Author : Sawsan A.M. Mohammed and Mohammed Saadi Hameed

Room temperature ionic liquids show potential as an alternative to conventional organic membrane solvents mainly due to their properties of low vapour pressure, low volatility and they are often stable. In the present work, the technical feasibilities of room temperature ionic liquids as bulk liquid membranes for 4-nitrophenolphenol removal were investigated experimentally. In this research several hydrophobic ionic liquids were synthesized at laboratory and these ionic liquids (1-Butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, 1-Hexyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, 1-Octyl-3-methylimidazolium bis (trifluoromethylsulfonyl)imide,1‐Butyl‐1‐methylimidazoliumhexafluorophosphate, 1‐Hexyl‐1‐methylimidazoliumhexafluorophosphate, 1-Butyl-1-methylpyrrolidinium bis (trifluoromethylsulfonyl) imide, and 1-Octyl-3-methyl imidazolium tetra fluoroborate. The distribution coefficients for 4-nitrophenol in these ionic liquids were measured at different pH values and found to be much larger than those in conventional solvents. Through the values of the distribution coefficients and the experiments that were conducted on bulk liquid membrane applying various types of prepared ionic liquids, 1-Butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide was selected as the best ionic liquid which gave the greatest extraction and stripping efficiencies. The effects of several parameters, namely, feed phase pH(4.6-9.92), feed concentration(100-1000 ppm), NaOH concentration(0-0.5M), temperature (20-50oC), feed to membrane volume ratio (200-400ml/80ml ionic liquid) and stirring speeds(75-125 rpm) on the performance of the chosen ionic liquid membrane were also studied. The preliminary study shows that high phenol extraction and stripping efficiencies of 99% and 93% respectively were achieved by ionic liquid membrane with a minimum membrane loss which offers a better choice to organic membrane solvents.

Keywords: Liquid membrane, Ionic liquids, Cation, Anion, Extraction efficiency, stripping efficiency, Distribution coefficient.

Article published in International Journal of Current Engineering and Technology, Vol.6, No.2 (April-2016)