Solar photocatalytic degradation of methylene blue by mixed metal oxide catalysts derived from ZnAlTi layered double hydroxides

Abstract

ZnAlTi layered double hydroxides (LDHs) with different Zn:Al:Ti ratios were synthesized by homogeneous precipitation method utilizing urea hydrolysis. The synthesized samples were calcined at 873K in order to obtain mixed metal oxides with high photocatalytic activity. Multiple characterizations such as XRD, FT-IR, TG–DSC, XPS, XRF, N2 adsorption–desorption isotherms and UV–vis DRS were carried out. The photocatalytic activity was evaluated by degradation of methylene blue (MB) dye under solar light irradiation. The experimental parameters such as the catalyst with different molar ratios, catalyst dose, initial MB concentration, and initial pH were studied in detail. A maximum of 99% photodegradation of MB was achieved with the catalyst loading of 1.0gL−1 and initial MB concentration of 10mgL−1, at the condition of neutral pH. The kinetic study indicated that the photocatalytic process was well fitted to the Langmuir–Hinshelwood model. Furthermore, after three cycles, the degradation of MB was still close to 90%, indicating that the photocatalyst had high stability for recycle.