Wool dyeing using Ziziphus bark extract as a natural dye: studies on the dyeing, antibacterial, and antioxidant characteristics

Considering the growing importance of natural colorants and sustainable products, the research on application of natural dyes has been focused on new color resources, identification, and standardization of natural dyes. Hence, the extraction of natural colorants available in Ziziphus bark was performed by ultrasound technique and its application on the wool yarn to produce the antioxidant and antibacterial fibers. The optimal conditions for the extraction process were as follows: ethanol/water (1/2 v/v) as solvent, concentration of Ziziphus dye 14 g/L, pH 9, temperature 50 °C, time 30 min, and L.R ratio 50:1. Moreover, the effect of important variables for application of Ziziphus dye on the wool yarn was investigated and optimized temperature 100 °C, concentration of Ziziphus dye 50% o.w.f., time for dyeing 60 min and pH 8, and L.R 30:1. The reduction values of Gram-negative and Gram-positive bacteria on dyed samples at optimized condition were 85% and 76%, respectively. Moreover, the antioxidant property of dyed sample was 78%. The color variations on the wool yarn were produced with diverse metal mordants, and color fastness properties were measured. Ziziphus dye not only can be used as an origin for a natural dye, but also provided the antibacterial and antioxidant agent on the wool yarn, which can be a step towards the fabrication of green products.