A numerical simulation for the prediction of flux and rejection during ultrafiltration in unstirred batch cell using variable diffusivity concept

A three-parameter model based on unsteady state mass transfer has been deve loped for the prediction of flux and rejection during ultrafiltration in un stirred batch cell, Once the three parameters, viz. membrane hydraulic resi stance, solute permeability and reflection coefficient, have been ascertain ed for a particular membrane-sol Lite combination. the flux and rejection c ould be predicted at any operating condition. The main feature of this mode l is that it allowed variation of solute diffusivity with concentration in the boundary layer whose effect is more pronounced in the case of unstirred batch cell. Orthogonal collocation on finite element (OCFE) technique has been used to solve the resulting non-linear partial differential equation, coupled with an equation from irreversible thermodynamics. Average deviatio n between theoretical results and the experimental data generated in this s tudy is found to remain within +/- 5%. (C) 2000 Elsevier Science BN. All ri ghts reserved.