Nonsteady State Vs Steady-state Kinetic-analysis of Coupled Ion-transport Through Binary-liquid Membranes

Coupled transport of copper (II) ions through binary liquid membranes of variable composition was investigated using n-octane and mesitylene as membrane components. Rigorous kinetic analysis (non-steady state regime) based on a scheme implying two consecutive irreversible first order reactions could be realized in each case. The experimental data were analysed also in the steady state approximation by using both empirical and theoretical approaches. A new analytical expression was derived for the characteristic time lag. Appropriate criteria have been established for the applicability of steady state approximation when comparison of different transport systems is envisaged. It was also established that the competitive preferential solvation theory can be applied successfully to coupled ion transport processes.