Liquid membrane process for the separation of aqueous mixtures

Abstract

This invention relates to a process for the removal of dissolved species from aqueous solutions, which comprises contacting said aqueous solution with an emulsion, said emulsion comprising an exterior phase which is characterized as being immiscible with said aqueous solution and yet permeable to said dissolved species, and an interior phase which contains a reactant capable of converting said dissolved species to a non-permeable form. The dissolved species permeate the exterior phase, into the interior phase where they are converted into nonpermeable forms and thus retained in the interior phase of said emulsion. The aqueous solution, depleted in said dissolved species, is separated from said emulsion and the emulsion cycled for reuse. In one preferred embodiment said dissolved species are ions, and an ion exchange compound is incorporated in the exterior phase of the emulsion, to promote the permeation of said ions through the exterior phase.

What is claimed is: 
     
       1. A process for removal of a dissolved species from an aqueous solution which comprises, contacting said aqueous solution with an emulsion, said emulsion comprising an interior phase, surrounded by a surfactant containing exterior phase, said exterior phase being immiscible with said aqueous solution and said exterior phase being permeable to said dissolved species, and said interior phase comprising a reactant capable of converting said species to a nonpermeable species, whereby said species permeates the exterior phase and is converted to a nonpermeable species in the interior phase. 
     
     
       2. The process of claim I, wherein said exterior phase comprises from about 0.01 to 10 weight percent of an oil soluble surfactant. 
     
     
       3. The process of claim 2 wherein said interior phase is aqueous. 
     
     
       4. The process of claim 3 wherein said dissolved species is converted to a nonpermeable form by complexing with a reactant in the interior phase. 
     
     
       5. The process of claim 3 wherein said dissolved species is an ion. 
     
     
       6. The process of claim 5 wherein said exterior phase comprises an ion exchange compound. 
     
     
       7. The process of claim 6 wherein said ion is a cation. 
     
     
       8. The process of claim 7 wherein said exterior phase comprises a compound selected from the group consisting of sulfonic acids, organophosphoric acids and carboxylic acids. 
     
     
       9. The process of claim 6 wherein said ion is an anion. 
     
     
       10. The process of claim 9 wherein said exterior phase comprises an amine. 
     
     
       11. The process of claim 3 wherein said dissolved species is converted to a nonpermeable form in the interior phase by neutralization. 
     
     
       12. The process of claim 11 wherein said dissolved species is a weak acid and is neutralized in the interior phase by a strong base. 
     
     
       13. The process of claim 12 wherein said weak acid is selected from the group consisting of CO 2 , SO 2 , acetic acid, H 2  S, phenol, HCN and citric acid. 
     
     
       14. The process of claim 11 wherein said dissolved species is a weak base and is neutralized in the interior phase by a strong acid. 
     
     
       15. The process of claim 14 wherein said dissolved species is selected from the group consisting of NH 3  and nitrogen containing organic compounds. 
     
     
       16. The process of claim 3 wherein said dissolved species is converted to a nonpermeable form by precipitating in the interior phase. 
     
     
       17. The process of claim 16 wherein said dissolved species is selected from the group consisting of metal ions. 
     
     
       18. The process of claim 17 wherein said metal ion is selected from the group consisting of Ag, Cu, Cd and Hg. 
     
     
       19. The process of claim 3 wherein said surfactant is Span 80. 
     
     
       20. The process of claim 7 wherein said ion exchange compound is selected from the group consisting of sulfonated styrene copolymers, petroleum sulfonic acids, napthenic acids, sulfonated phenol formaldehyde copolymers, styrene-maleic acid copolymers, and styrene acrylic acid copolymers. 
     
     
       21. The process of claim 9 wherein said ion exchange compound is selected from compounds having the general formula: ##STR6## wherein R and R 1  are independently selected from the group consisting of hydrogen, C 1  to C 20  alkyl, C 6  to C 20  aryl and C 7  to C 20  alkaryl radicals and R 2  is selected from the group consisting of C 6  to C 30  alkyl, C 6  to C 20  aryl and C 7  to C 20  alkaryl radicals; and ##STR7## wherein R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9  and y are independently selected from the group consisting of hydrogen, C 1  to C 20  alkyl, C 6  to C 20  aryl, C 7  and C 20  alkaryl radicals and substituted derivatives thereof, and x is an integer of from 1 to 100. 
     
     
       22. The process of claim 21 wherein R 3  and R 4  together form an alkyl succinic radical having the general formula ##STR8## wherein m is an integer varying from 10 to 60, x varies from 3 to 10, and y is selected from the group consisting  of hydrogen and oxygen containing hydrocarbyl radicals having up to 10 carbons.