Understanding the behaviour of cloud point extraction of uranium in terms of the zeta potential of colloidal dispersion

The behaviour of various ligands like trioctylphosphine oxide (TOPO), tributylphosphate (TBP), N,N,N',N'-trioctyl diglycolamide (TODGA) and dihexyloctanamide (DHOA) towards the cloud pont extraction (CPE) of the uranyl ion in nitrate medium is explained in terms of the zeta potential (ζ) of the colloidal dispersion. The higher extraction efficiences of U in CPE using TODGA and DHOA over TBP and TOPO as compared to their trend in conventional solvent extraction were attributed due to the higher zeta potential of their respective colloidal dispersion. In addition to that the ζ was found to have a direct correlation with the extraction efficiency of the metal ion by a particular ligand at various pH. (author)