Clays and Clay Minerals, Vol. 58, No. 4, 462–474, 2010.
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Authors
Li, Zhaohui
Kolb, Vera M.
Jiang, Wei-teh
Hong, Hanlie
Issue Date
2010
Type
Article
Language
Keywords
Periodicals , Geology , Cation Exchange , Complexation , Deuterated Tetracycline , pH , Swelling Clay , Surface Adsorption
Alternative Title
FTIR And Xrd Investigations Of Tetracycline Intercalation In Smectites
Abstract
Due to swelling, smectite minerals are capable of intercalating many organic molecules in their interlayer space. Tetracycline (TC) is a group of antibiotics used extensively in human and veterinary medicine. The great aqueous solubility and long environmental half life of TC mean that the study of interactions between swelling clay minerals and TC are of great importance in TC transport and retention in subsurface soils. In the present study, the intercalation of TC molecules at different levels into smectites was investigated using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The shift of the FTIR bands of amide I and II in comparison to crystalline TC suggested a strong interaction between the amide groups and the clay surfaces. The band at 1455 cm-1 remained the same after TC intercalation into SAz-1, SWy-2, and SYn-1, suggesting that complexation was not a dominant mechanism of TC uptake by these minerals. With cation exchange as the major mechanism of TC intercalation into these minerals, simultaneous removal of H+ from solution protonated the TC molecules and provided a positive charge to interact with negatively charged mineral surfaces even in neutral to slightly alkaline conditions. The increase in interlayer distance after intercalation by TC, as revealed by XRD, suggested a tilted orientation of the intercalated TC molecules in both twisted conformation in acidic condition and extended conformation in alkaline condition.
Description
gsccm58402-li.pdf -- 510KB
Citation
Clays and Clay Minerals, Vol. 58, No. 4, 462–474, 2010.
Publisher
The Clay Minerals Society
License
Copyright © 2006-2018
Journal
Volume
Issue
PubMed ID
DOI
ISSN
DOI: 10.1346/CCMN.2010.0580402