Utilization of electrochemically generated ozone in the degradation and detoxification of aqueous polycyclic aromatic hydrocarbons

Previously, ozonation of aqueous polycyclic aromatic hydrocarbons (PAHs) resulted in reduction or enhancement of toxicity depending on the conditions of ozonation, the particular PAH, and the bioassay utilized. In addition, these ozonation studies have been conducted in a preponderance of organic solvents that can affect the kinetics of the products formed. The potential application of ozone to the reclamation of waste, ground, and drinking water necessitates the need for toxicological assessments under predominantly aqueous conditions and over a series of timed treatment doses of ozone. Furthermore, there is a need for an effective chemical analysis technique for following the degradation products.; The degradation and detoxification of two model PAHs, benzo[a]pyrene (BaP) and pyrene, were examined following treatment with electrochemically generated ozone. The rapid degradation of BaP and pyrene following aqueous ozonation was consistent with past studies. While only a few ozonation products were observed, the data indicated that some pyrene ozonation products might be persistent. The toxicity of BaP and pyrene ozonation products was assessed using a chicken embryotoxicity screening test (CHEST) and a gap junction mediated intercellular communication (GJIC) assay. Pyrene and BaP ozonation products exhibited significant toxicity in the GJIC assay, producing their greatest effects at 5 to 6 min and 1 min of ozonation, respectively. The effects on GJIC were eliminated for both compounds given sufficient ozonation time. No significant increase in mortality or embryotoxicity was observed in the CHEST assay with either ozonated BaP or pyrene.; Benzo[a]pyrene and pyrene were examined for product formation using flow injection analysis/mass spectrometry. The results indicated a complex reaction in which BaP formed numerous products, while pyrene formed fewer products that resisted further oxidation by ozone. The formation of lower molecular weight products correlated with decreased toxicity in the GJIC assay.; Three mixtures of PAHs were assessed, following ozonation, for potential interactions. No synergistic or antagonistic interactions in ozonated PAH mixtures were observed. However, the data suggested that symmetrical or small PAHs react with ozone in a manner causing the formation of products that require significantly longer ozonation times to alleviate their toxic effects.