Polyethersulfone membranes: from ultrafiltration to nanofiltration via the incorporation of APTS functionalized-graphene oxide

•Polyethersulfone (PES) membranes comprising graphene oxide (GO) were prepared.•3-aminopropyltriethoxysilane functionalized GO (APTS-GO) fillers were added to PES.•Better rejections for dyes and salts were obtained for the mixed matrix membranes (MMMs).•A 6-fold increase in water flux was achieved by adding pore formers along APTS-GO.•A reduction in fouling propensity is obtained for membranes containing APTS-GO.