Bubble point pressures and densities of hexamethyldisiloxane–carbon dioxide binary mixture using a constant volume view cell

The phase behavior of hexamethyldisiloxane (HMDS)–carbon dioxide (CO2) binary mixture was investigated using a constant volume view cell. The accuracy of the measurement technique was inspected against the bubble point pressure data in the literature for ethanol (C2H5OH)–carbon dioxide (CO2) binary mixture. The bubble point pressures for C2H5OH–CO2 agreed well with the literature values. The bubble point pressures of HMDS–CO2 binary mixture were determined at five different temperatures (T = 298.2 K, 308.2 K, 313.2 K, 323.2 K, 333.2 K) and at various compositions. The bubble point pressures increased with increasing temperature and CO2 mole fraction in the binary mixture. The phase behavior of the binary mixture was modeled using the Peng–Robinson Stryjek–Vera equation of state (PRSVEoS). The binary interaction parameters were regressed from experimental bubble point pressures at each temperature and were found to exhibit a linear dependency on temperature. The HMDS–CO2 binary mixture was also found to exhibit Type II phase behavior. Additionally, P–T–ρ measurements for the same binary system were conducted and excess molar volumes were calculated.

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► Bubble point pressures of hexamethyldisiloxane–carbon dioxide binary mixture were measured.
► The accuracy of a constant volume view cell for measuring bubble point pressures was evaluated.
► The Peng–Robinson Stryjek–Vera equation of state was used to model the phase behavior.
► HMDS could be a better solvent than Selexol due to its lower bubble point pressures with CO2.