Fabrication of PDMS based membranes with improved separation efficiency in hydrophobic pervaporation

PDMS based membranes were prepared using various modification approaches. Structural and surface properties of prepared membranes were investigated applying a number of instrumental techniques (AFM, FT-IR, DSC, SEM, CA). Finally, transport and separation properties of the developed membranes were determined during pervaporation (PV) experiments in contact with water and water-ethanol mixture. The results were compared with efficiency of the native and commercial PDMS based membrane. Applied preparation procedures resulted in creation of membranes possessing different morphology and pervaporative performance, e.g. modification of membrane matrix with salt method resulted in smaller crosslinking ratio of poly(dimethyl siloxane) sample comparing with pristine PDMS membrane. Whereas, plasma treatment of PDMS sample caused reduction of hydrophobic properties of PDMS membrane resulting in much lower separation factor (beta = 6.0). PV results showed that PDMS_NaCl (beta = 10.5) and PDMS Al2O3_mod.C8 (beta = 10.8) possessed the most selective properties towards organics among all PDMS based membranes tested in this study, showing that salt method and filling of poly(dimethylsiloxane) matrix with triethoxy(octyl)silane (C8) modified Al2O3 allowed to obtain improved membranes performance in hydrophobic pervaporation.