Experimental measurements and theoretical modeling of high-pressure mass densities and interfacial tensions of carbon dioxide + n-heptane + toluene and its carbon dioxide binary systems
Experimental measurements and theoretical modeling of high-pressure mass densities and interfacial tensions of carbon dioxide + n-heptane + toluene and its carbon dioxide binary systems
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DOI：
10.1016/j.fuel.2018.04.057
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发表时间：
2018-09
期刊：
影响因子：
7.4
通讯作者：
Constanza Cumicheo;M. Cartes;E. A. Müller;A. Mejía
中科院分区：
文献类型：
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作者：
Constanza Cumicheo;M. Cartes;E. A. Müller;A. Mejía
本文报道了在0.1-8 MPa压力范围内，不同甲苯体积分数（0，25，50，75，100%v/v）的CO_2-正庚烷（正庚烷+甲苯）混合物体系等温（344.15K）质量密度和界面张力的实验测定和理论预测。测量是在一个高压装置上进行的，该装置包括一个振动管密度计和一个悬滴张力计。质量密度、相平衡和界面性质的理论建模（即，界面张力和界面浓度分布）是通过采用平方梯度理论，使用统计缔合流体理论状态方程的扩展来进行的，该状态方程考虑了环流体。体相平衡密度和界面张力的实验结果与理论预测吻合得很好。尽管在本文探索的条件下没有这些混合物的先前实验数据，但结果遵循从其他条件下的实验数据观察到的相同趋势。实验和模拟相结合的方法提供了一条在可接受的统计偏差范围内同时预测相平衡和界面性质的途径，对于本文所研究的体系和条件，我们观察到混合物的相平衡显示非共沸汽液平衡，与理想行为有正偏差。质量堆密度的行为一般，而界面张力降低的压力或液体摩尔分数的CO2增加和/或甲苯/庚烷的比例降低。沿界面区域的界面浓度沿着表现出显着的高过量吸附的CO2，这与压力增加，它是在正庚烷比在甲苯中更大。甲苯没有表现出任何特殊的吸附活性，而正庚烷显示的表面活性，只有在很窄的范围内的情况下，CO2+（25%正庚烷+75%甲苯）混合物的低压。
Experimental determination and theoretical predictions of the isothermal (344.15 K) mass densities and interfacial tensions for the system carbon dioxide (CO2) with heptol (n-heptane + toluene) mixtures varying liquid volume fraction compositions of toluene (0, 25, 50, 75, 100% v/v) and over the pressure range 0.1–8 MPa are reported. Measurements are carried out on a high-pressure device that includes a vibrating tube densimeter and a pendant drop tensiometer. Theoretical modeling of mass densities phase equilibria and interfacial properties (i.e., interfacial tension and interfacial concentration profiles) are performed by employing the Square Gradient Theory using an extension of the Statistical Associating Fluid Theory equation of state that accounts for ring fluids. The experimental bulk phase equilibrium densities and interfacial tensions obtained are in very good agreement with the theoretical predictions. Although there are no previous experimental data of these mixtures at the conditions explored herein, the results follow the same trends observed from experimental data at other conditions. The combination of experimental and modeling approaches provides a route to simultaneously predict phase equilibrium and interfacial properties within acceptable statistical deviations.For the systems and conditions studied here, we observe that the phase equilibrium of the mixtures display zeotropic vapor-liquid equilibria with positive deviations from ideal behavior. The mass bulk densities behave ordinarily whereas the interfacial tensions decrease as the pressure or liquid mole fraction of CO2increases and/or the ratio toluene/heptane decreases. The interfacial concentration along the interfacial region exhibits a remarkable high excess adsorption of CO2, which increases with pressure and it is larger in n-heptane than in toluene. Toluene does not exhibit any special adsorption activity whereas n-heptane displays surface activity only at low pressure in a very narrow range for the case of CO2+ (25% n-heptane + 75% toluene) mixture.