Bisphenol A mineralization by integrated ultrasound-UV-iron (II) treatment.
Bisphenol A (BPA), an organic compound largely used in the plastic industry as a monomer for production of epoxy resins and polycarbonate, is an emerging contaminant that is released in the environmentfrom bottles and packaging. BPA degradation (118 micromol L(-1)) under sonochemical conditions was investigated in this study, using a 300 kHz frequency, with a 80 W electrical power. Under these conditions, BPA was eliminated by the ultrasound process (-90 min). However, even after long ultrasound irradiation periods (10 h), more than 50% of chemical oxygen demand (COD) and 80% of total organic carbon (TOC) remained in the solution, indicating that most BPA intermediates are recalcitrant toward ultrasonic action. Accumulation of hydrogen peroxide from *OH and *OOH radical recombination was also observed. To increase the efficiency of BPA treatment, experiments combined ultrasound with Fe2+ (100 micromol L(-1)) and/or UV radiation (254 nm): Ultrasound/UV; Ultrasound/Fe2+; Ultrasound/UV/ Fe2+. Both UV and Fe2+ induced hydrogen peroxide dissociation, leading to additional *OH radicals and complete COD and TOC removal. Thus difficulties in obtaining mineralization of micropollutants like BPA through ultrasonic action alone, can be overcome by the Ultrasound/UV/ Fe2+ combination. Moreover, this technique was found to be the most cost-effective one. So, the integrated ultrasound-UV-iron(ll) process was shown to be of interest for the treatment of wastewaters contaminated with BPA.