Instituto Superior de Tecnologías y Ciencias Aplicadas, University of Havana, Havana 10400, Cuba.
Laboratoire COVACHIM M2E, EA 3592, Université des Antilles, 97110 Pointe-à-Pitre, Guadeloupe, France.
Molecules. 2021 Nov 18;26(22):6969. doi: 10.3390/molecules26226969.
The influence of nitrogen-containing surface groups (SGs) onto activated carbon (AC) over the adsorption of chlordecone (CLD) and β-hexachlorocyclohexane (β-HCH) was characterized by a molecular modelling study, considering pH (single protonated SGs) and hydration effect (up to three water molecules). The interactions of both pollutants with amines and pyridine as basic SGs of AC were studied, applying the multiple minima hypersurface (MMH) methodology and using PM7 semiempirical Hamiltonian. Representative structures from MMH were reoptimized using the M06-2X density functional theory. The quantum theory of atoms in molecules (QTAIM) was used to characterize the interaction types in order understanding the adsorption process. A favorable association of both pesticides with the amines and pyridine SGs onto AC was observed at all pH ranges, both in the absence and presence of water molecules. However, a greater association of both pollutants with the primary amine was found under an acidic pH condition. QTAIM results show that the interactions of CLD and β-HCH with the SGs onto AC are governed by Cl···C interactions of chlorine atoms of both pesticides with the graphitic surface. Electrostatic interactions (H-bonds) were observed when water molecules were added to the systems. A physisorption mechanism is suggested for CLD and β-HCH adsorption on nitrogen-containing SGs of AC.
采用分子建模研究了含氮表面基团（SGs）对活性炭（AC）吸附氯丹（CLD）和β-六氯环己烷（β-HCH）的影响，考虑了 pH（单质子化 SGs）和水合效应（最多三个水分子）。研究了两种污染物与胺和吡啶作为 AC 的碱性 SGs 的相互作用，应用多极小值超曲面（MMH）方法并使用 PM7 半经验哈密顿量。使用 M06-2X 密度泛函理论对 MMH 中的代表性结构进行了重新优化。使用原子在分子中的量子理论（QTAIM）来表征相互作用类型，以了解吸附过程。在没有和存在水分子的情况下，在所有 pH 范围内都观察到两种农药与胺和吡啶 SGs 与 AC 的有利结合。然而，在酸性 pH 条件下，发现两种污染物与伯胺的结合程度更大。QTAIM 结果表明，CLD 和β-HCH 与 AC 上 SGs 的相互作用受两种农药氯原子与石墨表面的 Cl···C 相互作用控制。当向体系中添加水分子时，观察到静电相互作用（氢键）。提出了 CLD 和β-HCH 在含氮 SGs 上的物理吸附机理。
