Degradation of Fluoroquinolone-Based Pollutants and Bacterial Inactivation by Visible-Light-Active Aluminum-Doped TiO2 Nanoflakes

Abstract

The development of a visible-light-active photocatalyst for the removal of organic contaminants from water is of primary importance. In this work, we have developed a one-pot synthesis method for visible-light-active aluminum-doped titania (TiO2) with highly efficient sorption degradation of the fluoroquinolone-based pharmaceutical pollutant norfloxacin in aqueous solution. Here, we reduced the effective band gap of TiO2 by in situ doping of aluminum (1 mol %), which significantly improves the porosity, resulting in a high sorption capacity (209 mg/g) toward norfloxacin. The doping of aluminum in TiO2 makes it photocatalytically active in visible light and overcomes the shortcomings of undoped TiO2 in favor of the photodegradation process. 1% aluminum-doped TiO2 (AT) nanoflakes achieves 93% norfloxacin removal (of 2 × 10-4 M) in 2 h with almost 5 times higher rate constants (0.0143 min-1) compared to undoped TiO2 nanoflakes under visible light. Additionally, a high bacterial disinfection activity of doped samples compared to undoped TiO2 in visible light (nearly 80%) as well as in the dark (nearly 20%) was also observed toward both Staphylococcus aureus and Escherichia coli bacteria. The end product of the degradation process was analyzed using mass spectroscopy to determine the mechanistic pathways of the degradation process and the fate of the pollutants. The reusability of the prepared samples was tested and found to be active even after several cycles.