Manganese-Doped Ceria as a Dual-Functional Nanomaterial in the Treatment of Gaseous Pollutants and Antibacterial

Abstract

This study discovered excellent properties for the structures, morphologies and catalytic oxidation of gaseous pollutants as well as antibacterial activity of Mn-doped ceria nanocomposites (MnO_x–CeO₂). The MnO_x–CeO₂ samples were synthesized by the impregnation route, based on ceria nanorods pre-formed by the hydrothermal method. The doping of CeO₂ nanorods with MnO_x led to a decrease in the crystal size of CeO₂ and an increase in the reduction capacity of the catalyst at low temperatures. The catalytic activity of as-prepared MnO_x–CeO₂ was investigated in the deep oxidation of p-xylene and CO at low temperatures (100–300°C). The results exhibited that the catalytic activity of CeO₂–MnO_x composite oxides was higher than that of the pure CeO₂ nanorod. The 7.5MnCe composite was the most efficient for p-xylene oxidation, reaching complete p-xylene conversion at 300°C. Besides, the activity of 7.5MnCe sample in oxidation of single CO or p-xylene or CO + p-xylene mixture was also comparatively investigated. For CO oxidation, the CO conversion in the mixture is lower than that of single CO due to competitive adsorption with p-xylene. In contrast, for the p-xylene oxidation, its conversion in the mixture was higher than that of single p-xylene, caused by the heat promotion from the CO oxidation. The antibacterial effect of the 7.5MnCe sample was evaluated by implementing the minimum inhibitory concentration test (MIC) against P. aeruginosa, Salmonella, E. coli, S. aureus, and B. cereus. The 7.5MnCe sample presented effective antibacterial activity against all bacteria with a lower MIC of 2.5 mg/mL.

Fig. 5 The catalytic activities of 7.5MnCe nanomaterial for p-xylene and/or CO oxidation; the oxidation of single CO or p-xylene (S) and the oxidation of CO + p-xylene mixture (M).