Extraction of Am(III) and lanthanides(III) with organo dithiophosphinic acids

Abstract

Extraction of Am(III) and Ln(III) from NaClO₄ medium has been investigated with di(2-ethylhexyl) dithiophosphoric acid, di(2-ethylhexyl) monothiophosphoric acid, di(2-ethylhexyl) monothiophosphinic acid, octylphenyl dithiophosphinic acid and 11 kinds of dialkyl dithiophosphinic acids (alkyl = hexyl, heptyl, octyl, nonyl, 2-ethylhexyl, 1-methylheptyl, phenyl, chlorophenyl, methylphenyl, 2,5-dimethylphenyl, and 3,5-dichloro-4-methylphenyl) in xylene. The effect of chemical structures of those extractants on separation capability has been studied. The relationship between the slope value of the lgD−pH and extraction conditions can be described as: lgS=alg(C_HA/C_M^S/4)+b. In the presence of macro amounts of Eu(ClO₄)₃, the formula, lg SF_Am/Eu=B−2lg(C_HL−D_Eu/(D_Eu+1)C_Eu), can well describe the relationship between separation factor and the extraction condition. A high separation factor (SF_Am/Eu=2500) is obtained by solvent extraction from 1 mol/L NaNO₃ solution with 0.5 mol/L di(2-ethylhexyl) dithiophosphinic acid in toluene.