Sonochemical decomposition of dibenzothiophene in aqueous solution

Dibenzothiophene is decomposed rapidly by sonication in aqueous solution. D ecomposition of dibenzothiophene follows a first-order reaction kinetics. T he rate constant was found to increase with increasing ultrasonic energy in tensity, temperature, and pH and decrease with increasing initial dibenzoth iophene concentration. The activation energy was 12.6 kJ/mol in the tempera ture range of 15-50 degreesC, suggesting a diffusion-controlled reaction, H ydroxydibenzothiophenes and dihydroxydibenzothiophenes were identified as r eaction intermediates. It is proposed that dibenzothiophene is oxidized by OH radical to hydroxy-dibenzothiophenes and then to dihydroxy-dibenzothioph enes. Kinetic analysis suggests that approximately 72% of the dibenzothioph ene decomposition occurred via Oil radical addition. A pathway and a kineti c model for the sonochemical decomposition of dibenzothiophene in aqueous s olution are proposed. (C) 2001 Elsevier Science Ltd. All rights reserved.