Hydrogen peroxide removal method, hydrogen peroxide removal device, and pure water production device

Abstract

To provide a hydrogen peroxide removing device that can treat hydrogen peroxide in a wide range of concentrations in the to-be-treated water, in a fast and stable manner for a long time.SOLUTION: A hydrogen peroxide removing device has a hydrogen peroxide removal chamber 23 that is provided between an anode 11 and a cathode 12 and is filled with an ion exchanger having a hydrogen peroxide-decomposable metal catalyst supported thereon, and a cation exchange film 33 and an anion exchange film 81 disposed between the hydrogen peroxide removal chamber 23 and the cathode 12. The cation exchange film 33 and anion exchange film 81 are placed on each other so that the cation exchange film 33 is on the cathode 12 side and the anion exchange film 81 is on the hydrogen peroxide removal chamber 23 side. While DC voltage is applied between the anode 11 and the cathode 12, the to-be-treated water is flowed to the hydrogen peroxide removal chamber 23.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method and apparatus for removing hydrogen peroxide from water in wastewater treatment and pure water / ultrapure water production processes, and to a pure water production apparatus. [Background technology]

[0002] Conventionally, hydrogen peroxide is widely used as an oxidizing agent together with chemicals such as acids and alkalis in cleaning and surface treatment of electronic components. Because hydrogen peroxide has oxidizing power, it is necessary to properly manage and remove hydrogen peroxide so that it does not flow into equipment with low oxidation resistance, such as ion exchange resin equipment that constitutes a water treatment system. In general, deterioration caused by oxidizing agents causes irreparable and fatal damage to water treatment equipment. In particular, it is known that ion exchange resins in electrodeionization (EDI) devices are easily deteriorated in the presence of oxidizing agents. For example, it is known that when hydrogen peroxide is contained in the water to be treated in an ultrapure water production system, part of the ion exchange resins in the ultrapure water production system are oxidized and decomposed, causing the elution of organic matter.

[0003] In addition, hydrogen peroxide has a strong sterilizing power due to its oxidizing power, so when wastewater containing hydrogen peroxide is discharged from a pure water system to an external wastewater system, it is necessary to remove the hydrogen peroxide before discharging it, since it may affect the biological treatment equipment included in the wastewater treatment system. In addition, pure water and ultrapure water production systems sometimes use ultraviolet oxidation equipment to break down total organic carbon (TOC) components, and it is known that the treated water after ultraviolet oxidation contains trace amounts of hydrogen peroxide.

[0004] Conventionally, methods for reducing hydrogen peroxide in water to be treated include adding a reducing agent, contacting the water with activated carbon, and contacting the water with a resin carrying a metal. In the method of adding a reducing agent, a reducing agent such as sodium sulfite, sodium hydrogen sulfite, or sodium thiosulfate is added to the water to be treated that contains hydrogen peroxide. Since the reaction rate between the reducing agent and hydrogen peroxide is very high, this method can reliably decompose and remove hydrogen peroxide. However, it is difficult to control the amount of reducing agent added, and in order to reliably remove hydrogen peroxide, an excessive amount of reducing agent must be added, and the reducing agent increases the amount of ions in the liquid, which may lead to deterioration of water quality.

[0005] In the method of contacting with activated carbon, the water to be treated is usually passed through a packed tower of activated carbon, but the reaction rate is slow, so the space velocity of the water passing through cannot be increased, and this causes problems such as the need for a large-sized device. In addition, there is a concern that activated carbon itself may be oxidized as hydrogen peroxide decomposes, causing the particles to collapse.

[0006] As a method of contacting with a resin carrying a metal, for example, a method has been proposed in which the water to be treated containing hydrogen peroxide is brought into contact with a catalytic resin in which a palladium or platinum catalyst is carried on an ion exchange resin (Patent Document 1). In this method, hydrogen peroxide is decomposed by the reaction shown in the following formula. 2H2O2 → 2H2O+O2 [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2007-185587 A Summary of the Invention [Problem to be solved by the invention]

[0008] Although the method of decomposing and removing hydrogen peroxide using a catalytic resin in which a catalyst made of palladium, platinum, or the like is supported on an ion exchange resin has a high decomposition rate of hydrogen peroxide compared to the method of contacting with activated carbon, it is desired to further improve the decomposition rate.In addition, it is known that the decomposition rate of hydrogen peroxide decreases with time in the method using a catalytic resin, and it is desired to be able to decompose hydrogen peroxide stably for a long period of time.

[0009] The present invention aims to provide a hydrogen peroxide removal method and device that can rapidly and stably treat hydrogen peroxide in a wide range of concentrations in water to be treated for a long period of time, as well as a pure water production system equipped with said device. Another object of the present invention is to provide a hydrogen peroxide removal method and device that can also be applied to wastewater treatment. [Means for solving the problem]

[0010] The hydrogen peroxide removal method of the present invention is a method for removing hydrogen peroxide contained in water to be treated, and includes a step of passing the water to be treated through a hydrogen peroxide removal chamber that is provided between an anode and a cathode and filled with an ion exchanger while applying a DC voltage between the anode and the cathode, at least a part of the ion exchanger filled in the hydrogen peroxide removal chamber is an ion exchanger carrying a metal catalyst having hydrogen peroxide decomposition ability, and a first cation exchange membrane and a second cation exchange membrane are overlapped and arranged between at least one hydrogen peroxide removal chamber and the cathode so that the first cation exchange membrane is on the cathode side and the first anion exchange membrane is on the at least one hydrogen peroxide removal chamber side.

[0011] The hydrogen peroxide removal apparatus of the present invention is a hydrogen peroxide removal apparatus for removing hydrogen peroxide contained in water to be treated, and comprises an anode and a cathode, a hydrogen peroxide removal chamber provided between the anode and the cathode and filled with an ion exchanger, and a first cation exchange membrane and a first anion exchange membrane arranged between at least one of the hydrogen peroxide removal chambers and the cathode, at least a portion of the ion exchanger filled in the hydrogen peroxide removal chamber is an ion exchanger carrying a metal catalyst having hydrogen peroxide decomposition ability, the first cation exchange membrane and the first anion exchange membrane are arranged by being superimposed on each other so that the first cation exchange membrane is on the cathode side and the first anion exchange membrane is on the side of at least one of the hydrogen peroxide removal chambers, and a DC voltage is applied between the anode and the cathode.

[0012] The pure water production system of the present invention comprises a hydrogen peroxide removal device based on the present invention, and an ultraviolet oxidation device provided upstream of the hydrogen peroxide removal device.

[0013] In the present invention, an ion exchanger carrying a metal catalyst having hydrogen peroxide decomposition ability is filled in the hydrogen peroxide removal chamber arranged between the anode and the cathode, and a DC voltage is applied between the anode and the cathode while the water to be treated is passed through the hydrogen peroxide removal chamber. With this configuration, according to the present invention, the decomposition of hydrogen peroxide and the electrical regeneration of the ion exchanger proceed in parallel, and the hydrogen peroxide decomposition and removal performance can be maintained at a stable high level for a long period of time. Furthermore, in the present invention, a first cation exchange membrane and a first anion exchange membrane are stacked on top of each other between the hydrogen peroxide removal chamber and the cathode, with the first cation exchange membrane facing the cathode and the first anion exchange membrane facing the hydrogen peroxide removal chamber. When a DC voltage is applied between the anode and the cathode, a water dissociation reaction proceeds at the interface between the first cation exchange membrane and the first anion exchange membrane, and hydroxide ions (OH -) is supplied from the first anion exchange membrane to the hydrogen peroxide removal chamber. As a result, the electrical resistance between the anode and the cathode is reduced, making it possible to pass a large current through the hydrogen peroxide removal chamber at a low voltage, and promoting the regeneration of the ion exchanger in the hydrogen peroxide removal chamber. In the present invention, when the first cation exchange membrane and the first anion exchange membrane are superimposed, they may be simply superimposed on each other, or a catalyst that promotes the water dissociation reaction may be disposed at the interface between them to form a bipolar membrane.

[0014] In the present invention, examples of the metal catalyst having hydrogen peroxide decomposition ability include platinum group metal catalysts such as palladium and platinum, as well as iron, manganese, nickel, gold, silver, copper, chromium, aluminum, and compounds thereof. Among them, platinum group metal catalysts are more preferably used because they have high catalytic activity for hydrogen peroxide decomposition. The platinum group metal catalyst is a catalyst containing one or more metals selected from ruthenium, rhodium, palladium, osmium, iridium, and platinum. The platinum group metal catalyst may contain any one of these metal elements alone or may be a combination of two or more of these. Among them, platinum, palladium, and platinum / palladium alloys have high catalytic activity and are preferably used as platinum group metal catalysts.

[0015] The present invention is more advantageous when removing hydrogen peroxide from water to be treated that contains carbonic acid components that are a load on the anion exchanger, by using an anion exchanger carrying a platinum group metal catalyst as the metal catalyst. When the hydrogen peroxide removal chamber is partitioned by an anion exchange membrane on the anode side, the anion components, i.e., carbonic acid components, adsorbed from the water to be treated to the anion exchanger in the hydrogen peroxide removal chamber are desorbed from the anion exchanger by electrical regeneration and discharged in the form of anions from the hydrogen peroxide removal chamber through the anion exchange membrane on the anode side. In other words, the present invention not only produces treated water from which hydrogen peroxide has been removed, but also improves the quality of the treated water.

[0016] In addition, in the present invention, the regeneration state of the ion exchanger carrying the platinum group metal catalyst can be maintained by continuously applying a DC voltage. -1 It is also possible to set the SV to the above and operate the system. The space velocity SV is a unit that indicates how many times the volume of the ion exchanger carrying the platinum group metal catalyst packed in the hydrogen peroxide removal chamber is being treated per unit time. Specifically, the SV value can be calculated by dividing the flow rate (L / h) of the water to be treated by the volume (L) of the ion exchanger carrying the platinum group metal catalyst. Being able to operate at an SV value two or three times higher than normal is advantageous because it makes it possible to reduce the amount of catalyst, which is expensive because it carries a precious metal, by half or one third to treat the same amount of water to be treated.

[0017] In the hydrogen peroxide removal device of the present invention, a desalting chamber filled with an ion exchanger may be provided adjacent to the cathode side or anode side of the hydrogen peroxide removal chamber via an intermediate ion exchange membrane, and treated water treated by the hydrogen peroxide removal chamber may be passed through the desalting chamber. The intermediate ion exchange membrane may be a first cation exchange membrane and a first anion exchange membrane superposed on each other, or a second anion exchange membrane independent of the first cation exchange membrane and the first anion exchange membrane superposed on each other. By configuring in this way, it is possible to simultaneously remove hydrogen peroxide from the water to be treated and desalt the water to be treated. By using the treated water discharged from the desalting chamber, it is possible to produce high-purity pure water and ultrapure water. Effect of the Invention

[0018] According to the present invention, it is possible to stably remove hydrogen peroxide from water to be treated that contains a wide range of hydrogen peroxide concentrations over a long period of time. As a result, it is possible to stably operate, for example, the entire water treatment facility to which water to be treated that contains hydrogen peroxide is supplied. [Brief description of the drawings]

[0019] [Figure 1]1 is a schematic diagram showing a hydrogen peroxide removal device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing a specific example of a hydrogen peroxide removal device. [Diagram 3] FIG. 3 is a schematic diagram illustrating the operation of the hydrogen peroxide removal device shown in FIG. 2. [Figure 4] 3 is a schematic diagram showing an example of the flow of water in the hydrogen peroxide removal device shown in FIG. 2. [Diagram 5] FIG. 2 is a schematic diagram showing another specific example of a hydrogen peroxide removal device. [Figure 6] FIG. 2 is a schematic diagram showing another specific example of a hydrogen peroxide removal device. [Figure 7] FIG. 7 is a schematic diagram illustrating the operation of the hydrogen peroxide removal device shown in FIG. [Figure 8] FIG. 2 is a schematic diagram showing another specific example of a hydrogen peroxide removal device. [Figure 9] FIG. 9 is a schematic diagram illustrating the operation of the hydrogen peroxide removal device shown in FIG. [Figure 10] FIG. 2 is a schematic diagram showing another specific example of a hydrogen peroxide removal device. [Figure 11] FIG. 11 is a schematic diagram illustrating the operation of the hydrogen peroxide removal device shown in FIG. [Figure 12] FIG. 2 is a schematic diagram showing another specific example of a hydrogen peroxide removal device. [Figure 13] FIG. 4 is a schematic diagram showing a hydrogen peroxide removal device according to a second embodiment of the present invention. [Figure 14] FIG. 2 is a schematic diagram showing another specific example of a hydrogen peroxide removal device. [Figure 15] FIG. 2 is a schematic diagram showing another specific example of a hydrogen peroxide removal device. [Figure 16] FIG. 16 is a schematic diagram illustrating the operation of the hydrogen peroxide removal device shown in FIG. [Figure 17] FIG. 2 is a schematic diagram showing another specific example of a hydrogen peroxide removal device. [Figure 18] FIG. 18 is a schematic diagram illustrating the operation of the hydrogen peroxide removal device shown in FIG. [Figure 19] FIG. 2 is a schematic diagram showing another specific example of a hydrogen peroxide removal device. [Figure 20] FIG. 1 is a schematic diagram showing an example of the configuration of a conventional water purifying apparatus. [Figure 21] 1 is a schematic diagram showing an example of the configuration of a pure water producing apparatus based on the present invention. [Figure 22] FIG. 1 is a schematic diagram showing an example of the configuration of an ultrapure water production apparatus. [Figure 23] FIG. 2 is a schematic diagram showing another example of the configuration of an ultrapure water production apparatus. [Figure 24] FIG. 2 is a schematic diagram showing another example of the configuration of an ultrapure water production apparatus. [Diagram 25] FIG. 2 is a schematic diagram showing another example of the configuration of an ultrapure water production apparatus. [Figure 26] FIG. 2 is a schematic diagram showing a main part of a hydrogen peroxide removal device in Comparative Example 1. [Figure 27] FIG. 4 is a schematic diagram showing a main part of a hydrogen peroxide removal device of Comparative Example 2. [Figure 28] 1 is a graph showing the results of Example 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Next, the present invention will be described with reference to the drawings, with respect to an embodiment of the present invention. However, the present invention is not limited to the embodiment shown in the drawings.

[0021] FIG. 1 shows the configuration of a hydrogen peroxide removal device according to a first embodiment of the present invention. The hydrogen peroxide removal device includes at least one hydrogen peroxide removal chamber 23 between an anode chamber 21 equipped with an anode 11 and a cathode chamber 25 equipped with a cathode 12. The hydrogen peroxide removal chamber 23 is partitioned by an anion exchange membrane 32 located on the anode 11 side and an ion exchange membrane located on the cathode 12 side. An ion exchanger (IER) carrying a platinum group metal catalyst is filled in the hydrogen peroxide removal chamber 23. In the figure, the ion exchanger carrying a platinum group metal catalyst is indicated by "Cat. IER". The ion exchange membrane located on the cathode 12 side is an anion exchange membrane 81 and a cation exchange membrane 33 stacked on top of each other, and is arranged so that the anion exchange membrane 81 faces the hydrogen peroxide removal chamber 23 side and the cation exchange membrane 33 faces the cathode 12 side. 1, an anode 11 and a cathode 12 face each other, and an anode chamber 21, a first concentrating chamber 22, a hydrogen peroxide removal chamber 23, a second concentrating chamber 24, and a cathode chamber 25 are arranged between the anode 11 and the cathode 12 in this order from the anode 11 side. The anode chamber 21 and the first concentrating chamber 22 are separated by a cation exchange membrane 31, and the first concentrating chamber 22 and the hydrogen peroxide removal chamber 23 are separated by an anion exchange membrane 32. The hydrogen peroxide removal chamber 23 and the second concentrating chamber 24 are separated by an anion exchange membrane 81 and a cation exchange membrane 33 superimposed on each other. The second concentrating chamber 24 and the cathode chamber 25 are separated by an anion exchange membrane 34. The anode chamber 21, the first concentration chamber 22, the second concentration chamber 24, and the cathode chamber 25 are each filled with an ion exchanger that does not support a platinum group metal catalyst. Here, as the ion exchanger, either an anion exchanger or a cation exchanger, or both of them are used. When both an anion exchanger and a cation exchanger are used, the ion exchanger may be packed in a mixed bed configuration in which an anion exchanger and a cation exchanger are mixed and packed, or in a multi-layer bed configuration in which they are packed so as to form a layer of an anion exchanger and a layer of a cation exchanger, respectively.

[0022] Next, the operation of the hydrogen peroxide removal device shown in Fig. 1 will be described. When hydrogen peroxide is removed from water to be treated that contains hydrogen peroxide, feed water is passed through anode chamber 21, first concentration chamber 22, second concentration chamber 24, and cathode chamber 25, respectively, and the water to be treated is passed through hydrogen peroxide removal chamber 23 with a DC voltage applied between anode 11 and cathode 12. When the water to be treated that contains hydrogen peroxide is passed through hydrogen peroxide removal chamber 23, the hydrogen peroxide in the water to be treated is decomposed into water and oxygen by a catalytic reaction with the platinum group metal catalyst supported on the ion exchanger in hydrogen peroxide removal chamber 23, and as a result, treated water from which hydrogen peroxide has been removed flows out of hydrogen peroxide removal chamber 23. At this time, in hydrogen peroxide removal chamber 23, a potential difference generated at the interface between different ion exchange materials by the applied current causes a water dissociation reaction (H2O → H + +OH - ) occurs simultaneously, and hydrogen ions (H + ) and hydroxide ion (OH - ) is generated. The interface between different kinds of ion exchange materials is, for example, the interface between an anion exchange membrane and a cation exchanger, the interface between a cation exchange membrane and an anion exchanger, the interface between a cation exchanger and an anion exchanger, or the interface between an anion exchange membrane and a cation exchange membrane. The hydrogen ions and hydroxide ions thus generated exchange the ion components previously adsorbed on the ion exchanger in the hydrogen peroxide removal chamber 23, and are desorbed from the ion exchanger. Among the desorbed ion components, anions move through the anion exchange membrane 32 to the first concentration chamber 22 closer to the anode 11, and are discharged from the first concentration chamber 22 as concentrated water. Eventually, the anion components in the water to be treated that are supplied to the hydrogen peroxide removal chamber 23 move to the first concentration chamber 22 and are discharged, and at the same time, the ion exchanger in the hydrogen peroxide removal chamber 23 is also regenerated. Electrode water is discharged from the anode chamber 21 and the cathode chamber 25, respectively. The DC voltage may be applied continuously or intermittently while the water to be treated is passing through the treatment system.

[0023] There are no particular limitations on the feed water passed through the concentration chambers 22, 24 and the electrode chambers (i.e., the anode chamber 21 and the cathode chamber 25), and independent feed waters may be used for each, or the same feed water may be branched and used. Furthermore, the feed water may be the water to be treated or the treated water discharged from the hydrogen peroxide removal chamber 23, or a separate system of feed water not containing hydrogen peroxide may be passed through. In the figure, the flow of the feed water and the water to be treated in the electrode chambers, concentration chambers 22, 24, and hydrogen peroxide removal chamber 23 is parallel to each other, but the water may be passed so as to flow countercurrently between adjacent chambers.

[0024] 1, the water dissociation reaction proceeds efficiently at the interface between anion exchange membrane 81 and cation exchange membrane 33, and a large amount of hydroxide ions are supplied into hydrogen peroxide removal chamber 23 via anion exchange membrane 81. By supplying a large amount of hydroxide ions, the effective electrical resistance of hydrogen peroxide removal chamber 23 can be reduced, and therefore the DC voltage applied between anode 11 and cathode 12 for electrical regeneration of the anion exchanger in hydrogen peroxide removal chamber 23 can also be reduced.

[0025] In the configuration shown in FIG. 1, a basic configuration consisting of [concentration chamber (C) 22|anion exchange membrane (AEM) 32|hydrogen peroxide removal chamber (H) 23|anion exchange membrane (AEM) 81|cation exchange membrane (CEM) 33|concentration chamber (C) 24] is arranged between the anode 11 and the cathode 12. This basic configuration is called a cell set. In practice, a plurality of such cell sets ("N sets" in FIG. 1) are arranged in parallel between the electrodes, and the plurality of cell sets are electrically connected in series with one end serving as the anode 11 and the other end serving as the cathode 12, thereby increasing the processing capacity. In this case, adjacent concentration chambers can be shared between adjacent cell sets, so that the configuration of the hydrogen peroxide removal device based on the present invention can be configured as [anode chamber|CEM|C|X|X|···|X|AEM|cathode chamber], where X represents the repeating unit consisting of [AEM|H|AEM|CEM|C]. In such a series structure, with respect to the hydrogen peroxide removal chamber 23 closest to the anode chamber 21, the anode chamber 21 itself can function as the concentration chamber 22, without an independent concentration chamber 22 being interposed between the anode chamber 21. Similarly, with respect to the hydrogen peroxide removal chamber 23 closest to the cathode chamber 25, the cathode chamber 25 itself can function as the concentration chamber 24, without an independent concentration chamber 24 being interposed between the cathode chamber 25.

[0026] FIG. 2 shows an example in which the anode chamber 21 is filled with a cation exchange resin (CER), the concentration chambers 22, 24 and the cathode chamber 25 are filled with an anion exchange resin (AER), and the hydrogen peroxide removal chamber 23 is filled with an anion exchange resin (Cat. AER) carrying a platinum group metal catalyst, in the configuration shown in FIG. 1. When TOC components in the water to be treated are decomposed and removed by an ultraviolet oxidation device, the water discharged from the ultraviolet oxidation device contains carbonic acid components and a small amount of hydrogen peroxide. When hydrogen peroxide is decomposed and removed from such water, it is preferable to remove carbonic acid components as well as hydrogen peroxide. In the device shown in FIG. 2, hydroxide ions generated by a water dissociation reaction are supplied through an anion exchange membrane 81, so that the hydrogen peroxide removal chamber 23 becomes a basic environment, and the carbonic acid components in the water to be treated are adsorbed to the anion exchanger as carbonate ions or bicarbonate ions, and then ion-exchanged by the hydroxide ions and transferred to the concentration chamber 22 through the anion exchange membrane 32. The regeneration of the anion exchanger by hydroxide ions is also promoted. Therefore, the hydrogen peroxide removal device shown in Figure 2 can decompose and remove hydrogen peroxide in the water to be treated, and can also remove carbon dioxide components from the water to be treated.

[0027] FIG. 3 is a diagram specifically illustrating the operation of the hydrogen peroxide removal device shown in FIG. 2, showing the hydrogen peroxide removal chamber 23 and its vicinity. As shown by the arrows, the flow of water is in the opposite direction between the hydrogen peroxide removal chamber 23 and the concentrating chambers 22 and 24 on both sides of the chamber. Here, the platinum group metal catalyst is made of palladium (Pd), and granular anion exchange resin (Pd AER) carrying the palladium catalyst is filled in the hydrogen peroxide removal chamber 23 as an anion exchanger. The concentrating chambers 22 and 24 are filled with granular anion exchange resin not carrying a metal catalyst as an anion exchanger. As shown in the figure, when a direct current is applied between the anode 11 and the cathode 12, a dissociation reaction of water proceeds at the interface between the anion exchange membrane 81 and the cation exchange membrane 33 due to the potential difference generated by the current, generating hydrogen ions and hydroxide ions. The hydrogen ions move to the concentrating chamber 24 via the cation exchange membrane 33, and the hydroxide ions move to the hydrogen peroxide removal chamber 23 via the anion exchange membrane 81. In the following description, the granular anion exchange resin supporting a palladium catalyst (Pd AER) is also referred to as Pd-supported anion exchange resin (Pd AER).

[0028] 2 and 3, the anion exchange membrane 81 is not superimposed on the cation exchange membrane 33, and the hydrogen peroxide removal chamber 23 and the concentrating chamber 24 on the cathode 12 side are partitioned only by the cation exchange membrane 33. In this case, in the hydrogen peroxide removal chamber 23, at the position where the Pd-loaded anion exchange resin (Pd AER) contacts the cation exchange membrane 33, weak acid components such as free carbonic acid that have diffused from the concentrating chamber 24 through the cation exchange membrane 33 can be ionized and captured by an ion exchange reaction. For example, carbonic acid is converted to carbonate ions or bicarbonate ions (hydrogen carbonate ions) by the Pd-loaded anion exchange resin (Pd AER) and captured. The captured anions can move to the concentrating chamber 22 on the anode 11 side through the Pd-loaded anion exchange resin (Pd AER). On the other hand, in the areas where the cation exchange membrane 33 is not in contact with the Pd-loaded anion exchange resin (Pd AER), weak acid components are released from the cation exchange membrane 33 into the liquid phase in the hydrogen peroxide removal chamber 23, and it is believed that some of these components are mixed directly into the treated water.

[0029] In order to prevent weak acid components from being mixed into the treated water discharged from the hydrogen peroxide removal chamber 23, it is effective to overlap the anion exchange membrane 81 on the cation exchange membrane 33. When the anion exchange membrane 81 is overlapped on the cation exchange membrane 33, the weak acid components that have diffused to the hydrogen peroxide removal chamber 23 side via the cation exchange membrane 33 permeate the anion exchange membrane 81. At this time, the weak acid components are converted from neutral molecules to anions by ion exchange inside the anion exchange membrane 81, and therefore become in an ionic form that is easily captured by the Pd-loaded anion exchange resin (Pd AER) inside the hydrogen peroxide removal chamber 23. As a result, the mixing of weak acid components into the treated water is reduced.

[0030] 4 shows an example in which treated water from which hydrogen peroxide has been removed in the hydrogen peroxide removal chamber 23 is used as supply water to the anode chamber 21, the first concentration chamber 22, the second concentration chamber 24, and the cathode chamber 25 in the hydrogen peroxide removal apparatus shown in FIG. A portion of the treated water obtained from the hydrogen peroxide removal chamber 23 is passed through the first concentration chamber 22 and the second concentration chamber 24, and discharged as concentrated water. In addition, a portion of the treated water is passed through the cathode chamber 25, and the discharged electrode water is further passed through the anode chamber 21. By using the treated water from which hydrogen peroxide has been removed as supply water to be passed through the concentration chambers and the electrode chambers, the risk of oxidative deterioration of the ion exchangers contained in the concentration chambers and the electrode chambers is reduced.

[0031] In the hydrogen peroxide removal device of the first embodiment, in addition to the anion exchanger (Cat. AER) supporting a platinum group metal catalyst, an ion exchanger not supporting a metal catalyst can be filled in the hydrogen peroxide removal chamber 23. Such an example will be described below. When the hydrogen peroxide removal chamber 23 is filled with an ion exchanger not supporting a metal catalyst, it is preferable to determine the arrangement of each ion exchanger so that the ion exchanger supporting a metal catalyst is placed in contact with the inlet of the water to be treated in the hydrogen peroxide removal chamber 23 so that the ion exchanger is not deteriorated by hydrogen peroxide. In the following description, an anion exchange resin supporting a platinum group metal catalyst is also called a catalyst-supported anion exchange resin (Cat. AER). When simply referring to an anion exchange resin (AER) and a cation exchange resin (CER), they respectively refer to an anion exchange resin not supporting a metal catalyst and a cation exchange resin not supporting a metal catalyst.

[0032] 5, the hydrogen peroxide removal chamber 23 is filled with a mixture of a catalyst-supported anion exchange resin (Cat. AER) and an anion exchange resin (AER). Note that a cation exchange resin (CER) may be filled in place of the anion exchange resin (AER). In this configuration, the amount of expensive platinum group metal catalyst used can be reduced compared to when only a catalyst-supported anion exchange resin (Cat. AER) is filled in the hydrogen peroxide removal chamber 23, thereby reducing costs.

[0033] In the hydrogen peroxide removal apparatus shown in FIG. 6, a layer of catalyst-supported anion exchange resin (Cat. AER) and a layer of anion exchange resin (AER) are alternately arranged in a multi-layered bed configuration in which the layers are filled in the hydrogen peroxide removal chamber 23, with the layer of catalyst-supported anion exchange resin (Cat. AER) being located upstream along the water flow. FIG. 7 is a diagram specifically illustrating the operation of the hydrogen peroxide removal apparatus shown in FIG. 6, showing the hydrogen peroxide removal chamber 23 and its vicinity. It is assumed that a palladium catalyst is used as the platinum group metal catalyst. As in the case described with reference to FIG. 3, when a direct current is applied between the anode 11 and the cathode 12, the potential difference generated by the current causes a water dissociation reaction to proceed at the interface between the anion exchange membrane 81 and the cation exchange membrane 33, generating hydrogen ions and hydroxide ions. The hydroxide ions migrate from anion exchange membrane 81 to both a layer of anion exchange resin supported by a palladium catalyst, i.e., a Pd-supported anion exchange resin (Pd AER), and a layer of anion exchange resin (AER) not supporting a metal catalyst. In this hydrogen peroxide removal device, hydrogen peroxide is decomposed and removed near the inlet of the water to be treated in hydrogen peroxide removal chamber 23, and desalination of anions is performed throughout hydrogen peroxide removal chamber 23.

[0034] The hydrogen peroxide removal device shown in Fig. 8 is the same as the hydrogen peroxide removal device shown in Fig. 6, except that cation exchange resin (CER) is filled in place of anion exchange resin (AER) in hydrogen peroxide removal chamber 23. Therefore, in hydrogen peroxide removal chamber 23, a layer of catalyst-supported anion exchange resin (Cat. AER) and a layer of cation exchange resin (CER) are filled in a multi-layered bed configuration such that the layer of catalyst-supported anion exchange resin (Cat. AER) is located upstream along the water flow. In this multi-layered bed configuration, anion exchange membrane 81 is not provided at the position where the cation exchange resin (CER) is formed, and the cation exchange resin (CER) and cation exchange membrane 33 are in direct contact with each other.

[0035] FIG. 9 is a diagram specifically illustrating the operation of the hydrogen peroxide removal device shown in FIG. 8, showing the hydrogen peroxide removal chamber 23 and its vicinity. It is assumed that a palladium catalyst is used as the platinum group metal catalyst. As in the case described with reference to FIG. 3, when a direct current is applied between the anode 11 and the cathode 12, a potential difference caused by the current causes a water dissociation reaction to proceed at the interface between the anion exchange membrane 81 and the cation exchange membrane 33, generating hydrogen ions and hydroxide ions. The hydrogen ions move to the concentration chamber 24 via the cation exchange membrane 33, and the hydroxide ions move to the hydrogen peroxide removal chamber 23 via the anion exchange membrane 81. Furthermore, water is dissociated at the interface between the anion exchange membrane 32 and the cation exchange resin (CER) in the hydrogen peroxide removal chamber 23, generating hydrogen ions and hydroxide ions. The hydrogen ions diffuse through the cation exchange resin (CER) to regenerate the cation exchange resin (CER). Cations desorbed from the cation exchange resin (CER) in the hydrogen peroxide removal chamber 23 pass through the cation exchange resin (CER) at a position not overlapping with the anion exchange membrane 81, and move to the concentration chamber 24 on the cathode 12 side. Therefore, in the hydrogen peroxide removal device shown in Figure 8, removal of hydrogen peroxide and desalting of both anions and cations are performed in the hydrogen peroxide removal chamber 23, and at the same time, regeneration of both the catalyst-supported anion exchange resin (Cat. AER) and the cation exchange resin (CER) are performed.

[0036] 10, a layer of catalyst-supported anion exchange resin (Cat. AER), a layer of cation exchange resin (Cat. AER), and a layer of anion exchange resin (AER) are packed in the hydrogen peroxide removal chamber 23 in this order from the upstream side along the water flow in a multi-layered bed configuration. The anion exchange membrane 81 overlapping with the cation exchange membrane 33 is provided at the position where the layer of catalyst-supported anion exchange resin (Cat. AER) is formed, and the cation exchange resin (CER) and the anion exchange resin (AER) are in direct contact with the cation exchange membrane 33. Note that the anion exchange membrane 81 overlapping with the cation exchange membrane 33 may be provided not only at the position where the layer of catalyst-supported anion exchange resin (Cat. AER) is formed, but also at the position where the anion exchange resin (AER) is formed.

[0037] FIG. 11 is a diagram specifically illustrating the operation of the hydrogen peroxide removal device shown in FIG. 10, showing the hydrogen peroxide removal chamber 23 and its vicinity. It is assumed that a palladium catalyst is used as the platinum group metal catalyst. As in the case described with reference to FIG. 3, when a direct current is applied between the anode 11 and the cathode 12, a potential difference caused by the current causes a water dissociation reaction to proceed at the interface between the anion exchange membrane 81 and the cation exchange membrane 33, generating hydrogen ions and hydroxide ions. The hydroxide ions move from the anion exchange membrane 81 to the layer of Pd-supported anion exchange resin (Pd AER). At the same time, water is dissociated at the interface between the anion exchange membrane 32 and the cation exchange resin (CER) in the hydrogen peroxide removal chamber 23, and at the interface between the anion exchange resin (AER) in the hydrogen peroxide removal chamber 23 and the cation exchange membrane 33, generating hydrogen ions and hydroxide ions. The hydrogen ions generated at the interface with the anion exchange membrane 32 diffuse within the cation exchange resin (CER) and regenerate the cation exchange resin (CER). The hydroxide ions generated at the interface with the cation exchange membrane 33 diffuse within the anion exchange resin (AER) and regenerate the anion exchange resin (AER). In the hydrogen peroxide removal chamber 23 of this hydrogen peroxide removal device, removal of hydrogen peroxide and desalting of both anions and cations are also performed, and at the same time, regeneration of each ion exchange resin is performed.

[0038] In the hydrogen peroxide removal apparatus described using Figures 6 to 11, by making hydrogen peroxide removal chamber 23 into a multi-bed configuration, the amount of expensive platinum group metal catalyst used can be reduced compared to when only catalyst-supported anion exchange resin (Cat. AER) is filled in hydrogen peroxide removal chamber 23, thereby reducing costs.

[0039] As described above, the anode chamber can function as a concentration chamber without providing a concentration chamber adjacent to the anode chamber, and similarly, the cathode chamber can function as a concentration chamber without providing a concentration chamber adjacent to the cathode chamber. In the hydrogen peroxide removal device shown in FIG. 12, the anode 11, the anode chamber 26, the anion exchange membrane 32, the hydrogen peroxide removal chamber 23, the anion exchange membrane 81, the cation exchange membrane 33, the cathode chamber 27, and the cathode 12 are arranged in this order. Both the anode chamber 26 and the cathode chamber 27 function as concentration chambers. The anode chamber 26 is filled with anion exchange resin (AER) or cation exchange resin (CER), the hydrogen peroxide removal chamber 23 is filled with a catalyst-supported anion exchange resin (Cat. AER), and the cathode chamber 27 is filled with anion exchange resin (AER) or cation exchange resin (CER). 2, except that the functions of concentration chambers 22, 24 are provided by anode chamber 26 and cathode chamber 27, respectively, and instead, concentration chambers 22, 24 are not provided. Therefore, the hydrogen peroxide removal apparatus shown in FIG. 12 operates in the same way as the hydrogen peroxide removal apparatus shown in FIG. 2.

[0040] Next, a hydrogen peroxide removal device according to a second embodiment of the present invention will be described. In the hydrogen peroxide removal device according to the first embodiment, a desalting chamber is provided between the anode 11 and the cathode 12 on the cathode side or the anode side of the hydrogen peroxide removal chamber 23 via an intermediate ion exchange membrane, and the treated water obtained by passing the water to be treated through the hydrogen peroxide removal chamber is passed through the desalting chamber. The desalting chamber is filled with an ion exchanger. By configuring in this way, it is possible to simultaneously remove hydrogen peroxide from the water to be treated and desalt it, and it is possible to produce pure water and ultrapure water of high purity. The intermediate ion exchange membrane may be an anion exchange membrane or a cation exchange membrane, or may be a composite membrane such as a bipolar membrane. In particular, the intermediate ion exchange membrane may be an anion exchange membrane and a cation exchange membrane stacked on each other so that the anion exchange membrane is on the hydrogen peroxide removal chamber 23 side. In the hydrogen peroxide removal device of the second embodiment, when the deionization compartment is filled with at least anion exchange resin, the intermediate ion exchange membrane can be an anion exchange membrane, and the deionization compartment can be partitioned by stacking an anion exchange membrane and a cation exchange membrane on each other, so that the deionization compartment is on the cathode 12 side and the anion exchange membrane is on the hydrogen peroxide removal compartment 23 side.

[0041] FIG. 13 shows one specific example of the hydrogen peroxide removal device of the second embodiment. The hydrogen peroxide removal device shown in FIG. 13 is the hydrogen peroxide removal device shown in FIG. 2, in which a deionization chamber 28 is disposed between the hydrogen peroxide removal chamber 23 and the second concentration chamber 24. The hydrogen peroxide removal chamber 23 and the deionization chamber 28 are separated by an anion exchange membrane 82 and a cation exchange membrane 35 overlapped with each other so that the anion exchange membrane 82 faces the hydrogen peroxide removal chamber 23, and the deionization chamber 28 and the second concentration chamber 24 are separated by a cation exchange membrane 33. The anion exchange membrane 82 and the cation exchange membrane 35 overlapped with each other correspond to an intermediate ion exchange membrane. The water to be treated is supplied to the hydrogen peroxide removal chamber 23, where hydrogen peroxide is decomposed and removed, and then the water is passed through the deionization chamber 28. The treated water from which hydrogen peroxide has been removed and desalted is discharged from the deionization chamber 28. In the hydrogen peroxide removal apparatus shown in FIG. 13 , the anion exchange membrane 32 to the second concentrating chamber 24 are defined as a repeating unit X, and multiple sets of repeating units X can be provided in series between the first concentrating chamber 22 adjacent to the anode chamber 21 and the anion exchange membrane 34 in contact with the cathode chamber 25.

[0042] 13, a water dissociation reaction occurs at the interface between anion exchange membrane 82 and cation exchange membrane 35 to generate hydrogen ions and hydroxide ions, and these hydroxide ions are supplied to hydrogen peroxide removal chamber 23, thereby reducing the effective electrical resistance of hydrogen peroxide removal chamber 23. This also promotes regeneration of the anion exchange resin in hydrogen peroxide removal chamber 23. This is advantageous for removing anion components, particularly carbon dioxide components, as well as hydrogen peroxide.

[0043] The hydrogen peroxide removal apparatus shown in Figure 14 differs from the hydrogen peroxide removal apparatus shown in Figure 13 in that anion exchange resin and cation exchange resin are filled in the desalting compartment 28 in the form of a mixed bed (MB). In Figure 14, the intermediate ion exchange membrane separating the hydrogen peroxide removal compartment 23 and the desalting compartment 28 is formed by overlapping anion exchange membrane 37 arranged on the hydrogen peroxide removal compartment 23 side and cation exchange membrane 83 arranged on the desalting compartment 28 side.

[0044] The hydrogen peroxide removal apparatus shown in Fig. 15 differs from the hydrogen peroxide removal apparatus shown in Fig. 13 in that anion exchange membrane 37 is used as an intermediate ion exchange membrane separating hydrogen peroxide removal chamber 23 and deionization chamber 28, and deionization chamber 28 is filled with a multi-layer bed configuration in which layers of cation exchange resin (CER) and layers of anion exchange resin (AER) are alternately arranged in this order along the direction of water flow. Deionization chamber 28 and concentrating chamber 24 on the cathode 12 side are separated by cation exchange membrane 33, but at the position in deionization chamber 26 where anion exchange resin (AER) is filled, anion exchange membrane 81 is arranged closer to the anode 11 than cation exchange membrane 33, so that the anion exchange membrane 81 and cation exchange membrane 33 overlap each other.

[0045] FIG. 16 is a diagram specifically illustrating the operation of the hydrogen peroxide removal device shown in FIG. 15, showing the hydrogen peroxide removal chamber 23 and the deionization chamber 28 and their vicinity. It is assumed that a palladium catalyst is used as the platinum group metal catalyst. As in the case described with reference to FIG. 3, when a direct current is applied between the anode 11 and the cathode 12, a potential difference caused by the current causes a water dissociation reaction to proceed at the interface between the anion exchange membrane 81 and the cation exchange membrane 33, generating hydrogen ions and hydroxide ions. The hydroxide ions diffuse through the anion exchange resin (AER) in the deionization chamber 28 and move to the hydrogen peroxide removal chamber 23 through the anion exchange membrane 37, which is an intermediate ion exchange membrane. In addition, a water dissociation reaction proceeds at the interface between the anion exchange membrane 37 and the cation exchange resin (CER) in the deionization chamber 28, generating hydrogen ions and hydroxide ions, and these hydrogen ions diffuse through the cation exchange resin (CER). As hydrogen ions diffuse, the region in deionization chamber 28 filled with cation exchange resin (CER) becomes an acidic environment, and the carbonate components in the water to be treated become free carbon dioxide (CO2). This free carbon dioxide reaches the region in deionization chamber 28 filled with anion exchange resin (AER), and since this region is in a basic environment, it is adsorbed by the anion exchange resin as carbonate ions or bicarbonate ions, and then moves to concentration chamber 22 via anion exchange membrane 37, hydrogen peroxide removal chamber 23, and anion exchange membrane 32.

[0046] The hydrogen peroxide removal apparatus shown in Fig. 17 is the hydrogen peroxide removal apparatus shown in Fig. 15, in which the hydrogen peroxide removal chamber 23 and the deionization chamber 28 are interchanged, with the deionization chamber 28 on the anode 11 side and the hydrogen peroxide removal chamber 23 on the cathode 12 side, with an anion exchange membrane 37, which is an intermediate ion exchange membrane, sandwiched between them. In the hydrogen peroxide removal chamber 23, a catalyst-supported anion exchange resin (Cat. AER) is disposed on the inlet side of the water to be treated, and a cation exchange resin (CER) is disposed on the outlet side. The hydrogen peroxide removal chamber 23 and the concentration chamber 24 on the cathode 12 side are partitioned by a cation exchange membrane 33, but at the position where the catalyst-supported anion exchange resin (Cat. AER) is provided, an anion exchange membrane 81 is superimposed on the anode side 11 of the cation exchange membrane 33, and the layer of the catalyst-supported anion exchange resin (Cat. AER) is in contact with the anion exchange membrane 81. The layer of cation exchange resin (CER) is in direct contact with cation exchange membrane 33. Anion exchange resin (AER) is filled in deionization chamber 28. The water to be treated passes through hydrogen peroxide removal chamber 23 and is then supplied to deionization chamber 28, from which hydrogen peroxide has been removed and desalted treated water is discharged.

[0047] FIG. 18 is a diagram specifically illustrating the operation of the hydrogen peroxide removal device shown in FIG. 17, showing the hydrogen peroxide removal chamber 23 and the deionization chamber 28 and their vicinity. It is assumed that a palladium catalyst is used as the platinum group metal catalyst. As in the case described with reference to FIG. 3, when a direct current is applied between the anode 11 and the cathode 12, a potential difference caused by the current causes a water dissociation reaction to proceed at the interface between the anion exchange membrane 81 and the cation exchange membrane 33, generating hydrogen ions and hydroxide ions. The hydroxide ions are supplied to the layer of Pd-supported anion exchange resin (AER) in the hydrogen peroxide removal chamber 23. A water dissociation reaction also proceeds at the interface between the anion exchange membrane 37, which is an intermediate ion exchange membrane, and the cation exchange resin (CER) in the hydrogen peroxide removal chamber 23, and the hydrogen ions generated at this time are supplied to the cation exchange resin (CER) in the hydrogen peroxide removal chamber 23.

[0048] The hydrogen peroxide removal apparatus shown in FIG. 19 is the hydrogen peroxide removal apparatus shown in FIG. 15, except that an auxiliary hydrogen peroxide removal chamber 29 is disposed between the concentrating chamber 24 and the cathode chamber 25 on the cathode 12 side. This hydrogen peroxide removal chamber 29 is also filled with an anion exchanger (Cat. AER) carrying a platinum group metal catalyst, and water to be treated is supplied to the hydrogen peroxide removal chamber 29. The water discharged from the hydrogen peroxide removal chamber 29 is combined with the water discharged from the hydrogen peroxide removal chamber 23 and supplied to the deionization chamber 28. The concentrating chamber 24 and the hydrogen peroxide removal chamber 29 are adjacent to each other with an anion exchange membrane 34 interposed therebetween, and the hydrogen peroxide removal chamber 29 and the cathode chamber 25 are adjacent to each other with an anion exchange membrane 38 interposed therebetween. The hydrogen peroxide removal apparatus shown in FIG. 19 has a plurality of hydrogen peroxide removal chambers 23, 29, and therefore can remove hydrogen peroxide more efficiently.

[0049] In the hydrogen peroxide removal device according to the present invention described above, a DC voltage is applied between the anode 11 and the cathode 12 to electrically regenerate the ion exchanger, for example, granular ion exchange resin, in the hydrogen peroxide removal chamber 23, while removing and desalination hydrogen peroxide. In order to reduce the voltage applied between the anode 11 and the cathode 12, it is effective to pack the ion exchanger densely in the hydrogen peroxide removal chamber 23 within a range in which water flow is not hindered. It is also known that the particle size of an ion exchanger, particularly an ion exchange resin, changes depending on its water content and ion form. When the ion form is the regenerated form, that is, when hydroxide ions are adsorbed to the ion exchange group in the case of an anion exchanger, or when hydrogen ions are adsorbed to the ion exchange group in the case of a cation exchanger, the particle size becomes larger than when the ion form is other than the regenerated form (for example, when chloride ions or sodium ions are adsorbed), that is, when the ion exchanger is in the salt form. Moreover, the particle size becomes larger when the water content of the ion exchanger is large. Ion exchangers, particularly ion exchange resins, are elastic and have the property of being deformed when pressure is applied and returning to their original shape when pressure application is stopped. Therefore, assuming that hydrogen peroxide removal chamber 23 does not deform, it is preferable to fill hydrogen peroxide removal chamber 23 with ion exchangers in a small particle size state, and then expand the ion exchangers by passing water through or by electrical regeneration so that the ion exchangers are densely packed inside hydrogen peroxide removal chamber 23. However, if the ion exchangers are present in hydrogen peroxide removal chamber 23 too densely, this is undesirable as it will hinder the passage of water through hydrogen peroxide removal chamber 23.

[0050] In the hydrogen peroxide removal apparatus according to the present invention, it is preferable that the volume of the ion exchanger in a free state that is removed from hydrogen peroxide removal chamber 23 after a DC voltage is applied between anode 11 and cathode 12 to pass the water to be treated through hydrogen peroxide removal chamber 23 is 102% or more and 125% or less of the volume of hydrogen peroxide removal chamber 23. Here, the volume of the ion exchanger in a free state refers to the apparent volume including the voids between particles when the ion exchanger is not restrained by hydrogen peroxide removal chamber 23.

[0051] The anion exchanger used in the hydrogen peroxide removal device according to the present invention is not particularly limited, regardless of whether it is used to support a metal catalyst or not, and a monolithic porous anion exchanger or an anion exchange resin is preferably used. The anion exchange membrane is not particularly limited, but for example, a homogeneous anion exchange membrane or a heterogeneous anion exchange membrane is preferably used. The cation exchanger is not particularly limited, but for example, a monolithic porous cation exchanger or a cation exchange resin is preferably used. The cation exchange membrane is not particularly limited, but for example, a homogeneous cation exchange membrane or a heterogeneous cation exchange membrane is preferably used. In addition, the intermediate ion exchange membrane is not particularly limited, but for example, a homogeneous anion exchange membrane or a heterogeneous anion exchange membrane, a homogeneous cation exchange membrane or a heterogeneous cation exchange membrane, a bipolar membrane, etc. are preferably used.

[0052] The parent resin of the anion exchange resin or cation exchange resin is not particularly limited, but is preferably an organic polymer having a three-dimensional mesh structure. For example, examples of the parent organic polymer include a styrene-divinylbenzene copolymer (styrene-based) and an acrylic acid-divinylbenzene copolymer (acrylic-based).

[0053] Further, the types of anion exchangers include weakly basic anion exchangers, strongly basic anion exchangers, etc. The types of cation exchangers include weakly acidic cation exchangers, strongly acidic cation exchangers, etc. The ion exchangers carrying a platinum group metal catalyst used in the present invention are those in which particles of a platinum group metal catalyst are carried on the above-mentioned cation exchangers and anion exchangers.

[0054] There is no particular restriction on the manufacturing method of the ion exchanger carrying the platinum group metal catalyst used in the present invention, and the ion exchanger carrying the platinum group metal catalyst can be obtained by carrying platinum group metal particles on the ion exchanger by a known method. For example, there is a method in which the anion exchanger is immersed in an aqueous hydrochloric acid solution of palladium chloride, the chloropalladate anions are adsorbed on the anion exchanger by ion exchange, and then the anion exchanger is contacted with a reducing agent to carry the palladium metal nanoparticles on the anion exchanger. Alternatively, there is a method in which the anion exchanger is packed in a column, an aqueous hydrochloric acid solution of palladium chloride is passed through the column to adsorb the chloropalladate anions on the anion exchanger by ion exchange, and then the reducing agent is passed through the column to carry the palladium metal nanoparticles on the anion exchanger. The reducing agent used in these methods is not particularly limited, and examples thereof include alcohols such as methanol, ethanol, and isopropanol; carboxylic acids such as formic acid, oxalic acid, citric acid, and ascorbic acid; ketones such as acetone and methyl ethyl ketone; aldehydes such as formaldehyde and acetaldehyde; sodium borohydride; and hydrazine.

[0055] The water to be treated that is supplied to the hydrogen peroxide removal device according to the present invention is not particularly limited as long as it contains hydrogen peroxide, and the hydrogen peroxide concentration may be, for example, 1 μg / L or more, 5 μg / L or more, 10 μg / L or more, 100 μg / L or more, or 1000 μg / L or more. The water to be treated may also contain a carbonate component. Here, the carbonate component is H2CO3, HCO3 - , CO3 2-Carbonate components are generated when TOC components are decomposed and removed, for example, by an ultraviolet oxidation device. In this specification, the total amount of these carbonate components is called "total carbonic acid" and its concentration is expressed as a CO2 equivalent concentration (as CO2). The concentration of total carbonic acid in the water to be treated is not particularly limited, but may be, for example, 0.01 mg / L (as CO2) or more, 0.1 mg / L (as CO2) or more, or 1.0 mg / L (as CO2) or more. The conductivity of the water to be treated is also not particularly limited, but may be, for example, 0.1 μS / cm or more, or 1 μS / cm or more. The water to be treated may also contain salt components such as sodium. The concentration of sodium contained in the water to be treated is not particularly limited, but may be, for example, 1 μg / L or more, 10 μg / L or more, or 100 μg / L or more.

[0056] In the present invention, the space velocity of the water to be treated relative to the packed volume of the ion exchanger carrying a platinum group metal catalyst is not particularly limited as long as it can remove hydrogen peroxide. -1 That's it, 100h -1 More than 200h -1 The removal rate of hydrogen peroxide removed from the water to be treated is not particularly limited, but examples include 60% or more, 80% or more, 90% or more, and 95% or more.

[0057] In the present invention, the thickness of the hydrogen peroxide removal chamber 23 is preferably 9 mm or more and 30 mm or less. Here, the thickness of the hydrogen peroxide removal chamber 23 refers to the size of the hydrogen peroxide removal chamber 23 along the direction of voltage application when a DC voltage is applied between the anode 11 and the cathode 12, and the thickness direction of the hydrogen peroxide removal chamber 23 is generally perpendicular to the flow direction of the water to be treated in the hydrogen peroxide removal chamber 23. If the thickness of the hydrogen peroxide removal chamber 23 is too thin, the flow rate of the water to be treated that can be treated becomes too small. On the other hand, if the thickness of the hydrogen peroxide removal chamber 23 is too thick, the DC voltage to be applied between the anode 11 and the cathode 12 becomes excessively high, and the amount of hydroxide ions and hydrogen ions generated by dissociation of water is insufficient compared to the amount of the ion exchanger, so that electrical regeneration of the ion exchanger in the hydrogen peroxide removal chamber 23 is not performed sufficiently.

[0058] The hydrogen peroxide removal device according to the present invention can be incorporated, for example, into a pure water production system or an ultrapure water production system. Hereinafter, a pure water production system and an ultrapure water production system incorporating the hydrogen peroxide removal device according to the present invention will be described.

[0059] FIG. 20 shows an example of the configuration of a pure water production system in the prior art. In this pure water production system, a raw water tank 41 for storing raw water, a first reverse osmosis membrane device 51, a second reverse osmosis membrane device 52, a reverse osmosis membrane treated water tank 42, an electric deionizer (EDI) 54, an EDI treated water tank 43, an ultraviolet oxidation device (UV) 55, a non-regenerative ion exchange resin (CP) 56, and a degassing membrane (MD) 58 are arranged in this order, and the raw water is treated in this order. As a result, pure water is finally produced. In this pure water production system, when the downstream equipment becomes full of water, a circulation operation is performed within the system, but there is a risk that the ion exchanger in the electric deionizer 54 will be oxidized and deteriorated by hydrogen peroxide generated by the ultraviolet oxidation device 55. Therefore, when circulating within the system, it is necessary to circulate the produced pure water to the EDI treated water tank 43 and circulate the treated water from the electrodeionization device 54 to the reverse osmosis treated water tank 42 so that the treated water from the ultraviolet oxidation device 55 is not circulated to the electrodeionization device 54. Such a pure water production system requires multiple lines and EDI treated water tanks for circulation, resulting in a complex configuration.

[0060] FIG. 21 shows an example of the configuration of a pure water production system equipped with a hydrogen peroxide removal device based on the present invention. In the pure water production system 300 shown in the figure, a raw water tank 41, a first reverse osmosis membrane device 51, a second reverse osmosis membrane device 52, a reverse osmosis membrane treated water tank 42, an ultraviolet oxidation device (UV) 55, a hydrogen peroxide removal device 100, an electric deionization device (EDI) 54, and a degassing membrane (MD) 58 are arranged in this order, and the raw water is treated in this order, resulting in the production of pure water. The hydrogen peroxide removal device 100 used here may be any type of hydrogen peroxide removal device based on the present invention, but it is preferable to use any of the hydrogen peroxide removal devices shown in FIG. 1 to FIG. 19. In this pure water production system, when the downstream equipment to which the pure water is supplied is full, the produced pure water is circulated to the reverse osmosis membrane treated water tank 42. That is, by arranging the hydrogen peroxide removal device 100 after the ultraviolet oxidation device 55, it is possible to prevent the hydrogen peroxide generated by the ultraviolet oxidation device 55 from affecting the electrodeionization device 54. As is clear from the above description, the hydrogen peroxide removal device 100 itself has the same desalination performance as an electrodeionization device, and this configuration makes it possible to obtain pure water of high purity equivalent to that obtained when two electrodeionization devices are arranged in series. Depending on the desalination performance required for the pure water production system, the outlet water of the hydrogen peroxide removal device 100 may be directly supplied to the deaeration membrane (MD) 58 without providing the electrodeionization device (EDI) 54. By providing a single system for circulating the treated water, the EDI treated water tank and the EDI treated water circulation line required for the system shown in FIG. 20 are no longer necessary, making it possible to provide a low-cost pure water production system.

[0061] 21, at least a portion of the treated water from the deaeration membrane (MD) 58 is circulated to the reverse osmosis membrane treated water tank 42, but treated water from the hydrogen peroxide removal apparatus 100 or the electrical deionization apparatus (EDI) 54 may also be circulated to the reverse osmosis membrane treated water tank 42. In addition, water that bypasses the ultraviolet oxidation device 55 may be, and is preferably, used as the supply water passed through the concentration chamber and electrode chamber of the hydrogen peroxide removal apparatus 100. By using water that bypasses the ultraviolet oxidation device 55, water with a low hydrogen peroxide concentration or no hydrogen peroxide is supplied to the concentration chamber and electrode chamber, so deterioration of the ion exchanger filled in the concentration chamber and electrode chamber can be suppressed.

[0062] In a pure water production system, a carbon dioxide removal means may be provided in the upstream of the hydrogen peroxide removal device. When the amount of carbon dioxide components in the water being treated that is supplied to the hydrogen peroxide removal device is reduced, it becomes possible to lower the voltage applied to the hydrogen peroxide removal device, thereby reducing power consumption. Carbon dioxide removal means may include a reverse osmosis (RO) device, the addition of a basic agent to the reverse osmosis device, and, although not shown in FIG. 21, a degassing membrane (MD), a decarbonation tower, an anion exchange resin tower, etc.

[0063] FIG. 22 shows an example of the configuration of an ultrapure water production system incorporating a hydrogen peroxide removal device according to the present invention. The illustrated ultrapure water production system 400 uses the pure water production system 300 shown in FIG. 21 as a primary pure water system, and further includes a subsystem to produce ultrapure water. In the subsystem, a pure water tank 45 is provided to store the primary pure water from the primary pure water system, and an ultraviolet oxidation device (UV) 61, a non-regenerative ion exchange resin (CP) 63, a degassing membrane (MD) 65, and an ultrafiltration membrane (UF) 67 are arranged in this order at the outlet of the pure water tank 45, so that the primary pure water is treated in this order to produce ultrapure water. A part of the produced ultrapure water is circulated to the pure water tank 45. A microfiltration membrane may be used instead of the ultrafiltration membrane (UF) 67. Also, the primary pure water system may be configured without providing an electrical regenerative deionization device (EDI) 54.

[0064] The ultrapure water production system shown in Fig. 23 is obtained by rearranging the order of the ultraviolet oxidation device (UV) 55, hydrogen peroxide removal device 100, and electrodeionization device (EDI) 54 in the primary pure water system of the ultrapure water production system shown in Fig. 22 to the electrodeionization device (EDI) 54, ultraviolet oxidation device (UV) 55, and hydrogen peroxide removal device 100. The ultrapure water production system shown in Fig. 24 is obtained by providing a boron removal device such as a boron-selective ion exchange resin (B IER) 57 or a boron-selective adsorbent in a position subsequent to the electrodeionization device (EDI) 54 and preceding the ultraviolet oxidation device (UV) in the primary pure water system of the ultrapure water production system shown in Fig. 23.

[0065] In the ultrapure water production system, the hydrogen peroxide removal device 100 according to the present invention can be disposed in a subsystem. FIG. 25 shows the ultrapure water production system shown in FIG. 23, except that the hydrogen peroxide removal device 100 is removed from the primary pure water system and the outlet water of the ultraviolet oxidation device (UV) 55 is directly supplied to the degassing membrane (MD) 58, and the hydrogen peroxide removal device 100 is provided in place of the non-regenerative ion exchange resin (CP) 63 in the subsystem. In the primary pure water system, the non-regenerative ion exchange resin (CP) 56 is provided in place of the hydrogen peroxide removal device 100. Since the hydrogen peroxide removal device 100 can be provided with desalination performance, even if the hydrogen peroxide removal device 100 is provided in place of the non-regenerative ion exchange resin (CP) 63 in the subsystem, the quality of the ultrapure water obtained as the outlet water of the ultrafiltration membrane (UF) 67 does not deteriorate. In the subsystem, the non-regenerative ion exchange resin (CP) 63 may be left as it is and the hydrogen peroxide removal device 100 may be provided. In this way, ionic components that could not be removed by the hydrogen peroxide removal apparatus 100 can be removed by the non-regenerative ion exchange resin (CP) 63, and furthermore, hydrogen peroxide that cannot be removed by the non-regenerative ion exchange resin (CP) 63 can be removed, thereby complementing each function. When both the hydrogen peroxide removal apparatus 100 and the non-regenerative ion exchange resin (CP) 63 are provided in series, water may be passed through the hydrogen peroxide removal apparatus 100 first, or may be passed through the non-regenerative ion exchange resin (CP) 63 first. EXAMPLES

[0066] Next, the present invention will be described in more detail with reference to examples.

[0067] [Example 1] The hydrogen peroxide removal device shown in Figures 2 and 3 was assembled such that multiple hydrogen peroxide removal chambers 23 were arranged between the anode 11 and the cathode 12. A 1 cm thick frame having a 10 cm x 10 cm square opening was prepared, and two of these frames were stacked and filled with regenerated Pd-loaded anion exchange resin (Pd AER) to form a 2 cm thick hydrogen peroxide removal chamber 23. The hydrogen peroxide removal chamber 23 was partitioned on the anode 11 side by an anion exchange membrane 32, and on the cathode 12 side by a membrane in which an anion exchange membrane 81 and a cation exchange membrane 33 were stacked together so that the cation exchange membrane 33 was on the cathode 12 side. The electrode chambers (anode chamber 21 and cathode chamber 25) and concentration chambers 22 and 24 were each 1 cm thick by filling them with ion exchangers using the same frame. Water having a conductivity of 1.3 μS / cm, a hydrogen peroxide concentration of 97.5 μg / L, and a total carbonate concentration of 0.103 mg / L (as CO2) was supplied to the electrode chambers, concentration chambers 22, 24, and hydrogen peroxide removal chamber 23, and a DC voltage was applied between anode 11 and cathode 12 so as to obtain a current of 1.04 A. The flow rate of the water to be treated into hydrogen peroxide removal chamber 23 was set to 88 L / h.

[0068] Approximately 1000 hours had passed since the start of water flow through the hydrogen peroxide removal apparatus and the application of DC voltage, and the system had stabilized. The hydrogen peroxide concentration in the treated water discharged from hydrogen peroxide removal chamber 23 was then determined, and the hydrogen peroxide removal rate in this hydrogen peroxide removal apparatus was calculated. At the same time, the resistivity of the water to be treated and the value of the DC voltage being applied at that time were determined, and the power consumption per unit flow rate of the water to be treated was calculated based on the applied voltage and current value. The results are shown in Table 1. After these measurements were completed, the Pd-supported anion exchange resin (Pd AER) was removed from hydrogen peroxide removal chamber 23 and its volume in the free state was determined, which was 95-100% of the volume of hydrogen peroxide removal chamber 23.

[0069] [Comparative Example 1] A hydrogen peroxide removal apparatus similar to that of Example 1 was assembled, in which hydrogen peroxide removal chamber 23 and concentration chamber 24 located on the side of cathode 12 were separated only by cation exchange membrane 33. Figure 26 shows the main parts of the hydrogen peroxide removal apparatus of Comparative Example 1. In the hydrogen peroxide removal apparatus of Comparative Example 1, only one frame used in Example 1 is used, so that hydrogen peroxide removal chamber 23 is 1 cm thick.

[0070] The same measurements as in Example 1 were carried out using the same water as in Example 1, with the flow rate of the water to be treated into hydrogen peroxide removal chamber 23 set to 56 L / h and the current flowing between anode 11 and cathode 12 set to 0.66 A. The results are shown in Table 1. After the measurements were completed, the Pd-loaded anion exchange resin (Pd AER) was removed from hydrogen peroxide removal chamber 23 and its volume in the free state was measured; it was 95 to 100% of the volume of hydrogen peroxide removal chamber 23.

[0071] In the hydrogen peroxide removal device of Comparative Example 1, a dissociation reaction of water proceeds at the interface between the Pd-loaded anion exchange resin (Pd AER) and the cation exchange membrane 33. The hydrogen ions generated at this time are released into the concentration chamber 24 adjacent to the hydrogen peroxide removal chamber 23, and react with the carbonic acid component contained in the water in the concentration chamber 24 to generate free carbonic acid. Since the free carbonic acid does not have an electric charge, it is not affected by the charge repulsion of the cation exchange membrane 33, and diffuses from the concentration chamber 24 into the hydrogen peroxide removal chamber 23 through the cation exchange membrane 33. Since this free carbonic acid is not in an ionic form, it is difficult for it to be adsorbed by the Pd-loaded anion exchange resin (Pd AER) in the hydrogen peroxide removal chamber 23, and leaks into the treated water, causing a decrease in water quality. In order for the carbonic acid component to be adsorbed by the Pd-loaded anion exchange resin (Pd AER), it must be converted into carbonate ions or bicarbonate ions. In contrast, in the hydrogen peroxide removal apparatus of Example 1, an anion exchange membrane 81 is superimposed on the cation exchange membrane 33 through which free carbon dioxide diffuses. Therefore, the free carbon dioxide is reliably converted into carbonate ions and bicarbonate ions as it passes through the anion exchange membrane 81 before being released into the hydrogen peroxide removal chamber 23, so that deterioration of the water quality in the treated water is unlikely to occur.

[0072] [Comparative Example 2] A hydrogen peroxide removal apparatus similar to that of Example 1 was assembled, in which hydrogen peroxide removal chamber 23 and concentration chamber 24 located on the side of cathode 12 were separated only by cation exchange membrane 33. Figure 27 shows the main parts of the hydrogen peroxide removal apparatus of Comparative Example 2. In the hydrogen peroxide removal apparatus of Comparative Example 2, hydrogen peroxide removal chamber 23 has a thickness of 2 cm, the same as that of Example 1.

[0073] The same measurements as in Example 1 were carried out using the same water as in Example 1, with the flow rate of the water to be treated into hydrogen peroxide removal chamber 23 set to 88 L / h, and the current flowing between anode 11 and cathode 12 set to 1.04 A. The results are shown in Table 1. After the measurements were completed, the Pd-loaded anion exchange resin (Pd AER) was removed from hydrogen peroxide removal chamber 23 and its volume in a free state was measured, which was 95 to 100% of the volume of hydrogen peroxide removal chamber 23. Note that in the hydrogen peroxide removal device of Comparative Example 2, a water dissociation reaction also proceeds at the interface between the Pd-loaded anion exchange resin (Pd AER) and cation exchange membrane 33, and the hydrogen ions generated at this time diffuse into concentration chamber 24 via cation exchange membrane 33, producing free carbon dioxide.

[0074] [Table 1]

[0075] Comparing Example 1 with Comparative Examples 1 and 2, the hydrogen peroxide removal rates were almost the same, and Example 1 had the highest resistivity of the treated water. In Example 1, the DC voltage applied between the anode 11 and the cathode 12 was 10.0 V, whereas Comparative Example 1 applied voltage was 14.6 V, which was about 1.5 times that of Example 1, despite the current value being smaller than that of Example 1. In Comparative Example 2, which had the same current value as Example 1, the applied voltage was 29.2 V, which was about three times that of Example 1. As the applied voltage increased, the power consumption per unit flow rate of the treated water was 0.11 W·h / L in Example 1, whereas it was 0.17 W·h / L in Comparative Example 1, which was about 1.5 times that of Example 1, and 0.33 W·h / L in Comparative Example 2, which was about three times that of Example 1. Thus, in Example 1, the applied voltage can be reduced and the power consumption per amount of treated water can be reduced because, in Example 1, the water dissociation reaction occurs over the entire surface of the interface between the anion exchange membrane 81 and the cation exchange membrane 33, so that a large amount of hydroxide ions used for electrical regeneration of the ion exchanger are supplied to the hydrogen peroxide removal chamber 23. In contrast, in Comparative Examples 1 and 2, the water dissociation reaction proceeds only in a relatively narrow area, namely, the contact point between the Pd-supported anion exchange resin (Pd AER) and the cation exchange membrane 33, so that the amount of hydroxide ions produced is small, resulting in an increase in the applied voltage. Also, the resistivity of the treated water is high in Example 1 because, as described above, the free carbonic acid diffusing from the concentration chamber 24 to the hydrogen peroxide removal chamber 23 is converted to carbonate ions or bicarbonate ions when diffusing through the anion exchange membrane 81.

[0076] [Example 2] The filling rate of the ion exchanger in the hydrogen peroxide removal chamber was examined. The filling rate of the ion exchanger here refers to a value obtained by dividing the volume of the ion exchanger in a free state taken out of the hydrogen peroxide removal chamber after applying a DC voltage between the anode and the cathode and passing the water to be treated through the hydrogen peroxide removal chamber by the volume of the hydrogen peroxide removal chamber. A hydrogen peroxide removal device having the same configuration as in Example 1 was used, and the hydrogen peroxide removal chamber 23 was filled with a salt-type Pd-supported anion exchange resin (Pd AER). The hydrogen peroxide removal devices of Examples 2-1 and 2-2 were constructed by changing the filling amount at this time. Water having a conductivity of 1.3 μS / cm, a hydrogen peroxide concentration of 97.5 μg / L, and a total carbonate concentration of 0.103 mg / L (as CO2) was supplied to the electrode chamber, the concentration chambers 22 and 24, and the hydrogen peroxide removal chamber 23, and a voltage was applied between the anode 11 and the cathode 12 so that the current was 1.04 A. The flow rate of the water to be treated into the hydrogen peroxide removal chamber 23 was set to 88 L / h.

[0077] For each of the hydrogen peroxide removal devices of Examples 2-1 and 2-2, the concentration of hydrogen peroxide contained in the treated water discharged from hydrogen peroxide removal chamber 23 was determined when the system stabilized approximately 500 hours after water flow through the hydrogen peroxide removal device and application of DC voltage began, and the hydrogen peroxide removal rate of this hydrogen peroxide removal device was determined. At the same time, the resistivity of the water to be treated, the value of the DC voltage applied at that time, and the power consumption per amount of treated water were determined. The results are shown in Table 2. After these measurements were completed, the Pd-supported anion exchange resin (Pd AER) was removed from hydrogen peroxide removal chamber 23 and its volume in a free state was determined to determine the filling rate, which was 110-115% in Example 2-1 and 95-100% in Example 2-2.

[0078] [Table 2]

[0079] Comparing Example 2-1 and Example 2-2, the hydrogen peroxide removal rate is almost the same, but there is a slight difference in the resistivity of the treated water. However, in Example 2-1 with a high filling rate, the applied voltage is 6.5 V, whereas in Example 2-2 with a low filling rate, the applied voltage is 29.2 V, which is about 4.5 times that of Example 2-1. Even compared to Example 1, the applied voltage could be lowered in Example 2-1 with a higher filling rate. It was found that the applied voltage could be lowered by increasing the filling rate within a range that does not prevent the flow of the water to be treated. In addition, it is considered that the resistivity of the treated water in Example 2-1 was slightly higher and more favorable because the voltage was lowered and the current flowed more easily.

[0080] [Example 3] The relationship between the packing rate of the ion exchanger carrying a platinum group metal catalyst and the electrical resistance of the hydrogen peroxide removal chamber was investigated. 3 A space was prepared, and this space was filled with a salt-form Pd-loaded anion exchange resin to correspond to the packing rate, and ultrapure water at a temperature of 25°C was passed through it. An LCR meter was then used to apply an AC voltage of 1 kHz and 1000 mV between the plate electrodes to measure the impedance between the plate electrodes, and this was evaluated as the electrical resistance when a DC voltage was applied during operation as a hydrogen peroxide removal device. The results are shown in Figure 28. As shown in Figure 28, if the packing rate is less than 0.95 (i.e., 95%), the electrical resistance becomes significantly high. Therefore, it was found that the packing rate is preferably 0.95 to 1.25, and more preferably 1.02 to 1.25. [Explanation of symbols]

[0081] 11 Anode 12 Cathode 21,26 Anode chamber 22,24 Concentration chamber 23,29 Hydrogen peroxide removal chamber 25,27 Cathode chamber 28 Desalination room 31,33,35,83 Cation Exchange Membrane (CEM) 32,34,37,38,81,82 Anion exchange membrane (AEM) 51,52 Reverse osmosis membrane equipment 54 Electrodeionizer (EDI) 55,61 Ultraviolet oxidation equipment (UV) 56,63 Non-regenerative ion exchange resin (CP) 57 Boron-selective ion exchange resin (B IER) 58,65 Degassing membrane (MD) 67 Ultrafiltration membrane (UF) 100 Hydrogen peroxide removal device 300 Pure water production equipment 400 Ultrapure water production equipment

Claims

1. A method for removing hydrogen peroxide contained in water to be treated, comprising the steps of: The method includes a step of passing the water to be treated through a hydrogen peroxide removal chamber filled with an ion exchanger and disposed between an anode and a cathode while applying a DC voltage between the anode and the cathode, At least a portion of the ion exchanger packed in the hydrogen peroxide removal chamber is an ion exchanger carrying a metal catalyst having hydrogen peroxide decomposition ability, A method according to the present invention, in which a first cation exchange membrane and a first anion exchange membrane are stacked on top of each other and disposed between at least one of the hydrogen peroxide removal chambers and the cathode, such that the first cation exchange membrane is on the cathode side and the first anion exchange membrane is on the at least one of the hydrogen peroxide removal chambers.

2. 2. The method of claim 1, wherein the metal catalyst is a platinum group metal catalyst and the ion exchanger on which the metal catalyst is supported is an anion exchanger.

3. 3. The method according to claim 1, wherein the hydrogen peroxide removal chamber is defined on the cathode side by the first anion exchange membrane.

4. A hydrogen peroxide removal device for removing hydrogen peroxide contained in water to be treated, an anode and a cathode; a hydrogen peroxide removal chamber provided between the anode and the cathode and filled with an ion exchanger; a first cation exchange membrane and a first anion exchange membrane disposed between at least one of the hydrogen peroxide removal chambers and the cathode; having At least a portion of the ion exchanger packed in the hydrogen peroxide removal chamber is an ion exchanger carrying a metal catalyst having hydrogen peroxide decomposition ability, the first cation exchange membrane and the first anion exchange membrane are arranged so as to be overlapped with each other, such that the first cation exchange membrane is on the cathode side and the first anion exchange membrane is on the at least one hydrogen peroxide removal chamber side; A hydrogen peroxide removal device in which a DC voltage is applied between the anode and the cathode.

5. 5. The hydrogen peroxide removal apparatus according to claim 4, wherein the metal catalyst is a platinum group metal catalyst, and the ion exchanger on which the metal catalyst is supported is an anion exchanger.

6. 6. The hydrogen peroxide removal apparatus according to claim 4, wherein the hydrogen peroxide removal chamber is partitioned on the cathode side by the first anion exchange membrane.

7. 7. The hydrogen peroxide removal apparatus according to claim 4, wherein the bulk volume of the ion exchanger in a free state, including voids between particles of the ion exchanger, which is removed from the hydrogen peroxide removal chamber after a DC voltage is applied between the anode and the cathode to pass the water to be treated through the hydrogen peroxide removal chamber, is 102% or more and 125% or less of the volume of the hydrogen peroxide removal chamber.

8. The hydrogen peroxide removal device according to any one of claims 4 to 7, an ultraviolet oxidation device provided upstream of the hydrogen peroxide removal device; A pure water production apparatus having the above structure.

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