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 t o the model developed by Reuvers et al. (J. Membr. Sci. 34 (1987) 45) for t he water-acetone-cellulose acetate system. The improved algorithm developed in this work numerically simulates the multi component unsteady state diff usion process in immersion precipitation membrane formation without the nec essity of user intervention in terms of initial guesses for the interfacial composition. Phase separation is assumed to take place at the spinodal. Th e algorithm is presented in detail fur three component systems, however, it is easily extendable to four component systems. Numerical simulations usin g the improved algorithm are in good agreement with those of Reuvers et al. (J. Membr Sci. 34 (1987) 45), however, experimental studies are required t o validate some of the assumptions relating to the polymer phase separation .