Carrier mediated transport through supported liquid membranes; determination of transport parameters from a single transport experiment

Abstract

This paper describes a time-dependent transport model for carrier assisted cation transport through supported liquid membranes. The model describes the flux of salt as a function of time and two parameters viz. the diffusion coefficient of the cation complex (D), and the extraction constant (K_ex). Simulations of transport experiments indicate that high extraction constants (K_ex) are responsible for the decrease in the transport rate in time.

A simulation program (CURSIM) was designed that is capable of determining the essential transport parameters D and K_ex from only one time-dependent transport experiment. The non-linear curve-fitting ‘Down-hill Simplex’ technique, gives directly the best-fit values of D and K_ex.

The CURSIM method was tested by evaluation of the transport of KClO₄ by different calix[4]arene-crown-5 carriers and by valinomycin. Comparison of the results with those obtained previously by the initial flux approach, which requires a series of different experiments, shows a good agreement of both methods.