Extracted Species of Rare Earth Elements Using Bis(1,1,3,3-tetramethylbutyl)phosphinic Acid as an Extractant and Their Effective Mutual Separation by High-Performance Extraction Chromatography

Abstract

Abstract The possible extracted species of rare earth elements (REE) in bis(1,1,3,3-tetramethylbutyl)phosphinic acid (Hmbp)/cyclohexane–HNO3 system was proposed by a log–log plot analysis and a saturated extraction method as being [M(mbp)3(Hmbp)3] (M = REE). It was also verified by IR, 1H NMR spectra and element analysis of lutetium–Hmbp extracted species. The effective mutual separation of REEs was achieved on the Hmbp modified C-18 column by a pH gradient elution. Moreover, the degree of the mutual separation of europium(III) from gadolinium(III) was remarkably improved by adding glycollic acid in the mobile phase. A fine concentrate of Sm2O3, Eu2O3, and Gd2O3 from a rare earths smeltery was analyzed by the present method with the spectrophotometric detection after postcolumn derivatization with Arsenazo III.