Bisphenol A (BPA) is an endocrine-disrupting compound (EDC) that is mainly released from anthropogenic sources. In this study, the degradation mechanism of BPA during vacuum ultraviolet (VUV) reaction was investigated. The degradation of BPA during VUV reaction followed the pseudo-first-order reaction kinetics. Within 60 min reaction at pH 7.0 and temperature controlled at 20.0 ± 2.0 °C, 99.5% removal of BPA was achieved with the degradation rate constant (kobs) of 6.71×10-2 min-1 (R2 = 0.99) for VUV reaction. On the other hand, only 15% of BPA removal was achieved during UV-C exposure at the same condition. As the pH increased from 6.0 to 9.0, the BPA degradation rate decreased from 8.67×10-2 to 5.08×10-2 min-1 which implies VUV is an efficient method over UV-C. Moreover, the presence of dissolved organic matter (DOM) and inorganic ions was investigated, where DOM and NO3- inhibited the degradation of BPA during VUV reaction. More than 91% of total organic carbon (TOC) in BPA was mineralized within 12 hr of the VUV/UV reaction. Seven organic transformation products (TPs) of BPA were identified using LC-qTOF/MS, and the BPA degradation pathways in the VUV process were proposed based on identified TPs. Finally, 34% decrease in bioluminescence inhibition in Vibrio fischeri was observed during the VUV reaction, implying that VUV process is a promising treatment for mineralization and toxicity reduction of BPA.

Degradation kinetics and mechanism of bisphenol A in vacuum ultraviolet photolysis

ACS Fall 2021

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