Quantum Chemical Based Screening of Ionic Liquids for the Extraction of Phenol from Aqueous Solution

Room-temperature ionic liquids (ILs), because Of their various advantages, are superior extractants than the traditional volatile organic solvents (VOCS) used for liquid-liquid extraction. This work reports the judicious screening of various ILs for the extraction of phenol from aqueous solutions. A quantum chemical based conductor-like screening model for real solvents (COSMO-RS) is used for the prediction of selectivity of phenol in aqueous medium at infinite dilution. A combination of 16 cations and 26 anions, which resulted in 416 possible ILs, is used to determine the best extractant for the removal of phenol from aqueous solutions. During the screening process, [TBTDP] and [OMIM] gave the highest selectivity among the phosphonium and imidazolium based cations, respectively. Similarly, the favorable anions are those where no sterical shielding effect around their charge centers exists, such as [CH3SO3], [OAc], [Cl], and [Br]. The best IL screened is [OMIM][Dec], which gave the highest selectivity of 111.