Transport studies with model membrane

Abstract

The most recent theory for salt concentration dependence of biionic potential, developed by Ikeda and his colleagues on the basis of thermodynamics of irreversible processes, has been compared with that of Nozaki et al. to get a relationship for the calculation of theoretical values of biionic potential. The latter are in good agreement with the experimental data gathered for the parchment‐supported manganese ferricyanide membrane in contact with various alkali chloride solutions. The conclusion of selectivity sequence of group Ia cations, reached on the basis of measurements of biionic potentials, is consistent not only with the findings of thermodynamic effective fixed charge density, evaluated by utilizing membrane potential equations provided by nonequilibrium thermodynamics, but also with the data on activation parameters calculated by making use of the theory of absolute reaction rates. The values of impedance Z, membrane resistance Rm, and membrane capacitance Cm have also been evaluated on the basis of a simple equivalent circuit model. Impedance values follow the theoretical predictions at high frequencies, but at lower frequencies there is a marked deviation from the ideal behavior probably due to roughness and nonhomogeneity of the membrane used in this investigation.

Investigation of transport of glibenclamide drug across micro-pore supported model membrane using electro analytical methods

“…Study conducted in Ethiopia reported membrane potential increased with decrease in concentration (Damena et al, 2013) which was in line with the result of this study. There was also other study which supports this result (Saddiqi and Alvi, 1989). Variation of membrane conductance with increased drug concentration and temperature might be explained by taking the following points into consideration: The number of charged particles available for the transport of current; the extent of the sorption of permeants in the membrane phase; the variation of viscosity with concentration and temperature.…”

“…The other reason might be, when the hydrated ions approached to the pores of the membrane before effective interaction with phosphotidylcholine of the lipid, certain fraction of water molecules from the hydration shell of the ion and fixed sides might be removed. The negative entropy change of activation (-ΔS*) observed indicated that an ordered water molecules become less ordered in the most diluted solutions (Saddiqi and Alvi, 1989). Study conducted in India on ion transport studies through polystyrene based model membrane conductance data and absolute reaction rate theory reported activation energy decrease with increase in concentration and the value of change of entropy were negative.…”

“…Membrane conductance (π) data was used to evaluate (∆H*) and (∆S*), respectively, from the slope and intercept of linear plot of ln (πNh/RT) against 1/T in accordance with Equation 2.The evaluated activation parameters would be used to evaluate Arrhenius activation energy (Ea) and activation free energy (∆G*) in accordance with the following relations (Kotwal and Thube, 2007;Siddiqi et al, 1988;Saddiqi and Alvi, 1989).…”

Non Stationary Ionic Current through Polymer Charged Membrane

“…On the other hand the amount of variation in the current was found to be depend on the many factors, such as applied potential, diffusion coefficient, initial concentration of components within membrane, the resting potential and the initial and final steady fluxes, in more complicated manner. 15 In order to estimate the flux at resting state, the following equation could be available; 16 (27) where C 0 α and C l α are bulk concentrations of ion α on the both sides of membrane and Pα is the membrane permeability to the ion α. Assuming that in the membrane, the potential gradient is a constant and the diffusion coefficient, Dα is a constant independent of concentration Pα may be reduced to (28) which, provided zαFV / 2RT, is small as compared with unity, is reduced to (29) where η α indicates excess free energy of the ion α. Inserting equation (29) into equation (27), we obtain the next equation (30) (30) Thus the fluxes at rest and the diffusion coefficients could be estimated from the data shown in Table 1.…”