Natural dyeing of wool with henna and yarrow enhanced by plasma treatment and optimized with response surface methodology

In this study, response surface methodology was employed for optimization of natural dyeing of wool with henna leaves and yarrow flowers. As natural dyes have generally low affinity towards textile fibers and need considerable amounts of metal mordants to be absorbed satisfactorily, plasma treatment was used as an environmentally friendly pretreatment to enhance the dyeability and lower the amount of mordant needed. The results showed that the color value of the samples increased by increasing the plasma treatment power, dyebath temperature, and alum mordant concentration. However, the color value was higher at lower pH values. ATR-FTIR, SEM, and AFM investigations confirmed the significant surface chemical and topographical changes of the fibers. Plasma treatment can be considered as an alternative of wet chemical treatments for surface modification of wool to improve its dyeability and reduce the need for potentially toxic metallic mordants.