Ionic Liquids as Green Solvents for the Extraction of Endosulfan from Aqueous Solution: A Quantum Chemical Approach

Abstract

Abstract This work presents a judicious screening of 986 possible ionic liquid (IL) combinations for the removal of Endosulfan using COSMO-RS (Conductor-like Screening Model for Real Solvents) model. Initially, benchmarking studies have been carried out for α-Endosulfan, β-Endosulfan, Endosulfan sulfate, Endosulfan-alcohol, Endosulfan lactone, and Endosulfan ether by comparing COSMO-RS experimental and predicted octanol–water partition coefficients. Thereafter, COSMO-RS selectivity predictions were done on 986 ionic liquid combinations at infinite dilution. The order of selectivity for the five cation groups were found to be as follows: [TBP] > [TIBMP] > [TBMP] > [C2DMIM] > [BEPYR] > [DPPYR] > [C4DMIM] > [C8MPY] > [BTNH] > [BETNH]. Highest selectivity was obtained for phosphonium based IL namely: [TBP][TOS] (212.5). Anions such as [C8H17SO4], [Br], [Sal], [TOS], [MDEGSO4], and [DEC] contributed high selectivities because of the absence of sterical shielding effect around their charge centers. Further capacity and the performance index (PI) values were calculated and predicted along with selectivity. The increasing order of performance index values were found to follow: [TBP][Sal] (1.71+E5) > [DPPYR][Br] (1.07+E6) > [C2DMIM] (1.01+E6) > [C8MPY][Cl] (1.6+E5) > [BETNH][DEC] (1.2+E5).