Apparent molar volumes of isoprene and limonene in dense-phase CO2

Abstract

Apparent molar volumes were calculated from measured density differences (δΔρ = 0.01 – 2.90 kg m⁻³, depending on compressibility) for subsaturated isoprene and limonene in CO₂ from T = 298 – 313 K and p = 8 – 13 MPa and used to fit a fluctuation solution theory equation with RMSD values of 58.5 and 177.8 cm³ mol⁻¹, respectively. Apparent molar volume minima at supercritical temperatures were correlated to a compressibility Widom line. Literature vapour-liquid-equilibrium and solubility data were compared to values calculated using fluctuation solution theory equations. The fluctuation solution theory fit to apparent molar volumes calculated literature bubble points (AARD = 0.0031 – 0.0371) and solubility data (AARD 0.6991). Krichevskii parameters for each solute were compared to literature for other similar solutes. Fluctuation solution theory was deemed a good model to calculate the properties of dilute terpenes in CO₂, especially in the near-critical region.