Sonochemical decomposition of dibenzothiophene in aqueous solution

Dibenzothiophene is decomposed rapidly by sonication in aqueous solution. Decomposition of dibenzothiophene follows a first-order reaction kinetics. The rate constant was found to increase with increasing ultrasonic energy intensity, temperature, and pH and decrease with increasing initial dibenzothiophene concentration. The activation energy was 12.6 kJ/mol in the temperature range of 15–50°C, suggesting a diffusion-controlled reaction. Hydroxydibenzothiophenes and dihydroxydibenzothiophenes were identified as reaction intermediates. It is proposed that dibenzothiophene is oxidized by OH radical to hydroxy-dibenzothiophenes and then to dihydroxy-dibenzothiophenes. Kinetic analysis suggests that approximately 72% of the dibenzothiophene decomposition occurred via OH radical addition. A pathway and a kinetic model for the sonochemical decomposition of dibenzothiophene in aqueous solution are proposed.