Synthesis of Cu and CuO nanoparticles from e-waste and evaluation of their antibacterial and photocatalytic properties.

Waste printed circuit boards (WPCBs) contain a plethora of valuable metals, considered an attractive secondary resource. In the current research, a hydrometallurgical process combined ammonia/ammonium chloride leaching and reduction (using L-ascorbic acid) to recover copper and its oxide (CuO) as nanosized particles from WPCBs was investigated. The results of leaching indicated that 96.7% of copper could be recovered at a temperature of 35 °C for a leaching duration of 2 h with ammonium chloride and ammonia concentration of 2 mol/L at a solid:liquid ratio of 1:10 g/cm3. The synthesized particles exhibit spherical and distorted sphere morphology with average particle size of 460 nm and 50 nm for Cu and CuO NPs, respectively. The antibacterial activity of Cu, CuO, and a (1:1) blend of both (Cu/CuO) has been examined against five different bacterial and fungal strains. The highest zone of inhibition was measured as 21.2 mm for Cu NPs toward Escherichia coli and 16.7 mm for Cu/CuO blend toward Bacillus cereus bacteria. The highest zone of inhibition was measured as 13 mm and 13.8 mm for Cu/CuO blend toward Fusarium proliferatum and Penicillium verrucosum fungi. Cu/CuO blend showed notable photocatalytic activity towards Rhodamine B dye under visible light irradiation with 96% degradation rate within 120 min. Using the process developed in this study, copper and its oxide as nanoparticles can be produced from WPCBs and used for multifunctional applications.

Zinc ferrite nanoparticles from industrial waste for Se (IV) elimination from wastewater.

The presence of high concentrations of selenium ions in wastewater is considered an environmental problem. However, the mechanism of selenium ions (Se (IV)) removal by the adsorption process has not been investigated in-depth so far. Also, the recovery and conversion of the industrial waste materials into valuable materials is a vital issue. Therefore, in this study, zinc ferrite nanopowders are economically synthesized from steel-making wastes by co-precipitation method for investigating as adsorbents of selenium species. The produced nanopowders were annealed at 150, 300, 500, and 850 °C for 5 h to scrutinize the impact of annealing temperature on their crystallite size. The compositional, optical, and magnetic features of the nanopowders were defined by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), UV-Vis. spectrophotometer along with vibrating sample magnetometer (VSM). Optical absorbance spectra were found characteristic due to the electronic structure of Fe3+ (3d5) considering the C3v local symmetry of Fe3+ ions. The prepared nanopowders demonstrated good adsorption capacity toward selenium ions (43.67 mg/g at pH 2.5) from an aqueous medium. Adsorption data were found fitting to Freundlich isotherm model. Thus, ZnFe2O4 can be recommended to effectively eliminate selenium ions from aqueous solutions.