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Front. Chem. | doi: 10.3389/fchem.2018.00016

The interactions between three typical PPCPs and LDH

Erwei Li1, Guocheng Lv1*,  Libing Liao1*, Zhaohui Li2* and Chengxue Yang1
  • 1School of Materials Science and Technology, China University of Geosciences, China
  • 2Geosciences Department, University of Wisconsin–Parkside, United States

With a positively charged layered structure, layered double hydroxide has potential applications in remediation of anionic contaminants, which has been a hot topic for recent years. In this study, a Cl type Mg-Al hydrotalcite (Cl-LDH) was prepared by a co-precipitation method. The adsorption process of three pharmaceuticals and personal care products (PPCPs) (tetracycline (TC), diclofenac sodium (DF), chloramphenicol (CAP)) by Cl-LDH was investigated by X-ray diffraction (XRD), Zeta potential, dynamic light scattering (DLS), BET, FT-IR spectroscopy and molecular dynamics simulation. The results showed that the adsorption equilibrium of TC and DF could be reached in 120 min, and the maximum adsorption capacity of the Cl-LDH for TC and DF were 1.85 mmol/g and 0.95 mmol/g, respectively. The adsorption isothermal of TC was fitted with the Freundlich adsorption model, and the adsorption isothermal of DF was fitted with the Langmuir adsorption model. The adsorption dynamics of TC and DF followed the pseudo-second-order model. The adsorption mechanisms of the three PPCPs onto Cl-LDH were different based on the experimental results and molecular dynamics simulation. The TC adsorption on Cl-LDH was mainly driven by the electrostatic interactions between the negative charge of TC and the positive charge of Cl-LDH. The uptake of anionic DF was attributed both to ion exchange of DF for Cl- and the electrostatic interaction between the negatively charged DF and the positively charged structure layer of Cl-LDH. Cl-LDH does not adsorb the neutral CAP due to no electrostatic interaction. The molecular dynamic simulation further confirmed different configurations of the three selected PPCPs in the interlayer of Cl-LDH, which were responsible for the different uptake process of PPCPs on Cl-LDH.

Keywords: Cl-LDH, PPCPs, TC, df, CAP, Adsorption, simulation

Received: 10 Nov 2017; Accepted: 19 Jan 2018.

Edited by:

Aiqin Wang, Lanzhou Institute of Chemical Physics (CAS), China

Reviewed by:

Hui-Fang Cui, Zhengzhou University, China
Wenbo Wang, Lanzhou Institute of Chemical Physics (CAS), China
Runliang Zhu, Guangzhou Institute of Geochemistry (CAS), China  

Copyright: © 2018 Li, Lv, Liao, Li and Yang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Prof. Guocheng Lv, China University of Geosciences, School of Materials Science and Technology, Beijing, China, guochenglv@cugb.edu.cn
Prof. Libing Liao, China University of Geosciences, School of Materials Science and Technology, Beijing, China, clayl@cugb.edu.cn
Prof. Zhaohui Li, University of Wisconsin–Parkside, Geosciences Department, Kenosha, United States, li@uwp.edu