Method for recovering fluorinated emulsifiers from aqueous phases

The invention relates to the work-up of waste water, in particular lightly contaminated waste water, containing fluorinated emulsifiers, as employed in the polymerization of fluorinated monomers since they do not have telogenic properties. In particular, the salts, preferably the alkali metal or ammonium salts, of perfluorinated or partially fluorinated alkanecarboxylic acids or sulfonic acids are used. These compounds are prepared by electrofluorination or by telomerization of fluorinated monomers, which is associated with considerable effort. There has therefore been no lack of attempts to recover these valuable materials from waste water. Fluorinated emulsifiers can be recovered from an aqueous phase containing small amounts of fluoropolymer particles by treating the aqueous phase with a small amount of a nonionic surface-active agent, bringing the aqueous phase adjusted in this way into contact with an anionic exchanger resin, and liberating the adsorbed emulsifier from the exchanger resin. The finely divided fluoropolymer can be precipitated quantitatively in the untreated aqueous phase or the eluate using flocculating agents.