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

• Nanoflower ε-MnO 2 showed the excellent TCS removal efficiency. • Lattice oxygen participated in the reaction of removing TCS by MnO 2 . • Oxidation dominated in the removal of TCS by MnO 2 rather than adsorption. • 3-chlorophenol and 2,4-dichlorophenol were proved to be the oxidative product. • The mechanism and the process of removing TCS by MnO 2 were revealed. 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 (MnO 2 ) showed a good effect on the removal of TCS. The morphology of MnO 2 was regulated in this study to increase the active sites for removing TCS and improve the removal effect. The results showed that nanoflower ε-MnO 2 exhibited best removal efficiency due to its high oxygen vacancy, high Mn 3+ 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 MnO 2 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 MnO 2 rather than adsorption through Density functional theory (DFT) calculations analysis. It is determined that nanoflower MnO 2 was a promising material for removing TCS.