Parameter Wastewater Model solution Feed concentration, CF (g/L) 1.826 1.838 Mean permeate flux, JPm (L/m2h) 22.2 33.1 Retention, R (%) 63.1 95.2 Ionic liquid Recovery, Rec (%) 50.5 75.6

Table 1: Effect of wastewater components on nanofiltration performance and ionic liquid recovery for IM16 (CF3SO2)2N. Experiments were carried out using a deadend stirred cell (25°C, 35 bar, 80% feed recovered as permeate) and the Desal DK membrane was used.