Non-metal cocatalyst CNT-modified emerging g-C3N4 for enhanced treatment of waste drilling fluid filtrate†

Loading with non-metal cocatalysts to regulate interfacial charge transfer and separation has become a prominent focus in current research. In this study, g-C₃N₄/CNT composites loaded with non-metallic cocatalysts were prepared through in situ pyrolysis using urea and CNTs. Various characterization techniques, including transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), photoelectrochemical (PEC) analysis, fluorescence lifetime spectroscopy (TRPL), electron paramagnetic resonance spectroscopy (ESR), and photoluminescence (PL) spectroscopy, were employed to analyze the sample's microstructure, phase composition, elemental chemical states, and photoelectronic properties. The photocatalytic performance of the g-C₃N₄/CNT composite in the degradation of actual drilling hydraulic filtrate was evaluated under simulated sunlight irradiation, with the degradation results assessed through COD and chroma measurements. The findings indicate that in g-C₃N₄/CNT composites loaded with non-metal cocatalysts, the photocatalytic performance improves significantly as the CNT content increases. At a CNT mass fraction of 6.0%, the composite achieves optimal performance, with a COD degradation rate of 0.3742 h⁻¹ and a chroma degradation rate of 81%. These results offer valuable insights into enhancing photocatalytic treatment of waste drilling hydraulic filtrate using g-C₃N₄-based non-metallic cocatalysts.