New insights in the removal of diluted volatile organic compounds from dilute aqueous solution by pervaporation process

The present work aimed the mass transfer investigation in the removal of organic contaminants from water by the pervaporation process. The terpolymer ethene-propene-diene (EPDM) was used as the selective elastomer. Two classes of model organic solutes were chosen: chlorinated hydrocarbons (trichloroethylene, dichloromethane and trichloromethane) and aromatic ones (toluene, phenol and aniline). Pervaporation tests were carried out using dense and composite membranes with different thickness, solute concentrations and feed flow velocities at room temperature. The liquid boundary layer resistance (i.e., concentration polarization phenomenon) was observed for all solutes. The resistance-in-series model was used to determine liquid and polymer phase resistances. The results obtained indicate that the model would be better written considering the chemical potential gradient as driving force, in order to take into account affinity between water and the organic solutes, as well as their interactions with the polymer selective layer. The rational activity coefficients of the solutes in the polymer phase were determined by inverse gas chromatography (IGC) and related to the mass transfer coefficient in the polymer phase. (C) 1998 Elsevier Science B.V.