NiZnAl layered double hydroxides as photocatalyst under solar radiation for photocatalytic degradation of orange G

In this paper, well-crystallized NiZnAl layered double hydroxides (NiZnAl-LDHs) at different Zn2+/Ni2+ molar ratio (from 2 to 4) were prepared using dynamic urea hydrolysis method and further calcined at 873 K to obtain the layered NiZnAl mixed metal oxides with high photocatalytic activity. The as-synthesized catalysts were characterized by multiple techniques including XRD, FT-IR, TG-DSC, XPS, XRF, N2 adsorption-desorption isotherms, UV-vis DRS, and SEM. Additionally, their photocatalytic properties were evaluated by degrading orange G (OG) under solar radiation, with the investigation of isothermal adsorption behavior of OG on NiZnAl-LDHs before. Several factors influencing the photocatalytic activity like Zn2+/Ni2+ molar ratio of the catalyst, catalyst dosage, initial dye concentration, and initial pH, have been studied and optimized as 3, 0.5 g L−1, 50 mg L−1 and neutral, respectively, with a maximum of 99% degradation of OG achieved within 100 min reaction. Furthermore, the kinetic study suggested that the photodecomposition process was well fitted to the Langmuir-Hinshelwood model and the mineralization of OG was confirmed by the FT-IR analysis of the catalyst after the degradation. Finally, a probable mechanism was proposed to explain the process of photocatalytic reaction.