(searched for: "10.5155/eurjchem.7.1.42-48.1348")
European Journal of Chemistry, Volume 7, pp 42-48; doi:10.5155/eurjchem.7.1.42-48.1348
Abstract: For the first time, the continuous variation method was applied for the evaluation of the stoichiometry of uranyl phosphate complexes sorbed on bentonite. Sorption of UO2(CH3COO)2⋅2H2O in the presence of Na2HPO4⋅7H2O from 0.001 mol/L solutions led to the appearance of maxima in the sorption peaks of U(VI) and P(V) ions at molar ratios of [U(VI)]/[P(V)]s = 1.4, 3.3, 3.6 and 1.2, 1.7. It is suggested, based on complementary XRD and XPS data, that the UO2HPO4 complex is located on aluminols (ºAl-OH) whereas the (UO2)3(PO4)2⋅4H2O complex is precipitated in the interlamellar space of bentonite. The participation of (UO2)3(OH)5+ and (UO2)4(OH)7+ species in the formation of U(VI) surface complexes is suggested, based on the deconvolution of sorption spectra of U(VI) on the bentonite in the presence of phosphates.