Dual sites design of CoFe/Mg MMO catalyst for effectively suppressing dimethylamine re-emission: Degradation products and DFT calculation

Abstract

Dimethylamine (DMA), a widely used organic solvent and famous malodorous volatile organic compound (VOC), is easily released into the atmosphere and harms human health. Here, we designed a bifunctional CoFe/Mg mixed metal oxide (MMO) catalyst for activating peroxymonosulfate (PMS) to degrade aqueous DMA, thereby inhibiting DMA re-emission. The results indicated that the DMA (100 mg/L) degradation efficiency exceeded 90% within 80 min. Moreover, the re-emission of DMA into the atmospheric environment was reduced by 80% after catalysis. Electron paramagnetic resonance (EPR) measurements and quenching tests verified SO4•− and •OH as the active oxygen species in the CoFe/Mg MMO–PMS system. Combined characterization and density functional theory (DFT) calculation results confirmed that the Co species served as catalytic sites for PMS activation, and the adjacent Mg species acted as adsorption sites for DMA. The synergy effects between the dual sites could accelerate the PMS activation, facilitate the generation of free radicals, and shorten the migration distance between free radicals and pollutants, to realize the efficient DMA degradation. The degradation mechanism and suppressing re-emission process were proposed. This study will provide distinctive insights into the design of catalysts with dual sites and pioneer an unparalleled approach to the industrial governance of effluvial VOCs treatment.