Selective adsorption of Pb2+ and Cu2+ on amino-modified attapulgite: Kinetic, thermal dynamic and DFT studies

Lei Xu; Yani Liu; Jingang Wang; Ying Tang; Zhe Zhang

doi:10.1016/j.jhazmat.2020.124140

Selective adsorption of Pb²⁺ and Cu²⁺ on amino-modified attapulgite: Kinetic, thermal dynamic and DFT studies

J Hazard Mater. 2021 Feb 15;404(Pt A):124140. doi: 10.1016/j.jhazmat.2020.124140. Epub 2020 Oct 1.

Authors

Lei Xu¹, Yani Liu², Jingang Wang³, Ying Tang¹, Zhe Zhang⁴

Affiliations

¹ Key Laboratory of Eco-Environment-Related Polymer Materials of Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China.
² Key Laboratory of Eco-Environment-Related Polymer Materials of Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China; College of Science, Gansu Agricultural University, Lanzhou 730070, China.
³ Computational Center for Property and Modification on Nanomaterials, College of Sciences, Liaoning University of Petroleum and Chemical Technology, Fushun 113001, China.
⁴ Key Laboratory of Eco-Environment-Related Polymer Materials of Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China. Electronic address: zhangzhe@nwnu.edu.cn.

PMID: 33070005
DOI: 10.1016/j.jhazmat.2020.124140

Abstract

Amino-modified attapulgite (M-ATP) was prepared to remove Pb²⁺ and Cu²⁺ from the aqueous solution. Fourier transform infrared spectroscopy (FT-IR) spectrums and X-ray powder diffraction (XRD) patterns revealed that a new Si-O-Si bond formed after modification. The result indicates that the graft reaction of ATP occurred at Si-O (2 0 0) tetrahedron crystal face. No matter whether in a single or binary heavy metal ion system, the adsorption experiments displayed that the equilibrium adsorption capacity of M-ATP towards Pb²⁺ was much higher than Cu²⁺, which indicated M-ATP more readily adsorbs the Pb²⁺. The selective adsorption mechanism of Pb²⁺ and Cu²⁺ on modified attapulgite was studied by density functional theory (DFT). The E_ads of Pb (- 2.01 eV) adsorbed on M-ATP is lower than Cu (- 1.79 eV) through the DFT calculation of adsorption energy (E_ads), which indicate that the Pb²⁺ adsorbed on M-ATP is more stable than Cu²⁺. Both adsorption experiments and theoretical calculations revealed that due to the stability of Pb²⁺ adsorption on M-ATP, Pb²⁺ is more readily adsorbed by M-ATP, and it is difficult for Cu²⁺ to exchange Pb²⁺ from M-ATP.

Keywords: Attapulgite; Heavy metals; Selective adsorption; Theoretical calculation.

Publication types

Research Support, Non-U.S. Gov't