Enhanced adsorption of bisphenol A, tylosin, and tetracycline from aqueous solution to nitrogen-doped multiwall carbon nanotubes via cation-π and π-π electron-donor-acceptor (EDA) interactions

Langsha Yi; Linzi Zuo; Chenhui Wei; Heyun Fu; Xiaolei Qu; Shourong Zheng; Zhaoyi Xu; Yong Guo; Hui Li; Dongqiang Zhu

doi:10.1016/j.scitotenv.2020.137389

Enhanced adsorption of bisphenol A, tylosin, and tetracycline from aqueous solution to nitrogen-doped multiwall carbon nanotubes via cation-π and π-π electron-donor-acceptor (EDA) interactions

Sci Total Environ. 2020 Jun 1:719:137389. doi: 10.1016/j.scitotenv.2020.137389. Epub 2020 Feb 19.

Authors

Langsha Yi¹, Linzi Zuo², Chenhui Wei¹, Heyun Fu³, Xiaolei Qu³, Shourong Zheng³, Zhaoyi Xu³, Yong Guo⁴, Hui Li⁵, Dongqiang Zhu⁶

Affiliations

¹ School of Urban and Environmental Sciences, Key Laboratory of the Ministry of Education for Earth Surface Processes, Peking University, Beijing 100871, China.
² Analysis and Test Center, Guangdong University of Technology, Guangzhou 510006, China.
³ School of the Environment, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing University, Jiangsu 210093, China.
⁴ Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Jiangsu 210090, China.
⁵ Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, United States.
⁶ School of Urban and Environmental Sciences, Key Laboratory of the Ministry of Education for Earth Surface Processes, Peking University, Beijing 100871, China. Electronic address: zhud@pku.edu.cn.

PMID: 32120097
DOI: 10.1016/j.scitotenv.2020.137389

Abstract

Doping heteroatoms in carbon nanotubes can substantially enhance the electronic polarizability of the carbon surface and thus may facilitate adsorptive interactions of organic contaminants. Here, the adsorption isotherms of three polar/ionizable emerging organic contaminants, bisphenol A, tylosin, and tetracycline from aqueous solutions to synthesized heteroatom nitrogen-doped multiwall carbon nanotubes (N-MCNT) were compared with those to commercial non-doped multiwall carbon nanotubes (MCNT) at pH ~ 6. N-MCNT exhibited much stronger adsorption (3-4 folds higher sorption distribution coefficients, K_d) towards the three adsorbates than MCNT. The hydroxyl group-substituted bisphenol A molecule is rich in π-electrons and thus interacts with the polarized π-electron-depleted N-heterocyclic aromatic ring on N-MCNT via π-π electron-donor-acceptor (EDA) interaction, whereas the protonated amino group and enone groups in the tylosin molecule are deficient in electrons and interact with the neighboring π-electron-rich aromatic ring on N-MCNT via cation-π and π-π EDA interactions, respectively. The tetracycline molecule contains both electron-rich moiety (phenol ring) and electron-depleted moieties (protonated amino group and enone groups), which interact with the corresponding π-electron-acceptor/donor sites on N-MCNT. The proposed adsorption mechanisms were tested by the effects of ionic strength (NaCl or CaCl₂), co-present Cu²⁺ ion, and changing pH on adsorption, and further by the adsorption behavior of a model organic cation (tetraethylamine). These results indicate that enhanced adsorption of emerging organic contaminants to carbon nanotubes can be achieved by doping with heterocyclic nitrogen atoms to facilitate specific EDA interactions. Capsule: Nitrogen-doped multiwall carbon nanotubes exhibit enhanced adsorptive removal of bisphenol A, tylosin, and tetracycline from aqueous solutions.

Keywords: Adsorption; Bisphenol A; Electron-donor-acceptor interaction; Nitrogen-doped carbon nanotubes; Tetracycline; Tylosin.

MeSH terms

Adsorption
Benzhydryl Compounds
Cations
Electrons
Nanotubes, Carbon*
Nitrogen
Phenols
Tylosin

Substances

Benzhydryl Compounds
Cations
Nanotubes, Carbon
Phenols
bisphenol A
Nitrogen
Tylosin