Role of simple anionic ligands in deep decontamination of liquid radioactive waste

Resumo

The influence of the NO₉^-, SO₄^2–, HCO₃^–, and Ac^– anions on the efficiency of the sorption of bivalent metals by sulfonic cation exchangers was studied. The main method was elution of the Mg²⁺, Ca²⁺, and Co²⁺ cations with individual solutions of the corresponding sodium salts and their mixed solutions with sodium nitrate from the Dowex-50 ion-exchange resin at fixed temperatures. The exchange efficiency is influenced both by neutral complexes of the metal cations mainly with inorganic acid ligands and by the single-charged species. The latter species affect the efficiency of the ion-exchange waste reprocessing considerably more strongly. An increase in the temperature of the solution being treated leads to a significant shift of the peak position toward larger retention volumes, which indicates that it is appropriate to perform the water treatment on sulfonic cation exchangers at elevated temperatures. The first formation constant of the single-charged cobalt dihydrogen phosphate complex species at an ionic strength of 0 M was obtained: logK₁(CoH₂PO₄⁺) = 1.36.