Selective Adsorption of Lithium Ions from Molten Salt by Activated Alumina

Abstract

Selective adsorption of lithium ions from molten NaNO₃ containing a slight amount of lithium ions was examined using various inorganic adsorbents. Consequently, activated alumina was found to be the most promising adsorbent for adsorption of lithium ions because of its high recovery. Adsorption by activated alumina involved chemisorption with the activation energy of 70.7kJ/mol. It was confirmed that activated alumina showed high stability when mixed with molten salt because no changes of specific pore volume, surface area, or pore size distribution were observed throughout adsorption at high temperatures. Since the adsorption of lithium ions by activated alumina obeyed Freundlich's equation, it was found that the adsorption can be treated as that of lithium ions in dilute solution. The enrichment of lithium ions on activated alumina was much higher than that of sodium ions, indicating that the selective adsorption of lithium ions from molten salt by activated alumina is feasible.