Atomistic Modeling of the Sorption Free Energy of Dioxins at Clay鈥揥ater Interfaces

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• 作者：Thomas V. Shapley ; Marco Molinari ; Runliang Zhu ; Stephen C. Parker
• 刊名：Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：November 27, 2013
• 年：2013
• 卷：117
• 期：47
• 页码：24975-24984
• 全文大小：454K
• 年卷期：v.117,no.47(November 27, 2013)
• ISSN：1932-7455

文摘

We employed dispersion corrected DFT and classical methods to identify the factors controlling the adsorption and intercalation of dioxins at water鈥揷lay mineral interfaces including sodium and organo-montmorillonites (Na-, TMA-, and HDTMA-Mont) and pyrophyllite. To evaluate the intrinsic sorptive capacity of the clay minerals, the sorption free energies of dioxins at the clay {001} surfaces were calculated, and this showed that the hydrophobicity of the surface is a factor controlling the adsorption. The intercalation of dioxins from the external solvent into the interlayer space of clays was also evaluated, showing the importance of the presence of organic cations. We found that organoclays have sufficient hydrophobicity with large organic cations, and this coupled with the swelling properties of montmorillonite ensures effective adsorption from an aqueous environment. HDTMA-Mont is shown to have these features and that the dioxins were immobilized within the long alkyl chains of the counterions.