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

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 k 0 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.