Alkhatib Ismail I I, Pereira Luís M C, Torne Jordi, Vega Lourdes F
Chemical Engineering Department, Khalifa University of Science and Technology, P.O. Box 127788, Abu Dhabi, United Arab Emirates.
Phys Chem Chem Phys. 2020 Jun 21;22(23):13171-13191. doi: 10.1039/d0cp00846j. Epub 2020 Jun 4.
The consideration of polar interactions is of vital importance for the development of predictive and accurate thermodynamic models for polar fluids, as they govern most of their thermodynamic properties, making them highly non-ideal fluids. We present here for the first time the extension of the soft-SAFT equation of state (EoS), named polar soft-SAFT, to explicitly model intermolecular polar interactions (dipolar and quadrupolar), using the approach of Jog and Chapman (P. K. Jog and W. G. Chapman, Mol. Phys., 1999, 97(3), 307-319). The theory is first validated using molecular simulation data for a wide range of polar model systems including Stockmayer fluids, LJ dimers with dipole, and quadrupolar LJ fluids, for a wide range of thermophysical properties such as liquid density, vapour pressure, surface tension and heat capacities. Excellent agreement between polar soft-SAFT and simulation data has been obtained for all examined fluids and properties for systems exhibiting low to intermediate polar strength, while the agreement deteriorates at very high polar strengths. Once validated with simulations, the equation has been applied to calculate vapour-liquid equilibria (VLE), surface tension and second-order derivative properties of systems such as 2-ketone and methane chloride families as showcases for dipolar fluids and the benzene family for quadrupolar fluids, finding very good agreement with experimental data. In order to preserve the robustness of the model, the experimental value of the dipole or quadrupole was used in these calculations, while the additional parameter for the polar fluids was set a priori rather than included in the fitting procedure. The excellent agreement found with simulations and experiments empowers the soft-SAFT equation with new capabilities for the development of robust and accurate molecular models of polar fluids of industrial relevance.
考虑极性相互作用对于开发用于极性流体的预测性和精确热力学模型至关重要，因为它们决定了这些流体的大部分热力学性质，使其成为高度非理想流体。我们首次在此展示了软统计缔合流体理论（SAFT）状态方程的扩展，即极性软SAFT，它使用Jog和Chapman的方法（P. K. Jog和W. G. Chapman，《分子物理学》，1999年，97(3)，307 - 319）来明确模拟分子间的极性相互作用（偶极和四极）。该理论首先使用包括斯托克迈耶流体、带偶极的LJ二聚体以及四极LJ流体等多种极性模型系统的分子模拟数据进行验证，涉及多种热物理性质，如液体密度、蒸气压、表面张力和热容。对于低至中等极性强度的系统所考察的所有流体和性质，极性软SAFT与模拟数据都取得了极好的一致性，而在极高极性强度下一致性会变差。一旦通过模拟验证，该方程已被应用于计算诸如2 - 酮和氯甲烷家族等偶极流体系统以及苯家族等四极流体系统的气液平衡（VLE）、表面张力和二阶导数性质，与实验数据取得了很好的一致性。为了保持模型的稳健性，在这些计算中使用了偶极或四极的实验值，而极性流体的附加参数是预先设定的，而非包含在拟合过程中。与模拟和实验结果取得的极好一致性赋予了软SAFT方程新的能力，可用于开发具有工业相关性的极性流体的稳健且精确的分子模型。
