A Review on the Dye Extraction Methods from Weld

Reseda luteola is a plant species in the genus Reseda. The common name is weld. The plant is rich in luteolin, a flavonoid that produces a bright yellow dye. This dye is more important and noticeable than other natural yellow dyes due to its high transparency and color strength, and better general fastness. Cellulose and waste tissue in natural dyes reduce the efficiency and quality of natural dyeing, occupy a large volume of dyeing equipment with dye plant pulp and complex dye matching. To make maximum use of the dye in the plant, applying the extraction methods is inevitable. Much research has been done in the field of dye extraction from this plant. Extraction of natural dyes from weld with the help of traditional methods such as boiling, soaking and steaming and modern techniques such as Soxhlet, microwave, ultrasound, plasma, membrane, critical liquid and the effect of various solvents such as water, methanol, ethanol, water-ethanol, and water Methanol as well as auxiliaries during dyeing and extraction have been considered by researchers. The results show the effectiveness of some extraction methods compared to the conventional method, different solvents, and the effects of extraction bath pH. The results of dye extraction from weld using filtration methods and wool dyeing led to the superiority of deposition of dyes by alum mordant and then ultrafiltration. Compared to Soxhlet extraction methods with the ultrasonic technique, extraction efficiency was superior and less time and energy was spent in the ultrasound method showed excellent extraction efficiency. In general, research has been demonstrated that dye powder extracted from weld can be used instead of the plant. In addition, use in the pharmaceutical and health industries increases the efficiency and quality of dyeing and can be an excellent alternative to synthetic dyes. In this study, the researches related to different dye extraction methods from the weld, the effect of solvents and auxiliaries on the extraction efficiency, and dyeing quality are reviewed and introduced.