Search Results (103)

Although previous reviews of electroless nickel-based coatings have focused separately on deposition, coating performance or prediction methods, a thorough review that concurrently discusses the input process variables, output performance variables, performance prediction techniques and optimization strategies remains unaddressed. This study aims to provide a comprehensive review of the available literature on the performance prediction and optimization of electroless nickel-based coating, focusing on substrate types, coating types, input process variables, output performance variables, prediction methods and optimization techniques, including their strengths and weaknesses. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology was used for the screening and selection phases of the study. Considering 32 studies, the most commonly employed input process variable and output performance variable were reducing agent concentration (24 studies) and microhardness of the coatings (10 studies) respectively. Real-world problems generally involve multiple output variables, but most prediction models were single-output. The majority of previous studies (15 studies) employed Artificial Neural Network (ANN) prediction models, which are black-box methods, limiting optimization due to their inability to generate explicit mathematical equations. Despite requiring predefined experimental designs, Response Surface Methodology (RSM) was the most widely used optimization strategy, accounting for 11 reviewed studies. This review guides researchers in establishing their study objectives and future research directions by addressing research gaps in the reviewed articles. Full article

The increasing demand for lithium-ion batteries (LIBs) raises concerns about the security of critical raw material supply and the management of hazardous waste. Efficient recycling can alleviate these issues by transforming spent batteries into high-value secondary materials for the circular economy. Industrial recycling has traditionally focused on the recovery of nickel (Ni) and cobalt (Co), whereas lithium (Li) recovery has often been sidelined due to technical complexities and fluctuating economic incentives. To meet the European Union (EU) Batteries Regulation target of 80% lithium recovery by the end of 2031, technically effective and economically viable lithium recovery strategies are required. This study investigates the use of food-grade sucrose as an organic reductant for the targeted recovery of lithium from NMC622 and NCA battery materials. The process combines sucrose-assisted reductive roasting with selective water leaching. The effects of roasting temperature, holding time, sucrose dosage, and heating rate were systematically evaluated and optimised. Under the best conditions of 600 °C, 15 min, 15 wt% sucrose, and a heating rate of 20 °C/min, lithium leaching efficiencies of 93.2% and 87.6% were achieved for separated NMC622 cathode material and NMC622-derived black mass, respectively. The method was also applicable to NCA-based black mass, reaching 83.7% lithium recovery under the same conditions. Mechanistic analysis revealed that lithium release was strongly controlled by the extent of transition metal reduction. Cobalt was fully reduced to its metallic state under all tested conditions. However, maximum lithium recovery required nickel to be reduced to metallic Ni and manganese-containing phases to be converted to MnO. The sucrose-assisted roasting process was rapid and holding times longer than 15 min decreased lithium recovery. This decrease was caused by the formation of poorly soluble lithium-containing phases, such as LiF and Li₃PO₄. F composition analysis showed the black mass (1.06 wt%) and anode fractions (2.26 wt%) to contain significantly more F than the cathode fraction (0.46 wt%), hence leading to the 5% Li leaching efficiency difference between cathode and black mass fractions under most conditions tested. Overall, these results demonstrate that sucrose-assisted reductive roasting, followed by selective water leaching, provides a rapid and effective route for high-efficiency lithium recovery from NMC- and NCA-based battery materials. Full article

The blue, white, and black glazed areas of nineteen Nevers earthenware pieces bearing a date or precisely datable between 1589 and 1865 were for the first time analyzed by X-ray fluorescence spectroscopy at the Musée de la faïence et des Beaux-Arts-‘Frédéric Blandin’ in the city of Nevers by pXRF in order to categorize the raw materials and recipes used. The semi-quantitative signal comparison of major elements and impurities such as rubidium, strontium and zirconium shows the use of the same raw materials except for six artifacts. At least three types of cobalt, characterized by association with copper, nickel, and manganese, are observed. Different blacks (with manganese or bismuth) are observed. A comparison is made between the classification obtained with chemometry (z-score, PCA, and dendrograms of similarity) and a reasoned analysis of ternary diagrams based on the signal of the most characteristic elements. This preliminary work demonstrates the potential provided for the categorization of enameled ceramics and their dating through non-invasive on-site semi-quantitative elemental analyses. No important advantages were observed for the chemometric procedure: the same conclusions are obtained by quantitative comparisons of the XRF data, but the chemometric procedures allow a clear visualization of the main conclusions. Full article

Fine particulate matter (PM_2.5) composition, rather than mass alone, plays a critical role in determining toxicity and health impact. This study examined short-term associations between daily PM_2.5 constituents—black carbon (BC), nitrate (NO₃⁻), ammonium (NH₄⁺), and trace elements—and cardiopulmonary hospital admissions in Makkah, Saudi Arabia. Twelve months of constituent data from the Alharam monitoring site were linked to Herra hospital admissions for cardiovascular (CVD) and pulmonary diseases, stratified by visit type, age, and sex. Negative-binomial generalized linear models estimated adjusted relative risks (aRRs) per interquartile range increase in each constituent, controlling for meteorology, seasonality, and temporal trends. Mean PM_2.5 was 113.6 µg/m³; BC, sulfur, NO₃⁻, and NH₄⁺ dominated the fine fraction. Crustal elements were strongly intercorrelated (r > 0.9), while BC, lead (Pb), and nickel (Ni) showed moderate correlations (r ≈ 0.4–0.6), suggesting shared anthropogenic origins. BC increased CVD emergency/outpatient visits by 18% (aRR = 1.18; 95% CI: 1.08–1.29) and inpatient admissions by 25% (aRR = 1.25; 95% CI: 1.07–1.46). Ni and sulfur were also significant predictors; crustal elements were not. Multi-pollutant models confirmed BC and Pb as independent predictors (aRR = 1.19; 95% CI: 1.02–1.38). Effects were strongest among older adults aged 45–65 at lag 0–2 days. These findings highlight the need for emission controls targeting traffic and industrial combustion sources. Full article

Biohydrometallurgical processing of spent lithium-ion batteries offers a low-impact route for critical metal recovery compared with conventional hydrometallurgy. In this work, the iron-oxidizing bacterium Acidithiobacillus ferrooxidans was evaluated for the bioleaching of cobalt (Co), nickel (Ni), lithium (Li) and copper (Cu) from pyrolyzed industrial black mass derived primarily from LiCoO₂-based batteries, containing both LiCoO₂ and LiNiO₂ layered oxide phases. Batch experiments were conducted in 9K medium at 30 °C, varying pulp density (1%–2%, w/v), inoculum volume (10–20 mL in 200 mL medium) and initial pH (with and without adjustment). At 1% pulp density and 10% v/v inoculum, metal recoveries after 6–7 days reached about 64%–70% Co, 57%–72% Ni, 52%–60% Li and 81%–100% Cu, with most dissolution occurring in the first 6 days. Higher inoculum loads without initial pH adjustment increased Li recovery up to 79%, but did not further improve Co and Cu, indicating a trade-off between microbial activity, metal toxicity and ferric iron availability. The temporal evolution of pH and metal dissolution is consistent with indirect redoxolysis by biogenic Fe³⁺ and sulfuric acid generated during ferrous iron and elemental sulfur oxidation. Overall, the results confirm the feasibility of A. ferrooxidans-assisted bioleaching as a green option for Co, Ni, Li and Cu recovery from spent LiCoO₂ batteries and provide operating windows for subsequent process optimization and scale-up. Full article

Black shale represents a distinctive and critical mineral resource in China, harboring approximately 90% of the nation’s recoverable vanadium reserves while concurrently containing abundant strategic metal elements such as nickel and molybdenum. However, the complex occurrence states of vanadium, nickel, and molybdenum within black shale pose significant challenges to their efficient extraction. Conventional metallurgical processes—including calcination-leaching and hydrometallurgical leaching—primarily target vanadium recovery, exhibiting limited efficiency for comprehensive utilization of valuable metals. Against the backdrop of green metallurgy and carbon neutrality objectives, bioleaching techniques have garnered extensive research attention. This study developed a specialized consortium of ore-leaching microorganisms, designated WZ-Q, tailored to the mineralogical characteristics of black shale, demonstrating effective leaching capabilities for vanadium, nickel, and molybdenum. Furthermore, the enhancing effects of Fe²⁺, elemental sulfur (S⁰), and pyrite as energy substrates on bioleaching efficiency were investigated. Upon incorporating these energy materials, maximum leaching efficiencies reached 66.5% for vanadium, 82.5% for nickel, and 29.7% for molybdenum. Analysis through leaching process monitoring and multi-characterization of both raw ore and residues revealed that supplemental energy substrates intensify shifts in solution potential and pH, thereby promoting elemental oxidation and mineral decomposition. Nevertheless, critical impediments to leaching efficiency include the encapsulation of target elements within silicate matrices and incomplete dissolution of oxidized species. Subsequent research should prioritize methodologies to intensify silicate mineral dissolution and enhance the release of oxidized compounds during microbial leaching processes. Full article

The growing demand for lithium-ion batteries (LIBs) is driving a rapid increase in the volume of spent cells which—as hazardous waste—must be managed effectively in accordance with circular-economy principles. Hydrometallurgical recycling allows the recovery of critical metals at far lower environmental cost than primary mining. This paper presents a method for obtaining metallic nickel from sulfate leach solutions produced by leaching the so-called “black mass” derived from shredded LIBs. Nickel electrodeposition was performed on a stainless-steel cathode with Ti/Ru-Ir anodes at 60 °C and pH 3.0–4.5. Two process variants were examined. Variant A—with a decreasing Ni²⁺ concentration (49 → 25 g L⁻¹)—achieved a current efficiency of 60–88%, but the deposits were non-uniform and prone to flaking. Variant B—in which the bath was stabilized by the continuous dissolution of Ni(OH)₂ (maintaining Ni²⁺ at 35–40 g L⁻¹) and amended with PEG-4000, H₃BO₃ and Na₂SO₄—reached higher efficiency (78–93%) and produced uniform, bright deposits up to 0.5 mm thick with a purity >90%. The results confirm that keeping the nickel concentration constant and appropriately modifying the electrolyte significantly improve both the qualitative and economic aspects of recovery, highlighting electrolysis as an efficient way to process LIB waste and close the nickel stream within the material cycle. Full article

This study investigated the solvent extraction of a high-nickel-content metal solution using nickel-preloaded extractants. A synthetic high-nickel lithium-ion battery (LIB) black mass leachate was prepared to extract Cu, Al, and Mn using Ni-preloaded D2EHPA (Ni-D2EHPA). Then, Co was extracted from the raffinate using Ni-preloaded PC88A (Ni-PC88A). The results showed that Ni-preloaded D2EHPA extracted more than 99% of the Al, Cu, and Mn. Co was also co-extracted at a rate of 53%, but 99% of the Co was scrubbed with 0.2 M H₂SO₄. Co was extracted from the raffinate using Ni-PC88A at a rate of 99% with 1.0 O/A. Finally, 99% of the Co in the organic phase was stripped using 2.0 M sulfuric acid. After Co extraction using Ni-PC88A, 80 g/L Ni and 1.38 g/L Li remained in the raffinate. Crude nickel sulfate was produced from the raffinate after precipitation of Li as lithium carbonate. Full article

Lithium-ion batteries are essential to ensure electric mobility and reduce CO₂ emissions from transportation. One of the most commonly used chemistries is nickel–cobalt–manganese (NMC) batteries, which also have applications beyond the automotive sector. The recycling of these batteries requires the development of technologies to enable the selective separation and recovery of the metals present in the battery. One of these selective technologies involves the use of deep eutectic solvents (DESs). This research study investigates the different parameters that influence the recovery of Co(II) from hydrochloric acid medium using the deep eutectic solvent 3 Aliquat 336:7 L-Menthol. Firstly, using synthetic Co(II) solutions, the parameters influencing the cobalt extraction process are examined, and then these optimal conditions are applied to the recovery of cobalt from solutions obtained by dissolving NMC 622 battery black mass in 10 M HCl. The obtained results show that the DES used is highly selective for Co(II) recovery compared to other metals present in the solution (Ni, Li and Mn), achieving recoveries of up to 90% of the cobalt initially present in solution. Stripping with H₂SO₄ 0.5 M allows the recovery of cobalt as a crystalline monohydrate salt (CoSO₄.H₂O). The optimization of the Co/Cu separation conditions is carried out, achieving the separation of Cu(II) using Aliquat 336 in kerosene. 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

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 growing demand for lithium-ion batteries (LIBs) requires efficient and sustainable recycling solutions. This study investigates bioleaching as an alternative to conventional hydrometallurgical methods, focusing on (i) organic acid-mediated leaching with Gluconobacter oxydans and (ii) sulfuric acid bioleaching with Acidithiobacillus thiooxidans. Experiments were conducted at 26 °C with leaching durations of one to three weeks, depending on the microbial system, at pH 1.35 for sulfuric acid treatments, and with liquid-to-solid ratios equivalent to 100 mL g⁻¹ (A. thiooxidans) or 100 mL g⁻¹ in culture medium (G. oxydans). Results show that indirect bioleaching with G. oxydans achieved high recovery rates for cobalt (96%), manganese (100%), nickel (65%), and lithium (68%), while the direct approach was less effective due to microbial inhibition by black mass components. Similarly, biologically produced sulfuric acid exhibited moderate leaching efficiencies, but chemically synthesized sulfuric acid outperformed it, particularly for nickel (93%) and lithium (76%) after one week of leaching. These findings suggest that bioleaching is a promising, eco-friendly alternative for LIB recycling but requires further process optimization to improve metal recovery and industrial scalability. Future research should explore hybrid approaches combining bioleaching with conventional leaching techniques. Full article

Harnessing solar energy is crucial for applications such as water desalination through solar collectors, where efficient conversion of solar radiation into thermal energy is required. In this study, electroless nickel–phosphorus (Ni-P) coatings and their carbon black (CB) nanoparticle composites were successfully deposited and evaluated as selective solar absorbers. The coatings exhibited compact, crack-free, and amorphous structures composed mainly of Ni(OH)₂ and NiOOH, as confirmed by SEM-EDS, XRD, FTIR, and Raman analyses. Increasing the pH enhanced the deposition rate and coating thickness while reducing the phosphorus content. Incorporation of CB nanoparticles was confirmed, though it slightly decreased coating thickness. Optical characterization revealed high absorptance and low emissivity across all samples, with the Ni-P coating produced at higher pH (C1) achieving the best performance (brightness L* = 29.0; figure of merit α − ε = 0.84). Aging tests further demonstrated the resilience of this sample, maintaining a figure of merit of 0.81. These findings establish Ni-P coatings, particularly at higher pH, as promising and safer alternatives to conventional chromium-based solar selective coatings. Full article

A novel voltammetric sensor was constructed by modifying a glassy carbon electrode with a composite material consisting of platinum–nickel-doped tin oxide and carbon black (PtNiSnO₂-CB/GCE), enabling highly sensitive differential pulse voltammetry (DPV) determination of trazodone HCl (TRZ). The DPV experimental parameters, including the composition of the supporting electrolyte and instrumental settings, were carefully optimized to achieve maximum analytical efficiency. Within the linear range of 1–10 µM, quantification of TRZ molecules could be performed without the preconcentration step. When applying a 60 s accumulation time (in the range 0.02–0.2 µM of TRZ), the detection limit reached 4.1 nM (1.67 mg L⁻¹), indicating superior sensitivity compared to previously reported voltammetric techniques. The method demonstrated good reproducibility, with a relative standard deviation of 4.3% for 10 repeated measurements at 0.06 µM TRZ. The developed sensor exhibits excellent stability, simplicity of fabrication, and operational convenience. Its practical applicability was confirmed by the successful analysis of molecules of TRZ in diverse sample types, including pharmaceutical products, urine, plasma, river water, and artificial gastric and intestinal fluids, with recovery rates between 97.7% and 104.2%. Flow injection analysis (FIA) with amperometric detection was also performed for TRZ molecule determination. Full article

In this study, a selection of active materials were coated onto commercially available intermediate modulus carbon fibers to form and analyze the performance of novel composite cathodes for structural power composites. Various slurries containing polyvinylidene fluoride (PVDF), active material powders, 1-methyl-2-pyrrolidone (NMP) and carbon black (CB) were used to coat carbon fiber tows by immersion. Four active materials—lithium cobalt oxide (LCO), lithium iron phosphate (LFP), lithium nickel manganese cobalt oxide (NMC), and lithium nickel cobalt aluminum oxide (NCA)—were individually tested to assess their electrochemical reversibility. The cells were prepared with a polymer separator and liquid electrolytes and assembled in 2025-coin cells. Electrochemical analysis of the cathode materials showed that at C/5 and room temperature the measured capacities ranged from 39.8 Ah kg⁻¹ to 64.7 Ah kg⁻¹ for the LFP and NCA active materials, respectively. The full cells exhibited capacities of 18.1, 23.5, 27.2, and 28.2 Ah kg⁻¹ after 55 cycles for LFP, LCO, NCA, and NMC811, respectively. Finally, visual and elemental analysis were performed via scanning electron microscope (SEM) and energy-dispersive x-ray (EDX) confirming desirable surface coverage and successful transfer of the active materials onto the carbon fiber tows. Full article