Extraction of U(VI) and Th(IV) from nitric acid medium using tri(butoxyethyl) phosphate (TBEP) in n-paraffin

Extraction behavior of U(VI) and Th(IV) from nitric acid medium is investigated using organo-phosphorous extractant, tri(butoxyethyl) phosphate in n-paraffin at room temperature (27 ± 1 deg C). The effect of diluents, nitric acid concentration as well as extractant concentration on extraction of U(VI) and Th(IV) are evaluated. Extraction of U(VI) and Th(IV) from nitric acid medium proceeds via solvation mechanism. Slope analysis technique showed the formation of neutral complexes of the type of UO2(NO3)2 · 2TBEP and Th(NO3)4 · 3TBEP with U(VI) and Th(IV) respectively in the organic phase. The FTIR data showed shifting of P=O stretching frequency from 1,282 to 1,217 cm-1 indicating the strong complexation of P=O group with UO22+ ions in the organic phase. Effect of stripping agents, other metal ions and their separation with respect to U(VI) extraction has also been investigated. (author)