Abstract: The effects of stirring rate, stripping agent, tri-n-octylamine concentration, initial concentrations of H⁺ions in the feed phase on transport flux of Cd(Ⅱ) ions across a tri-n-octylamine xylene supported liquid membrane were studied. The pseudo-first-order rate constants, k₁ and k₂, of the interfacial reactions on the feed and the stripping side membrane face were determined in bulk liquid membrane. The experimental results show that k₁ and k₂ increase with an increase of temperature and k₁> k₂. The t_max decreases with a corresponding raising of temperature. The transport of Cd(Ⅱ) across membrane is in steady state when the concentration of Cd(Ⅱ) in membrane is maximum value. The apparent activation energies were found to be 23.8 kJ/mol for extraction and 19.3 kJ/mol for stripping extraction in the liquid membrane system according to Arrhenius equation, respectively.

Key words: Bulk liquid membrane, Cadmium ions, Tri-n-octylamine, Reaction rate constant