THE CORRELATION OF MEMBRANE PERMSELECTIVITY WITH HILDEBRAND SOLUBILITY PARAMETERS

Experimental and theoretical permselectivities for a filled elastomeric membrane have been correlated utilizing Hildebrand solubility parameters in a solution-diffusion model. Equilibrium partitioning of substances between the feed and membrane phases may be modelled as solutions. These two phases may be thermodynamically characterized by means of the Hildebrand solubility parameters. In addition, the effect on diffusive transport of the partitioning of a substance between a filler and polymer phase in a membrane may be correlated to solubility parameters. A variety of substances was examined in this study using a silicone elastomer membrane, composed of 69 wt% poly(dimethylsiloxane) and 31 wt% fumed silica. The model is demonstrated to have good predictive value over three or four orders of magnitude for the permselectivities of substances including permanent gases, alkanes, chlorinated and brominated hydrocarbons, alcohols, and aromatic hydrocarbons.