Process for cleaning an ionic liquid and method for dehumidifying air

Ionic liquids of the structure Q + A-, where Q + is a 1,3-dialkylimidazolium ion in which the alkyl groups are independently linear C1-C4 alkyl groups and A- is the anion of an acid HA with a pKa of less than 3 Clean by desorption of volatile compounds at a temperature of 100 to 200 ° C and a pressure of 100 mbar for a minimum of 0.1 h and use for dehumidification of air.