The dissolution of [226Ra]BaSO4 was investigated by the reduction of the precipitate with NaNO2
in acidic solution. Sodium nitrite is readily soluble in water (85 g/100 g of water @ 25 °C) and its
solubility increases with temperature (Lide, 2005). The sulfate ions were reduced in two stages;
firstly the sulfate reduced to sulfite to form RaSO3 and BaSO3, then, sulfite ions were reduced to
sulfide (S2-). At the end of the oxidation-reduction reactions, Ra and Ba were found in solution as
sulphide salts, which easily react with HNO3 or HCl acid to form the corresponding salts of Ra
and Ba.