RATE-CONTROLLING MECHANISM OF COBALT TRANSPORT THROUGH SUPPORTED LIQUID MEMBRANES CONTAINING DI(2-ETHYLHEXYL)PHOSPHORIC ACID

In this paper the permeation process of trace cobalt(II) through suppo rted liquid membranes using di(2-ethylhexyl)phosphoric acid as a mobil e carrier was modeled and the rate-controlling mechanism was examined. The permeation rate equations were derived considering diffusion of m etal ions across the aqueous stagnant layers toward the membrane, chem ical reaction at the feed-membrane interface, and diffusion of extract ant and its metal complex in the membrane phase. The application of th e measured permeation rates for determining the kinetic parameters of the solvent extraction reaction was also investigated. It was found th at the calculated rates were in good agreement with the measured ones (average standard error, 12%).