Effect of paraffin and surfactant on coupled transport of cadmium(II) ionsthrough liquid membranes

The transport of Cd(II) ions from an aqueous feed chloride solution to an a mmonium acetate stripping solution through a supported liquid membrane cont aining tri-n-octylamine (TOA) in xylene has been examined. The influence of stirring rate, carrier concentration, stripping agent and H+ concentration in the feed solution was investigated. The transport of Cd(II) ions is cou pled by the co-transport of protons. The kinetics of transport could be ana lyzed in the formalism of two consecutive irreversible first-order reaction s, considering both extraction and stripping reactions. The pseudo-first-or der rate constants of interfacial reactions in membrane transport are deter mined with a bulk liquid membrane based on paraffin and the surfactant Span -80. The experimental results show that the effect of paraffin or surfactan t in the membrane is different for the interfacial reactions of extraction and shipping. (C) 2000 Elsevier Science B.V. All rights reserved.