Abstract
The extractive properties of tri-isoamyl-phosphate (TAP), an indigenously prepared extractant, and the loading capacity of extraction solvent containing TAP for U(VI) and Pu(IV) ions in nitric acid solution have been investigated. The dependence of the distribution ratio on the concentration of nitric acid showed that TAP has an ability to extract these actinides, while the fission product contaminants are poorly extracted. The distribution data revealed a quantitative extraction of both U(VI) and Pu(IV) from moderate nitric acidities in the range 2-7 mol.dm(-3). Slope analysis proved predominant formation of the disolvated organic phase complex of the type UO2(NO3)(2).2TAP and Pu(NO3)(d).2TAP with U(VI) and Pu(IV), respectively. On the contrary, the extraction of fission product contaminants such as Ce-144, Cs-137, Nb-95, Pr-147, Ru-106, Zr-95 was almost negligible even at very high nitric acid concentrations in the aqueous phase indicating its potential application in actinide partitioning. The recovery of TAP from the loaded actinides could be easily accomplished by using a dilute sodium carbonate solution or acidified distilled water (approximate to 0.01 mol.dm(-3) HNO3) as the strippant for U(VI) and using uranous nitrate or ferrous sulphamate as that for Pu(IV). Radiation stability of TAP was adequate for most of the process applications.