Separation of U(IV) and U(VI) by ion exchange chromatography on lanthanum ammonium oxalate

A new inorganic exchanger consisting of lanthanum ammonium oxalate (LAOX) has been prepared and studied, and application to the separation of U(IV) and U(VI) has been explored after measuring, by the batch exchange method, the distribution coefficients. A hydrochloric acid-acetic acid mixture represents the most appropriate medium, among those tested, for performing the separation. Sorption is negligible for U(VI) but is relevant for U(IV) and it can be ascribed to the formation of an insoluble lanthanum uranium and ammonium oxalate. Desorption is possible only by using as eluent a hot solution of EDTA.