Measurement And Correlation Of Solubilities Of Disperse Red 343, Blue 366 And Orange 29 In Supercrtical Carbon Dioxide

Supercritical carbon dioxide dyeing has received wide attention recently, which is a green and innovative method to reduce wastewater discharge and energy consumption and need less dyeing time compared with the traditional water dyeing technology. The solubilities of dyes in supercritical carbon dioxide are necessary technological data for dyes choice and process optimization.The solubilities of disperse red 343, blue 366 and orange 29 were measured over the temperature and pressure ranges of 343.2 K to 403.2 K and 12 MPa to 28 MPa by recirculation flow method. As evidenced from the experimental results, over the entire experimental conditions, the solubilities increased with increasing pressure and increasing temperature. The transition-pressure point ( Before and behind this point, the solubility changes with temperature contrarily ) of disperse blue 366 and orange 29 was at about 12 MPa, while the red 343's didn't appear. The solubilities were also affected obviously by molecular polarity of dyes.The solubilities of the mixture of disperse red 343 and blue 366 were measured over the same experimental conditions. Compared with the binary system (disperse red 343 + CO₂ or disperse blue 366 +CO₂ ), the solubility of disperse red 343 in ternary system (disperse red 343 + disperse blue 366 +CO₂) was lower, while the disperse blue 366's was higher since entrainer effect and competition phenomenon appeared during the solving process of mixed dyes in supercritical CO₂.The experimental solubilities of disperse dyes were correlated with two types of empirical models—the Chrastil, MT models and their modified models. The correlation results of modified models were in better agreement with the experimental data than their original models. But generally speaking, the calculation precision of Chrastil equation was better than MT's. The experimental data were also correlated with dense gas model combined PR EOS and VDW mixing rules, but the result was not as well as empirical models due to parameter estimation of dyes.The partition coefficients (K_eq) of dyes between supercritical carbon dioxide and fibers were calculated. It is indicated that affinity of disperse blue 366 was higher than disperse red 343. The affinity of disperse 366 was lower in ternary system than binary system, but the disperse red 343's was close to that in binary system. It is suggested that optimal conditions of supercritical fluid dyeing were at about 20 MPa and higher temperature.