Remove of triclosan from aqueous solutions by nanoflower MnO2: insight into the mechanism of oxidation and adsorption

ABSTRACT

Triclosan (TCS) has been proved to have a harmful effect on human health and ecological environment, especially during the COVID-19 epidemic, when plentiful antibacterial hand sanitizers were discharged. Manganese dioxide (MnO2) showed a good effect on the removal of TCS. The morphology of MnO2 was regulated in this study to increase the active sites for removing TCS and improve the removal effect. The results showed that nanoflower T-MnO2 exhibited best removal efficiency due to its high oxygen vacancy, high Mn3+ content, easily released lattice oxygen and unique tunnel structure which make its Mn-O bond easier to activate. Further study of the mechanism revealed that the process of removing TCS by MnO2 was the first adsorption and then oxidation process and the detailed reaction process was clarified. 3-chlorophenol and 2,4-dichlorophenol were proved to be their oxidative product. Additionally, it was verified that oxidation dominated in the removal of TCS by MnO2 rather than adsorption through Density functional theory (DFT) calculations analysis. It is determined that nanoflower MnO2 was a promising material for removing TCS.