Valorization of Natural Dye Extracted from Date Palm Pits (Phoenix dactylifera) for Ecofriendly Dyeing of Bicomponent Polyester Filaments

Bicomponent (PET/PTT) filaments have excellent elastic recovery, elasticity, thermal comfort, etc., which make them appropriate for use in sports clothing. As they are dyed with chemical dyestuffs, it could cause a great harm to human health. In this context, this paper investigates the possibility of dyeing PET/PTT with a natural colorant obtained from date palm pits (DPP). This natural dye showed, in our previous studies, very good results for dyeing cotton. The extracted solution was characterized and its chemical constitution, antioxidant activity, and GC/MS study were investigated and discussed. Knitted fabrics consisting of 100% bicomponent (PET/PTT) filaments were used for dyeing with the aqueous extract. The influence of the dyeing parameters on the value of the color yield ( \(\sum \left(\frac{K}{S}\right)\) $\sum \left(\frac{K}{S}\right)$ ) and the colorimetric \(\left({L}^{*};{a}^{*};{b}^{*};{C}^{*};h\right)\) $\left(L^{\ast },;,a^{\ast },;,b^{\ast },;,C^{\ast },;,h\right)$ coordinates was evaluated and analyzed. The studied parameters were the dyebath pH, temperature, and the duration of dyeing. The color fastnesses of dyed fabrics were also analyzed and improved using bio-based adjuvants. The obtained results indicated that the optimum dyeing conditions (pH = 5, temperature = 100 °C, duration = 60 min) led to the best value of color yield. Moreover, excellent wash and sweat fastness values (in the range of 4–5) were found. The GC/MS study of acetonic extract powder of date palm pits revealed the phenolic groups responsible for the coloring of the polyester fibers and confirmed the presence of certain compounds having antifungal, antibacterial, antioxidant, and anticancer activities.