The Kinetics of the Sonochemical Process for the Destruction of Aliphatic and Aromatic Hydrocarbons

The sonochemical destruction of volatile organic compounds in aqueous solution has been investigated by using TCE (trichloroethylene), PCE (tetrachloroethylene), benzene, and toluene as model compounds. The substrate's destruction was observed to be decreased at a pseudo first-order rate, and the rate of TCE decay (K_o=1.7×10^-3 s^-1) was the greatest when the initial concentration of TCE was 380 μM. The effect of initial concentrations of TCE (ranging from [TCE]_o=8.5-424 μM) on the overall decomposition rate of TCE, k_o,TCE was investigated. The k_o value decreases with the increase of [TCE]_o to the level of 200 μM. But, the stays constant increasing the [TCE]_o further. The effect of bicarbonate on TCE decomposition at low concentrations was investigated. The bicarbonate affects TCE decomposition insignificantly in the spiked bicarbonate range of 1 to 10 mM. The sonolytic rate of degradation of TCE appears to be enhanced by the presence of ozone, and the enhancement degree was quite significant at low concentrations of substrate. A kinetic model study was attempted to elucidate the specific reaction sites of the tested compounds and the major contribution of destruction route (OH• reaction or pyrolysis reaction) depending on the various conditions.