Selective transport of Li-Na and Li-K binary systems across a cation exchange membrane under an electric field

The selective transport for Li-Na and Li-K systems through cation exchange membranes under an electric field was measured as a function of voltage, fe ed concentration, and the number of membranes used in the chamber. The tran sfer rate of metal ions and permeation selectivity were evaluated by conduc ting experiments both in a single and multistage continuous one-pass flow m ode of operation. The results are analyzed on the basis of the concentratio n of alkali metal ions from the feed and recovery side overflows. A compari son of the results obtained from both the single stage and multistage exper iments showed that higher selectivity was obtained for the Li-K system comp ared to the Li-Na system. For the multistage operation, the permeation and selectivity of Li+ and K+ through five and 11 membranes were examined. A hi gh separation factor was obtained when 11 membranes were used. The efficien cy of the recovery of metal ions using membranes may be expressed by the ca lculation of the separation factor and the metal ion concentration obtained from the recovery solution and further enhanced by increasing the number o f membranes used. (C) 2000 Elsevier Science B.V. All rights reserved.