Separation of Isotopes of Lithium and Uranium by Electromigration Using Cation-Exchange Membranes

Isotope separation by chromatographic electromigration has been studied for lithium (6Li and 7Li) and uranium (235U and 238U), using cation-exchange membranes as migration media. The membranes were pulled back against the direction of the movement of isotopic cations in a countercurrent manner. In both cases of the elements the lighter isotope, 6Li or 235U, was concentrated at the frontal part of a migration zone; at the extreme front the 6Li atom % increased to 16.8% from the original value of 7.5% after 386 cm migration, and the 235 U atom % rose to 0.743% from the original value of 0.723% after 200 cm migration. Isotope separation coefficients were experimentally determined: ε = (3.7 ± 0.4) μ 10−3 for lithium isotopes, and two slightly different values ε = (4.9 ± 1.0) μ 10−5 and (5.4 ± 1.1) μ 10−5 for uranium isotopes. The steep isotope accumulation was observed in a narrow boundary region. A mathematical expression for the isotope accumulation curve was derived, and the slope of the curve was assessed for each experimental result.