Ordered Mesoporous Cobalt Containing Perovskite as a High-Performance Heterogeneous Catalyst in Activation of Peroxymonosulfate

An ordered mesoporous perovskite, La2CoMnO6-δ (MLCMO), was synthesized for the first time using a facile method of evaporation-induced self-assembly. The N2-sorption, scanning electron microscopy, and transmission electron microscopy measurements indicated that the optimized MLCMO possessed a high specific surface area (58.7 m2/g) and was uniformly mesoporous (11.6 nm). The MLCMO exhibited superior catalytic performance in peroxymonosulfate (PMS) activation for atrazine (ATZ) degradation. From a comparison view, the catalytic activity of the mesoporous MLCMO outperformed that of the bulk La2CoMnO6-δ (LCMO) and other common PMS activators, including α-MnO2, Co3O4, and CoFe2O4. The mechanisms of PMS activation by the MLCMO were investigated by X-ray photoelectron spectroscopy, electron spin resonance, and quenching tests. SO4•-, •OH, 1O2, and O2•- were identified as main reactive oxygen species generated from PMS activation. The Co and Mn in MLCMO were the active sites responsible for active radical generation. The lattice oxygen reversible redox sites (OL-/OL2-), which were involved in the electron transfer of the MnIII/MnIV cycle, were demonstrated as redox partners to the cation active sites. In addition, the SO4•-/•OH radical conversion was promoted at pH 11, which accelerated the consumption of PMS and seriously inhibited the degradation of ATZ.