Mechanism and Degradation Pathways of Bisphenol A in Aqueous Solution by Strong Ionization Discharge

Bisphenol A (BPA) can potentially trigger hormonal imbalances and affect aquatic species when discharged untreated into the ecosystems. This study explored the influencing factors, mechanism, and pathways of BPA degradation process in aqueous solution applying strong ionization discharge (SID) method. The results elaborate that 99.5% degradation rate was achieved in 60 min when 15 mg L−1 BPA solution was treated applying 3.74 kW of input power. Weak alkaline conditions were favorable to BPA removal in SID system. In addition, the inhibition of radical scavengers on the SID process laterally verified the presence of hydroxyl radicals (HO·) in the oxidation process besides ozone (O3). What is more, the addition of 15 mg L−1 sodium percarbonate (SPC) can improve 6.93% degradation rate of 30 mg L−1 BPA based on the SID system. Furthermore, ultraviolet-visible spectroscopy (UV-vis), high-performance liquid chromatography (HPLC), total organic carbon (TOC), and chemical oxygen demand (COD) analysis were conducted to measure the capacity of SID system for BPA treatment. The molecular analysis via liquid chromatography-mass spectrometer (LC-MS) and gas chromatography-mass spectrometer (GC-MS) showed that a portion of the intermediates in BPA degradation process were characterized by 3,4-dihydroxybenzoic acid, o-xylene, p-xylene, and propane-1,2,3-triol, etc., which were ultimately mineralized into CO2 and H2O. Based on the above analysis, the SID oxidation mechanism and pathways were proposed.