Comparison of effects of multiple oxidants with an ultrasonic system under unified system conditions for bisphenol A degradation. (July 2023) - Sun, Shiyu
Abstract: Bisphenol A (BPA) as a trace contaminant has been reported, due to widespread use in the plastics industry. This study applied the 35 kHz ultrasound (US) to activate four different common oxidants (H2 O2, HSO5 −, S2 O8 2−, and IO4 − ) for BPA degradation. With increasing initial concentration of oxidants, the degradation rate of BPA increased. The synergy index confirmed that a synergistic relationship between US and oxidants. This study also examined the impact of pH and temperature. The results showed that the kinetic constants of US, US-H2 O2, US-HSO5 - and US-IO4 − decreased when the pH increased from 6 to 11. The optimal pH for US-S2 O8 2− was 8. Notably, increasing temperature decreased the performance of US, US-H2 O2, and US-IO4 - systems, while it could increase the degradation of BPA in US-S2 O8 2− and US-HSO5 - . The activation energy for BPA decomposition using the US-IO4 - system was the lowest, at 0.453nullkJnullmol −1, and the synergy index was the highest at 2.22. Additionally, the ΔG# value was found to be 2.11 + 0.29T when the temperature ranged from 25 °C to 45 °C. The main oxidation contribution is achieved by hydroxyl radicals in scavenger test. The mechanism of activation of US-oxidant is heat and electron transfer. In the case of the US-IO4 - system, the economic analysis yielded 271 kwh m −3, which was approximately 2.4 times lower than that of the US process. Graphical abstract: Image 1 Highlights: US-IO4 - system showed excellent degradation capacity of BPA in a low-frequency (35 kHz) US. Visual verification of the activation process by sono-chemiluminescence. The SI for BPA degradation using the US-IO4 system was the highest at 2.22. Hydroxyl radicals are the main contributors to the oxidation process. The energy consumption of the US-IO4 - was 271 kwh m −3, 2.4 times lower than that of the US.