Influence of the concentration boundary layers on membrane potential in a single-membrane system Original Research Article

The influence of the concentration boundary layers on membrane potential in a single-membrane system on basis of the Kedem-Katchalsky equations was described in cases of horizontally mounted neutral membrane separates mechanically stirred and unstirred binary electrolytic solutions at different concentrations. The measure of this influence is following expression ΔΨCBL = ΔΨm − ΔΨs, in which ΔΨm is a membrane potential in conditions of well-stirred solutions and ΔΨm – potential in conditions of unstirred solutions. Results of five sets of calculations were presented. In first the ΔΨCBL as a function of ratio solution concentrations (Ch/Cl) at constant value of concentration Rayleigh number (RC) was calculated, in second – the ΔΨCBL as a function of RC at constant of Ch/Cl, in third – the ΔΨCBL as a function of RC at constant concentration polarization coefficient (ζs), in fourth – the critical values of Rayleigh number (RC) crit as a function of ζs at constant of Ch/Cl and in fifth – the (ΔΨCBL)max as a function of ζs at constant of Ch/Cl. Calculations were made for the case where on a one side of the membrane aqueous solution of NaCl at steady concentration 10−3 mol 1−1 (Cl) was placed and on the other aqueous solutions of NaCl at concentrations from 10−3 mol 1−1−10−2mol 1−1 (Ch). Their densities were greater than NaCl solutionʹs at 10−3 mol 1−1. It was shown that voltage concentration boundary layers effect depends on hydrodynamic state of a complex concentration boundary layer–membrane–concentration boundary layer, what is controlled by RC and ζs.