The physicochemical forms of traces of radium in aqueous solutions containing chlorides, sulfates and carbonates

The physicochemical state of radium in aqueous solutions was studied using centrifugation with free-liquid electrophoresis and 224Ra (8-40 pg.lambda-1). The radium did not form centrifugable particles (d>12 nm) in most of the solutions studied. Electrophoretic mobilities of radium determined in 0.01M chloride solutions suggest that only Ra2+ cations are present between pH 2 and 7. In solutions containing sulfates, carbonates and hydrogencarbonates, the existence of significant amounts of radium complexes has been indicated. The stability constants of the complexes have been determined. The electrophoresis results give evidence that radium complexes with hydrogencarbonate are rather weak (K1 approximately 3.9, β2 approximately 83). (author)