Fabrication and characterization of metakaolin based flat sheet membrane for membrane distillation

Abstract

A low-cost flat sheet kaolin/metakaolin membrane was fabricated via a combined using phase inversion and sintering methods at different kaolin/metakaolin content and sintering temperature. The ceramic suspension with suitable viscosity was prepared by mixing the kaolin/metakaolin powder, Polyethersulfone(PESf) as a binder, N-methyl-2-pyrrolidone(NMP) as solvent and Polyvinylpyrrolidone(PVP) as a dispersant. The membrane precursor was then sintered in a controlled furnace to target temperature of 1200 ℃,1300 ℃, 1400 ℃ and 1500 ℃. Then, the surface of the kaolin/metakaolin membrane was modified by 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PFAS). Finally, the ceramic membrane was characterized using a scanning electron microscope (SEM) and a contact angle analyzer. It was found that by varying the kaolin/metakaolin contents and sintering temperatures; different surface morphologies of flat sheet membranes were obtained. Moreover, the successful grafting with PFAS was evidenced by the increase in contact angle from nearly equal to 3.7° to 142°. Thus, it can be generally concluded that the metakaolin based flat sheet membrane has desirable characteristics for membrane distillation applications in terms of hydrophobic effect and chemical stability (<1% weight loss).