A CHARACTERIZATION OF PDMS PERVAPORATION MEMBRANES FOR THE REMOVAL OFTRACE ORGANIC FROM WATER

A new silicone pervaporation membrane for the removal of one of trace organics, 1,2-dichloroethane from water has been developed using polyd imethylsiloxane (PDMS) and oligomeric silylstyrene as a crosslinking a gent of PDMS. Optimal conditions for fabricating the best membrane wer e determined from swelling measurements and pervaporation experiments and then the membrane was characterized at different membrane thicknes s and operating conditions. In the pervaporation separation of 55-70 p pm of 1,2-dichloroethane aqueous mixtures, the developed membrane has flux of 2.5-330 g/(m(2) . h) and selectivity of 230-1750 depending on membrane thickness, permeate pressure and operating temperature. Water permeation through thin membrane was found to be subjected to signifi cant desorption resistance. while the desorption resistance and thermo dynamic factors as well as the concentration polarization of the organ ic at the boundary layer in feed can affect the organic permeation, de pending on membrane thickness. Selectivity change with permeate pressu re depends on membrane thickness: at small membrane thickness range, s electivity increases with permeate pressure and at large thickness reg ion it decreases. From the Arrhenius plots of each component fluxes, t he permeation activation energies were determined. Through an analysis of the permeation activation energies of each components. the desorpt ion resistance as well as the effects of the thermodynamic factors on permeation was qualitatively characterized.