Extraction and preparation of dye powders from Reseda luteola L. using membrane processes and its dyeing properties

In this study, membrane processes were used to concentrate and prepare natural dye powder from Reseda luteola L. (Weld plant). First, the parameters of dye extraction such as time, temperature and pH were optimized. In the second place, concentration was performed in three ways: UF/RO, UF/NF and RO. Ultrafiltration (UF) membrane was prepared using acrylic fibers via phase separation, nanofiltration (NF) membrane was synthesized on ultrafiltration membrane via interfacial polymerization and also, reverse osmosis (RO) membrane was purchased. 0.3, 0.26 and 0.35 g of dye powder per gram of crushed Weld plant was obtained, respectively. Finally, wool fibers were dyed using these dye powders. After that, the properties of fibers like color characteristics and strength were characterized. Also, fastness properties of samples including light, rubbing, washing and staining were measured. Results showed a decrease in lightness or yellow tint. Color strength and light fastness of samples was very good. Rubbing and staining fastness of samples were also excellent. Washing fastness indicated moderate to good stability. It is suggested that since membrane processes are physical processes, no chemical changes did not take place on the dye powder and thus, the fastness did not change. •Dye extraction from Reseda luteola L. (Weld plant) was optimized.•Dye powders of Weld plant were prepared by membrane processes.•RO process had the highest efficiency between processes (0.35 g/1 g of Weld plant).•Wool fibers were dyed with these new natural dye powders.•Dye powder from UF/RO process had the highest brightness and color strength.•There was no change in light fastness.