Visible light driven degradation of BPA and LDPE microplastic films using GO/SCN nanocomposite

Abstract

A sonication assisted method was employed to prepare a graphene oxide (GO)/sulfur doped carbon nitride (SCN) nanocomposite, demonstrating enhanced photocatalytic activity compared to GO and SCN. Extensive characterization confirmed the improved properties of the nanocomposite. X-ray Diffraction (XRD) results indicated that the SCN lattice remained intact upon GO addition while Fourier-transform infrared spectroscopy (FTIR) revealed chemical interaction between GO and SCN. X-ray photoelectron spectroscopy (XPS) confirmed sulfur incorporation into the graphitic carbon nitride (g-C₃N₄) lattice. Scanning electron microscopy (SEM) and Transmission Electron Microscopy (TEM) highlighted the distinct morphological features of GO, SCN, and GO/SCN nanocomposites, with SCN showing flat, thin nanosheets and GO displaying flake-like layers, both contributing to a high surface area and mechanical strength. In the GO/SCN nanocomposite, these structures were intermixed, enhancing surface area, mechanical stability, and electron mobility, which contributed to the improved catalytic performance. Ultraviolet-visible diffuse reflectance spectroscopy (UV-DRS) showed a reduction in band gap energy from 2.62 eV for SCN to 2.52 eV for the GO/SCN composite, leading to enhanced visible light absorption. Under visible light irradiation, low density polyethene (LDPE) films experienced significant degradation, evidenced by a 21% weight loss after 10 days, supported by SEM analyses showcasing surface changes on the LDPE films. The degradation was further confirmed by an increase in the carbonyl index (C.I.) from 0.37 to 1.24, measured through FTIR analyses, indicating oxidation corroborating the degradation process. Furthermore, BPA degradation reached 89.5% within 60 minutes under visible light irradiation. Radical trapping experiments confirmed hydroxyl radicals (˙OH) as the active oxygen species involved in the degradation of BPA.