Molecular dynamics simulations of small halogenated organics at the air-water interface: implications in water treatment and atmospheric chemistry.
Molecular dynamics simulations of small halogenated organics at the air-water interface: implications in water treatment and atmospheric chemistry.
复制标题
空气-水界面小卤代有机物的分子动力学模拟：对水处理和大气化学的影响。
DOI：
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发表时间：
2013
影响因子：
2.9
通讯作者：
Martina Roeselová
中科院分区：
文献类型：
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作者：
A. Habartová;K. Valsaraj;Martina Roeselová
采用经典的分子动力学模拟方法，计算了氯代和溴代卤代甲烷分子从气相通过水-汽界面向水相转移的自由能分布。所研究的物种包括氯甲烷（CH 3Cl）、溴甲烷（CH 3Br）、二氯甲烷（CH 2Cl 2）、二溴甲烷（CH 2Br 2）、氯仿（CHCl 3）和溴仿（CHBr 3）。所采用的卤代甲烷力场通过按比例放大原子电荷来调节，以再现实验水合自由能。计算得到的自由能分布在水-汽界面处有一个最小值，约为12-15 kJ·mol（-1），相对于本体液体中的完全水合。这意味着卤代甲烷在每单位体积具有大表面积的系统中表现出增强的界面浓度，例如分散在水中的气泡或分散在空气中的水滴。水处理以及大气化学的影响进行了讨论。
Free energy profiles associated with transfer of chlorinated and brominated halomethane molecules from the gas phase across the water-vapor interface to the aqueous phase were calculated using classical molecular dynamics simulations. The investigated species include chloromethane (CH3Cl), bromomethane (CH3Br), dichloromethane (CH2Cl2), dibromomethane (CH2Br2), chloroform (CHCl3), and bromoform (CHBr3). The employed halomethane force field was tuned by scaling up the atomic charges to reproduce the experimental hydration free energies. The computed free energy profiles have a minimum at the water-vapor interface of about 12-15 kJ·mol(-1) relative to full hydration in the bulk liquid. This implies that the halomethanes exhibit enhanced interfacial concentrations in systems with large surface area per unit volume, such as air bubbles dispersed in water or water droplets dispersed in air. Implications for water treatment as well as for atmospheric chemistry are discussed.