JPH05138171A - Electrolytic water purifier - Google Patents

Abstract

PURPOSE:To remove a buffer ion having buffer action to pH variation in water, to improve electrolytic efficiency and to easily regenerate the efficiency of a ion exchange resin. CONSTITUTION:This purifier consists of a neighboring anode chamber 10A and cathode chamber 10B interposing a membrane 11 between them, electrode plates 12 and 13 provided in an anode chamber 10A and cathode chamber 10B, an ion exchange resin 15 provided in one side or both side of the anode chamber 10A and the cathode chamber 10B, and buffer ion in water is neutralized by ion exchange action and an ion exchange resin is regenerated by ionized water Wa improved in ion concentration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic water purifier for obtaining acidic ionized water and alkaline ionized water useful for health and medical purposes.

[0002]

2. Description of the Related Art Conventionally, by electrolyzing water, its pH is changed, that is, water is oxidized on the anode side to generate acidic ionized water, and water is reduced on the cathode side to generate alkaline ionized water. Electrolytic water purifiers are known. However, in the case of obtaining acidic ionized water, for example, if carbonate ions or hydrogen carbonate ions are present in the water to be electrolyzed, there is a problem that the conventional electrolytic water purifier suppresses the pH change.

That is, in H ₂ CO ₃ carbonate, unionized molecules and ions generated by dissociation are in the next dissociation (ionization) equilibrium state in an aqueous solution. H ₂ CO ₃ ⇔ 2H ⁺ + CO ₃ ² -... (1) Further, the equilibrium constant (ionization constant) K at this time is K = [H ⁺ ] ² [CO ₃ ^2- ] / [H ₂ CO ₃ ] ... (2).

When sodium NaHCO ₃ which completely dissociates is added to this solution, the sodium hydrogen carbonate Na
HCO ₃ dissociates like NaHCO ₃ → Na ⁺ ＋ H ⁺ ＋ CO ₃ ²⁻・ ・ ・ (3), so the concentration of CO ₃ ²⁻ ion [CO ₃ ²⁻ ] increases and the above (1) The equilibrium of the formula tilts to the left side and the concentration of H ₂ CO ₃
[H ₂ CO ₃ ] also rises, the equilibrium constant K becomes a constant value, and dissociation is suppressed. Therefore, [H ₂ CO ₃ ] is equal to the initial carbon dioxide concentration C _1, and [CO ₃ ²⁻ ] is the added sodium hydrogen carbonate NaHCO ₃
Since equal to concentration C ₂ of the hydrogen ion concentration [H ^+]
2 becomes [H ⁺ ] ² = K · C ₁ / C ₂ ... (4). That is, when a common ion (CO ₃ ^{2− in the} above case) is present in the aqueous solution, the concentration of hydrogen ion H ⁺ depends on the concentration of the salt that was initially in the dissociation equilibrium state and that of the added salt Ratio. Even if a small amount of acid (hydrogen ion H ⁺ ) is added to such an aqueous solution, the pH of the aqueous solution does not change because the H ⁺ ions are combined with CO ₃ ²⁻ present in a large amount in the aqueous solution. Moreover, alkali (hydroxide ion OH ^-) is added, and the OH ^- ions is combine with H ⁺ ions, H
₂ CO ₃ dissociates and releases H ⁺ , so the pH does not change.

[0005]

Therefore, in the conventional electrolytic water purifier by the constant current method, when carbonate ions or hydrogen carbonate ions are present in the water, the pH changes due to the anodic electrolytic reaction due to the above-described buffering action. It was suppressed and the electrolysis efficiency was low. Moreover, since the concentration of carbonate ions, hydrogen carbonate ions, etc. in water varies depending on the water intake location (region), it has been difficult to obtain electrolyzed water with the same current value and the same pH. The electrolysis efficiency is the ratio (%) of the actually measured ion generation amount to the theoretical ion generation amount obtained from the flow rate of water and the current value based on Faraday's law.

The present invention has been made in view of the above problems. An object of the present invention is to improve the electrolysis efficiency by removing buffer ions in water which have a buffering action against pH change. In addition, the effect of the ion exchange resin can be easily regenerated.

[0007]

In order to solve the above problems, an electrolytic water purifier according to the present invention is provided with an anode chamber and a cathode chamber which are adjacent to each other via a porous diaphragm having fine pores, and an anode chamber and a cathode. The electrode plate is disposed in the chamber, and the ion exchange resin is disposed in one or both of the anode chamber and the cathode chamber. Further, in this configuration, it is desirable that the ion exchange resin in the anode chamber be weakly acidic and the ion exchange resin in the cathode chamber be weakly basic.

[0008]

The present invention neutralizes buffer ions in water having a buffering action against pH change by the ion exchange reaction of the ion exchange resin to produce a salt having no buffering action against pH change, thereby improving the electrolysis efficiency. To improve.
The ion exchange resin needs to be regenerated because the efficiency of ion exchange decreases with time by continuing the above ion exchange reaction, but the ion exchange resin can be regenerated by using the ions generated by electrolysis. Therefore, when the entry of raw water into the electrolyzer and the withdrawal of electrolyzed water are stopped, the ion-exchange reverse reaction occurs due to the electrolyzed water having an increased concentration, and the ion-exchange resin is automatically regenerated.

Further, by using a weakly acidic ion exchange resin in the anode chamber and a weakly basic ion exchange resin in the cathode chamber, a strong acidic or strongly basic ion exchange resin is used. It is possible to obtain a constant pH without excessively changing the pH.

[0010]

EXAMPLE Next, an electrolytic water purifier of the present invention will be described with reference to an example shown in FIG. 1. Reference numeral 10 denotes an electrolytic cell in which the inside is divided into an anode chamber 10A and a cathode chamber 10B by a diaphragm 11. Is. An anode plate 12 is provided in the anode chamber 10A, and a cathode plate 13 is provided in the cathode chamber 10B. The anode plate 12 and the cathode plate 13 are connected via a rectifier (DC power supply) 14. A porous film having innumerable micropores of about 0.1 to 5 μm is used for the diaphragm 11, and stainless steel, titanium, platinum, ferrite, carbon or the like is used for the anode plate 12 and the cathode plate 13. ..

An H ⁺ type cation exchange resin 15 is provided adjacent to the anode plate 12 in the anode chamber 10A. 1
Reference numeral 6 denotes an inlet for the untreated water W into the electrolytic cell 10, which serves as an anode chamber 10
It branches into an anode chamber side water inlet 16A connected to A and a cathode chamber side water inlet 16B connected to the cathode chamber 10B. Further, 17 is a water intake of the acidic ion water Wa from the anode chamber 10A, and 18 is a water intake of the alkaline ion water Wb from the cathode chamber 10B.

In the above structure, untreated water W from a water supply source (not shown) is branched from the water inlet 16 to 16A and 16B and supplied to the anode chamber 10A and the cathode chamber 10B of the electrolytic cell 10, respectively. At this time, the rectifier 1 which is a DC power supply
When 4 is turned on, water is oxidized by the anode plate 12 in the anode chamber 10A, that is, + electrolysis causes the following reaction. H ₂ O → 2H ⁺ + 2e ⁻ + 1 / 2O ₂ ··· (5) Further, in the cathode chamber 10B, water is reduced by the cathode plate 13, that is, − The following reactions occur by electrolysis. H ₂ O ＋ e ⁻ → OH ⁻ ＋ 1 / 2H ₂・ ・ ・ ・ ・ ・ ・ ・ (6)

The hydrogen ions H ⁺ generated in the anode chamber 10A and the hydroxide ion OH ⁻ generated in the cathode chamber 10B by this reaction are associated with water molecules having a strong polarity.
The diaphragm 11 has a size that cannot pass through the diaphragm 11 and is retained in the anode chamber 10A and the cathode chamber 10B, respectively, and water molecules freely pass through the diaphragm 11 to enable continuous electrolysis. Therefore, the concentration of hydrogen ions H ⁺ increases in the anode chamber 10A, the pH decreases, and acidic ion water Wa is generated, while the concentration of hydroxide ions OH ⁻ increases in the cathode chamber 10B. The pH rises and the alkaline water Wb is produced.

Here, if the untreated water W supplied to the anode chamber 10A contains an alkaline buffer ion such as hydrogen carbonate ion HCO ₃ ⁻ , the pH change due to the anodic electrolytic reaction of (5). Is suppressed. However, according to the present embodiment, the H ⁺ type cation exchange resin 15 is provided in the anode chamber 10A, and the H ⁺ type cation exchange resin 15 performs the following ion exchange reaction. RH ⁺ + M ⁺ → RM ⁺ + H ⁺ ... (7) (RH ⁺ is H ⁺ type ion exchange resin, M ⁺ is in water Positive ion)
Therefore, the buffer ions such as hydrogen carbonate ion HCO ₃ ⁻ contained in the water W are neutralized by the following reaction with the H ⁺ ion according to the above (7). ^{_{H + + HCO 3 - → H}} 2 CO 3 therefore ······················ (8), combine with H ⁺ ions generated in the anode chamber 10A Since hydrogen carbonate ion HCO ₃ ⁻ which hinders the pH decrease is removed, it is possible to accelerate the anodic electrolysis reaction of (5) above to obtain acidic ionized water Wa having a high H ⁺ ion concentration (low pH). it can.

As the cation exchange resin 15 continues to undergo the reaction of the above (7), the efficiency of ion exchange decreases with time, and therefore it is necessary to regenerate the effect. Therefore, when electrolysis is performed in the electrolytic cell 10 with the intake of the acidic ionized water Wa from the intake port 17 and the supply of the untreated water W from the water inlet 16A stopped, the acidic ionized water Wa in the anode chamber 10A is H ⁺ ion concentration increases and becomes highly acidic. Therefore, due to the high concentration of H ⁺ ions,
The reverse reaction of (7) occurs and the cation exchange resin 15 is regenerated.

FIG. 2 shows changes in pH in the anode chamber when acidic ionized water is obtained using the electrolytic water purifier having the structure of this embodiment and when acidic ionized water is obtained using the conventional electrolytic water purifier. It is an experimental value. As a result, in the water purifier of this example in which the H ⁺ type cation exchange resin 15 was provided in the anode chamber 10A, the pH drop was more remarkable at each current value, and the effectiveness as acidic ionized water was improved. It was confirmed to increase.

In the above embodiment, the acidic ionized water Wa is used.
The case of increasing the effectiveness of the cathode chamber 10B has been described.
When the alkali OH ⁻ ion concentration of the alkaline ionized water Wb generated in step 1 is increased, the cathode plate 13 is placed in the cathode chamber 10B.
An OH ^- type anion exchange resin is installed adjacent to. In this case, the untreated water W supplied into the cathode chamber 10B undergoes the following ion exchange by the anion exchange resin. ROH ⁻ + A ⁻ → RA ⁻ + OH ⁻ ····· (9) (ROH ⁻ is an OH ⁻ type ion exchange resin, A ⁻ is an anion in water. Therefore, acidic buffer ions such as Fe ³⁺ ions contained in the water W are neutralized by the following reaction with OH ⁻ ions according to (9) above. 3OH ⁻ + Fe ³⁺ → Fe (OH ⁻ ) ₃ ···· (10) Therefore, it combines with the OH ⁻ ions generated in the cathode chamber 10B. Since the cation components such as Fe ³⁺ , Al ³⁺ , and organic acid that hinder the pH increase are removed, the cathodic electrolysis reaction of (6) above can be promoted.

Regeneration of the anion exchange resin is similar to that of the cation exchange resin described above,
That is, O in the cathode chamber 10B is generated by electrolysis.
The OH ^- type anion exchange resin can be regenerated by increasing the H ^- ion concentration and causing the reverse reaction of the above (9).

By the way, the cation exchange resin 1 shown in FIG.
When 5 is, for example, a strongly acidic one such as a sulfonic acid group, the pH of the acidic ionized water Wa in the anode chamber 10A is 2-3.
However, it is difficult to adjust the pH of the acidic ionized water to around 5 which is said to be optimum (corresponding to the pH of human skin). Further, in this case, even if the size of the cation exchange resin 15 is adjusted, the amount of the alkaline buffer ion such as hydrogen carbonate ion HCO ₃ ⁻ contained in the water greatly changes depending on the place and time, and the acidic ion water is added. Wa
It is difficult to keep the pH constant because the pH of the is greatly affected by the amount of this buffer ion. Therefore, if a weakly acidic one such as a carboxyl group is used as the cation exchange resin 15, the weakly acidic ion exchange resin will not perform ion exchange when the pH is lowered to about 5 to 4, so that the pH is lowered. It can be kept constant, and the change in pH due to electrolysis can be easily controlled. Further, the same can be said for the anion exchange resin provided in the cathode chamber 10B, and therefore it is preferable to use a weakly basic anion exchange resin such as primary and secondary amines.

FIG. 3 shows the pH of acidic ionic water when weakly acidic Amberlite IRC-50 (trade name) is used as the cation exchange resin 15 and when strongly acidic sulfonic acid group type is used. Is measured. As a result, when a strongly acidic cation exchange resin was used, the pH dropped to 4 or less, and the pH varied greatly depending on the amount of buffer ions in water. It was confirmed that the pH was stable at about 5 when the exchange resin was used.

[0021]

As is apparent from the above description, according to the electrolytic water purifier of the present invention, water is electrolyzed while neutralizing buffer ions in water by ion exchange in the electrolytic cell. It is possible to improve the electrolysis efficiency by making a remarkable change in pH due to electrolysis. In particular, the pH can be kept constant by using a weakly acidic cation exchange resin provided on the anode plate and a weakly basic anion exchange resin provided on the cathode plate.

Further, the ion exchange resin having a weakened effect can be easily regenerated by carrying out an ion exchange reverse reaction by utilizing the ionized water having a high ion concentration in the electrolyzed electrolyzer, and has a simple constitution. Moreover, it has an excellent effect that no special maintenance work of the ion exchange resin is required.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is a graph showing changes in pH in the anode chamber with and without an ion exchange resin.

FIG. 3 is a graph showing changes in pH in the anode chamber when a weakly acidic ion exchange resin is provided and when a strongly acidic ion exchange resin is provided.

[Explanation of symbols]

10 Electrolyzer 10A Anode chamber 10B Cathode chamber 12 Anode plate (electrode plate) 13 Cathode plate (electrode plate) 15 H ⁺ type cation exchange resin W Untreated water Wa Acid ionized water Wb Alkaline ionized water

Claims (2)

[Claims] 1. An anode chamber and a cathode chamber which are adjacent to each other via a porous diaphragm having fine pores, an electrode plate arranged in the anode chamber and the cathode chamber, and one or both of the anode chamber and the cathode chamber. An electrolytic water purifier comprising an ion exchange resin arranged. 2. The electrolytic water purifier according to claim 1, wherein the ion exchange resin in the anode chamber is weakly acidic and the ion exchange resin in the cathode chamber is weakly basic.