Tunega Daniel, Gerzabek Martin H, Böhm Leonard
Institute for Soil Research, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences Vienna, Vienna, Austria.
Institute of Soil Science and Soil Conservation, Research Centre for BioSystems, Land Use and Nutrition (iFZ), Justus Liebig University Giessen, Giessen, Germany.
J Comput Chem. 2025 Jan 30;46(3):e70042. doi: 10.1002/jcc.70042.
Halogenated benzenes (HBs) are hydrophobic organic chemicals belonging to persistent organic pollutants. Owing to their persistence, they represent a serious problem in environmental contamination, specifically of soils and sediments. One of the most important physical processes determining the fate of HBs in soils is adsorption to main soil components such as soil organic matter and soil minerals. Smectites, layered clay minerals of the 2:1 type, are common minerals in clay-rich soils, of which montmorillonite (Mt) is a typical representative. This work focuses on a systematic modeling study of the adsorption mechanism of selected HBs interacting with the basal (001) surface, which is the dominant surface of Mt particles. The HB···Mt interactions were studied by means of a quantum chemical approach based on the density functional theory method. HBs were represented by five molecules, particularly CF, CClF, CCl, CBrCl, and CBr. In mixed HBs (CClF and CBrCl) Cl atoms are in 1,3,5 or rather 2,4,6 positions. The effect of a different cation type on adsorption was investigated for M/M-Mt models with cations from alkali group (M: Li, K, Na, Rb, Cs) and alkaline earth metal group (M: Mg, Ca, Sr., Ba). The calculations were also performed on the gas phase HB···M/M complexes for comparison. Adsorption energies and distances of the main HB molecular plane from the Mt surface were calculated as a measure of the adsorption strength. The results showed that the strongest HB adsorption is for the Na-Mt and Ca-Mt surfaces. The strongest affinity was observed for hexabromobenzene, while the weakest adsorption was found for hexafluorobenzene. The decomposition of the adsorption energy showed that its dominant component is dispersion energy and less important is the cation-π interaction. The calculated adsorption energies showed a good correlation with experimentally determined log K values.
卤代苯（HBs）是属于持久性有机污染物的疏水性有机化学品。由于它们的持久性，它们在环境污染尤其是土壤和沉积物污染方面构成了严重问题。决定HBs在土壤中归宿的最重要物理过程之一是吸附到主要土壤成分上，如土壤有机质和土壤矿物质。蒙脱石是2:1型的层状粘土矿物，是富含粘土的土壤中的常见矿物，其中蒙脱石（Mt）是典型代表。这项工作重点是对选定的HBs与Mt颗粒的主要表面（001）基面相互作用的吸附机制进行系统的建模研究。通过基于密度泛函理论方法的量子化学方法研究了HB···Mt相互作用。用五个分子代表HBs，特别是CF、CClF、CCl、CBrCl和CBr。在混合HBs（CClF和CBrCl）中，Cl原子处于1,3,5或更确切地说是2,4,6位置。对于具有碱金属族（M：Li、K、Na、Rb、Cs）和碱土金属族（M：Mg、Ca、Sr、Ba）阳离子的M/M-Mt模型，研究了不同阳离子类型对吸附的影响。还对气相HB···M/M配合物进行了计算以作比较。计算了吸附能以及主要HB分子平面到Mt表面的距离，以此作为吸附强度的一种度量。结果表明，对于Na-Mt和Ca-Mt表面，HB的吸附最强。对六溴苯的亲和力最强，而对六氟苯的吸附最弱。吸附能的分解表明，其主要成分是色散能，阳离子-π相互作用不太重要。计算得到的吸附能与实验测定的log K值具有良好的相关性。
