Electrospun nanofibrous polysulfone membranes as pre-filters: Particulate removal

This paper explores the viability of developing high surface area pre-filters through electrospinning. Pre-filters are regularly used in removing particulate contaminants that can have a deleterious effect on downstream membrane elements such as ultrafiltration and nanofiltration. They should possess high internal surface area and thus sub-micron size fibers are ideal. In this study, polysulfone nanofibers were electrospun into membranes and their ability to remove micro-particles from solution was investigated. The nanofibrous membranes possess high porosity together with high surface area to produce high flux pre-filters with high loading capacity. The membrane had a bubble-point of 4.6 μm and was able to remove above 99% of 10, 8 and 7 μm particles without any permanent fouling. However, the membrane was observed to foul irreversibly by 2 and 1 μm particles with a ‘cake-layer’ forming on the membrane surface. Below 1 μm, the membrane behaved as a depth filter with 0.5 and 0.1 μm particles being attracted onto the nanofiber surface. This study highlights that nanofibers do have potential as pre-filters for particulate removal. Such nanofibrous pre-filters can be used in various applications such as removal of micro-particles from waste-water, prior to ultrafiltration or nanofiltration membranes, to prolong the life of these membranes.