Sorption of 90Sr and 90Y with the Vaterite Modification of Calcium Carbonate

Highly dispersed vaterite, a metastable modification of CaCO₃, can efficiently sorb ⁹⁰Sr²⁺ and ⁹⁰Y³⁺ ions from neutral aqueous solutions. The sorption proceeds in two stages. The first, rapid, stage (15-20 min) consists in adsorption of the radionuclide ions at active surface sites. The second, slow, stage (3-4 days) consists in irreversible capture of the radionuclides in the bulk upon transition of vaterite to calcite by the recrystallization mechanism.