Abstract
This paper explores the degradation of a model pollutant, bisphenol A, by an advanced oxidation process that combines sonolysis, Fe2+, and TiO2 in a photoassisted process. Experiments were done under saturated oxygen conditions. The effect of different Fe2+ (0.56 and 5.6 mg/L) and TiO2 (10 and 50 mg/L) concentrations was investigated on both the elimination and mineralization of the pollutant. A pronounced synergistic effect that led to the complete and rapid elimination of dissolved organic carbon (DOC) was observed even at low catalyst loadings. In this system, almost a complete removal of DOC (93%) was observed after 4 h using 10 and 5.6 mg/L of TiO2 and Fe2+, respectively, whereas at the same time, only 5, 6, and 22% of DOC was removed by an individual process alone (TiO2 photocatalysis, ultrasound, and photo-Fenton, respectively). In this system, ultrasound has the principal role of eliminating the initial substrate and providing hydrogen peroxide for the photocatalytic systems, while photo-Fenton and TiO2 photocatalysis are mainly responsible for the transformation of the intermediates in CO2 and H2O. The role of H2O2 generated from the sonochemical process is also discussed. (C) 2010 Elsevier Ltd. All rights reserved.