Rapid photocatalytic degradation of acetaminophen and levofloxacin using g-C₃N₄ nanosheets under solar light irradiation

Rapid photocatalytic performance was targeted through modifying the graphite-like carbon nitride (g-C₃N₄) bulk materials to nanosheet structure via thermal oxidation etching process. Simple thermal oxidation etching treatment was used in order to reduce multilayer g-C₃N₄ structure to nanosheet material. The differences in the obtained sample of g-C₃N₄ nanosheets and pristine g-C₃N₄ were characterised via scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), Photoluminescence (PL), Fourier-transform infrared spectroscopy (FTIR), UV–vis diffuse reflectance spectroscopy (UV–vis DRS), Brunauer–Emmett–Teller (BET) analysis and particle size analysis. The photocatalytic efficiency was tested for the degradation of acetaminophen and levofloxacin under direct solar irradiation. The results showed some variation in XRD, particle size and BET results indicating that etching process was evolved in reducing the particles size and lowering the layers number in g-C₃N₄ bulk sample. The optical and band gap properties results noticed some variation where the XPS and FTIR spectra showed some modification on g-C₃N₄ nanosheet motif such as the C–H, CO and N pyridinic structure. Accordingly, the photocatalytic degradation of acetaminophen by the g-C₃N₄ nanosheets under solar irradiation was much faster and reached 99% in one hour where in the case of g-C₃N₄ bulk sample the degradation reached only 38% in 4 h. Similarly, levofloxacin degradation with nanosheet sample reached 99% in one hour compare to 16% in presence of the bulk sample. This enhancement can be attributed to multiple factors such as smaller particle size, rich carbon surface and lower band gap exhibited by the g-C₃N₄ nanosheets. This further indicates that the performance of g-C₃N₄ can be further enhanced via this method and can used to treat wastewater contaminated by pharmaceuticals under solar irradiation. (paper)