Highly efficient separation of lithium chloride from seawater.

A complexing reagent composed of two bipyridine moieties enabled the efficient separation of lithium chloride through liquid membrane from seawater, in which 0.005% lithium chloride is contained (more than 99% metal chlorides are NaCl, KCl, MgCl2, and CaCl2). That is, two separations by our liquid membrane changed the molar ratio of LiCl from 0.005% to 80%. The striking characteristic of this compound is that the lithium ion is separated efficiently from alkali and alkaline earth metal ions without the lipophilic anion. Thus this new membrane system contructed by us offers a low-energy, low-cost, and environmentally friendly method to enable the routine use of lithium chloride separation from seawater.