Green Sustainable Textile Supercritical Dyeing Process Using CO2 Madder (Rubia tinctorum L.) Extract

Waterless or reduced water consumption dyeing methods based on supercritical technologies are of interest to fabric manufacturers. The study was aimed at developing a dyeing method for natural fibers, in particular linen and silk, by pressure supercritical impregnation using madder alizarin (R. tinctorum) coloring compound produced by supercritical extraction method as an ecological alternative to conventional dyeing methods. A comparative test of fabric dyeing using supercritical and conventional methods was also carried out. In these dyeing technologies, the pre-treatment process plays an important role in the color intensity. The tests were performed using fabrics without and with mordants, and the results were compared using the color analysis method. The colors of the dyed samples obtained in the supercritical technology are more in shades of carmine, and in the traditional method in duller reds. The proposed modern and ecological dyeing technology guarantees a good resistance to washing and light. Antibacterial activity tests were also performed using supercritical and ethanol extracts. Dyed fabrics play health-promoting and protective roles for their users. Linen fabrics showed antimicrobial activity and positive effects on the skin, which was more moisturized. Waterless technologies should be developed in conjunction with user and environmental impact studies.