Ultrasonic degradation of bisphenol A, 17β-estradiol, and 17α-ethinyl estradiol in aqueous solution

This study examined the relative degradation of commonly known endocrine-disrupting compounds (EDCs) such as bisphenol A (BPA), 17β-estradiol (E2), and 17α-ethinyl estradiol (EE2) in single-component aqueous solution using 28, 580, and 1,000 kHz ultrasonic reactors. The degradation of EDCs follows a pseudo-first order rate kinetics; the order of degradation is EE2 ≥ BPA > E2. At different frequencies, the degradation of these compounds follows the order 580 kHz (92-97%) > 1,000 kHz (90-94%) > 28 kHz (62-67%) at an initial concentration of 1 mM of each compound with a contact time of 30 min. Additional experiments were performed to determine the effects of carbon tetrachloride (CCl₄, H• scavenger) and tert-butyl alcohol (t-BuOH, HO• scavenger) on BPA, E2, and EE2 degradation at 580 kHz with a reaction time of 30min. The addition of t-BuOH slightly decreased the rate of BPA degradation as follows: no addition (97%), 0.01 mM (96%), and 0.1 mM (95%). At high t-BuOH concentrations of 1, 10, and 100 mM, the degree of degradation was significantly decreased; that is, the degradation decreased to 90%, 33%, and 20%, respectively. However, in the presence of CCl₄, the BPA degradation increased as follows: no addition (97%), 0.01/0.1 mM (98%), 1 mM (99.7%), and 10 mM (99.8%).