State of uranyl arsenates MIAsUO6•nH2O (MI-H+, Li+, Na+, K+, Rb+, Cs+, NH4+) in aqueous solution

The state of uranyl arsenates with general formula (MAsUO6)-As-I center dot nH(2)O, M-I = H+, Li+, Na+, K+, Rb+, Cs+, NH4+ have been investigated in aqueous solutions. The pH ranges of existence of these compounds in aqueous solutions, transformation products and solubility of (MAsUO6)-As-I center dot nH(2)O have been established. Solubility products, standard Gibbs free energies of the uranyl arsenates formation, speciation diagrams for uranium (VI) and arsenic (V) in saturated aqueous solutions and equilibrium solids have been calculated on the basis of the experimental data.