Electrochemical Study of OH− in Molten MgCl2-NaCl-KCl Salts

Abstract

The present study determines the equilibrium concentration of OH- in molten MgCl2-NaCl-KCl salts and measures the kinetic properties data of OH- (diffusion coefficient, exchange current density, charge transfer coefficient, limiting current density, and standard rate constant) accordingly at different temperatures. The equilibrium concentration of OH- descends as the temperature increases, which ranges from 4.11 to 2.84 × 10−6 mol cm−3 in the temperature range of 600 °C–800 °C. The diffusion coefficient follows Arrhenius law with a value between 2.46 and 4.48 × 10−4 cm2 s−1. The exchange and limit current densities, and standard rate constant increase with temperature. The calculated standard rate constant k0 follows Arrhenius law, which is in the range from 1.23 to 2.50 × 10−4 cm s−1. The measured charge transfer coefficient is independent of temperature, which validates the present measurements.