Transport of cadmium ions through a liquid membrane containing amine extractants as carriers

The comparison of the transport rates of Cd(II) from an aqueous feed chloride solution to an ammonium acetate strip solution through a bulk liquid membrane (BLM) consisting of tri-n-octylamine (TNOA) or tricapryl amine (N-235) as carriers in carbon tetrachloride solution was made. The influence of carrier concentration in the membrane, H+ and I- concentrations in the feed phase, and ammonium acetate concentration in the stripping phase was investigated. The optimal conditions for the transport of Cd(II) ions have been found. It is demonstrated that the transport of Cd(II) is coupled by co-transport flow of protons. The apparent extraction activation energies were found to be 4.5 kJ mol(-1) for TNOA and 6.8 kJ mol(-1) for N-235. respectively. The membrane permeability (P) of Cd(II) through a supported liquid membrane (SLM) was determined. The experiments show that TNOA carrier is better than N-235 in transport efficiency for Cd(II). (C) 2000 Elsevier Science B.V. All rights reserved.