Enhancing the Dyeing and Color Fastness Properties of Cotton Fabric Dyed with Curcumin: A Sustainable Double Mordanting Approach Using Waste-Derived Biomordants

Natural dyes are increasingly favored for their eco-friendly, sustainable, and non-toxic properties. However, their application in textiles is often hindered by limitations such as low color yield and poor fastness, which necessitate the use of mordants. This study investigates the effectiveness of a double mordanting technique to enhance the color strength and fastness of curcumin, a natural yellow dye derived from turmeric, on cotton fabrics. The double mordanting process involved the sequential application of waste-derived biomaterials (pomegranate rind, onion peel, and chitosan) and metallic mordants, followed by dyeing with curcumin. The dyed fabrics were comprehensively evaluated based on color parameters, color strength, levelness, and fastness. Results showed that double mordanting led to a significant improvement in both color strength—up to 69.68% higher—and wash fastness—up to 1.5 grades better—compared to traditional single mordanting. Additionally, the process reduced the residual metal content in the mordant bath by up to 27.00%, promoting a more sustainable dyeing method. Various combinations of biomordants and metal mordants were found to produce fabrics with diverse hues and shades. Notably, the combination of pomegranate rind and iron(II) sulfate yielded a rich, deep black shade on cotton. These findings underscore the potential of using waste-derived biomordants in a double mordanting process as an eco-conscious and effective strategy to enhance the performance of curcumin-dyed cotton while minimizing environmental impact.