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Title: Surface interactions and degradation of a fluoroquinolone antibiotic in the dark in aqueous TiO2 suspensions

Fluoroquinolone antibiotics (FQs) are important drugs used in human and veterinary medicine. Their detection in natural waters and waste water treatment plants, along with increased resistance to FQs among some bacteria, have generated an increased interest in the fate of these drugs in the environment. Partitioning of FQs between an aqueous solution and attendant substrates depends, in part, on the surface reactivity of the adsorbent, commonly a function of particle size, surface charge, and functional groups. In this paper, this study investigated the surface interactions between the FQ drug ofloxacin (OFL) and titanium oxide (TiO2), a common catalyst and widely-observed constituent in many consumer products. Raman and fluorescence spectroscopic techniques, as well as LC/MS, were used to determine the OFL moieties present on TiO2 surfaces and in attendant solutions. Raman spectra indicate that the C==O (ketone) group of the quinolone core, the NH+ of the piperazinyl ring, and CH3 of benzoxazine core are the most active in sorption onto the TiO2 surface. Raman spectra also show that the sorbed benzoxazine–quinolone core and piperazinyl moieties are readily desorbed from the surface by re-suspending samples in water. Importantly, we found that OFL could be degraded by reacting with TiO2 even in themore » dark. Complementary LC/MS analysis of the attendant supernatants indicates the presence of de-piperazinylated and de-carboxylated OFL breakdown products in supernatant solutions. Together, both Raman and LC/MS analyses indicate that TiO2 breaks the compound into piperazinyl and carboxylate groups which attach to the surface, whereas de-carboxylated and hydroxylated quinolone moieties remain in solution. Finally, the present study thus identifies the sorption mechanisms and breakdown products of OFL during dark reactions with TiO2, which is critically important for understanding the fate and transport of OFL as it enters the soil and aquatic environment.« less
 [1] ;  [2] ;  [3]
  1. Hope College, Holland, MI (United States). Dept. of Geological and Environmental Sciences
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division
  3. Hope College, Holland, MI (United States). Dept. of Chemistry
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Science of the Total Environment
Additional Journal Information:
Journal Volume: 532; Journal ID: ISSN 0048-9697
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
60 APPLIED LIFE SCIENCES; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY Fluoroquinolone degradation; Titanium oxide nanoparticles; Ofloxacin; Antibiotics in wastewater; PPCP contamination