A comparative evaluation of synergistic extraction behaviour of hexavalent uranium with thenoyl tri-fluoro-acetone (HTTA) and 1-phenyl, 3-methyl, 4-benzoyl pyrazolone-5 (HPMBP) using mono-functional and bi-functional neutral donors

Abstract

SummarySynergistic extraction of hexavalent uranium was studied using acidic extractants HTTA/HPMBP with two different bifunctional neutral donors, DHDECMP and CMPO, from HNO3medium at various fixed temperatures. The equilibrium constants for the organic phase addition reaction (logKs) were correlated with the basicity (Kh) of the neutral donors. The data reported earlier for monofuctional neutral donors (DPSO, TBP, TOPO) were used for the comparison. A linear correlation between logKsand logKhwas observed for U(VI)/HTTA/S (S = neutral donor) system. However, in U(VI)/HPMBP/S system, the observed logKsvalues for bifunctional neutral donors were much lower than those expected from linear correlation. This was attributed to the different mechanisms operative in the synergistic extractioni.e. substitution in the formervs. addition in the latter. These conclusions are also supported by the thermodynamic data obtained in the present studies. Nevertheless, it is seen that bifunctional neutral donors act only as monofunctional with both HTTA and HPMBP.