Sequential helio-photo-Fenton and sonication processes for the treatment of bisphenol A

This paper demonstrates the coupling of ultrasound (300 kHz, 80 W) with Fe(II) to degrade the contaminant bisphenol A by a solar photo-assisted process carried out at natural pH ∼ 5. An experimental design that allowed runs in batch (ultrasound → Fe2+/UV and Fe2+/UV → ultrasound) or in simultaneous (ultrasound/Fe2+/UV) modes was developed. To gain a better understanding of the phenomena involved in the systems, ultrasound, ultrasound/Fe2+, Fe2+/UV, and Fe2+/UV/H2O2 (photo-Fenton) were also performed. After 4 h of treatment, 11%, 29%, and 70% of the initial total organic carbon had been removed by ultrasound, photo-Fenton, and ultrasound/Fe2+/UV, respectively. The synergistic effect can be explained by the complementarity of the two processes: ultrasound more effectively destroys the initial bisphenol A compound, whereas the photo-Fenton system is better able to eliminate the bisphenol A by-products. The influence of the type of saturating gas (oxygen or air) used was also investigated.