Microwave-Assisted Extraction of Natural Dye from Rubia tinctorum L. Plant for Dyeing Wool Fabrics with Multiple Effects

Natural dyes are a more environmentally friendly option. However, despite their durability, the dye content in plant sources remains relatively low. This study aims to improve the extraction yield of natural dye from Rubia tinctorum L., develop a more appropriate and standardized technique for reaching deeper and higher color strength, and assess the dyed fabric’s UV protection and antimicrobial properties. Microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE) techniques were implemented and compared to the traditional reflux heating (RH) method. The extraction process parameters were optimized using a full factorial design to obtain high dye yields. The optimal extract was subjected to extensive characterization using UHPLC-PDA, FTIR, XRD, UV–VIS, SEM–EDX, DSC, proton NMR, TGA, and DTG techniques, confirming the success of the extraction process. The best performance was achieved with a dye extraction yield of 11.53% using MAE for 3 min at 900 W with 80% ethanol. This extraction yield has not been reported previously but under such mild conditions. The color strength of extracted dyes was assessed by dyeing wool fabrics using three extraction techniques. The results were evaluated using Datacolor measurement tools, FTIR spectroscopy, and light microscopy. Similarly, the dyed samples with the MAE technique achieved a higher color strength, reaching a K/S value of 28.68, and an excellent protection value with UPF of 74. The overall results highlight the potential of modern methods as valuable tools for producing highly concentrated natural dyes with excellent UV protection properties for textile applications.