CO2 utilization for the waterless dyeing: Characterization and properties of Disperse Red 167 in supercritical fluid

Abstract

The physico-chemical behavior of disperse dye is the crucial point and basis for utilization CO2 in supercritical state as an environmentally friendly waterless dyeing medium, which has triggered widespread concern. In the present work, the physico-chemical behavior of Disperse Red 167 was investigated in supercritical CO2, for the first time. Scanning electron microscopy results show that the melting of Disperse Red 167 was observed with CO2 temperature increasing from 120 °C to 160 °C. Fourier transform infrared spectrometry spectra reveal that the slight shifts and differences in the intensities of the characteristic bands of Disperse Red 167 was presented before and after supercritical CO2 treatment. XRD and TG analysis indicate that crystal form of Disperse Red 167 transformed from β-type to ɑ-type due to the dissolution and melting recrystallization, and the thermal decomposition temperatures were shifted to a lower temperature when the CO2 temperature was higher than 120 °C. Moreover, dyeing experiments with the recycled Disperse Red 167 samples present similar colorimetric values and colorfastness properties to original dye. Therefore, all the investigations further offer the evidence that the melting recrystallization of disperse dyes occurred under higher temperature condition in supercritical CO2, which confirms the recycling performance of disperse dye, and also provides the feasibility for thermosol dyeing in supercritical CO2.