Microwave-assisted vat dyeing of wool with binary natural anthraquinone dyes: A green leap toward sustainable textile processing

This study introduces a green and innovative approach to vat dyeing wool using a binary natural anthraquinone dye system derived from Juglans regia (walnut bark) and Kerria lacca (lac resin), enhanced through microwave (MW) irradiation. Wool fabrics were dyed with radiated and non-radiated extracts using bio- and metal-based mordants including Al 3+ , Fe 2+ /Fe 3+ salts, and vegetable-derived extracts (onion peel, pomegranate, and acacia). Microwave treatment for 4 min significantly improved dye uptake, increasing the K/S value from 14.29 (non-treated) to 16.80, with maximum yield reaching 18.91 % using Fe 2+ salt and onion peel extract as mordants. Colorimetric data revealed brighter, more saturated reddish-yellow to greenish tones depending on mordant type and application sequence. Fastness properties were notably enhanced, achieving ISO-rated values of 4–5 for wash, rub, and light exposure. This MW-assisted vat dyeing technique not only reduced energy and processing time but also promoted sustainable alternatives to synthetic dyes and hazardous mordants. The integration of natural dye sources, green mordanting agents, and microwave technology presents a viable eco-friendly strategy for sustainable textile coloration with enhanced performance and minimal environmental impact.