Determination and modelling of solubility of o-aminobenzamide and its mixture with o-nitrobenzoic acid in supercritical carbon dioxide

Abstract To research functional group effect on the solubility of o -aminobenzamide ( o -AB) and o -nitrobenzoic acid ( o -NBA) for each other, solubility of o -AB and its mixture with o -NBA in supercritical carbon dioxide (SCCO 2 ) was measured with dynamic method at temperatures ranging from 308 to 328 K and pressures ranging from 10.0 to 21.0 MPa. Then solubility of o -AB and o -NBA was correlated with four commonly used expanded liquid models. In addition, 2365 solubility data of 90 kinds of solid solute, coupled with solubility of o -AB and o -NBA in this work (2425 data points in total), were used to compare the correlation accuracy of the four expanded liquid models, and the best correlation accuracy was obtained by δ 2  ∼  δ 1 / v 1 model. To evaluate the effect of heat capacity terms that is usually ignored during the derivational process of expanded liquid models, a new expanded liquid method (M- δ 1 / v 1 model) was proposed based on δ 2  ∼  δ 1 / v 1 model and tested by the above mentioned 2425 groups of solubility data. The correlated results showed that M- δ 1 / v 1 model achieved the minimum average absolute relative deviation (AARD, %) 9.72% among the five models of 30.05%, 14.22%, 13.91%, 15.07% for δ 2  ∼  ρ , δ 2  ∼  ρ d , δ 2  ∼  δ 1 / v 1 , and β 12  ∼  ρ 2 models, respectively. Furthermore, the result of statistical tests of δ 2  ∼  δ 1 / v 1 and M- δ 1 / v 1 models indicated that the best correlation accuracy of M- δ 1 / v 1 model could be attributed to the additional consideration of the heat capacity terms, rather than the more adjustable parameters.