Time evolution of NaCl flux through the microbial cellulose membrane with concentration polarization

The method of solute permeability coefficient and solute fluxes appointment for the membrane, based on monitoring of changes of conductivity of electrolyte solutions was presented. It was stated that during mechanical stirring of solutions the coefficient of NaCl permeability for microbial cellulose membrane (Biofill) did not depend on configuration of the membrane system and concentrations of solutions. Time characteristics of NaCl flux through the membrane Biofill oriented in horizontal plane were measured and modeled. The changes of NaCl fluxes through the membrane Biofill caused by concentration boundary layers build up on both sides of the membrane depended on NaCl concentrations and configuration of the membrane system. The differences between fluxes in different configurations of the membrane system were observed after time depended on initial concentrations in chambers. After that time, for configuration with solution with higher density over the membrane (configuration B) the NaCl flux through the membrane was greater than for configuration with solution with lower density over the membrane (configuration A). Besides it was stated that the coefficient of concentration polarization for configuration B was higher than for configuration A for all studied NaCl concentrations. Increase of mean concentration in the membrane at the initial moment caused increase (for configuration B) and lack of changes (for configuration A) of concentration polarization coefficient in the steady state of the membrane system. The interpretation of experimental results was made on the basis of Kedem-Katchalsky equations for the membrane system.