The Efficient Separation of Lithium Chloride by Acyclic Carrier Molecules

A new acyclic carrier molecule (1) (2,9-didodecanoylamino-1,10-phenanthroline) for the separating purpose of lithium chloride was synthesized by a simple, short synthetic route. Carrier (1) exhibited the high selectivity for binding to the Li + ion, and has enough ability to form a stable complex consisting of one carrier (1) and one Li + ion. LiCl is separated efficiently from the mixture of various alkali metal chlorides by using liquid membranes containing carrier (1). The transport rate and selectivity by carrier (1) can are changed by the concentration of metal salts and the properties of anion in the source phase. Two different transport mechanisms are proposed for the explanation of this transport result and molecular orbital calculations on two proposed carrier (1)-Li + complexes provide a possibility of supporting above explanation. The numerical simulation of Li + transport using the rate equation of a simple model suggests that the transport by carrier (1) is promoted due to the diffusion limited process and this property is similar to other previously reported macrocyclic carrier molecules. These results indicate an important fact that simple, acyclic compounds have enough ability as LiCl carrier, though the complicated macrocycles with small cavity have been known as Li + ion selective carriers.