Green dyeing of wool using microwave-assisted anjbar root extract and bio-mordants

The primary goal of using natural dyes is to minimize environmental contamination by reducing toxic effluent discharge, water pollution, and energy consumption compared with conventional synthetic dyes. Due to the increasing demand for sustainable and biodegradable products, research on the applications of natural dyes in the textile industry is expanding globally. This research explores an eco-friendly dyeing process for wool yarn using natural pigments extracted from the roots of the anjbar plant (Bistorta officinalis). This study evaluated the effectiveness of extracting tannin-based natural colorants from anjbar roots using microwave treatment for up to 6 min, followed by their application in wool dyeing. The results indicate that irradiating wool yarn at 65°C for 55 min with a pH 6 extract containing 1% NaCl as an exhausting agent yielded excellent dyeing results in an aqueous medium. Salts of aluminium, iron, chromium (Cr), copper (Cu), cobalt (Cu), and nickel (Ni) (0.5%–2.5%) were utilized as chemical mordants due to their effectiveness in enhancing color shades; however, recognizing potential environmental concerns associated with certain metal salts (especially Cr, Cu, Co, and Ni), bio-mordants were also explored as environmentally friendly alternatives. In addition, extracts from onion peels, pomegranate, chamomile, and yellow sumac (0.5%–2.5%) served as bio-mordants, enhancing color shades and improving fastness properties. The study highlights the efficacy of microwave extraction techniques in maximizing color yield and mordant performance, showcasing the versatility of natural pigments. Furthermore, the successful integration of various bio-mordants not only enriches the palette of available colors but also reinforces the commitment to sustainable and biodegradable dyeing processes.