Membranes and methods useful for caustic applications

• US 7,575,687 B2
• Filed: 07/28/2006
• Issued: 08/18/2009
• Est. Priority Date: 08/16/2005
• Status: Active Grant

• Current Assignee: GE Osmonics, Inc. (General Electric Company)
• Original Assignee: GE Osmonics, Inc. (General Electric Company)
• Inventors: Rolchigo, Philip M., Kurth, Christopher J., Kloos, Steven D., Iverson, Isaac K., Hodgins, Leonard T.
• Primary Examiner(s): Fortuna; Ana M
• Application Number:
  US11/495,810
• Publication Number:
  US 20070039885A1
• Time in Patent Office: 1,117 Days
• Field of Search: 210651-653, 210/500.27, 210/500, 210/39, 210/500.38, 210/639, 423121-122, 423/130
• US Class Current: 210/651
• CPC Class Codes: B01D 61/025 Reverse osmosis; Hyperfiltration
• CPC Class Codes: B01D 61/027 Nanofiltration
• CPC Class Codes: B01D 67/0093 Chemical modification
• CPC Class Codes: B01D 71/56 Polyamides, e.g. polyester-amides
• CPC Class Codes: B01D 71/66 Polymers having sulfur in the main chain, with or without nitrogen, oxygen or carbon only
• CPC Class Codes: C01F 7/473 Removal of organic compounds, e.g. sodium oxalate
• CPC Class Codes: C08G 69/46 Post-polymerisation treatment
• CPC Class Codes: C23F 1/46 Regeneration of etching compositions

Abstract

The invention provides methods for purifying caustic feed streams using membranes that comprise polysulfonamide matrices.

Claims

1. A method comprising contacting a membrane comprising a polysulfonamide matrix with a feed solution having a pH of at least about 11 , so that the feed solution is fractionated into a permeate and into a retentate, wherein the polysulfonamide matrix comprises, 1) an insoluble branched condensation polymer matrix comprising reactant residues, and 2) a plurality of aryl residues that differ from said reactant residues and that are terminally-linked to the insoluble branched condensation polymer matrix through sulfonamide bonds.

2. The method of claim 1 wherein the membrane comprises a primary polysulfonamide polymer.

3. The method of claim 1 wherein the feed solution comprises at least 5.0 moles of titratable alkali per liter.

4. The method of claim 1 wherein the feed solution comprises at least one impurity that is concentrated in the retentate.

5. The method of claim 4 wherein the membrane rejects at least 50% of the impurity following at least 48 hours of contact with the feed solution.

6. The method of claim 4 wherein the membrane rejects at least 50% of the impurity following at least 5 days of contact with the feed solution.

7. The method of claim 4 wherein the impurity is a humic substance.

8. The method of claim 1 wherein the membrane, after soaking in a solution comprising 6.25 molar titratable alkali at 65°

C. for 7 days, possesses a flux of at least 3 LMH at 400 psi and demonstrates at least 80% rejection of sodium humate as measured by UV-Vis spectrometry at 400 nm; and

wherein the feed solution comprises a) 6.25 molar titratable alkali, and b) at least 1 gram/liter of dissolved sodium humate.

9. The method of claim 1 wherein the membrane, after soaking in a solution comprising 6.25 molar titratable alkali at 65°

C. for 30 days, possesses a flux of at least 3 LMH at 400 psi and demonstrates at least 80% rejection of sodium humate as measured by UV-Vis spectrometry at 400 nm; and

wherein the feed solution comprises a) 6.25 molar titratable alkali, and b) at least 1 gram/liter of dissolved sodium humate.

10. The method of claim 1 wherein the feed solution is a Bayer process liquor.

11. The method of claim 10 wherein the membrane is part of a spiral wound module.

12. The method of claim 10 wherein the permeate is recycled in a closed loop Bayer process.

13. The method of claim 1 wherein the feed solution is associated with a caustic etching bath, or with paper production.

14. The method of claim 1 wherein the membrane is present on the surface of porous hollow fibers.

15. The method of claim 1 wherein the membrane is a nanofiltration membrane.

16. The method of claim 1 wherein the membrane is a reverse-osmosis membrane.

17. The method of claim 1 wherein each aryl residue is an aryl group that is optionally substituted with one or more substituents independently selected from cyano, halo, hydroxy, mercapto, nitro, carboxy, sulfo, (C₁-C₂₀)alkyl, (C₁-C₂₀)alkoxy, (C₁-C₂₀)alkoxycarbonyl, (C₁-C₂₀)alkanoyloxy, or —

NR_aR_b, wherein R_a and R_b may be the same or different and are chosen from hydrogen (C₁-C₂₀)alkyl, (C₁-C₂₀)alkoxy, (C₁-C₂₀)alkoxycarbonyl, and (C₁-C₂₀)alkanoyloxy, or wherein R_a and R_b together with the nitrogen to which they are attached form a pyrrolidino, piperidino, morpholino, or thiomorpholino ring;

wherein each (C₁-C₂₀)alkyl, (C₁-C₂₀)alkoxy, (C₁-C₂₀)alkoxycarbonyl, and (C₁-C₂₀)alkanoyloxy is optionally substituted with one or more cyano, halo, hydroxy, mercapto, nitro, carboxy, sulfo, oxo (═

O), thioxo (═

S) or —

NR_aR_b and wherein one or more carbons of each (C₁-C₂₀)alkyl, (C₁-C₂₀)alkoxy, (C₁-C₂₀)alkoxycarbonyl, and (C₁-C₂₀)alkanoyloxy can optionally be replaced with —

O—

, —

S—

, or —

NR_c—

, wherein each R_c is independently hydrogen, (C₁-C₆)alkyl, (C₁-C₆)alkoxy, (C₁-C₆)alkoxycarbonyl, and (C₁-C₆)alkanoyloxy.

18. The method of claim 1 wherein each aryl residue is a heteroaryl group that is optionally substituted with one or more substituents independently selected from cyano, halo, hydroxy, mercapto, nitro, carboxy, sulfo, (C₁-C₂₀)alkyl, (C₁-C₂₀)alkoxy, (C₁-C₂₀)alkoxycarbonyl, (C₁-C₂₀)alkanoyloxy, or —

NR_aR_b, wherein R_a and R_b may be the same or different and are chosen from hydrogen (C₁-C₂₀)alkyl, (C₁-C₂₀)alkoxy, (C₁-C₂₀)alkoxycarbonyl, and (C₁-C₂₀)alkanoyloxy, or wherein R_a and R_b together with the nitrogen to which they are attached form a pyrrolidino, piperidino, morpholino, or thiomorpholino ring;

wherein each (C₁-C₂₀)alkyl, (C₁-C₂₀)alkoxy, (C₁-C₂₀)alkoxycarbonyl, and (C₁-C₂₀)alkanoyloxy is optionally substituted with one or more cyano, halo, hydroxy, mercapto, nitro, carboxy, sulfo, oxo (═

O), thioxo (═

S) or —

NR_aR_b and wherein one or more carbons of each (C₁-C₂₀)alkyl, (C₁-C₂₀)alkoxy, (C₁-C₂₀)alkoxycarbonyl, and (C₁-C₂₀)alkanoyloxy can optionally be replaced with —

O—

, —

S—

, or —

NR_c—

, wherein each R_c is independently hydrogen, (C₁-C₆)alkyl, (C₁-C₆)alkoxy, (C₁-C₆)alkoxycarbonyl, and (C₁-C₆)alkanoyloxy.

19. The method of claim 1 wherein the aryl residues that are terminally-linked are residues of benzenedisulfonyl chloride, naphthalene trisulfonyl chloride, or benzenetrisulfonyl chloride.

20. The method of claim 1 wherein the polysulfonamide matrix is layered or coated by interfacial polymerization on at least one side of a support material to form a composite membrane.

21. The method of claim 20 wherein the support material is an ultrafiltration membrane.

22. The method of claim 20 wherein the support material is a porous polyphenylene sulfide material.

23. The method of claim 22 wherein the composite membrane is part of a spiral wound module.

24. The method of claim 23 wherein the permeate is recycled in a closed loop Bayer process.