Molten salts have been proposed to be promising candidates as primary and secondary coolants or liquid fuel solvents in MSRs, and heat transfer fluid and thermal energy storage salt for the CSP plants. Structural materials corrosion has been one of the major issues that limited the applications of molten salts. Impurities, such as OH- and H2O can accelerate material corrosion. The fundamental kinetic parameters of these impurities are of importance to understand the corrosion mechanism in the molten salts. In the present work, the electrochemical measurements were conducted in molten MgCl2-KCl-NaCl salts with different concentration of NaOH (0.04-4wt%) at different temperatures (600-800°C). Due to the high temperature and co-existence of OH- and Mg2+, the reaction of Mg (OH)2(l) = MgO(s) + H2O was thermal-favored. Thus, the real concentration of OH- was determined from equilibrium concentration difference of Mg2+ before and after OH- addition with the assistance of ICP-MS analysis. Moreover, the fundamental data of OH- (diffusion coefficient and exchange current density ) were measured accordingly using cyclic voltammetry and potentiodynamic scan, which followed Arrhenius law and were in the reasonable range comparing with values of Fe, Ni or Cr ions in our previous study.

Electrochemical study of OH- in molten MgCl2-NaCl-KCl salts

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.