Preparation and characterisation of new microporous Elvaloy4170 coated PVDF membrane for desalination by air gap membrane distillation

Abstract

The demand to fabricate membranes much cheaper than usual expensive methods creates an opportunity to find low-cost and more available modifying agents for synthesising an appropriate membrane for membrane distillation (MD) process. In this work, reactive ethylene terpolymer was applied to modify a commercial polyvinylidene fluoride (PVDF) membrane for using in the desalination process. Elvaloy4170 with a hydrophobic structure containing three different functional groups was coated (different contents of 0.5, 1, 1.5 and 2 wt%) on the top surface of the microporous commercial PVDF membrane and the resultant membranes were analysed under air-gap MD process. The fabricated membrane structures were determined by scanning electron microscopy and atomic force microscopy to investigate their elemental and topographical properties. After experiments, the membrane with 1.5 wt% of Elvaloy4170 showed water vapour flux of 1.93 kg/m 2 h and salt rejection of >99.7 which confirmed its suitability to be used in the desalination process. Moreover, to assess the anti-fouling properties of the membranes, real seawater was used as feed solution, and as a result the membrane with 1.5 wt% of Elvaloy4170 presented flux recovery of 87% indicating its enhanced anti-fouling properties compared with the commercial PVDF membrane (flux recovery of 71%).