REMOVAL OF DYE FROM AQUEOUS WASTEWATER USING THE TECHNIQUE OF LIQUID-LIQUID EXTRACTION WITH IONIC LIQUID

Ionic liquid-based liquid-liquid extraction has been applied in the technology in extraction of methylene blue dye. Aiming at separating dye from the aqueous wastewater with highly efficient technique, low cost and low time consuming, the study suggested a novel approach by synthesizing imidazolium ionic liquid as the extraction solvent.
1-(2-Cyano-ethyl)-3-methyl-3H-imidazol-1-ium bis (trifluromethylsulfonyl) imide, [3-CIm][NTF2] and 1-(2-Cyano-butyl)-3-methyl-3H-imidazol-1-ium bis (trifluromethylsulfonyl) imide, [5-CIm][NTF2] were subjected in investigating the extraction efficiency under the effect of the length of the alkyl chain on the anion side. The external factors in determining the extraction efficiency were extensively studied based on the variation of the mass ratio of ionic liquid with aqueous dye solution and the pH of the aqueous medium. The results obtained allow the analysis of a suitable ionic liquid with a certain alkyl chain length can lead to complete extraction in shortest time and highest partition coefficient of the ionic liquid and methylene blue.
The physiochemical properties of the synthesized ionic liquid had been tested to ensure the properties of the ionic liquid. The cation structure, [NTF2]- was predominantly responsible for the bond forming with the amine structure of the methylene blue due to its hydrophobicity nature. In general, the length of the alkyl chain and the structure of the cation and ionic had highly impacted the extraction efficiency. The position of the cation and anion structure of the synthesized ionic liquid had been confirmed by the H-NMR spectroscopy upon the imidazolium anion had exchanged with anion of lithium bis (trifluromethylsulfonyl) imide. Since the hydrophobicity nature of ionic liquid is important, further studies on the impurities such as water content and viscosity had conducted. Thermal Degradation of the ionic liquid by using Thermogravimetric Analysis (TGA), was subjected to the study of thermal stability of the ionic liquid.