JPH108281A - Electrolytic cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress production of ozone and to sufficiently maintain the sterilizing effect of a strong acid water by forming a two-layer structure of a platinum plating layer and an iridium plating layer on the surface of a titanium electrode base body. SOLUTION: The electrode used for electrolysis of water has such structure that consists of a titanium base body 10, a platinum plating layer 11 on the titanium surface, and further an iridium plating layer 12 on the surface of the platinum layer. Instead of iridium for the layer 12, palladium or rhodium can be used. When only a platinum plating layer is formed as a conventional method, toxic ozone is produced by the catalytic effect of the platinum. By covering the surface of the platinum with a noble metal such as iridium, the catalytic effect of platinum can be suppressed to avoid production of ozone. The strong acid water produced on the anode contains a large amt. of hypochlorous acid by the catalytic effect of iridium, which has a strong sterilizing effect and is harmless.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a water electrolysis tank,
In particular, it relates to an electrode structure based on titanium.

[0002]

2. Description of the Related Art Recently, in the fields of medicine, foods, etc., attention has been paid to techniques for using functional water for the purpose of sterilization, disinfection, washing, bleaching, deodorization, and the like. This functional water is generated by the electrolysis of water.However, when electrolyzing water with a trace amount of salt added, platinum is conventionally plated on the surface of the titanium substrate by plating, etc. Plated electrodes were used.

However, according to this conventional technique, although the dissolution of the electrode is suppressed, there is a serious disadvantage that highly toxic ozone is generated at the anode due to the electrolysis of the saline solution. Further, there is a disadvantage that the sterilizing ability of the strongly acidic water generated at the anode is not sufficient.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrolytic cell which can be safely used in any installation environment with less toxic ozone generated, and has a strong sterilization holding power. .

[0005]

The electrolytic cell according to the present invention for solving this problem has an electrode structure for electrolyzing water,
It is characterized in that a double layer of a platinum plating layer and an iridium plating layer or a composite plating layer of platinum and iridium is provided on the surface of titanium as a base material. Iridium can be implemented by replacing it with a noble metal equivalent to this. The noble metal equivalent to iridium (Ir) refers to palladium (Pb), rhodium (Rh), ruthenium (Ru), and osmium (Os).

[0006]

In general, platinum is often used as a catalyst, and when only platinum plating is applied as an electrode structure for water electrolysis as in the conventional example, highly toxic ozone is generated due to the catalytic action of platinum. It seems to happen. In the present invention, the catalytic action of platinum is suppressed by covering the surface of platinum with a noble metal such as iridium, thereby eliminating the generation of ozone.

[0007] The strongly acidic water generated from the anode contains a large amount of hypochlorous acid due to the catalytic action of iridium and the like, which has strong sterilizing power and is harmless. This hypochlorous acid
(Hocl) is obtained by electrolyzing Nacl (salt) in saline
It becomes _two gases, and this Cl ₂ is produced by reacting with H ₂ O (water).

[0008]

FIG. 1 is a longitudinal sectional view of an example of an electrolytic cell to which the present invention is applied. A diaphragm 3 is stretched between opposing positive and negative electrodes 1 and 2 so as to be divided into an anode area 4 and a cathode area 5.
A supply pipe 6 is provided for supplying both to the anode region 5 and the cathode region 5, an acid water take-out tube 7 is provided above the anode region 4 for taking out acidic water generated by the electrolysis, and above the cathode region 5. An alkaline water extraction pipe 8 for extracting alkaline water generated by the electrolysis is provided.

The numerical example of the embodiment is as follows. The size of the electrode plate is 20 cm × 14 cm, the distance between the electrodes is 6 mm, the voltage applied between the electrodes is 12 volts, and the salt concentration of the weak saline supplied from the supply pipe is 0.07%. The flow rate was 2 liters per minute.

FIG. 2 is a schematic diagram of the electrode structure of the electrodes 1 and 2. In the embodiment shown in FIG. 1A, a platinum plating layer 11 is provided on the surface of titanium 10 as a base material, and an iridium plating layer 12 is further provided on the surface. The thickness of the platinum plating layer 11 is about 0.5 μm, and the thickness of the iridium plating layer 12 is 0.1 μm or more, preferably 0.5 μm.
μm or more, more preferably 1.0 μm or more.

The material of the plating layer 12 is iridium (I
r) instead of palladium (Pb), rhodium (Rh),
Ruthenium (Ru) and osmium (Os) can be used.

In the embodiment shown in FIG. 1B, a composite plating layer 13 of platinum and iridium is formed on the surface of titanium 10 as a base material.
Is provided. The thickness of the composite plating layer 13 is 0.1 μm or more, preferably 0.5 μm or more, and more preferably 1.0 μm or more. In addition, Irijumu (I
r) can be implemented by a composite plating layer in which palladium (Pb), rhodium (Rh), ruthenium (Ru), and osmium (Os) are substituted.

[0013]

[Embodiment 1] 1mm thick titanium as the base material,
Using an electrode having a two-layer plating structure of a platinum plating layer 0.5 having a thickness of 0.5 μm and an iridium plating layer 12 having a thickness of 0.5 μm, a flow rate of 2.0 l of a salt solution having a salt addition concentration of 0.07% was used.
Per minute, and electrolysis was performed under the condition of a voltage between electrodes of 12 V. The current during electrolysis was 9 A, the amount of acidic water generated at the anode was 1.0 l / min, and the amount of alkaline water generated at the cathode was 1.0 l / min. The RH value of the acidic water, the ORP value of the acidic water (redox potential), the ozone gas concentration, the residual chlorine concentration, and the ozone concentration of the acidic water were as shown in Table 1, respectively.

The concentration of ozone gas is the concentration of ozone gas contained in the gas component discharged from the anode side of the electrolytic cell, and is measured using a gas phase ozone concentration measuring device EG-2001R manufactured by Ebara Corporation. It was measured. The maximum scale of this instrument is 200 ppm. The ozone concentration in the acidic water is a liquid ozone concentration contained in the acidic water obtained from the anode side of the electrolytic cell, and was measured using a liquid phase ozone concentration meter Model OZM-7000L manufactured by Okitronics.

[0015]

[Table 1]

Embodiment 2 FIG. Using a 1 mm thick titanium base material, platinum-iridium (weight ratio: 1: 1) composite plating layer 13 electrode having a thickness of 1 μm, and adding a salt concentration of 0.0
Electrolysis was carried out using 7% saline under the same conditions as in Example 1. The measured values were as shown in Table 1 using the same measuring instrument.

[0017]

Table 1 shows a list of test data of Examples 1 and 2 of the present invention described above and Comparative Examples 1 and 2.
Each of the conventional examples 1 and 2 uses a 1-mm-thick titanium base material and an electrode provided with a 1-μm-thick platinum-only plating layer. Conventional example 2 is the same as the embodiment of the present invention.
The test was performed using the same setting conditions and the same measurement conditions as in the example of the present invention using 07% saline. Further, in Conventional Example 1, water containing no salt was used, and therefore, the voltage applied between the electrodes was increased to 30V. Nevertheless, the current during electrolytic decomposition was as small as 4 A, the amount of acidic water produced was 0.3 l / min, and the amount of alkaline water produced was 1.7 l / min.
Minutes.

According to the test data, the measured value of the conventional example 2 under the same conditions as in the embodiment of the present invention was 200 ppm or more, which is more than the measurable range, with respect to the concentration of ozone gas discharged from the anode side. In the embodiment of the present invention, 0.
7 ppm, 0.5 ppm, 1/300 to 1/40
It can be seen that it has dropped sharply to zero. Further, regarding the ozone concentration of the acidic water in the water extracted to the acidic water extraction pipe 7,
While 0.723 mg / L of ozone was detected in the conventional example, according to the embodiment of the present invention, both of Examples 1 and 2 were 0 mg / L and no ozone was detected.

Next, a test was conducted on the ability to maintain the oxidation-reduction potential, which is an important index for evaluating the sterilizing power of the strongly acidic water obtained by the present invention. According to Table 1, the measured value 11 of the conventional example is shown.
Example 1171m of the present invention for 93mV and 1165mV
V, 1170 mV, no significant difference was observed. However, when the change in the oxidation-reduction potential when the organic substance containing a large amount of amino acid and soy sauce were added to the strongly acidic water was measured, the data shown in FIG. 3 was obtained. According to this data, the oxidation-reduction potential (m
A monotonous decrease in V) was observed. Then, when comparing the attached amount of the organic substance lowered to the oxidation-reduction potential 1050 mV which is considered to be the sterilization limit value, Conventional Example 1 is 100 ppm and Conventional Example 2 is 215 ppm, whereas Example 1 is 42 ppm.
It extended to 0 ppm, demonstrating that the bactericidal power retention ability was extremely strong.

As is clear from the above test data, according to the present invention, the generation of highly toxic ozone is almost completely suppressed, the safety is drastically improved, and the sustainability of the strong bactericidal activity is further improved. This makes it possible to obtain at low cost functional water useful for applications such as sterilization, disinfection, washing, bleaching, and deodorization in the medical and food fields.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an electrolytic cell to which the present invention is applied.

FIG. 2 is a view schematically showing an electrode structure according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of an effect of the present invention.

[Explanation of symbols]

 10 ··· titanium (base material) 11 ··· platinum plating layer 12 ··· iridium plating layer 13 ··· composite plating layer

Claims (2)

[Claims] 1. An electrode structure for electrolyzing water, wherein platinum is applied to a surface of titanium as a base material, and iridium or a noble metal plating equivalent thereto is applied to the surface. Tank. 2. An electrolytic cell having an electrode structure for electrolyzing water, wherein a composite plating of platinum and iridium or a noble metal equivalent thereto is applied to the surface of titanium as a base material.