Enhanced Degradation of Bisphenol A via Ultrasound, Assisted by Chemical Treatment

Abstract

Ultrasonic technology (US) can be considered a very sustainable and efficient method to remove bisphenol A (BPA) from water. Compared with other methods, the proposed method has some advantages: a simple implementation on existing water treatment and purification facilities, it does not generate residual compounds that produce sludge, a relatively fast time is required for degradation (1–2 h), and high degradation efficiencies. In this work, we present the results regarding BPA degradation efficiency using the ultrasonic technique. The influence of frequency and of some additional compounds, such as carbon tetrachloride (CCl4), FeSO4 7H2O (FS), and ethyl anthraquinone (EAC), were studied. Three different frequencies were used: 1146 kHz, 864 kHz, and 580 kHz, at 50 W. The sampling, performed every 15 min, revealed that the highest BPA degradation was achieved after 60 min. Using the liquid chromatography tandem mass spectrometry (LC-MS/MS) technique, the degradation compounds were identified. Pathways of BPA degradation were also proposed. The use of additives such as CCl4, FS, and EAC proved to have a positive effect on the BPA degradation process assisted by ultrasound. After 60 min of exposure, the degradation capacities reached values of between 50% and 75%, while the mineralization capacities were situated between 20% and 35%. CCl4 and EAC had a more pronounced stimulating action than FS, with the EAC having the highest mineralization capacity, representing around 75% of the degradation capacity.