Sonophotocatalytic Degradation of Endocrine Disrupting Chemical 4-cumylphenol in the Presence of Inorganic Oxidant Species in Aqueous Solution

The sonophotocatalytic (US/UV/TiO₂) degradation of endocrine disrupting compound 4-cumylphenol (4-CP) at low ultrasound frequency in aqueous solution was investigated. A more remarkable synergistic effect was observed on the 4-CP degradation by US/UV/TiO₂ process, at low ultrasound frequency reactor equipped with a focalization system, than that observed in the case of individual process such as sonolytic (US), photolytic (UV), and photocatalytic (UV/TiO₂). The influence of the operating parameters such as 4-CP initial concentration, ultrasound power and frequency, nano-catalyst concentration, pH and saturating gas on the degradation process was examined. In addition, to assess the potential reaction sites of hydroxyl radical-mediated oxidation of 4-CP, we monitored its degradation in the presence of tert-butyl-alcohol scavengers of OH radicals in the liquid–solid interface. The presence of persulfate ions is able to enhance the degradation efficiency of 4-CP, because its presence enhances the production of more OH radicals quantities. The 4-CP degradation rate was frequency dependent. This rate increased proportionally with the increasing power from 10 for 50 W. The most favorable degradation pH was the acidic media. The degree of 4-CP decay was fast in the presence of argon and slowed down as the gas was replaced by air or nitrogen. At low ultrasound frequency, the results indicated that total chemical oxygen demand (COD) removal was obtained in the tested 4-CP solutions when applying (US/UV/TiO₂/S₂O₈⁻²) system.