Microorganism-removing filter medium having high isoelectric material and low melt index binder

• US 7,303,683 B2
• Filed: 06/29/2004
• Issued: 12/04/2007
• Est. Priority Date: 04/04/2003
• Status: Active Grant

• Current Assignee: Clorox Company
• Original Assignee: Clorox Company
• Inventors: Cumberland, Scott L.
• Primary Examiner(s): HOPKINS, ROBERT A
• Application Number:
  US10/880,625
• Publication Number:
  US 20040251190A1
• Time in Patent Office: 1,253 Days
• Field of Search: 210/660, 210/764, 210/266, 210/263, 502/416, 502/417, 502/427
• US Class Current: 210/660
• CPC Class Codes: B01D 2239/0407 comprising particulate additives, e.g. adsorbents apparatus incorporating gas filtering material B01D46/0036
• CPC Class Codes: B01D 2239/0442 Antimicrobial, antibacterial, antifungal additives apparatus incorporating such gas filtering material B01D46/0028
• CPC Class Codes: B01D 2239/086 Binders between particles or fibres
• CPC Class Codes: B01D 2239/1216 Pore size
• CPC Class Codes: B01D 2239/1291 Other parameters
• CPC Class Codes: B01D 39/2062 Bonded, e.g. activated carbon blocks
• CPC Class Codes: Y02W 10/37 using solar energy

Abstract

A filter medium capable of removing microorganisms from a fluid such as water. The filter medium includes particles of activated carbon, particles of a substantially insoluble inorganic material having an isoelectric point greater than the fluid being filtered. A low melt index binder, preferably with a melt index of less than about 1 gram per 10 minutes, binds the particles of activated carbon and particles of inorganic material, such that the binder will become tacky at elevated temperatures without becoming sufficiently liquid to substantially wet the particles of activated carbon and inorganic material. An antimicrobial material can be incorporated into the filter to prevent biofilm growth. The use of a biocidal material in combination with the high isoelectric point material provides a trap-and-kill mechanism for microorganism removal.

Claims

1. A filter medium capable of removing microorganisms from a fluid, comprising:

particles of activated carbon;

particles of a substantially insoluble inorganic material having an isoelectric point greater than a pH of a fluid being filtered;

a binder for binding the particles of activated carbon and particles of inorganic material;

wherein a first portion of the particles of inorganic material have a first mean particle size distribution and a second portion of the particles of inorganic material have a second mean particle size distribution, the first mean particle size distribution being larger than the second mean particle size distribution, and

wherein the filter medium is formed in a block or sheet.

2. A filter medium as recited in claim 1, wherein the inorganic material is a magnesium containing material.

3. A filter medium as recited in claim 2, wherein the inorganic material is magnesium hydroxide.

4. A filter medium as recited in claim 1, wherein the inorganic material has an isoelectric point greater than about 9 pH.

5. A filter medium as recited in claim 1, wherein the inorganic material has an isoelectric point greater than about 10 pH.

6. A filter medium as recited in claim 1, wherein the inorganic material is present in an amount between about 25 weight percent to about 45 weight percent of the total weight of the filter medium.

7. A filter medium as recited in claim 1, wherein the binder is an ultra high molecular weight polymer having a molecular weight greater than about 4 million.

8. A filter medium as recited in claim 1, wherein the binder is ultra high molecular weight polyethylene.

9. A filter medium as recited in claim 1, wherein the binder has a melt index of less than about 1 gram per 10 minutes as determined by ASTM D1238 at 190 degrees C. and 15 kilograms load.

10. A filter medium as recited in claim 1, wherein the melt index of the binder is less than about 0.1 grams per 10 minutes as determined by ASTM D1238 at 190 degrees C. and 15 kilograms load.

11. A filter medium as recited in claim 1, wherein the binder is present in an amount between about 20 weight percent to about 35 weight percent of the total weight of the filter medium.

12. A filter medium as recited in claim 1, wherein 75 grams of the filter medium performs a greater than 1×

10⁴ plaque forming units/milliliter reduction of viruses after 100 gallons of water passes through the filter medium.

13. A filter medium as recited in claim 1, wherein the filter medium is cylindrically shaped with an outer diameter of less than about 4 inches and a maximum length between ends of the filter medium of less than about 3 inches.

14. A filter medium as recited in claim 13, wherein the filter medium performs a greater than 1×

10⁴ plaque forming units/milliliter reduction of viruses after 100 gallons of water passes through the filter medium.

15. A filter medium as recited in claim 1, wherein a mean pore size of pores formed by the particles and binder is between about 0.01 micron and about 10 microns.

16. A filter medium as recited in claim 1, wherein a mean pore size of pores formed by the particles and binder is between about 0.1 micron and about 1 microns.

17. A filter medium as recited in claim 1, wherein the first mean particle size distribution is at least about twice as large as the second mean particle size distribution.

18. A filter medium as recited in claim 1, wherein the first mean particle size distribution is greater than about 10 μ

m, and the second mean particle size distribution is less than about 10 μ

ms.

19. A filter medium as recited in claim 1, wherein the first portions of the particles of inorganic material are present at about 85% or more by weight based on a total weight of the inorganic material.

20. A filter medium as recited in claim 1, further comprising at least one additional adsorptive material other than the activated carbon and inorganic material.

21. A filter medium as recited in claim 1, wherein the fluid is water.

22. A filter medium as recited in claim 1, wherein a percentage concentration of an inorganic cation provided by the inorganic material times pressure drop through the filter medium in pounds per square inch is at least about 0.5 [g Mg·

lb]/[g filter·

in²].

23. A method for removing microorganisms from a fluid, comprising causing the fluid to flow through the filter medium of claim 1.

24. A device for removing microorganisms from a fluid, comprising a water dispenser implementing the filter medium of claim 1.

25. A device for removing microorganisms from air, comprising the filter medium of claim 1.

26. A filter medium capable of removing microorganisms from a fluid, comprising:

particles of activated carbon;

particles of magnesium hydroxide present at about 40% to about 50% by weight; and

a binder for binding the particles of activated carbon and inorganic material, the binder having a melt index of less than about 1 gram per 10 minutes as determined by ASTM D1238 at 190 degrees C. and 15 kilograms load, and

wherein the filter medium is formed in a block or sheet.

27. A filter medium capable of removing microorganisms from a fluid, comprising:

particles of activated carbon;

particles of a substantially insoluble inorganic material having an isoelectric point greater than a pH of a fluid being filtered;

a binder for binding the particles of activated carbon and particles of inorganic material;

an antimicrobial material, and

wherein the filter medium is formed from a block or sheet.

28. A filter medium as recited in claim 27, wherein the inorganic material is a magnesium containing material.

29. A filter medium as recited in claim 28, wherein the inorganic material is magnesium hydroxide.

30. A filter medium as recited in claim 27, wherein the inorganic material has an isoelectric point greater than about 9 pH.

31. A filter medium as recited in claim 27, wherein the inorganic material has an isoelectric point greater than about 10 pH.

32. A filter medium as recited in claim 27, wherein the inorganic material is present in an amount between about 25 weight percent to about 45 weight percent of the total weight of the filter medium.

33. A filter medium as recited in claim 27, wherein the binder is an ultra high molecular weight polymer having a molecular weight greater than about 4 million.

34. A filter medium as recited in claim 27, wherein the binder is ultra high molecular weight polyethylene.

35. A filter medium as recited in claim 27, wherein the binder has a melt index of less than about 1 gram per 10 minutes as determined by ASTM D1238 at 190 degrees C. and 15 kilograms load.

36. A filter medium as recited in claim 27, wherein the melt index of the binder is less than about 0.1 grams per 10 minutes as determined by ASTM D1238 at 190 degrees C. and 15 kilograms load.

37. A filter medium as recited in claim 27, wherein the binder is present in an amount between about 20 weight percent to about 35 weight percent of the total weight of the filter medium.

38. A filter medium as recited in claim 27, wherein 75 grams of the filter medium performs a greater than 1×

10⁴ plaque forming units/milliliter reduction of viruses after 100 gallons of water passes through the filter medium.

39. A filter medium as recited in claim 27, wherein the filter medium is cylindrically shaped with an outer diameter of less than about 4 inches and a maximum length between ends of the filter medium of less than about 3 inches.

40. A filter medium as recited in claim 39, wherein the filter medium performs a greater than 1×

10⁴ plaque forming units/milliliter reduction of viruses after 100 gallons of water passes through the filter medium.

41. A filter medium as recited in claim 27, wherein a mean pore size of pores formed by the particles and binder is between about 0.01 micron and about 10 microns.

42. A filter medium as recited in claim 27, wherein a mean pore size of pores formed by the particles and binder is between about 0.1 micron and about 1 microns.

43. A filter medium as recited in claim 27, wherein a first portion of the particles of inorganic material have a first mean particle size distribution and a second portion of the particles of inorganic material have a second mean particle size distribution, the first mean particle size distribution being larger than the second mean particle size distribution.

44. A filter medium as recited in claim 43, wherein the first mean particle size distribution is at least about twice as large as the second mean particle size distribution.

45. A filter medium as recited in claim 43, wherein the first mean particle size distribution is greater than about 10 μ

m, and the second mean particle size distribution is less than about 10 μ

ms.

46. A filter medium as recited in claim 43, wherein the first portions of the particles of inorganic material are present at about 85% or more by weight based on a total weight of the inorganic material.

47. A filter medium as recited in claim 27, wherein the antimicrobial material is a silver-containing material.

48. A filter medium as recited in claim 47, wherein the antimicrobial material is a water-soluble silver-containing material.

49. A filter medium as recited in claim 48, wherein the antimicrobial material is selected from a group consisting of silver-impregnated zeolite and silver-impregnated zirconium phosphate.

50. A filter medium as recited in claim 47, wherein the antimicrobial material is a water-insoluble silver-containing material.

51. A filter medium as recited in claim 27, wherein the antimicrobial material is a polymeric matrix impregnated with a water-insoluble antimicrobial compound.

52. A filter medium as recited in claim 27, further comprising at least one additional adsorptive material other than the activated carbon and inorganic material.

53. A filter medium as recited in claim 27, wherein the fluid is water.

54. A filter medium as recited in claim 27, wherein a percentage concentration of an inorganic cation provided by the inorganic material times pressure drop through the filter medium in pounds per square inch is at least about 0.5 [g Mg·

lb]/[g filter·

in²].

55. A method for removing microorganisms from a fluid, comprising causing the fluid to flow through the filter medium of claim 27.

56. A device for removing microorganisms from a fluid, comprising a water dispenser implementing the filter medium of claim 27.

57. A device for removing microorganisms from air, comprising the filter medium of claim 27.

58. A water dispenser, comprising:

a bottle receiving portion for receiving a bottle of water;

a filtration portion for filtering water received from the bottle, the filtration portion including a filter medium, wherein the filter medium is formed in a block or sheet; and

comprises

particles of activated carbon;

particles of a substantially insoluble inorganic material having an isoelectric point greater than a pH of a fluid being filtered; and

a binder for binding the particles of activated carbon and particles of inorganic material, the binder having a melt index of less than about 1 gram per 10 minutes as determined by ASTM D1238 at 190 degrees C. and 15 kilograms load; and

a filtered water outlet.