Process for workup of glycol-containing aircraft deicers

1. A method for reprocessing a used aircraft de-icing agent comprising glycol and suspended impurities, wherein the method comprises the steps of:

(1) separating off the suspended impurities from the used aircraft de-icing agent to form a partially reprocessed used aircraft de-icing agent,

(2) treating the partially reprocessed used aircraft de-icing agent obtained from step (1) such that any thickeners present therein are no longer capable of gel formation,

(3) before or after step (2), adjusting to a pH>7 by adding potassium hydroxide,

(4) followed by fractionally distilling off the glycols.

2. The method as claimed in claim 1 , in which the separating off step (1) involves a coarse filtration, and a subsequent ultrafiltration through a membrane.

3. The method as claimed in claim 1 , wherein the partially reprocessed used aircraft de-icing agent from step (1) is alkalized and then subjected to a first distillation stage in which water is separated off.

4. The method as claimed in claim 3 , wherein the alkalization takes place with at least 0.1% by weight of potassium hydroxide, based on the partially reprocessed used aircraft de-icing agent from step (1).

5. The method as claimed in claim 1 , wherein prior to being used to de-ice an airplane, the used aircraft de-icing agent comprises,

(a) 1 to 60% by weight, of at least one glycol having 2 or 3 carbon atoms or of a diglycol having 4 to 6 carbon atoms,

(b) up to 0.8% by weight of water-soluble polymers selected from the group consisting of polyacrylates and polymethacrylates,

(c) 0.01 to 1% by weight of surfactants, and

(d) 0.001 to 0.1% by weight of corrosion inhibitors, with the remainder being water.