Spent nickel–metal hydride (Ni–MH) batteries have attracted significant interest due to their high content of valuable metals. In this study, we propose an environmentally friendly thiosulfate leaching system that uses sodium thiosulfate (Na2S2O3) and copper sulfate (CuSO4) in combination to efficiently extract nickel (Ni), cobalt (Co), and rare earth metals (RE) from the electrode materials of spent Ni–MH batteries. Under the catalytic oxidation effect of Cu2+, the efficient and synergistic effective leaching of these valuable metals has been achieved. The experimental results indicate that the leaching efficiencies of Ni, Co, and RE reached 92.53, 95.91, and 98.95%, respectively. Kinetic analysis revealed that the leaching process of Ni was controlled by chemical reactions, whereas the leaching of Co and RE was governed by a mixed control. Moreover, we demonstrate a “waste-to-wealth” strategy by repurposing the sulfur-rich leaching residue as an effective photo-Fenton catalyst, achieving degradation efficiencies of 92.52% for Rhodamine B (RhB) and 70.58% for Methyl Orange (MO). This work provides not only an efficient alternative to traditional hydrometallurgical methods but also new insights into reaction kinetics and closed-loop material flows for sustainable battery recycling.

Impurity reduction remains a critical challenge in aluminium recycling, particularly due to tramp elements such as Sn, Pb, Fe, Ni, and excess Si and Mg in Al–Si alloys used in automotive applications. This study presents a novel, sustainable refining flux synthesized from eggshell-derived calcium oxide (CaO), combined with NaCl, MgCl2, Na2B4O7, and Na3AlF6. The flux was comprehensively characterized using XRD, FTIR, SEM-EDS, and DSC-TGA, and applied to secondary Al–Si melts at 680 ± 20°C. Post-treatment analyses (ICP-MS and OES) demonstrated significant impurity reductions: Fe (22.5%), Si (19.5%), Mg (31.7%), and Zn, Pb, and Sn reduced by over 80%. The overall aluminium purity increased from 84.2 to 87.6 wt %. Dross analysis confirmed successful impurity segregation via slag formation, chlorination, and oxide capture. The results highlight the flux’s effectiveness in enhancing melt cleanliness while valorising bio-waste, providing a scalable, eco-friendly alternative to conventional fluxes in secondary aluminium recycling.

The rapid advancement in electronic and communication technologies has improved connectivity but increased electromagnetic wave pollution, posing health risks and disrupting systems. Lightweight, thin microwave-absorbing materials with broad frequency absorption are essential for mitigating electromagnetic interference. This review highlights advanced composites, magnetic alloys, and carbon-based materials like carbonized melamine foam (CMF), a porous structure promising for dielectric absorption, though limited by high conductivity. Combining CMF with insulating layers and magnetic coatings such as FeNi and SiO2 enhances absorption by optimizing impedance matching. Magnetic alloys and dielectric coatings applied via magnetron sputtering improve absorption by balancing permeability and permittivity, critical for high efficiency in the X- and Ku-bands. The study explores FeCo-coated carbon nanofibers and SiC fibers, revealing how microstructural properties influence performance. This comprehensive analysis aids the design of stable, efficient electromagnetic absorbers for broad-spectrum applications.

The Chaabet El Hamra deposit in northeastern Algeria represents a promising but mineralogically complex zinc resource. This study investigates the optimization of flotation parameters to enhance zinc recovery and concentrate quality. Detailed mineralogical and granulometric analyses revealed that sphalerite was the primary zinc-bearing mineral, finely disseminated within a gangue matrix dominated by quartz and dolomite. Experimental grinding tests indicated that milling for 42–45 min achieved optimal liberation at 74 µm, a critical threshold for effective flotation. Flotation trials were performed under varying conditions of copper sulfate activation, amyl xanthate dosage, and froth scraping times. The highest zinc recovery (86.31%) and concentrate grade (49.05%) were obtained at a collector dosage of 150 g/t, an activator dosage of 200 g/t, and a 7-min scraping duration. Kinetic modeling using both first-order and Kelsall’s two-component models confirmed the flotation system’s efficiency and highlighted the coexistence of fast- and slow-floating mineral fractions. Response surface methodology (RSM) further elucidated the nonlinear interaction between reagents, defining an optimal operating window. The study provides a comprehensive framework for industrial flotation optimization and demonstrates the value of integrating kinetic modeling with mineralogical characterization. These findings contribute to improving the economic and environmental performance of zinc beneficiation in polymetallic ore contexts. The optimum flotation conditions (pH 9, 500 g/t collector dosage, and 10 min conditioning time) provide a robust basis for upscaling the process to industrial scale.

The true stress-true strain curves of a biomedical grade Co–28Cr–6Mo alloy were obtained through isothermal uniaxial compression tests on a Gleeble-3800 thermo-mechanical simulator. Based on the experimental data, the modified Johnson–Cook model, strain compensated Arrhenius-type model and microstructure-based constitutive model were constructed in a wide range of temperatures (900–1200°C) and strain rates (0.001–10 s–1). The prediction accuracy of the developed constitutive models was estimated by the determination coefficient and the average absolute relative error between experimental and predicted flow stress values. These values are 0.9857 and 7.8% for the modified Johnson-Cook model, 0.9504 and 13.01% for the strain compensated Arrhenius-type model, and 0.9948 and 2.45% for the microstructure-based constitutive model, respectively. The result clearly demonstrates that the microstructure-based constitutive model is able to describe the hot flow stress behavior more correctly, compared to the other proposed constitutive models.

In this study, an Al7075 matrix composite reinforced with nano-sized fly ash (FA) and cenosphere (CS), a waste product from thermal power plants, was fabricated using an ultrasonic cavitation-assisted stir casting method. These nanoparticles were added at amounts of 0.6, 1.2, and 1.8 weight percent. Microstructural inspection using scanning electron microscopy (SEM) was conducted to verify the dispersion of particles in the composite. The tensile strength, compressive strength, and hardness of the composite were determined through mechanical characterization. Results depict that, for the Al7075/FA1.8 composite, the ultimate tensile strength, ultimate compressive strength, and hardness values have improved by 47, 26, and 30%, respectively, compared to the AL7075 alloy. For Al7075/CS1.8, the composite ultimate tensile strength, ultimate compressive strength, and hardness value have been improved by 59, 34, and 37%, respectively, compared to the Al7075 alloy. A sliding wear test assesses the wear characteristics of the composite. In comparison to the Al7075 alloy, a maximum improvement of 63% in wear rate has been reported for the Al7075/FA1.8 composite. Moreover, a maximum improvement of 72% has been observed for the Al7075/CS1.8 composites compared to the Al7075 alloy.

Selective laser melting (SLM) technique is one of the most popular advanced manufacturing techniques. The SLM process parameters affect the multiple quality-attributes of the SLM-built parts. The aim of this work is to develop a new optimization methodology of the SLM process parameters for improving the multiple quality attributes of the SLM-built parts. It is a multi-objective optimization (MOO) problem. The multiple quality attributes are converted into a single overall quality index (OQI) using multi atrribute decision making (MCDM) method, and the MOO problem converted into a single objective optimization (SOO) one. The optimization result may differ according to the applied MCDM method. To address it, this work proposed a reasonable process optimization methodology for improving multiple quality attributes of the SLM-built parts using integrated OQI (I-OQI) combined with multiple OQIs obtained from multiple MADM methods. The proposed methodology was applied to optimize the process parameters such as laser power (LP), scan speed (SS) and overlap rate (OR) for improving five quality attributes such as tensile strength, hardness, relative density, volumetric energy density, and build rate of the SLM-built AlSi10Mg alloy. The optimal values of the SLM process parameters obtained from Taguchi and grid search optimization methods were LP of 320 W, SS of 900 mm/s, and OR of 0.25. The methodology could be actively applied to the SLM process optimization for not only Al alloys but also various metal/alloys.

In this study, a comprehensive method for processing lithium-ion battery electrode material is proposed, based on the selective cuprum leaching using an NH4HCO3 liquor followed by its sorption using the ion-exchange resin Purolite S930 Plus. Certain optimal conditions for ammoniacal leaching ensure cuprum recovery at approximately 90%. Loading tests demonstrated a high static sorption capacity of the resin—125.4 mg g–1, while dynamic experiments and elution using H2SO4 showed the possibility of efficient cuprum recovery and resin regeneration. Additional analyses using IR and XPS spectroscopy confirmed the formation of stable coordination bonds between cuprum ions and the functional groups of the resin. The obtained results indicate the promise of the proposed technology for the industrial processing of spent lithium-ion batteries to recover valuable metals.

We employ first-principles calculations to investigate the structural stability and electronic properties of cubic zinc oxide (ZnO) and Zinc sulfide (ZnS) heteroclusters adsorbed with H2O molecule. A comprehensive investigation on H2O grabbing by ZnO/ZnS heteroclusters was carried out using DFT computations at the CAM–B3LYP–D3/6–311+G (d, p) level of theory. The notable fragile signal intensity close to the parallel edge of the nanocluster sample might be owing to H/OH binding induced non-spherical distribution of ZnO or ZnS heterocluster. The hypothesis of the energy adsorption phenomenon was confirmed by density distributions of CDD, TDOS and ESP for ZnO/ZnO–H2O or ZnS/ZnS–H2O. A vaster jointed area engaged by an isosurface map for H/OH adsorption on ZnO or ZnS surface towards formation of ZnO–H2O or ZnS–H2O complex due to labeling atoms of O1, Zn15, O27 or S27, H29, H30. Therefore, it can be considered that zinc in the functionalized ZnO or ZnS might have more impressive sensitivity for accepting the electrons in the process of H/OH adsorption. It is considerable that when all surface atoms of ZnO or ZnS are coated by OH and H groups, the semiconducting behavior is recovered. Our results open up the possibility of tailoring the electronic properties by controlling the surface adsorption sites.

As traditional hypereutectic Al–Si alloy modifiers, P and Sr can effectively improve the comprehensive mechanical properties of alloys when the alloy is double modified, with the interaction between these composite modifiers affecting the modification effect of the alloy. Therefore, in this study, the transformation of the AlP to Sr3P2 phase during P and Sr composite metamorphism was predicted using first-principles calculations based on density functional theory. In addition, Al–15%Si alloys with P and Sr single and composite metamorphism were prepared by gravity casting, and the metamorphism effects were evaluated by microstructure observations and mechanical property testing. The results showed that the Sr3P2 phase was more stable than the AlP phase. The experimental results demonstrated that the Sr3P2 phase was present in the composite alloy after modification and that the modification effect of primary silicon and eutectic silicon was not ideal. The composite metamorphism improved the comprehensive mechanical properties of the alloy more obviously than single metamorphism, but it did not reach the superposition of single metamorphism mechanical properties, in which the alloy after the addition of Sr and P had the best properties, and the tensile strength, elongation, and hardness reached 301.5 MPa, 0.87%, and 127.8 HV, respectively. Therefore, this method offers an effective strategy for optimizing the modification treatment of hypereutectic Al–Si alloys.