Zhang Junfang, Clennell Michael B, Dewhurst David N
CSIRO Energy, 26 Dick Perry Avenue, Kensington, Western Australia 6151, Australia.
J Phys Chem B. 2023 Oct 19;127(41):8900-8915. doi: 10.1021/acs.jpcb.3c03863. Epub 2023 Oct 4.
Ion transport properties and hydrogen solubility in brine play pivotal roles in various engineering and scientific scopes including chemical, physical, geochemical, and geothermal domains. Molecular dynamics simulations were performed to obtain transport properties of NaCl in the binary HO + NaCl system using different force fields. Brine density, ion diffusivity, molar conductivity, conductivity, and hydrogen solubilities were obtained as functions of temperature and salt concentration. We compared the performance of different force fields against the experimental correlation model and developed three mathematical models. The first was the modified brine density model based on the simulated brine density over a wide range of salinity levels, and the second and third analytical mathematical models were derived for the ion diffusivity and molar conductivity as a function of salinity and temperature. The results of this study illustrated that the modified brine density model not only produced the same results of the previous model for lower salinity levels but also applied well to predict the brine density for a higher salinity level. The derived mathematical models indicated that the ion diffusivity and molar conductivity decreased linearly with salinity, and the slope and -intercept of the lines of diffusivity and molar conductivity versus temperature were third-order polynomials of temperature. The developed models provided the mechanism for the behavior of decreasing molar conductivity with increasing salinity and increasing conductivity with increasing salinity. The directions of the effect of salinity on the molar conductivity and conductivity were opposite. The molar conductivity increased with a decreasing salinity level. However, the conductivity increased with increasing salinity, as the contribution of the ion concentration or salinity level to conductivity dominated over that of the ion movement.
离子在盐水中的传输特性和氢溶解度在包括化学、物理、地球化学和地热领域在内的各种工程和科学领域中起着关键作用。利用不同的力场进行了分子动力学模拟，以获得二元HO + NaCl系统中NaCl的传输特性。获得了盐水密度、离子扩散率、摩尔电导率、电导率和氢溶解度随温度和盐浓度的变化关系。我们将不同力场的性能与实验关联模型进行了比较，并开发了三个数学模型。第一个是基于在广泛盐度水平下模拟的盐水密度的修正盐水密度模型，第二个和第三个解析数学模型是针对离子扩散率和摩尔电导率作为盐度和温度的函数而推导出来的。本研究结果表明，修正后的盐水密度模型不仅在较低盐度水平下产生了与先前模型相同的结果，而且在预测较高盐度水平下的盐水密度方面也应用良好。推导的数学模型表明，离子扩散率和摩尔电导率随盐度呈线性下降，扩散率和摩尔电导率与温度关系曲线的斜率和截距是温度的三阶多项式。所开发的模型提供了摩尔电导率随盐度增加而降低以及电导率随盐度增加而增加的行为机制。盐度对摩尔电导率和电导率的影响方向相反。摩尔电导率随盐度水平降低而增加。然而，电导率随盐度增加而增加，因为离子浓度或盐度水平对电导率的贡献超过了离子移动的贡献。
