Recovery of ionic liquids from wastewater: Aggregation control for intensified membrane filtration

Based on the hypothesis that ionic liquids should show a similar behaviour as surfactants in membrane filtration, this research work analyses the potential of aggregation control to improve the performance of downstream membrane separations, applied to the system 3-octyl-1-methylimidazolium chloride (OMIM-Cl), water and iron(III) chloride (FeCl3). It was obtained that the addition of FeCl3 has an important effect on CAC value and its increase has consequences on the design of the corresponding membrane filtration system.

The following conclusions can be made: 1. Addition of kosmotropic cation (Fe+3) increases CAC and allows aggregation control. It can be assumed that the addition of chaotropic cations lowers CAC. 2. Treating low concentrated feed in a second stage aggregation enhances permeate flux. The consequence on ionic liquid retention is to be investigated.