Composition-engineered LaCoO3-based monolithic catalysts for easily operational and robust peroxymonosulfate activation

Abstract

Herein, we report for the first time the construction of perovskite oxide catalysts on monolithic supports for peroxymonosulfate (PMS) activation to eliminate organic pollutants in wastewater. Specifically, the commercially available porous alumina ceramic (PAC) was utilized as monolithic support, on which Ca − Ti co-modified LaCoO3 perovskites (L1−xCxC1−yTyO3) were successfully loaded through a simple, controllable, and reagent-saving “dripping − calcination” process. The resulting monolithic catalysts (L1−xCxC1−yTyO3@PAC) featured large sizes (cm-scale), highly open porous architectures, and compositionally favorable active components, by which easy catalyst recycling, rapid mass transfer of guest species, and high yet stable catalytic performance were harvested in PMS activation for degradation of the typical antibiotic pollutant metronidazole (MNZ). By optimizing the introduction amount of Ca and Ti, the resulting L0.8C0.2C0.4T0.6O3@PAC showed a high turnover frequency (TOF) value of 12.6 min−1 for MNZ with a low cobalt leaching amount of 0.203 mg L−1, which were significantly superior to the unmodified catalyst LCO3@PAC (TOF: 7.9 min−1; cobalt leaching: 1.71 mg L−1). Roles of Ca and Ti modifiers in the LaCoO3-based monolithic catalyst, degradation pathway of MNZ, and SO4−•/1O2 dominated catalytic mechanism were investigated and elucidated. Our work provides a promising avenue for rational design of low-cost, easily operational, and robust monolithic catalysts toward PMS activation for large-scale environmental remediation.