Dye and Solvent Recovery in Solvent Extraction Using Reverse Micelles for the Removal of Ionic Dyes

Abstract

Among the several methods, dye removal from water by solvent extraction using reverse micelles is promising in terms of the simplicity and efficiency of the process. The recovery of solvent and reuse of dye after its removal is related to the economic viability of the process. In the present study, backward extraction or recovery of dye into an aqueous phase from the solvent phase by using a counterionic surfactant after forward extraction is experimentally studied using a simple mixer and settler arrangement. The backward extraction of dye also resulted in the recovery of solvent. The effects of different parameters, such as the surfactant concentration, pH, and KCl concentration on the recovery of methyl orange and methylene blue dyes, are investigated. The percentage of both cationic and anionic dyes recovered increases with an increase in the counterionic surfactant concentration or with a decrease in the KCl concentration. The percentage of recovery of anionic methyl orange increases with a decrease in pH, whereas that for cationic methylene blue increases with an increase in pH. Selective removal of dye from a cationic and anionic dye mixture was experimentally studied by treating the dye mixture with reverse micelles of anionic and cationic surfactants in a stepwise manner. The results obtained are explained based on electrostatic interaction between the surfactant and dye.