Production of zinc sulfate from waste zinc carbon batteries

In this study, the dissolution kinetics of metallic zinc in waste zinc carbon batteries was investigated in sulfuric acid solutions in the presence of hydrogen peroxide, and the production of zinc sulfate was performed. The effects of the experimental parameters on the dissolution of metallic zinc in sulfuric acid solution containing hydrogen peroxide were determined, and a mathematical model to demonstrate the dissolution kinetics was suggested. The effects of the concentration of sulfuric acid, concentration of hydrogen peroxide, solid/liquid ratio, reaction temperature and stirring speed on the dissolution of zinc were examined. It was observed that the dissolution yield of zinc increased with increasing the concentration of sulfuric acid, concentration of hydrogen peroxide, stirring speed, and reaction temperature, and with decreasing the solid/liquid ratio. While the concentration of sulfuric acid, volume of hydrogen peroxide, solid/liquid ratio, temperature, stirring speed, and reaction time were 0,3 M, 2 mL, 0,2/500 g/mL, 35°C, 450 rpm, and 60 min respectively, it was determined that 90,14% of zinc was dissolved. In consequence of the kinetic analysis performed, it was detected that the dissolution rate fit to the pseudo-first order kinetic. The activation energy for the dissolution process was calculated to be 22,05 kJ/mol, and it was deduced that the dissolution process was controlled by diffusion. After the dissolution experiments, zinc sulfate monohydrate was produced by evaporative crystallization at 70°C using stock solution prepared. The characterization of the obtained product was performed by XRD and SEM-EDX.