Effect of Surface Roughness on the Pervaporative Performance of PDMS/PES Composite Membranes for Ethanol / Water Separation

Composite membranes with the same active layer of PDMS and different support layers based on PES and hydrophilic additives, PVP/ PEG/ SiO2/ NaCl, were prepared. Surface morphology ofmembranes before and after compositing by PDMS layer, were investigated by AFM images. Mean surface roughness of support and composite membranes were measured. The outcomes indicated that composite membranes had lesser surface roughness than their supports. It proved that active layer covered the sublayers appropriately. The minimal surface roughness appeared inPDMS/PES.PEG membrane. The effect of surface roughness on the hydrophobicity of an inherently hydrophobic surface was expressed. Whereas PDMS membrane is a well-knownhydrophobic membrane, surface of PDMS/PES.PEG membrane became more hydrophilic than others. The effect of surface roughness on the pervaporation performance of compositemembranes for separation of ethanol from aqueous solution was evaluated. It was revealed from the results that PDMS/PES.PEG membrane represnted the foremost total permeation flux with the value of 307.69 (gr/m2.hr) while it preserved the reasonable separation factor

Keywords:

Pervaporation , PDMS/ PES composite membrane , Surface Roughness , Ethanol