HIGH-PRESSURE INVESTIGATIONS ON THE SOLUBILITY OF DISPERSION DYESTUFFS IN SUPERCRITICAL GASES BY VIS/NIR-SPECTROSCOPY .1. 1,4-BIS-(OCTADECYLAMINO)-9,10-ANTHRAQUINONE AND DISPERSE ORANGE IN CO2 AND N2O UP TO 180 MPA

Solubilities of 1-benzazo-4-(4'-hydroxybenzazo)-naphthale (Disperse Orange 13) and 1,4-bis-(octadecylamino)-9, 10-anthraquinone in supercritical CO2 and N2O were measured using VIS/NIR-spectroscopy over the pressure and temperature ranges of 7 to 180 MPa and 305 to 410 K. respectively. The solubility measurements were performed using VIS-spectroscopy for the concentration range of 10(-6) < c/mol dm(-3) < 10(-4), whereas the higher concentrations (10(-2) < c/mol dm(-3) < 10(-1)) of the anthraquinone dyestuff in N2O at 360 K were measured using NIR-spectroscopy, Separate measurements were also performed according to the synthetic method. For Disperse Orange 13 in CO2 some p(c) isotherms are observed to intersect. This behavior is explained in terms of a density effect, For the anthraquinone dyestuff dissolved in CO2 or N2O, maxima concentrations on the c(p) isotherms were found at about 65 MPa.