UPHILL AND SELECTIVE TRANSPORT OF ALKALI AND ALKALI EARTH METAL-IONS THROUGH 2,3-EPITHIOPROPYL METHACRYLATE-2-ACRYLAMIDE-2-METHYL PROPANE SULFONIC-ACID COPOLYMER MEMBRANES

Cationic exchange membranes were prepared with 2,3‐epithiopropyl methacrylate (ETMA)‐2‐acrylamide‐2‐methyl propane sulfonic acid (AMPS) copolymers. Transport of alkali and alkali earth metal ions against their concentration gradient through the membranes was investigated by using the system, where one side (L side) of the membrane in a diaphragm cell was acidic and the other (R side) alkaline or neutral, under various conditions. The ETMA‐AMPS copolymer membranes transported rapidly alkali and alkali earth metal ions against their concentration gradient even from their neutral salt solution. The transport rate and transport fraction of metal ions were greatly affected by the composition of the copolymer membranes and H+ concentration in the L side. The transport selectivity between alkali metal ions was affected by the composition of the copolymers and the selectivity between alkali and alkali earth metal ions was affected by initial H+ concentration in the L side. Copyright © 1990 John Wiley & Sons, Inc.