Molecular design of the morphology and pore size of PVDF hollow fiber membranes for ethanol-water separation employing the modified pore-flow concept

► Increasing air-gap/take-up results in reduced pore size and pore size distribution. ► A correlation on pore size and separation is in line with modified pore-flow model. ► The surface flow is more prevailing mechanism in smaller pores. ► The Knudsen flow is more prevailing mechanism in bigger pores. ► Membranes have separation factors of 5-8 and total fluxes of 3500-8800 g m−2 h−1.