Calcium chloride adsorption at liquid-liquid interfaces: A molecular dynamics simulation study
Calcium chloride adsorption at liquid-liquid interfaces: A molecular dynamics simulation study
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DOI：
10.1016/j.colsurfa.2017.05.019
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发表时间：
2017-08-20
影响因子：
5.2
通讯作者：
Ejtehadi, M. R.
中科院分区：
文献类型：
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作者：
Khiabani, N. P.;Bahramian, A.;Ejtehadi, M. R.
我们进行了分子动力学模拟（MD）来研究氯化钙（CaCl2）在正己烷-水界面上的吸附。我们还利用悬滴法测量了所选系统的界面张力 (IFT)。己烷、水和离子的直方图表明界面附近存在双电层 (EDL)。 EDL 的趋势表明，氯阴离子比钙阳离子更倾向于内在地吸附到界面上。测得的正己烷-水界面的界面宽度随着盐浓度的增加而减小。界面和本体水溶液的平均密度在垂直于界面的方向上表现出密度不均匀性。计算出的密度分布使我们能够测量每种成分的吸附值。研究发现，盐颗粒被液-液界面排斥，从而形成富含盐的本体溶液。因此，我们报告了 CaCl2 的负吸附以及随之而来的 IFT 随着盐浓度的增加而增加。与 EDL 趋势一致，钙阳离子的负吸附高于氯阴离子。
We carried out molecular dynamics simulations (MD) to investigate the adsorption of calcium chloride (CaCl2) at n-hexane-water interfaces. We also measured the interfacial tensions (IFT) of the selected systems making use of the pendant-drop method. The histograms of hexane, water, and the ions indicate an electrical double layer (EDL) near the interface. The trend of the EDL indicates that chloride anions intend to adsorb to the interface more intrinsically than calcium cations. The measured interfacial width of the n-hexane-water interfaces decreases with the salt concentration. The average densities of the interfacial and bulk aqueous solutions demonstrate density heterogeneity in the direction perpendicular to the interface. The calculated density profiles enabled us to measure the adsorption values of each component. It is found that the salt particles are repelled from the liquid-liquid interface, resulting in an enriched bulk solution with salt. We, therefore, report negative adsorptions of CaCl2 and the consequent reproduced increasing IFT with salt concentration. Consistent with the EDL trends, the negative adsorption of calcium cations is higher than that of chloride anions.