SURFACE IMPROVEMENT AND MODIFICATION OF PDMS.SIO2/PES MEMBRANE FOR ETHANOL/WATER SEPARATION IN MEMBRANE BIOREACTOR

Abstract

An ethanol selective composite membrane consists of dense and hydrophobic polydimethylsiloxane (PDMS) as active layer on polyethersulfone (PES) as support layer was successfully fabricated. In order to improve membrane's ethanol selectivity, SiO2 was coated on the surface of composite membrane. For SiO2 coating, the composite PDMS surface was modified by corona treatment at corona time of 6 min and corona input power of 360 W. As a result, the ethanol separation factor has significantly increased (from 6.9 to 10.5 for total flux of 510 g/m2.h). The ethanol separation factor using PDMS/PES modified surface membrane was improved by 52%. In the next step, the performance of the fabricated PDMS.SiO2/PES membrane was examined in membrane bioreactor (MBR). Based on obtained data, bioethanol concentration in conventional fermentation was 18.9 g/l while bioethanol concentration in broth of MBR and cold trap were 23.54 and 195.4 g/l, respectively. In addition, the cell concentration at conventional fermentation was 12.3 g/l. The cell concentration in MBR using the PDMS fabricated membrane has reached to 16.1 g/l. Therefore, the modified fabricated composite PDMS.SiO2/PES membrane was quite effective for ethanol separation. The fabricated composite PDMS membrane was much superior than the commercial PDMS membrane