Aqueous sonolytic decomposition of polycyclic aromatic hydrocarbons in the presence of additional dissolved species

Abstract

Sonochemical degradation of aqueous polycyclic aromatic hydrocarbons (PAHs) results in a first-order loss of the PAHs ( k=0.010–0.027 s −1 ). When sonication occurred in the presence of other organic compounds, the degradation rate constant was reduced quite dramatically. This reduction is believed to come about through scavenging of radicals by the matrix chemical. When oxygen was bubbled into the PAH solution before sonication, the degradation rate constant was elevated. Nitrogen purging resulted in decreased rate constants. These results indicate that oxygen was an important precursor in the degradation of the PAHs. Organic compounds, including humic acid, benzoic acid, and sodium dodecyl sulfate, decreased PAH degradation rate constants by scavenging oxygen derived reactive transients.