Removal of acetaminophen through direct electron transfer by reactive Mn2O3: Efficiency, mechanism and pathway

Abstract

Mn2O3 with certain oxidative reactivity, was fabricated via sol-gel method and applied for the removal of acetaminophen (APAP). The mechanism of APAP oxidation was revealed in depth through electrochemical tests and X-ray photoelectron spectroscopy (XPS). Moreover, the selective abatement of various organic contaminants contained different functional groups by Mn2O3 was investigated through linear free energy relationship (LFER) estimated with peak potentials (Eop) of these organic contaminants. Under acidic condition, APAP could be effectively eliminated by Mn2O3. The open circuit potential (OCP) and zeta potential tests illustrate that the oxidative reactivity of Mn2O3 is associated to the surface acid-base behavior of Mn2O3 and its surface charge situation. The XPS experiments and Mn leaching results imply that Mn(III) could capture electron from APAP and release Mn2+ to aqueous phase. The intermediates could be ascribed to fragmentation of acetamido radicals and phenoxy radicals, both of which were formed through electron transfer from APAP to Mn2O3. The reactive Mn2O3 shows selective oxidation of different contaminants in the electron transfer process. LFER analysis indicates good negative linear correlation between lnk1 and Eop of various pollutants. The efficiency of Mn2O3 in the elimination of APAP and selective oxidation of different contaminants suggest some new insights for transformation of APAP and other electron-rich pollutants in the environments.