends system lifetime by prioritizing lithium titanate oxide battery during transient peaks, and preserves lithium nickel manganese cobalt cell health through smoother operation. Overall, the results confirm that the proposed hybrid energy storage system architecture and control strategy enables flexible, reliable, and efficient operation across diverse real-world scenarios, providing a pathway toward more sustainable and durable energy storage solutions. Full article

This study focuses on enhancing the efficiency of alkaline water electrolysis technology, a key process in green hydrogen production, by leveraging the synergy of magnetic fields and in situ electrode activation. Optimizing AWE efficiency is essential to meet increasing demands for sustainable energy solutions. In this research, nickel mesh electrodes were modified through the application of magnetic fields and the addition of hypo-hyper d-metal (cobalt complexes and molybdenum salt) to the electrolyte. These enhancements improve mass transfer, facilitate bubble detachment, and create a high-surface-area catalytic layer on the electrodes, all of which lead to improved hydrogen evolution rates. The integration of magnetic fields and in situ activation achieved over 35% energy savings, offering a cost-effective and scalable pathway for industrial green hydrogen production. Full article