Break-through investigations of uranium isotope separation in the system uranyl ion solution Ti(III)-cationic resin

Break-through studies on separation of uranium isotopes were carried out using a cation exchange resin in Ti(III) form. By analyzing the experimental results the apparent equilibrium constants of the order K=1.00021-1.00034 were obtained. The maximum value of the experimental curves of the isotopic ratio versus effluent volume was interpreted by considering two antagonistic isotope effects: one relatively large given by an exchange reaction between U(IV) on the resin and U(VI) in solution and a smaller one given by the reduction of U(VI) with Ti(III). The difference of the equilibrium constants of these two isotope effects, as a function of temperature, was used for the determination of the apparent thermodynamic values of the resultant process. The experimental determination resulted in ΔH0=0.8542 cal mol-1 and ΔS0=3.33x10-3 cal 0K-1. (author)