SONOCHEMICAL DEGRADATION OF ETHYLBENZENE IN AQUEOUS-SOLUTION - A PRODUCT STUDY

The degradation of ethylbenzene in aqueous solution by 520 kHz ultraso und was investigated. The products formed were analysed using solid ph ase microextraction (SPME), a sampling technique that allows convenien t GC-MS and GC-FID analysis in the micromolar range. A broad range of monosubstituted monocyclic and dicyclic aromatic hydrocarbons was foun d as well as some oxygenated products. The results clearly indicate th at pyrolysis is an important pathway of ethylbenzene degradation. The side chain is dehydrogenated, forming styrene, or cleaved. The radical s formed upon cleavage are subsequently added to the double bond of th e styrene side chain or recombined. This mechanism explains the format ion of most of the products. Formation and breakdown of the reaction p roducts follow first-order kinetics in spite of the fact that the sele ctivity of the reactions depends on the initial ethylbenzene concentra tion considerably. Changes in the temperature and the pressure of cavi tation are expected to cause this dependence. (C) 1997 Elsevier Scienc e B.V.