EFFECT OF SYNTHESIZED SURFACTANTS IN THE SEPARATION OF RARE-EARTH-METALS BY LIQUID SURFACTANT MEMBRANES

Synthesized surfactants have been applied to the separation and concentration of rare earth metals by liquid surfactant membranes (LSMs). Using newly synthesized surfactants, extraction of lanthanum (La), praseodymium (Pr), and neodymium (Nd) by LSMs was carried out with (2-ethylhexyl)phosphonic and mono(2-ethylhexyl) ester as a carrier. The effects of the synthesized surfactants on the extraction and separation of these metals were investigated. Rate constants in LSMs were obtained from the analysis with an interfacial reaction model for each rare earth metal. It was found that the surfactant strongly affects the extraction rate and separation of rare earth metals by LSMs. Among them, a cationic surfactant having two oleyl chains showed the best separation factor in the extraction of La, Pr, and Nd by LSMs. Further, the extraction rate of the cationic surfactant was about 40 times higher than that of a commercial surfactant such as Span 80.