Research on the application of eco-friendly mordant in wool fabrics dyed with natural curcumin

Purpose The purpose of this paper is to screen out environmental mordants with good performance and less wastewater pollution by studying the mordanting effects and environmental problems of six different types of mordants in the natural curcumin dyeing of wool fabric. Design/methodology/approach In this study, the one-bath two-step post-mordant dyeing method was used for the dyeing of wool fabrics with natural curcumin pigment. The dyeing properties of the dyed wool fabric and the comprehensive indicators of the dyeing wastewater were tested. The mordanting effects and environmental problems of six kinds of mordants were compared. Based on this, the most effective and eco-friendly mordant was selected. Findings The test results of wool fabrics mordanted with citric acid exhibited high K/S values (second only to potassium dichromate) and color difference values (>25), surpassed only by darker mordants (potassium dichromate and pomegranate peel). Citric acid generated dyeing wastewater with the lowest chemical oxygen demand, ammonia nitrogen and hexavalent chromium among six mordants, significantly reducing environmental impact. Color fastness tests showed excellent results (= 4 for all except sunlight fastness). Given its colorless, easily degradable nature and superior eco-friendly performance alongside effective mordanting, citric acid is identified as the optimal environmentally sustainable mordant for curcumin-dyed wool fabrics. Originality/value At present, there are few reports on the systematic research of screening eco-friendly mordants for the dyeing of natural dyes, and the application of eco-friendly mordants in the dyeing of natural dyes belongs to the clean production process, which is beneficial to environmental protection and sustainable development.