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

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 (Kex). Simulations of transport experiments indicate that high extraction constants (Kex) 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 Kex 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 Kex.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.