Dyeing of the woolen knitwear with acid dye

Abstract

The process of woolen knitwear dyeing using acid dye is investigated in this paper. Wool, as a natural protein fiber, is quite costly to produce and process, and thus it is crucial to ensure its economic viability and meet consumer demands. Acid dyes are a popular choice for woolen knitwear dyeing because of their strong coloring properties and ability to bind to the protein fibers in wool. They are usually strongly dyed compounds whose colouring depends on the molecular structure. A woolen knitwear made of 100% extra fine merino wool was used. In this specific study, was used a brand of acid dye called Supramin Blau GW and tested different concentrations and dyeing times to see how they affected the final color of the wool fibers. The dye concentrations were 100, 200, 300, 400, and 500 mg/l. The dyeing time were 5, 10, 15, 25, 35 and 45 minutes. The aqueous dye solution had an electrolyte concentration of 2 g/l of sodium acetate and acetic acid for a pH of 5, while the dyeing temperature was 98?C. The results showed that initial dye concentration and dyeing time increased, resulting in a corresponding increase in the degree of dye exaustion on the wool fibers. A longer dyeing time resulted in a higher degree of dye exhaustion. The Freundlich's and Langmuir's models were used to describe the adsorption process, which gives the relationship between the amount of dye adsorbed on the woolen knitwear and the concentration of dye in the solution. Freundlich's model was better that Langmuir's model for describing the adsorption process because there was very little scatter around the ideal curve and functional straight lines covered most points well. Overall, this study highlights the importance of understanding the factors that influence the dyeing process of woolen knitwear with acid dyes, as it can help ensure that the final product is economically sustainability and meets consumer demands.