Processes for the separation of potassium salts of perfluoroalkanoic acids from aqueous solutions thereof

A process for the separation of a potassium salt of a perfluoroalkanoic acid having at least 1 and at most 12 carbon atoms per molecule or a mixture of potassium salts of a homologous mixture of the said perfluoroalkanoic acids from an aqueous solution that also contains a substantial proportion of one or more water-soluble salts of inorganic acids, which process comprises extracting at room temperature the said aqueous solution with an organic solvent that is at least partially miscible with water and in which potassium salts of the said perfluoroalkanoic acids are soluble, the said organic solvent being selected from the group consisting of alkanols having at least 3 and at most 5 carbon atoms per molecule, ketones having at least 3 and at most 5 carbon atoms per molecule, N,N-dimethylformamide, and dimethyl sulfoxide, and subsequently recovering the potassium salt of the perfluoroalkanoic acid or mixture of potassium salts of the homologous mixture of perfluoroalkanoic acids from the extract.

A process for the separation of a potassium salt of a perfluoroalkanoic acid having at least 1 and at most 12 carbon atoms per molecule or a mixture of potassium salts of a homologous mixture of the said perfluoroalkanoic acids from an aqueous solution that also contains a substantial proportion of one or more water-soluble salts of inorganic acids, which process comprises removing the potassium salts of said perfluoroalkanoic acids by extracting at room temperature the said aqueous solution with a polar organic solvent under non-acidic conditions, said organic solvent being at least partially miscible with water and in which potassium salts of the said perfluoroalkanoic acids are soluble, the said organic solvent being selected from the group consisting of alkanols having at least 3 and at most 5 carbon atoms per molecule, ketones having at least 3 and at most 7 carbon atoms per molecule, N,N-dimethylformamide, and dimethyl sulfoxide, and subsequently recovering the potassium salt of the perfluoroalkanoic acid or mixture of potassium salts of the homologous mixture of perfluoroalkanoic acids from the extract.

A process for the separation of a potassium salt of a perfluoroalkanoic acid having at least 1 and at most 12 carbon atoms per molecule or a mixture of potassium salts of a homologous mixture of the said perfluoroalkanoic acids from an aqueous solution that also contains a substantial portion of one or more water-soluble salts of inorganic acids, which process comprises extracting at room temperature the said aqueous solution with a polar organic solvent under non-acidic conditions, said organic solvent being at least partially miscible with water and in which potassium salts of the said perfluoroalkanoic acids are soluble, the said organic solvent being selected from the group consisting of alkanols having at least 3 and at most 5 carbon atoms per molecule, ketones having at least 3 and at most 5 carbon atoms per molecule, N,N-dimethylformamide, and dimethyl sulfoxide, and subsequently recovering the potassium salt of the perfluoroalkanoic acid or mixture of potassium salts of the homologous mixture of perfluoroalkanoic acids from the extract.