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

ABSTRACT

The solubilities of nicotinic acid and nicotinamide in supercritical CO2 with a static-analytical method were determined at temperatures (313.15, 333.15, 353.15, and 373.15) K and over the pressure range from (5 to 30) MPa. Solid-liquid phase transitions were determined with a modified capillary method in order to verify the physical state of components under pressure of gas. Solubility increased with increasing pressure for both the investigated substances. The solubility of nicotinic acid was in the range from (3.05*10-7 to 1.04*10-5) mole fraction. The solubility of nicotinamide was found to be much higher, in the order of 10-3 mole fraction. The solubility data were correlated using four different density-based models. The results showed good agreement between calculated and experimental data. Solubility measurements were also preformed for the ternary system nicotinic acid-nicotinamide-CO2 with two different mass ratios of solid components in the system (w(nicotinic acid)-w(nicotinamide) = 1:1 and 2:1) in a pressure range from (10 to 30) MPa and temperatures of (333.15 and 353.15) K. It was discovered that the composition of the mixture influences the solubilities of both components in CO2; the solubility of nicotinamide decreased 10-fold, and the solubility of nicotinic acid was up to 8 times higher than in the binary system.