JPH10316403A - Active oxygen generation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate active oxygen continuously and effectively without having configurational restriction of polyaniline by passing direct current in water between a cathode consisting of a conductive material coated with a conductive composition composed of the powder and/or fiber of a conductive material, a binder and a polyaniline and a counter electrode to cathodically reduce dissolved oxygen on the coated surface. SOLUTION: The surface of a conductive material is coated with a conductive composition composed of 10-60 wt.% of the powder and/or fiber of a conductive material, 20-85 wt.% of a binder and 1-40 wt.% of a polyaniline to obtain a cathode. Direct current is applied between the cathode and a counter electrode in water where oxygen is dissolved to cathodically reduce the dissolved oxygen on the surface of the coat, and thus, oxygen is generated. Oxidized polyaniline after active oxygen generation being reversibly returned to reduced polyaniline by applying energy from outside, the active oxygen can be generated continuously and effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for generating active oxygen in water. Active oxygen is bacteriostatic, antibacterial,
It is effective for sterilization, deodorization, or decomposition of organic substances.

[0002]

2. Description of the Related Art Products that perform antibacterial, antifungal, or deodorizing utilizing a redox reaction by the photocatalytic action of titanium dioxide are becoming widespread. This is because light energy generates holes on the surface of titanium oxide. OH ^- steal of electronic,
It is based on the principle that organic matter is decomposed by the resulting .OH (hydroxyl radical) or the growth of bacteria is prevented.

[0003] On the other hand, one of the present inventors has previously stated that polyaniline, which is one of the conductive polymers, preferentially reduces oxygen in water to give active oxygen / O _{2 which has} stronger oxidizing power than hydroxy radical. (Superoxide anion radical)
And an active oxygen generating agent and a method for generating active oxygen using the same (Japanese Patent Application No. 7-338347).
No.).

[0004] Polyaniline is a conductive polymer that reversibly changes between a reduced form and an oxidized form by the transfer of electrons, and has an electrocatalytic ability to catalyze a redox reaction that is an electron transfer reaction. There is. When polyaniline is present at the cathode, it catalyzes an electrode reaction that reduces oxygen to active oxygen. Therefore, if electrons are supplied to the polyaniline by applying a reduction potential electrically, the supplied electrons should be capable of reducing dissolved oxygen to continuously generate active oxygen.

[0005] However, polyaniline is usually in the form of a powder, and its shape is restricted even if it attempts to utilize its excellent ability to generate active oxygen. As a method of coating polyaniline on a flat surface, an electrolytic polymerization method of aniline in a sulfuric acid aqueous solution can be considered, but this method is to deposit polyaniline on the surface of the conductor by an electrochemical reaction, which was generated by the deposition. The adhesion of the coating is not always good. In addition, there are restrictions on the conditions for performing the electropolymerization, and the base material to be coated must be a conductive material, and must not have a complicated shape in order to make the current distribution uniform.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, an object of the present invention is to eliminate the geometrical restrictions involved in directly using polyaniline as a catalyst for an electrode reaction, and to provide a continuous method. It is to provide a method for efficiently generating active oxygen.

[0007]

The method for generating active oxygen of the present invention has two aspects. One is to coat the surface of the conductive material with a conductive material powder and / or a conductive composition consisting of fibers, a binder and polyaniline, and use this coating as a cathode in water in which oxygen is dissolved. The method is characterized in that a direct current is passed between the electrode and the counter electrode, and active oxygen is generated by performing a cathodic reduction of the dissolved oxygen on the coating surface. Another method is to coat a metal plating layer containing polyaniline on the surface of a conductive substance, and use this coating as a cathode to pass a direct current between the counter electrode and water in oxygen-dissolved water. Is subjected to cathodic reduction on the coating surface to generate active oxygen.

[0008]

[Action] active oxygen method of the present invention, oxygen is oxygen is reduced by the liquid and polyaniline dissolved contacts, superoxide anion radical ^- the principle of generating a (· O _2). Polyaniline has an oxidized form and a reduced form. The reduced form polyaniline donates an electron to dissolved oxygen, and a superoxide anion radical (· O ₂ ⁻ )
Generate The reduced polyaniline emits electrons, and becomes itself an oxidized polyaniline. The reason why the coating layer acts as the cathode in the present invention is to provide electrons to the oxidized polyaniline after generating the active oxygen and return it to the reduced polyaniline having oxygen reducing ability.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a base material on which a coating containing polyaniline is applied must be a conductive material in order to smoothly supply electrons to polyaniline. When the base material is a non-metal, it is necessary to provide a conductive layer on the surface and apply a coating containing polyaniline thereon.

The binder used in the composition of the first aspect of the present invention is for fixing a conductive substance for transferring electrons supplied from the base material to the polyaniline together with the polyaniline on the surface of the base material. A thermoplastic resin,
A thermosetting resin and a material selected from natural or synthetic rubber are used.

The conductive material is one or two selected from graphite, carbon black, metal powder and fiber.
It consists of more than one kind of material. The conductive substance is desirably fine particles having a particle size of about submicron to about 5 μm. In particular, in order to ensure electrical conductivity, a combination of flaky graphite particles and fine powder carbon particles is used. Is preferred.

In the conductive composition containing polyaniline, the mixing ratio of the conductive substance, the binder and the polyaniline is selected from the range of 10 to 60:20 to 85: 1 to 40 by weight. When a metal is used as the conductive material, the ratio is 15 to 40:50 to 85:
The range of 1 to 10 is appropriate, and when a carbon-based material is used, 30 to 50:30 to 50: 5 to 20 is appropriate.

The conductive material is used in an amount of 70 to 10 of the binder amount.
It is preferably added at a ratio of 0% by weight. Below this range, the electrical conductivity is insufficient, and the coating does not sufficiently exhibit the active oxygen generating ability. Further, when a conductive substance is added in this range or more, the strength of the coating may be reduced and the coating may not be easily formed, or the formed coating may be easily broken.

The amount of polyaniline can be in the range of 1 to 40% by weight of the coating composition, but is preferably 5 to 40% by weight.
-20% by weight. When the content is less than 5% by weight, when the amount of dissolved oxygen is as low as about 10 ppm, the ability to generate active oxygen is significantly reduced. On the other hand, since polyaniline is an expensive material, it can only be used if a small amount is used. Even if it is added in an amount of 20% by weight or more, the effect is saturated.

As the metal plating in the second embodiment of the present invention, Ni plating is optimal. In addition, Cu, A
Similar effects can be expected by plating with g or an alloy thereof. The plating method is not particularly limited, but is preferably electroplating.

In order to obtain a plating coating containing polyaniline particles, electroplating may be performed with the particles dispersed in a plating bath. At this time, the polyaniline particles have a particle size of 0.1.
Those having a particle size distribution of about 1 to 5 μm are preferred. However, particles of polyaniline usually have an average of 20% due to aggregation.
It is as large as about μm. Polyaniline has a specific gravity of 1.2. If the specific gravity of the plating bath is adjusted by adding some kind of supporting electrolyte or sulfate of the plating metal, and stirring is performed, even if it is 5 μm or more, it is uniformly taken into the plating layer. Thus, a coating layer in which polyaniline particles are dispersed is obtained. Without such adjustment, the particles settle down in the lower part of the plating bath and the distribution of the polyaniline particles in the coating layer becomes uneven even if the stirring is performed.

The current density suitable for the plating operation varies depending on the plating bath, but it is preferable to select a current density in a range where the plating current efficiency is 60% or more. If it is 60% or less, hydrogen is generated by a side reaction, so that the polyaniline particles are less likely to approach the plating layer, and the amount taken in is reduced.

As a method of using a conductive composition containing a polyaniline or a plating layer as a cathode and passing a DC current between the cathode and a counter electrode, a method using an external power supply, a method using zinc, magnesium, aluminum, calcium or the like can be used. There is a method of forming a battery by a combination with a suitable metal. In principle, the battery formation method is based on the principle that zinc, magnesium, and the like are naturally dissolved, and electrons released with the dissolution are transferred to polyaniline and used for oxygen reduction.

[0019]

【Example】

[Example 1] A mixture obtained by mixing carbon powder and graphite powder at a weight ratio of 1: 1 was used as a conductive substance,
Silicone rubber was used as a binder and kneaded with polyaniline at a compounding ratio shown in Table 1. The surface of the blasted Ti plate was covered with the kneaded material.

Ingredients No. 1 No. 2 Comparative Example 1 Comparative Example 2 Polyaniline 15 1550 -graphite / carbon 40 35-50 silicon rubber 45 50 50 50 Next, this coating was used as a cathode and a platinum plate was used as an anode, .9
The electrolysis was performed in an aqueous NaCl solution, and the amount of generated active oxygen was examined using the amount of generated hydrogen peroxide as an index.
The use of hydrogen peroxide as an index is based on the principle that hydrogen peroxide is generated from active oxygen (excluding hydrogen peroxide) by a disproportionation reaction. The quantitative determination of hydrogen peroxide was performed by an electrochemical method. Specifically, microhole electrodes (K. Morita and Y. Shimizu, Anal. Chem., 61, 15)
9, 1989), and when measuring at a constant potential,
The average value of the two absolute values of the reduction current value to water at 0.6 V and the oxidation current value to oxygen at 0.9 V was used.

FIG. 1 shows the results. The vertical axis in the figure is the amount of hydrogen peroxide generated per unit area per unit time, and is represented by pl (picoliter). As can be seen from this figure, in Comparative Example 1 containing no conductive substance, the amount of generation at a current density of 100 μA / cm ² was zero, and in Comparative Example 2 containing no polyaniline, 0.28 pl / cm ² .
whereas a min / cm ^2, when according to the method of the present invention was respectively about 1.2 and 0.6pl / min / cm ² in No.1 and No.2.

Example 2 A powder obtained by mixing a carbon powder and a graphite powder at a weight ratio of 1: 1 as a conductive substance, chloroprene rubber as a binder, and polyaniline and a compound as shown in Table 2 were used. Kneaded in ratio. The surface of the blasted Ti plate was covered with the kneaded material.

Ingredients No. 3 No. 4 No. 5 Comparative Example 3 Polyaniline 10 520-Graphite / Carbon 45 45 30 50 Chloroprene 45 50 40 50 As in Example 1, electric power was applied in a 0.9% NaCl aqueous solution. Decomposition was performed, and the amount of hydrogen peroxide of active oxygen generated was examined as an index. In Comparative Example 3 containing no polyaniline, the amount of active oxygen generated was zero at a current density of 100 μA / cm ² , but in Examples of the present invention, No. 3 and No. 4
And in No. 5 were about 0.8, 0.3 and 1.4 pl / min / cm ² , respectively.

Example 3 Using the cathode sample No. 1 manufactured in Example 1, the same electrolysis as in Example 1 was performed for tap water, and the amount of generated active oxygen was reduced. The investigation was performed using the amount of hydrogen oxide produced as an index. The results are shown in FIG.
As shown in the graph of FIG. 2, the generation amount at 200 μA / cm ² was 1.85 pl / min / cm ² .

Example 4 240 g of nickel sulfate hexahydrate
/ Aniline, 40 g / l of nickel chloride, and 30 g / l of boric acid were dispersed with polyaniline particles at a ratio of 50 g / l. Using this as a plating bath, electrolysis was performed at a current density of 5 mA / cm ² for 15 minutes to obtain a nickel plating coating in which polyaniline was dispersed on the surface of the nickel plate.

The coating is used as a cathode, the platinum plate is used as an anode,
Electrolysis was performed in a 0.9% NaCl aqueous solution, and the amount of generated active oxygen was examined using the amount of generated hydrogen peroxide as an index. The amount of hydrogen peroxide generated at 100 μA / cm ² is 0.4 pl
/ min / cm ² . The results are shown in FIG.

[0027]

According to the method for generating active oxygen according to the present invention, the use of polyaniline solves the geometrical restriction, and the reduced polyaniline is generated by the external energy of oxidized polyaniline after generating active oxygen. , Active oxygen can be continuously and efficiently generated. According to the method of the present invention, depending on the type and shape of the base material to be coated, a coating of a conductive composition in which a conductive substance and polyaniline are integrated with a polymer binder, and a coating in which polyaniline is dispersed in a metal plating layer. Can be selected. As described above, the present invention makes it possible to effectively utilize the excellent active oxygen generating ability of polyaniline.

[Brief description of the drawings]

FIG. 1 shows data of an example of the present invention, which is 0.9%
5 is a graph showing the relationship between the cathode current density and the amount of hydrogen peroxide generated on a mixture coating of polyaniline, graphite / carbon powder, and silicone rubber in an aqueous NaCl solution.

2 is a graph showing the relationship between the cathode current density and the amount of generated hydrogen peroxide when the 0.9% NaCl aqueous solution in the data of FIG. .

FIG. 3 is a graph showing the relationship between the cathode current density and the amount of generated hydrogen peroxide when a nickel plating layer containing polyaniline is used, which is also data of the example of the present invention.

Claims (6)

[Claims] 1. A coating of a conductive composition comprising a powder of a conductive substance and / or a fiber, a binder, and polyaniline on a surface of a conductive substance, and using the coating as a cathode, water containing oxygen dissolved therein. Wherein an active oxygen is generated by passing a direct current between the counter electrode and the cathode to reduce dissolved oxygen on the coating surface. 2. The method for generating active oxygen according to claim 1, wherein the method is carried out using at least one selected from graphite powder, carbon black, metal powder, carbon fiber and metal fiber as the conductive substance powder and / or fiber. . 3. A thermoplastic synthetic resin as a binder,
The method for generating active oxygen according to claim 1, wherein the method is carried out using a thermosetting synthetic resin and a material selected from natural or synthetic rubber. 4. The mixing ratio of the conductive substance, the binder and the polyaniline is 10 to 60:20 to 85:85 by weight.
The method for generating active oxygen according to claim 1, wherein the method is carried out using a composition selected from the range of 1 to 40. 5. A coating of a metal plating layer in which polyaniline is mixed on the surface of the conductive substance, and using this coating as a cathode, a direct current is passed between the counter electrode and water in which oxygen is dissolved, A method for generating active oxygen, comprising generating active oxygen by performing cathodic reduction of dissolved oxygen on the coating surface. 6. The method according to claim 2, wherein the metal plating layer is a Ni or Cu plating layer or a Ni alloy or Cu alloy plating layer.