Material transport in hyperfiltration

Abstract

Transport equations for hyperfiltration, based on the frictional formalism of non-equilibrium thermodynamics, are derived for a gel-type membrane. Taking the concentration distribution in the membrane into account and allowing for possible non-equilibrium partition effects at the membrane boundaries, the flow equations are integrated and equations for solute rejection in dilute solutions are derived. It is shown that the main parameters determining solute rejection are the solute partition coefficient on the high-pressure side of the membrane and a frictional factor, involving the solute and solvent friction coefficients. Partition effects on the low-pressure side are unimportant for processes at high flow rates.