Graphene oxide(GO)membranes for nanofiltration have been studied recently with room for improvement in salt rejection,cross-flow shear resistance,scalability,chlorine resistance,among other themes.^ Previous reports have shown GO membranes operating in static cells,dead end flow and cross flow systems.The latter,is widely used for large scale clean water output;;based on applying high pressure(5 MPa)with a water feed flowing on the membrane surface.The majority of the reported GO membranes rely on dead end flow measurements and very few on cross flow,due to the low water shear resistance.2)For cross flow shear stability,carbon nanotubes(CNTs)have been introduced in the GO membrane,2)however CNTs are much larger than the size of hydrated ions therefore high salt rejection is not expected.For high salt rejection,vertically aligned GO has achieved salt rejection above 90%,however for a static cell due to the extremely low mechanical stability under pressure and difficulty in membrane preparation.3* Therefore,an easy and scalable method for graphene preparation is highly desirable,for this spray-coating could be feasible.
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