Advanced reverse micellar extraction: a high-efficiency approach for sustainable removal of Xylenol Orange from wastewater

Abstract This study presents an innovative and highly effective reverse micellar liquid-liquid extraction approach for the removal of the anionic dye Xylenol Orange (XO) from aqueous solutions. The extraction process was facilitated by the cationic surfactant cetylpyridinium chloride (CPC), which formed reverse micelles in different organic solvents – toluene, m -xylene, hexane and cyclohexane – allowing selective encapsulation and separation of the dye by gravitational settling. Among the solvents tested, toluene exhibited the highest dye removal efficiency, demonstrating its superior ability to stabilise reverse micelles. Kinetic analysis revealed that the extraction process followed pseudo-first order kinetics with a rate constant of 0.016 min −1 and a half-life of 43.3 min. In addition, increasing the pH of the solution from 7 to 12 significantly improved the extraction efficiency, which was attributed to the increased anionic character of the dye, which improved its interaction with the cationic surfactant. This study highlights the potential of reverse micellar extraction as a highly efficient, cost-effective and environmentally friendly alternative to conventional dye removal techniques. The method not only ensures high extraction efficiency with minimal sludge production, but also offers a promising strategy for industrial wastewater treatment.