Deuterium enrichment by proton exchange membrane water electrolysis with electrolyte circulation

Hydrogen isotopes will be new energy sources in nuclear fusion. In this study, a batch system for producing heavy water was developed in which pure water with deuterium (D) was circulated during proton exchange membrane water electrolysis. Deuterium was enriched by up to 94.7 at.% from 51.1 at.%. The D components of water and gas were analyzed during electrolysis. The relationship between the concentration of D (CD) and the electrolytic consumption ratio (R) was evaluated. This relationship was simulated using a mass balance model. From the gas analysis, the separation factor alpha was calculated. It was found that alpha depended on the ratio among H2O, HDO, and D2O to maintain the equilibrium state of the chemical exchange reaction.