Statistical Optimisation of Dyeing Conditions for Colouration of Soya-Bean Based Bio-Cationized Cotton with Catechu

This present study focuses on the statistical optimisation of dyeing parameters for eco-friendly dyeing of waste soybean seeds-based bio-cationized cotton using Catechu (an anionic natural dye) and potash-alum (fitkari) as an eco-friendly mineral-based bio-mordant. Cotton cellulose was modified using acid-hydrolysed extracts from de-oiled waste soybean seeds to enhance dye affinity, enabling salt-free dyeing. Six independent input dyeing process variables were optimised considering mordant concentration, dye concentration, pH of the dye bath, material-to-liquor ratio (MLR), dyeing time, and dyeing temperature. Initial experiments showed that an optimum K/S value of 6.75 and ∆E value of 10.12 can be achieved using 10% bio-cationized cotton, pre-mordanted with 10% potash alum and dyed with 30% catechu. Further statistical optimisation and ANOVA analysis revealed improved results of K/S value up to 6.95 and ΔE value of 10.22 under optimised conditions, i.e. dye bath pH 5, 60 minutes dyeing time, 70°C dyeing temperature, and an MLR of 1:20, without the use of salt.