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| Adsorption and desorption mechanisms of trimethoprim on clay minerals |
| Received:August 20, 2021 |
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| KeyWord:kaolinite;montmorillonite;trimethoprim;adsorption;desorption |
| Author Name | Affiliation | E-mail | | LI Yanyun | Key Laboratory of Water Resources and Environment Engineering, School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China | | | WEI Yanan | Key Laboratory of Water Resources and Environment Engineering, School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China | | | BI Erping | Key Laboratory of Water Resources and Environment Engineering, School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China | bi@cugb.edu.cn |
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| Abstract: |
| In this study, kaolinite and montmorillonite were used as adsorbents, Na+ and L-Lysine（Lys）were selected as coexisting components, and the adsorption / desorption characteristics of different forms of trimethoprim（TMP）on clay minerals were investigated through batch experiments. The results showed that TMP adsorption onto kaolinite and montmorillonite reached equilibrium within 24 h. The adsorption kinetic characteristics of montmorillonite on TMP were affected by the competitive adsorption of H + in solution and the form of TMP. The main adsorption mechanisms of TMP were cation exchange, electrostatic attraction, and intermolecular force, while the adsorption coefficient was affected by the ratio of TMP+/TMP0 and the strength of the sorption interaction. Due to the different pH buffering capacities and surface charges of the two clay minerals, when the initial concentration of TMP was 1 mg?L-1 and the initial solution pH was 6, the coexistence of Na+ and Lys+ inhibited the adsorption of TMP onto kaolinite but promoted its adsorption onto montmorillonite. In the desorption experiments, TMP+ and TMP0 were the main species existing in the kaolinite and montmorillonite systems, respectively. Because the binding strength of cation exchange and electrostatic attraction is much stronger than the intermolecular force, the desorption ratio of TMP from montmorillonite was approximately 4~5 times that of kaolinite. |
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