JP2892121B2 - Method for producing sterile water containing hypochlorous acid by electrolysis - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for producing sterilized water containing hypochlorous acid by electrolysis.

[Background of the Invention] An aqueous solution of hypochlorous acid has a pH of 8 or more and hypochlorite ion (C
O ⁻ ), and the bactericidal activity is significantly reduced in comparison with the case of hypochlorous acid (HClO). However, it is known that in the range of pH 3 to 7, it is kept in the form of HClO and the bactericidal activity is drastically increased (see FIG. 2). However, even at a low concentration of about 30 to 60 ppm, a sterilizing effect equivalent to sterilizing water with a residual chlorine concentration of about 200 at pH 8 can be obtained.

As a method for obtaining such sterilizing water, sodium hypochlorite (NaClO) and hydrochloric acid HCl have been conventionally added to raw water such as tap water.
Is used for sterilization of pools and the like.

[Problems to be solved by the invention]

However, if sodium hypochlorite and hydrochloric acid are mixed with raw water to obtain sterilizing water having the above properties, relatively large amounts of sodium hypochlorite are required to adjust the pH value of sterilizing water to 5 to 6. , The cost is high.

In addition, the conventional method of simply mixing hydrochloric acid (HCl aqueous solution) directly with sodium hypochlorite (NaClO) aqueous solution has a serious problem that dangerous chlorine gas (Cl ² ) is generated at the time of mixing, and furthermore, pH adjustment. However, there are various problems in the process management, for example, it is troublesome.

An object of the present invention is to solve the above-mentioned problems, and requires less addition of chemicals such as hypochloric acid and hydrochloric acid as compared with the mixing method, and the pH is 3 to 7 safely and efficiently, preferably. Is to provide a method for producing a hypochlorous acid sterilizing water in the range of 5 to 6.5.

[Means for solving the problem]

The object of the present invention is to introduce water into an electrolytic cell having an electrolytic membrane disposed between a positive electrode and a negative electrode, add hypochlorite to water in an anode compartment, and add hydrochloric acid or the like to water in a cathode compartment. The acid is added, and the pH of the electrolytic hypochlorous acid aqueous solution generated in the anode chamber is adjusted to approximately 3 to 9, and the pH of the electrolytic water generated in the cathode chamber is adjusted to approximately 4 to 7. After the water is electrolyzed, the electrolyzed water in the anode chamber and the cathode chamber is mixed to obtain an aqueous electrolytic hypochlorous acid solution having a pH of about 3 to 7.

[Function of the invention]

In the present invention, Na is added to water in the anode chamber of an electrolytic cell partitioned by an electrolytic diaphragm.
When ClO is added and HCl is added to the water in the cathode compartment and electrolysis is performed, the pH value of the aqueous solution of NaClO in the anode compartment decreases, while the H value in the cathode compartment decreases.
The aqueous Cl solution utilizes the fact that the pH value is increased by neutralization.

That is, a high electrolysis voltage is usually required to electrolyze water containing sodium hypochlorite added to the anode chamber so that the pH becomes 3 to 9. However, in the present invention, the water in the cathode chamber is simultaneously added with hydrochloric acid such as HCl. Hydrochloric acid HCl in the cathode compartment
Some of them move to the anode compartment, which lowers the pH of the anode compartment. Thus, the water in the anode compartment can achieve a pH of 3-9 at a lower current, ie, a lower voltage. In addition, since Na ⁺ moves from the anode chamber in the cathode chamber due to electrolysis, the pH value of the aqueous HCl solution in the cathode chamber increases due to the action of Na ⁺ . That is, the water in the cathode compartment is neutralized to a pH of 4 to 7 at which no chlorine gas is generated even when mixed with the water in the anode compartment.

Therefore, by mixing the electrolyzed water in both electrode chambers, the pH at which almost 80% or more of the residual chlorine is present in the form of HClO
Water having a strong sterilizing power of 3 to 7 can be obtained without generating chlorine gas. In this electrolyzed water, the entire amount of raw water used is subjected to electrolysis.

That is, according to the present invention, in order to obtain sterilized water having a pH value of 3 to 7 from a NaClO solution having a pH value larger than 9, first, the water in the anode chamber is lowered to pH 3 to 9 by the action of electrolysis, and then the electrolytic water and The entire electrolyzed water is lowered to pH 3 to 7 by the mixing action with the electrolyzed water having a pH of 4 to 7 generated in the cathode chamber of the electrolytic cell. For this reason, the electric power can be reduced as compared with the case where the pH is lowered to 3 to 7 only by the electrolytic action.

Here, the reason for specifying the pH value of the cathode chamber at 4 to 7 is that
If the value is less than 4, chlorine gas may be generated at the time of mixing. On the other hand, if the pH value is more than 7, the pH of the electrolytic water from the anode chamber is lowered when mixed with the electrolytic water from the anode chamber 5. This is because work is lost.

Further, the reason for specifying the pH value of the anode chamber to be 3 to 9 is that if the pH value is smaller than 3, HClO becomes unstable, while the pH value is 9 to 9.
If it is larger, the desired pH value, that is, pH 3 to 7, cannot be obtained when mixed with weak acidic water in the cathode chamber.

Sterile water of this kind pH value greater than 7 and ClO ^- decreased bactericidal effect increases, while, pH value is less than 3 and HClO
Is unstable, but in the present invention, pH 3
Of the remaining chlorine in the water is more than 80%
It exists in the form of HClO and has a high bactericidal effect. In addition, since the entire amount of raw water is subjected to the electrolytic action, clusters of water molecules are reduced and the penetrating action is good.

(Example of the invention)

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view for explaining the method of the present invention. In an electrolytic cell 1, a negative electrode 2 and a positive electrode 3 are arranged to face each other. An anode chamber 3 'is partitioned, the raw water such as tap water introduced from the water supply pipe 5 is electrolyzed, and the electrolyzed water generated in both electrode chambers is separated into a pair of discharge pipes 6,
While draining from 7, the drain lines 6, 7 are merged, preferably via a valve mixer 8 capable of controlling the flow rate,
The water is drained from the sterilizing water intake pipe 9.

Thus, according to the present invention, as shown in the figure, the hypochlorite such as sodium hypochlorite NaClO is preferably added to the water in the anode chamber 3 'of the electrolytic cell 1, and the water in the cathode chamber 2' is added to the water. Preferably, an acid such as hydrochloric acid HCl is added, and the pH of the electrolyzed water in the anode chamber 3 'is about 3 to 9 and the pH of the electrolyzed water in the cathode chamber 2' is 4 to 7. The electrolyzed water in the electrolytic cell is electrolyzed, and the obtained electrolyzed water in the anode chamber 3 'and the electrolyzed water in the cathode chamber are combined and mixed to have a pH of about 3 to 7, preferably 5 to 5.
It is produced as hypochlorite-containing sterilizing water of ~ 6.5.

For this reason, a pipe 10a is provided between the sodium hypochlorite solution tank 10 and the anode chamber 3 ', and the NaClO solution is injected into the anode chamber 3' via the pump 10b and the metering valve 10c. Similarly, a pipe 11a is also provided between the hydrochloric acid tank 11 and the cathode chamber 2 ', and HCl is injected into the cathode chamber 2' via a pump 11b and a metering valve 11c.

As shown in FIG. 1, the electrolytic cell 1 may be a flow-through type electrolytic cell for performing electrolysis while continuously supplying and discharging water, or may be a batch type electrolytic cell. In this case, a constant flow valve 12 is provided in the water supply passage 5 and the flow ratio between the cathode chamber and the anode chamber is set to, for example, 1: 2 or 1: 3.
And the amount of raw water introduced into the electrolytic cell per unit time is known. Further, desirably, pH measuring devices 14 and 13 may be provided in the discharge pipes 6 and 7 on the sterile water use side.

Sodium hypochlorite (NaClO) is, for example, 12%
A solution is used, and the solution is added to the anode chamber 3 'of the electrolytic cell, and a constant flow valve is charged through the constant flow valve 10c so as to be mixed with the water of the electrolytic cell 1 at a predetermined ratio.

Thus, NaClO is added to the water in the anode chamber 3 'and HCl is added to the water in the cathode chamber 2', and a DC voltage is applied to the electrodes 2 and 3 of the electrolytic cell 1, so that the electrolytic water in the anode chamber 3 ' Electrolysis is performed so that the water in the cathode chamber 2 ′ becomes pH 4 to 7 and the pH in the cathode chamber 2 ′ becomes pH 4 to 7.

The addition amount of hydrochloric acid HCl is adjusted so that the whole of the two electrolyzed waters mixed after the electrolysis has a pH of 3 to 7.

As a result of the above electrolysis, sodium ions Na ⁺ are dissociated from NaClO added to the water in the anode compartment 3 ′ and move to the cathode compartment 2 ′ through the electrolytic diaphragm 4, and remain in the water in the anode compartment 3 ′ as shown in FIG. free chlorine hypochlorous acid (HClO) or OCl ^- will be present in the form of.

On the other hand, HCl added to the water in the cathode chamber 2 '
⁺ And Cl ^- are dissociated into, Cl ^- together are moved to the anode chamber 3 'through the electrolyte membrane 4, lowering the pH of the electrolytic water of the anode chamber,
The electrolyzed water itself in the cathode chamber 2 'is neutralized to a pH of 4 to 7 by a neutralizing action.

In the above electrolysis, the pH of the electrolytic water in the anode chamber 3 'is adjusted by adjusting the amount of HCl added to the cathode chamber 2' and the electrolysis voltage. That is, the cathode compartment 2 'HCl introduced in the H ⁺ and Cl by electrolysis ^- dissociated into, Cl ^- anode chamber 3' addition to being provided to move the the generation of HClO in the electrolytic water in the anode chamber 3 ' Since the water in the anode chamber is reduced to a pH of 3 to 9, the electrolysis voltage can be lowered accordingly.

It is more desirable that the supply amount of hydrochloric acid be automatically controlled based on the measured pH value of the sterilizing water.

Thus, the present invention provides a pH of 3 to
By mixing and mixing the anode chamber-side electrolyzed water 9 and the cathode chamber-side electrolyzed water having a pH of 4 to 7 through a mixing valve 8 whose ratio can be controlled, the pH is almost 3 to 7, preferably from the water pipe 9. Produces 5-6.5 hypochlorite sterilized water.

This hypochlorous acid water has a high bactericidal activity because 80% or more, preferably 95% or more of the residual free chlorine is present in the form of HClO.
Therefore, even if the residual chlorine concentration is as low as about 30 to 60 ppm, it can be provided as a sufficiently effective sterilizing water.

〔The invention's effect〕

The present invention mixes the electrolyzed hypochlorous acid solution of pH 3 to 9 generated in the anode compartment with the electrolyzed water of the cathode compartment neutralized to pH 4 to 7, so that the germicidal activity can be performed at a low concentration without generating chlorine gas. It is possible to obtain a hypochlorous acid sterilizing water having high strength, and it is safe and efficient.

In particular, although the present invention has the effect of lowering the pH of the anode compartment at a relatively low voltage by adding HCl to the cathode compartment, in addition, even when the electrolyzed water in the anode compartment is on the alkaline side of pH 8,9, the cathodic compartment is added. The pH is adjusted to 3 to 7 by merging the electrolyzed waters, so that the electrolysis voltage can be lowered accordingly and power can be saved.

Further, since the whole amount of the sterilized water of the present invention is subjected to the electrolytic action, the clusters of water molecules become fine and the osmotic action is good.
Therefore, it is particularly effective for sterilizing foods and the like.

Furthermore, since the amount of HClO is determined by the amount of addition of NaClO, etc., the desired minimum guaranteed value of the residual chlorine concentration of hypochlorous acid water can be easily obtained by calculation from the supply amount of raw water and the amount of NaClO added thereto. And the pH of the electrolytic current changes
Since the alarm signal of the value is provided, the condition of the pH value can be always grasped, and the management is easy.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining the method of the present invention, and FIG. 2 is a graph showing the relationship between the residual free chlorine abundance ratio of an aqueous solution of hypochlorous acid and the pH of the solution. 1 ... Electrolyzer, 2 '... Cathode room, 3' ... Anode room, 4 ...
... Electrolysis membrane, 5 ... Water supply line, 6,7 ... Drainage line, 8 ...
… Flow ratio control valve mixer, 9… Intake line, 10…
NaClO tank, 11… HCl tank.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideyuki Kitamura 23-15 Suzukocho, Kamaishi City, Iwate Prefecture Inside Nippon Steel Corporation Kamaishi Works (72) Inventor Katsue Oshima 2-6 Otemachi, Chiyoda-ku, Tokyo No. 3 In-house Nippon Steel Corporation (56) References JP-A-3-258392 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C02F 1/46-1/48 C02F 1/76

Claims (1)

(57) [Claims] (1) Raw water is introduced into an electrolytic cell having an electrolytic diaphragm disposed between a positive electrode and a negative electrode, hypochlorite is added to water in an anode chamber, and acids such as hydrochloric acid are added to water in a cathode chamber. And the pH of the electrolytic hypochlorous acid aqueous solution generated in the anode chamber is approximately 3 to 9
In addition, the pH of the electrolyzed water generated in the cathode chamber is approximately 4 to 7
After electrolyzing the water in the electrolytic cell, the electrolyzed water in the anode chamber and the cathode chamber is mixed to obtain an electrolytic aqueous solution of hypochlorous acid having a pH of about 3 to 7. A method for producing chlorite-containing sterilized water.