JP3867944B2 - Pure water production method and ultrapure water production apparatus with reduced oxidizing substances - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing pure water such as ultrapure water used for cleaning silicon wafers and the like, and more particularly to a method for producing pure water with a reduced concentration of an oxidizing substance such as hydrogen peroxide. Furthermore, the present invention relates to an apparatus for producing ultrapure water in which the concentration of an oxidizing substance such as hydrogen peroxide is reduced.
[0002]
[Prior art]
In the semiconductor manufacturing industry, ultrapure water from which impurities are highly removed is an essential item. In general, ultrapure water is obtained by removing raw water (for example, river water, groundwater, industrial water) from which large debris has been removed in a pretreatment process using a primary pure water production apparatus and a secondary pure water production apparatus (subsystem). It is manufactured by sequentially processing and supplied to a use point for performing wafer cleaning. Such ultrapure water has such a purity that it is difficult to quantify impurities, but it does not contain any impurities.
[0003]
For example, dissolved oxygen (DO) contained in ultrapure water forms a natural oxide film on the surface of a silicon wafer. When a natural oxide film is formed on the surface of a silicon wafer, growth of an epitaxial Si thin film at a low temperature is hindered, and precise control of the film thickness and film quality of a very thin gate oxide film is hindered. Or, it may increase the contact resistance of the contact hole having a small cross-sectional area. Therefore, it is necessary to suppress the formation of the natural oxide film as much as possible.
Therefore, in the ultrapure water production apparatus, in particular, a degassing apparatus is provided in the primary pure water production apparatus to reduce the dissolved oxygen value (DO value). With this deaeration device, the dissolved oxygen value at the inlet of the secondary pure water production device (subsystem) is usually reduced to about 1 ppbDO (μg / liter).
[0004]
[Problems to be Solved by the Invention]
However, in the ultraviolet oxidation apparatus in the secondary pure water production apparatus, an oxidizing substance such as hydrogen peroxide generated or added in the water is generated in a subsequent process (polish process) in the secondary pure water production apparatus. It has been found to be decomposed to produce oxygen and to increase the dissolved oxygen level in ultrapure water.
[0005]
Then, a method for removing dissolved oxygen caused by hydrogen peroxide generated or added in an ultraviolet oxidizer, which causes the dissolved oxygen value in ultrapure water to be increased, using a membrane deaerator has been proposed. (Japanese Patent Laid-Open No. 9-29251). However, even with ultrapure water from which dissolved oxygen has been removed by this method, there is a problem that the formation of a natural oxide film cannot be suppressed.
[0006]
Apart from this, a method has also been proposed in which hydrogen peroxide remaining in ultrapure water is adsorbed and removed using a synthetic carbon-based granular adsorbent (Japanese Patent Laid-Open No. 9-29233). According to this method, since the hydrogen peroxide itself remaining in the ultrapure water is removed, the formation of a natural oxide film can be suppressed.
However, the method using the above synthetic carbon-based particulate adsorbent requires a large adsorption tower filled with a large amount of adsorbent in order to obtain a predetermined removal rate. There is a problem that the eluate dissolves in ultrapure water, and the life of the adsorbent is as short as several months, and the adsorbent needs to be replaced frequently.
[0007]
In addition, a method for decomposing hydrogen peroxide remaining in ultrapure water by using a catalyst resin supporting palladium has been proposed (Japanese Patent Laid-Open No. 9-192658). However, the palladium-supported catalyst resin has a problem that palladium is physically supported on the resin and may be eluted as colloid or oxide in pure water. There is also a problem that the surface of palladium supported on the resin is contaminated with an organic substance or the like, and the capacity is lowered.
[0008]
Therefore, an object of the present invention is a method for producing pure water from which an oxidizing substance such as hydrogen peroxide that is generated or added to pure water and causes a natural oxide film is removed, It is an object of the present invention to provide a method in which there is no problem that there is no or a problem of contamination, and the frequency is low even when replacement is necessary.
Furthermore, an object of the present invention is an ultrapure water production apparatus, which can remove an oxidizing substance such as hydrogen peroxide that causes a natural oxide film, and an eluate is mixed into pure water from the oxidizing substance removing apparatus. It is an object of the present invention to provide an ultrapure water production apparatus in which there is no problem or a small problem and the lifetime of an oxidizing substance removing apparatus is long.
[0009]
In order to achieve the object of the present invention, the present inventors have studied various methods for removing oxidizing substances such as hydrogen peroxide contained in pure water. As a result, by bringing the metal ion cation exchange resin into contact with pure water containing an oxidizing substance, the content of the oxidizing substance can be reduced, and the above effect can be achieved with a relatively small amount of the metal ion positive cation. The present invention has been achieved by finding that it can be achieved with an ion exchange resin and that the lifetime of the metal ion type cation exchange resin is long.
[0010]
[Means for Solving the Problems]
The present invention relates to pure water with reduced oxidizing substance content, characterized in that a metal ion cation exchange resin is brought into contact with pure water containing an oxidizing substance , and the oxidizing substance is hydrogen peroxide. The present invention relates to a method for producing water. Furthermore, the present invention comprises an ultraviolet oxidation device, a metal ion type cation exchange resin filling device, and a desalination device, and is installed so that primary pure water is passed in this order , and the primary pure water is irradiated with ultraviolet rays. The present invention relates to an ultrapure water production apparatus used for producing pure water with a reduced hydrogen peroxide content , characterized in that a metal ion type cation exchange resin is brought into contact with water containing hydrogen peroxide oxidized .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The method of manufacturing a pure water of the present invention, the oxidizing substance to be removed is a hydrogen peroxide, other oxidizing substances, for example, that ozone is also removed can. The pure water containing the oxidizing substance may be water that is oxidized by irradiating the primary pure water with ultraviolet rays in an ultrapure water production apparatus. This water contains a relatively large amount of hydrogen peroxide by ultraviolet irradiation. However, the pure water containing the oxidizing substance is not limited to this. For example, for the purpose of sterilizing the piping system or converting nonionic silica into ionic silica, For example, in a pure water apparatus having a structure to which ozone is added, hydrogen peroxide generated by decomposition of the added ozone can also be mentioned.
[0012]
As a metal ion used for the metal ion type cation exchange resin used for this invention, the ion of the metal which has a valence more than bivalence can be mentioned, for example. Examples of such metal ions include iron ions, copper ions, nickel ions, chromium ions, cobalt ions, and the like. Although there is no restriction | limiting in particular in the cation exchange resin used as a base material, From a viewpoint that the retention power of a metal ion is high, it is suitable that it is a strongly acidic cation exchange resin. Further, from the viewpoint that it is difficult to be decomposed by metal ions, a highly crosslinked cation exchange resin is appropriate. The amount of metal ions retained with respect to the cation exchange resin is appropriately determined in consideration of the ability to decompose an oxidizing substance required for the metal ion type cation exchange resin and the stability of the cation exchange resin.
The metal ion cation exchange resin can be prepared by bringing a hydrogen ion cation exchange resin into contact with an aqueous solution containing metal ions. The amount of metal ions retained relative to the cation exchange resin can be changed by adjusting the concentration and contact time of the aqueous solution containing the metal ions.
[0013]
The contact between the pure water containing the oxidizing substance and the metal ion type cation exchange resin can be performed, for example, by passing pure water through a tower packed with the metal ion type cation exchange resin. Further, the contact time between pure water and the metal ion cation exchange resin can be appropriately determined in consideration of the concentration of the oxidizing substance contained in the pure water, the ability of the metal ion cation exchange resin, and the like.
The oxidizing substance that has come into contact with the metal ion type cation exchange resin is decomposed to finally become oxygen and water. Oxygen generated by the decomposition can be easily removed by installing a deaeration means such as a vacuum deaeration device, a membrane deaeration device, a palladium resin device, or a nitrogen aeration device.
[0014]
In the method of the present invention, pure water brought into contact with a metal ion type cation exchange resin, hydrogen ion type strongly acidic cation exchange resin alone, hydroxide ion type strongly basic anion exchange resin alone, or hydrogen Mixed bed of ion-type strongly acidic cation exchange resin and hydroxide ion-type strongly basic anion exchange resin, or hydrogen ion-type strongly acidic cation exchange resin and hydroxide ion-type strongly basic anion exchange resin It is effective to contact the laminated resin layer. By making it contact with a hydrogen ion type strong acidic cation exchange resin, the metal ion eluted in a trace amount from a metal ion type cation exchange resin can be removed. By contacting with a hydroxide ion type strongly basic anion exchange resin, even if metal ion type cation exchange resin is oxidized and decomposed by contact with hydrogen peroxide and a small amount of anionic organic substances are released, it can be removed. . Moreover, the same effect is acquired also by mixing a hydrogen ion type strong acidic cation exchange resin and / or a hydroxide ion type strong basic anion exchange resin with a metal ion type cation exchange resin.
[0015]
The ultrapure water production apparatus of the present invention comprises an ultraviolet oxidation apparatus, a metal ion type cation exchange resin filling apparatus, and a desalting apparatus, and is characterized in that it is installed so as to pass primary pure water in this order.
Hydrogen peroxide generated by the ultraviolet oxidation apparatus is not sufficiently decomposed by the cartridge polisher in the subsequent stage, and remains in the outlet water of the cartridge polisher with little decomposition with time. However, in the apparatus of the present invention, ultrapure water having an extremely low hydrogen peroxide concentration is obtained by decomposing hydrogen peroxide with a metal ion type cation exchange resin filling apparatus which is an oxidizing substance decomposing apparatus installed in the preceding stage of the cartridge polisher. Can be obtained. Furthermore, dissolved oxygen generated by the decomposition of hydrogen peroxide is removed by a deaeration device. Therefore, in the apparatus of the present invention, ultrapure water having both extremely low hydrogen peroxide concentration and dissolved oxygen concentration can be obtained, and the formation of a natural oxide film on the silicon wafer can be suppressed.
[0016]
In the present invention, primary pure water is pure water obtained by treating raw water with a primary pure water system that is usually used. In order to obtain primary pure water, for example, in the apparatus shown in FIG. 3, first, raw water such as industrial water is passed through the pretreatment system 4 to remove suspended substances and a part of organic matter in the raw water. The desalination apparatus 12 that supplies the primary pure water system 8 through the filtered water tank 6 and removes the impurity ions in the water, and the reverse osmosis membrane apparatus that removes inorganic ions, organic substances, fine particles, and the like in the water. 16. Water is sequentially passed through a vacuum deaerator 20 that removes dissolved gas such as dissolved oxygen in water, and a regenerative mixed-bed desalinator 22 that produces high-purity pure water by removing remaining ions and the like. Primary pure water can be obtained.
[0017]
In the present invention, the ultraviolet oxidizer may be any apparatus that includes an ultraviolet lamp capable of irradiating the water to be treated with ultraviolet rays and can decompose organic substances in the water to be treated. Examples of the ultraviolet rays include ultraviolet rays having a wavelength near 185 nm. Further, in addition to ultraviolet light having a wavelength near 185 nm, ultraviolet light having a wavelength near 254 nm may be used. However, ultraviolet light having a wavelength of about 254 nm has a lower ability to decompose organic substances than ultraviolet light having a wavelength of about 185 nm. There is an ultraviolet irradiation device that irradiates a wavelength near 254 nm but hardly irradiates a wavelength near 185 nm. In the present invention, it is preferable to use an ultraviolet oxidizer capable of strongly irradiating ultraviolet rays having a wavelength of around 185 nm and ultraviolet rays having a wavelength of around 254 nm, from the viewpoint of satisfactorily decomposing organic matter. The ultraviolet lamp to be used is not particularly limited, but a low-pressure mercury lamp is preferable. In addition, examples of the ultraviolet oxidation apparatus include a distribution type and an immersion type, and among these, the distribution type is preferable from the viewpoint of processing efficiency.
[0018]
In the present invention, the oxidizing substance decomposing apparatus is an apparatus filled with a metal ion type cation exchange resin as a substance for decomposing an oxidizing substance. The metal ion type cation exchange resin is the same as that described above.
[0019]
In the present invention, the degassing apparatus is not particularly limited as long as it is an apparatus capable of removing oxygen generated by decomposition of hydrogen peroxide. For example, the water to be treated is allowed to flow into one chamber partitioned by a gas separation membrane, and the other chamber is depressurized so that the gas contained in the water to be treated is transferred to the other chamber through the gas separation membrane and removed. Mention may be made of a membrane deaerator. As the gas separation membrane, a membrane in which a hydrophobic polymer membrane such as tetrafluoroethylene or silicone rubber is formed into an appropriate shape such as a hollow fiber membrane is usually used. In addition to the membrane deaerator, a degassing gas apparatus such as a vacuum degassing tower or a heated degassing apparatus can also be used. However, the membrane-type degassing device as a degassing device has an advantage that impurities are not mixed into the water from the device, impurities are not eluted into the water from the filling of the device, and the device is small. .
[0020]
In the present invention, for example, an ion exchange apparatus can be used as the desalting apparatus. The ion exchange device is preferably a non-regenerative ion exchange device. Non-regenerative ion exchange devices include, for example, an ion exchange device using a mixed bed of a strongly acidic cation exchange resin and a strongly basic anion exchange resin (one mixed bed type), or a simple basic anion exchange resin. Ion-exchange equipment with a single bed (single-bed type), single-bed layer of strong basic anion exchange resin on the inlet side, mixed bed layer of strongly acidic cation exchange resin and strong basic anion exchange resin on the outlet side A multi-layered ion exchange device (single-layered single-column system) installed in the front, and a resin tower with a single bed of strongly basic anion exchange resin on the front side, a strongly acidic cation exchange resin and a strongly basic anion exchange resin An ion exchange apparatus (two-column type) in which a resin tower with a mixed bed is provided on the rear stage side. Among these, when a mixed bed single tower type ion exchange apparatus is used, since there is no change of pH of water in any position in a mixed bed layer, there exists an advantage that efficient ion exchange can be performed.
[0021]
Next, the procedure for producing ultrapure water using the ultrapure water production apparatus of the present invention will be described with reference to FIG. FIG. 1 is a system diagram showing an ultrapure water production apparatus according to an embodiment of the present invention . For example, primary pure water obtained by various pretreatment processes, for example, with a TOC concentration of 2 ppb or less is supplied to the pure water storage tank 24 of the secondary system 10. The resistivity of primary pure water stored in the pure water storage tank 24 is usually 10 MΩ · cm or more. The pure water exiting the pure water storage tank 24 is processed by the ultraviolet oxidizer 26. The ultraviolet oxidizer 26 is an ultraviolet oxidizer equipped with a low-pressure mercury lamp capable of strongly irradiating ultraviolet rays in the vicinity of 185 nm, which has a high ability to separate organic substances, and is installed to decompose organic substances in water into carbonic acid and organic acids. . When the dissolved oxygen concentration before and after the ultraviolet oxidizer 26 is measured, a phenomenon is observed in which the dissolved oxygen concentration changes drastically from 22 ppb to 6 ppb. In this phenomenon, dissolved oxygen in the water to be treated by the ultraviolet oxidizer 26 is consumed as an oxygen source for the oxidation of organic matter, or is consumed by the generation of radicals, ozone, hydrogen peroxide, and the like due to the interaction between ultraviolet rays and water. It is thought to be. Therefore, the hydrogen peroxide concentration before and after the ultraviolet oxidizer 26 increases from several ppb to 50 ppb.
[0022]
Next, the water treated by the ultraviolet oxidation device 26 is passed through a metal ion cation exchange resin filling device 27 which is an oxidative substance decomposition device, and is brought into contact with the ion exchange resin filled in the device. Decomposes hydrogen peroxide in treated water. In this case, the contact of the water to be treated with the metal ion type cation exchange resin is preferably carried out by a fixed bed method in view of the removal efficiency of hydrogen peroxide. When the water to be treated is brought into contact with the ion exchange resin in such a fixed bed system, the water flow condition is preferably set to a linear flow velocity of 50 m / h to 600 m / h, particularly 100 to 300 m / h. If the linear flow rate exceeds 600 m / h, hydrogen peroxide may not be sufficiently removed.
[0023]
Next, the water treated by the metal ion type cation exchange resin filling device 27 is passed through the membrane deaerator 50, the dissolved oxygen in the treated water is preferably 1 ppb or less, and the total dissolved gas concentration is preferably 3000 ppb. Reduce to:
[0024]
Next, the treated water is passed through a cartridge polisher 28 which is a non-regenerative ion exchange device, and primary water containing elution ions generated from the metal ion type cation exchange resin filling device 27 and the membrane type deaeration device 50 is contained. Further remove ions in pure water. In this way, the treated water is passed in the order of the metal ion cation exchange resin filling device 27 → the membrane deaeration device 50 → the cartridge polisher 28, so that the metal ion cation exchange resin filling device 27 and the membrane desorption are supplied. Elution ions from the gas device 50 can be effectively removed.
[0025]
Further, the ultrafiltration membrane separation device 30 removes residual fine particles and the like in the water to produce ultrapure water, and this ultrapure water is supplied to the use place 32. The ultrapure water returns to the pure water storage tank 24 through the secondary pure water circulation pipe 34 in both cases of using and not using the pure water storage tank 24 → ultraviolet oxidizer 26 → metal ion. A closed loop consisting of a cation exchange resin filling device 27 → a membrane deaeration device 50 → a cartridge polisher 28 → an ultrafiltration membrane separation device 30 → a pure water storage tank 24 is constantly circulated.
[0026]
Further, in the present invention, as shown in FIG. 2, the water near the 254 nm is irradiated before the outlet water of the ultraviolet oxidizer 26 is passed through the metal ion cation exchange resin filling device 27. It is preferable to pass water through an ultraviolet sterilizer 25 that irradiates almost no wavelength near 185 nm. In FIG. 2, the same components as those in FIG. Since the ultraviolet sterilizer 25 can be expected to decompose hydrogen peroxide, the load of the metal ion cation exchange resin in the subsequent stage can be reduced, and the use period can be extended or the filling amount can be reduced.
[0027]
In addition, the ultrapure water production apparatus of the present invention is also a method for continuously injecting ozone into an appropriate portion of the circulation line of the ultrapure water production and supply system to control the number of bacteria in the ultrapure water to the lowest level. Applicable. In other words, if the removal of hydrogen peroxide generated by the ozone injection and the decomposition action of the ultraviolet oxidizer is performed by the metal ion cation exchange resin filling device and the deaeration device in the subsequent stage, the function of the ultrapure water production device is enhanced. Can do.
[0028]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
Example 1
Iron ion type strong acid cation exchange resin 1 (W / W)% FeSO ₄ .7H ₂ O aqueous solution (Fe (0.2 (W / W) as Fe) in 100 ml of hydrogen ion type strong acid cation exchange resin %) Was added and stirred for 1 hour. Subsequently, the ion exchange resin was washed with water by decantation to obtain an iron ion type strongly acidic cation exchange resin.
Pure water containing 100 ppb hydrogen peroxide was passed through a column packed with these iron ion type strongly acidic cation exchange resins (5 g Fe / liter-CER) under SV50 conditions, and the decomposition rate of hydrogen peroxide in the effluent water Was measured by the phenolphthalin method. The results are shown in FIG.
It can be seen that as the iron ion retention amount increases, the decomposition rate of hydrogen peroxide increases and hydrogen peroxide is decomposed by the iron ion type strongly acidic cation exchange resin.
Similar results were obtained with a copper ion type strongly acidic cation exchange resin prepared by replacing the FeSO ₄ · 7H ₂ O aqueous solution with the CuCl ₂ · 5H ₂ O aqueous solution.
[0029]
Example 2
Pure water containing 100 ppb hydrogen peroxide was passed through a column packed with an iron ion type strongly acidic cation exchange resin (10 g Fe / liter-CER) under SV50 conditions. The decomposition rate was measured by the phenol phthaline method. The results are shown in FIG. From the results of FIG. 5, it can be seen that there was no change in the performance of the iron ion type strongly acidic cation exchange resin used within the measurement period.
For comparison, the same experiment was performed using an amber sorb. As a result, it can be seen that the hydrogen peroxide concentration in the effluent increases from the time when the hydrogen peroxide flow rate exceeds 700 mgH ₂ O ₂ / liter-CER, and there is a problem in the life. Also, the hydrogen peroxide removal efficiency is superior to the comparison using Ambersorb, and it can be seen that the hydrogen peroxide removal efficiency is almost eliminated.
[0030]
Example 3
Primary pure water (dissolved oxygen 40 ppb, resistivity 17.5 MΩ · cm) is treated according to the equipment shown in FIG. 1 and the following equipment specifications to produce ultrapure water for 6 months, and the amount of hydrogen peroxide in the ultrapure water. And the change with time of the amount of dissolved oxygen was examined. The measurement points of the test water are the outlet of the UV oxidizer and the place (use point) where ultra pure water is used. In addition, hydrogen peroxide was quantified by the method described above. The measurement results at the use location (use point) of ultrapure water showed almost no change over 6 months, with hydrogen peroxide amount of 1 ppb or less and dissolved oxygen amount of 1 ppb or less. Also, the measured values at the outlet of the ultraviolet oxidizer were hardly changed over the course of 6 months, with the hydrogen peroxide amount being 50 ppb and the dissolved oxygen amount being 10 ppb.
[0031]
(Specifications of each device)
Ultraviolet oxidizer: Low pressure TDFL-4 (manufactured by Chiyoda Corporation) Ultraviolet radiation dose 0.3kW · h / m ³
Oxidizing substance decomposition apparatus; cylindrical packed tower (height 90 cm, inner diameter 30 cm) packed with copper ion type strongly acidic cation exchange resin prepared in the same manner as in Example 1, SV 150 h ⁻¹
Membrane type deaerator; MJ-520p (manufactured by Dainippon Ink & Chemicals) 18 degree vacuum
Cartridge polisher: Mixed bed type ion exchange apparatus, SV70-80h ^-1 mixed and filled with cation exchange resin and anion exchange resin
Ultrafiltration membrane separator; FIT-3016 (Asahi Kasei Kogyo Co., Ltd.)
[0032]
【The invention's effect】
According to the manufacturing method of the present invention, pure water from which an oxidizing substance such as hydrogen peroxide, which is generated or added in pure water and causes a natural oxide film, is removed is mixed with eluate in pure water. It can manufacture while suppressing. Further, the metal ion type strongly acidic cation exchange resin to be used has an advantage that it has a long life, a high removal rate, and is very advantageous in practice.
Furthermore, when the apparatus for producing ultrapure water of the present invention is used, ultrapure water having extremely low hydrogen peroxide concentration and dissolved oxygen concentration can be obtained, and the formation of a natural oxide film on the silicon wafer can be suppressed.
[Brief description of the drawings]
FIG. 1 is a flowchart showing an embodiment of an ultrapure water production apparatus of the present invention.
FIG. 2 is a flowchart showing another embodiment of the ultrapure water production apparatus of the present invention.
FIG. 3 is a flowchart showing an example of a conventional ultrapure water production apparatus.
FIG. 4 shows the relationship between the iron ion retention amount of the iron ion type strongly acidic cation exchange resin and the decomposition rate of hydrogen peroxide in the effluent water.
FIG. 5 shows the results of a performance comparison test between an iron ion type strongly acidic cation exchange resin and ambersorb.
[Explanation of symbols]
2 Raw water storage tank 4 Pretreatment system 6 Filtration water tank 8 Primary pure water system 10 Secondary pure water system 12 Desalination device 16 Reverse osmosis membrane device 20 Vacuum deaeration device 22 Regenerative mixed bed desalination device 24 Pure water storage tank 25 UV sterilization Equipment 26 Ultraviolet oxidation equipment 27 Metal ion type strongly acidic cation exchange resin filling equipment 28 Cartridge polisher 30 Ultrafiltration membrane separation equipment 32 Use point (use point)
34 Secondary pure water circulation piping 50 Membrane type deaerator

Claims (6)

A method for producing pure water with reduced oxidizing substance content , wherein a metal ion type cation exchange resin is brought into contact with pure water containing an oxidizing substance , and the oxidizing substance is hydrogen peroxide .   The production method according to claim 1, wherein the pure water containing an oxidizing substance is water obtained by oxidizing primary pure water by irradiating with ultraviolet rays. The production method according to claim 1 or 2 , wherein the metal ion of the metal ion type cation exchange resin has a valence of 2 or more.   The manufacturing method of any one of Claims 1-3 which deaerate-process the pure water made to contact metal ion type cation exchange resin. It consists of an ultraviolet oxidation device, a metal ion type cation exchange resin filling device, and a desalination device.The primary pure water was installed in this order , and the primary pure water was irradiated with ultraviolet rays and oxidized. An ultrapure water production apparatus used for producing pure water with reduced hydrogen peroxide content , wherein a metal ion type cation exchange resin is brought into contact with water containing hydrogen oxide . The apparatus of Claim 5 which provided the deaeration apparatus between the metal ion type cation exchange resin filling apparatus and the desalination apparatus.

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