Facile Fabrication of Unimpeded and Stable Graphene Oxide Coating on Reverse Osmosis Membrane for Dual‐Functional Protection

Membrane fouling and chlorination have remained the greatest threats to durable reverse osmosis (RO) membrane applications. Here, we report a facile technique of high pressure assisted deposition (HPSD) to physically anchor stable graphene oxide (GO) coatings on RO membranes for simultaneous dual-functional protection against fouling and chlorination without sacrifice of water flux. Thick coatings were directly prepared by HPSD, and a subsequent “skin-removing” method was used to obtain GO thin coatings with stronger adhesion. The measurement of GO coating thickness was achieved by a “removing-transferring” method, demonstrating a thickness of 200 and 50 nm for GO thick and thin coatings, respectively. Benefiting from our coating deposition technique of HPSD, 100% of coverage by GO was achieved for both GO coated membranes. The filtration test showed that GO coating was highly permeable to water resulted from the optimized small size of GO sheets (∼200 nm) and the unique water transport properties through GO laminates. The GO thin coating could effectively alleviate the membrane fouling by rendering membrane surface more hydrophilic and smoother, while the thick coating reversely aggravated the fouling due to the more hydrophobic surface. In addition, GO coating could dramatically improve the chlorine stability of RO membrane by impeding the diffusion of reactive chlorine, with a high level of salt rejection after chlorination for GO coated membranes.