An Investigation of Verbascum thapsus Flower as a Natural Source for Nylon 6 Fabric Dyeing

With the rise of global demand for eco-friendly alternatives and the drive toward reducing the adverse environmental impact, the exploration of new sources of natural dyes has gained significant attention. This study focused on optimizing the dyeing process of polyamide fabric using Verbascum thapsus (Mullein) flower without mordant, as well as exploring the effectiveness of biomordants as sustainable alternatives to traditional metal mordants. To investigate the effectiveness of Verbascum thapsus flowers as a textile dye, the related color coordinates as well as color strength (K/S) of the fabric samples which had been dyed were measured. The color fastness of the samples which had been dyed using different mordants was also assessed. The optimized dyeing conditions for nylon 6 dyed with Mullein extract was achieved using pH = 3, temperature = 100 degree celsius, dye concentration = 100%, material-to-liquor ratio (M:L) = 1:30, and time = 60 min. Furthermore, the effectiveness of biomordants, including pistachio hull, pomegranate peel, oak gall, and Terminalia chebula, was compared with that of traditional metallic mordants (iron (II) sulfate, zinc sulfate, copper sulfate, and aluminum potassium sulfate) in terms of enhancing the dye absorption and colorfastness. The highest K/S value was obtained in dyeing after bio-mordanting with 50% pomegranate peel. In addition, the antibacterial activity was investigated and proved in this sample. The diameter of the inhibition zone of the nylon 6 fabric bio-mordanted with 50% owf pomegranate peel and dyed with 100% Verbascum thapsus was around 25 mm for P. aeruginosa and S. aureus. It was observed that biomordants, except for Pistachio hull, improved the associated color strength for the dyed nylon 6 fabric. In contrast, metallic mordants showed a decrease of color strength. Regarding color fastness, biomordants also had positive effects on color fastness. The results indicated that biomordants could be considered as environmentally friendly alternatives to metallic mordants in the related dyeing processes. These findings can be valuable in the development of eco-friendly dyeing processes for synthetic fibers.