Multiscale evaluation of the efficiently separation of phenols using a designed cationic functionalized ionic liquid based on Brønsted/Lewis coordination

Abstract Phenolic compounds (PCs) are value-added materials in producing medicines and disinfectants, which were enriched in the coal tar oils. However, the commonly industrial applied methods exposed several environmental concerns. Thus, the utilization separation of PCs using a green and sustainable technology present both commercial and biological value. In the present work, a type of simple and easy prepared carboxyl functionalized ionic liquid, 1-carboxyethyl-3-methylimidazolium nitrate ([CeMIM][NO3]), was designed based on the Bronsted/Lewis coordination theory and prepared to effective separation of PCs from the oil mixtures, taking m-cresol as the example. The total nonbonded interaction energy (Etotal), spatial distribution function (SDF) and averaged noncovalent interaction (aNCI) were calculated to reveal that the formed H-bonds were enhanced by the functional group of the adopted IL. Moreover, FT-IR was also performed to prove the H-bonds interaction and acid-base coordination with the IL. Afterwards, the performance was explored by measuring the variation of the extraction efficiency (E) under different separation conditions such as separation temperature (ST), the mass ratio of IL to model oil (mIL/moil), and extraction time (ET). Meanwhile, the separation performance of [CeMIM][NO3] on other phenols was also investigated and followed by the regeneration of [CeMIM][NO3]. The E values are 98.77 % for m-cresol, 97.65 % for o-cresol, 98.03 % for p-cresol and 98.14 % for phenol with mIL/moil = 1:5 and extraction time 30 min at 298.15 K.