COMPLEXATION AND THERMODYNAMICS OF THE URANYL-ION WITH PHOSPHATE

Complexation of UO2(2+) with the H2PO4- anion at various ionic strengths (0.1-1.0 M NaClO4) has been studied using the solvent extraction technique. The equilibrium constants (beta1 and beta2) for the formation of the species UO2H2PO4+ and UO2(H2PO4)2 were fit to the following extended Debye-Huckel expressions: [GRAPHICS] The thermodynamic parameters for these systems have been computed using the temperature coefficient method. The reactions are favoured by entropy and opposed by enthalpy. The complexes are predominantly the "inner sphere" type.