Lithium separation by growth of lithium aluminum layered double hydroxides on aluminum metal substrates

We propose a reaction scheme to selectively separate lithium ions from an aqueous urea solution by formation of lithium aluminum layered double hydroxide (LDH) on aluminum metal foils. The repeated cycles of adsorption and desorption of lithium ions are possible using the topotactic reaction of lithium salts with Al(OH)3 grown on an aluminum metal surface in aqueous solution. The urea and lithium salt concentration, pH, and reaction time are critical parameters for modulating the maximum yield of recovered lithium quantity, which is 8 μg/cm2 of aluminum metal surface. The adsorbed lithium is strongly correlated with saturation conditions of lithium and urea, dependent upon competition between the rate of crystal growth and that of nucleation of LDH. The kinetic study of sorption and surface characterization provides a possible mechanism for the lithium exchange reaction and suggests the facile methodology of a lithium recovery system.