Method for preparing a mixed bed ion exchanger for purifying hydrogen peroxide solution, method for purifying hydrogen peroxide solution, and method for purifying ammonium bicarbonate solution

Abstract

To provide a mixed bed ion exchanger capable of efficiently obtaining a highly pure hydrogen peroxide water suppressed in contamination such as cross contamination, and reduced in a metal content.SOLUTION: A preparation method of a mixed bed ion exchanger for purifying a hydrogen peroxide water includes: a process of contacting a H-type cation exchanger to a highly pure mineral acid solution to obtain a purified H-type cation exchanger; a process of mixing the purified H-type cation exchanger with an OH-type anion exchanger to prepare a mixed bed ion exchanger; and a process of contacting the mixed bed ion exchanger to a carbon dioxide-dissolved water to change the OH-type anion exchanger to a bicarbonate ion-type anion exchanger, or a bicarbonate ion-type and carbonate ion-type anion exchanger, where the obtained mixed bed ion exchanger for purifying a hydrogen peroxide water has a metallic impurity content of 1 mg / L or less, and a total metallic impurity content eluted when a hydrochloric acid having a concentration of 3% is passed with a volume ratio of 25 times amount of 3 mg / L-R or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a mixed-bed ion exchanger for purifying hydrogen peroxide solution and a method for purifying hydrogen peroxide solution using the mixed-bed ion exchanger. [Background technology]

[0002] Hydrogen peroxide is widely used in a wide range of applications, including paper and pulp bleaching, industrial oxidizing agents, wastewater treatment, and cleaning agents in semiconductor manufacturing processes. In particular, hydrogen peroxide is used in large quantities in wet cleaning processes in semiconductor manufacturing, such as ammonia-hydrogen peroxide cleaning to remove particulate contamination and hydrochloric acid-hydrogen peroxide cleaning to ionize and remove metal contamination. High purity is required for the ultrapure water and reagents used in these contamination removal processes, and hydrogen peroxide must also be of a quality that minimizes the content of various impurities. One known method for removing metal components from hydrogen peroxide and purifying it is to contact it with an ion exchange resin. However, to obtain high-purity hydrogen peroxide, the ion exchange resin used in the purification process must contain minimal metal components.

[0003] As a technology for specifying the metal content in an ion exchange resin used to purify hydrogen peroxide, Patent Document 1 discloses a method for purifying hydrogen peroxide using a cation exchange resin with a specified sodium content. Patent Document 2 also discloses a method for purifying hydrogen peroxide using an ion exchange resin with a specified content of aluminum, iron, calcium, and zinc. Meanwhile, the present applicant has proposed a method for producing a mixed bed consisting of an anion exchanger and a cation exchanger, which includes a step of converting the anion exchanger to bicarbonate ion form / carbonate ion form using carbon dioxide-dissolved water (Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-171508 [Patent Document 2] Japanese Patent Application Publication No. 10-259008 [Patent Document 3] International Publication No. 2015 / 098348 [Patent Document 4] Japanese Patent Application Laid-Open No. 2007-117781 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the method described in Patent Document 3, a resin for purifying hydrogen peroxide solution can be prepared without separating a mixed bed consisting of an anion exchanger and a cation exchanger. However, if both the anion exchanger and the cation exchanger contain impurities such as metals, there is a concern that the impurities contained in each resin will leach out when carbon dioxide-dissolved water is passed through the resin, resulting in cross-contamination, such as mutual elimination of the eluted impurities, or impurities eluted from one resin being captured by the other resin. In particular, carbon dioxide-dissolved water is weakly acidic, making such contamination highly likely. Furthermore, because the hydrogen peroxide solution to be purified is also weakly acidic, it is conceivable that a similar phenomenon will occur during the purification of hydrogen peroxide solution. Such resin contamination is a serious issue when purifying high-purity hydrogen peroxide solution, which has metal impurity concentrations at the ng / L level.

[0006] Therefore, an object of the present invention is to provide a mixed-bed ion exchanger for purifying hydrogen peroxide solution, which can suppress cross-contamination and other contamination and efficiently produce high-purity hydrogen peroxide solution with reduced metal content when purifying hydrogen peroxide solution using a mixed-bed ion exchanger containing a cation exchanger and an anion exchanger. Another object of the present invention is to provide a method for purifying high-purity hydrogen peroxide solution using the mixed-bed ion exchanger for hydrogen peroxide solution purification. [Means for solving the problem]

[0007] In view of the above object, the present inventors have conducted extensive research and have found that the above problem can be solved by mixing an anion exchanger and a cation exchanger to be used in purifying hydrogen peroxide solution, and reducing the amount of metal impurities contained in at least the cation exchanger using a high-purity mineral acid solution before forming a mixed bed, thereby completing the present invention.

[0008] That is, the present invention provides a cation exchanger preparation step of obtaining a purified H-form cation exchanger (C2) by contacting an H-form cation exchanger (C1) with a mineral acid solution containing metal impurities in an amount of 1 mg / L or less and having a concentration of 5% or more; a mixed-bed ion exchanger preparation step of mixing the H-form cation exchanger (C2) with the OH-form anion exchanger (A1) to prepare a mixed-bed ion exchanger (MB1); an anion exchanger conversion step of converting the OH-form anion exchanger (A1) into a bicarbonate-form or bicarbonate-form and carbonate-form anion exchanger (A2) by contacting the mixed-bed ion exchanger (MB1) with water containing dissolved carbon dioxide, thereby obtaining a mixed-bed ion exchanger (MB2) for hydrogen peroxide purification; This is a method for preparing a mixed bed ion exchanger (MB2) for hydrogen peroxide purification, characterized in that the mixed bed ion exchanger (MB2) contains metal impurities in an amount of 1 mg / L or less and the total amount of metal impurities eluted when 25 volumes of 3% hydrochloric acid are passed through the mixed bed ion exchanger (MB2) for hydrogen peroxide purification is 3 mg / L or less.

[0009] The present invention also provides a method for purifying hydrogen peroxide solution, which comprises a step of contacting hydrogen peroxide solution with an ion exchanger, characterized in that the ion exchanger is a mixed bed ion exchanger (MB2) for hydrogen peroxide solution purification prepared by the above-mentioned preparation method. [Effects of the Invention]

[0010] According to the present invention, a mixed-bed ion exchanger for purifying hydrogen peroxide solution containing a cation exchanger and an anion exchanger is provided that suppresses cross-contamination and other contamination and efficiently produces high-purity hydrogen peroxide solution with reduced metal content when purifying hydrogen peroxide solution using such a highly purified mixed-bed ion exchanger. Furthermore, according to the present invention, hydrogen peroxide solution of even higher purity can be obtained by purifying hydrogen peroxide solution using such a highly purified mixed-bed ion exchanger for purifying hydrogen peroxide solution. In particular, when hydrogen peroxide solution is passed through the mixed-bed ion exchanger, metal elution is reduced in the initial stage of flow, resulting in a faster rise in the flow rate, and therefore the amount of hydrogen peroxide solution containing a high metal content in the initial stage of flow can be reduced. In other words, according to the present invention, high-purity hydrogen peroxide solution can be produced economically and efficiently. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a graph showing the results of Examples 3 to 6 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] <Method for preparing a mixed bed ion exchanger for hydrogen peroxide purification> The mixed-bed ion exchanger (MB2) for hydrogen peroxide purification according to the present invention (also referred to as "mixed-bed ion exchanger (MB2)") is a mixed-bed ion exchanger comprising an H-form cation exchanger (C2) and a bicarbonate-form anion exchanger, or a bicarbonate-form anion exchanger and a carbonate-form anion exchanger (collectively referred to as "bicarbonate-form or bicarbonate-form and carbonate-form anion exchanger (A2)" or "anion exchanger (A2)"). The mixed-bed ion exchanger (MB2) for hydrogen peroxide purification is prepared by a method comprising at least the following steps: a cation exchanger preparation step of obtaining a purified H-form cation exchanger (C2) by contacting the H-form cation exchanger (C1) with a mineral acid solution containing metal impurities in an amount of 1 mg / L or less and having a concentration of 5% or more; a mixed-bed ion exchanger preparation step of mixing the H-form cation exchanger (C2) with the OH-form anion exchanger (A1) to prepare a mixed-bed ion exchanger (MB1); An anion exchanger conversion step in which the mixed-bed ion exchanger (MB1) is brought into contact with water dissolved in carbon dioxide to convert the OH-form anion exchanger (A1) in the mixed-bed ion exchanger (MB1) into bicarbonate-form or bicarbonate-form and carbonate-form anion exchanger (A2), thereby obtaining a mixed-bed ion exchanger (MB2) for hydrogen peroxide purification. The mixed bed ion exchanger (MB2) for purifying hydrogen peroxide solution obtained in this manner is characterized by containing less than 1 mg / L of metal impurities and eluting less than 3 mg / L of total metal impurities when 25 times the volume of 3% hydrochloric acid is passed through it. Each of the above steps will now be described in detail.

[0013] [Cation exchanger preparation process] This step is a step of reducing the amount of metal impurities contained in the H-type cation exchanger used in the purification of hydrogen peroxide solution, thereby obtaining a purified H-type cation exchanger, i.e., a step of pretreating the H-type cation exchanger.

[0014] (H-type cation exchanger) The H-form (hydrogen ion form) cation exchanger (C1) can be an H-form cation exchange resin or a monolithic cation exchanger. Because the ion exchange resin is granular, resins of different ionicities can be easily mixed. The monolithic ion exchanger can be thinly cut and stacked, or can be shredded and then mixed. Either the cation exchanger or the anion exchanger described below may be an ion exchange resin, and the other may be a monolithic ion exchanger. Alternatively, both may be ion exchange resins or monolithic ion exchangers. In the present invention, the H-form cation exchanger (C1) is preferably an H-form cation exchange resin.

[0015] The cation exchange resin used in the present invention is not particularly limited, but is preferably an organic polymer-based cation exchange resin having an organic polymer as a base, such as a styrene-based resin or an acrylic-based resin.

[0016] In this specification, the term "styrene-based resin" refers to a resin obtained by homopolymerizing or copolymerizing styrene or a styrene derivative and containing 50% by mass or more of structural units derived from styrene or a styrene derivative. Examples of styrene derivatives include α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, and bromostyrene. As long as the styrene-based resin is primarily composed of a homopolymer or copolymer of styrene or a styrene derivative, it may also be a copolymer with other copolymerizable vinyl monomers. Examples of such vinyl monomers include one or more selected from the group consisting of divinylbenzenes such as o-divinylbenzene, m-divinylbenzene, and p-divinylbenzene; polyfunctional monomers such as alkylene glycol di(meth)acrylates such as ethylene glycol di(meth)acrylate and polyethylene glycol di(meth)acrylate; (meth)acrylonitrile; and methyl (meth)acrylate. Among these, divinylbenzene, ethylene glycol di(meth)acrylate, and polyethylene glycol di(meth)acrylate having an ethylene polymerization number of 4 to 16 are preferred, divinylbenzene and ethylene glycol di(meth)acrylate are more preferred, and divinylbenzene is particularly preferred.

[0017] In addition, in this specification, "acrylic resin" means a resin obtained by homopolymerizing or copolymerizing one or more members selected from acrylic acid, methacrylic acid, acrylic acid esters, and methacrylic acid esters, and containing 50% by mass or more of structural units selected from structural units derived from acrylic acid, structural units derived from methacrylic acid, structural units derived from acrylic acid esters, and structural units derived from methacrylic acid esters. Examples of acrylic resins include homopolymers of acrylic acid, methacrylic acid, acrylic esters, methacrylic esters, copolymers of acrylic acid and other monomers (e.g., acrylic esters, methacrylic acid, methacrylic esters, α-olefins (e.g., ethylene, divinylbenzene, etc.)), copolymers of methacrylic acid and other monomers (e.g., acrylic acid, acrylic esters, methacrylic esters, α-olefins (e.g., ethylene, divinylbenzene, etc.)), copolymers of acrylic esters and other monomers (e.g., acrylic acid, methacrylic acid, methacrylic esters, α-olefins (e.g., ethylene, divinylbenzene, etc.)), and copolymers of methacrylic esters and other monomers (e.g., acrylic acid, acrylic esters, methacrylic acid, α-olefins (e.g., ethylene, divinylbenzene, etc.)). Among these, methacrylic acid-divinylbenzene copolymers and acrylic acid-divinylbenzene copolymers are preferred.

[0018] The acrylic acid ester is preferably an alkyl acrylate, more preferably a linear or branched alkyl ester of acrylic acid, and even more preferably a linear alkyl ester of acrylic acid. The alkyl group contained in the alkyl ester moiety preferably has 1 to 4 carbon atoms, and the acrylic acid ester is particularly preferably methyl acrylate or ethyl acrylate. The methacrylic acid ester is preferably a methacrylic acid alkyl ester, more preferably a linear or branched alkyl ester of methacrylic acid, and even more preferably a linear alkyl ester of methacrylic acid. The alkyl group contained in the alkyl ester moiety preferably has 1 to 4 carbon atoms, and the methacrylic acid alkyl ester is particularly preferably methyl methacrylate or ethyl methacrylate.

[0019] The matrix of the cation exchange resin may be either a transparent gel type having small pores, a macrolitercular type (MR type) having large macropores, or a macroporous type (also called a porous type or a high-porous type). However, from the viewpoint of metal removal performance, it is preferable that the cation exchange resin have a gel type matrix.

[0020] Examples of cation exchangers include strongly acidic cation exchangers having sulfonic acid groups and weakly acidic cation exchangers having carboxylic acid groups. Examples of H-type cation exchange resins include Amberlite® IRN99H (a gel-type strongly acidic cation exchange resin, trade name, manufactured by DuPont), Amberjet® 1060H (a gel-type strongly acidic cation exchange resin, trade name, manufactured by Organo Corporation), Orlite® DS-1 (a gel-type strongly acidic cation exchange resin, trade name, manufactured by Organo Corporation), and Orlite® DS-4 (a macroporous strongly acidic cation exchange resin, trade name, manufactured by Organo Corporation). One or more H-type cation exchangers may be used alone or in combination. From the viewpoint of metal removal performance, the H-type cation exchanger is preferably a strongly acidic cation exchange resin, more preferably a strongly acidic cation exchange resin having a gel-type matrix.

[0021] When the H-type cation exchanger (C1) used in the present invention is a granular cation exchange resin, the average particle size of the cation exchange resin is not particularly limited and can be, for example, 0.1 to 1.0 mm. Using a resin with a large specific surface area and small particle size as the cation exchange resin increases ion exchange efficiency and further improves metal removal performance. In particular, highly reactive hydrogen peroxide solution is often passed through the resin at low temperatures, which may result in lower diffusivity of metal impurity ions compared to room temperature or heated liquids. Therefore, from the perspective of metal removal performance, it is effective to use a resin with a large specific surface area and small particle size. Specifically, the effects of using a resin with a small particle size are easily achieved when the average particle size of the cation exchange resin is preferably 0.1 to 0.4 mm, more preferably 0.2 to 0.4 mm. The use of a resin with a small particle size is advantageous not only in improving the metal impurity removal efficiency but also in reducing the amount of chemical solution used during resin regeneration, increasing the flow rate during hydrogen peroxide purification, and enabling the ion exchanger container to be made more compact during purification. In this specification, the average particle size means the harmonic mean diameter.

[0022] Hydrogen peroxide is also used as an oxidizing agent and is a chemical that easily deteriorates the matrix of ion exchange resins. Furthermore, when used ion exchange resins are regenerated and reused, the resins are prone to deterioration due to swelling and shrinkage. Therefore, to prevent resin deterioration during repeated use, it is preferable to use a highly cross-linked resin as a cation exchange resin. Highly cross-linked resins are characterized by a large exchange capacity due to the large number of functional groups introduced into the cross-linked moieties. Specifically, for purifying hydrogen peroxide, a strongly acidic cation exchange resin with an exchange capacity of 1.6 eq / L or more is preferably used. Such highly cross-linked cation exchange resins have sufficient chemical resistance and exchange capacity, thereby suppressing resin deterioration even during repeated use and enabling efficient purification of hydrogen peroxide. The exchange capacity (eq / L) is generally expressed as the number of functional groups per volume of the ion exchange resin in equivalents. For example, it can be calculated by completely converting the ion form to the regenerated form (H or OH), contacting the resin with an aqueous solution containing ions that are more selective than H or OH, and measuring the H or OH ions released during ion exchange by titration or other methods. The degree of crosslinking of a resin also correlates with its water retention capacity. Here, the water retention capacity (%) can be calculated from the mass of a saturated resin obtained by exposing the resin to air at 25°C and 100% relative humidity for 30 minutes or more and the mass of the dried resin obtained by drying the saturated resin in a thermostatic oven at 105°C for 16 hours. That is, the water retention capacity (%) can be calculated using the formula: ((mass of saturated ion exchange resin before drying - mass of dried ion exchange resin) / mass of saturated ion exchange resin before drying) × 100. Specifically, a high water retention capacity means that there are many gaps in the resin sufficient to retain water. In other words, a resin with a high water retention capacity tends to have a low degree of crosslinking. In the present invention, from the viewpoint of suppressing deterioration of the resin during repeated use, the water retention capacity of the cation exchange resin is preferably 60% or less. As described below, the mixed-bed ion exchanger (MB2) according to the present invention is suitable for use as a polisher. Since polishers are usually disposable and not reused, resin deterioration does not need to be considered.Therefore, when the mixed-bed ion exchanger (MB2) of the present invention is used as a polisher, the degree of cross-linking (exchange capacity and water retention capacity) of the cation exchange resin in the mixed-bed ion exchanger is not an issue. Furthermore, as mentioned above, small particle size cation exchange resins are preferably used from the viewpoint of the performance in removing metal impurities. However, when the mixed-bed ion exchanger (MB2) of the present invention containing small particle size cation exchange resins is used as a polisher, the small particle size cation exchange resins may be low-cross-linked or high-cross-linked. In other words, there are no restrictions on the exchange capacity or water retention capacity of the small particle size cation exchange resins.

[0023] In the present invention, the H-form cation exchanger before purification, which is subjected to the cation exchanger preparation step, is referred to as H-form cation exchanger (C1), and the H-form cation exchanger after purification in the cation exchanger preparation step is referred to as H-form cation exchanger (C2).

[0024] In the cation exchanger preparation process, as described in Patent Document 4, the H-form cation exchanger (C1) is contacted with a mineral acid solution containing 1 mg / L or less of metal impurities and having a concentration (by mass) of 5% or more to remove or reduce the metal impurities contained in the H-form cation exchanger (C1), thereby obtaining a purified H-form cation exchanger (C2). This allows for the production of an H-form cation exchanger (C2) in which the total amount of metal impurities eluted when 3% (by mass) hydrochloric acid is passed through the H-form cation exchanger at a volume ratio of 25 times the volume of the H-form cation exchanger (C2) is 5 mg / L or less, preferably 3 mg / L or less. To improve analytical accuracy, the amount of metal impurities contained in the 3% (by mass) hydrochloric acid is preferably 1 mg / L or less, although this is not limitative. By contacting the H-form cation exchanger (C1) with a mineral acid solution containing extremely low amounts of metal impurities, the amount of metal impurities contained in the cation exchanger can be reliably and effectively reduced, resulting in an H-form cation exchanger (C2) with low amounts of eluted metal impurities. The mixed-bed ion exchanger (MB2) containing the purified H-form cation exchanger (C2) is then used to purify the hydrogen peroxide solution to be treated, thereby obtaining a highly purified hydrogen peroxide solution containing a small amount of metal impurities. After contacting the H-form cation exchanger (C1) with the mineral acid solution, it is preferable to wash the mineral acid solution with pure water or ultrapure water to remove it.

[0025] The amount of metal impurities contained in the mineral acid solution used for purification is 1 mg / L or less, preferably 0.5 mg / L or less, and more preferably 0.2 mg / L or less. The concentration of the mineral acid solution is 5% or more, preferably 10% or more. A mineral acid solution with a concentration of less than 5% cannot sufficiently reduce the metal impurities in the ion exchanger. The term "metal impurities" includes metal impurity ions, such as sodium (Na), magnesium (Mg), calcium (Ca), and iron (Fe). The mineral acid solution is preferably an aqueous solution, such as hydrochloric acid, sulfuric acid, or nitric acid. "Bringing the H-form cation exchanger (C1) into contact with the mineral acid solution" refers not only to passing the mineral acid solution through the H-form cation exchanger (C1) but also to immersing the H-form cation exchanger (C1) in the mineral acid solution.

[0026] Regarding the obtained H-form cation exchanger (C2), "25 times the volume ratio" of hydrochloric acid means that a volume of hydrochloric acid (3% concentration) 25 times the volume of the cation exchanger is passed through. The unit " / LR" means "per 1 L of volume of cation exchanger in a water-wet state." The water-wet state refers to a state in which the ion exchanger is immersed in water. The volume in a water-wet state can be measured using a measuring device such as a graduated cylinder. Here, the water-wet ion exchanger can be obtained by contacting the ion exchanger with air at 25°C and 100% relative humidity for 15 minutes or more.

[0027] The contents of sodium (Na), magnesium (Mg), calcium (Ca), and iron (Fe) in the mineral acid solution with a concentration of 5% or more are preferably 200 μg / L or less. By contacting a mineral acid solution with a low content of these metal impurities with an ion exchanger, the contents of Na, Mg, Ca, and Fe in the ion exchanger can be reliably and effectively reduced. Similarly, the contents of sodium (Na), magnesium (Mg), calcium (Ca), and iron (Fe) in the hydrochloric acid with a concentration of 3% are preferably 200 μg / L or less.

[0028] The eluted metal impurities may include one or more metals selected from Na, Mg, Ca, and Fe. By controlling the total elution amount of metal impurities including these metals in the purified H-form cation exchanger (C2) to 5 mg / LR or less, preferably 3 mg / LR or less, the amount of these metal impurities eluted from the H-form cation exchanger (C2) into the treated liquid can be reduced when the mixed-bed ion exchanger (MB2) containing the H-form cation exchanger (C2) is used for purifying the treated liquid.

[0029] [Mixed bed ion exchanger preparation process] In this step, the purified H-form cation exchanger (C2) obtained in the cation exchanger preparation step is mixed with the OH-form anion exchanger (A1) to prepare a mixed-bed ion exchanger (MB1) containing the H-form cation exchanger (C2) and the OH-form anion exchanger (A1). The mixed bed containing the H-form cation exchanger (C2) and the OH-form anion exchanger (A1) includes, for example, (i) a mixed bed consisting of a mixture of the H-form cation exchanger (C2) and the OH-form anion exchanger (A1), and (ii) a double-layered bed containing a layer of the H-form cation exchanger (C2) and a layer of the OH-form anion exchanger (A1).

[0030] (OH type anion exchanger) As the OH-form anion exchanger (A1), an OH-form anion exchange resin or a monolithic anion exchanger can be used. Since the ion exchange resin is granular, resins of different ionicities can be easily mixed. The monolithic ion exchanger can be thinly cut and stacked, or can be chopped and then mixed. Alternatively, the monolithic ion exchanger can be mixed with the ion exchange resin. In the present invention, the OH-form anion exchanger (A1) is preferably an OH-form anion exchange resin.

[0031] The anion exchange resin used in the present invention is not particularly limited, but, like the cation exchange resin, an organic polymer-based anion exchange resin having an organic polymer as a host is preferred. Examples of the host organic polymer include styrene-based resins and acrylic-based resins.

[0032] Examples of anion exchangers include strongly basic type I anion exchangers, which have quaternary ammonium groups as functional groups and the only groups bonded to the nitrogen atoms of the quaternary ammonium groups are alkyl groups; strongly basic type II anion exchangers, which have quaternary ammonium groups as functional groups and the groups bonded to the nitrogen atoms of the quaternary ammonium groups are alkyl and alkanol groups; and weakly basic anion exchangers, which have primary to tertiary amino groups as functional groups. Among these, strongly basic type I anion exchangers are preferred. Examples of OH-type anion exchange resins include Orlite® DS-2 (a gel-type strongly basic anion exchange resin, product name, manufactured by Organo Corporation), DS-6 (an MR-type weakly basic anion exchange resin, product name, manufactured by Organo Corporation), and Diaion® WA30 (a highly porous weakly basic anion exchange resin, product name, manufactured by Mitsubishi Chemical Corporation). The OH-type anion exchangers may be used alone or in combination of two or more.

[0033] When the anion exchanger used in the present invention is a granular anion exchange resin, the average particle size of the anion exchange resin is not particularly limited, but can be, for example, 0.1 to 1.0 mm. As with cation exchange resins, using a resin with a large specific surface area and small particle size as the anion exchange resin increases the ion exchange efficiency and further improves metal removal performance. Therefore, from the perspective of metal removal performance, it is effective to use a resin with a large specific surface area and small particle size. Specifically, when the average particle size of the anion exchange resin is preferably 0.1 to 0.4 mm, more preferably 0.2 to 0.4 mm, the effects of using the above-mentioned small particle size resin are easily obtained. Here, in this specification, the average particle size refers to the harmonic mean diameter.

[0034] In the present invention, as long as the mixed-bed ion exchanger (MB2) for hydrogen peroxide purification (described later) contains less than 1 mg / L of metal impurities and elutes less than 3 mg / L of total metal impurities when 25 volumes of 3% hydrochloric acid are passed through it, the OH-form anion exchanger does not need to be purified using a mineral acid solution, as is the case with the H-form cation exchanger. However, if necessary, the OH-form anion exchanger may be purified by a known method so that the metal impurity content of the mixed-bed ion exchanger (MB2) for hydrogen peroxide purification falls within the above-specified range. When purifying the OH-form anion exchanger using a mineral acid solution, a post-purification step of passing a sodium hydroxide solution or potassium hydroxide solution through the anion exchanger is required to regenerate it to the OH-form. Furthermore, due to concerns about metal contamination during this process, sufficient measures to prevent metal contamination are required. Commercially available purified products can also be used as the OH-form anion exchanger. Commercially available purified products, consisting of a mixed bed of OH-form anion exchanger and H-form cation exchanger, may also be used. Commercially available purified products include, for example, the Allite DS series (trade name, manufactured by Organo Corporation), the Amberlite series (trade name, manufactured by Organo Corporation), the Diaion series (trade name, manufactured by Mitsubishi Chemical Corporation), the UltraClean series, the NRW series (all trade names, manufactured by Purolite Co., Ltd.), and the Muromac HG series (trade name, manufactured by Muromachi Chemical Co., Ltd.).

[0035] [Anion exchanger conversion process] When hydrogen peroxide is purified using a basic anion exchanger (OH-form anion exchanger (A1)), decomposition of hydrogen peroxide occurs during contact with the OH-form anion exchanger (A1). Therefore, in the present invention, a mixed-bed ion exchanger (MB2) containing an H-form cation exchanger (C2) and an anion exchanger (A2) is used for the purification of hydrogen peroxide. The OH-form anion exchanger (A1) in the mixed-bed ion exchanger (MB1) is converted to a bicarbonate-form or bicarbonate- and carbonate-form anion exchanger (A2). Specifically, in this step, a mixed-bed ion exchanger (MB1) containing the H-form cation exchanger (C2) and the OH-form anion exchanger (A1) is contacted with dissolved carbon dioxide to convert the OH-form anion exchanger (A1) to a bicarbonate-form anion exchanger or to a bicarbonate-form and carbonate-form anion exchanger (A2) (anion exchanger (A2)), thereby obtaining a mixed-bed ion exchanger (MB2) for hydrogen peroxide purification. After mixing the purified H-form cation exchanger (C2) and the OH-form anion exchanger (A1) to form a mixed bed, the anion exchanger's ion form is converted to the bicarbonate-form (and carbonate-form) using dissolved carbon dioxide, which is highly effective in preventing cross-contamination between ion exchangers.

[0036] As described above, the present invention involves mixing the purified cation exchanger (C2) with the OH-form anion exchanger (A1), converting the ion form of the anion exchanger (A1), and using the resulting mixed-bed ion exchanger (MB2) for the purification of aqueous hydrogen peroxide. However, for example, after optionally subjecting the OH-form anion exchanger to metal reduction treatment, the OH-form anion exchanger may be used as a single bed and converted to the bicarbonate ion form (and carbonate ion form) using carbon dioxide dissolved in water. The cation exchanger (C2) and the bicarbonate ion form (and carbonate ion form) anion exchanger (A2) may then be mixed. The mixed-bed ion exchanger thus obtained can also be suitably used for the purification of aqueous hydrogen peroxide, similar to the mixed-bed ion exchanger (MB2) of the present invention. However, in this case, sufficient measures to prevent metal contamination and quality control are required when mixing the ion exchangers. Alternatively, a step of contacting the OH-form anion exchanger with C2 or A2 may be added before the MB2. That is, if the impurities to be reduced contained in the hydrogen peroxide solution to be purified contain a large amount of cationic components, then providing C2 in the upstream stage, or if the impurities to be reduced contain a large amount of anionic components, then providing A2 in the upstream stage will enable more efficient reduction of ionic impurities. On the other hand, if the amount of cationic components is significantly low, then hydrogen peroxide solution may be purified using only A2, and if the amount of anionic components is significantly low, then hydrogen peroxide solution may be purified using only C2. In this way, optimization can be performed appropriately depending on the composition of the ionic impurities to be reduced.

[0037] (carbon dioxide dissolved in water) The carbon dioxide-dissolved water used in the anion exchanger conversion step is obtained by dissolving carbon dioxide gas in pure water or ultrapure water. The pure water or ultrapure water is obtained by treating raw water using a water purification system or ultrapure water purification system that removes ions and nonionic substances from the raw water. Specifically, pure water with a resistivity of 1.0 MΩ·cm or higher is preferred, ultrapure water with a resistivity of 10 MΩ·cm or higher is more preferred, and ultrapure water with a resistivity of 18 MΩ·cm or higher is even more preferred. The concentration of carbon dioxide dissolved in the carbon dioxide-dissolved water is not particularly limited as long as it is a concentration at which carbon dioxide gas can be dissolved in pure water or ultrapure water, but is preferably 1 to 2000 mg / L, more preferably 20 to 2000 mg / L. The higher the concentration of carbon dioxide dissolved, the shorter the treatment time and the less water is used.

[0038] The method for obtaining carbon dioxide-dissolved water, i.e., the method for dissolving carbon dioxide gas in pure water or ultrapure water, is not particularly limited, and examples include the production of functional water used for cleaning electronic components. Examples include dissolving carbon dioxide gas using a hollow fiber membrane, bubbling carbon dioxide gas directly into a pipe, dissolving carbon dioxide gas after injecting it using a dispersion device such as a static mixer, and dissolving carbon dioxide gas by stirring within the pump upstream of a pump that supplies ultrapure water to a gas dissolution tank. Dissolving carbon dioxide gas using a hollow fiber membrane is preferred for efficient dissolution of carbon dioxide to its saturated concentration. When using a gas cylinder to supply carbon dioxide gas, a particle removal filter for removing particles of 0.5 μm or less is preferably installed in the gas supply pipe, and a particle removal filter for removing particles of 0.2 μm or less is more preferred. In preparing carbon dioxide-dissolved water, the amount of carbon dioxide gas dissolved in pure water or ultrapure water is controlled by a gas mass flow controller. Furthermore, the carbon dioxide concentration is continuously monitored using a conductivity meter.

[0039] The lower the temperature at which carbon dioxide-dissolved water is brought into contact with the mixed-bed ion exchanger (MB1), the higher the solubility of carbon dioxide, and therefore the more preferable. However, from the viewpoint of energy consumption, the temperature is preferably 5 to 40°C, more preferably 10 to 30°C. When carbon dioxide-dissolved water is passed through an ion exchange tower packed with a mixed-bed ion exchanger (MB1), the carbon dioxide-dissolved water may be supplied to the ion exchange tower in a single pass. However, to reduce the amount of pure water or ultrapure water used, a circulation tank and pump can be installed downstream of the ion exchange tower, and the used water can be recycled and reused as raw water for preparing carbon dioxide-dissolved water. When the water used is recycled, the amount of carbon dioxide supplied can be reduced by controlling the amount of carbon dioxide supplied using feedback from a conductivity meter.

[0040] By carrying out the anion exchanger conversion step, all or part of the counter anions of the OH-form anion exchanger (A1) in the mixed-bed ion exchanger (MB1) containing the H-form cation exchanger (C2) and the OH-form anion exchanger (A1) are exchanged for bicarbonate ions (-HCO3) or carbonate ions (-CO3), thereby obtaining a mixed-bed ion exchanger for hydrogen peroxide purification containing a bicarbonate ion-form anion exchanger, or a mixed-bed ion exchanger for hydrogen peroxide purification containing a bicarbonate ion-form anion exchanger and a carbonate ion-form anion exchanger (MB2).

[0041] The anion exchanger (A2) obtained after the anion exchanger conversion step is an anion exchanger having a bicarbonate ion form (-HCO3), or an anion exchanger having both a bicarbonate ion form (-HCO3) and a carbonate ion form (-CO3), i.e., an anion exchanger having an anion exchange group whose counter anion is a bicarbonate ion (-HCO3 ion), or an anion exchanger having an anion exchange group whose counter anion is a bicarbonate ion (-HCO3 ion) and an anion exchange group whose counter anion is a carbonate ion (-CO3 ion). Note that although the terms bicarbonate ion form (R-HCO3) and carbonate ion form (R-CO3) are used in this specification, in actual use, the bicarbonate ion form is R-HCO3. -and the carbonate ion form is R-CO3 2- and is dissociated.

[0042] In the anion exchanger (A2) obtained after the anion exchanger conversion step, the ratio of the total exchange capacity of the bicarbonate ion and carbonate ion forms to the total exchange capacity of the anion exchanger is not particularly limited. However, the greater the number of anion exchange groups converted to bicarbonate ion or carbonate ion form among all the anion exchange groups present in the anion exchanger, the higher the performance. Therefore, in the anion exchanger (A2), the ratio of the total exchange capacity of the bicarbonate ion and carbonate ion forms to the total exchange capacity of the anion exchanger is preferably 50 equivalent% or more, more preferably 60 equivalent% or more, even more preferably 70 equivalent% or more, even more preferably 80 equivalent% or more, even more preferably 95 equivalent% or more, even more preferably 99 equivalent% or more, and particularly preferably 100 equivalent%. That is, in the anion exchanger conversion step, it is preferable to bring the mixed-bed ion exchanger (MB1) containing the H-form cation exchanger (C2) and the OH-form anion exchanger (A1) into contact with water containing dissolved carbon dioxide until the ratio of the sum of the exchange capacities of the bicarbonate ion type and the carbonate ion type to the total exchange capacity of the anion exchanger reaches the above-mentioned preferred value.

[0043] In the anion exchanger (A2) obtained after the anion exchanger conversion step, the ratio of the exchange capacity of the bicarbonate ion form to the total exchange capacity of the bicarbonate ion form and the carbonate ion form is preferably 70 equivalent % or more, more preferably 75 equivalent % or more, and even more preferably 80 equivalent % or more. The bicarbonate ion form has a lower selectivity coefficient than the carbonate ion form, and is therefore effective in improving treatment performance, particularly for anions with low selectivity and low ion exchange load concentrations. Therefore, the higher the proportion of the bicarbonate ion form in the anion exchanger (A2), the higher the purification performance of aqueous hydrogen peroxide.

[0044] In the anion exchanger conversion step, for example, a mixed-bed ion exchanger (MB1) containing an H-form cation exchanger (C2) and an OH-form anion exchanger (A1) is placed in a container equipped with a supply pipe and a discharge pipe for carbon dioxide-dissolved water, and the carbon dioxide-dissolved water is continuously contacted with the mixed-bed ion exchanger (MB1) by supplying the carbon dioxide-dissolved water into the container while discharging the water from the container. The conductivity of the carbon dioxide-dissolved water before and after contact with the mixed-bed ion exchanger (MB1) is measured using a conductivity meter attached to each of the supply pipe and the discharge pipe. The carbon dioxide-dissolved water is contacted until the ratio of the conductivity of the carbon dioxide-dissolved water after contact with the mixed-bed ion exchanger (MB1) to the conductivity of the carbon dioxide-dissolved water before contact ((conductivity after contact / conductivity before contact) × 100)) is preferably 90% or more, more preferably 95% or more. By contacting the mixed-bed ion exchanger (MB1) with the carbon dioxide-dissolved water while measuring the ratio of the conductivity of the carbon dioxide-dissolved water before and after contact with the mixed-bed ion exchanger (MB1), it becomes easier to determine the end point of the anion exchanger conversion process.

[0045] In the anion exchange conversion process, after the mixed-bed ion exchanger (MB1) is contacted with the dissolved carbon dioxide, most of the carbon dioxide (bicarbonate ions or carbonate ions produced by dissolving carbon dioxide in water) is consumed for ion exchange to the bicarbonate or carbonate form of the OH-form anion exchanger for a while. This results in a very low concentration of bicarbonate or carbonate ions in the dissolved carbon dioxide. As a result, the conductivity of the dissolved carbon dioxide after contact with the mixed-bed ion exchanger is very low for a while. As the ion exchange to the bicarbonate or carbonate form continues and the number of anion exchange groups in the anion exchanger increases, the amount of carbon dioxide consumed for ion exchange to the bicarbonate or carbonate form gradually decreases. Therefore, the concentration of bicarbonate or carbonate ions in the dissolved carbon dioxide after contact with the mixed-bed ion exchanger gradually increases, and the conductivity of the dissolved carbon dioxide after contact with the mixed-bed ion exchanger gradually increases. When the ratio of the conductivity of the dissolved carbon dioxide water after contact with the mixed-bed ion exchanger (MB1) to the conductivity of the dissolved carbon dioxide water before contact with the mixed-bed ion exchanger (MB1) ((conductivity after contact / conductivity before contact) × 100)) falls within the above range, it can be determined that most of the anion exchange groups in the anion exchanger (A1) have been converted to bicarbonate or carbonate ions, i.e., anion exchanger (A2) has been obtained. In the present invention, the conductivity of the dissolved carbon dioxide water before contact with the mixed-bed ion exchanger (MB1) in the anion exchanger conversion step is determined as the conductivity of the dissolved carbon dioxide water before contact with the mixed-bed ion exchanger (MB1) in the anion exchanger conversion step, when the conductivity becomes almost constant after contacting the dissolved carbon dioxide water with the mixed-bed ion exchanger (MB1) for a certain period of time.

[0046] Here, the exchange capacity of the anion exchange groups that are not in the bicarbonate or carbonate form among all the anion exchange groups in the anion exchanger (A2) before contact with the carbon dioxide-dissolved water can be determined by analyzing the anion exchanger before contact. Therefore, it is possible to calculate the required amount of carbon dioxide to be supplied assuming that all of the supplied carbon dioxide is used for ion exchange. However, in reality, not all of the supplied carbon dioxide is used for ion exchange. Therefore, when converting the anion exchange groups, a significant excess of carbon dioxide-dissolved water must be supplied to ensure the conversion of the anion exchange groups. However, as described above, by measuring the conductivity of the carbon dioxide-dissolved water before and after contact with the mixed-bed ion exchanger (MB1) and observing the transition in the conductivity ratio, it is possible to determine the point at which the ratio of the sum of the exchange capacities of the bicarbonate and carbonate forms to the total exchange capacity of the anion exchange groups in the anion exchanger reaches the above-mentioned preferred range (e.g., 80 equivalent % or more, 95 equivalent % or more). If a large number of OH groups remain in the OH-form anion exchanger (A1), hydrogen peroxide may be decomposed during purification, possibly resulting in an increase in internal pressure. Therefore, it is preferable that the proportion of OH groups in the anion exchanger is low.

[0047] According to the above method, carbon dioxide-dissolved water is used instead of a carbonate or bicarbonate aqueous solution to convert the OH groups in the OH-form anion exchanger (A1) to the bicarbonate or carbonate ion form. Therefore, hydrogen ions in the H-form cation exchanger present with the anion exchanger are not exchanged with carbonate or bicarbonate cations. This method is efficient because it allows the ion form of the anion exchanger to be converted in the mixed bed state with the cation exchanger. Furthermore, the carbon dioxide-dissolved water used for ion form conversion is obtained by dissolving carbon dioxide gas in pure water or ultrapure water, and therefore contains very little metal. Therefore, the above method is also advantageous in that it can suppress contamination with metal impurities during this process.

[0048] The mixed-bed ion exchanger (MB2) for hydrogen peroxide purification, which contains the H-form cation exchanger (C2) and the bicarbonate-form or bicarbonate- and carbonate-form anion exchanger (A2) obtained after the anion exchanger conversion step, contains no more than 1 mg / L of metal impurities and elutes no more than 3 mg / L of total metal impurities when 25 volumes of 3% hydrochloric acid are passed through it. The amount of metal impurities can be measured, for example, using an inductively coupled plasma mass spectrometry (ICP-MS).

[0049] [Control of metal impurity content] As mentioned above, the amount of metal impurities contained in a mixed-bed ion exchanger (MB2) for hydrogen peroxide purification is determined by measuring the total amount of metal impurities eluted when a 25-fold volume of hydrochloric acid containing 3% (by mass) hydrochloric acid with a metal impurity content of 1 mg / L or less is passed through the mixed-bed ion exchanger (see Patent Document 4). By using this method to determine and control the amount of metal impurities contained in the mixed-bed ion exchanger (MB2) for hydrogen peroxide purification, a mixed-bed ion exchanger capable of stable high-purity purification can be provided.

[0050] When analyzing a sample of a mixed-bed ion exchanger (MB2) containing an H-form cation exchanger (C2) and an anion exchanger (A2) in bicarbonate or bicarbonate and carbonate forms, the carbonate and bicarbonate ions exchange with Cl ions in hydrochloric acid, generating bubbles in the hydrochloric acid. Therefore, when hydrochloric acid is passed through a column, the bubbles trapped in the column can cause short-path flow during hydrochloric acid flow. This can lead to the hydrochloric acid passing through the column without passing through the resin, potentially preventing efficient elution of metals from the resin into the hydrochloric acid. This makes it difficult to accurately measure the amount of metal impurities contained in the mixed-bed ion exchanger. Therefore, it is preferable to control the amount of metal impurities contained in the mixed-bed ion exchanger (MB2) using the above method before converting the anion exchanger's ion form to the bicarbonate (and carbonate) form by passing carbon dioxide-dissolved water through the column. However, even after passing carbon dioxide-dissolved water through the anion exchanger, analytical control is possible even after the ion form of the anion exchanger is converted if the contact with hydrochloric acid is carried out in a batchwise manner, in which the generation of bubbles is not a problem. However, in this case, the contact with hydrochloric acid in a batchwise manner must be carried out in an open state.

[0051] As mentioned above, the carbon dioxide-dissolved water used for ionic form conversion is obtained by dissolving carbon dioxide gas in pure water or ultrapure water, and the metal impurity concentration in the carbon dioxide-dissolved water can be maintained at a low level comparable to that of ultrapure water. Therefore, the possibility of metal impurities being mixed in during the anion exchanger conversion process is extremely low. Therefore, a mixed-bed ion exchanger (MB1) that is controlled so that "it contains 1 mg / L or less of metal impurities and the total amount of metal impurities eluted when 25 volumes of 3% (by mass) hydrochloric acid are passed through it" before converting the anion exchanger's ionic form to bicarbonate ion (and carbonate ion) ion form still satisfies the requirement of "it contains 1 mg / L or less of metal impurities and the total amount of metal impurities eluted when 25 volumes of 3% (by mass) hydrochloric acid are passed through it" even after the anion exchanger's ionic form conversion.

[0052] As described above, in the present invention, it is preferable to control the amount of metal impurities contained in the mixed-bed ion exchanger (MB2) for hydrogen peroxide purification before converting the ionic form of the anion exchanger. That is, if the mixed-bed ion exchanger (MB1) contains "less than 1 mg / L of metal impurities and the total amount of metal impurities eluted when 25 volumes of 3% (by mass) hydrochloric acid are passed through it" then it can be determined that the mixed-bed ion exchanger (MB2) for hydrogen peroxide purification after ionic form conversion of the anion exchanger contains "less than 1 mg / L of metal impurities and the total amount of metal impurities eluted when 25 volumes of 3% (by mass) hydrochloric acid are passed through it"

[0053] <Method for purifying hydrogen peroxide> The method for purifying hydrogen peroxide solution according to the present invention is characterized by using a mixed-bed ion exchanger (MB2) for purifying hydrogen peroxide solution prepared by the above-described preparation method according to the present invention. By performing purification using a mixed-bed ion exchanger with reduced metal impurities, it is possible to obtain hydrogen peroxide solution of extremely high purity.

[0054] [Hydrogen peroxide] In the present invention, the hydrogen peroxide solution to be purified (also referred to as "crude hydrogen peroxide solution") can be industrially produced by the anthraquinone method or the like. However, hydrogen peroxide solution of higher purity can be obtained by crudely purifying industrial hydrogen peroxide solution using an ion exchange resin or reverse osmosis process. The concentration of hydrogen peroxide solution to be treated is not particularly limited, but is usually 1 to 65% by mass, preferably 1 to 40% by mass.

[0055] Examples of metal components that are impurities contained in hydrogen peroxide solution include aluminum, calcium, chromium, iron, potassium, magnesium, manganese, molybdenum, sodium, nickel, tin, titanium, silver, barium, beryllium, bismuth, cadmium, cobalt, copper, gallium, lithium, lead, antimony, strontium, thallium, vanadium, zinc, zirconium, arsenic, etc. Metal components other than those listed above may also be contained.

[0056] The metal concentrations in crude hydrogen peroxide solution are not particularly limited, but in the case of hydrogen peroxide solution roughly purified using a reverse osmosis membrane, the metal concentrations are about 1 to 100 ppt by mass, and in the case of industrial hydrogen peroxide solution, the sodium concentration is about 10 ppm by mass, and other metals may be present in amounts up to several hundred ppb by mass. The present invention is applicable to both crude hydrogen peroxide solutions.

[0057] The method for purifying hydrogen peroxide according to the present invention includes a step of contacting hydrogen peroxide with an ion exchanger, and the ion exchanger used is the mixed-bed ion exchanger (MB2) for hydrogen peroxide purification obtained by the preparation method according to the present invention. Specifically, the crude hydrogen peroxide can be purified by passing it through an ion exchange column packed with the mixed-bed ion exchanger (MB2) for hydrogen peroxide purification and contacting the crude hydrogen peroxide with the mixed-bed ion exchanger (MB2). Alternatively, the hydrogen peroxide may be contacted with the mixed-bed ion exchanger (MB2) in a batchwise manner.

[0058] The temperature when crude hydrogen peroxide solution is brought into contact with the mixed bed ion exchanger (MB2) for hydrogen peroxide solution purification is preferably −10 to 25° C., more preferably −5 to 20° C., from the viewpoint of suppressing decomposition of hydrogen peroxide solution. In addition, in the purification of hydrogen peroxide solution, the space velocity (SV) of crude hydrogen peroxide solution passed through the ion exchange column is not particularly limited, but is preferably 1 to 30 h -1 , more preferably 1 to 15 hours -1 Other liquid passing conditions are not particularly limited, and general methods can be used with appropriate adjustments.

[0059] [Use as a polisher] When purifying hydrogen peroxide solution, it is possible to combine known hydrogen peroxide solution purification methods with the hydrogen peroxide solution purification method of the present invention. That is, in a preferred embodiment of the present invention, a mixed-bed ion exchanger (MB2) for hydrogen peroxide solution purification prepared by the preparation method of the present invention is used as a polisher for hydrogen peroxide solution after it has been subjected to a purification treatment using a combination of two or more selected from the group consisting of an adsorbent, an ion exchange resin, and a particulate removal filter. Known synthetic adsorbents capable of adsorbing and removing organic impurities can be used as adsorbents. Examples of such adsorbents include Amberlite XAD (trade name, manufactured by Organo Corporation), Diaion HP series, Sepabeads SP800 series, Sepabeads SP70, Sepabeads SP700, Sepabeads SP207, Diaion HP2MGL, and small particle size synthetic adsorbents such as Diaion HP20SS, Sepabeads SP20SS, and Sepabeads 207SS (all trade names, manufactured by Mitsubishi Chemical Corporation). The ion exchange resin can be a combination of an anion exchange resin, which is a typical ion exchange resin used in pure water production, converted into carbonate form, and a cation exchange resin. The particulate removal filter is typically a membrane filter. However, an ion adsorption membrane having functional groups or a combination of an ion adsorption membrane and a membrane filter may also be used. After the concentration of each metal impurity in the hydrogen peroxide solution has been reduced to approximately 1 ppb to single-digit ppt through a purification process that combines two or more of these, it is preferable to use the mixed bed ion exchanger (MB2) for hydrogen peroxide solution purification prepared using the present invention as a finishing polisher to further reduce the amount of metal impurities.

[0060] The mixed-bed ion exchanger (MB2) for hydrogen peroxide purification used as a polisher is preferably stored in a container made of a fluororesin or a container with an inner surface coated with a fluororesin, which reduces metal elution, as needed, until it is used for purification. These containers may be column-shaped, or may be cylinder- or cartridge-type containers that can be replaced individually. Once used as a polisher, the mixed-bed ion exchanger is usually discarded without being regenerated.

[0061] [Application of ammonium bicarbonate as a purification resin] The mixed-bed ion exchanger (MB2) for hydrogen peroxide purification according to the present invention is primarily used for purifying hydrogen peroxide, but it can also be used for purifying ammonium bicarbonate. Generally, carbonate- or bicarbonate-form anion exchange resins are prepared by passing an ammonium bicarbonate solution through an OH-form anion exchange resin. It is preferable to sufficiently reduce the amount of metal impurities in the ammonium bicarbonate solution used in this process. This is because if metal impurities exist in anionic form, such as oxides or complex ions, in the ammonium bicarbonate solution, these anionic metal impurities may become a source of contamination for the anion exchange resin during ion-form conversion. Therefore, by using the mixed-bed ion exchanger (MB2) according to the present invention, prepared using carbon dioxide-dissolved water, to purify the ammonium bicarbonate solution used for ion-form conversion, changes in the carbonate and bicarbonate concentrations and pH in the solution can be suppressed, and the amount of anionic metal impurities contained in the ammonium bicarbonate solution can be reduced without leaching of metal impurities from the mixed-bed ion exchanger. As the ammonium bicarbonate solution, an ammonium bicarbonate solution that is usually used for preparing an anion exchange resin of carbonate ion type or bicarbonate ion type can be used.

[0062] [Application as a solution for creating a calibration curve] Hydrogen peroxide purified using the hydrogen peroxide purification method of the present invention can be used as a calibration curve preparation solution when measuring the amount of metal impurities contained in high-purity hydrogen peroxide using ICP-MS. It is known that in ICP-MS measurements, reducing the impurities in the calibration curve preparation solution allows for the measurement of lower concentrations of the analyte in the sample solution and improves analytical accuracy. In particular, the calibration curve preparation solution is required to have the same liquid properties (type and concentration of chemical solution) as the sample solution and to have a sufficiently low concentration of the analyte metal. Therefore, when hydrogen peroxide purified by the method of the present invention is used as the sample solution, using the high-purity hydrogen peroxide obtained by the hydrogen peroxide purification method of the present invention as the calibration curve preparation solution enables efficient and highly accurate analysis.

[0063] [Regeneration of mixed-bed ion exchangers] When a liquid to be treated (e.g., hydrogen peroxide solution) is purified using a mixed-bed ion exchanger (MB2) containing an H-form cation exchanger (C2) and an anion exchanger (A2) in the bicarbonate ion form or in the bicarbonate and carbonate ion forms, the bicarbonate ions in the anion exchanger (A2) contained in the mixed-bed ion exchanger are exchanged for impurity anions in the liquid to be treated. Therefore, after continuing to purify the liquid to a certain extent, it is necessary to regenerate the anion exchanger ion-exchanged with impurity anions back into the bicarbonate ion form or the bicarbonate and carbonate ion forms. The regeneration of the anion exchanger ion-exchanged with impurity anions is achieved by subjecting the anion exchanger to the anion exchanger conversion step. As a regeneration method, a method of contacting a used mixed-bed ion exchanger (MB2) with water containing dissolved carbon dioxide while it is still in the mixed bed or a method of separating a used mixed-bed ion exchanger (MB2) into a cation exchanger and an anion exchanger, converting the ions into H-type cation exchanger and OH-type cation exchanger, and then mixing the two and contacting them with water containing dissolved carbon dioxide may be used. [Example]

[0064] The effects of the present invention will be explained below by way of examples, but these examples are merely illustrative and do not limit the present invention.

[0065] [Example 1, Comparative Example 1] (Mixed bed ion exchanger preparation process) The following cation exchange resins and anion exchange resins were prepared as ion exchangers. A mixed bed of Mix A and Mix B (mixed-bed ion exchanger (MB1)) was prepared in the following combination. Mix A contained metal impurities of 1 mg / L or less, and when 3% hydrochloric acid was passed through the mixed bed at a volume ratio of 25 times, the total amount of metal impurities eluted was more than 3 mg / L. Mix B contained the total amount of metal impurities of 3 mg / L or less. [resin] Cation exchange resin A: A styrene resin, gel-type, strongly acidic cation exchange resin purified using special-grade hydrochloric acid (metal impurity content: more than 1 mg / L, concentration: 36%). The metal impurity content is 1 mg / L or less, and when 25 volumes of 3% hydrochloric acid are passed through, the total amount of metal impurities eluted is more than 5 mg / L. Cation exchange resin B: A styrene-based resin, gel-type, strongly acidic cation exchange resin purified using high-purity hydrochloric acid (metal impurity content: 1 mg / L or less, concentration: 36%). The metal impurity content is 1 mg / L or less, and when 25 times the volume of 3% hydrochloric acid is passed through, the total amount of metal impurities eluted is 3 mg / L or less. Anion exchange resin C: A strong anion exchange resin made of styrene-based resin, gel type, OH ion type, a highly purified product containing metal impurities of 1 mg / L or less, and the total amount of metal impurities eluted when 25 times the volume of 3% hydrochloric acid is passed through it is 3 mg / L or less. [Mixed bed] Mix A (Resin A and Resin C mixed at a volume ratio of 1:1): Comparative Example 1 Mix B (Resin B and Resin C mixed at a volume ratio of 1:1): Example 1

[0066] (Anion exchanger conversion process) This step was carried out in accordance with the method described in Example 1 of Patent Document 3. 36 mL of the prepared mixed bed Mix A and Mix B were each packed into a PFA ion exchange tower (inner diameter: 16 mm, height: 300 mm) equipped with a PFA mesh at the bottom. Next, ultrapure water and carbon dioxide gas were supplied to the gas dissolution hollow fiber membrane using a gas mass flow controller, and the carbon dioxide gas was dissolved in the ultrapure water to obtain carbon dioxide-dissolved water. The obtained carbon dioxide-dissolved water was then supplied into each ion exchange tower, and the carbon dioxide-dissolved water was passed through the mixed bed. During this process, the flow rate through the ion exchange tower was set to 1.5 L / h, and the amount of carbon dioxide gas supplied to the gas dissolution hollow fiber membrane was adjusted so that the conductivity at the tower inlet was 38 μS / cm. The carbon dioxide-dissolved water was then passed through the ion exchange resin until the conductivity at the tower outlet reached the same level as the inlet (38 μS / cm) (approximately 90 minutes). The carbon dioxide-dissolved water was then passed through the ion exchange resin to convert the ion form of the anion exchange resin to bicarbonate ion form (and carbonate ion form). In this manner, a mixed-bed ion exchanger (MB2) for hydrogen peroxide purification was obtained for each of the mixed-bed Mix A and Mix B. The conductivity of the carbon dioxide-dissolved water at the tower inlet fluctuated slightly for a while after the start of the supply of the carbon dioxide-dissolved water to the ion exchange tower, but after approximately 45 minutes had passed, it stabilized at 38 μS / cm.

[0067] The metal contents (mg / L) of Mix A and Mix B (mixed-bed ion exchanger (MB2)) after passing the carbon dioxide-dissolved water were analyzed by ICP-MS (hydrochloric acid elution method), which involves analyzing the total amount of metal impurities eluted when 3% hydrochloric acid containing metal impurities of 1 mg / L or less is passed through the mixed-bed ion exchanger at a volume ratio of 25 times the volume of the eluted metal impurities. The analysis was performed using a column packed with the mixed-bed ion exchanger. Care was taken to prevent air bubbles from forming during the analysis. An Agilent 8900 triple quadrupole ICP-MS (trade name, manufactured by Agilent) was used for the ICP-MS. The analysis results are shown in Table 1. As shown in Table 1, the metal contents of the mixed-bed ion exchanger (Example 1) for Mix B, which contained cation exchange resin B purified with high-purity hydrochloric acid, were found to be lower than those of the mixed-bed ion exchanger (Comparative Example 1) for Mix A.

[0068] [Table 1]

[0069] [Example 2, Comparative Example 2] (purification of hydrogen peroxide solution) A hydrogen peroxide purification test was conducted using each of the mixed bed ion exchangers (MB2) for hydrogen peroxide purification obtained in Example 1 and Comparative Example 1. The hydrogen peroxide to be purified was prepared by adding a general-purpose mixed standard solution (trade name: XSTC-13, manufactured by SPEX) to 35% by mass hydrogen peroxide solution (trade name: TAMAPURE-AA-10, manufactured by Tama Chemicals Co., Ltd.) so that each metal element contained approximately 100 ppt. The treatment conditions for the purification test were as follows: [Processing conditions] Liquid flow rate: 10BV Flow rate: SV5, pump delivery Temperature: All simulation solutions and column treatment solutions should be kept below 16°C.

[0070] The metal contents (ng / L) of the simulated liquid before purification (raw liquid) and the simulated liquid after purification (treated liquid) were measured using an ICP-MS (trade name: Agilent 8900, manufactured by Agilent). The results are shown in Table 2. Note that for the treated liquid, "BV 2.5-5" refers to the average metal content from the point at which 2.5 BV of the treated liquid had passed through to the point at which ~5 BV had passed through (initial period of passing). Similarly, "BV 7.5-10" refers to the average metal content from the point at which 7.5 BV of the treated liquid had passed through to the point at which ~10 BV had passed through.

[0071] [Table 2]

[0072] In Example 2, in which purification was performed using a mixed-bed ion exchanger based on Mix B, which had a reduced metal content, high metal removal performance was observed from the early stage of the run, with particularly remarkable K removal. Comparing Example 2 with Comparative Example 2, in which purification was performed using a mixed-bed ion exchanger based on Mix A, which had no reduced metal content, a significant difference in Fe removal performance was observed at the early stage of the run (BV 2.5 to 5). Thus, according to the present invention, it was found that further improvements in the purity of aqueous hydrogen peroxide can be achieved by reducing the metal content of the ion exchanger itself used for purification. Furthermore, it was confirmed that the use of the mixed-bed ion exchanger for purifying aqueous hydrogen peroxide according to the present invention makes it possible to reduce metal concentrations, particularly at the early stage of the run, and improve start-up. In other words, according to the present invention, it is possible to reduce the amount of treatment solution containing a high amount of metal impurities at the early stage of the run that is discarded, thereby enabling economical and efficient production of highly pure aqueous hydrogen peroxide.

[0073] [Examples 3 to 6] In order to confirm the influence of differences in the matrix and particle size on the metal removal performance from hydrogen peroxide solution, a batch immersion test was carried out as follows using hydrogen peroxide solution containing metal impurities.

[0074] (Mixed bed ion exchanger preparation process) As ion exchangers, the cation exchange resin B, the anion exchange resin C, and the following cation exchange resins and anion exchange resins were prepared. Mixed beds Mix B to Mix E (mixed-bed ion exchangers (MB1)) were prepared in the combinations shown below. Mix B was the same mixed bed as used in Example 1, and the mixed beds Mix B to Mix E contained metal impurities of 1 mg / L or less, and the total amount of metal impurities eluted when 3% hydrochloric acid was passed through them at a volume ratio of 25 times the volume was 3 mg / L or less. The harmonic mean diameter, exchange capacity, and water retention capacity of the cation exchange resin used in each mixed bed are shown in Table 3. [resin] Cation exchange resin D: A styrene-based resin, macroporous, strongly acidic cation exchange resin purified using high-purity hydrochloric acid (metal impurity content: 1 mg / L or less, concentration: 36%). The metal impurity content is 1 mg / L or less, and when 25 volumes of 3% hydrochloric acid are passed through, the total amount of metal impurities eluted is 3 mg / L or less. Cation exchange resin E: A styrene-based resin, gel-type, strongly acidic cation exchange resin purified using high-purity hydrochloric acid (metal impurity content: 1 mg / L or less, concentration: 36%). The metal impurity content is 1 mg / L or less, and when 25 times the volume of 3% hydrochloric acid is passed through, the total amount of metal impurities eluted is 3 mg / L or less. Cation exchange resin F: A styrene-based resin, gel-type, strongly acidic cation exchange resin purified using high-purity hydrochloric acid (metal impurity content: 1 mg / L or less, concentration: 36%). The metal impurity content is 1 mg / L or less, and when 25 volumes of 3% hydrochloric acid are passed through, the total amount of metal impurities eluted is 3 mg / L or less. [Mixed bed] Mix B (Resin B and Resin C mixed at a volume ratio of 1:1): Example 3 Mix C (Resin D and Resin C mixed at a volume ratio of 1:1): Example 4 Mix D (Resin E and Resin C mixed at a volume ratio of 1:1): Example 5 Mix E (Resin F and Resin C mixed at a volume ratio of 1:1): Example 6

[0075] (Anion exchanger conversion process) The mixed beds were subjected to an anion exchanger conversion step in the same manner as in Example 1 to convert the ionic form of the anion exchange resin, thereby obtaining mixed-bed ion exchangers (MB2) according to each Example. The mixed-bed ion exchangers (MB2) obtained according to each Example contained metal impurities in an amount of 1 mg / L or less, and the total amount of metal impurities eluted when 3% hydrochloric acid was passed through them in a volume ratio of 25 times that of the mixed beds was 3 mg / L or less.

[0076] (purification of hydrogen peroxide solution) A hydrogen peroxide purification test was conducted using each of the mixed-bed ion exchangers (MB2). The hydrogen peroxide to be purified was prepared by adding a general-purpose mixed standard solution (product name: XSTC-13, manufactured by SPEX) to 30% by mass hydrogen peroxide (manufactured by Kanto Chemical Co., Inc.) to prepare a simulated solution containing approximately 10 ppb of each metal element. The treatment conditions for the purification test were as follows: After stirring, the metal content (μg / L) in the supernatant was analyzed using an ICP-MS (product name: Agilent 8900, manufactured by Agilent). The metal removal rate (%) for each metal was calculated from the obtained metal content and the metal content in the simulated solution before purification. The results are shown in Table 3 and Figure 1. [Processing conditions] Liquid volume: 5BV, batch immersion Mixing time: 15 minutes or more Temperature: 25℃

[0077] [Table 3]

[0078] As shown in Table 3, the metal removal rates in Examples 3, 5, and 6, in which the matrix of the cation exchange resin contained in the mixed bed was gel-type, were higher than the metal removal rate in Example 4, in which the matrix was macroporous. Therefore, it is preferable that the mixed-bed ion exchanger used in purifying hydrogen peroxide solution contains a gel-type cation exchanger as the cation exchanger. Furthermore, among the gel-type cation exchange resins used in Examples 3, 5, and 6, the cation exchange resins used in Examples 5 and 6 were small particle size products with a harmonic mean diameter of 0.2 to 0.4 mm. The small particle size products exhibited performance equivalent to that of Example 3, which used a cation exchange resin with a general particle size, regardless of differences in water retention capacity and exchange capacity. However, because the small particle size products are characterized by their large surface area, they are advantageous in that they not only improve the efficiency of removing metal impurities, but also reduce the amount of chemical solution used during regeneration, increase the flow rate during purification, and enable the ion exchanger container to be made more compact during purification.

Claims

1. a cation exchanger preparation step of contacting the H-form cation exchanger (C1) with a mineral acid solution containing metal impurities in an amount of 1 mg / L or less and having a concentration of 5% or more to obtain a purified H-form cation exchanger (C2); a mixed-bed ion exchanger preparation step of mixing the H-form cation exchanger (C2) with the OH-form anion exchanger (A1) to prepare a mixed-bed ion exchanger (MB1); an anion exchanger conversion step of converting the OH-form anion exchanger (A1) into a bicarbonate-form or bicarbonate-form and carbonate-form anion exchanger (A2) by contacting the mixed-bed ion exchanger (MB1) with water having dissolved therein carbon dioxide, thereby obtaining a mixed-bed ion exchanger (MB2) for hydrogen peroxide purification; The mixed bed ion exchanger (MB2) for hydrogen peroxide purification is characterized in that the amount of metal impurities contained is 1 mg / L or less, and the total amount of metal impurities eluted when 3% hydrochloric acid is passed through it in a volume ratio of 25 times that of the mixed bed ion exchanger (MB2) is 3 mg / L-R or less.

2. 2. The method for preparing a mixed bed ion exchanger for hydrogen peroxide purification according to claim 1, wherein the metal contents of sodium (Na), magnesium (Mg), calcium (Ca), and iron (Fe) in the mineral acid solution and the hydrochloric acid are each 200 μg / L or less.

3. 3. The method for preparing a mixed bed ion exchanger for hydrogen peroxide purification according to claim 1 or 2, wherein in the anion exchanger conversion step, the ratio of the conductivity of the carbon dioxide-dissolved water after contact with the mixed bed ion exchanger (MB1) to the conductivity of the carbon dioxide-dissolved water before contact with the mixed bed ion exchanger (MB1) ((conductivity after contact / conductivity before contact) x 100) is 90% or more.

4. The method for preparing a mixed-bed ion exchanger for hydrogen peroxide purification according to any one of claims 1 to 3, wherein the H-type cation exchanger (C1) is a strongly acidic cation exchange resin having a gel-type matrix.

5. The method for preparing a mixed-bed ion exchanger for hydrogen peroxide purification according to any one of claims 1 to 4, wherein the H-type cation exchanger (C1) is a strongly acidic cation exchange resin having an exchange capacity of 1.6 eq / L-R or more.

6. The method for preparing a mixed bed ion exchanger for hydrogen peroxide purification according to any one of claims 1 to 5, wherein the H-type cation exchanger (C1) is a cation exchange resin having an average particle diameter (harmonic mean diameter) of 0.1 mm or more and 0.4 mm or less.

7. A method for purifying hydrogen peroxide solution, comprising a step of contacting hydrogen peroxide solution with an ion exchanger, wherein the ion exchanger is a mixed bed ion exchanger (MB2) for hydrogen peroxide solution purification prepared by the method according to any one of claims 1 to 6.

8. 8. The method for purifying aqueous hydrogen peroxide according to claim 7, wherein the aqueous hydrogen peroxide after being subjected to a purification treatment using a combination of two or more selected from the group consisting of an adsorbent, an ion exchange resin, and a particulate removal filter is further purified using the mixed bed ion exchanger (MB2) for purifying aqueous hydrogen peroxide.

9. A method for purifying an ammonium bicarbonate solution, comprising a step of contacting the ammonium bicarbonate solution with an ion exchanger, characterized in that the ion exchanger is a mixed bed ion exchanger (MB2) prepared by the method described in any one of claims 1 to 6.

10. A method for purifying an ammonium bicarbonate solution as described in Claim 9, wherein the ammonium bicarbonate solution is a solution used for preparing a carbonate ion type or bicarbonate ion type anion exchange resin.

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