Investigation of parameters affecting the flux of microfiltration poly(vinylidenefluoride) membranes for particulate removal

The effects of membrane preparation conditions on characteristics of poly(vinylidenefluoride) (PVDF) microfiltration membranes dissolved in dimethylacetamide (DMAc) were studied. Influence of the casting thickness, coagulation bath temperature, evaporation time, and casting solution temperature on membrane performance and morphology was investigated. The flat-sheet membranes prepared by immersion precipitation technique were characterized using scanning electron microscopy (SEM). Membrane performance was evaluated by estimation of flux and rejection using blue indigo dye suspension as the feed. The results showed that by increasing the casting thickness, flux was initially improved due to the formation of more macrovoids. However, a further thickness increment leads to lower flux due to establishment of higher resistance against the water flow. Effect of the coagulation bath temperature and evaporation time on membrane morphology was particularly correlated to the temperature difference between the coagulation bath and the casting solution. For similar temperature of casting solution and coagulation bath, higher flux was observed for shorter evaporation time. However, higher flux was obtained for longer evaporation time when the temperature of casting solution and coagulation bath was dissimilar.