Electrode and electrolytic cell containing same

• US 5,989,396 A
• Filed: 04/01/1998
• Issued: 11/23/1999
• Est. Priority Date: 04/02/1997
• Status: Expired due to Term

• Current Assignee: Eltech Systems Corporation (Industrie De Nora S.p.A)
• Original Assignee: Eltech Systems Corporation (Industrie De Nora S.p.A)
• Inventors: Mitchell, Thomas A., Carlson, Richard C., Ernes, Lynne M., Prasnikar, Albert R., Coin, Richard J., Lezan, Catherine M.
• Primary Examiner(s): Bell, Bruce F.
• Application Number:
  US09/053,154
• Time in Patent Office: 601 Days
• Field of Search: 204/290 F, 204/290 R, 204/291, 204/293, 427/77, 427/115, 427/126.3, 427/126.5, 29/623.1, 205/8220, 205/225, 205/229, 205/322, 205/333
• US Class Current: 204/252
• CPC Class Codes: B01D 19/0068 General arrangements, e.g. flowsheets B01D19/0063 takes precedence
• CPC Class Codes: C02F 1/001 Processes for the treatment of water whereby the filtration technique is of importance C02F1/44 takes precedence; construction of filters in general B01D24/00 - B01D41/00
• CPC Class Codes: C02F 1/4606 for producing oligodynamic substances to disinfect the water
• CPC Class Codes: C02F 1/46104 Devices therefor; Their operating or servicing
• CPC Class Codes: C02F 1/46109 Electrodes
• CPC Class Codes: C02F 1/4674 with halogen or compound of halogens, e.g. chlorine, bromine
• CPC Class Codes: C02F 2001/46128 Bipolar electrodes
• CPC Class Codes: C02F 2001/46142 Catalytic coating
• CPC Class Codes: C02F 2001/46152 characterised by the shape or form electrodes in particulate form or with conductive or non-conductive particles between them C02F1/46114
• CPC Class Codes: C02F 2201/4612 Controlling or monitoring
• CPC Class Codes: C02F 2201/4618 Supplying or removing reactants or electrolyte
• CPC Class Codes: C02F 2209/006 comprising a software program or a logic diagram
• CPC Class Codes: C02F 2301/043 Treatment of partial or bypass streams
• CPC Class Codes: C02F 2303/04 Disinfection
• CPC Class Codes: C25B 11/091 consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds
• CPC Class Codes: C25B 11/093 at least one noble metal or noble metal oxide and at least one non-noble metal oxide

Abstract

An electrode is disclosed having a coating on part of the electrode, e.g., a front face, comprising the oxides of tin, antimony, at least one platinum group metal and at least one valve metal. Another part of the electrode, such as a back face, has a coating comprising the oxides of at least one valve metal and at least one platinum group metal. The electrode can be generally plate-shaped and most desirably has at least one chamfered corner. The electrode is particularly useful in a cell wherein brine electrolyte is electrolyzed to prepare a disinfectant solution containing hypochlorite. The disinfectant solution can be especially serviceable, such as in maritime application, for treating water, e.g., freshwater as represented by desalinated water.

Claims

1. An electrode comprising a metal member having an anodic coating on a surface area of said member, which coating comprises the oxides of tin, antimony, at least one platinum group metal, and at least one valve metal, and having a cathodic coating on a surface area of said member that is not the surface area of said anodic coating, which cathodic coating comprises the oxides of at least one valve metal and at least one platinum group metal.

2. The electrode of claim 1 wherein said metal member is a plates member, said plate member has front and back major faces, at least two sets of opposed parallel edges, and said anodic coating is present on one major face and said cathodic coating is present on the other major face.

3. The electrode of claim 2 wherein said major face is connected with a current distributor means for said electrode.

4. The electrode of claim 1 wherein said metal member is a non-perforate, solid and inflexible metal member, said anodic coating is present on a first zone of a major face of said member and said cathodic coating is present on a second zone of the same major face.

5. The electrode of claim 1 wherein said metal member is a cylindrical member having inner and outer major faces.

6. The electrode of claim 1 wherein said metal member is of a metal selected from the group consisting of titanium, tantalum, niobium, zirconium, their alloys, and intermetallic mixtures thereof.

7. The electrode of claim 1 wherein said anodic coating contains the oxides of tin, antimony, iridium and titanium, and said cathodic coating contains the oxides of one or more of ruthenium and iridium as well as the oxide of titanium.

8. The electrode of claim 7 wherein said anodic coating contains from about 30 to about 90 weight percent stannic oxide and from about 1.0 to about 25 weight percent antimony oxide, while having the oxides of tin and antimony in a mole ratio of tin to antimony of between about 99:

1 and about 70;

30.

9. The electrode of claim 8 wherein said coatings coat a surface of said metal member comprising one or more of a metallic surface or an intermediate layer on said metallic surface.

10. The electrode of claim 9 wherein said intermediate layer comprises a layer on said metal member containing a metal oxide.

11. The electrode of claim 7 wherein said cathodic coating contains from about 10 mole percent to about 45 mole percent of platinum group metal oxides.

12. The electrode of claim 11 wherein said cathode coating contains at least about 5 mole percent of each of iridium oxide and ruthenium oxide.

13. An electrolytic cell utilized in an electrolytic disinfectant system for the electrolysis of brine from a brine tank to produce hypochlorite, or for organic destruction contacting the electrode of claim 1, wherein said electrode is a bipolar electrode.

14. The electrolytic cell of claim 13 wherein said briner tank has inlet means for receiving salt and water, and outlet means for discharging brine electrolyte to said cell as well as for discharging brine to brine disposal means.

15. The method of preparing an electrode comprising an anodic coating, a cathodic coating and a substrate metal, with each coating containing metal oxides and being electrochemically active, which coatings coat said metal and are cured thereon, which method comprises:

(a) applying, to said metal for said anodic coating, but without curing applied coating, a composition comprising precursor substituents for oxides of tin, antimony, at least one platinum group metal and at least one valve metal;

(b) applying, to said metal for said cathodic coating, but without curing applied coating, a composition comprising precursor substituents for oxides of at least one valve metal and at least one platinum group metal;

(c) simultaneously drying applied anodic and cathodic coating precursor substituents, providing dry anodic coating and dry cathodic coatings;

(d) applying to said dry anodic coating additional composition of said precursor substituents for said anodic coating, without curing said additional composition;

(e) applying to said dry cathodic coating additional composition of said precursor substituents for said cathodic coating, without curing said additional composition;

(f) simultaneously drying additional applied anodic and cathodic coating precursor substituents, providing additional dry anodic coating and cathodic coating; and

(g) simultaneously curing all applied anodic coating precursor substituents and all applied cathodic coating precursor substituents on said substrate metal.

16. The method of preparing an electrode comprising an anodic coating, a cathodic coating and a substrate metal, with each coating containing metal oxides and being electrochemically active, which coatings coat said metal and are cured thereon, which method comprises:

(a) applying, to said metal for said anodic coating, but without curing applied coating, a composition comprising precursor substituents for oxides of tin, antimony, at least one platinum group metal and at least one valve metal;

(b) applying, to said metal for said cathodic coating, but without curing applied coating, a composition comprising precursor substituents for oxides of at least one valve metal and at least one platinum group metal; and

(c) simultaneously curing said applied anodic coating precursor substituents and said applied cathodic coating precursor substituents on said substrate metal.

17. The method of claim 16 wherein the applying of precursor substituents for said cathodic coating and said anodic coating comprises the applying of one or more of metal chloride or sulfate salts.

18. The method of claim 16 further comprising simultaneously drying applied anodic and cathodic coating precursor substituents, before curing, then applying at least one further coating of each of said anodic and cathodic coating precursor substituents onto the dry coatings and simultaneously drying the further applied coatings before curing.

19. The method of claim 18 wherein said drying proceeds at a temperature within the range from about 90°

F. to about 120°

F. for a time of from about one minute to about five minutes.

20. The method of claim 16 wherein said curing proceeds by baking at a temperature within the range from about 450°

F. to about 650°

F. for a time of from about five minutes to about thirty minutes.

21. The method of claim 16 wherein said precursor substituents are applied directly to a metallic surface of said substrate metal, or are applied over an intermediate layer on said substrate metal.

22. A generally plate-shaped electrode having front and back major faces and an edge, which electrode has an at least substantially rectangular shaped front major face and back major face and which edge has at least one chamfered corner.

23. The electrode of claim 22 wherein said front and back major faces are at least substantially planar.

24. The electrode of claim 22 wherein at least one of said front and back major faces is coated.

25. The electrode of claim 24 wherein said electrode comprises a metal substrate having an electrocatalytic coating.

26. The electrode of claim 25 wherein said metal substrate is a non-perforate, solid and inflexible metal substrate.

27. The electrode of claim 25 wherein the metal of said substrate is a valve metal selected from the group consisting of titanium, tantalum, zirconium, niobium, their alloys and intermetallic mixtures.

28. The electrode of claim 25 wherein said electrocatalytic coating contains a platinum group metal, or metal oxide or their mixtures.

29. The electrode of claim 28 wherein said electrocatalytic coating contains at least one oxide selected from the group consisting of platinum group metal oxides, magnetite, ferrite, cobalt oxide spinel, and tin oxide, and/or contains a mixed crystal material of at least one oxide of a valve metal and at least one oxide of a platinum group metal, and/or contains one or more of manganese dioxide, lead dioxide, platinate substituent, nickel-nickel oxide or a mixture of nickel plus lanthanum oxides.

30. The electrode of claim 22 wherein said electrode is a bipolar electrode having an anode coating on one major face and a cathode coating on another major face.

31. The electrode of claim 30 wherein the anode coating for said bipolar electrode contains oxides of tin, antimony, at least one platinum group metal and at least one valve metal, and the cathode coating for said bipolar electrode comprises the oxides of at least one valve metal and at least one platinum group metal.

32. The electrode of claim 31 wherein said anode coating includes the oxides of tin, antimony, iridium and titanium, and said cathode coating includes the oxides of one or more of ruthenium and iridium as well as the oxide of titanium.

33. The electrode of claim 32 wherein said anodic coating contains from about 30 to about 90 weight percent stannic oxide and from about 1.0 to about 25 weight percent antimony oxide, while having the oxides of tin and antimony in a mole ratio of tin to antimony of between about 99:

1 and about 70;

30.

34. The electrode of claim 32 wherein said cathode coating contains from about 10 mole percent to about 45 mole percent of platinum group metal oxides.

35. The electrode of claim 34 wherein said cathode coating contains at least about 5 mole percent of each of iridium oxide and ruthenium oxide.

36. An electrolytic cell utilized for the electrolysis of brine to produce hypochlorite, or for organic destruction contacting the electrode of claim 22, wherein said electrode is a bipolar electrode.

37. An electrolytic cell containing the bipolar electrode of claim 36.