Emulsion Transport Through Graphene Oxide Modified Polyvinylidene Fluoride (PVDF) Membranes

Graphene oxide (GO) is an exceptionally hydrophilic 2D nanomaterial with an ultrahigh specific area, which has demonstrated exceptional antifouling properties from oil. Coating patent no. WO2019106344A1 by G2O Water Technologies Limited suggests the merit of using GO in relevant applications. However, the benefit of using a hydrophilic polyvinylidene fluoride (PVDF) microfiltration membrane as backing materials for GO has not been tested. Therefore, 0.22 µm PVDF hydrophilic flat sheet microfiltration membrane substrates were coated by G2O’s patented method producing 7.5 nm, 15 nm and 30 nm GO-coated membranes with a diameter of 40 mm. Hexadecane-Sodium Dodecyl Sulfate-Water emulsion treated the membranes at 1 bar in a dead-end cell. Scanning electron microscope, KSV pendant drop and attenuated total reflectance infrared spectroscopy characterized the surface morphology, water contact angle, and graphene oxide performance. The performance of an unwetted 7.5 nm GO-PVDF membrane outperformed the wetted modified membranes. Despite GO self-catalyzation, the dissociation of sodium dodecyl sulfate and hexadecane coalescence was of ten times their original size during filtration. The modified membrane exhibited a 33% increase in permeate flux and 73.0% oil rejection. This performance indicated that the coating method is capable of withstanding fouling without regular backflushing or chemical clean-in-place.