Zhu Haochen, Hu Bo
State Key Laboratory of Pollution Control and Resources Reuse, Key Laboratory of Yangtze River Water Environment, College of Environmental Science and Engineering, Tongji University, Ministry of Education, 1239 Siping Rd., Shanghai 200092, China.
Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
Membranes (Basel). 2022 Feb 14;12(2):220. doi: 10.3390/membranes12020220.
Dielectric behavior of electrolyte aqueous solutions with various concentrations in a cylindrical nanopore of MCM 41 silica has been investigated. The effect of confinement is investigated by using isothermal-isosurface-isobaric statistical ensemble, which has proved to be an effective alternative to the Grand Canonical Monte Carlo (GCMC) simulation method. Several single-salt solutions have been considered (e.g., NaCl, NaI, BaCl, MgCl) in order to investigate the effect of ion polarizability, ion size, and ion charge. The effect of salt concentration has also been addressed by considering NaCl solutions at different concentrations (i.e., 0.1 mol/L, 0.5 mol/L, and 1 mol/L). The motivation in performing this integrated set of simulations is to provide deep insight into the dielectric exclusion in NF theory that plays a significant role in separation processes. It was shown that the dielectric constant increased when ions were added to water inside the nanopore (with respect to the dielectric constant of confined pure water) unlike what was obtained in the bulk phase and this phenomenon was even more pronounced for electrolytes with divalent ions (MgCl and BaCl). Therefore, our simulations indicate opposite effects of ions on the dielectric constant of free (bulk) and nanoconfined aqueous solutions.
研究了不同浓度的电解质水溶液在MCM - 41二氧化硅圆柱形纳米孔中的介电行为。通过使用等温 - 等表面 - 等压统计系综来研究限域效应，该方法已被证明是巨正则蒙特卡罗（GCMC）模拟方法的有效替代方法。为了研究离子极化率、离子大小和离子电荷的影响，考虑了几种单盐溶液（例如，NaCl、NaI、BaCl、MgCl）。还通过考虑不同浓度（即0.1 mol/L、0.5 mol/L和1 mol/L）的NaCl溶液来探讨盐浓度的影响。进行这一系列综合模拟的目的是深入了解NF理论中的介电排斥，其在分离过程中起着重要作用。结果表明，与本体相中的情况不同，当在纳米孔内的水中添加离子时（相对于限域纯水的介电常数），介电常数会增加，并且对于含有二价离子（MgCl和BaCl）的电解质，这种现象更为明显。因此，我们的模拟表明离子对自由（本体）水溶液和纳米限域水溶液的介电常数有相反的影响。
