JPH0639379A - Method and apparatus for removing ozone in water - Google Patents

Abstract

PURPOSE:To remove sufficiently a decomposed product with oxidative force such as remaining ozone, hydrogen peroxide etc., by irradiating water contg. ozone with an ultraviolet ray and bringing the water contg. ozone irradiated with the ultraviolet ray into contact with a palladium catalyst. CONSTITUTION:Water contg. ozone to be treated at first passes through the first flow path 3 and flows into an irradiation part 1, wherein it is irradiated with an ultraviolet ray and a part of ozone is decomposed by the ultraviolet ray. Then, the ultraviolet ray-irradiated water contg. ozone passes through the second flow path 4 and is sent to a palladium catalyst part 2 of the downstream side, where it is brought into contact with the palladium catalyst and ozone in the water is furthermore decomposed and the water wherein ozone has been decomposed passes through the third flow path 5 and is sent to a required part as a ozone-decomposed and treated water. In addition, the ultraviolet irradiation apparatus used in an ultraviolet irradiation part 1 is not especially restricted but a UV lamp is used and the palladium catalyst used at a palladium catalyst part 2 is constituted of a metal palladium and a carrier for palladium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing dissolved ozone in water, and an ozone removing apparatus. More specifically, it is used for cleaning water in the electronic industry, boiler make-up water for power generation, boiler feed water, boiler condensate, The present invention relates to a method and apparatus for removing ozone in water, which is effective in removing dissolved ozone remaining in the treated water when the treated water is subjected to ozone treatment in the manufacturing process of tap water or the like.

[0002]

2. Description of the Related Art As methods for removing ozone from water, there have been conventionally known methods such as decomposition by addition of chemicals, decomposition by activated carbon, and decomposition by ultraviolet irradiation.

The ozone can be decomposed by adding chemicals, such as a method of neutralizing by adding a reducing agent such as sodium thiosulfate to the water to be treated containing ozone, and a method of adding caustic soda to adjust the pH.
There is a method that utilizes the fact that ozone self-decomposes into oxygen by raising the temperature to make it basic.

The method using activated carbon is a method in which water to be treated and activated carbon are brought into contact with each other at a relatively low flow rate to decompose ozone by a catalytic reaction.

It is also known that ozone in water is photochemically decomposed when irradiated with ultraviolet rays.

[0006] In these methods, it is necessary to provide a treatment facility for the added chemicals, residual ozone cannot be completely removed, hydrogen peroxide is generated in the process of decomposition, and activated carbon is destroyed to generate pulverized coal. There is a problem that causes. For example, an apparatus for producing cleaning water for the electronic industry is composed of a plurality of unit processes, and among them, piping materials such as vinyl chloride, ion exchange resins, ultrafiltration membranes and reverse osmosis membranes are used. Many synthetic polymer materials are used. Such synthetic polymer materials are oxidatively deteriorated by residual ozone, and the generation of pulverized coal causes clogging of these membranes. Furthermore, the pulverized coal adsorbs a very small amount of hydrogen peroxide generated by ozone decomposition. Therefore, there is a problem that when the pulverized coal is captured by the membrane or the ion exchange resin layer, the surface of the membrane or the ion exchange resin is oxidatively deteriorated.
In this way, the components that are not completely decomposed are decomposed by oxidative decomposition due to ozone and hydrogen peroxide as a by-product, which causes deterioration of water quality and the frequency of replacement of members, which increases operating costs. And other problems have arisen.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for completely removing ozone and by-products having oxidizing power in water without adding chemicals. By using the present invention, ozone treatment of water can be incorporated into, for example, a washing water manufacturing process of the electronic industry.

[0008]

In order to achieve the above object, the present invention is to irradiate water containing ozone with ultraviolet rays, and then contact the water containing ozone irradiated with ultraviolet rays with a palladium catalyst, Dissolving hydrogen in water containing ozone or water containing ozone irradiated with ultraviolet rays.

The present invention also provides an apparatus for removing ozone in water,
A flow passage through which water containing ozone flows, an ultraviolet irradiation unit arranged along the flow passage, and a palladium catalyst unit arranged in a flow passage downstream of the ultraviolet irradiation unit. , And having a hydrogen-dissolving means on the upstream side of the ultraviolet irradiation section or in the flow path between the ultraviolet irradiation section and the palladium catalyst section.

The present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In the figure, 1 is an ultraviolet irradiation unit, 2 is a palladium catalyst unit, and the irradiation unit 1 and the catalyst unit 2 have a first flow passage 3 and a second flow passage. Road 4,
The third flow passage 5 is connected. The water containing ozone to be treated first flows into the irradiation unit 1 through the first flow passage 3 and is irradiated with ultraviolet rays, whereby a part of ozone is decomposed by ultraviolet rays.

Then, the ozone-containing water irradiated with the ultraviolet rays is sent to the palladium catalyst section 2 arranged downstream of the irradiation section 1 through the second flow passage 4, where it is brought into contact with the palladium catalyst to be submerged in water. The ozone is further decomposed. The water in which ozone is decomposed passes through the third flow passage 5 and is sent to a desired place as ozone decomposition treated water.

The UV irradiator used in the UV irradiator 1 is not particularly limited, but what is generally called a UV lamp (a lamp which emits UV having a wavelength of 170 nm to 400 nm) can be used. 30 UV rays
Irradiation at Wh / m ³ or higher accelerates ozone decomposition. Further, if the irradiation amount of ultraviolet rays is 300 W · h / m ³ or more, ozone can be completely removed, but the by-products increase. Therefore, the irradiation amount of ultraviolet rays to the water to be treated is generally preferably ³⁰ to 300 W · h / m ³ .

The palladium catalyst used in the palladium catalyst section 2 comprises metallic palladium and a palladium carrier.
Examples of the carrier include ion exchange resins, activated carbon and inorganic exchangers. The metallic palladium is preferably a fine powder which is generally used as a reduction catalyst in organic synthesis and the like. The palladium catalyst is capable of decomposing ozone which has not been completely decomposed by the ultraviolet irradiation device and byproducts having an oxidizing power such as hydrogen peroxide generated by the ultraviolet irradiation. Although the mechanism of decomposition of ozone and byproducts having oxidizing power by a palladium catalyst is not completely understood, it is considered that the decomposition is catalytically promoted. By these treatments, the products of ozonolysis finally become all oxygen (O ₂ ). O ₂ remains as dissolved oxygen in the water to be treated, or if it exceeds the solubility, it becomes bubbles and is released from the water to be treated.

The amount of water passing through the palladium catalyst portion 2 varies depending on the purpose, but when it is used for washing water in the electronics industry, it is desirable to fill the carrier with a fixed bed to pass water through SV10 to SV300.

FIG. 2 shows another embodiment of the present invention.

In this embodiment, a hydrogen supply pipe 6 is connected to the second flow passage 4 connecting the ultraviolet irradiation unit 1 and the palladium catalyst unit 2, and means for supplying hydrogen gas to the second flow passage 4 is provided. To do. The means for supplying and dissolving the hydrogen gas in the water containing ozone in the second flow passage 4 can be appropriately selected. For example, the hydrogen supply pipe 6 is simply connected to the flow passage 4 in the form of a T-shaped pipe. Hydrogen gas may be directly supplied from 6 to the inside of the flow passage 4, or the hydrogen gas can be efficiently dissolved by using an ejector or the like. By supplying hydrogen, the decomposition of ozone and by-products on the palladium catalyst is promoted, and the dissolved oxygen in the water to be treated is changed to H ₂ +1/2.
It can be removed by the reaction of O ₂ → H ₂ O. At this time, if the supply amount of hydrogen is adjusted, the dissolved oxygen concentration of the water to be treated becomes 1
It can be reduced to ppb or less.

The amount of hydrogen supplied is not particularly limited, but generally, in water containing ozone, the hydrogen concentration is 0.9 mg / l.
It is preferable to supply the above.

FIG. 3 shows still another embodiment of the present invention. In this embodiment, the hydrogen supply pipe 6 is connected to the first flow passage 3
, And hydrogen is supplied on the upstream side (previous stage) of the ultraviolet irradiation unit 1. As described above, the hydrogen adding position is arbitrary as long as it is located upstream of the palladium catalyst, and there is almost no difference in effect depending on the adding place.

Examples are shown below, but the present invention is not limited to these.

[0021]

【Example】

Example 1 Using the apparatus having the configuration shown in FIG. 1, ozone concentration of 15 p in which ozonized oxygen generated from pure oxygen as a raw material was blown
pm ozone water (dissolved oxygen concentration 20.2ppm, hydrogen peroxide is not detected) UV sterilizer (Chiyoda Kou S
Water was passed through X-1 / 2) at a UV irradiation dose of 30 W · h / m ³ . Subsequently, the water irradiated with the above ultraviolet rays was treated with palladium catalyst resin (AMBERLYST manufactured by Rohm and Haas Co.).
ER-206) is packed in a column (catalyst resin tower) filled with S
Water was passed at V120. The ozone concentration, hydrogen peroxide concentration, and dissolved oxygen concentration of the palladium catalyst resin tower treated water at this time are shown in the table.

Example 2 In the apparatus of Example 1, hydrogen gas was introduced between the ultraviolet sterilizer and the palladium catalyst resin tower using an ejector. At this time, the dissolved hydrogen concentration of the palladium catalyst resin tower inlet water was adjusted to 3.5 ppm. The ozone concentration, hydrogen peroxide concentration, and dissolved oxygen concentration of the palladium catalyst resin tower treated water at this time are shown in the table. The ozone concentration was measured with an ozone meter (Model 27505 manufactured by Orvissphere), the hydrogen peroxide concentration was titrated with potassium permanganate, and the dissolved oxygen concentration was measured with a dissolved oxygen meter (DO-30 manufactured by Toa Denpa Kogyo).
It was measured using A).

Example 3 In the apparatus of Example 1, hydrogen gas was introduced using an ejector in front of the ultraviolet sterilizer used as the ultraviolet irradiation section. As a result, the water entering the ultraviolet sterilizer was saturated with dissolved hydrogen. The ozone concentration, hydrogen peroxide concentration, and dissolved oxygen concentration of the palladium catalyst resin tower treated water at this time are shown in the table.

Comparative Example 1 The same ozone water as in Example 1 was passed through an ultraviolet sterilizer (SX-1 / 2, manufactured by Chiyoda Kogyo Co., Ltd.) at an irradiation dose of 30 W · h / m ³ . The ozone concentration, hydrogen peroxide concentration and dissolved oxygen concentration of the treated water of the ultraviolet sterilizer at this time are shown in the table.

Comparative Example 2 The same ozone water as in Example 1 was passed through an ultraviolet sterilizer (SX-1 / 2 manufactured by Chiyoda Kogyo Co., Ltd.) at an irradiation dose of 300 W · h / m ³ . The ozone concentration, hydrogen peroxide concentration and dissolved oxygen concentration of the treated water of the ultraviolet sterilizer at this time are shown in the table.

Comparative Example 3 The same ozone water having an ozone concentration of 15 ppm as in Example 1 was used as an SV.
At 40, water was passed through the activated carbon tower. The ozone concentration, hydrogen peroxide concentration and dissolved oxygen concentration of the treated water of the activated carbon tower at this time are shown in the table.

In this example, ozone was removed to some extent, but it was not as complete as in the examples of the present invention, and fine particles of activated carbon were dispersed in the treated water.

[0028]

[Table 1] As can be seen from the above results, ozone and a decomposition product such as hydrogen peroxide generated by decomposition can be completely and easily removed by combining an ultraviolet irradiation device and a palladium catalyst. A method that is more efficient than conventional methods such as UV irradiation or ozone decomposition by activated carbon, and can decompose ozone without polluting treated water without the emission of pulverized coal (fine particles), which is a problem with activated carbon. I understand that.

[0029]

INDUSTRIAL APPLICABILITY According to the present invention, by combining an ultraviolet irradiation device and a palladium catalyst as a method for decomposing dissolved ozone in water, the oxidizing power of residual ozone, hydrogen peroxide, etc. which may cause oxidative deterioration of the constituent members of the device. It is possible to sufficiently remove some decomposition products. Further, by adding hydrogen gas, dissolved oxygen can also be reduced.

By using this method, it is possible to combine the ozone treatment with an ion exchange resin, a reverse osmosis membrane, etc., which has low oxidation resistance and cannot be used in combination with the ozone treatment.

[Brief description of drawings]

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

FIG. 2 is a configuration diagram showing another embodiment of the present invention.

FIG. 3 is a configuration diagram showing still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultraviolet irradiation part 2 Palladium catalyst part 3 1st flow path 4 2nd flow path 5 3rd flow path 6 Hydrogen supply pipe

Claims (4)

[Claims] 1. Irradiating water containing ozone with ultraviolet rays,
Next, a method for removing ozone in water, which comprises contacting water containing ozone irradiated with ultraviolet rays with a palladium catalyst. 2. The ozone removing method according to claim 1, wherein hydrogen is dissolved in water containing ozone or water containing ozone irradiated with ultraviolet rays. 3. A flow passage through which water containing ozone flows, an ultraviolet ray irradiating portion arranged along the flow passage, and a palladium catalyst portion arranged in a flow passage downstream of the ultraviolet ray irradiating portion. A device for removing ozone from water. 4. The ozone removing device according to claim 3, further comprising hydrogen dissolving means on the upstream side of the ultraviolet irradiation section or in the flow passage between the ultraviolet irradiation section and the palladium catalyst section.