Comparative Study of Dyeing with Cochineal Dye in Cationized Cotton with Various Proteins

The dyeing of cotton with synthetic dyes is associated with environmental and health problems, which can be overcome using natural dyes. But in natural dyeing, metal mordants are commonly used, which are also related to harmful effects on the environment and health. That is why the green process should be investigated. In this work, cotton was cationized with proteins from various sources to improve its dyeing with cochineal natural dye. Different techniques for fixing proteins in cotton were evaluated, such as direct cationization in the fabric, fixation by cross-linking, and the oxidation of cotton. All proteins evaluated and their fixation techniques resulted in greater dye adsorption than cotton without cationization. The oxidation of cotton before the application of the protein was the technique that most increased the dye adsorption in all evaluated proteins. However, the fixation of ovalbumin, keratin, and collagen proteins by cross-linking showed higher color strength after the washing process. In view of all the comparisons made, the pretreatment by fixing ovalbumin with cross-linking agent resulted in the higher values of adsorption and color strength, besides a good color uniformity. Thus, ovalbumin is a viable and eco-friendly alternative in the dyeing of cotton with cochineal.