Sterilization of liquids using plasma glow discharge

• US 5,876,663 A
• Filed: 11/12/1996
• Issued: 03/02/1999
• Est. Priority Date: 11/14/1995
• Status: Expired due to Term

• Current Assignee: The University Of Tennessee Research Corporation (University of Tennessee)
• Original Assignee: The University Of Tennessee Research Corporation (University of Tennessee)
• Inventors: Laroussi, Mounir
• Primary Examiner(s): Housel, James C.
• Assistant Examiner(s): Bui, Phuong T.
• Application Number:
  US08/747,091
• Time in Patent Office: 840 Days
• Field of Search: 204/164, 422/21, 422/22, 422/23, 422/28, 422/41, 426/237, 210/764, 315/111.21, 428/224
• US Class Current: 422/23
• CPC Class Codes: A23L 3/005 by heating using irradiation or electric treatment drying or kilning A23L3/40
• CPC Class Codes: A61L 2/14 Plasma, i.e. ionised gases
• CPC Class Codes: C02F 1/30 by irradiation
• CPC Class Codes: C02F 1/4608 using electrical discharges

Abstract

A method and apparatus are disclosed for sterilization of liquids using a steady-stage glow discharge apparatus, at one atmosphere.

Claims

1. A method for sterilization of a liquid which contains microorganisms which comprises directly exposing the liquid to the plasma of a steady-state glow plasma discharge at a pressure of about one atmosphere and permitting the liquid to remain exposed to the plasma discharge for a time sufficient to kill microorganisms within the liquid, wherein the steady-state glow plasma discharge is generated using electrodes R.F. energized with an rms potential of about 1 to 5 KV at about 1 to 100 KHz.

2. The method of claim 1 wherein the microorganisms are selected from the group consisting of viruses bacteria, protozoa, yeast, and fungi.

3. The method of claim 2 wherein the microorganisms are pathogenic microorganisms.

4. The method of claim 2 wherein the liquid is exposed to the plasma discharge for a time between 10 seconds and 20 minutes.

5. The method of claim 1 wherein the liquid is a non-flowing liquid.

6. The method of claim 1 wherein the liquid is a flowing liquid.

7. The method of claim 1 wherein the depth of the liquid as it is exposed to the plasma discharge is between about 0.1 cm and 2 cm.

8. The method of claim 1 wherein the liquid to be sterilized is selected from the group consisting of water, milk, juice, beer, pharmaceutical solutions and suspensions, blood and blood products, microbiological culture media, and sewage.

9. The method of claim 1 wherein the plasma is generated by an apparatus which comprises a pair of insulated metal plate electrodes, at least one of which is insulated, which are spaced between about 0.1 and 5 cm apart in a gas selected from the group consisting of air, nitrous oxide, carbon dioxide, hydrogen peroxide, a noble gas, and mixtures thereof.

10. The method of claim 3 in which the pathogenic microorganisms are gram negative bacteria.

11. The method of claim 3 in which the pathogenic microorganisms are gram positive bacteria.

12. The method of claim 1 in which the liquid is a low viscosity liquid.

13. The method of claim 1 in which the liquid is a high viscosity liquid.

14. The method of claim 13 in which the high viscosity liquid is a gel.