PREPARATION OF A HYDROPHOBIC AND MICROPOROUS MEMBRANE FOR MEMBRANE DISTILLATION USING THE DRY-WET PHASE INVERSION TECHNIQUE

PREPARATION OF A HYDROPHOBIC AND MICROPOROUS MEMBRANE FOR MEMBRANE DISTILLATION USING THE DRY-WET PHASE INVERSION TECHNIQUEIn recent years, membrane distillation (MD) has been increasingly explored for seawater desalination to augment fresh water supply around the world and in Vietnam. In a MD system, the hydrophobic microporous membrane plays a vital role, profoundly affecting the water flux and salt rejection of the system. In this study, poly vinylidene difluoride (PVDF)-based hydrophobic microporous MD membranes were prepared using the dry-wet phase inversion technique to investigate the effects of the preparation conditions on the membrane structure and surface morphology. The experimental results show that by using the dry-wet phase inversion technique, the prepared PVDF membranes existed in crystal forms of a and b, and the casting polymer solution temperature and the ambient moisture exhibited profound effects on the formation of crystals and the membrane porosity. Indeed, reducing the polymer solution temperature and the ambient moisture favoured the formation of the b crystals and the resultant cellular membranes. Finally, morphological analyses (e.g. microscope, scanning electro microscope (SEM), and contact angle measurement) proved that the prepared MD membranes using the dry-wet phase inversion technique were hydrophobic and microporous, having a liquid-membrane surface contact angle of 121°-125° and membrane pores with mm sizes.