269-2 Molecular Mechanisms of Oxytetracycline and Ciprofloxacin Sorption On Nano-Magnetite.

See more from this Division: S02 Soil Chemistry
See more from this Session: The Solid-Solution Interface Chemistry: Oxides, Sulfides Et Al.: I
Tuesday, October 23, 2012: 3:30 PM
Duke Energy Convention Center, Room 207, Level 2
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Sudipta Rakshit1, Dibyendu Sarkar1, Evert J. Elzinga2 and Rupali Datta3, (1)Department of Earth and Environmental Studies, Montclair State University, Montclair, NJ
(2)Rutgers, The State University of New Jersey, Newark, NJ
(3)Department of Biological Sciences, Michigan Technological University, Houghton, MI
Nano-magnetite (nano-Fe3O4), which has been reported to form on the outer surface of nano-iron, is an important nano-iron species in remediation science. Recent studies demonstrated the potential of nano-Fe3O4 to become a good sorbent for certain antibiotics.  However, molecular level investigations of the interaction mechanisms of antibiotics with nano-Fe3O4 are lacking. To probe the interaction mechanisms of antibiotics with nano-Fe3O4 at the molecular level, we used two commonly prescribed antibiotics, one from the tetracycline group: oxytetracycline (OTC), and another from the fluoroquinolone group: ciprofloxacin (CIP).  Wet chemical, spectroscopic, and surface complexation modeling (SCM) approaches were employed to understand the interaction mechanisms.  Batch Sorption experiments with OTC and CIP and nano-Fe3O4 were performed as a function of different solution properties such as pH (~3-10), ionic strength (~0.01-0.5), and initial antibiotic concentrations (0.01-1 mM).  In situ ATR-FTIR experiments were conducted using 5-25 µM OTC/CIP at pH range of 3-9.  Results indicated high affinity of nano-Fe3O4 towards both OTC and CIP.  Sorption envelope indicated that retention of OTC and CIP on nano-Fe3O4 was highly pH-dependent.  FTIR data showed that amide (-CONH2), dimethyl amino (-N(CH3)2), and phenolic-OH functional groups of OTC participated in the sorption reaction.  For CIP, main functional groups that interacted with nano-Fe3O4 surfaces are carboxyl (-COOH) and keto (>C=O).  While no surface complexes could be identified for OTC, a bridging-bidentate surface complex was proposed for CIP.  Analysis of ATR-FTIR data revealed that interactions of OTC and CIP with nano-Fe3O4 were inner-sphere.  Our research indicates that nano-Fe3O4 has the potential to become a remediation material for antibiotics.
See more from this Division: S02 Soil Chemistry
See more from this Session: The Solid-Solution Interface Chemistry: Oxides, Sulfides Et Al.: I