Sonochemical degradation of 2,3,7,8-tetrachlorodibenzo-p-dioxins in aqueous solution with Fe(III)/UV system

Abstract 2,3,7,8-Tetrachlorodibenzo- p -dioxin (2,3,7,8-TeCDD) was rapidly decreased by sonication in aqueous solution. The degradation efficiency was strongly influenced by ultrasonic power and reaction temperature. An initial 2,3,7,8-TeCDD concentration of 20 ng l −1 was completely degraded within 60 min under sonochemical conditions using a 20 kHz frequency with a 150 W ultrasound power. The activation energy is 21.9 kJ/mol in the temperature range of 10–40 °C, suggesting a diffusion-controlled reaction. To increase the efficiency of 2,3,7,8-TeCDD treatment, degradation system combined ultrasound with Fe(III) (2 × 10 −4  mol l −1 ) and UV irradiation. Both UV and Fe(III) induced Fenton, Fenton-like and photo-Fenton reactions, leading to additional OH radicals and rapid 2,3,7,8-TeCDD removal.