8 Commercial Production of Ionic Liquids
203
Fig. 8.2 Pilot production using a counterflow extraction column (© IOLITEC, 2019)
be applied for the purification of similar ionic liquids. Though so far it has not
been applied on an industrial scale, it is an interesting and cost-effective purification
method.
8.2.3.2 Removing Water and Organic Solvents
Solvents with low boiling points, such as water and organic solvents, can be removed
by distillation at reduced pressure. Since ionic liquids are good solvents for numerous
types of solids including adsorption media, such as SiO 2 or zeolites, adsorption drying
techniques are not favored.
On the lab scale, rotary evaporators are commonly used for pre-drying and operate
at pressures of 0.1–0.5 bar. To meet higher specifications by reducing the amount of
solvents, a higher vacuum of (1–5) × 10
−3 bar has to be applied and can be achieved
by using oil pumps.
In principle, these steps can also be applied to the mid-scale (1–50 kg), but on
a scale of 50 kg and above, larger rotary evaporators, which so far can only be