Extraction of Phenol and Chlorophenols Using Ionic Liquid [Bmim]+[BF4]− Dissolved in Tributyl Phosphate.

In the present work, experiments have been carried out with a focus to reduce the volume requirement of solvent by mixing with imidazolium based ionic liquids (ILs) for the solvent extraction of phenol, p-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol from aqueous solutions. The effect of aqueous phase pH (2-12), agitation speed (100-450 rpm), solute concentration in feed (2-50 mg/L), temperature (303-333 K), treat ratio (1-11), and 1-butyl-3-methyl imidazolium tetrafluoroborate [Bmim]⁺[BF₄]⁻ volume in tributyl phosphate (TBP; 0-0.7% v/v) on extraction of phenols has been studied and optimized. Parameters like strip phase pH (3-13) and stripping agent concentration (0.001-0.009 N) have also been studied for stripping of phenols from solvent phase. It has been found that 0.5% v/v of ionic liquid [Bmim]⁺[BF₄]⁻ in solvent TBP extracts more than 97.5% of phenol and chlorophenols from aqueous solutions with a treat ratio (aqueous to solvent phase ratio) of 5. Transport mechanism for extraction and stripping of phenol and chlorophenols using ionic liquid [Bmim]⁺[BF₄]⁻ has been discussed. The results show that by appropriate selection of extraction and stripping conditions, it is possible to remove nearly all phenols with a treat ratio of 5. [ABSTRACT FROM AUTHOR]