In Situ Spectroscopic Investigations of Adsorption Mechanisms of Nitroaromatic Compounds at Clay Minerals
| Autor: | Kenneth W. Weissmahr, Rolf Nüesch, Rene P. Schwarzenbach, Roland Hany, Stefan B. Haderlein |
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| Rok vydání: | 1996 |
| Předmět: | |
| Zdroj: | Environmental Science & Technology. 31:240-247 |
| ISSN: | 1520-5851 0013-936X |
| DOI: | 10.1021/es960381+ |
| Popis: | Nitroaromatic compounds (NACs) including a number of priority pollutants such as explosives (e.g., TNT) and herbicides (e.g., DNOC) have been shown to adsorb strongly and specifically at natural clays. In situ spectroscopic techniques (13C-NMR, ATR-FTIR, UV/VIS, XRD) were applied to investigate the adsorption mechanism(s) of NACs at clays in aqueous systems. Planar NACs with several electron-withdrawing substituents exhibited highest sorption and were used as model compounds. The combined experimental evidence suggests a n−π electron donor−acceptor (EDA) complex between oxygens of the siloxane surface(s) of the clays (e- donors) and NACs (e- acceptors). Other adsorption mechanisms such as H-bonding or direct coordination of NO2 groups to surface sites were not important in aqueous environments, but contributed to the adsorption of NACs from apolar solvents. EDA complex formation took place at both external and, to a lesser extent, interlamellar siloxane surfaces of expandable clays. Adsorbed NACs were ori... |
| Databáze: | OpenAIRE |
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