Investigation of the effects of reactive dyes functionality on dyeing behaviors of fabrics and the environment

Abstract

Reactive dyes are most commonly used for dyeing of cotton which is the most preferred natural fiber. Although these dyes have many advantages such as wide color gamut, bright colors and being able to be applied in different ways, they have some disadvantages such as losing their dye properties by hydrolysis, remaining hydrolyzate in the liquor and on the fiber surface, and requiring long and costly washing processes to remove hydrolyzates. Various dyes modifications have been conducted within the scope of environmentally friendly production in reactive dyeing. In this study, the dyeing behavior of cotton using dyestuffs with different functional group numbers developed for this purpose and the properties of these dyes in washing wastewater solutions were investigated. The dyeing behaviors of fabrics dyed with reactive dyes with mono-, bi-and tri-functional group numbers were evaluated by colorimeter and color strengths. The absorbance and transmittance measurements of the wastewater of all baths of the reactive washing processes were performed. Despite using dye at the same concentration, higher color depth and similar fastness values were obtained with tri-functional dyes compared to the others. All of the tri-functional reactive washing baths had higher transmittance values than those of the others, except for the first one. It was thought that this could have been explained by the tri-functional dye was fixed to the fiber at a higher rate than the others. In addition, the gradually increasing transmittance values of tri-functional reactive washing wastewater were interpreted as contributing to sustainability by increasing the possibility of reuse of the final wastewater baths or reducing the number of washing baths.