Past, present and future of supercritical fluid dyeing technology – an overview

Coloration Modeling and Processing of Commodity Plastic Buttons in Supercritical Carbon Dioxide

We examined the color processing of the commodity plastic buttons made of acrylic, polyester, nylon, and casein with scCO₂. The buttons' dyeing color depth (K/S) was measured over a wide range of scCO₂ and correlated accurately with the response surface method. Moreover, we measured the solubility of C.I. Disperse Red 22 in scCO₂ to formulate a dye-sorption model for the K/S value in the color processing of the plastic buttons. Finally, the dye-sorption model for the K/S value combining the dye solubility in scCO₂ with the dye diffusion inside the buttons successfully represented the color processing of the buttons.

Waterless Dyeing and In Vitro Toxicological Properties of Biocolorants from Cortinarius sanguineus

As a part of an ongoing interest in identifying environmentally friendly alternatives to synthetic dyes and in using liquid CO2 as a waterless medium for applying the resulting colorants to textiles, our attention turned to yellow-to-red biocolorants produced by Cortinarius sanguineus fungus. The three principal target anthraquinone colorants (emodin, dermocybin, and dermorubin) were isolated from the fungal bodies using a liquid-liquid separation method and characterized using 700 MHz NMR and high-resolution mass spectral analyses. Following structure confirmations, the three colorants were examined for dyeing synthetic polyester (PET) textile fibers in supercritical CO2. We found that all three biocolorants were suitable for dyeing PET fibers using this technology, and our attention then turned to determining their toxicological properties. As emodin has shown mutagenic potential in previous studies, we concentrated our present toxicity studies on dermocybin and dermorubin. Both colorants were non-mutagenic, presented low cellular toxicity, and did not induce skin sensitization. Taken together, our results indicate that dermocybin and dermorubin possess the technical and toxicological properties needed for consideration as synthetic dye alternatives under conditions that are free of wastewater production.

Comparison of Four Density-Based Semi-Empirical Models for the Solubility of Azo Disperse Dyes in Supercritical Carbon Dioxide

Compared to traditional water dyeing, supercritical CO2 fluid waterless dyeing is more advanced concerning zero pollution, energy saving and emission reduction. The measurement of the solubility of disperse dyes in supercritical CO2 provides convenience and technological basis for the popularization and development of this technology. In the current work, the solubility of 2-[4-(2-Cyanoethylethylamino)phenyl]diazenyl-5-nitrobenzonitrile (C.I. Dispersed Red 73), 2,2′-[[4-[(4-Nitrophenyl)azo]phenyl]imino] bis-ethano (C.I. Dispersed Red 19) and 3,3′-[[4-[(4-nitrophenyl)azo]phenyl]imino] bispropiononitrile (C.I. Dispersed Orange S-RL) in supercritical CO2 was determined by flow-type supercritical fluid equipment at pressures ranging from 14 to 26 MPa and temperatures ranging from 343.15 to 403.15 K, and the solubility ranges were 1.96–19.78 × 10−6, 1.51–2.63 × 10−6 and 1.49–2.49 × 10−6 mol/mol, respectively. The increase in pressure P and temperature T has obvious effect on the increase in dye solubility. Dyes with high polarity have low solubility. Four density-based, semi-empirical models—the Chrastil, Mendez-Santiago–Teja, Kumar–Johnston and Bartle models—were employed to correlate and predict the solubility data obtained. The results showed that the relationship between the calculated and experimental values correlated best with the Kumar–Johnston model.

A Dissolution Kinetic Study of Disperse Dye in Supercritical Carbon Dioxide to Design an Efficient Supercritical Dyeing Process

The dissolution behavior of dye in supercritical carbon dioxide influences the overall mass transfer that controls a supercritical dyeing process. Increasing the dissolution rate of the dye leads to shortening of the dyeing process time and can improve the efficiency of the process. Controlling the properties of the carbon dioxide flow is a good method to improve the dissolution rate of dyes. In this study, a dissolution kinetic model was designed by quantitatively analyzing and formulating the dissolution phenomenon of dyes using an in situ UV/Vis spectrometer. Through this model, the dissolution rate was compared by varying the geometric shape of the column containing the dye and the flow rate of carbon dioxide. Moreover, the correlation equation between the Reynolds number and Sherwood number was obtained through mass transfer coefficients derived under various conditions. In order to verify the utility of this equation, it was applied to a scaled-up device and the precise result could be predicted. This study can be useful in the design of dyeing processes and make-up equipment.

Supercritical carbon dioxide as a green media in textile dyeing: A review

This review highlights the great role of supercritical carbon dioxide fluid technology in textile dyeing processes. The unequivocal physical characteristics of supercritical carbon dioxide are presented and further researched to continue the development of high efficiency, compact dyeing to save energy and water in manufacturing processes. This review also focuses on the solubility of the dyes in scCO2 as well as the application of the technology to both synthetic and natural fabrics. Some factors relating to the economics of sustainable scCO2 technology are also outlined.

Long-term natural remediation process in textile dye-polluted river sediment driven by bacterial community changes

The textile and dyeing industries are major sources of environmental water pollution all over the world. The textile wastewater effluents discharged into rivers often appear dark red-purple in color due to azo dyes, which can be transformed into carcinogenic aromatic amines. The chemicals used in dyeing are not readily degraded in nature and thus precipitate in river sediment. However, little is known about how dyeing chemicals affect river sediment and river water or how long they persist because they are difficult to monitor. To assess undetectable dyes and byproducts in river sediments, we evaluated the potential of river sediment bacteria to degrade dyes and aromatic amines. We describe the natural remediation of river sediment long-contaminated by textile dyeing effluent. After cessation of wastewater discharge, the dye-degradation potential decreased, and the aromatic amine-degradation potential increased initially and then declined over time. The changes in degradation potential were consistent with changes in the sediment bacterial community. The transition occurred on the order of years. Our data strongly suggest that dyes remained in the river sediment and that aromatic amines were produced even in transparent- and no longer colored-river water, but these chemicals were degraded by the changing sediment bacteria. Time-course monitoring of the degradation activities of key bacteria thus enables assessment of the fate of dye pollutants in river sediments.

Phase Behavior at High Pressure of the Ternary System: CO2, Ionic Liquid and Disperse Dye

High pressure phase behavior experimental data have been measured for the systems carbon dioxide (CO2) + 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim] [PF6]) and carbon dioxide (CO2) + 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim] [PF6]) + 1-amino-2-phenoxy-4-hydroxyanthraquinone (C.I. Disperse Red 60). Measurements were performed in the pressure up to 18 MPa and at the temperature (323 to 353 K). As reported in the literature, at higher concentrations of carbon dioxide the phase transition pressure increased very steeply. The experimental data for the binary and ternary systems were correlated with good agreement using the Peng-Robinson equation of state. The amount of water in phase behavior of the systems was evaluated.

Establishment of Database of Color Matching System for Supercritical CO2 Dyeing

Database of color matching system for supercritical CO2 dyeing was established and its accuracy was verified. The K/S value curves of each of the trichromatic disperse dyes (C.I. Disperse Orange 30, C.I. Disperse Red 167 and C.I. Disperse Blue 79) were parallel, which indicated that the samples suits for building database of color matching system. The color matching system was emended with calibration coefficients that were derived from data of several samples dyed with a mixtures of disperse dyes in supercritical CO2. The recipes for a given sample could be found with the calibrated color matching system in supercritical CO2 dyeing.