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

Synthesized surfactants have been applied to the separation and concen tration of rare earth metals by liquid surfactant membranes (LSMs). Us ing newly synthesized surfactants, extraction of lanthanum (La), prase odymium (Pr), and neodymium (Nd) by LSMs was carried out with (2-ethyl hexyl)phosphonic and mono(2-ethylhexyl) ester as a carrier. The effect s of the synthesized surfactants on the extraction and separation of t hese metals were investigated. Rate constants in LSMs were obtained fr om the analysis with an interfacial reaction model for each rare earth metal. It was found that the surfactant strongly affects the extracti on rate and separation of rare earth metals by LSMs. Among them, a cat ionic surfactant having two oleyl chains showed the best separation fa ctor in the extraction of La, Pr, and Nd by LSMs. Further, the extract ion rate of the cationic surfactant was about 40 times higher than tha t of a commercial surfactant such as Span 80.