Effects of colloidal TiO2 and additives on the interfacial polymerization of thin film nanocomposite membranes

Highly stable, well suspended TiO2 nanoparticles (NPs) were synthesized by a sol-gel method and directly mixed with an aqueous amine solution to react at the interface with trimesoyl chloride, forming polyamide (PA) thin film nanocomposite (TFN) membranes with a uniform distribution of the nanoparticles in the PA film. Besides the presence of TiO2 NPs, the influence of remaining chemicals such as ethanol and acid from the synthesis of the TiO2 colloids on the film formation was also investigated. The residual ethanol and acid were found to play a role in thin film formation and properties of the final membranes. The presence of TiO2 NPs, ethanol, and acid had a positive impact on membrane wettability, water flux, and salt rejection. Compared to the unmodified membrane, the TiO2-TFN membranes achieved a good separation performance with around 12% and 19% improvement in water permeability and NaCl rejection, respectively. In addition, the developed TFN membranes possessed an improved anti-fouling property with low flux decay and high flux recovery up to 94%. This simple one-pot synthesis procedure of TiO2 NPs combined with the in-situ integration during the interfacial polymerization showed great potential for economic scaling up in industrial production of high-performance TFN membranes.