In this study, we present a new equation of state for electrolyte solutions, integrating the statistical associating fluid theory for variable range interactions utilizing the generic Mie form and binding Debye–Hückel theories. This equation of state underscores the pivotal role of ion–ion association in determining the properties of electrolyte solutions. We propose a unified framework that simultaneously examines the thermodynamic properties of electrolyte solutions and their electrical conductivity, given the profound impact of ion pairing on this transport property. Using this equation of state, we predict the liquid density, mean ionic activity coefficient, and osmotic coefficient for binary NaCl, Na2SO4, and MgSO4 aqueous solutions at 298.15 K. Additionally, we evaluate the molar conductivity of these systems by considering the fraction of free ions derived from our equation of state in conjunction with two advanced electrical conductivity models. Our results reveal that, while ion–ion association has a minimal influence on the modification of the predicted properties of sodium chloride solutions, their impact on sodium and magnesium sulfate solutions is considerably more noticeable.

中文翻译：

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电解质溶液中离子-离子缔合的理论与实践研究

在这项研究中，我们提出了一种新的电解质溶液状态方程，利用通用米氏形式和结合的德拜-休克尔理论，整合了可变范围相互作用的统计关联流体理论。该状态方程强调了离子-离子缔合在确定电解质溶液性质中的关键作用。考虑到离子对对这种传输特性的深远影响，我们提出了一个统一的框架，可以同时检查电解质溶液的热力学特性及其电导率。使用该状态方程，我们预测了 298.15 K 下 NaCl、Na2SO4 和 MgSO4 二元水溶液的液体密度、平均离子活度系数和渗透系数。此外，我们通过考虑游离态的分数来评估这些系统的摩尔电导率从我们的状态方程与两个先进的电导率模型相结合得出的离子。我们的结果表明，虽然离子-离子缔合对氯化钠溶液的预测性质的改变影响很小，但它们对硫酸钠和硫酸镁溶液的影响要明显得多。