A recirculating equilibrium procedure for determining organic compound solubility in supercritical fluids. Anthracene in carbon dioxide

An instrumental recirculation technique was developed to measure the solubility of organic compounds and thus their potential extractability, in supercritical fluids over the pressure range of 80-500 bar. Anthracene, whose solubility is well defined, was chosen as a model compound to be used in evaluating the recirculation technique. Its solubility in supercritical carbon dioxide was measured at 40, 50, and 60 degrees C using an off-line spectroscopic technique. The solubility data were found to have good precision and to agree with published results. Anthracene solubility increased with pressure but was more enhanced by higher temperature. An upper crossover pressure of the isotherms due to retrograde vaporization that agreed with theory was found at 142.2 bar.