Carbon-tunable p-type ZnO nanoparticles for enhanced photocatalytic removal of Eriochrome Black T

Photocatalysis with ZnO is a promising alternative to TiO2 photocatalysis especially for the removal of various organic dye pollutants. Methods: Highly crystalline, nanoscopic carbon-doped ZnO was successfully synthesized via a combined precipitation and mechanochemical approach and characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy and Fourier transform infrared (FTIR) analysis. The obtained photocatalysts depicts plate-like morphology and hexagonal wurtzite structure. The XRD, SEM, and FTIR analysis were in good agreement with EDX results. The 5wt % C-doped ZnO showed remarkable visible light-photocatalytic activity for the degradation of Eriochrome Black T (EBT) and exhibits a more favourable point of zero charge (pzc) for adsorption equilibrium. This degradative process was optimized at 97 % using response surface methodology (RSM) with a 0.1 g the C-ZnO and 5.00 mg/L EBT at pH 11. The kinetic data fits the pseudo-first order kinetics model. The resulting C-ZnO was a p-type with a good pH at zero point charge that permits the removal of EBT by C-doped under visible light irradiation over a very wide range of initial pH.