Volume 30 Issue 7 - July 1, 2016 PDF
Interaction of ciprofloxacin and probe compounds with palygorskite
Po-Hsiang Chang1, Wei-Teh Jiang1,*, Zhaohui Li2, Chung-Yih Kuo3, Qingfeng Wu4, Jiin-Shuh Jean1, Guocheng Lv5
1 Department of Earth Sciences, National Cheng Kung University, Taiwan
2 Department of Geosciences, University of Wisconsin-Parkside, USA
3 Department of Public Health, Chung Shan Medical University, Taiwan
4 College of Physics and Technology, Yangtze University, China
5 School of Materials Science and Technology, China University of Geosciences, China
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Fluoroquinolone antibiotics have been widely used in human therapy, veterinary treatment and aquaculture applications and imperceptibly become harmful to the environment through time. Clay minerals as a major host of many organic compounds have often been utilized to remove organic contaminants in various aqueous conditions. Like most of other fluoroquinolones, ciprofloxacin possesses more than one polar functional group and may participate in multiple sorption interactions. The involvement of multiple interaction mechanisms related to different groups in ciprofloxacin adsorption at various pHs could result in the complexity of identification of each mechanism. With the use of stereochemically-related probe compounds in this study, we were able to determine the key functional groups that operated specific adsorption and interaction mechanisms in the adsorption of ciprofloxacin onto a fibrous clay mineral palygorskite under acidic to alkaline conditions. The result demonstrated that palygorskite could adsorb ciprofloxacin effectively by a cation exchange mechanism via the protonated piperazine amine group in acidic to neutral solution, and moderately through cation bridging or surface complexation correlated with the deprotonated keto carbonyl group in alkaline solution (Fig. 1). The findings allow prediction of interactions between fluoroquinolones and other media.
Fig. 1. The contact models of ciprofloxacin adsorption on palygorskite under acidic to neutral and alkaline conditions, respectively.
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