Phenol driven changes onto MnO2 surface for efficient removal of methyl parathion: The role of adsorption

Manganese oxides (MnO 2 ), important environmental oxides, have drawn significant attention in areas such as detoxification of micro-hazardous organic contaminants with electron-donating functional groups such as –OH. However, studies on whether these oxidized processes might further impact the fate of some esters like organophosphorus pesticide (OPPs) remain poorly understood. Herein, we propose a new mechanism involved in the enhanced removal of methyl parathion in mixtures of MnO 2 and phenol. Specifically, the removal of methyl parathion (up to 73.7%) was significantly higher for a binary system than for MnO 2 alone (approximately 9.3%) and was primarily due to adsorption rather than degradation. The extent of methyl parathion adsorption was dependent significantly on pH, reactant loading and metal ion co-solutes (such as Ca 2+ , Mg 2+ , Fe 3+ and Mn 2+ ). Both spectroscopic (FT-IR, SEM-EDX and XPS) and chromatographic (LC/HRMS) analyses showed that the remarkable increase in the number of organics (e.g., polymers) onto the MnO 2 surface dominated methyl parathion adsorption via hydrogen bonding, n-π and π-π interactions, van der Waals forces and pore-diffusion. The results from this study provided evidence for the role of manganese oxides in adsorption of methyl parathion in soil-aquatic environments involving phenolic compounds .