A short-cut method to predict the solubilities of solids in supercritical carbon dioxide

A simple empirical method is proposed to evaluate the solubilities of polar and non-polar solids in supercritical carbon dioxide. The method requires as input parameters only two easily obtained properties of pure solids: the molecular weight, M, and the melting temperature, tm. From these data a pseudo-sublimation enthalpy is derived for several classes of compounds grouped according to their polarity degree and M and tm values. The enthalpic datum is inserted in a slightly modified form of a well known relation which links the enhancement factor, E, to the density of supercritical gas. Two empirical parameters embodied in the resulting equation, in turn, are correlated with M and tm for each class of compounds. The density of carbon dioxide is calculated according to the Vetere EOS from the experimental data of pressure and temperature. The method was applied to several compounds which range from high molecular weight hydrocarbons to molecules of biological interest, like vitamins and anti-inflammatory drugs.