Plasma surface modification of graphene oxide nanosheets and their usage in the production of ultrafiltration membranes for oil-water separation

In this work, an environmentally friendly surface modification method based on plasma enhanced chemical vapor deposition (PECVD) was employed to deposit functional polymeric thin films onto graphene oxide (GO) nanosheets which were subsequently used to develop ultrafiltration (UF) membrane with improved surface properties for oily solution treatment. Two different monomers, namely hexafluorobutyl acrylate (HFBA) and diethylaminoethyl methacrylate (DEAEMA) were individually used to modify GO via PECVD method and the results from instrumental analyses confirmed the successful deposition of respective functional material onto the nanomaterials. All the developed membranes were characterized with a series of analytical instruments to support the findings of membrane filtration performance. The results indicated that the membrane incorporated with DEAEMA-GO (coated with hydrophilic polymer) could achieve better results in terms of oil rejection, antifouling resistance and water recovery rate than the membrane incorporated with HFBA-GO (coated with hydrophobic polymer). This is due to the reduced agglomeration between modified GOs as well as better interaction of hydrophilic-coated GOs with polymer membrane. Compared to the pure water flux of the membrane incorporated with unmodified GO, the membrane incorporated with DEAEMA-GO achieve approximately 85% higher value with oil removal rate remained almost unchanged. Keywords: PECVD, Graphene Oxide, Ultrafiltration, Oil/Water Separation, Surface Modification