ELECTROCHEMICAL RECOVERY OF LITHIUM IONS IN THE AQUEOUS PHASE

The electrochemical insertion of lithium ions into a Pt/lambda-MnO2 electrode was investigated in various metal chloride solutions. The Li+ insertion occurred effectively in LiCl solutions with higher concentration than 10 mmol/dm3, but it could hardly occur in a 0.1 mmol/dm3 LiCl solution. Alkaline earth metal ions showed a stronger inhibition effect against the Li+ insertion into the Pt/lambda-MnO2 electrode than alkali metal ions. However, since only Li+ ions were taken up from a mixed solution of lithium and alkaline earth metal chlorides, a high selectivity of the electrode for lithium ions was shown. It was possible to recover lithium ions from geothermal water by this electrochemical method using the Pt/lambda-MnO2 electrode; the lithium uptake was 11 mg/g-MnO2.