Enhanced anti-fouling properties and chlorine resistance in TiO₂-QDs/C-dots modified thin-film nanocomposite reverse osmosis membranes

Due to the decrease in freshwater resources, the search for alternative clean water sources is rapidly increasing. One of these alternatives is desalination. Currently, reverse osmosis (RO) desalination facilities are widely utilized in countries with limited freshwater resources. However, fouling and chlorine sensitivity in RO membranes are significant challenges that reduce membrane lifespan and consequently increase operating costs. In recent years, carbon quantum dots have been extensively researched for their potential in anti-fouling and chlorine-resistant membrane fabrication as alternatives to traditional nanomaterials. In this study, innovative TiO₂ quantum dots/carbon dots (TQD/C-dots) were employed for the first time in the fabrication of high-flux brackish water RO membranes at concentrations of 0.001 wt%, 0.002 wt%, 0.005 wt%, 0.010 wt%, and 0.020 wt%. In the thin-film nanocomposite (TFN) RO membrane, incorporating 0.01 % TQD/C-dots by weight, the flux of NaCl solution was measured at 5.3 L·m⁻²·h⁻¹·bar⁻¹ (at 15.5 bar), with NaCl and boron rejections of 98.1 % and 58.6 %, respectively. Furthermore, the water contact angle decreased, and the flux recovery ratio improved from 63.5 % to 81.4 %, with augmented chlorine resistance in comparison to the unmodified RO membranes. Our results demonstrate that the incorporation of TQD/C-dots markedly diminishes organic fouling and enhances chlorine resistance in the TFN RO membranes.