Effects of Temperature and Pressure on Interfacial Tensions of Fluid Mixtures. I. CO₂/n-Pentane Binary

Abstract

The effects of temperature and pressure on interfacial tension (IFT) of a CO2/n-pentane binary system were investigated using the pendant drop method. To ensure the accuracy and reproducibility of our results, the pendant drop method is first used to measure the IFT of fluid systems whose results are available in the literature and then the validated experimental procedure is applied to determine the IFT of the CO2/n-pentane system as functions of pressure (ranging from 0.18 to 6.07 MPa) and temperature (ranging from 296.15 to 377.55 K). Within the pressure and temperature ranges applied, IFT values varied from 0.94 to 15.2 mN/m, and it is observed that IFT decreases monotonically with isothermally increasing pressure; however, when the temperature increases isobarically, IFT decreases at low pressures but the trend reverses at higher pressures, where IFT shows greater values at higher temperatures than at lower temperatures. Modeling of the experimental IFT results using the parachor equation for the binary mixture is also discussed.

Effects of Temperature and Pressure on Interfacial Tensions of Fluid Mixtures. II. Propane/n-Pentane and Propane/n-Hexane Binaries

“…At low pressures, the IFT also decreased with isobaric increases of temperature, but at higher pressures, the trend seemed to reverse and the IFTs of higher temperatures were larger than those of lower temperatures. These findings were also observed for the binary CO 2 / n -pentane system in the first part of our study …”

“…As mentioned in the first part of our study, the density differences were needed as the input for the pendant drop analysis to determine IFT and for the parachor method to model the experimental results. To verify the accuracy of our PC-SAFT estimates of phase-density differences, the calculated density differences between liquid and vapor phases and the density of each phase for the propane/ n -pentane mixture were compared with the experimental data reported by Sage and Lacey and Kay (Figure ).…”

“…The same experimental procedures and apparatus described in Toutouni et al were used to characterize IFT of the propane/ n -pentane and propane/ n -hexane binary systems. The IFT cell is filled with propane and n -pentane (or n -hexane) to reach the target pressure while the cell is at desired temperature condition.…”

“…This paper presents the results of the second part of our study on the characterization of interfacial tension (IFT) of fluid mixtures. In the first part of the study, our objective was to verify the accuracy and reproducibility of the measurements made using a newly fabricated IFT measurement apparatus. To accomplish this goal, the IFT and vapor pressure of pure n -pentane at various temperatures were measured and compared against NIST data .…”

“…Furthermore, IFT values of CO 2 / n -pentane binary at 313 K and wide range of pressures were also measured and compared with IFT data provided by Jaeger and Eggers . The measured values are reported in the first part of this study . In this part, IFT measurements are made for binary systems of propane/ n -pentane and propane/ n -hexane at various pressure and temperature conditions using the same experimental procedures and protocols presented in the first part.…”