粘土矿物界面处构型，阴离子特异性效应，扩散以及对反离子的吸附对盐离子的影响,The Journal of Physical Chemistry C

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粘土矿物界面处构型，阴离子特异性效应，扩散以及对反离子的吸附对盐离子的影响
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2016-07-01 00:00:00 , DOI: 10.1021/acs.jpcc.6b01886
Xiong Li ₁ , Hang Li ₁ , Gang Yang ₁

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粘土矿物与盐溶液的界面相互作用无处不在，并且在广泛的领域中发挥着至关重要的作用，其中盐阳离子是重点，而阴离子通常被视为旁观者。在此，分子动力学模拟表明，各种阴离子都强烈吸附在粘土矿物的表面上，并且所产生的特定于阴离子的作用是明显的。虽然仅构建H键，阴离子形成粘土矿物稳定inner-和外球复合物，和F ^-和OH ^-会导致甚至比金属离子更稳定的络合物。潜在的特定阴离子效应遵循以下顺序：OH ^– > F ^– > Cl ^– > I ^–并显示出随着盐浓度增加而明显增强。OH ^-是特别是在相对高的浓度，从而形成簇和在八面体的AlO捕获金属离子₆的表面和接近四面体的SiO ₄的表面与除了单分散inner-和外球物种在八面体的AlO金属离子的帮助₆表面是所有阴离子相似。阴离子的扩散系数与金属离子的扩散系数处于同一数量级，并且受抗衡离子，浓度和与粘土矿物表面的距离的影响。当I ^– > Cl ^– > F ^– > OH时，内和外球阴离子的扩散系数均降低^–。阴离子的吸附会受到抗衡离子（金属离子）的影响，反之亦然。阴离子对抗衡离子吸附的影响还显示出遵循OH ^– > F ^– > Cl ^– > I ^–顺序的离子特异性效应，而OH ^–甚至可以改变抗衡离子的吸附结构和分布。

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Configuration, Anion-Specific Effects, Diffusion, and Impact on Counterions for Adsorption of Salt Anions at the Interfaces of Clay Minerals

Interfacial interactions of clay minerals with salt solutions are ubiquitous and play a crucial role in a wide range of fields, where salt cations are the focus while anions are generally regarded as spectators. Here, molecular dynamics simulations show that the various anions are strongly adsorbed on the surfaces of clay minerals, and the resulting anion-specific effects are pronounced. Although constructing only H-bonds, anions form stable inner- and outer-sphere complexes with clay minerals, and F^– and OH^– can result in even more stable complexes than metal ions. The underlying anion-specific effects abide by the sequence OH^– > F^– > Cl^– > I^– and show apparent enhancements with increase of salt concentrations. OH^– is particular at relatively high concentrations, forming clusters and capturing metal ions at octahedral AlO₆ surfaces and approaching tetrahedral SiO₄ surfaces with help of metal ions in addition to the monodispersive inner- and outer-sphere species at octahedral AlO₆ surfaces that are similar for all anions. Diffusion coefficients of anions are the same order of magnitude as those of metal ions and are affected by counterions, concentrations, and distances to the surfaces of clay minerals. Diffusion coefficients of both inner- and outer-sphere anions decrease as I^– > Cl^– > F^– > OH^–. Adsorption of anions is affected by counterions (metal ions) and vice versa. Impact of anions on the adsorption of counterions also shows ion-specific effects that follow the sequence OH^– > F^– > Cl^– > I^–, and OH^– can even alter the adsorption structure and distribution of counterions.

更新日期：2016-07-01

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