Estimation of deuterium recoveries from each component of water-isotope mixture in continuous-flow thermal diffusion columns

The present study deals with the estimation of deuterium recovery from the separation of water–isotope mixture (H₂O–HDO–D₂O) by continuous-flow thermal diffusion. First, the equations for predicting the degrees of separation for each component in H₂O–HDO–D₂O system were derived. The recovery of deuterium (D) was then estimated from the degrees of separation of HDO and D₂O. The most important assumption in this work was that the concentrations of each component were at local equilibrium within the thermal diffusion column, i.e. H₂O + D₂O ⇄ 2HDO. It was found that D₂O preferably transfers to the bottom end of the column, while HDO does the same for dilute feed concentration, but then transfers to the top of the column when the feed concentration of D₂O, C_3F, increases to 0.3. The maximum total recovery of deuterium from HDO and D₂O occurs at C_3F = 0.25.