Modeling of volatile organic compounds removal from water by pervaporation process

Pervaporation is a membrane technology utilizing a dense non-porous homogeneous polymeric film as a selective separation barrier. In recent years, pervaporation using dense membranes has emerged as a promising remediation method for trace organic removal from dilute aqueous solutions. The mathematical model commonly used to determine liquid and polymer phase resistances is the resistance-in-series model. In most studies the concentration or pressure gradient is considered as the driving force. In the present study a model was developed based on resistance-in-series model considering the chemical potential gradient as the true driving force in which the total resistance to mass transfer is defined as the sum of the liquid, membrane and vapor resistance. The model was validated by the experimental data available in the literature for various organic solutions and different membranes including PDMS and composite membranes. The results obtained show that the liquid phase boundary layer plays a significant rule in overall mass transport for all cases under study and ignoring this contribution could lead to a significant error in design and scale-up applications. It was also shown that the flux of permeating component is unaffected by the downstream pressure at low pressures up to 10 mmHg which indicates that for such systems the operating condition can be economically designed based on a moderate vacuum at downstream side instead of using a full expensive vacuum system.