g-C3N4-promoted degradation of ofloxacin antibiotic in natural waters under simulated sunlight
2017
Sturini, Michela | Speltini, Andrea | Maraschi, Federica | Vinci, Giulia | Profumo, Antonella | Pretali, Luca | Albini, Angelo | Malavasi, Lorenzo
This is the first report on the photodegradation of ofloxacin under simulated solar light and in actual environmental matrices in the presence of a g-C₃N₄ suspension. The catalyst, prepared from the polymerization of dicyandiamide (650 °C, reaction yield 60%), was characterized by means of powder X-ray diffraction (PXRD), UV-vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), and BET surface area measurements. The experiments were carried out in a lab-scale batch reactor at concentrations in the range of micrograms/milligrams per liter. The course of the reaction was monitored by high-pressure liquid chromatography with UV-vis and fluorescence detectors. The g-C₃N₄-promoted photodegradation occurred at a rate 10 times faster than the direct photolysis and obeyed a first-order kinetics; in addition, the photodegradation kinetics of sonicated g-C₃N₄ resulted to be of the same order of that caused by P25 TiO₂. Finally, the photochemical paths and the photoproducts have been identified and compared to those obtained by using P25 TiO₂. From the results of this study, it can be concluded that g-C₃N₄ is a very attractive photocatalyst compared to P25 TiO₂ in view of its ease of preparation, low cost, excellent oxidizing properties, large fraction of solar radiation absorbed, and intrinsically layered structure.
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