Facilitated transport of FeIII and CuII ions through supported liquid membranes

The factors that influence the transport of FeIII and CuII ions from a source to a receiving aqueous phase separated by an hydrophobic phase immobilized in the pores of a microfiltration membrane, i.e. the transport through a supported liquid membrane (SLM), have been investigated. The experiments were performed by transferring the ions from a sulfuric acid solution (feed) into a phosphoric acid solution (strip) through an n-decanol solution of the carrier, di-2-ethylhexyl phosphoric acid (D2EHPA), supported on a PVDF membrane. The results show that the transport rate through the SLM of both the ions increases with the D2EHPA content in the organic phase, the iron transport being mainly influenced by the acid concentration in the feed and that of copper by the acid content of the strip. The selectivity of the separation decreases with an increase of the acid concentration in the feed and with the increase of the permeated fraction. The observed results are explained under the assumption that the transport of FeIII is controlled by the diffusion of Fe–D2EHPA complex through the organic phase while the reaction with the carrier at the interface is the controlling step for the CuII transport.