Transformation of bisphenol A by manganese oxide-coated sand

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摘要：

Oxidative transformation of organic contaminants by manganese oxides was commonly investigated with pure MnO2 suspension, which deviates from the fact that natural manganese oxides are seldom present as a pure form in the natural environment. In this study, we prepared manganese oxide-coated sand (MOCS) and evaluated its oxidative capacity using bisphenol A (BPA) as the model compound. BPA was transformed by MOCS and the reaction followed an exponential decay model. The reaction was pH dependent and followed the order of pH 4.5 > pH 5.5 > pH 6.5 > pH 7.5 > pH 8.6 > pH 9.6, indicating that acidic conditions facilitated BPA transformation while basic conditions disfavored the reaction. Coexisting metal ions exhibited inhibitory effects and followed the order of Fe3+ > Zn2+ > Cu2+ > Ca2+ > Mg2+ > Na+. Transformation of BPA by MOCS was much slower than that by pure MnO2 suspension. However, similar transformation products were identified in both studies, suggesting the same reaction pathways. This work suggests that the reactivity of MnO2 in the environment might be overestimated if extrapolating the result from the pure MnO2 suspension because natural MnO2 is mainly present as coating on the surface of soils and sediments.

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关键词：

OXIDATIVE REMOVAL AQUEOUS-SOLUTION DIOXIDE BIRNESSITE SURFACES KINETICS WATER COPPER(II PATHWAYS PRODUCTS