Wool dyeing with purple sweet potato extract by enhancing dye uptake and stability using lecithin during the mordanting process

Abstract

This study explores the use of lecithin during the mordanting stage in the natural dyeing of wool with purple sweet potato extract to enhance dye uptake. We investigate the impact of lecithin on dyeing efficiency, considering variables such as temperature, pH and dye concentration. The results demonstrate that incorporating lecithin during mordanting significantly improves dye uptake, resulting in a true purple hue with enhanced chroma in the dyed wool yarns. Dyeing under acidic conditions produced higher colour strength because of the prevalence of the red-coloured flavylium cation form of anthocyanins. Fourier Transform–infrared spectroscopy confirmed the presence of anthocyanins and their interactions with wool fibres. Additionally, colour fastness evaluations showed that the use of aluminium salts (Al3+) as a mordant played a key role in enhancing fastness properties. Light fastness was rated fair to good for both peel- and flesh-dyed wool samples. Moreover, the purple sweet potato extract demonstrated significant anti-bacterial properties, effectively inhibiting a range of bacterial strains, including both Gram-positive and Gram-negative bacteria. This study provides valuable insights into optimising natural dyeing processes and highlights the potential of lecithin in mordanting for sustainable and high-performance textile applications.