Investigating the efficiency of g-C₃N₄/TiO₂/CQD nanocomposite on improving the performance and antifouling of polyvinyl chloride membrane in drug and dye removal under visible-light radiation

In this paper, novel g-C₃N₄/TiO₂/CQD/EPVC photocatalytic membranes were manufactured via the phase inversion procedure, and their performance was studied during a combined membrane filtration/photocatalytic process via visible-light radiation. The purpose of adding a photocatalyst to the membrane was to improve the permeability, the antifouling properties, and the separation efficiency of the PVC membrane. The fabricated membranes were recognized using AFM, SEM, zeta potential, porosity, average pore radius, and contact angle measurements. The modified membranes showed high multi-purpose performance compared to the bare membrane. Owing to the existence of hydrophilic functional groups on g-C₃N₄/TiO₂/CQD, the modified membranes had great permeability, hydrophilicity, and consequently water flux. The photocatalytic process, by degrading pollutants and sediments in the presence of light, resulted in high antifouling characteristics of the membrane and increased flux recovery ratio (FRR). The membrane containing 1 wt% g-C₃N₄/TiO₂/CQD as the optimized membrane showed the highest multiple performances, namely photocatalytic oxidation, flux rate, separation, stability, FRR, and significant antifouling properties. According to the obtained results, the water flux enhanced from 282.8 L/m².h for the bare membrane to 547.3 L/m².h for the 1 wt% g-C₃N₄/TiO₂/CQD membrane. The rejection rates of BSA, Cefixime, Azithromycin, Lanasol Red 6G, and Reactive Black 5 (RB5) for the optimized membrane were 99.8 %, 73.09 %, 88.62 %, 86.24 % and 91.02 %, respectively. The observation results exhibit that the g-C₃N₄/TiO₂/CQD photocatalyst as an excellent additive remarkably enhances the efficiency of PVC membranes. This membrane, with its multifunctional properties, has promising potential in water purification.