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. [Display omitted] •Steel-making wastes are used to prepare Zn ferrite NPs at room temperature.•Co-precipitation technique for preparing Zn ferrite NPs is used.•Adsorption of heavy metals (Se (IV)) from wastewater by ZnFe2O4 NPs is explored.•Adsorption data excellently fitted Freundlich isotherm with a high uptake capacity.•A mechanism of Se (IV) removal by the adsorption process is proposed.