Extraction and separation of thorium (IV) and uranium (VI) from nitric acid media using bis (2-ethylhexyl) phosphinic acid extractant

Extraction behaviour of Th(IV) and U(VI) has been investigated with bis(2-ethylhexyl) phosphinic acid(PIA-8) in toluene from nitric acid media. The extraction of U(VI) was found to be quantitative with 0.1 - 2.0M HNO3 acid and in the pH range 1.0 - 3.0 while Th(IV) was completely extracted in the acidic range of 0.1 - 1.5 M HNO3 and in the pH range 1.0 - 3.0 with 1.8 x 10-2 M and 2.3 x 10-2 M PIA-8 in toluene, respectively. The probable extracted species have been ascertained by log D - log C plot as UO2 R2.2HR and ThR4.4HR, respectively. Separation of U(VI) and Th(IV) was also carried out from associated metals. (author)