Heavy water recycling for producing deuterium compounds.

Deuterium oxide (D 2 O) is a special variety of water that serves as a crucial resource in a range of applications, but it is a costly and unusual resource. We therefore developed a new D 2 O concentration system that combines a polymer electrolyte water electrolyzer and a catalytic combustor for recycling used D 2 O. In this study, 1.6 L of used D 2 O, with a concentration of 93.1%, was electrolyzed for 13.6 h to obtain 0.62 L of D 2 O, with a concentration of 99.3%. In addition, the recombined water obtained by burning electrolytic gas using the catalytic combustor was also electrolyzed for 8.8 h to obtain 0.22 L of D 2 O, with a concentration of 99.0%. The estimated separation factor of this electrolyzer at 25 °C was 3.6, which is very close to the equilibrium constant of the water/hydrogen isotope exchange reaction. Recycled D 2 O was used as a deuterium source for the deuteration reaction of sodium octanoate, and 93.6% deuterated sodium octanoate was obtained. It is concluded that there were no impurities in the recycled D 2 O that interfered with the deuteration reaction. These results can lead to the development of a cost-effective deuteration method for these materials.