Sustainable ultrasound-assisted ultralow liquor ratio dyeing of cotton fabric with natural turmeric dye

Natural dyes are environmentally friendly and have become important alternatives to synthetic dyes in some dyeing products. Therefore, better extraction and dyeing techniques need to be developed for the dyeing process of natural dyes. In this work, cotton fabric was dyed using turmeric extraction solution under an ultralow liquor ratio (materials to liquor ratio of 1:5) and ultrasonic-assisted conditions. Dye extraction using different dispersants and pH values has been investigated and three-factor-three–level Box–Behnken design was employed to explore the dyeing conditions. It was found that sodium dodecyl sulfate systems and ultrasonic waves can effective improve the dyeing depth under neutral condition. The K/ S value can reach 2.53 with ultrasonic power of 200 W, dyeing time of 30 min and temperature of 40℃. Scanning electron microscope images showed that the application of ultrasound did not cause obvious fiber damage. The developed technique could be used in the textile industry to make dyeing cotton fibers with natural dyes more sustainable than it is at present.