PVDF Electrospun Nanofiber Membranes for Microfiltration: The Effect of Pore Size and Thickness on Membrane Performance

Microfiltration membranes are needed in waste water treatment, water purification and concentration processes. To separate microorganisms and suspended particles from process liquid, a contaminated fluid, especially water, is passed through a porous membrane. Electrospun nanofiber membranes could be used for this aim with their nanoscale fibers, small pore size, low weight and high permeability. The main purpose of this study is to show the relationship between the average fiber diameter and thickness of the PVDF nanofiber membrane and the pore size and liquid filtration efficiency. PVDF is a widely used polymer in water treatment processes. It is highly non-reactive thermoplastic fluoropolymer with outstanding physical and chemical properties. In this study, 16, 14 and 12% (w/v) PVDF nanofibers were produced electrospinning method to achieve three different mean diameter. 15 min, 30 min, 60 min, 3h and 5h of production periods were used for producing various thicknesses. According to pore size measurements, the differences in mean flow pore size (MFP) of 16PVDF and 14PVDF nanofiber membranes were not distinct. However, due to thin nanofiber diameter (278.58 nm) and high amount of nanofibers, the biggest pore size (FBP) of 12PVDF-5h was the smallest. There was also a significant difference between 12PVDF-5h and 12PVDF-3h, and FBP of these two membranes were smaller than the other three 12PVDF nanofiber membranes. Liquid filtration property of produced electrospun PVDF nanofibers was evaluated by turbidity rejection of a kaolin solution. In correlation with the pore size results, it was seen that best turbidity rejection % was belonging to 12PVDF-5h and worst was belonging to 16PVDF-15min nanofiber membranes. Nevertheless, all of the produced electrospun PVDF nanofiber membranes can be effectively used to remove contaminants from waste water at a relatively low cost