JPH045517B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to a slime control method. More specifically, the present invention relates to a method of treating slime produced by microorganisms in an aqueous system using hydrazine and 2-mercaptopyridine-N-oxide zinc salt. In recent years, it has been known that slime-related problems in various industrial waters have frequently occurred due to microbial contamination, causing various adverse effects. For example, slime forms in heat exchangers and waste water cooling pipes for circulation cooling systems used in petrochemical plants and chemical plants, clogging the pipes and reducing cooling efficiency, or in paper mills. Microorganisms generated in white water form a muddy slime that peels off and mixes with the paper, causing various problems such as the paper being cut during the winding process, spots on the paper, and unpleasant odors. be. As industrial disinfectants, agents that have strong sterilizing power but are toxic to human stock or cause environmental pollution by mixing with wastewater are avoided. Hydrazine is known as a drug for preventing slime damage caused by microorganisms that grow and multiply in these various water systems. Hydrazine generally has the advantage of being weakly toxic and decomposing into non-toxic water and nitrogen gas, but on the other hand, it is easily decomposed in non-toxic water that is constantly in contact with air, so a large amount of hydrazine is used. must be used, which makes the cost too high to be practical. The inventors of this invention conducted intensive research with the aim of developing a slime control method that takes advantage of the characteristics of hydrazine and has even lower toxicity. The inventors have completed this invention by discovering that a significant synergistic effect can be achieved by reducing the amount of hydrazine added to about 1/20 to 1/200 compared to when hydrazine is used alone. 2-Mercaptopyridine-N-oxide zinc salt, which is one of the active ingredients of this invention, is a well-known compound under the trade name "zinc pyrithione" and is incorporated into dandruff shampoos, rinses, and the like. In general, metal derivatives (metal salts) of 2-mercaptopyridine-N-oxide are known to have antibacterial and antifungal activities, but as slime control agents added to aqueous systems, water-insoluble 2-mercaptopyridine-N-oxide is generally used as a slime control agent.
-Mercaptopyridine-N-oxide The water-soluble alkali metal salt was easier to handle than the zinc salt and had better effects. (Japanese Patent Application Laid-open No. 52-83934) Furthermore, the use of hydrazine and other drugs in combination is disclosed in, for example, JP-A-57-212107 and JP-A-58-83934.
It is known as Publication No. 67610. However, it is surprising that the effects of the combination of the present invention are significantly better than the effects of the combination of these and the combination of hydrazine and known slime control agents. The hydrazine used in this invention may be in the form of hydrazine as it is, but since it is inconvenient to handle, inorganic acids of hydrazine such as hydrazine hydrate, hydrazine hydrochloride, hydrazine sulfate, hydrazine nitrate, hydrazine carbonate, hydrazine phosphate, and hydrazine sulfamate. Salts of organic acids of hydrazine such as hydrazine acetate, hydrazine citrate and hydrazine adipic acid, and hydrazine derivatives such as phenylhydrazine, hydroxyhydrazine and monomethylhydrazine are used. In this invention, the appropriate blending ratio that produces a synergistic effect compared to when the two active ingredients are used alone is hydrazine (N ₂ H ₄ equivalent).
and 2-mercaptopyridine-N-oxide zinc salt in an amount of 5:95 to 95:5 parts by weight, preferably 10:
90-85:15 parts by weight. Furthermore, the amount of addition according to the method of this invention is such that synergistic sterilization occurs even when both active ingredients are used in the process water of paper manufacturing process or industrial cooling water at the most preferable ratio when the concentration in the system is usually less than 1 ppm. The strength and bacteriostatic power are insufficient for practical purposes, and adding more than 100 ppm has no particular advantage in terms of effectiveness compared to adding less than 100 ppm.
It's not economical. According to this invention, 1 to 100 ppm,
Preferably, by adding 5 to 30 ppm, the number of harmful microorganisms can be reduced to 10 ³ pieces/ml or less. When adding hydrazine and 2-mercaptopyridine-N-oxide zinc salt to an aqueous system in the method of the present invention, both drugs may be mixed in advance and added, or each drug may be added separately. .
Furthermore, the mode of addition may be continuous administration or intermittent administration. Note that when both drugs are mixed in advance, 2-mercaptopyridine-N-oxide zinc salt is not soluble in water by itself, so an appropriate dispersant (sodium silicate, sodium silicate,
It is usually preferred to formulate with hydrazine, followed by dispersion with hydrazine (such as sodium phosphate). Therefore, the present invention also provides a slime control agent containing hydrazine and 2-mercaptopyridine-N-oxide zinc salt as active ingredients. Water systems to which the slime control method of the present invention can be applied include, for example, acidic/neutral white water systems for papermaking in acidic/neutral conditions, PH7.5-10
The alkaline paper-making white water system can be mentioned, and particularly the alkaline paper-making white water system shows excellent effects. Thus, by using hydrazine and 2-mercaptopyridine-N-oxide zinc salt in combination, this invention can economically and efficiently control the adhesion and generation of aqueous slime, and has extremely high industrial value. It's a method. Next, a synergistic effect test example and examples of two components used to complete this invention will be explained. Test Examples Test Example 1 (Bactericidal effect on standard fungus Pseudomonas Aerginosa 7144) Pseudomonas Aerginosa 7144 was planted in a bouillon medium and cultured at 37°C for 15 hours. After that, it was planted in a new bouillon medium, and when the absorbance reached 0.6, the culture solution was diluted with sterile water to 100%
The mixture was diluted twice, NaSO ₃ was added to the solution to a concentration of 100 ppm, and 10 ml was dispensed into an L-shaped test tube. A predetermined drug was added to each sample and the samples were left in contact with each other for 4 hours using a shaker. Thereafter, they were planted in a bouillon medium and cultured in a flan vessel at 37°C for 48 hours, and the number of viable bacteria per ml was measured after culturing. The results are shown in Table 1.

[Table] In the table, * marks indicate those in this invention.
Test Example 2 (Hydrazine and 2-mercaptopyridine-N-
Synergistic effect at each ratio of zinc oxide salt) Hydrazine hydrate ( _N2H4.H2O ) and 2 _{- mercaptopyridine} -N
- Various ratios of zinc oxide salts were tested for their bactericidal efficacy. (Number of viable bacteria: 7.0×10 ⁶ cells/ml) The results are shown in Table 2.

[Table] (Considerations) 2-Mercaptopyridine-N-oxide zinc salt alone requires 40 ppm to reduce the number of viable bacteria to 10 ³ (cells/ml), while hydrazine alone requires
640ppm is required. In comparison, the hydrazine of this invention is 3.2 ppm (1/200 of the amount when used alone)
and 2-mercaptopyridine-N-oxide 10ppm
(1/4 the amount when used alone),
The number of viable bacteria can be reduced to 10 ³ (cells/ml) or less. (See Test No. 8) Similarly, in Test No. 11, hydrazine was used in combination with 1/100 of the amount used alone and 1/5.3 of 2-mercaptopyridine-N-oxide zinc salt, and in Test No. 19. It is understood that by using 1/21.3 and 1/16 of the amount used alone, the number of viable bacteria was reduced to less than 10 ³ (cells/ml), demonstrating a remarkable synergistic effect. Ru. The vertical axis is the total amount of drugs added (ppm) that reduces the number of viable bacteria to 10 ³ (counts/ml) or less, and the ratio of N ₂ H ₄ amount to the total amount added (%)
Figure 1 shows a plot of the test results with the horizontal axis being . (The numbers in the figure indicate the test numbers in Table 2.) This figure shows that a remarkable synergistic effect is exerted by using hydrazine and 2-mercaptopyridine-N-oxide zinc salt together in various ratios. is understood. A preferred ratio of both is hydrazine:2-mercaptopyridine-N
- It is found that the ratio of the zinc oxide salt is 5:95 to 95:5, more preferably 10:90 to 85:15. Example 1 (including comparative examples) (Effect of combined use of hydrazine and known disinfectants on on-site white water) No. 4 m/c Save All white water for alkaline papermaking machine at a certain paper mill (PH7.4, viable bacteria count 2.0) ×10 ⁶
10 ml of the sample was collected and dispensed into L-shaped test tubes. The prescribed drug was added to each sample, and the samples were left in contact with each other for 5 hours in a shaker, then planted in a bouillon medium and placed in a flan vessel at 37°C for 48 hours. The cells were cultured for a period of time, and the number of viable bacteria per ml of culture solution was measured. The results are shown in Table 3.

【table】

[Table] Examples 2 to 5 According to the procedure of Example 1, hydrazine hydrate and 2
- The bactericidal effect of mercaptopyridine-N-oxide with zinc salt was measured. The results are shown in Table 4 along with the water quality and bacterial quality of the white water.

【table】

[Table] Example 6 According to the procedure of Example 1, the bactericidal effect of hydrazine hydrate and 2-mercaptopyridine-N-oxide zinc salt was measured on cooling water collected from a certain petrochemical factory. The results are shown in Table 5 along with the quality of the cooling water. (However, in this case, the contact time in the shaker was 4 hours.)

[Table] As described above, the effect of the combination of hydrazine and 2-mercaptopyridine-N-oxide zinc salt in this invention is that slime control is extremely difficult in general cooling water systems, acidic/neutral papermaking white water systems, and in general. It also shows a good synergistic effect in the alkaline paper-making white water system, and the generation of slime, which has traditionally been a problem for various industrial water, has been drastically reduced, making it possible to operate without any problems. It was a demonstration of its value. Especially when compared with the effects of other known slime control methods, the effects of the present invention are even more excellent in alkaline papermaking white water systems.

[Brief explanation of drawings]

FIG. 1 shows a plot of the test results of Test Example 2.

Claims (1)

[Claims] 1. Hydrazine and 2-mercaptopyridine-N-
A slime control method characterized by adding zinc oxide salt to a water system to control slime. 2 Hydrazine and 2-mercaptopyridine-N-
2. The method for controlling slime according to claim 1, wherein the ratio of addition to the zinc oxide salt is 5:95 to 95:5 parts by weight. 3 Hydrazine and 2-mercaptopyridine-N-
3. The method for controlling slime according to claim 2, wherein the ratio of addition to zinc oxide salt is 10:90 to 85:15 parts by weight. 4 Hydrazine and 2-mercaptopyridine-N-
Zinc oxide salt and the total concentration of both in the aqueous system is 1.
The slime control method according to any one of claims 1 to 3, which comprises adding ~100 ppm.