Graphitic Carbon Nitride from Burial to Re-emergence on Polyethylene Terephthalate Nanofibers as an Easily Recycled Photocatalyst for Degrading Antibiotics under Solar Irradiation

For powder catalysts to be recycled easily and to be applied in practical wastewater treatment, it is imperative to search suitable carriers that can be applied to support catalytic particles. Herein, we highlight a facile route to synthesize an easily recycled photocatalyst using polyethylene terephthalate (PET) to disperse graphitic carbon nitride (g-C3N4) via electrospinning and subsequent hydrothermal treatment. The resultant nanofiber is labeled T-g-C3N4/PET. The design concept is to expose the g-C3N4 on the PET surface and convert it from inactivation to re-emergence. g-C3N4 is embedded into the PET, which avoids the reunion and unrecyclable deficiencies of powder catalysts. T-g-C3N4/PET was characterized by field-emission scanning electronic microscopy, transmission electron microscopy, UV vis diffuse reflectance spectra, two-dimensional X-ray diffraction, Fourier-transform infrared spectroscopy, and thermogravimetric analysis technologies. T-g-C3N4/PET showed a high photocatalytic activity for the degradation of antibiotics such as sulfaquinoxaline and sulfadiazine under solar irradiation, and the activity was almost unaffected in a high background. The as-obtained catalysts could be reused several times with no loss in performance in cycling photodegradation tests. Finally, a possible pathway and mechanism for degrading sulfaquinoxaline with T-g-C3N4/PET was proposed, respectively, in which holes and the superoxide radical were the predominant active species, and resulted in the oxidative degradation of antibiotics. These results demonstrate that the preparation method may provide a novel idea for supporting nanoscale catalysts for reuse.