A green dye wastewater treatment process: Complex extraction of Telon yellow 4R from dye wastewater and its application in nylon fabric dyeing

Abstract Complex extraction, which has the characteristics of high efficiency and selectivity of chemicals, has unique advantages in dye wastewater treatment. In the paper, a green closed‐loop dye wastewater treatment route for dyeing industry is re‐evaluated by studying the complex extraction and stripping of Telon yellow 4B, and dyeing test of regenerated dye. FT‐IR characteristic peaks of the initial organic phase and the regenerated organic phase are consistent, and the dye can be migrated from the loaded organic phase to the aqueous phase after stripping. The concentration of dye in the aqueous phase and extraction conditions have a significant effect on extraction rate, especially the aqueous‐organic phase ratio and the pH value of the aqueous phase. Meanwhile, the stripping conditions have a marked impact on stripping rate, among which NaOH dosage is an important factor. The regenerated dye solution and the freshly prepared dye solution at same concentration have the same color shade and K/S value, and the color fastness of dyed fabrics is all above Grade 4. High extraction rate, high stripping rate, excellent reusability of regenerated organic phase, and the dyeing performance of the regenerated dye prove that complex extraction is a green dye wastewater treatment process with the practical feasibility.