Microwave-assisted sustainable coloration of wool fabric using Rheum emodi-based natural dye

The use of natural colorants in modern dye factories is a potential green chemistry idea that should be widely promoted to minimize the dependency of wool dyeing on some hazardous and non-biodegradable synthetic colors. In this study, an effort was undertaken to see if Rheum emodi (rhubarb) extract might be used as a natural dye for wool dyeing for the replacement of synthetic dyes. The dyeing of wool fabric was carried out using microwave (MW) ray treatment. By combining several mordants, a stunning color palette of shades of varying hues and tones was created. Comparative evaluation of the effects of various chemical mordants (aluminum salt, iron salt, tannic acid and cream of tartar) and bio-mordants (pomegranate extract and pine nut hull extract) on the characteristics of dyed wool samples was carried out to choose the best mordant for each application. It was found that MW-treated wool fabric using a bio-mordant showed a higher colorfastness value of 4/5 to 5 and a color strength value of approximately 10–20 than using metallic mordant. Scanning electron microscopy photographs and Fourier transform infrared spectroscopy analyses revealed the difference between irradiated and unirradiated wool fabrics. The employment of MW rays and bio-mordants in the natural coloring of wool fabric is encouraged due to their biocompatibility and non-toxicity when combined with MW treatment of wool fabric, as well as their high colorfastness and color strength performance. As a result, naturally extracted dyes from rhubarb can be a replacement for synthetic dyes for the coloration of wool fabric in the textile industry due to their environmental friendliness.