Dyeing and Multifunctional Finishing of Cotton Fabrics Using Ethiopian Rumex steudelii Root Extract: Response Surface Optimization, LC-MS/MS Phytochemical Profiling, and Antibacterial and UV-Protective Performance

Abstract

Abstract

Abstract Textile finishing increasingly demands sustainable, multifunctional alternatives to synthetic dyes and biocides. This study developed a single-bath, metal-free strategy to simultaneously color and biofunctionalize 100% cotton fabric using Rumex steudelii root extract. Ultrasonic-assisted extraction was optimized by response surface methodology (central composite design, CD); experimental yield ranged from 29.95% to 40.13% across the design space. The desirability-based optimum, selected to minimize temperature, time, and solvent use, was ≈55 °C, 32 min, and a 10 mL/g liquid-to-solid ratio, a predicting yield of 34.51%, which was confirmed experimentally (33.90 ± 0.18%, prediction error 1.77%). LC-MS/MS annotated 27 constituents (24 confirmed with authentic standards), dominated by flavonoids (35.38%), phenolic acids (22.25%), and anthraquinones (19.28%), providing a chemical basis for coupling coloration with bioactivity. Dyeing with the extract alone, or with citric acid or tannic acid as green cross-linkers, produced three distinct, reproducible shades (golden yellow, burnt orange, and earth brown) with color strength (K/S) of 4.42 to 10.34, and washing, rubbing, and light fastness improved to grades of 4/5–5. Cross-linked fabrics achieved excellent UV protection (UPF up to 56) and strong antibacterial activity, reducing Staphylococcus aureus and Escherichia coli counts by up to 99.8 ± 0.23% and 97.3 ± 0.81%, respectively. By integrating RSM-optimized extraction, LC-MS/MS-resolved phytochemical mapping, and single-bath, metal-free cross-linking in one process, this work establishes Rumex steudelii as a promising platform for multifunctional natural textile finishing, with potential for scale-up pending pilot-scale validation.