Synthetic inorganic ion-exchange materials. XXXIV. Selective separation of lithium from seawater by tin(IV) antimonate cation exchanger

Tin(IV) antimonate (SnSbA) cation exchanger showed an extremely high selectivity for lithium ions compared with other alkali metal ions. The equilibrium distribution coefficients, K_d, were determined at different concentrations of lithium and sodium ions in hydrochloric acid media by batch technique. The K_d values of lithium ions increased with decreasing concentration of lithium ions in the solution, while those of sodium ions were almost independent of sodium concentrations. This behavior can be used to good advantage for the selective separation of lithium at low concentration from sodium ions at high concentration. A successful separation of lithium ions from seawater can be achieved by a column of the SnSbA exchanger in hydrogen ion form. The SnSbA exchanged with lithium and sodium ions can be regenerated using 10 M nitric acid solution as an eluent. Therefore, the SnSbA exchanger can be used repeatedly for the separation of the lithium ions from seawater.