Formation of polymeric membranes by immersion precipitation: an improved algorithm for mass transfer calculations

This note describes an improved algorithm for the solution of the governing equations describing ternary mass transfer during the quench-period in the formation of immersion precipitation membranes. The algorithm is applied to the model developed by Reuvers et al. (J. Membr. Sci. 34 (1987) 45) for the water–acetone–cellulose acetate system. The improved algorithm developed in this work numerically simulates the multi component unsteady state diffusion process in immersion precipitation membrane formation without the necessity of user intervention in terms of initial guesses for the interfacial composition. Phase separation is assumed to take place at the spinodal. The algorithm is presented in detail for three component systems, however, it is easily extendable to four component systems. Numerical simulations using the improved algorithm are in good agreement with those of Reuvers et al. (J. Membr. Sci. 34 (1987) 45), however, experimental studies are required to validate some of the assumptions relating to the polymer phase separation.