Electrochemical decolorization of textile dye baths and reuse in scouring and bleaching processes of cotton fabrics

Abstract

Water intensive textile pretreatment processes require substantial freshwater and chemical consumption, and reuse strategies have predominantly focused on dyeing rather than upstream operations such as scouring and bleaching. In this study, a circular pretreatment approach is proposed by directly reusing electrochemically decolorized reactive dye baths in cotton scouring and bleaching processes. Reactive Blue 222 dye baths (0.1 g/L) were treated under optimized electrochemical conditions (3 A, 30 min, 20 g/L NaCl, 5 g/L Na₂CO₃), achieving 95–97% color removal while maintaining alkaline conditions suitable for immediate reuse. The type of anode significantly influenced process performance, with iron electrodes providing the highest scouring and bleaching efficiencies. Scouring performance reached a vertical wicking height of 12.6 cm, corresponding to 105% of conventional treatment, while bleaching achieved Stensby whiteness values up to 76.7, representing 97% of conventional bleaching efficiency. In addition, increasing hydrogen peroxide or stabilizer dosage did not result in a significant improvement in bleaching performance, indicating that chemical inputs can be reduced without compromising efficiency. Overall, the proposed approach enables the elimination of freshwater usage, reduction of chemical consumption, effective color removal, and preservation of textile performance. The direct reuse of electrochemically treated dye baths in pretreatment processes represents a practical and scalable strategy for sustainable and circular textile manufacturing. These findings highlight the potential of electrochemical treatment as an integrated solution for water reuse and environmental impact reduction in industrial textile applications.