METHOD OF GENERATING ENHANCED BIOCIDAL ACTIVITY IN THE ELECTROYLSIS OF CHLORINE CONTAINING SOLUTIONS AND THE RESULTING SOLUTIONS

• US 3,616,355 A
• Filed: 08/05/1968
• Issued: 10/26/1971
• Est. Priority Date: 08/05/1968
• Status: Expired due to Term

• Current Assignee: Ross M. Gwynn, Tim Themy
• Original Assignee: Ross M. Gwynn, Tim Themy
• Inventors: Themy, Tim, Gwynn, Ross M.
• Primary Examiner(s): Tung, T.
• Application Number:
  US04/750,017
• Time in Patent Office: 1,177 Days
• Field of Search: 204/95,98,99,128,129,149-152,29F
• US Class Current: 205/701
• CPC Class Codes: C01B 13/10 Preparation of ozone
• CPC Class Codes: C02F 1/4672 by electrooxydation
• CPC Class Codes: C02F 1/4674 with halogen or compound of halogens, e.g. chlorine, bromine

Abstract

An aqueous medium or dilute brine containing about 10 p.p.m. to 21,000 p.p.m. of chloride ion, and essentially free of other halogen, is electrolyzed between spaced electrodes, with the exposed surface of at least the anode being a continuous surface of a platinum metal, at a minimum potential in the general range of about 10 volts for a 21,000 p.p.m. medium to 100 volts for a 10 p.p.m. medium, and current density below about 5 amps per square inch of electrode surface, with the effluent medium at a temperature in the range of about 55* to 95* F. and preferably about 60* to 75* F., and at a pH within the range 6 to 8.5 to thereby generate in said medium chlorine together with free radicals and other oxidizing species including ozone, said ozone being present in an amount to provide at least one part by weight of ozone to each 50 parts by weight of available chlorine in said effluent. Narrowing the pH range, adjusting the effluent temperature and increasing the voltage may increase the proportion of ozone. At a pH of 7 to 8, a temperature in excess of 60* F., and a potential about 25 percent above the minimum for a particular chloride ion concentration, the proportion of ozone to chlorine is generally in excess of one part ozone to 20 parts chlorine; and at a pH of 7.2-7.8, a temperature in excess of about 66* F. and a potential about 50 percent above said minimum this proportion may be as high as one part ozone to five or ten parts chlorine. Chloride is suitably supplied as NaC1 solution in varying concentrations in the fractional normality range, preferably about 0.003 N to 0.6 N corresponding with about 10 p.p.m. to 21,000 p.p.m. of chloride ion.

Claims

2. The process as defined in claim 1 wherein said minimum potential is within the general range of about 10 volts for a 21, 000 p.p.m. medium to about 100 volts for a 10 p.p.m. medium.

3. A biocidally active aqueous medium obtained by the process as defined in claim 2.

4. The process as defined in claim 2 wherein the electrode potential is about 25 percent above the minimum value for a particular chloride ion concentration, the pH is in the range of 7 to 8, the effluent temperature is in the range of 60* to 75* F., and the ozone is present in the effluent in the proportion of at least 1 part to each 20 parts by weight of chlorine.

5. The process as defined in claim 4 wherein the electrode potential is about 50 percent above the minimum value for a particular chloride ion concentration, the pH is in the range of 7.2 to 7.8, , the effluent temperature is in excess of 65* F., and the ozone may be present in the effluent in proportions as high as 1 part ozone to each 5 to 10 parts by weight of chlorine.

6. The process as defined in claim 1 wherein said aqueous medium is a sodium chloride solution having a normality within the range of about 0.0003N to 0.6 + or - N.

7. The process as defined in claim 1 wherein the aqueous medium is passed between spaced electrodes at a predetermined voltage and the extent of electrolysis is essentially proportional to the flow rate of the medium.

8. The process as defined in claim 7 wherein a portion only of a main stream of aqueous medium is diverted from the main stream and after being electrolyzed between said spaced electrodes is recombined with said main stream.

9. The process as defined in claim 8 wherein the cHloride content of said diverted portion is supplemented before passing said diverted portion between said spaced electrodes.

10. The process as defined in claim 1 wherein a fixed quantity of the aqueous medium is exposed to the electrodes, and the extent of electrolysis is essentially proportional to the duration of the application of voltage across the electrodes.

11. The process as defined in claim 1 wherein a medium containing about 10 to 200 p.p.m. of chloride ion is electrolyzed at a potential within the general range at least 100 volts with a 10 p.p.m. medium to at least 20 volts with a 200 p.p.m. medium, said process being particularly adapted to the treatment of natural, chloride containing aqueous media.

12. The process as defined in claim 1 wherein a medium containing about 200 to 3,000 p.p.m. of chloride ion is electrolyzed at a potential within the general range of at least 20 volts with a 200 p.p.m. medium to at least 14 volts with a 3, 000 p.p.m. medium, said process being particularly adapted for the treatment of aqueous media in which the chloride ion content has been supplemented by the addition of water soluble chloride.

13. The process as defined in claim 1 wherein a medium containing about 3,000 to 21,000 p.p.m. of chloride ion is electrolyzed at a potential within the general range of at least 14 volts with a 3,000 p.p.m. medium to at least 10 volts with a 21,000 p.p.m. medium, said process being particularly adapted to the treatment of water enriched with chloride ion for combination with other aqueous media in the chlorination thereof.