Membrane diffusion and flux response Original Research Article

A linear diffusion convection equation for the transport of a single chemical component through a membrane is coupled with a linear reaction equation describing interaction of the diffusing chemical with an immobile reactant. Expressions are derived for the flux responses in and out of the membrane to given concentrations applied at one side of the membrane while zero concentration is maintained at the other. These fluxes are compared with the corresponding fluxes for the complementary experiment in which the imposed boundary concentration at the two faces of the membrane are interchanged. Ussing-type flux-ratio relationships are obtained for the outflow fluxes, but the inflow fluxes respond in a different way, and it is found that the difference of the influxes for complementary experiments remain constant for all time.