(335b) Thermally Stable Electrospun Polyimide Fiber Membranes for Separation of Oil-in-Water Emulsions

One of the major drawbacks of polymeric membranes applied to the treatment of oily wastewater is that the membranes have relatively poor thermal stabilities and chemical resistance. Due to membrane fouling, frequent foulant removal processes becomes necessary, which reduce the lifetime of the polymeric membrane and incur additional economic and environmental costs. Therefore, there is a need to improve membrane stability and fouling resistance for this clean and relatively cheap technology to advance. In this work we report the use of electrospinning technology, which has been shown to produce membranes with improved robustness against fouling, to generate fibrous membranes made of P84 polyimide, a co-polymer known for its thermal stability and excellent chemical resistance. The P84 membranes were challenged by emulsions of dodecane and motor oil in water, stabilized by sodium dodecyl sulfate (SDS), in a constant pressure dead-end configuration. The resultant flux, oil rejection, sensitivity to fouling, and flux recovery were evaluated. When challenged by dodecane and motor oil, the P84 membranes exhibited moderate oil rejections of 86.6 ± 1.5 % and 88.0 ± 2.4 %, respectively, while subsequent foulant removal by heat treatment restored permeate fluxes to 108 ± 15 % and 93 ± 17 % of their original values. A comparison of P84 membranes to PVDF, PSF and PA6(3)T membranes shows that the P84 membranes have the best robustness against fouling, which is attributed to electrostatic repulsions and the oleophobic nature of the P84 membrane, as well as the ease with which such membranes can be regenerated. These results indicate that the electrospun P84 membrane is a promising candidate for microfiltration used in the treatment of water contaminated by emulsified oil.