Enhanced catalytic activity of templated-double perovskite with 3D network structure for salicylic acid degradation under microwave irradiation: Insight into the catalytic mechanism

Abstract

Salicylic acid (SA) is considered as a priority pollutant due to its physiological toxicity and pseudo-persistence in the environment. In this study, a new catalytic degradation technology using microwave (MW) induced templated-double perovskite was proposed and applied in the treatment of SA in aqueous solution. A series of LaCo1-xCuxO3@PMMA (X = 0, 0.3, 0.5, 0.7, 1) perovskite-type catalysts with three-dimensionally porous network structure were synthesized by polymethylmethacrylate (PMMA) templating method, and characterized by scanning electron microscopy (SEM), N2 adsorption-desorption analysis (BET), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and microwave network analysis. The results showed that the addition of PMMA template and substitution with Cu (x = 0.5) were beneficial to the generation of LaCo0.5Cu0.5O3@PMMA with high catalytic activity, which possessed unique 3D porous network structure, smaller particle size distribution, better microwave absorbing performance and higher ratios of Co3+/Co2+ and Oads/Olatt. The SA removal fit pseudo-first-order model, and its degradation efficiency increased firstly and then decreased with the increase of MW intensity, solution pH and catalyst dosage, while decreased as initial SA concentration increasing. The LaCo0.5Cu0.5O3@PMMA catalyst presented favorable recycling and stability in the repeated experiment. The excellent catalytic activity was attributed to both active species and MW “hot spots”, among which OH and hvb+ played main roles in the catalytic process, and MW “hot spots” effect had a small contribution to the degradation. Hence, LaCo0.5Cu0.5O3@PMMA/MW technology with rapid degradation and negligible secondary pollution provides a potential way for treating salicylic acid in water.