JP2001300547A - Production method of sterilized water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for easily obtaining sterilized water whose pH and effective chlorine concentration are specific. SOLUTION: Water is continuously fed to a mixing tank and water temperature in the mixing tank is maintained at <=70 deg.C, and hypochlorite (A) or a pH regulating agent (B) are added, while changing the addition quantity in accordance with a quantity of water fed to the mixing tank or the effective chlorine concentration of water in the mixing tank or the pH, etc., thus the sterilized water with 3-8 pH, 5-5,000 ppm effective chlorine concentration is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing sterilized water containing hypochlorous acid.

[0002]

2. Description of the Related Art Raw water contains a hypochlorite such as sodium hypochlorite (NaClO) and an acid such as hydrochloric acid (HCl).
By adding and mixing the above, sterilized water in which hypochlorite (HClO) having strong sterilizing power is generated in water can be generated. However, when sodium hypochlorite reacts with hydrochloric acid, toxic chlorine gas is generated and it is dangerous.
In order to solve this problem, Japanese Patent Application Laid-Open No. H11-188083 discloses that the amount of the aqueous sodium hypochlorite solution and / or the aqueous acid solution added to the flow rate of the raw water in the water supply pipe is maintained so as to maintain a specific pH and a residual chlorine concentration. There is proposed a method of adjusting and mixing.

[0003]

However, in the above method, the amount of addition of sodium hypochlorite and the acid is determined depending on the flow rate of the raw water, so that it may not be possible to sufficiently cope with abnormal operation. is there. For example, chlorine gas may be generated when the addition balance between hypochlorite and acid is disrupted due to a valve failure or the like. The above method is not sufficient to stably produce sterilized water having a certain effective chlorine concentration and pH.

An object of the present invention is to provide a method for producing sterilized water which is simple and has a stable quality.

[0005]

SUMMARY OF THE INVENTION According to the present invention, water is continuously supplied to a mixing tank, and while the temperature of the water in the mixing tank is maintained at 70 ° C. or lower, (i) water supplied to the mixing tank is supplied. Adding hypochlorite (A) in accordance with at least one of the amount of water and the available chlorine concentration of water in the mixing tank; and (ii) the amount of (A) added and the pH of water in the mixing tank. The present invention relates to a method for producing sterilized water having a pH of 3 to 8 and an effective chlorine concentration of 5 to 5,000 ppm by both adding a pH adjuster (B) according to at least one of the values.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the present invention will be described with reference to FIG. In FIG. 1, 1 is a mixing tank, 2 is a supply tank for hypochlorite, and usually contains an aqueous solution containing hypochlorite. Reference numeral 3 denotes a supply tank for the pH adjusting agent, which usually contains an aqueous solution containing the pH adjusting agent. Reference numeral 4 denotes a water supply pipe, which is a flow meter 5 as a means for detecting a flow rate.
It has. Water is supplied from the water supply pipe 4 to the mixing tank 1, and the water temperature is adjusted to 70 ° C. or lower, preferably 20
While maintaining the temperature at ~ 60 ° C, the aqueous solution of hypochlorite and pH
A regulator aqueous solution is added via pumps P1 and P2.
When the water temperature exceeds 70 ° C., the decomposition of hypochlorite is promoted, the effective chlorine concentration decreases, and it becomes difficult to stably produce sterilized water.

In the present invention, (i) adding hypochlorite (A) according to at least one of the amount of water supplied to the mixing tank and the available chlorine concentration of water in the mixing tank; (Ii) Sterilization at a predetermined pH and effective chlorine concentration by both adding the pH adjuster (B) in accordance with at least one of the addition amount of (A) and the pH value of water in the mixing tank. Water can be produced. In (i), the amount of water supplied to the mixing tank can be detected by the flow meter 5, and the effective chlorine concentration of the water in the mixing tank can be measured by an effective chlorine concentration automatic measuring device. In (ii), the addition amount of (A) can be detected by the supply amount of the aqueous solution from the pump P1, and the pH value of the water in the mixing tank can be measured by a pH meter. Preferably, such information is transmitted as electrical signals to means for controlling the amount of addition of (A) and (B). Thereby, the method of the present invention can be automated. Of course, individual measurements may be made as needed to control the amounts of (A) and (B) added.

The hypochlorite (A) used in the present invention is preferably an alkali metal salt such as sodium hypochlorite and potassium hypochlorite, and particularly preferably sodium hypochlorite.

The pH adjuster (B) used in the present invention includes an alkali metal hydroxide, an alkaline earth metal hydroxide, an inorganic acid or a salt thereof, an organic acid or a salt thereof, and the like. Examples of alkali metal hydroxides and alkaline earth metal hydroxides include sodium hydroxide, potassium hydroxide, calcium hydroxide and the like. As inorganic acids or salts thereof, hydrochloric acid, sodium sulfate, sodium nitrate,
Sodium chloride, sodium carbonate, potassium bicarbonate,
Sodium hydrogen carbonate, potassium hydrogen carbonate, magnesium sulfate, magnesium nitrate, magnesium chloride, magnesium carbonate, trisodium phosphate, tripotassium phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, sodium dihydrogen phosphate, phosphoric acid Potassium dihydrogen, sodium polyphosphate and the like can be mentioned. Examples of the organic acid or a salt thereof include malonic acid, succinic acid, glutaric acid, adipic acid, a saturated dibasic acid such as sebacic acid or a salt thereof, and fumaric acid or an unsaturated dibasic acid such as maleic acid or a salt thereof. No. Preferably, it is a saturated dibasic acid or a salt thereof, more preferably a saturated dibasic acid having 3 to 10 carbon atoms or a salt thereof, and particularly preferably succinic acid or a salt thereof.

In the present invention, it is preferable to add (B) after the addition of (A) in order to prevent a rapid rise in water temperature and generation of chlorine gas.

In the present invention, a surfactant can be added so that the water in the mixing tank contains the surfactant.
The surfactant can be selected from anionic surfactants, cationic surfactants, nonionic surfactants and amphoteric surfactants, and those which are stable in an aqueous solution of hypochlorous acid are used. Among them, cationic surfactants such as primary amine salt, secondary amine salt, tertiary amine salt, and quaternary ammonium salt; amino acid amphoteric surfactant, betaine amphoteric surfactant, imidazoline amphoteric Surfactants and amphoteric surfactants such as amine oxides are preferred.
A quaternary ammonium salt and an amine oxide are preferred, and an amine oxide is particularly preferred. As the amine oxide, alkyldimethylamine oxide is preferable,
Particularly, those having an alkyl group having 8 to 18 carbon atoms are preferable. The surfactant may be added to the water in the water supply pipe 4, added to the tank 1, 2 or 3, or added to the mixing tank 1 by providing a separate surfactant supply tank. But it is good. In particular, it is preferable to add it to the tank 1 or 3. The amount to be added is appropriately determined in consideration of the use of the sterilizing water and the like so that the final concentration becomes appropriate.

Although FIG. 2 shows a flowchart showing an example of the method for producing sterilized water according to the present invention, the processing and the judgment can be further changed. In FIG. 2, the addition of a surfactant is optional.

[0013]

According to the present invention, high-performance sterilized water having stable pH and effective chlorine concentration can be easily produced. Further, the method of the present invention can be incorporated as a part of a manufacturing process of various industrial products.

[0014]

EXAMPLE Sterilized water was produced using the apparatus shown in FIG. First, 196 L of tap water was supplied from the water supply pipe 4 to the mixing tank 1 (capacity: 300 L) with the drain port closed, and the water temperature was adjusted to 30 ° C. by the temperature control means 6. To this, 2 L of an aqueous solution of sodium hypochlorite (concentration: 1% by weight) was supplied from the supply tank 2.
Then, 2 L of a pH adjuster aqueous solution (succinic acid concentration of 1% by weight) was supplied from the supply tank 3 to obtain sterilized water having a pH of 6.3 and an effective chlorine concentration of 100 ppm. Next, the drain port of the mixing tank 1 was opened to start discharging the sterilizing water, and the supply of tap water to the mixing tank 1 was started. At this time, the pH of the water in the mixing tank 1 was measured with a pH meter (manufactured by Toa Denpa Kogyo Co., Ltd., model number: HM-30G), and the effective chlorine concentration was measured with an effective chlorine concentration automatic measuring device. In this example,
The effective chlorine concentration is fed back to the control means of the pump P1, and the pH data is fed back to the control means of P2. Further, the flow rate data of the tap water measured by the flow meter 5 installed in the water supply pipe 4 is fed back to the control means of the pump P1. Further, the supply amount data of the aqueous solution of sodium hypochlorite from the pump P1 is fed back to the control means of the pump P2. The amounts of the aqueous sodium hypochlorite solution and the aqueous solution of the pH adjuster are controlled in relation to each other, and the pH and the effective chlorine concentration of the sterilizing water from the outlet are maintained at the above-mentioned values.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an apparatus for performing the method of the present invention.

FIG. 2 is a flowchart illustrating an example of the method of the present invention.

[Explanation of symbols]

 1: Mixing tank 2: Hypochlorite supply tank 3: pH adjuster supply tank 4: Water supply pipe 5: Flow meter 6: Temperature control means

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Noboru Matsuo 1334 Minato 1334 Minato, Wakayama, Wakayama Pref. Person Shigeru Tamura 1334 Minato, Wakayama City, Wakayama Prefecture F-term in Kao Corporation Research Institute 4D050 AA01 AB06 BB06 BD04 BD08 CA13

Claims (4)

[Claims] 1. While continuously supplying water to a mixing tank and maintaining the temperature of the water in the mixing tank at 70 ° C. or lower, (i) the amount of water supplied to the mixing tank and the water in the mixing tank. Adding hypochlorite (A) in accordance with at least one of the available chlorine concentrations of (a), and (ii) the amount of (A) added and the amount of water in the mixing tank.
A method for producing sterilized water having a pH of 3 to 8 and an effective chlorine concentration of 5 to 5,000 ppm by both adding a pH adjuster (B) according to at least one of the H values. 2. The method according to claim 1, wherein the addition of (B) is performed after the addition of (A). 3. The method according to claim 1, wherein the surfactant is added so that the water in the mixing tank contains the surfactant. 4. The method according to claim 3, wherein the surfactant is at least one selected from quaternary ammonium salts and amine oxides.