Quantitative evaluation of concentration polarization in the permeation of VOCs/water mixtures through PDMS membrane using model equation

The influence of concentration polarization on the pervaporation and separation of VOCs/water mixtures through the PDMS membrane was investigated, using model equation based on the resistance-in-series concept in the boundary layer in feed adjacent to the membrane surface. Dichloromethane, chloroform, 1,2-dichloroethane, and 1,1,2-trichloroethane were used as VOCs. From the permeation data of the mixtures, the overall mass transfer coefficient, mass transfer coefficient of VOCs component across the boundary layer and concentration polarization modulus as a measure of extent of concentration polarization were determined quantitatively with help of the model equations. From the analysis on the determined model parameters, the boundary layer resistance due to the concentration polarization of VOCs component contributed more to the overall permeation process than the membrane resistance did.