Electrospun polyimide fiber membranes for separation of oil-in-water emulsions

Abstract

• Fouling is a persistent problem in microfiltration of oil/water emulsions. • Electrospun P84 polyimide membranes separate oil/water emulsions efficiently. • Resistance to fouling is due to the oleophobic character of P84. • Membrane performance is completely regenerated by thermal treatment. The separation of emulsified oils from water represents a significant challenge for water reclamation and clean-up, because such droplets remain suspended for long periods of time. Membrane technology offers a solution to such separations, but its major drawback is the requirement for frequent cleaning to remove foulants, which reduces membrane lifetime and incurs additional economic and environmental costs. To address this shortcoming, we examine the separation performance of fibrous membranes of P84 polyimide, a copolymer known for its thermal stability and chemical resistance, fabricated by electrospinning technology. The P84 membranes were challenged by surfactant-stabilized emulsions of dodecane or motor oil in a constant pressure dead-end configuration. The P84 membranes exhibited moderate oil rejections between 85 and 90%, while subsequent foulant removal by heat treatment restored permeate fluxes to essentially 100% of their original values. A comparison of P84 membranes to other common membrane polymers with respect to robustness against fouling shows that the P84 membranes have some advantages, which we attribute to the oleophobic nature of the P84 membrane, as well as the ease of membrane regeneration. These results indicate that the electrospun P84 membrane is a promising candidate for microfiltration of water contaminated by emulsified oil.