Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

The solid solubilities of 1,4-naphthoquinone and of 5-hydroxy-2-methyl-1,4-naphthoquinone (also known as plumbagin) in supercritical carbon dioxide (scCO2) were measured using a static analytical method at 308.2, 318.2, and 328.2 K, and for pressures between 9.1 and 24.3 MPa. For the three studied isotherms, experimental solubilities (in terms of solid molar fraction) ranged from 5.0*10 5 to 4.9*10 3 (for 1,4-naphthoquinone) and from 5.0*10 5 to 9.0*10 3 (for plumbagin). Experimental solubility data were correlated with three density-based models (Chrastil, Bartle, and Mendez-Santiago Teja models) and with the Peng Robinson equation-of-state (PR-EOS), together with the conventional van der Waals mixing and combining rules (one adjustable parameter, vdW1; two adjustable parameters, vdW2). Distinct experimental and estimated critical and thermophysical properties of the two solid substances were employed for the PR-EOS correlation and were discussed in terms of the quality of the obtained fitting results. Employed semiempirical density-based models led to AARD values lower than 11 %. Best results were obtained with the Chrastil model: 5.8 % and 8.5 %, for plumbagin and 1,4-naphthoquinone, respectively. Good correlation results were also achieved when using the PR-vdW2 model (with AARD values between 4.0 % and 12.2 %, for both substances and for different isotherms) despite the fact that the adequate choice of the employed critical and thermophysical properties estimation methods was critical for the obtained correlation results.