Electrolytic cell

• US 20020027068A1
• Filed: 04/11/2001
• Published: 03/07/2002
• Est. Priority Date: 04/13/2000
• Status: Active Grant

• Current Assignee: Elan Pharma International Limited (Perrigo Company PLC)
• Original Assignee: Elan Pharma International Limited (Perrigo Company PLC)
• Inventors: Lavi, Gilad, Yigal, Gil, Rosenblum, Maya
• Granted Patent: US 6,572,740 B2
• Time in Patent Office: Days
• US Class Current: 204/228.1
• CPC Class Codes: A61M 2005/14204 with gas-producing electrochemical cell
• CPC Class Codes: A61M 5/142 Pressure infusion, e.g. using pumps
• CPC Class Codes: C25B 9/00 Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
• CPC Class Codes: F15B 2015/208 Special fluid pressurisation means, e.g. thermal or electrolytic
• CPC Class Codes: Y02E 60/36 Hydrogen production from non-carbon containing sources, e.g. by water electrolysis

Abstract

Improved electrolytic cells are described. The cells comprise the novel electrolyte K₂HPO₄, or a less alkaline phosphate buffer solution, electrodes having a modified composition, or a combination of the new electrolyte and a modified composition electrode. The K₂HPO₄ electrolyte, or less alkaline phosphate buffer solution, and modified electrodes can be used in liquid delivery devices which deliver a liquid agent at a constant rate or a controlled variable rate over a period of time.

Claims

1. An electrolytic cell comprising:

(a) an electrolyte solution comprising K₂HPO₄, or a less alkaline phosphate buffer solution, in water; and

(b) at least two electrodes comprising an anode and a cathode, wherein;

(i) the anode is made of a material selected from the group consisting of stainless steel, nickel, and a noble metal; and

(ii) the electrodes are connectable to a source of electrical current,

wherein when the electrodes are energized by an electrical current, the current is conducted through the electrolyte resulting in a gas forming at each electrode.

2. The cell of claim 1, which provides a steady rate of gas production for up to about 200 hours or longer.

3. The cell of claim 1, which provides a steady rate of gas production for a period of time from about 1 hour to about 200 hours or longer.

4. The cell of claim 1, wherein the gas is generated at a steady rate.

5. The cell of claim 1, wherein the current is applied at a pulsatile rate and the corresponding rate of gas delivery is at a pulsatile rate.

6. The cell of claim 1, wherein the gas is generated at a rate of about 0.001 ml of gas/hour up to about 24 ml of gas/hour.

7. The cell of claim 1, wherein the anode is composed of a noble metal material selected from the group consisting of platinum, a platinum alloy, rhodium, a rhodium alloy, osmium, an osmium alloy, ruthenium, a ruthenium alloy, gold, a gold alloy, iridium, and an iridium alloy, wherein such alloys do not contain metals which are soluble in anodic dissolution.

8. The cell of claim 1, which has a Faradaic current efficiency selected from the group consisting of at least 50%, at least 75%, at least 80%, at least 85%, at least 90%, and at least 95%.

9. The cell of claim 1, wherein the electrolyte is present at a concentration of at least 1 M up to about 6 M.

10. The cell of claim 1, wherein:

(a) the electrolyte is present at a concentration of about 1 to about 6 M and in an amount of from about 0.15 ml to about 100 L;

(b) the electrodes comprise stainless steel and have a surface area of about 0.19 cm² to about 50 cm² or more;

(c) the current is less than or equal to about 2 mA; and

(d) the gas is generated at a steady rate or at a pulsatile rate and is produced at a rate of from about 0.01 ml of gas/hr up to about 1.5 ml of gas/hour.

11. The cell of claim 1, wherein:

(a) the electrolyte is present at a concentration of about 1 to about 3 M and in an amount of from about 0.2 ml to about 100 L

(b) the electrodes comprise stainless steel and have a surface area of about 0.19 cm² to about 50 cm² or more;

(c) the current is about 7 mA or greater, and

(d) the gas is generated at a steady rate or at a pulsatile rate and is produced at a rate of at least 4 ml of gas/hour.

13. The cell of claim 12, wherein the gas is formed at a controlled variable rate.

14. The cell of claim 12 which provides a controlled variable rate of gas production for a period of from about 1 to about 110 hours or more.

15. The cell of claim 12, which provides an initial high rate of gas production for a period of from about 4 to about 15 hours.

16. The cell of claim 12, wherein the anode is composed of a material selected from the group consisting of brass and copper.

17. The cell of claim 12, wherein the gas is generated at a rate of about 0.001 ml of gas/hour up to about 24 ml of gas/hour.

18. The cell of claim 12, wherein the electrolyte is present at a concentration of from about 1 to about 6 M.

19. The cell of claim 12, wherein:

(a) the electrolyte is present at a concentration of about 1 to about 6 M and in an amount of from about 0.15 ml to about 100 L;

(b) the anode comprises copper or brass;

(c) the electrodes have a surface area of about 0.19 cm² to about 50 cm²;

(d) the current is less than or equal to about 2 mA; and

(e) the gas is generated at a rate of from about 0.001 ml of gas/hr up to about 1.5 ml of gas/hour.

20. The cell of claim 12, wherein:

(a) the electrolyte is present at a concentration of about 1 to about 3 M and in an amount of from about 0.2 ml to about 100 L;

(b) the anode comprises copper or brass;

(c) the electrodes have a surface area of about 0.19 cm² to about 50 cm²;

(d) the current is about 7 mA or greater; and

(e) the gas is generated at a rate of about 0.01 ml of gas/hr up to about 24 ml of gas/hr.

21. A device for dispensing a liquid at a predetermined rate, comprising an electrolytic cell according to claim 10.

22. A device for dispensing a liquid at a predetermined rate, comprising an electrolytic cell according to claim 11.

23. A device for dispensing a liquid at a predetermined rate, comprising an electrolytic cell according to claim 19.

24. A device for dispensing a liquid at a predetermined rate, comprising an electrolytic cell according to claim 20.

25. A device for dispensing a liquid at a predetermined rate, comprising an electrolytic cell according to claim 1.

26. The device of claim 25, further including an electrical power supply for energizing said electrodes.

27. The device of claim 26, wherein said power supply includes a battery and an electrical control circuit for controlling the current of energization of the electrode, and thereby the rate of dispensing the liquid from the container.

28. The device of claim 27, wherein said electrical control circuit includes presettable means for presetting the rate of energization of the electrodes, and an electrical switch for controlling the energization of the electrodes.

29. The device of claim 25, wherein the electrodes are composed of a material selected from the group consisting of platinum, a platinum alloy, rhodium, a rhodium alloy, iridium, an iridium alloy, osmium, an osmium alloy, ruthenium, a ruthenium alloy, gold, and a gold alloy, wherein such alloys do not contain metals which are soluble in anodic dissolution.

30. The device of claim 25, wherein the electrolytic cell has a Faradaic current efficiency selected from the group consisting of at least 50%, at least 75%, at least 80%, at least 85%, at least 90%, and at least 95%.

31. A device for dispensing a liquid at a controlled variable rate comprising according to claim 12.

32. The device of claim 31, further including an electrical power supply for energizing said electrodes.

33. The device of claim 32, wherein said power supply includes a battery and an electrical control circuit for controlling the rate of energization of the electrode, and thereby the rate of dispensing the liquid from the container.

34. The device of claim 33, wherein said electrical control circuit includes presettable means for presetting the rate of energization of the electrodes, and an electrical switch for controlling the energization of the electrodes.

35. The device of claim 31, wherein the anode is composed of a material selected from the group consisting of brass and copper.

36. The electrolytic cell of claim 1, wherein at least the anode is stainless steel, which is pretreated in a process comprising:

(a) washing the electrodes in a solution of ethyl alcohol;

(b) rinsing the electrodes in deionized or RO water;

(c) dipping the electrodes in a solution of about 5% citric acid in deionized or RO water at an elevated temperature for about 30 to about 40 minutes;

(d) rinsing the electrodes in deionized or RO water; and

(e) storing the electrodes in K₂HPO₄ solution.

37. The electrolytic cell of claim 1, wherein at least the anode is nickel, which is pretreated in a process comprising:

(a) washing the electrodes in a solution of ethyl alcohol;

(b) rinsing the electrodes in deionized or RO water;

(c) dipping the electrodes in a solution selected from the group consisting of (i) citric acid, ammonium acetate, and EDTA at an acidic pH;

(ii) citric acid, ethylenediamine, and a reducing agent; and

(iii) ammonium nitrate, citric acid, triethanolamine, and a reducing agent;

(d) rinsing the electrodes in deionized or RO water; and

(e) storing the electrodes in K₂HPO₄ solution.

38. The electrolytic cell of claim 12, wherein at least the anode is copper, which is pretreated in a process comprising:

(a) washing the electrodes in a solution of ethyl alcohol;

(b) rinsing the electrodes in deionized or RO water;

(c) dipping the electrodes in a solution of about 5% citric acid in deionized or RO water for about 15 to about 20 minutes;

(d) rinsing the electrodes in deionized or RO water; and

(e) storing the electrodes in K₂HPO₄ solution.

39. The electrolytic cell of claim 12, wherein at least the anode is brass, which is pretreated in a process comprising:

(a) washing the electrodes in a solution of ethyl alcohol;

(b) rinsing the electrodes in deionized or RO water;

(c) dipping the electrodes in a solution of about 5% citric acid in deionized or RO water for about 5 to about 10 minutes;

(d) rinsing the electrodes in deionized or RO water; and

(e) storing the electrodes in K₂HPO₄ solution.

12. An electrolytic cell comprising:

(a) an electrolyte solution comprising K₂HPO₄, or a less alkaline phosphate buffer solution, in water; and

(b) at least two electrodes comprising an anode and a cathode, wherein;

(i) the electrodes are made of a conductive material;

(ii) the anode is electrochemically soluble; and

(iii) the electrodes are connectable to a source of electrical current,

wherein when the electrodes are energized by an electrical current, the current is conducted through the electrolyte resulting in a gas forming at one or more of the electrodes.