Complexation mechanism of Pb 2+on Al-substituted hematite: A modeling study and theoretical calculation

文献类型： 外文期刊

第一作者： Liang, Yu

作者： Liang, Yu;Wei, Zhiyuan;Liang, Yu;Xiang, Yongjin;Xiong, Juan;Hou, Jingtao;Wang, Mingxia;Tan, Wenfeng;Avena, Marcelo

作者机构：

关键词： Iron oxide; Al-substitution; Interfacial reaction; CD-MUSIC model; DFT calculation

期刊名称：ENVIRONMENTAL RESEARCH （ 影响因子：8.3； 五年影响因子：8.2 ）

ISSN： 0013-9351

年卷期： 2024 年 252 卷

页码：

收录情况： SCI

摘要： Hematite nanoparticles commonly undergoes isomorphic substitution of Al 3+ in nature, while how the Alsubstitution -induced morphological change, defective structure and newly generated Al - OH sites affect the adsorption behavior of hematite for contaminants remains poorly understood. Herein, the interfacial reactions between Al -substituted hematite and Pb 2+ was investigated via CD -MUSIC modeling and DFT calculations. As the Al content increased from 0% to 9.4%, Al -substitution promoted the proportion of (001) facets and caused Fe vacancies on hematite, which increased the total active site density of hematite from 5.60 to 17.60 sites/nm 2 . The surface positive charge of hematite significantly increased from 0.096 to 0.418 C/m 2 at pH 5.0 due to the increases in site density and proton affinity (log K H ) of hematite under Al -substitution. The adsorption amount of hematite for Pb 2+ increased from 3.92 to 9.74 mmol/kg at pH 5.0 and 20 mu mol/L initial Pb 2+ concentration with increasing Al content. More Fe vacancies may lead to a weaker adsorption energy ( E ad ) of hematite for Pb 2+ , while the E ad was enhanced at higher Al content. The adsorption affinity (log K Pb ) of bidentate Pb complexes slightly increased while that of tridentate Pb complexes decreased with increasing Al content due to the presence of = AlOH -0.5 and = Fe 2 AlO - 0.5 sites. Tridentate Pb complexes were dominant species on the surface of pure hematite, while bidentate ones became more dominant with increasing Al content. The obtained model parameters and molecular scale information are of great importance for better describing and predicting the environmental fate of toxic heavy metals in terrestrial and aquatic environments.

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