Effect of TiO2 content on the properties of polysulfone nanofiltration membranes modified with a layer of TiO2-graphene oxide

Graphene oxide (GO)-based membranes have been widely used for molecular separation due to their size exclusion effect. However, it remains a challenge to prepare a structurally stable, freestanding GO-based membrane that exhibits efficient separation. Herein, GO nanofiltration (NF) membranes with different loadings of TiO2 (TiO2@GO) were successfully prepared on top of a polysulfone (PSF) support layer and showed high efficiency in dye separation/desalination, along with antifouling and antibacterial activity. The resulting TiO2@GO NF membranes also showed excellent structural stability. The membrane prepared with the same contents of GO and TiO2 (NFG-2) exhibited high dye rejection (> 98%) and low Na2SO4 rejection (< 6%) and thus could be applied in the treatment of dye wastewater. Moreover, its permeation flux (3.6 L.m(-2).h(-1).bar(-1)) and dye rejection (98.0%) remained constant at high levels after 9 h of operation. Antifouling and antibacterial properties were also observed. This new kind of NF membrane may be a promising candidate for use in dye separation and desalination applications.