THE EFFECT OF TIN CONCENTRATION ON THE ELECTRODE PROCESSES OF TIN ELECTRO-REFINING IN HCl SOLUTIONS

This study investigates the effect of tin concentration on the electrode processes of tin electro-refining in hydrochloric acid (HCl) solutions at a concentration of 1 mol/dm³, utilizing different electrolysis cells. A rotating cathode with a centrally positioned vertical axis was utilized to highlight the significance of the cathode's crystal structure. For the potentiostatic and galvanostatic experiments, a specialized computer-controlled potentiostat and current supply were developed. Analysis included plotting cathodic and anodic current densities against overpotential, and measuring cathode potential over time at varying current densities and tin concentrations. Findings reveal that at low tin concentrations, diffusion limiting current appears early, eventually leading to a shift towards hydrogen evolution as the dominant cathodic process, while higher tin concentrations allow for undisturbed tin deposition. Anodic processes remained largely unaffected by the varying conditions. Notably, the optimum energy requirement was identified between 30-90 g/dm³ Sn in the 1M HCl solution at an anodic current density of approximately 300 A/m².