Combined application of plant extracts (tannic acid and baicalin) with acid dyes in the simultaneous dyeing and finishing of tussah silk for enhanced antioxidant, antibacterial and UV protective properties

Abstract

The one-step dyeing and finishing of tussah fiber have advantages of short process, high efficiency, and energy and water saving. Additionally, to upgrade the functionalities of tussah silk fiber using natural chemicals with environmental benefits can increase its applicability. In this work, the combined application of plant extracts and acid dyes was presented for simultaneously imparting colorful shades, antioxidant activity, antibacterial activity, and UV protection capability to tussah silk. The stability of tannic acid, baicalin, and their mixtures with acid dyes was first discussed, and the colors and functionalities of dyed and finished tussah silk were evaluated. Tannic acid had less effect on the colors of dyed tussah silk. C.I. Acid Blue 113 was not stable in hot baicalin solution, and its pre-heated mixture with baicalin dyed tussah silk to dull red hue rather than blue hue. The bright blue and green colors of tussah silk were obtained by dyeing with anthraquinone and triarylmethane dyes, but their hues were affected by baicalin due to the light yellow color of baicalin and the matching of colors. Tannic acid exhibited better antibacterial property than baicalin on tussah silk, while baicalin had better antioxidant and UV protection capability than tannic acid. This work demonstrates that the one-step dyeing and finishing of tussah silk with acid dyes and plant extracts are feasible. However, special attention should be paid to the color changes of individual dyes for pale dyeing.