Donnan-membrane effects in hyperfiltration of ternary systems

Abstract

When aqueous solutions are forced through membranes by the application of pressure, as in hyperfiltration, the presence of a membrane-impermeable ion in the pressurized solution can markedly affect the transport of co-ions through the membrane. This effect is demonstrated experimentally with several types of membrane and found to be general. A simple model is developed to describe the observations. The model is an extension of Donnan's original equilibrium treatment to the non-equilibrium situation occurring in hyperfiltration.