Determination of Optimum Conditions for the Extraction and Separation of Lanthanum, Cerium, Yttrium and Thorium Using Taguchi Method

Abstract

Taguchi method was applied to determine the optimum conditions for the extraction and separation of some lanthanides using three organic extractants. It was found that the optimum results were obtained with trioctylphosphine oxide (TOPO). The extraction efficiency and distribution coefficient of La(III), Ce(III), Y(III) and Th(IV) increased by increasing the salt concentration. Under these conditions 1 M HNO3, 0.1 M TOPO and 10(-1) M KSCN, the extraction efficiency of all metals reached 85%. Based to the Pourbaix diagrams La3+, Ce3+, Y3+ and Th4+ were formed and the stoichiometry of the extracted complexes were [Ln(NO3)(3) center dot 2TOPO](org) and [Th(NO3)(4) center dot TOPO](org).