Facile Synthesis of Highly Dispersed Ag Doped Graphene Oxide/Titanate Nanotubes as a Visible Light Photocatalytic Membrane for Water Treatment

Graphene oxide (GO) membranes have attracted extensive interest due to their ultrathin thickness, high flux, pore size tunability, superior flexibility, and energy-efficient properties for transporting ions and molecules through the unique 2D channels. Nevertheless, membrane fouling leading to membrane blocking and poor water flux of GO membranes during long-term use are major obstacles for water treatment or desalination applications. In this work, Ag doped GO/titanate nanotube (Ag/GO/TNT) membranes with enhanced visible light degradation ability were fabricated by a single-step procedure to resolve the fouling problem via integration of photocatalysis with membrane filtration. The results show that the Ag nanoparticles could be highly dispersed on the surface of GO and TNTs. And, the as-prepared Ag/GO/TNT membranes exhibited reasonable ability on photocatalytic degradation of Methylene Blue under visible light. We found that 90% of MB could be effectively degraded after 120 min irradiation with 8 mg of photocatalyst. More importantly, the membrane fouling could be effectively alleviated with visible light irradiation. In coupling the photocatalysis and membrane separation processes, the flux of Ag/GO/TNT membranes with the GO and TNT ratio at 1:3 and Ag content of 6% could be maintained at 34.7 L/m2 h which doubles that of membrane filtration without visible light irradiation. In addition, Ag/GO/TNT membranes possess high acid–alkali resistance stability and good compressive strength. These results have provided a simple preparation strategy to obtain highly dispersed nanoparticles and valuable insight into endowing membranes with visible light degradation ability for solving the problem of GO based membrane fouling.