ENVR 168 |
| Fluoroquinolones are an important class of clinical antibacterial agents and an established class of aquatic micropollutants. The presence of these potent antibacterial agents in the aquatic environment raises particular concerns about their potential for increasing antibacterial resistance in pathogens. In a previous study, we demonstrated fluoroquinolone transformation via UV- and visible light-photocatalysis processes in irradiated TiO2-containing solutions and proposed a charge-transfer mechanism for visible-TiO2 photocatalysis that may enable targeted treatment of fluoroquinolones within a mixed aqueous matrix; however, the antimicrobial potency of the products (or lack thereof) was not established. In the present study, the residual antimicrobial activity of degradation products generated during UV photolysis and UV- and visible-light mediated TiO2 photocatalytic treatment of ciprofloxacin, a model fluoroquinolone, has been quantified using in vitro bioassays with a reference E. coli strain. Bioassay results indicate that for each mole of ciprofloxacin degraded, the potency of treated solutions decreases by approximately one "mole" relative to that of the untreated ciprofloxacin solution, suggesting that the antibacterial potencies of photo(cata)lysis degradation products are substantially lower than the parent molecules. Practical implications of these findings will also be discussed in terms of the relative energy inputs required for ciprofloxacin deactivation by each treatment process. |
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Advances in Abiotic Transformation Processes for Micropollutants in Drinking Water and for Sourcewater Protection
8:30 AM-12:10 PM, Wednesday, April 9, 2008 Morial Convention Center -- Rm. 237, Oral
Division of Environmental Chemistry |