Coupled transport of picrate anion through liquid membranes supported by a microporous polymer film

Abstract

Supported liquid membranes capable of separating and concentrating picrate anions in the presence of noncyclic polyoxyethylene (POE) derivatives are described. The transport of picrate across the membranes was coupled to a flow of alkali metal ions. The membranes consisted of a microporous polypropylene film whose pores were filled with an o-nitrophenyl phenyl ether solution of the POE derivatives. The POE derivatives acted as carriers of the alkali metal ions. The order of their effect on the picrate flux across the membrane was Rb > Cs > K > Na > Li. The picrate flux depended on the type and number of oxyethylene units of the POE derivative. The highest flux was observed at a number of the units near 10. The picrate flux also increased with an increase in concentration of POE derivative. However, it was not proportional to the concentration. When the electromotive force across the membrane was maintained at 0 mV with a voltage clamp, the picrate flux decreased, and it increased with increasing membrane potential.