TY - JOUR
T1 - Ab initio calculation of the adsorption of As, Cd, Cr, and Hg heavy metal atoms onto the illite(001) surface
T2 - Implications for soil pollution and reclamation
AU - Qi, Chongchong
AU - Xu, Xinhang
AU - Chen, Qiusong
AU - Liu, Hui
AU - Min, Xiaobo
AU - Fourie, Andy
AU - Chai, Liyuan
N1 - Funding Information:
This work was supported by National Natural Science Foundation of China (No. 52004330 , 52104156 ). This work was also supported by resources provided by the Pawsey Supercomputing Centre with funding from the Australian Government and the Government of Western Australia .
Publisher Copyright:
© 2022 Elsevier Ltd
PY - 2022/11/1
Y1 - 2022/11/1
N2 - Elucidating the mechanisms of heavy metal (HM) adsorption on clay minerals is key to solving HM pollution in soil. In this study, the adsorption of four HM atoms (As, Cd, Cr, and Hg) on the illite(001) surface was investigated using density functional theory calculations. Different adsorption configurations were investigated and the electronic properties (i.e., adsorption energy (Ead) and electron transfer) were analyzed. The Ead values of the four HM atoms on the illite(001) surface were found to be As > Cr > Cd > Hg. The Ead values for the most stable adsorption configurations of As, Cr, Cd, and Hg were −1.8554, −0.7982, −0.3358, and −0.2678 eV, respectively. The As atoms show effective chemisorption at all six adsorption sites, while Cd, Cr, and Hg atoms mainly exhibited physisorption. The hollow and top (O) sites were more favorable than the top (K) sites for the adsorption of HM atoms. The Gibbs free energy results show that the illite(001) surface was energetically favorable for the adsorption of As and Cr atoms under the influence of 298 K and 1 atm. After adsorption, there was a redistribution of positions and reconfiguration of the chemical bonding of the surface atoms, with a non-negligible influence around the upper surface atoms. Bader charge analysis shows electrons were transferred from the surface to the HM atoms, and a strong correlation between the valence electron variations and the adsorption energy was observed. HM atoms had a high electronic state overlap with the surface O atoms near the Fermi energy level, indicating that the surface O atoms, though not the topmost atoms around the surface, significantly influence HM adsorption. The above results show illite(001) preferentially adsorbed As among all four investigated HM atoms, indicating that soils containing a high proportion of illite might be more prone to As pollution.
AB - Elucidating the mechanisms of heavy metal (HM) adsorption on clay minerals is key to solving HM pollution in soil. In this study, the adsorption of four HM atoms (As, Cd, Cr, and Hg) on the illite(001) surface was investigated using density functional theory calculations. Different adsorption configurations were investigated and the electronic properties (i.e., adsorption energy (Ead) and electron transfer) were analyzed. The Ead values of the four HM atoms on the illite(001) surface were found to be As > Cr > Cd > Hg. The Ead values for the most stable adsorption configurations of As, Cr, Cd, and Hg were −1.8554, −0.7982, −0.3358, and −0.2678 eV, respectively. The As atoms show effective chemisorption at all six adsorption sites, while Cd, Cr, and Hg atoms mainly exhibited physisorption. The hollow and top (O) sites were more favorable than the top (K) sites for the adsorption of HM atoms. The Gibbs free energy results show that the illite(001) surface was energetically favorable for the adsorption of As and Cr atoms under the influence of 298 K and 1 atm. After adsorption, there was a redistribution of positions and reconfiguration of the chemical bonding of the surface atoms, with a non-negligible influence around the upper surface atoms. Bader charge analysis shows electrons were transferred from the surface to the HM atoms, and a strong correlation between the valence electron variations and the adsorption energy was observed. HM atoms had a high electronic state overlap with the surface O atoms near the Fermi energy level, indicating that the surface O atoms, though not the topmost atoms around the surface, significantly influence HM adsorption. The above results show illite(001) preferentially adsorbed As among all four investigated HM atoms, indicating that soils containing a high proportion of illite might be more prone to As pollution.
KW - Bader charge
KW - Clay minerals
KW - Density functional theory
KW - Heavy metal pollution
KW - Surface energy
UR - http://www.scopus.com/inward/record.url?scp=85137305454&partnerID=8YFLogxK
U2 - 10.1016/j.envpol.2022.120072
DO - 10.1016/j.envpol.2022.120072
M3 - Article
C2 - 36064056
AN - SCOPUS:85137305454
SN - 0269-7491
VL - 312
JO - Environmental Pollution
JF - Environmental Pollution
M1 - 120072
ER -