Separation and Concentration of Rare Earth Ions by Liquid Membranes

Abstract

Effects of carrier type and membrane solvent on carrier-mediated transport of trivalent rare earth ions through liquid membranes are described. The liquid membranes are the supported type and the solvent polymeric membrane which consists of cellulose triacetate containing a plasticizer. In counter-transport of rare earth and hydrogen ions using β-diketones as carriers, the difference in flux among rare earths is slight, with the exception of Sc. In the transport using hinokitiol, the fluxes for the lanthanides from Sm to Lu are much higher than those from La to Nd. The flux using flavonol increases with an increase in atomic number. In these transport processes, the flux is affected by the composition of membrane solvent and by the pH and added anion in the source phase. In co-transport of rare earth and thiocyanate ions using phosphoric acid triesters as carriers, only scandium is transported.