Supercritical fluids dyeing

Schmidt, A. Bach, E. Schollmeyer, E. Supercritical fluid dyeing of cotton modified with 2,4,6-trichloro-l,3,5-triazine. J. Soc. Dyers Colour. 2003, 119, 31-36. 

West BL, Kazarian SG, Vincent MF, Brantley NH, Eckert CA. Supercritical fluid dyeing of PMMA films with azo-dyes. J Appl Polym Sci 1998 69 911-919. 

Bach, E., Cleve, E., and Schollmeyer (2002). Past, present and future of supercritical fluid dyeing technology— An overview,... 

Supercritical fluid CO / supercritical fluid dyeing technology... 

Studies of reversed micelles dispersed in supercritical fluids have shown their ability to solubihze hydrophihc substances, including biomolecules and dyes, opening the door to many new applications [60,61]. In particular, solutions of reversed micelles in liquid and supercritical carbon dioxide have been suggested as novel media for processes generating a minimum amount of waste and with a low energy requirement [62]. 

Supercritical fluid chromatography is the name for all chromatographic methods in which the mobile phase is supercritical under the conditions of analysis and the solvating properties of the fluid have a measurable effect on the separation. SFC has some advantages over GC and HPLC it extends the molecular weight range of GC, thermally labile compounds can be separated at lower temperatures, compounds without chromophores can be sensitively detected, and the use of open-tubular and packed columns is feasible. SFC can be employed in both the analysis of natural pigments and synthetic dyes, however it has not been frequently applied in up-to-date analytical practice. 

Supercritical fluid extraction (SFE), microwave-assisted extraction (MAE) and Soxhlet extraction under various experimental conditions were applied for spiked poly(vinyl) chloride samples. Extracted dyes were separated in an ODS column (250 X 4.6 mm i.d. particle size 5 jum) using methanol as the mobile phase. Dyes are well separated by this method as demonstrated in Fig. 3.59. The optimal parameters of the extraction methods are compiled in Table 3.23. Recoveries depended on both the type of extraction method and the chemical structure of the dye. It was found that the highest recovery can be obtained by MAE and the extraction efficacy was the lowest for Solvent red 24 [129],... 

The carcinogenic aromatic amines released from azo dyes in leather were investigated by using microwave-assisted extraction (MAE) or supercritical fluid extraction (SFE) followed by RP-HPLC. The chemical structures of dyes and aromatic amines are listed in Fig. 3.69. The flow schemes for SFE and MAE are shown in Figs 3.70. and 3.71. 

Supercritical fluids also find application in the areas of pollution prevention and remediation, and supercritical carbon dioxide is used as a replacement solvent for many hazardous solvents in both extraction and separation processes and also as a reaction medium and in materials processing. Although carbon dioxide is considered as a greenhouse gas , there is actually no net increase in the amount of the gas if it is removed from the environment, used as the solvent instead of a hazardous substance, and returned to the environment. In this way, most of the uses of supercritical carbon dioxide may be considered as environmentally friendly. Because the solubilities of oils and greases in carbon dioxide are high, it is particularly suited to the cleaning of machinery 47 and, as discussed in the literature 48, it is used as a solvent in textile dyeing operations where it is used to treat any dye-laden... 

An important innovative technique to replace water as the solvent in dyeing processes is the use of supercritical fluids, for example, supercritical CO2 for dyeing processes. Successful trials have been conducted in various scales with different fibers and full-scale production has been performed in the case of PES dyeing [62,63]. Besides the handling of high pressure equipment, the development of special dyestuff formulations is required. 

Liu JC, Ikushima Y, Shervani Z (2004) Investigation on the solubilization of organic dyes and micro-polarity in AOT water-in-C02 microemulsions with fluorinated cosurfactant by using UV-Vis spectroscopy. J Supercrit Fluids 32 97-103... 

Remarkable tuning of reaction rates has been achieved for the isomerization of several dye molecules in supercritical fluid solvents using both small pressure changes and small additions of cosolvents. Rates of the thermal cis-trans relaxation were measured spectroscopically following irradiation for three dyes in supercritical carbon dioxide and ethane, pure and with several polar and protic cosolvents. These results demonstrate the versatility of supercritical fluid solvents, both to examine reaction mechanisms and as a means to tune rates (DiUow et al., 1998). 

Remarkable tuning of reaction rates has been achieved for the isomerization of several dye molecules in supercritical fluid solvents (DUlow et al., 1998). 

Dyeing. Supercritical fluid can be used to provide a water and solvent-free method of textile dyeing. Fluoro-modified dyestuffs have been developed in order to provide improved light-fastness etc. and are readily available. It might be interesting to research die supercritical fluid solubility of these products.23-27... 

Dyeing with supercritical fluids Cell structure treatment with supercritical fluids (e.g., C02) 80 - 300 dyeing of fabrics tobacco impregnation... 

Paprika can be extracted to recover carotenoids, not only with CO2 but also with other gases. For example, by using ethane or ethylene, better results were obtained for the yield, extraction time, and quality of product. The solubilities of carotenoids are better in these gases, which is why the consumption of solvent and the extraction time were reduced. Practically water-free dye-concentrate was recovered by supercritical fluid ethane (under the conditions extraction 250 bar, 45°C separation 46 bar, 45 °C). The separation of pungent substances (capsaicinoids, free fatty acids) from the pigments can be carried out effectively in a continuous, counter-current extraction column with a large number of theoretical plates. 

By utilizing the rapid expansion of supercritical solutions, small-size particles can be produced from materials which are soluble in supercritical solvents. In this process, a solid is dissolved in a pressurized supercritical fluid and the solution is rapidly expanded to some lower pressure level which causes the solid to precipitate. This concept has been demonstrated for a wide variety of materials including polymers, dyes, pharmaceuticals and inorganic substances. 

Flotation - [AMINES - FATTY AMINES] (Vol 2) - [FLOTATION] (Vol 11) - [FOAMS] (Vol 11) - [METALLURGY-SURVEY] (Vol 16) -dye water effluent treatment [DYES, ENVIRONMENTAL CHEMISTRY] (Vol 8) -isopropyl xanthates for [PROPYL ALCOHOLS - ISOPROPYL ALCOHOL] (Vol 20) -of lead ore [LEAD] (Vol 15) -formica [MICA] (Vol 16) -m paper recycling [RECYCLING - PAPER] (Vol 21) -ofpotassium chlonde [POTASSIUM COMPOUNDS] (Vol 19) -silicates for [SILICON COMPOUNDS - SYNTHETIC INORGANIC SILICATES] (Vol 22) -use of copper composition [COPPER COMPOUNDS] (Vol 7) -usmgSCFs [SUPERCRITICAL FLUIDS] (Vol 23)... 

Use of Solvatochromic Dyes To Correlate Mobile Phase Solvent Strength to Chromatographic Retention in Supercritical Fluid Chromatography... 

Nile Red was recently introduced as a solvatochromic dye for studying supercritical fluids (10). Although not ideal, Nile Red does dissolve in both nonpolar and polar fluids and does not lose its color in the presence of acids, like some previously used dyes. Major criticisms of Nile Red include the fact that it measures several different aspects of "polarity" simultaneously (polarizability and acidity (15)) yet it is insensitive to bases (10). However, in chromatography other single dimension polarity scales, like P, are routinely used. Measurements with Nile Red and other dyes indicate that the solvent strength of binary supercritical fluids is often a non-linear function of composition (10-14). For example, small... 

Solvatochromic data, specifically absorption or transition energies (E s), have been obtained for the dye phenol blue in supercritical fluids as a function of both temperature and pressure. These data will be used to compare the "solvent strength" of these fluids with liquid solvents. He will use the terms "solvent strength" and "Et" synonymously in this paper such that they include the magnitude of the polarizability/volume as well as the dipole moment. The "solvent strength" has been characterized by the spectroscopic solvatochromic parameter, E, for numerous liquid solvents (9 JU, J7,JJ3). 

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