Interactions of oxytetracycline with a smectite clay: A spectroscopic study with molecular simulations

Ludmilla Aristilde*, Claire Marichal, Jocelyne Miéhé-Brendlé, Bruno Lanson, Laurent Charlet

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

113 Scopus citations


Binding of antibiotics to clay minerals can decrease both their physical and biological availability in soils. To elucidate the binding mechanisms of tetracycline antibiotics on smectite clays as a function of pH, we probed the interactions of oxytetracycline (OTC) with Na-montmorillonite (MONT) using X-ray diffraction (XRD), infrared (IR), and solid-state nuclear magnetic resonance (NMR) spectroscopies, and Monte Carlo molecular simulations. The XRD patterns demonstrate the presence of OTC in the MONT interlayer space at acidic pH whereas complexation of OTC by external basal and edge sites seems to prevail at pH 8. At both pH, the 1H-13C NMR profile indicates restricted mobility of the adsorbed OTC species; and, -CH3 deformation and C-N stretching IR vibration bands confirm a binding mechanism involving the protonated dimethylamino group of OTC. Changes in the 23Na NMR environments are consistent with cation-exchange and cation complexation reactions at the different sites of adsorption. Molecular simulations indicate that MONT interlayer spacing and structural charge localization dictate favorable binding conformations of the intercalated OTC, facilitating multiple interactions in agreement with the spectroscopic data. Our results present complementary insights into the mechanisms of adsorption of TETs on smectites important for their retention in natural and engineered soil environments.

Original languageEnglish (US)
Pages (from-to)7839-7845
Number of pages7
JournalEnvironmental Science and Technology
Issue number20
StatePublished - Oct 15 2010

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

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