Immobilization of polonium on natural minerals and rocks

Immobilization of 210Ро on natural minerals (magnetite, glauconite), rocks (basalt, dunite), and synthesized manganese dioxide of the composition MnO1.97 was studied. Basic and ultrabasic rocks (basalts, dunites) widely occurring in the nature can be used for making artificial geochemical barriers for the removal of Po from weakly acidic and neutral liquid radioactive wastes. Dunite ensures the most efficient 210Ро immobilization from acidic solutions, and basalt, from neutral solutions. The degree of 210Ро removal upon 48-h interaction with dunite and basalt was 93 and 80% relative to its initial content in solutions with initial pH 3.0 and 7.0, respectively. With all the samples except MnO1.97, the 210Ро immobilization in the initial step (0–5 h) is more efficient in the initially neutral solutions, but with time the degree of the 210Ро removal from the initially acidic solutions becomes higher. The rate of the 210Ро immobilization on MnO1.97 does not appreciably depend on pH in the examined acidity range.