Thin film nanocomposite reverse osmosis membrane modified by reduced graphene oxide/TiO₂ with improved desalination performance

A novel thin film nanocomposite reverse osmosis (TFN-RO) membrane was prepared by interfacial polymerization of m-phenylenediamine (MPD) and trimesoyl chloride (TMC) monomers and embedding reduced graphene oxide (rGO)/TiO₂ nanocomposite in its polyamide layer. The rGO/TiO₂ nanocomposite was added to the MPD solution with aim of improving RO performance, enhancing antifouling property and increasing chlorine resistance. Surface scanning electron microscopy (SEM) images show that all of the membranes have a rough surface with a layer of "ridge-and-valley" structure that is typical morphology of MPD/TMC polyamide membranes. The contact angle analysis showed that hydrophilicity of the membranes was improved by increasing the concentration of rGO/TiO₂ due to the presence of various hydrophilic and negatively charged functional groups on the rGO/TiO₂ nanocomposite. The superior performance of the rGO/TiO₂/RO membrane was observed in the case of 0.02wt% rGO/TiO₂ with water flux of 51.3L/m²h and salt rejection of 99.45%. Antifouling ability of the membranes studied by bovine serum albumin (BSA) solution filtration showed that 0.02wt% rGO/TiO₂/RO membrane had the best antifouling property. Also, after the chlorination tests, the salt rejection of the bare RO membrane decreased by 30%, while this value was only 3% for 0.02wt% rGO/TiO₂/RO membrane which confirmed its great chlorine resistance.