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 Zn 2+ /Ni 2+ 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, N 2 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 Zn 2+ /Ni 2+ 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.