Multicomponent separations by a combined extraction/electrostatic pseudo-liquid membrane: (I): Separation of Al, La, Sm, and Y

Abstract

The paper reports the results of the development of a combined extraction/electrostatic pseudo-liquid membrane (ESPLIM) concept for the mutual separation of multi–component ( n>2) metal ionic mixtures. Multiple sets of single two-cell ESPLIM equipment were linked up in order to achieve multi-metal separation. The principle of separation is described. A practical demonstration of this concept has been carried out by applying it to a typical mixture of metal ions present in ion-sorbing rare earth ore leachate solution, i.e., Al 3+, La 3+, Sm 3+, and Y 3+: an aqueous solution containing in mg/l Al 200–360, La 250–460, Sm 40–60, and Y 160–340 was used as the feed solution and 20% (v/v) di-(2-ethylhexyl) phosphoric acid (HDEHP) in kerosene was employed as organic membrane phase. The feed solution stream passed through the extraction cell at a flow rate of 1 l/h in once-through mode and the stripping solution passed through the stripping cell at a flow rate of 0.2 l/h in recirculation mode. By controlling the feed pH, organic membrane phase flow rate, and the hydrochloric acid concentration in stripping phase, the separation of Al, La, Sm and Y was obtained.