Novel nitrogen and sulphur co-doped carbon quantum dots/titanium oxide photocatalytic membrane for in-situ degradation and removal of pharmaceutical compound

In this study, a novel photocatalytic membrane had been successfully fabricated through the incorporation of N,S-CQDs/TiO2 nanocomposite on polysulfone (PSF) membrane for the photodegradation of pharmaceutical compound namely diclofenac (DCF) in water. The N,S-CQDs/TiO2 nanocomposites were synthesized with different loadings of N,S-CQDs (1.0 g, 1.5 g and 2.0 g) on TiO2 nanoparticles. Subsequently, the synthesized N,SCQDs/TiO2 nanocomposites were deposited on the PSF membrane via in-situ phase inversion method. The membranes were evaluated for the photodegradation of 10 ppm of DCF under UV light and visible light irradiation. Different characterization techniques including FTIR, XRD, SEM-EDX and sessile drop analysis methods were employed to characterize the membranes. The 1.5 N,S-CQDs/TiO2 membrane exhibited the highest photodegradation performance among the membranes with 62.3% of DCF removal under visible light while the pure TiO2 membrane only showed 3.33% removal. The study showed that 1.5 g loading of N,S-CQDs on TiO2 had successfully shifted and broadening the light absorption wavelength from UV range to visible light range and enhanced the photodegradation performance. In addition, the 1.5 N,S-CQDs/TiO2 membrane showed improved hydrophilicity with the highest permeability of 277 L/m(2).hr.bar. This study demonstrated that N,S-CQDs/TiO2 is a promising photocatalyst for the photocatalytic membrane fabrication.