Process for the recovery of fluorosurfactants by active charcoal
View Patent ↗The present invention relates to a process for the recovery of a fluorosurfactant present in an aqueous solution, in a gaseous effluent or in both involving a) obtaining an aqueous solution or gaseous effluent comprising 1 to 1,000 ppm of surfactant, b) removing any suspended solids, c) optionally concentrating the solution, d) passing the aqueous solution over a stationary bed of granular active charcoal such that all the surfactant is adsorbed without any solvents being adsorbed, e) halting the passage of the solution and gaseous effluent over the beds of activated charcoal which are eluted with a solution comprising a solvent and an inorganic acid, and then f) treating the solution recovered in stage e) to regenerate the fluorosurfactant.
1. Process for the recovery of a fluorosurfactant present in an aqueous solution comprising the steps of:
a) obtaining an aqueous solution comprising:
1 to 1,000 ppm of surfactant,
up to 1,000 ppm of solvents, expressed in COD (chemical oxygen demand), and
0 to 1,000 ppm of suspended solids;
b) filtering and/or clarifying the aqueous solution to remove any suspended solids which may be present;
c) optionally concentrating the resulting filtered and/or clarified solution from step (b);
d) passing the aqueous solution from step (b) or (c) over a stationary bed of granular active charcoal such that all the surfactant is adsorbed on the charcoal without the solvents being adsorbed;
e) halting the passage of the solution over the bed of granular activated charcoal and eluting the same with a solution comprising a solvent and an inorganic acid; and
f) treating the solution recovered in stage e) to regenerate the fluorosurfactant.
2. Process according to claim 1 , in which the surfactant is of general formula: ZC n F 2n COOM, in which Z is a fluorine or chlorine atom, n is an integer with a value from 6 to 13 and M is a hydrogen or alkali metal atom or an ammonium group or an ammonium group comprising at least one lower alkyl substituent.
3. Process according to claim 1 , in which the concentration of the surfactant in the aqueous solution is between 10 and 200 ppm.
4. Process according to claim 1 , in which the concentration of the solvents in the aqueous solution is up to 500 ppm.
5. Process according to claim 1 , in which the content of the suspended solids in the aqueous solution is up to 500 ppm.
6. Process according to claim 1 , in which the elution solution comprises, by weight, 75 to 95% of methanol, 5 to 15% of sulphuric acid and 0 to 20% of water.