Identification of 4-Hydroxycumyl Alcohol As the Major MnO2-Mediated Bisphenol A Transformation Product and Evaluation of Its Environmental Fate

Bisphenol A (BPA), an environmental contaminant With weak estrogenic activity, resists microbial degradation under anoxic conditions but is susceptible to abiotic transformation by manganese dioxide (MnO2). BPA degradation followed pseudo-first-order kinetics with a rate Constant of 0.96 (+/- 0.03) min(-1) in the presence of 2 mM MnO2 (0.017% w/w) at pH 7.2. 4-hydroxycumyl alcohol (HCA) was the major transformation product, and, on a molar basis, up to 64% of the initial amount of BPA was recovered as HCA. MnO2 was also reactive toward RCA, albeit at 5-fold lower rates, and CO2 evolution (i.e., mineralization) Occurred. In microcosms established with freshwater sediment, HCA was rapidly biodegraded under oxic, but not anoxic conditions. With a measured octanol-Water partition coefficient (Log K-ow) of 0.76 and an aqueous solubility of 2.65 g L-1 HCA is more mobile in saturated media than BPA (Log K-ow = 2.76; aqueous solubility = 0.31 g L-1), and therefore more likely to encounter oxic zones and undergo aerobic biodegradation. These findings corroborate that BPA is not inert under anoxic conditions and Suggest that MnO2-mediated coupled abiotic-biotic processes may be relevant for controlling the fate and longevity of BPA in sediments and aquifers.