Manganese(III/IV) oxides are strong oxidants found in a wide range of natural environments. Bisphenol A (BPA) is a phenolic compound and an environmental contaminant found at concentrations that are considered harmful for aquatic life. This endocrine disrupting compound is often introduced into natural waters in wastewater treatment plant effluent and landfill leachate. Here we observe the effects of loading rate on the mechanism of BPA oxidation by δ-MnO2 using stirred-flow reactors at pH 5. The total reaction time varies with influent BPA concentration to ensure the same total amount of BPA reacted. 4-Hydroxycumyl alcohol (HCA), a major BPA oxidation product, is detected in the reactor effluent and used to probe the production of organic products by radical coupling. The relative production of HCA changes from 30% to 70% by mole as the initial BPA concentration increases from 20 µM to 160 µM, indicating that the oxidation mechanism changes as the BPA loading rate changes. Additionally, the concentration of aqueous manganese produced relative to BPA decreases with increasing mobile phase concentration. This further proves that the mechanism and products of BPA oxidation by δ-MnO2 change as a function of BPA loading, with higher loading rates favoring the formation of polymeric products. The oxidation mechanism of BPA and other phenolic contaminants is important to water treatment and groundwater quality and remediation.

Changes in bisphenol A oxidation mechanism in the presence of manganese oxide

255th National Meeting (2018)

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