Investigation of thorium(IV) separation from cerium(IV) on a silica gel column coated with tri-octylphosphine oxide

The parameters effecting the efficiency of thorium extraction on silica gel coated with tri-octylphosphine oxide(TOPO) such as; HNO3 concentration, thorium concentration, TOPO concentration, flow rate and nature of diluent were studied and optimum conditions were determined. Various elution reagents were tried to elute thorium from the column. High recovery was obtained with 0.5 M H2SO4, 0.5 M HCl solutions. Extraction data have been used to separation thorium from iron(III) and Ce(IV). The solution that contains Fe(III), Ce(IV) and Th(IV) in nitric media was passed through the TOPO/silica gel column, whilst Th(IV) and Ce(IV) were extracted by TOPO, Fe(III) was not. Firstly Th(IV) was eluted with H2SO4 then Ce(IV) was eluted with HCl. As a result, optimum conditions are here reported for the separation of thorium from cerium(IV). (orig.)