Abstract
Raman spectroscopy was used to investigate sorption mechanisms of cephapirin (CHP), a veterinary antibiotic, onto quartz (SiO2) and feldspar (KAlSi3O8) at different pH. Sorption occurs by electrostatic attraction, monodentate and bidentate complexation. The zwitterion (CHPo) adsorbs to a quartz(+) surface by electrostatic attraction of the carboxylate anion group (-COO-) at low pH, but adsorbs to a quartz(-) surface through electrostatic attraction of the pyridinium cation, and possibly COO- bridge complexes, at higher pH. CHP- bonds to quartz(-) surfaces by bidentate complexation between one oxygen of -COO- and oxygen from carbonyl of an acetoxymethyl group. On a feldspar(+/-) surface, CHPo forms monodentate complexes between C{double bond, long}O, and possible -COO- bridges and/or electrostatic attachments to localized edge (hydr)oxy-Al surfaces. CHP- adsorbs to feldspar(-) through monodentate C{double bond, long}O complexation. Similar mechanisms may operate for other cephalosporins. Results demonstrate, for the first time, that Raman techniques can be effective for evaluating sorption mechanisms of antibiotics.
Original language | English |
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Pages (from-to) | 1849-1856 |
Number of pages | 8 |
Journal | Environmental Pollution |
Volume | 157 |
Issue number | 6 |
DOIs | |
State | Published - Jun 2009 |
Externally published | Yes |
Funding
This work was funded in part by a Howard Hughes Medical Institute Undergraduate Science Program Grant to Hope College and by the Michigan Space Grant Consortium. Additional financial support was provided by the GLCA–ACM Oak Ridge Science Semester Program, Hope College Department of Chemistry and the Hope College Department of Geological and Environmental Sciences. BG and WW were supported by the Office of Biological and Environmental Research, US Department of Energy (DOE). Oak Ridge National Laboratory is managed by UT-Battelle LLC for US DOE under contract DE-AC05-00OR22725. Comments and suggestions from anonymous reviewers were greatly appreciated.
Keywords
- Cephalosporins
- Raman spectroscopy
- Sorption mechanisms
- Veterinary antibiotics