JP4508311B2 - Adjustment method of ozone concentration - Google Patents

Description

【００１０】
第１表に見られるように、溶存オゾン濃度の高いオゾン含有水を破砕ガラスを充填したカラムに通水してガラスと接触させることにより、溶存オゾン濃度が低下し、かつ５回の溶存オゾン濃度の測定値のばらつきが１mg／リットル程度であることから、本発明方法によりオゾン含有水の溶存オゾン濃度を正確に制御し得ることが分かる。また、溶存オゾン濃度の低いオゾン含有水を通水した実施例４〜６の結果から、本発明方法は、オゾン含有排水の処理にも有効であり、実施例５と実施例６を比較すると、カラムに充填する破砕ガラスの量を増すことにより、処理水中の溶存オゾンの分解量を効果的に増大し得ることが分かる。
【００１１】
【発明の効果】
本発明方法によれば、高濃度のオゾン含有水を製造し、ごく簡単な処理により溶存オゾンを分解して、正確に安定して所望濃度のオゾン含有水に調整することができる。また、オゾン含有排水の処理においても、メンテナンスフリーの装置を用いて、溶存オゾン濃度を低減することが可能となる。
【図面の簡単な説明】
【図１】図１は、本発明方法の実施の一態様の工程系統図である。
【符号の説明】
１ 超純水タンク
２ ポンプ
３ エジェクター
４ オゾン発生器
５ 通水配管
６ ユースポイント
７ 破砕ガラス充填カラム
８ サンプリングポイント
９ サンプリングポイント[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for reducing and adjusting an ozone concentration. More specifically, the present invention relates to a method for reducing the concentration of ozone that can reduce the concentration of dissolved ozone without requiring maintenance in the treatment of wastewater containing ozone, and a wet cleaning process for electronic materials and the like. The present invention relates to a method for adjusting ozone concentration, which can easily supply ozone-containing water having a desired dissolved ozone concentration to a use point.
[0002]
[Prior art]
Removal of fine particles, organic substances, metals, and the like from the surface of electronic materials such as a semiconductor silicon substrate, a liquid crystal glass substrate, and a photomask quartz substrate is extremely important for ensuring product quality and yield. For this purpose, wet cleaning at a high temperature with a concentrated chemical solution based on hydrogen peroxide called the so-called RCA cleaning method is performed, and a mixed solution (APM) of ammonia and hydrogen peroxide solution or hydrochloric acid and hydrogen peroxide solution. A mixed solution (HPM) or the like was used. Reduces the cost of chemicals when using these cleaning methods, the cost of ultrapure water for rinsing, the cost of waste liquid treatment, the cost of air conditioning to exhaust chemical vapor and create new clean air, and use a large amount of water In recent years, the wet cleaning process has been reviewed in order to reduce environmental burdens such as mass disposal of drugs and emission of exhaust gas.
The present inventors have previously developed a gas-dissolved cleaning water for cleaning electronic materials in which ozone is dissolved in pure water. Washing water in which ozone is dissolved in pure water exhibits extremely high oxidizing power despite the low concentration of dissolved ozone of several mg / liter, and is contaminated by impurities such as organic substances and metals attached to the surface of electronic materials. It is used in the step of removing and the step of uniformly oxidizing the surface of the silicon substrate to form a chemical oxide film layer. Washing water in which ozone is dissolved in pure water has the advantage that the surface of the object to be cleaned is kept clean because it has no persistence, and it becomes high-purity water again by decomposition or removal of ozone and can be reused. However, the cleaning water in which ozone is dissolved is not easy to maintain and maintain the ozone concentration because the dissolved ozone self-decomposes with time and becomes oxygen.
On the other hand, the present inventors have found that the decrease in the dissolved ozone concentration is suppressed by supplying the ozone-containing gas and pure water while mixing them in the water pipe, and the ozone concentration is almost constant. A system for supplying ozone-containing water was developed. That is, a mixed gas of ozone and oxygen is produced by an ozone generator and fed into pure water in an ozone dissolving apparatus. The mixed gas of ozone and oxygen is mixed with pure water to be in a gas-liquid mixed state, ozone is dissolved to generate ozone-containing water, and further flows in the water flow pipe in the gas-liquid mixed state. Ozone dissolved in water changes to oxygen over time due to self-decomposition, but the decrease in dissolved ozone due to self-decomposition is compensated for by dissolving ozone in the gas phase in water. The concentration can be kept almost constant. However, even with this system, the ozone concentration may decrease when the branch piping that leads the ozone-containing water to the use point passes through a complicated piping route. Moreover, ozone-containing water having different ozone concentrations may be required depending on the use point.
In JP-A-10-57907, as a method for stably supplying ozone water having a constant concentration, the supply amount of ozone water obtained by the ozone water production means is set higher than the maximum discharge amount of ozone water. A method for controlling the amount of ozone water in the ozone water tank so as to always be within a certain range has been proposed. However, in such a method, control is complicated and a large-scale installation is required.
Ozone-containing water used in the electronics industry such as semiconductors and liquid crystals is required to have a very high purity with respect to impurities other than ozone. In addition, ozone-containing water is widely used for cleaning and sterilization in fields such as the pharmaceutical industry and food industry, but there are few methods for adjusting the dissolved ozone concentration while maintaining high purity. Therefore, there is a demand for a method for adjusting the ozone concentration, which can easily obtain ozone-containing water having a desired concentration.
On the other hand, ozone remains in the ozone-containing water used at the point of use. Like the ozone-containing water that was not used at the point of use, ozone can be decomposed using activated carbon, ultraviolet irradiation equipment, catalysts, etc. Has been done. However, ultraviolet irradiation has high equipment costs and processing costs, and the activated carbon and the catalyst deteriorate, so that they must be replaced regularly.
[0003]
[Problems to be solved by the invention]
In the treatment of wastewater containing ozone, the present invention is a use point in a method for reducing ozone concentration that can reduce dissolved ozone concentration without requiring maintenance, and in a wet cleaning process for electronic materials, etc. An object of the present invention is to provide a method for adjusting the ozone concentration, which can easily supply ozone-containing water having a desired dissolved ozone concentration.
[0004]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have brought ozone-containing water into contact with glass, thereby promoting the self-decomposition of dissolved ozone and reducing the ozone concentration. By selecting the contact condition between the contained water and the glass, it has been found that it is possible to obtain ozone-containing water having a desired concentration by controlling the decomposition amount of ozone, and to complete the present invention based on this knowledge. It came.
That is, the present invention
(1) Pack the crushed glass to be used into the crushed glass packed column to be used, change the filling amount of the crushed glass and the particle size of the crushed glass, and use the ozone-containing water at the concentration to be used. Pass water at a water speed, measure the ozone concentration of ozone-containing water after passing through the crushed glass packed column, and when the ozone concentration of ozone-containing water after passing through the crushed glass packed column reaches the desired reduced ozone concentration in the particle size of the loading and crushing glass crushing glass, ozone-containing water having a concentration of scheduled use in contact with the crushed glass packed column, the ozone-containing, wherein to Rukoto and ozone-containing water having a desired reduced ozone concentration Adjustment method of ozone concentration of water, and
(2) Ultrapure water is pumped from the ultrapure water tank to the ejector at a water flow rate that is scheduled to be used, and simultaneously, the mixed gas of ozone and oxygen is blown into the ejector by changing the supply amount of the mixed gas. By measuring the ozone concentration of the ozone-containing water before passing through the packed column and blowing it into the ejector with the amount of mixed gas supplied when the ozone concentration is scheduled to be used, the ozone-containing water with the ozone concentration scheduled to be used is crushed. The method for adjusting the ozone concentration of ozone-containing water as described in item (1), which is passed through a glass-filled column ,
Is to provide.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The ozone concentration reducing method of the present invention is to bring ozone-containing water into contact with glass. The ozone concentration adjusting method of the present invention is to bring ozone-containing water into contact with glass to obtain ozone-containing water having a desired concentration. It is. By bringing ozone-containing water into contact with glass, self-decomposition of dissolved ozone in ozone-containing water is promoted. By bringing ozone-containing wastewater into contact with glass, the dissolved ozone concentration can be reduced without requiring maintenance. Can be reduced. In addition, ozone-containing water in which ozone at a concentration higher than the desired concentration at the use point is dissolved in the electronic material cleaning step, etc., is brought into contact with the glass in the vicinity of the use point, and the amount of dissolved ozone can be reduced to the desired concentration.
There is no restriction | limiting in particular in the kind of glass used for this invention method, For example, soda lime glass, potash lime glass, borosilicate glass, lead glass, aluminosilicate glass, borate glass, phosphate glass, aluminate glass , Titanate glass, fluoride glass, chalcogen glass, and the like. In these, the borosilicate glass excellent in the chemical durability with respect to water and an acid can be used suitably.
There is no restriction | limiting in particular in the shape of the glass used for this invention method, For example, plate glass, a glass tube, a glass bead, glass fiber etc. can be mentioned. In the method of the present invention, there is no particular limitation on the method of bringing the ozone-containing water into contact with the glass. For example, by making the liquid contact material of a part of the flow path of the ozone-containing water into glass, the ozone-containing water is brought into contact with the glass. Alternatively, ozone-containing water can be brought into contact with the glass by installing a container filled with crushed glass in the flow path of the ozone-containing water. Among these, crushed glass obtained by crushing glass into several mm square is easy to handle and has a large surface area, and therefore can be suitably used.
[0006]
According to the ozone concentration adjusting method of the present invention, in an ozone dissolving apparatus, excess ozone is dissolved in pure water, and before being used at a point of use, ozone-containing water is brought into contact with glass to perform self-decomposition of ozone. And can easily adjust the concentration of ozone-containing water. Moreover, the dissolved ozone density | concentration in ozone containing waste water can be reduced easily by the same means. That is, in the contact between the ozone-containing water and the glass, the concentration of the ozone-containing water can be adjusted easily and accurately by selecting the surface area of the glass to be contacted, the contact time, and the like. The amount of ozone decomposed can be increased by means such as increasing the amount of glass brought into contact with the ozone-containing water, reducing the particle size of the crushed glass, and slowing the water flow rate. In carrying out the method of the present invention, using the crushed glass to be used, the relationship between the glass filling amount and the ozone decomposition amount, the relationship between the glass particle size and the ozone decomposition amount, the relationship between the water flow rate and the ozone decomposition amount, etc. Can be obtained experimentally in advance, and a desired ozone concentration can be obtained by controlling an arbitrary factor according to the amount of ozone to be reduced. Moreover, since the amount of ozone decomposition is also affected by the ozone concentration of ozone-containing water, it is preferable to experiment by changing the ozone concentration of ozone-containing water when grasping the relationship between the contact condition with glass and the amount of ozone decomposition. .
According to the method of the present invention, in a supply system of ozone-containing water in an electronic material factory or the like, by providing a container filled with crushed glass between the ozone-containing water production apparatus and the ozone-containing water use point, The dissolved ozone concentration of ozone-containing water having a concentration can be reduced to easily obtain ozone-containing water having a desired concentration. Since ozone-containing water must not be contaminated during contact with glass, the piping that passes ozone-containing water has very little elution of foreign substances and does not react with ozone, which has strong oxidizing power. It is preferable to use a resin tube or the like. Similarly, the container filled with crushed glass is also preferably a member having high ozone resistance. The container itself filled with the crushed glass can be made of glass.
[0007]
In the method of the present invention, the mechanism by which ozone self-decomposition is promoted by bringing ozone-containing water into contact with glass is not clear, but it is presumed that a trace amount of metal mixed in the glass is acting. However, the metal has almost no elution from the glass, and even if it is analyzed, it is below the detection limit. Therefore, even if ozone-containing water contacted with the glass is used for cleaning electronic materials, the metal is not a source of contamination. There is no fear of becoming.
FIG. 1 is a process flow diagram of one embodiment of the method of the present invention. Ultrapure water is sent from the ultrapure water tank 1 to the ejector 3 by the pump 2, and simultaneously, a mixed gas of ozone and oxygen generated by the ozone generator 4 is blown into the ejector, and into the water pipe 5 in a gas-liquid mixed state. Sent. A crushing glass packed column 7 is provided in the vicinity of the use point 6 in the water flow pipe. Sampling points 8 and 9 provided before and after the crushed glass packed column sample the ozone-containing water and measure the respective dissolved ozone concentrations, so that the ozone-containing water at the desired concentration can be obtained at the use point. Set.
When the ozone concentration reduction method of the present invention is carried out in the drainage line of ozone-containing water used at the point of use or ozone-containing water that has not been used, unlike conventional methods using activated carbon, ultraviolet irradiation, catalyst, etc., As a completely maintenance-free ozonolysis method, the dissolved ozone concentration can be reduced. When the ozone concentration adjustment method of the present invention is carried out to obtain ozone-containing water of a desired concentration, glass deteriorates like activated carbon or catalyst, unlike the conventional method of decomposing ozone by contacting with activated carbon or catalyst. In addition, there is no possibility that foreign matter is eluted and the quality of ozone-containing water is lowered.
[0008]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
Example 1
The ozone concentration of the ozone-containing water was adjusted using the apparatus shown in FIG.
Ultrapure water is sent from the ultrapure water tank 1 to the ejector 3 by a pump 2 at a flow rate of 16 liters / min. At the same time, a mixed gas of ozone and oxygen generated by the silent discharge ozone generator 4 is blown into the ejector. The mixed state was sent to the water flow pipe 5. The water flow pipe is provided with a crushed glass packed column 7 in the vicinity of the use point 6 and filled with 500 g of 1.2 mm thick glass [Corning, Pyrex 7740] crushed to approximately 3 to 5 mm square. At sampling points 8 and 9 provided before and after the crushed glass packed column, the ozone-containing water was sampled five times every hour, and the dissolved ozone concentration was measured.
The dissolved ozone concentration of ozone-containing water before passing through the crushed glass packed column was 25 to 26 mg / liter, and the dissolved ozone concentration of ozone-containing water after passing through the crushed glass packed column was 14 to 15 mg / liter.
Example 2
The same operation as in Example 1 was repeated except that the supply amount of the mixed gas of ozone and oxygen was reduced.
The dissolved ozone concentration of ozone-containing water before passing through the crushed glass packed column was 15 to 17 mg / liter, and the dissolved ozone concentration of ozone-containing water after passing through the crushed glass packed column was 8 to 9 mg / liter.
Example 3
The same operation as in Example 1 was repeated except that the supply amount of the mixed gas of ozone and oxygen was further reduced.
The dissolved ozone concentration of ozone-containing water before passing through the crushed glass packed column was 10 to 12 mg / liter, and the dissolved ozone concentration of ozone-containing water after passing through the crushed glass packed column was 6 to 7 mg / liter.
Example 4
Assuming the treatment of ozone-containing wastewater, the amount of crushed glass in the apparatus shown in FIG. 1 was increased, and the dissolved ozone concentration of the supplied ozone-containing water was reduced.
The same operation as in Example 1 was repeated except that the amount of the glass packed in the crushed glass packed column was 600 g and the supply amount of the mixed gas of ozone and oxygen was decreased.
The dissolved ozone concentration of the ozone-containing water before passing through the crushed glass packed column was 5 to 7 mg / liter, and the dissolved ozone concentration of the ozone-containing water after passing through the crushed glass packed column was 3 to 4 mg / liter.
Example 5
The same operation as in Example 4 was repeated except that the supply amount of the mixed gas of ozone and oxygen was further reduced.
The dissolved ozone concentration of the ozone-containing water before passing through the crushed glass packed column was 2-3 mg / liter, and the dissolved ozone concentration of the ozone-containing water after passing through the crushed glass packed column was 1-2 mg / liter.
Example 6
The same operation as in Example 5 was repeated except that the amount of crushed glass was increased to 1,000 g.
The dissolved ozone concentration of ozone-containing water before passing through the crushed glass packed column was 2-3 mg / liter, and the dissolved ozone concentration of ozone-containing water after passing through the crushed glass packed column was 0.3-0.4 mg / liter. .
The results of Examples 1-6 are shown in Table 1.
[0009]
[Table 1]

[0010]
As can be seen in Table 1, by passing ozone-containing water with a high dissolved ozone concentration through a column filled with crushed glass and bringing it into contact with the glass, the dissolved ozone concentration is lowered and the dissolved ozone concentration is 5 times. Since the variation of the measured value is about 1 mg / liter, it is understood that the dissolved ozone concentration of the ozone-containing water can be accurately controlled by the method of the present invention. In addition, from the results of Examples 4 to 6 in which ozone-containing water having a low dissolved ozone concentration was passed, the method of the present invention is also effective for the treatment of ozone-containing wastewater, and when Example 5 and Example 6 are compared, It can be seen that the amount of dissolved ozone decomposed in the treated water can be effectively increased by increasing the amount of crushed glass packed in the column.
[0011]
【The invention's effect】
According to the method of the present invention, high-concentration ozone-containing water can be produced, dissolved ozone can be decomposed by a very simple treatment, and accurately and stably adjusted to ozone-containing water having a desired concentration. Further, in the treatment of ozone-containing wastewater, it is possible to reduce the dissolved ozone concentration using a maintenance-free device.
[Brief description of the drawings]
FIG. 1 is a process flow diagram of one embodiment of the method of the present invention.
[Explanation of symbols]
1 Ultrapure water tank 2 Pump 3 Ejector 4 Ozone generator 5 Water flow pipe 6 Use point 7 Broken glass packed column 8 Sampling point 9 Sampling point

Claims (2)

Pack the crushed glass to be used into the crushed glass packed column to be used, change the amount of crushed glass and the particle size of the crushed glass, and use ozone-containing water with the concentration to be used at the water flow rate to be used. Pass the water, measure the ozone concentration of the ozone-containing water after passing through the crushed glass packed column, and the ozone concentration of the ozone-containing water after passing through the crushed glass packed column becomes the desired reduced ozone concentration. in the particle size of the loading and crushing the glass, the water containing ozone at a concentration of scheduled use in contact with the crushed glass packed column, the ozone of the ozone-containing water, wherein to Rukoto and ozone-containing water having a desired reduced ozone concentration How to adjust the density. Ultrapure water is sent from the ultrapure water tank to the ejector at a flow rate that is planned to be used by the pump. At the same time, a mixed gas of ozone and oxygen is blown into the ejector after changing the supply amount of the mixed gas, and passes through the crushed glass packed column By measuring the ozone concentration of the previous ozone-containing water and blowing it into the ejector with the supply amount of the mixed gas when the ozone concentration is scheduled to be used, the ozone-containing water whose ozone concentration is scheduled to be used is crushed glass packed column The method for adjusting the ozone concentration of ozone-containing water according to claim 1, wherein water is passed through the water.

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