Electrochemical mechanism of tin membrane electro‐deposition in chloride solutions

Abstract

AbstractBACKGROUNDA new membrane electro‐deposition based process for tin recovery from stannous solid waste was introduced. Linear sweep voltammetry (LSV), cyclic voltammetry (CV) and chronoamperometry (CHR) was applied to investigate the electrodeposition of tin(II) from a stannous chloride acid electrolyte containing an amine non‐ionic surfactant by using a membrane cell.RESULTSElectrochemical mechanism analysis results showed that 0.3% vol. amine non‐ionic surfactant facilitated ions diffusion by increasing the diffusion coefficient from 8.32E‐12 m2 s−1 to 2.85E‐11 m2 s−1, and inhibited tin(II) ions reduction as well as tin nucleation and hydrogen evolution. The applied ionic membrane did not hinder tin electrodeposition, while tin(II) ions reduction and hydrogen evolution was weakened with increasing HCl concentration from 1.5 to 4.5 mol L−1 and Sn2+ concentration increased from 20 to 80 g L−1.CONCLUSIONSThe tin(II) reduction process is proved to be irreversible and diffusion‐controlled, while the nucleation and growth of tin was involved in the process of diffusion for the proton reduction occuring in parallel with tin electrodeposition, and the process follows the mechanism of three‐dimensional instantaneous nucleation and subsequent grain growth limited by diffusion. © 2016 Society of Chemical Industry