Modeling of cross-flow osmotic pressure controlled membrane separation processes under turbulent flow conditions

A comprehensive predictive model for the osmotic pressure controlled turbulent cross-flow membrane separation process is presented. A thin rectangular channel is selected as the system geometry. The model can handle solutes with wide range of diffusivities (from sodium chloride to dextran) under different modes of membrane separations (RO, UF, etc.). It is not limited to the condition that the mass transfer boundary layer lies within the viscous sublayer of the hydrodynamic boundary layer. The governing equations are solved using an integral method. The performance characteristics of the system in terms of permeate flux and permeate concentration can be predicted simultaneously. The experimental data available in the literature under turbulent conditions [Ind. Eng. Chem. Fundam. 3 (1964) 210; J. Membr. Sci. 22 (1985) 117] are successfully compared with the model predicted results. A parametric study has been carried out to observe the effects of various operating conditions on the permeate flux and permeate concentration (in terms of observed retention).