Circular Dyeing Process of Cotton Fabrics Based on Multiple Reuses of Residual Dyebaths: Study of Dyeing Performances with Single Dye, Binary and Ternary Mixtures

This work reports on the feasibility of employing the residual dyebath reuse technique for dyeing cotton fibers with reactive dyes. For this purpose, three reactive dyestuffs were used separately and in mixtures to dye cotton fabrics. After each dyeing cycle, residual dyebaths were analyzed, reconstituted, and reused multiple times for various shades and mixtures. Several parameters were assessed to evaluate the effectiveness of the dyebath reuse method, including dyebath exhaustion, CIELab coordinates, and color fastness. In this study, it is demonstrated that the dyebath reuse method can substantially decrease the use of water, dyes, and auxiliary quantities while maintaining the performance of the dyeing process. In order to assess the environmental impact of the different residual dyebaths, COD and BOD₅ values were evaluated and discussed. Sustainable practices in the textile industry can be achieved through the implementation of these findings, which also provide a viable solution to reduce its environmental footprint.