Omniphobic Braid-Reinforced Hollow Fiber Membranes for Dcmd of Oilfield Produced Water: Understanding the Effect of Process Conditions on Membrane Performance

Recent efforts to realize hollow fiber membranes for treatment of complex wastewater such as produced water has resulted in designing unique surfaces, for use in membrane distillation to combat wetting and fouling/scaling. However, HFMs suffer from mechanical inadequacies. Use of polyethylene terephthalate (PET) braid support to strengthen HFMs is gaining attraction, although their application in MD is scarce. Herein, we report omniphobic PET braid-reinforced HFMs (OBRMs) for application in direct contact membrane distillation (DCMD) of PW. The effects of feed type, velocity, temperature, and prolonged testing on performance OBRMs are reported. From the findings, a thin polymer layer with single-layer finger-like structure allowed for good flux (up to 15 kg/m 2 h) while omniphobic skin layer was instrumental in keeping oils and surfactants at bay. Complex PW feed is shown to have more adverse effect on strength of OBRMs than saltwater. Increased temperature negatively affects tensile strength while a turbulent flow keeps foulants at bay and mitigates fouling-assisted deterioration. Prolonged testing for nine DCMD cycles of treating PW recorded flux recovery up to 85%, with salt rejection remaining above 99.9%, a total organic carbon (TOC) rejection up to 98% and a decline in tensile strength of used membranes by 6.5%.