A 2-DIMENSIONAL MODEL FOR EQUILIBRIUM PARTITIONING OF A FLUID MIXTURETHROUGH A MICROPOROUS SEMIPERMEABLE CRYSTALLINE MEMBRANE - A MONTE-CARLO STUDY

We have considered a simple two-dimensional model for a system consist ing of a two-component mixture of hard discs on one side of a micropor ous slit-like semipermeable membrane and one-component fluid of discs on the other side. The particles of a slit-like membrane are fixed acc ording to either (11) or (10) crystal symmetry. The distance between t hese particles is chosen such that only one fluid component can permea te the membrane. Osmotic equilibrium in the system is then established . The entire system is confined, for technical convenience, to a wide slit-like pore with the membrane in the center. The walls of the wide pore are distanced from the external surfaces of the membrane to provi de the bulk region where the density profiles appear to be constant. M onte Carlo canonical simulation results are presented for the density distributions of the fluid particles in the entire wide pore. We have observed that partitioning of the smaller particles essentially depend s on the concentration of the larger particles on one side of the memb rane. The osmotic pressure is calculated from the contact values of th e density profiles on the walls of a wide pore using the contact theor em. The pressure also has been obtained via Boublik's equation of stat e for a mixture of hard discs using the bulk densities of species obta ined from simulations. The values for the partition coefficients on th e osmotic pressure are discussed, (C) 1998 Academic Press.