Partitioning behavior of dyes in ionic liquids induced aqueous biphasic systems of PPG 725 & ammonium salts

Polypropylene glycol (PPG) is one of the most utilized polymers in aqueous biphasic systems. The low polarity of the polymer-rich phase restricts the application of the ABSs. The applicability of polymer rich ABSs can be induced by adding little amount of ionic liquids as adjuvants. Therefore, an analysis involving the introduction of a small amount of imidazolium-based ILs to PPG 725 + ammonium salts ABSs was performed. The phase diagrams as well as the partitioning behavior of dyes: Orange II (OII), Eriochrome Black T (EBT) and Brilliant Green (BG) were investigated. The addition of 5% 1-butyl-3-methylimidazolium acetate, [BMIM][AC] modulates the partition behaviors of all the investigated dyes. The employed ILs and dyes partitioned preferentially into the polymer-rich phase. The partition coefficients (K-dye) for all the dyes follow the sequence: BG > EBT > OII in all investigated ABSs. The results obtained are in accordance with the logarithm of octanol-water partition coefficients (log Kow) of the respective dyes. The recovery of BG dye from polymer phase has been studied successfully by adsorption onto chitosan.