GB2195536A - Bactericide compositions containing nitroimadazole salts - Google Patents

Abstract

Bactericidal compositions containing nitroimidazole salts are used to inhibit growth rate of sulfate- reducing bacteria in industrial aqueous liquids containing organic materials.

Description

SPECIFICATION Bactericide compositions containing nitroimadazole salts BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to bactericide compositions comprising nitroimadazole salts and to industrial compositions containing such bactericide compositions and to the use of bactericide compositions for inhibiting the growth of microoganisms in industrial aqueous liquids containing organic materials. More particularly, the invention relates to the use of salts of nitroimidazoles alone or in conjunction with other known bactericides for inhibiting the growth of bacteria in industrial aqeuous liquids containing organic materials.

The presence of sulfate-reducing bacteria (SRB) in liquid organic materials and aqeuous liquids containing organic materials is a serious industirial problem since such bacteria metabolize sulfates with the liberation of hydrogen sulfide thereby resulting in foul smells and corrosion caused by the liberated hydrogen sulfide. The presence of SRB in hydrocarbon streams, vegetable oils, fuel oils, lubricating oils, mineral oil-based hydraulic fluids, O/W and W/O emulsions such as are used in metal working fluids and hydraulic fluids and in aqeuous liquids containing such materials are examples of materials which are attacked by SRB.Examples of industrial liquids which are affected by the presence of SRB include paper-pulp sulfite processing fluids, industrial process waters, electroplating solutions, oilwell injection waters such as water floods, polymer floods, fracturing fluids and the like, storage tanks used to store emulsions of water and oil and the like.

Since SRB present severe odor and corrosion problems in virtually all areas of industrial processing, industry is constantly searching for more effective bactericidal materials to inhibit the growth of SRB.

2. Description of Prior Art Various materials have heretofore been used to inhibit SRB in industrial liquids. Such known bactericides include nitroimadazoles, aldehydes, isothiazolones, phenolics, heavy metal compounds, acrolein and others. All of these known bactericidal materials are effective against SRB in varying degrees but all present certain problems relating to their use. Thus, some of the materials present toxicity problems, some of the materials are very expensive to use, others present solubility problems in aqeuous liquids, others are not compatible with desired or required chemical additives and others remain as residues in water in sufficiently high concentrations to render the water toxic. Certain of the materials are quite corrosive to metals.

Insofar as the present invention is concerned, U.S.P. 2,944,061 discloses the use of salts of 2-methyl-5-nitroimidazole- 1 -ethanol(metranidazole) in the treatment of amoebic and protozoal infections. Further, U.S.P. 4,395,341 discloses the use of metranidazole as a bactericide in flood waters which are injected into oil bearing formations. Still further, UK Patent Application 2103928 discloses the use of various nitroimidazoles in inhibiting spoilage of liquid organic materials.

Although the nitroimidazoles disclosed by the prior art have been. found to be effective against certain bacteria, e.g., SRB, the nitroimidazoles present the disadvantage of being only sparingly soluble in water. Obviously, a bactericide which is to be used in aqeuous liquids is easier to use is less expensive and is more effective if it is easily soluble in the aqeuous liquid.

Accordingly, the object of the present invention is to provide nitroimidazole bactericide compositions which are freely soluble in aqeuous liquids and which are highly effective in inhibiting the growth of SRB.

3. Brief Summary of the Invention It has been found, in accordance with the present invention, that acid and ammomium addition salts of nitroimidazoles and quaternaries thereof are highly effective bactericides in inhibition of SRB and are less expensive and easier to use, in view of their higher water solubility, than are the nitroimidazoles per se. The nitroimidazole salts used in the present invention may be used alone or in conjunction with other anaerobic and aerobic bactericides known to those skilled in the art.

4. Detailed Description of the Invention The bactericides used in the present invention are the salts of 1 -(2-hydroxyethyl)-2-methyl-5- nitroimidazole(metranidazole), 1 ,2-dimethyl-5-nitroimidazole (dimetridazole), 1-(2-hydroxypropyl)-2- methyl-5-nitroimidazole (secnidazole) and 1-methyl-2 isopropyl-5-nitroimidazole(ipronidazole).

The salts of the above-referred to nitroimidazoles include the acid addition salts such as hydrohalides, e.g., hydrochloride, hydrobromide and hydroiodide, phosphates, nitrates, sulfates, acetates, propionates, maleates, fumerates, citrates, tartrates, adipates, methane sulfonates, eth ane disulfonates and the like and also include the ammonium salts and quaternary ammonium compounds.

The nitroimidazole compounds used in the present invention are known compounds and their method of preparation is well known to those skilled in the art. Similarly, the acid addition salts, ammonium salts and quaternary derivatives are likewise easily prepared by those skilled in the art.

The nitroimidazoles salts of the invention are used at concentrations of from about 0.1 ppm to about 25 ppm active ingredient, preferably from about 0.2 ppm to about 1 ppm active ingredi ent.

The following examples illustrate specific, nonlimiting embodiments of the invention, including the best mode of practice of the invention.

In the following examples, the bacteriostatic test for determining inhibition of sulfate reducing bacteria is as follows: 1. Assemble two rows each containing six sulfate API broth vials (9.0 ml each).

2. Transfer 0.1-0.5 ml of test compound solution from an appropriate stock solution to produce the following final concentrations in the sulfate API broth vials: 0, 10, 20, 40, 80 and 160 ppm (shake vials to insure uniform dispersion of test solution).

3. Innoculate each test vial including control with 0.5 ml of a 24-hour culture of "field strain" sulfate-reducing bacteria.

4. Incubate for the indicated number of days at 35 C. Record results after the indicated period of time. Blackening indicates growth of sulfate-reducing bacteria. Bacteriostatic level is the lowest concentration showing no blackening.

Example 1 In this example, the effectiveness of dimetridazole hydrochloride for inhibiting the growth of SRB and anaerobic bacteria is demonstrated and compared against dimtridazole and metranida zole. The results are indicated in Table 1 which presents data generated from a laboratory test showing inhibition of hydrogen sulfide production and bactericidal activity against sulfate reducing bacteria. The test was set up using a modified sulfate API broth as the test medium. The test medium was purged with argon to remove dissolved oxygen and dispensed into 100 ml argon purged serum vials. They were then sterilized. Various concentrations of metranidazole, dimetri dazole and dimetridazole hydrochloride were made from 1% solutions. Each vial was inoculated with 2 ml of a 1-10 dilution of a 24-hour old culture of "field seed" sulfate-reducing bacteria.

After 1, 2 and 7 days of exposures, the levels of surviving SRB and concentrations of hydrogen sulfide were measured.

The data are tabulated in Table 1.

Table 1 Comparison of Inhibitory Activity Against Sulfate Reducing Bacteria a concentration Exposure Time of Active Ingre- 1 Day 2 Days 7 Days Compound dient (ppm) SRB/mlb H2S(ppm) c SRB/ml H2S(ppm) SRB/ml H2S(ppm L Metranidazole 0.4 100 0.5 10-100 0.5 100 20 0.8 0 0.5 0 0.5 100 0.5 1.6 0 0.5 0 0.5 0 0.5 Dimetridazole 0.3 0 0.5 10-100 0.5 100 15 0.6 0 0.5 0 0.5 0 0.5 1.2 0 0.5 0 0.5 0 0.5 Dimetridazole Hydrochloride 0.3 0 0.5 0 0.5 100 20 0.6 0 0.5 0 0.5 0 1.2 0 0.5 0 0.5 0 0.5 Control -- 100,000 4.5 100,000 16 100,000 20 0.5 ppm HZS 100,000 SRB/ml a Test rechallenged with SRB after the 1 and 2 day exposure times.

b SRB enumerated by the extinction dilution technique c H2 S levels measured by the Hach-Alka Seltzer method The data in Table 1 illustrate that dimetridazole hydrochloride is a potent inhibitor of hydrogen sulfide production by SRB. It was also bactericidal, giving complete kill of SRB at 0.6 ppm active ingredient even after repeated rechallenging with bacteria. For comparison, 1.6 ppm active metranidazole was required for complete kill of SRB after seven days exposure.

Example 2 This example presents the results of a field kill test done at a commercial water plant. The produced water at the plant was a moderate brine and contained about 40 ppm hydrogen sulfide. The produced water was dispensed into 50 ml argon purged serum vials. Various concentrations of dimetridazole and dimetridazole hydrochloride were made. After 24-hour exposure, levels of SRB, anaerobic bacteria and total bacteria by ATP were measured. The results are tabulated in Table 2.

Table 2 a Comparison of Bactericidal Activity Active In- Surviving Bacteria/ml gredient Sulfate ATP Total Compound (ppm) Reducers Anaerobic Method Bacteria Dimetridazole 3 10-100 100 16,000,000 0 6 10-100 100 8,700,000 0 12 10-100 100 9,800,000 0 24 10-100 10-100 14,000,000 0 Dimetridazole Hydrochloride 3 10-100 100 6,900,000 0 6 10-100 100 6,500,000 0 12 10-100 100 11,000,000 0 24 1-10 10-100 7,300,000 0 Control -- 100 100 6,400,000 0 a Test Solution: Produced water from commercial water plant clear tank Exposure Time: 24 Hrs.

The results illustrated in Table 2 show that levels of up to 24 ppm active dimetridazole had no effect on bacteria present in the produced water. The dimetridazole hydrochloride reduced SRB levels by 90 percent at 24 ppm active concentration.

It is contemplated that the salts of metranidazole, ipronidazole and secnidazole would be similarly effective and that, in addition to the hydrochloride salt as illustrated in the above examples, the hydrobromide, hydroiodide and the phosphates, nitrates, sulfates, acetates, propionates, maleates, fumerates, citrates, adipates, tartrates, methane sulfonates, ethane disulfonates and ammonium salts would be similarly effective. Further, it is contemplated that the quaternary ammonium compounds may also be used with similar results.

The nitroimidazole salts may be used in conjunction with other bactericides including aldehydes, compounds which liberate aldehydes, phenols, e.g., p-chloro-m-cresol and phenol, heavy metals, isothiazolones, mixtures of halogenated and non-halogenated isothiazolones and mixtures thereof. Bactericidal compositions containing the nitroimidazole salts of the present invention may be used in oil field and industrial hydrocarbon liquids, and in mixtures, dispersions or emulsions of hydrocarbon and aqeuous liquids, for example, downhole injection waters such as water floods, polymer floods and fracturing fluids, oil-in-water and water-in-oil emulsions, gas transmission lines and storage fields, in hydrostatic testing of equipment such as tanks, vessels and pipe lines, in cutting and metal working fluids, in petroleum storage tanks and industrial process waters, in paper pulp sulfite processing fluids, in electroplating solutions and in pipes, filters and other equipment used to produce, transport and store oil field and industrial process water liquids.

While the illustrative embodiments of the invention have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the spirit and scope of the invention.

Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and description set forth herein, but rather that the claims be construed as encompassing all the features of patentable novelty which reside in the present invention, including all features which would be treated as equivalents thereof by those skilled in the art to which the invention pertains.

Claims (25)

1. A bactericidal composition containing a nitroimidazole salt.

2. Composition of claim 1 wherein the salt is the hydrohalide salt.

3. Composition of claim 1 wherein the salt is a phosphate salt.

4. Composition of claim 1 wherein the salt is a nitrate salt.

5. Composition of claim 1 wherein the salt is a sulfate salt.

6. Composition of claim 1 wherein the salt is an organic acid salt.

7. Composition of claim 1 wherein the salt is a methane sulfonate salt.

8. Composition of claim 1 wherein the salt is an ethane disulfonate salt.

9. Composition of claim 1 wherein the salt is a quaternary ammonium salt.

10. Composition of claim 1 which contains a corrosion inhibitor.

11. Composition of claim 1 which contains an aldehyde.

12. Composition of claim 1 which contains a mixture of isothiazolones.

13. Composition of claim 1 which further contains a phenol.

14. Composition of claim 1 which further contains a heavy metal compound.

15. Method of inhibiting the growth of sulfate-reducing bacteria in oil field and industrial liquids which comprises adding thereto an effective SRB inhibiting amount of a nitroimidazole salt in aqeuous solution.

16. Method of inhibiting the growth of sulfate-reducing bacteria in an oil field water flood which comprises adding thereto an effective SRB inhibiting amount of a nitroimidazole salt.

17. Method of inhibiting the growth of sulfate-reducing bacteria in an oil field polymer flood which comprises adding thereto an effective SRB inhibiting amount of a nitroimidazole salt.

18. Method of inhibiting the growth of sulfate-reducing bacteria in an oil field fracturing fluid which comprises adding thereto an effective SRB inhibiting amount of a nitroimidazole salt.

19. Method of inhibiting the growth of sulfate-reducing bacteria in an emulsion of oil and water which comprises adding thereto an effective SRB inhibiting amount of a nitroimidazole salt.

20. Method of inhibiting the growth of sulfate-reducing bacteria in industrial process waters which comprises adding thereto an effective SRB inhibiting amount of a nitroimidazole salt.

21. Method of inhibiting the growth of sulfate-reducing bacteria in production oil field and gas well treatments which comprises adding thereto an effective SRB inhibiting amount of a nitroimidazole salt.

22. Method of inhibiting the growth of sulfate-reducing bacteria in gas transmission lines and storage field which comprises adding thereto an effective SRB inhibiting amount of a nitroimidazole salt.

23. Method of inhibiting the growth of sulphate-reducing bacteria during hydrostatic testing of equipment which comprises adding thereto an effective SRB inhibiting amount of a nitroimidazole salt.

24. Method of inhibiting the growth of sulfate-reducing bacteria in metal cutting and metal working liquids which comprises adding thereto an effective SRB inhibiting amount of a nitroimidazole salt.

25. Method of inhibiting the growth of sulfate-reducing bacteria in petroleum storage tank water bottoms which comprises adding thereto an effective SRB inhibiting amount of a nitroimidazole salt.