Vapor permeation modeling of multi-component systems using a poly(dimethylsiloxane) membrane

This study examined the simultaneous removal and recovery of volatile organic compounds (VOCs) from permanent gaseous streams using a vapor permeation (VP) technique. The VOC fluxes in multi-component feed systems were predicted using a poly(dimethylsiloxane) (PDMS) membrane in the VP process. The investigated vapors included methanol, toluene, m-xylene, iso-pentane, and water. The solution-diffusion model derived from Fick's first law was used in establishing the mathematical models to describe the vapor permeation flux as a function of the downstream pressure and vapor activity level. The upstream sorption concentration was predicted using the multi-component UNIQUAC equations. The vapor diffusion coefficient was determined employing Long's model. The results demonstrated that the estimated vapor permeation fluxes were in good agreement with the experimental data. No diffusivity coupling terms were needed in the mass transfer equations for the VP of multi-component feed systems. Therefore, the diffusivity parameters established from single-component vapor systems can be extended to multi-component feed systems. This finding allows the simplification of the mass transport modeling.