Recovery of Ionic Liquids from aqueous solution by Nanofiltration

Abstract

The T-SAR methodology was combined with membrane characterization methods. An application of the combined approach was demonstrated with two commercial nanofiltration membranes and it was possible to successfully predict their performance for the recovery of ionic liquids from aqueous solution. Using model solutions of Pyr16 (CF3SO2)2N, it could be evidenced the formation of a new phase of ionic liquid during the concentration process. In this case, 66% of the ionic liquid was separated and the effective recovery rate was duplicated up to 30% by using a coalescence filter. Hydrophobic ionic liquids from wastewaters produced in biotransformations of 2-octanone to 2-octanol, could be recovered as a separate phase, but hydrophilic ionic liquids which are used for the dissolution of cellulose and its subsequent regeneration could be only recovered as an aqueous solution. Recommendations for the systematic recovery of ionic liquids from industrial wastewaters were also introduced.