Investigation of the effect of magnesium and activated carbon on the photocatalytic degradation reaction of ZnO photocatalyst

To improve the photodegradation of methyl blue (MB) by ZnO under visible light irradiation, the sol–gel method was used to synthesize ZnO photocatalysts co-doped with Mg and supported on activated carbon (AC) with various properties. The photocatalysts synthesized were characterized in terms of their structure and optical properties. X-ray diffraction and UV-vis absorption spectra measurements were carried out to examine the structural and optical properties of photocatalysts. Such photocatalytic behaviors of photocatalysts preceded the order: Mg:ZnO/AC > ZnO/AC > ZnO. This consequence was ascribed to the small crystallite size, large surface area, the narrow bandgap of Mg:ZnO/AC photocatalyst. Besides, first-order kinetics accompanied the degradation of MB on photocatalysis. The active species •OH and •O2– performed more key roles in composite photocatalytic degradation of MB.