Enriquez-Victorero Carlos, Hernández-Valdés Daniel, Montero-Alejo Ana Lilian, Durimel Axelle, Gaspard Sarra, Jáuregui-Haza Ulises
Instituto Superior de Tecnología y Ciencias Aplicadas, La Habana, A.P. 6163, Cuba.
Laboratorio de Química Computacional y Teórica, Facultad de Química, Universidad de La Habana, 10400 La Habana, Cuba.
J Mol Graph Model. 2014 Jun;51:137-48. doi: 10.1016/j.jmgm.2014.05.004. Epub 2014 May 27.
Activated carbon (AC) is employed in drinking water purification without almost any knowledge about the adsorption mechanism of persistent organic pollutants (POPs) onto it. Hexachlorocyclohexane (HCH) is an organochlorinated contaminant present in water and soils of banana crops production zones of the Caribbean. The most relevant isomers of HCH are γ-HCH and β-HCH, both with great environmental persistence. A theoretical study of the influence of AC surface groups (SGs) on HCH adsorption is done in order to help to understand the process and may lead to improve the AC selection process. A simplified AC model consisting of naphthalene with a functional group was used to assess the influence of SGs over the adsorption process. The Multiple Minima Hypersurface (MMH) methodology was employed to study γ-HCH and β-HCH interactions with different AC SGs (hydroxyl and carboxyl) under different hydration and pH conditions. The results obtained showed that association of HCH with SGs preferentially occurs between the axial protons of HCH and SG's oxygen atom, and the most favorable interactions occurring with charged SGs. An increase in carboxylic SGs content is proposed to enhance HCH adsorption onto AC under neutral pH conditions. Finally, this work presents an inexpensive computer aided methodology for preselecting activated carbon SGs content for the removal of a given compound.
活性炭（AC）被用于饮用水净化，但人们对持久性有机污染物（POPs）在其上的吸附机制几乎一无所知。六氯环己烷（HCH）是加勒比地区香蕉种植区水体和土壤中存在的一种有机氯污染物。HCH最相关的异构体是γ-HCH和β-HCH，二者都具有很强的环境持久性。开展了一项关于AC表面基团（SGs）对HCH吸附影响的理论研究，以帮助理解该过程，并可能有助于改进AC的选择过程。使用一个由带有官能团的萘组成的简化AC模型来评估SGs对吸附过程的影响。采用多极小超曲面（MMH）方法研究了在不同水合作用和pH条件下，γ-HCH和β-HCH与不同AC SGs（羟基和羧基）之间的相互作用。所得结果表明，HCH与SGs的缔合优先发生在HCH的轴向质子与SGs的氧原子之间，且与带电SGs的相互作用最为有利。有人提出，增加羧基SGs的含量可增强中性pH条件下HCH在AC上的吸附。最后，这项工作提出了一种廉价的计算机辅助方法，用于预先选择用于去除特定化合物的活性炭SGs含量。
