Microwave catalytic activities of supported perovskite catalysts MOx/LaCo0.5Cu0.5O3@CM (M = Mg, Al) for salicylic acid degradation

Abstract

Three-dimensionally (3D) meso-macroporous LaCo0.5Cu0.5O3@CM and MOx/LaCo0.5Cu0.5O3@CM (M = Mg, Al) perovskites were synthesized by impregnation of carbon microsphere (CM) templates and calcination method. The obtained perovskites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and microwave network analysis. The composite catalysts were prepared for the microwave (MW)-induced H2O2 catalytic degradation of salicylic acid (SA) as a target contaminant in aqueous solution. Results showed that Al2O3/LaCo0.5Cu0.5O3@CM displayed higher microwave catalytic activity than MgO/LaCo0.5Cu0.5O3@CM, which was closely related to its higher active species concentration, better microwave absorbing ability and the interaction between Al2O3 and LaCo0.5Cu0.5O3@CM. Moreover, the degradation kinetics could be well fitted by the pseudo first-order kinetic model. As the increase of MW power, initial pH, dosage of catalyst and H2O2 concentration, its SA degradation rate first increased and then decreased, while the initial SA concentration declined continuously. The introduction of metal oxides increases the mobility of the surface oxygen, playing a crucial role in surface oxygen species generation. The enhancement of catalytic activity could be mainly ascribed to the OH activation process under MW irradiation. After five reaction cycles, the stability and reusability remained high. The overall findings provide new insight into Al2O3/LaCo0.5Cu0.5O3@CM under MW irradiation for the degradation of SA and other relevant organic pollutants.