Method for separating oil from water

Abstract

A method for separating water-immiscible oils and oil-like substances from mixtures including said oils in an aqueous medium which comprises contacting the mixture with an oleophilic fibrous web comprising large numbers of interconnected, interstitial spaces for reception and retention of the oil to the exclusion of water.

What is claimed is: 
     
       1. A method for isolating water-immiscible oils from a mixture of said oils in an aqueous medium, said method comprising: a. contacting the mixture with a fibrous web which comprises a plurality of entangled oleophilic fibers, said fibers being hydrophobic in the presence of oil and having a diameter size in the range between about 0.1 micron to about 100 microns; said fibrous web having a bulk density, expressed as a percentage of fiber density, in the range between about 2 percent and about 35 percent;   b. allowing the oil to wet the fibrous web to the exclusion of the aqueous medium; and   c. removing the fibrous web from said mixture.   
     
     
       2. The method of claim 1 wherein the fibrous web comprises a material the surface of which, when contacted by oil in the presence of water, allows the oil to assume a contact angle with said surface which is substantially zero. 
     
     
       3. The method of claim 1 wherein at least 90 percent of the fibers comprising said web have diameters ranging between about 1 micron and about 5 microns, and wherein the web density, expressed as a percentage of fiber density, is between about 4 percent and about 8 percent. 
     
     
       4. The method of claim 1 wherein the fibers comprising the said web are of a material selected from the group consisting of polyesters, polyamides and polycarbonates. 
     
     
       5. The method of claim 1 wherein the fibers comprising said web are of a material selected from the group consisting of polypropylene, polyethylene and copolymers thereof, poly-4-methylpentylene, polytrifluorochloroethylene and polytetrafluoroethylene. 
     
     
       6. The method of claim 1 in which the oil-water mixture to be separated is in a relatively static state. 
     
     
       7. The method of claim 1 wherein the oil-water mixture to be separated is passed through said fibrous web. 
     
     
       8. The method of claim 1 wherein the isolated oil is removed from said web by squeezing the web. 
     
     
       9. The method of claim 1 wherein said isolated oil and said web are reclaimed by catalytic cracking. 
     
     
       10. The method of claim 1, wherein said isolated oil and said web are reclaimed by thermal cracking. 
     
     
       11. The method of claim 1 wherein said oleophilic fibers comprise a polyolefin polymer. 
     
     
       12. The method of claim 1 wherein said oleophilic fibers are polypropylene. .Iadd. 13. A method for isolating water-immiscible oils from a mixture of said oils in an aqueous medium, said method comprising: a. contacting the mixture with a fibrous web which comprises a plurality of entangled oleophilic fibers prepared by extruding liquid fiber-forming material through an opening into a gaseous stream where the extruded material is disrupted and drawn into fibers and then collected as a mass of said entangled fibers, said fibers being hydrophobic in the presence of oil and having a diameter size in the range between about 0.1 micron to about 100 microns; said fibrous web having a bulk density, expressed as a percentage of fiber density, in the range between about 2 percent and about 35 percent;   b. allowing the oil to wet the fibrous web to the exclusion of the aqueous medium; and   c. removing the fibrous web from said mixture. .Iaddend..Iadd. 14. A method of claim 13 wherein 90 percent of the fibers comprising said web have diameters ranging between about 1 micron and about 5 microns. .Iaddend..Iadd. 15. A method of claim 13 or 14 wherein the fibrous web has a bulk density, expressed as a percentage of fiber density, in the range between about 4 and 8 percent. .Iaddend..Iadd. 16. A method of claim 13 or 14 wherein the said oleophilic fibers are polypropylene fibers. .Iaddend. .Iadd. 17. A method of claim 1 in which the fibrous web is laid on the surface of the aqueous medium so as to contact said mixture with the web, and the fibrous web comprises a plurality of entangled oleophilic microfibers which are hydrophobic in the presence of oil and which are prepared by extruding liquid fiber-forming material through an opening into a gaseous stream where the extruded material is disrupted and drawn into fibers and then collected as a mass of said entangled fibers. .Iaddend. .Iadd. 18. A method of claim 17 wherein the microfibers comprise polypropylene. .Iaddend..Iadd. 19. A method of claim 17 wherein 90 percent of the fibers comprising said web have diameters ranging between about 1 micron and about 5 microns. .Iaddend..Iadd. 20. A method of claim 17 or 19 wherein the fibrous web has a bulk density, expressed as a percentage of fiber density, in the range between about 4 and 8 percent. .Iaddend..Iadd. 21. A method of claim 1 in which the fibrous web comprises a plurality of entangled oleophilic microfibers which are hydrophobic in the presence of oil, and which are prepared by extruding liquid fiber-forming material through an opening into a gaseous stream where the extruded material is disrupted and drawn into fibers and then collected as a web of said entangled fibers; said fibrous web including large numbers of interconnected interstitial voids into which oil is received and retained substantially to the exclusion of water. .Iaddend..Iadd. 22. A method of claim 21 wherein the microfibers comprise polypropylene. .Iaddend..Iadd. 23. A method of claim 21 wherein 90 percent of the fibers comprising said web have diameters ranging between about 1 micron and about 5 microns. .Iaddend..Iadd. 24. A method of claim 21 or 23 wherein the fibrous web has a bulk density, expressed as a percentage of fiber density, in the range between about 4 and 8 percent. .Iaddend. .Iadd. 25. A method of claim 1 in which the fibrous web is laid on the surface of the aqueous medium so as to contact said mixture with the web, and the fibrous web comprises a plurality of entangled oleophilic polypropylene microfibers which are hydrophobic in the presence of oil and which are prepared by extruding liquid-forming material through an opening into a gaseous stream where the extruded material is disrupted and drawn into fibers and then collected as a web of said entangled fibers; said fibrous web including large numbers of interconnected interstitial voids into which oil is received and retained substantially to the exclusion of water. .Iaddend..Iadd. 26. A method of claim 25 wherein 90 percent of the fibers comprising said web have diameters ranging between about 1 micron and about 5 microns. .Iaddend..Iadd. 27. A method of claim 25 or 26 wherein the fibrous web has a bulk density, expressed as a percentage of fiber density, in the range between about 4 and 8 percent. .Iaddend.