Purification of Lithium Carbonate from Radioactive Contaminants Using a MnO2-Based Inorganic Sorbent

The possibility of deep radiochemical purification of Li2CO3 has been examined in the context of the purification program of the AMoRE collaboration. In this experiment, commercial Li2CO3 was converted into LiNO3. Co-precipitation with inorganic salt-based carriers followed by membrane filtration and sorption using MDM inorganic sorbent methods were tested for the removal of alkaline-earth and transition metals, potassium, magnesium, aluminum, uranium, thorium, and radium. The calcium molybdate-based carrier was the most efficient for removing Th, U, and K. Subsequently, the radium, calcium, and barium contamination was removed with MDM sorbent. After the impurities' removal, the final Li2CO3 product was synthesized with NH4HCO3 sludge. The separation factors were derived by means of ICP-MS and HPGe analyses of the initial material and the intermediate and final products. The study showed the optimum conditions of co-precipitation and sorption to reach a high yield and radiopurity of lithium carbonate used for low-radioactive-background experiments. The developed method is an important step toward performing next-generation large-scale (1-ton) neutrino experiments using Li-containing detectors.