Fluoroquinolones and quinolone antibiotics have been detected in levels several hundred ng per L in wastewater effluents, ground water and surface waters throughout the world. The fate and behavior of these antibiotics in the environment are consequently a growing concern in current-day studies. Their adsorption at mineral surfaces has been extensively studied over the past 20 years, yet much remains to be learned on their interfacial properties and transformation mechanisms. Here, interactions of oxolinic acid (OA), a quinolone antibiotic used in aquaculture, and ciprofloxacin (CIP), a fluoroquinolone antibiotic used in human and veterinary medicine, with synthetic goethite (a-FeOOH), hematite (α-Fe2O3) and akaganéite (b-FeOOH) particle surfaces were monitored to understand the potential fate of OA and CIP in marine sediments where these phases occur. Batch sorption experiments, liquid chromatography (LC), mass spectrometry (MS) and Attenuated Total Reflectance-Fourier Transform InfraRed (ATR-FTIR) spectroscopy and multi-site complexation (MUSIC) modeling were used to monitor OA and CIP binding at these particle surfaces. Both LC/MS and ATR-FTIR also showed that adsorption did not degrade OA, while the sorbed mother CIP molecule decayed to other surface species over a period of at least 65 h. This latter was supported by the detection of three daughter products in aqueous phase by LC/MS. ATR-FTIR spectroscopy provides evidence for inner-sphere bidentate complex formation of CIP at hematite surfaces, irrespective of pH and particle size. For OA, formation of metal-bonded complexes at circumneutral to low pHc (= - log [H+]) and with a strongly hydrogen-bonded complex at high pHc was expected. Collectively, these findings revealed that Fe-oxyhydroxides may strongly contribute to the fate and transport of antibacterial agents in marine sediments and waters.

Binding of antibacterial agents at Fe(III) oxyhydroxide surfaces: Experimental study and modeling

253rd National Meeting (2017)

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