JP2009136814A - Preparation method of weak acidic electrolytic water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preparing weak acidic electrolytic water with a predetermined pH even when low hardness water is used without requiring labor for adjusting an electrolytic condition and lowering the occurrence efficiency of elemental chlorine by solving the problem that pH is lowered according to circumstances if raw water extremely low in hardness is used in a method for preparing weak acidic electrolytic water by electrolyzing dilute hydrochloric acid in a non-diaphragm electrolytic cell and the adjustment of the electrolytic condition or the adjustment for lowering the concentration of the raw material hydrochloric acid is required. <P>SOLUTION: By substituting a part of hydrogen ions with sodium ions by dissolving sodium bicarbonate in the diluting water of hydrochloric acid, even when water low in hardness is used, weak acidic electrolytic water with proper pH can be prepared without requiring the fine adjustment of the electrolytic condition or operation for lowering electrolytic efficiency such as the concentration lowering operation of hydrochloric acid or the like. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a technique for preparing slightly acidic electrolyzed water by electrolyzing dilute hydrochloric acid and diluting it with water. More specifically, the present invention relates to a technique for preparing dilute hydrochloric acid as a raw material for electrolyzing to prepare slightly acidic electrolyzed water.

In recent years, the field of hygiene and medical care is caused by pathogens and drug-resistant microorganisms that are unfamiliar to ears, due to intensifying human movement, globalization of the distribution of food and food materials, and social changes such as medical care that relies on antibiotics. Facing outbreaks and incurable diseases. The people who are in contact with these news every day are worried and the interest in hygiene measures is growing. Along with this, the market for bactericides as a countermeasure and products with bactericidal functions continues to expand. Under such circumstances, so-called bactericidal electrolyzed water produced by electrolysis of chloride ions, which appeared as a new face of bactericides 10 years ago, has been supported by the establishment of the Ministry of Health, Labor and Welfare standards, Is becoming established.

Slightly acidic electrolyzed water (name of food additive “slightly acidic hypochlorous acid water”) in the sterilized electrolyzed water is generated by electrolyzing dilute hydrochloric acid in a non-diaphragm electrolyzer (Patent Document 1). Therefore, it contains almost no salt and has no effect on the surroundings, so it can be used for spraying in addition to the usual use for sterilization and washing, and has started to be widely used for environmental sterilization, deodorization, safe humidification, etc. . The present invention was carried out for the purpose of further enhancing convenience in the production of the slightly acidic electrolyzed water and spurring its popularization.
Japanese Patent No. 3798486

As described above, slightly acidic electrolyzed water having many excellent properties is gradually spreading, but in order to further promote the spread, it is required to improve convenience in its production method.

The slightly acidic electrolyzed water is prepared by electrolyzing dilute hydrochloric acid in a non-diaphragm electrolyzer and diluting the produced electrolyte with water. Chlorine ions contained in dilute hydrochloric acid are electrode oxidized as shown in chemical formula 1 to form single chlorine, and the chlorine reacts with water to generate hypochlorous acid (HOCl) as shown in chemical formula 2.

(Chemical formula 1) 2HCl → H ₂
+ Cl ₂

(Chemical formula ₂ ) Cl ₂
+ H ₂ O → HOCl + HCl

This hypochlorous acid is a bactericidal component. However, as can be seen from the chemical formula 2, hydrochloric acid is generated simultaneously with hypochlorous acid. Part of the hydrochloric acid generated in this way may be discharged from the electrolytic cell as it is. After leaving the electrolytic cell, it is diluted with water, but since the dilution ratio is extremely high, 1000 times or more, it is usually neutralized by the effect of dilution and the hardness component contained in the diluted water, and the generated water is as the name suggests. It indicates the pH of the slightly acidic region.

However, when the hardness of the dilution water is extremely low, the neutralization effect by the hardness component is low, so it may be lower than the predetermined pH. As a countermeasure, the electrolysis conditions are adjusted and the amount of hydrochloric acid discharged from the electrolytic cell is reduced. It was necessary to let them. As another countermeasure, there is a method of reducing the original concentration of dilute hydrochloric acid. However, if the concentration of the hydrochloric acid as the raw material is lowered, the chlorine ion concentration is naturally lowered, and the generation efficiency of simple chlorine during electrolysis is also lowered. Therefore, the present inventor, in a method for producing slightly acidic electrolyzed water by electrolyzing dilute hydrochloric acid in a diaphragmless electrolytic cell, does not require time and effort to adjust electrolysis conditions, does not reduce the generation efficiency of simple chlorine, and has low hardness. An object of the present invention is to provide a method for preparing slightly acidic electrolyzed water having a predetermined pH even when water is used.

In order to promote the spread of slightly acidic electrolysis having many excellent properties, it is necessary to improve convenience in its production method. For this reason, the present inventor did not adjust the electrolysis conditions and used simple chlorine. The research on means for providing a method for preparing slightly acidic electrolyzed water having a predetermined pH even when low-hardness water is used has been advanced.

First, attention was paid to the fact that the balance equation of the substance through the entire electrolytic reaction shown in the chemical formula 3 can be obtained by adding and organizing the chemical formula 1 and the chemical formula 2 together.

(Chemical 3) 2H ^{+
_{+ 2Cl - + H 2 O →}} H 2 + HOCl
This chemical formula 3 shows that the pH is increased by hydrogen ions generated by dissociation of the first hydrochloric acid as hydrogen gas and out of the system. Therefore, as another method for reducing the remaining amount of hydrochloric acid in the electrolytic solution, it was considered that the hydrogen ion concentration before electrolysis should be lowered. Furthermore, as a method for reducing the chlorine ion concentration of the stock solution and not lowering the electrical conductivity of the stock solution, the inventors conceived that some of the hydrogen ions may be replaced with other cations.

Then, the present inventor dissolved sodium bicarbonate in water for diluting hydrochloric acid, whereby a part of hydrogen ions was replaced by sodium ions by the reaction shown in the chemical formula 4, and other chemical components Was the same as when only hydrochloric acid was diluted with water, and this was made the first mode for solving the problem.

(Chemical Formula 4) NaHCO ₃
^{+ Cl - + H + → Na} + + Cl -
+ H ₂ O + CO ₂ ↑

Next, the amount of sodium bicarbonate added may need to be increased or decreased depending on the hardness of the raw water, but as a result of a survey of the hardness of tap water in Japan, it is considered to have the lowest hardness for public water supply. Was around 10 ppm. Accordingly, when the hydrochloric acid concentration of dilute hydrochloric acid is 20% or less, it is confirmed that the sodium bicarbonate concentration of hydrochloric acid-diluted water capable of preparing a slightly acidic electrolyzed water having a predetermined pH with water having a hardness of 10 ppm is 700 ppm. It has also been confirmed that the sodium bicarbonate concentration of hydrochloric acid-diluted water in which slightly acidic electrolyzed water having a predetermined pH can be prepared with water having a hardness of 40 ppm is 300 ppm. The second mode for solving the problem is to set 1 ppm to 700 ppm, more preferably 300 ppm to 700 ppm.

Furthermore, the dilute hydrochloric acid prepared by diluting in advance with the sodium bicarbonate solution as described above can be used as it is for the preparation of slightly acidic electrolyzed water using soft water as a raw material, and the sodium bicarbonate concentration is 0.1 ppm or more and 700 ppm or less. The present invention was completed by using diluted hydrochloric acid diluted with a sodium bicarbonate solution of preferably 300 ppm or more and 700 ppm or less as a third embodiment for solving the problems.

By dissolving sodium bicarbonate in water for diluting hydrochloric acid according to the present invention, even when preparing slightly acidic electrolyzed water using raw water with extremely low hardness, adjustment of electrolysis conditions and dilute hydrochloric acid concentration are reduced. It is now possible to prepare slightly acidic electrolyzed water having a predetermined pH without taking measures such as the above.

Alternatively, according to the present invention, the concentration of sodium bicarbonate in diluted water is 0.1 ppm or more and 700 ppm or less, more preferably 300 ppm or more and 700 ppm or less. Acidic electrolyzed water can be generated. Further, by providing dilute hydrochloric acid diluted with a sodium bicarbonate solution having a sodium bicarbonate concentration of 0.1 ppm or more and 700 ppm or less, more preferably 300 ppm or more and 700 ppm or less, a slight acidic electrolysis with an appropriate pH can be easily performed even in soft water. It became possible to purify the water.

Next, in order to ensure an understanding of the present invention, an example of the best mode for carrying out the present invention will be described based on the examples. However, the description of the examples is limited to each example, and is not directly related to the claims of this patent.

35% strength food additive hydrochloric acid was diluted with 700 ppm sodium bicarbonate solution to prepare 9% dilute hydrochloric acid. Using this dilute hydrochloric acid, slightly acidic electrolyzed water was produced using a self-made electrolyzer whose flow diagram is shown in FIG. The electrolytic cell (2) was a 10 × 20 cm plate electrode and a 3 cell bipolar type. The raw water with a calcium hardness of 10 ppm was adjusted to a constant flow rate of 300 L / h by a constant flow valve (3), the electrolysis voltage was a constant voltage of 2.5 V, and the electrolysis current was a target of 30 A. The dilute hydrochloric acid was generated by supplying the dilute hydrochloric acid supply pump (1) to the electrolytic cell when the current value cuts off 30A, and stopping the supply when the current value exceeded 30A. As a result, slightly acidic electrolyzed water having an effective chlorine concentration of 18 ppm and a pH of 5.6 was produced at 300 L / h.

Another example of another best mode for carrying out the present invention will be described in another example. 35% strength food additive hydrochloric acid was diluted with 300 ppm sodium bicarbonate solution to prepare 9% dilute hydrochloric acid. Using this dilute hydrochloric acid, slightly acidic electrolyzed water was produced using the same apparatus as in Example 1. The raw water flow rate with a calcium hardness of 40 ppm was 300 L / h, and the electrolysis voltage was 2.5 V and the electrolysis current was 30 A. As a result, slightly acidic electrolyzed water having an effective chlorine concentration of 20 ppm and a pH of 5.8 was produced at 300 L / h.

Further, another example of another best mode for carrying out the present invention will be described. 35% strength food additive hydrochloric acid was diluted with 700 ppm sodium bicarbonate solution to prepare 9% dilute hydrochloric acid. Using this dilute hydrochloric acid, slightly acidic electrolyzed water was produced using the same apparatus as in Example 1. The raw water flow rate with a calcium hardness of 110 ppm was 300 L / h, and the electrolysis voltage was 2.2 V and the electrolysis current was 30 A. As a result, slightly acidic electrolyzed water having an effective chlorine concentration of 20 ppm and a pH of 6.0 was produced at 300 L / h.

Flowchart of slightly acidic electrolyzed water generating apparatus for explaining examples

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dilute hydrochloric acid supply pump 2 Electrolyzer 3 Constant flow valve 4 DC constant voltage power supply 5 Control apparatus 6 Dilute hydrochloric acid tank

Claims (3)

In a method for producing slightly acidic electrolyzed water by electrolyzing dilute hydrochloric acid in a diaphragmless electrolytic cell and diluting with water, dilute hydrochloric acid to be used is prepared by diluting hydrochloric acid with sodium bicarbonate solution. Generation method of slightly acidic electrolyzed water 2. The slightly acidic electrolyzed water according to claim 1, wherein the concentration of sodium bicarbonate in the sodium bicarbonate solution used for diluting hydrochloric acid is 0.1 ppm or more and 700 ppm or less, more preferably 300 ppm or more and 700 ppm or less. Law Dilute hydrochloric acid diluted with a sodium bicarbonate solution, more preferably 0.1 ppm to 700 ppm, and even more preferably 300 ppm to 700 ppm sodium bicarbonate solution

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