ZnS/ZnNiAl-LDH/GO nanocomposite as a visible-light photocatalyst: preparation, characterization and modeling

In the present research, in order to enhance the photocatalytic activity of ZnS, the ZnS/ZnNiAl-LDH/GO nanocomposite was synthesized via co-precipitation method. The obtained solid was characterized by UV–vis diffuse reflectance spectra (DRS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The photocatalytic performance of the synthesized nanocomposite was investigated via photodegradation of Reactive Red 43 as a model organic pollutant. The removal efficiency of dye over ZnS/ZnNiAl-LDH/GO nanocomposite was compared with blank ZnS, ZnNiAl-LDH and ZnNiAl-LDH/GO. Under the experimental conditions the maximum removal was yielded when ZnS/ZnNiAl-LDH/GO nanocomposite was used (86%). The DRS results revealed that after incorporating GO and ZnNiAl-LDH the visible light absorption of the as-prepared nanocomposite greatly enhanced there was a wide band in the visible light region with a large absorption tail. The response surface methodology (RSM) was used to investigate the effect of different operational parameters including pH, nanocomposite dosage and time, on the dye photodegradation efficiency. The possible mechanism for photodegradation of the dye was also studied using appropriate scavengers for active species like O ₂ ^•− , h⁺ and OH^•, and demonstrated that the superoxide radicals were the main oxidative spices in this photocatalytic system.