High-pressure phase behavior of the carbon dioxide-trifluoropropylisobutyl polyhedral oligomeric silsesquioxane binary system

Date

2025-05-01

Author

Ertaş, Alican
Dilek Hacıhabiboğlu, Çerağ

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The solubility of a bifunctional polyhedral oligomeric silsesquioxane, trifluoropropylisobutyl (TFIB) POSS, in supercritical carbon dioxide (scCO2) was investigated. In the temperature and pressure ranges of 308 K to 323 K and 8.8 MPa to 14.5 MPa, respectively, TFIB POSS is soluble in scCO2 up to 2.0 × 10−2 by weight fraction corresponding to 1.0 × 10−3 by mole fraction, which is between the solubility of its monofunctional counterparts, octaisobutyl POSS and octatrifluoropropyl POSS. The study includes the modeling of the TFIB POSS-CO2 binary system phase equilibrium with the density-based semi-empirical equations and Peng Robinson+COSMO segment activity coefficient (PR+COSMOSAC) equation of state (EOS). The prediction of the equation of state has been improved for the cage-structured molecule by introducing new electrostatic and dispersion contributions. While the density-based relations provide better fits to the solubility isotherms, the main advantage of the EOS is its applicability for a priori phase equilibrium predictions for the CO2-POSS systems in the absence of the solute critical properties.

Subject Keywords

DFT, Gibbs free energy, POSS, PR+COSMOSAC EOS, Solubility

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https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85216925939&origin=inward
https://hdl.handle.net/11511/113658

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Department of Chemical Engineering, Article