Extraction Behavior of Pu(Ⅲ) by Di(chlorophenyl)dithiophosphinic Acid

Extraction behavior of Pu(Ⅲ) from HNO₃ solution of low concentration with di (chlorophenyl) dithiophosphinic acid(DCPDTPA) in toluene was studied. The distribution ratios of Pu(Ⅲ) were determined as function of extraction time, pH of the aqueous phase, the concentration of NaNO₃, concentration of DCPDTPA as well as the ambient temperature. The composition of the extraction complex and the extraction reaction equation are discussed, suggesting that the extraction is mainly a cation exchange process, which is exothermic with the extraction enthalpy of (-11.7±0.7)kJ/mol and an equilibrium constant of (0.18±0.03)L/mol at 298 K.