Water content in IL could be rather high. On other hand usualy high viscosity of IL and its afinity to water slow down removal of water from it. We use rotary evaporator at low presure. Thin film of IL is formed on the flask wall helps. The evaporation was done by gradually increasing the temperature of the bath from 70 oC to the final temperature of 140oC for 10 h, the final temperature was maintained for 2 h to minimize the temperature stress. Final pressure in the evaporator was 0.8 kPa. Water content in the dried product was 0.057 mass.%. (Blahusiak, M., J. Chem. Thermodyn., 72 (2014) 54)
