Investigation of Interfacial Interaction of Manganese Oxides with Organic Micropollutants

Abstract

Water reuse has become a necessary practice in arid and semi-arid regions like the Southwestern USA. However, a new generation of emerging organic micropollutants has been increasingly scrutinized in water sources. The aim of this study is to determine the changes in chemical composition occurring on the MnOx(s) surface after reaction with organic micropollutants using X-ray Photoelectron spectroscopy (XPS), Raman spectroscopy and solution chemistry analyses. Laboratory batch experiments were conducted to assess the reactivity of MnOx(s) with aniline, triclosan, phenol and bisphenol A. Analyses of XPS high resolution scans through the determination of the shape and position of Mn 3p spectra and Mn 3s multiplet splitting suggest that Mn(III) and Mn(II) increase in the surface of MnOx(s) reacted with organics, indicating that organic oxidation causes the reduction of MnOx(s). Impurities on MnOx(s) surface (eg. other metal oxides) decrease the micropollutant removal efficiency. After the rapid initial oxidation of micropollutants, the availability of surface sites was found to be a major factor influencing the long-term reaction rates. Aniline and Bisphenol A were still detectable after reaction completion due to surface sites being irreversibly occupied by reaction products or impurities. The results from this research are applicable for the mechanistic comprehension of interactions between MnOx(s) and organic micropollutants, which is necessary for understanding the MnOx(s)-micropollutant geochemical processes and development of water treatment technologies that use MnOx(s) to remove organic micropollutants.Civil EngineeringMastersUniversity of New Mexico. Dept. of Civil EngineeringCerrato, JoseAli, Abdul-MehdiHowe, Kerr