JPH06254550A - Removing method of silica - Google Patents

Abstract

PURPOSE:To improve the efficiency of removing silica when water containing silica is brought into contact with an anion exchange resin to adsorb and remove ions, by using a crosslinked copolymer expressed by specified formula as the anion exchange resin. CONSTITUTION:A dry resin consisting of a crosslinked copolymer described bellow having 1.5-8.5 milliequiv./g neutral salt decomposition capacity is used as the anion exchange resin to adsorb and remove ions. The crosslinked copolymer consists of 30-99.5mol% unit having anion exchange groups selected from groups of repeating units expressed by general formulae 1, 2, 0.1-40mol% repeating unit expressed by general formula 3, and 0-44mol% repeating unit derived from other monomers having double bonds which are copolymerizable with monomers of general formulae 1-3. In formulae, R<1>-R<3> are methyl groups or ethyl groups, R<4>, R<5> are hydrogen atoms, methyl groups or ethyl groups, and R<6>, R<7> are hydrogen atoms or alkyl groups of 1-3 carbon number.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for removing silica. Furthermore, the present invention relates to a novel method for removing silica, in which a silicic acid compound or colloidal silica present in an aqueous solution is brought into contact with a crosslinked copolymer having a polyvinylamine structure and adsorbed or separated. The method of the present invention can be used not only for general water treatment but also for pure water production such as semiconductor production water, nuclear power water, thermal power generation water, and pharmaceutical / cosmetics production water.

[0002]

2. Description of the Related Art So far, many proposals have been made for removing silica using ion exchange resins. For example, as described in JP-A-4-244207, JP-A-3-80989, JP-A-2-135147, JP-A-1-284386 and the like, currently used silica-removing resins are , A strongly basic styrene anion exchange resin. A trimethylamino group, a hydroxyethyldimethylamino group, and a hydroxypropyldimethylamino group are used as the ion-exchange group of the strongly basic group.
For example, Diaion (registered trademark) SA10A, SA1
2A (all manufactured by Mitsubishi Kasei) and Amberlite (registered trademark) IRA-400 (manufactured by Rohm & Haas).
However, the styrene-based anion exchange resin has the following problems.

Benzyl group in composition (-C ₆ H ₄ CH ₂
-) Does not participate in the ion exchange capacity at all, and thus has a low ion exchange capacity per unit weight. For example, a styrene-based polymer (quaternary ammonium methylstyrene type) in which the content of a cross-linking agent component to which an ion exchange group is difficult to bond is 0%.
Assuming that, the ion exchange capacity calculated assuming that one ion exchange group is bonded per benzene ring is assumed to be close to the maximum, but the ion exchange capacity of this resin is quaternary ammonium group ( OH) type is 5.2 meq / g and the polyvinylamine resin calculated in the same manner is 9.5.
Meq / g, but small.

The styrene-based anion exchange resin has a problem that it tends to nonspecifically adsorb organic substances because of its strong hydrophobicity. It is considered that this is because the benzyl group portion is hydrophobic. The market demands an anion exchange resin that absorbs a large amount of silica and does not easily adsorb organic substances. In the case of a styrene-based anion exchange resin, most of the ion exchange groups in the total exchange capacity are strong electrolytes, and in the case of a strongly basic resin, there is a problem that the regeneration efficiency is low even when regenerated with an aqueous sodium hydroxide solution. Since the exchange of the chloromethyl group for the amino group does not proceed completely in the middle of the reaction step, a part of the chloromethyl group remains after the amination. As a result, when the exchange resin is used in the OH form, the organic chlorine compound derived from the chloromethyl group leaks due to hydrolysis. In some cases, this also causes the problem of container corrosion.

On the other hand, (meth) acrylic acid ester type and (meth) acrylamide type anion exchange resins have been proposed. However, the biggest problem with these anion exchange resins is that the ester or amide groups are susceptible to hydrolysis by acidic or basic solutions. That is, since the anion exchange resin is exposed to a basic solution such as an aqueous solution of sodium hydroxide during regeneration, chemical stability such as acid resistance or anion resistance of the ion exchange resin matrix is an important factor. Therefore, the usable range of the (meth) acrylic acid-based ion exchange resin and the (meth) acrylamide-based ion exchange resin is limited.

In order to avoid the above-mentioned problems of the styrene type, (meth) acrylic acid type and (meth) acrylamide type anion exchange resins, linear polyvinylamines and polyamines capable of reacting with amino groups of the linear polyvinylamines are used. A method has been proposed in which a gel-type crosslinked spherical resin is obtained by reacting with a functional crosslinking agent (see JP-A-61-51006). However, in this production method, water is used as a solvent to dissolve the linear polyvinylamine, and as a result,
Since water serves as a diluting solvent, the degree of swelling of the resulting cross-linked copolymer is high, and the ion exchange capacity per volume remains low.

On the other hand, a crosslinkable monomer such as polyethylene vinyl aromatic monomer such as divinylbenzene and abbreviated as DVB hereinafter, poly (meth) acrylate or poly (meth) acrylamide type monomer and N-vinylformamide (hereinafter , Abbreviated as NVF) and hydrolyzing the formamide group of the resulting crosslinked polymer to obtain a polyvinylamine crosslinked product having a primary amine (for example, JP-A-61-151007). (See the official gazette). However, when a polyethylene aromatic monomer is used as the crosslinkable monomer, only a gel-shaped amorphous product can be obtained because solution polymerization is used. Further, when a (meth) acrylate or (meth) acrylamide monomer such as ethylene glycol dimethacrylate (hereinafter abbreviated as EGDM) or methylenebisacrylamide is used as the crosslinkable monomer, an ester bond, an amide Since the bond is easily hydrolyzed in an acidic or basic solution, the range of use was limited.

H. Tbal et al. Reported a polyvinylamine polymer, a method for producing the same, and properties as a chelate resin (Eur. Polym, J, .25, 4, 3).
31-340 1989, Reactive Poly
mers, 17.207-217, (1992), J. Am.
M. S. Pure and chem A29 (8) 6
99 (1992) etc.). In this proposal, a polyvinylamine copolymer having a high specific surface area is obtained by hydrolyzing N-vinyl- ^t- butyl carbamate and DVB, EGDM or the like in the presence of heptane or the like to obtain a porous polymer by suspension polymerization. Is getting However, the anion exchange capacity of the resulting polymer is only 4.3 meq / g-dry resin. Further, according to these documents, this cross-linked polymer is only a primary amine resin, and there is no report on a method for producing a quaternary ammonium group used for water treatment or adsorption / removal of silica.

[0009]

DISCLOSURE OF THE INVENTION The present invention provides a method for efficiently removing silica in water by using an anion exchange resin having a large ion exchange capacity per unit weight and non-specific adsorption of organic substances. It is intended to be provided.

[0010]

The summary of the present invention is as follows.
In the method of adsorbing silica to the ion-exchange resin to remove the silica by bringing water containing silica into contact with the anion-exchange resin, the ion-exchange resin is represented by the general formula (I)
And an anion-exchange group selected from the group consisting of the repeating unit represented by the general formula (II) and the general formula (III
0.1 mol% to 40 mol% of the repeating unit represented by the formula (1), and a double bond copolymerizable with the monomer giving the general formula (I), the general formula (II) and the general formula (III). Repeating units derived from other monomers 0 mol% to 4
An anion exchange resin comprising 0 mol% of a cross-linked copolymer having a neutral salt decomposing capacity of 1.5 to 8.5 meq / g-dry resin. And the method of removing silica.

[0011]

[Chemical 4]

[0012]

[Chemical 5]

[0013]

[Chemical 6]

The present invention will be described in detail below. The method for producing the anion exchange resin, which is a feature of the present invention, is not particularly limited, but as a raw material monomer giving the general formula (I) or (II), the raw material is inexpensive, easy to hydrolyze, etc. It is particularly preferable to use NVF, which has characteristics such as good copolymerizability with the monomer component (1). N
The content of VF is 30 mol% to 99.5 mol%, particularly preferably 40 mol% to 95 mol% with respect to the total amount of monomers because an ion exchange group is introduced from NVF. Is.

As the monomer giving the unit of the general formula (III), a polyethylene monomer such as DVB, divinyltoluene or divinylxylene is a monomer having two or more ethylenically unsaturated double bonds. It is a body compound and is called a crosslinking agent. In order to make the resulting resin water-insoluble, these crosslinking agents are essential constituent components, but they must be added to the extent that the significance of imparting a high ion exchange capacity is not lost. Therefore, the content of the cross-linking agent is 0.1 mol% to 40 mol%, more preferably 0.5 mol% to 30 mol%.

For the purpose of imparting various properties to the resin of the present invention, in addition to the above NVF and polyethylene monomers, monomers copolymerizable therewith, such as styrene derivatives, (meth), It is also possible to intentionally add acrylic acid ester, (meth) acrylamide, (meth) acrylonitrile and the like. The content of units derived from the copolymerizable monomer is preferably 0 to 40 mol% based on the copolymer. The content of each of these monomers corresponds to the content of the repeating unit in the copolymer, and since these amounts are difficult to measure as a component of the copolymer, the reaction among the charged monomers is Express it instead of the amount you have done.

The ion exchange resin used in the present invention is preferably spherical. The spherical resin can be obtained by various suspension polymerization methods. An organic solvent that is incompatible with NVF is used as the solvent that forms the bath in the suspension polymerization system. For example, aliphatic or aromatic hydrocarbons such as toluene, petroleum ether and cyclohexane, and halogeno compounds such as polychloroalkane and chlorobenzene can be used. The ratio of the polymerization bath in suspension polymerization is generally N
The polymerization bath phase is in a range of 1 to 5 volumes with respect to 1 volume of a monomer phase containing VF and a crosslinking agent (NVF phase). The NVF phase is dispersed in the polymerization bath by a continuous dropping method in which the NVF phase solution is supplied while stirring the bath to form droplets, a batch dropping method in which the NVF phase solution is collectively charged in the bath, and a nozzle. Therefore, an introduction method such as dropping or jetting a droplet into the solution can be used.

N is added to the polymerization system of the present invention as a porosifying agent.
By adding a solvent which is a solvent of VF and miscible with water, for example, a single solvent such as acetone, 1-propanol, 2-propanol, and ethanol, a mixed solvent of methanol and 1,4-dioxane, methanol and tetrahydrofuran, and the like, It is possible to obtain a porous structure. The physical properties of pores differ depending on the content thereof, and are preferably 0.1 to 200% by weight with respect to the polymerizable monomer. In addition to the above solvent that functions as a porosifying agent, examples of linear polymers that can be a porosifying agent include polyvinylpyrrolidone, polyethylene glycol, and ethyl cellulose. In the case of a resin having a porous structure, its preferred physical properties are a specific surface area of 1 to 500 m ² / g-dry resin and a pore diameter of 0.5 to 500 nm. The specific surface area and the physical properties of pores in the present invention are measured by a nitrogen adsorption method, a mercury intrusion method or the like.

The polymerization initiator used for the polymerization is selected from various polymerization initiators, for example, 2,2-azobis-2-amidinopropane hydrochloride and 4,4-azobis-4.
-An azo polymerization initiator such as cyanovaleric acid is used,
The amount used is generally in the range of 0.02% by weight to 5.0% by weight based on the total amount of the monomers. The polymerization conditions in the present invention vary depending on the monomer components, but the polymerization temperature is usually 30
~ 120 ° C, and the polymerization time is usually in the range of 1 hour to 15 hours.

In the present invention, the average particle size of the resin is 1 μm.
It is preferably m to 2 mm. More preferably 30
It is 0 to 1000 μm. The copolymer of the obtained NVF cross-linked polymer is hydrolyzed with, for example, an aqueous solution of hydrochloric acid, sulfuric acid, sodium hydroxide, potassium hydroxide or the like. The reaction temperature of the hydrolysis is 50 to 120 ° C, and the reaction time is usually 1 to
It is preferably performed for 10 hours. Under these reaction conditions, the formamide group can be almost completely hydrolyzed, and a primary amine type resin can be obtained.

The alkylation of this primary amine type resin may be carried out by a known method. For example, dimethyl sulfate,
A strong basic resin of polyvinylamine resin can be synthesized by acting a reagent such as diethylsulfate, methyl halide or ethyl halide on the primary amine type resin and thoroughly alkylating it. Alternatively, a strong basic anion exchange resin can be produced by a reaction using a formic acid-formalin system, via a tertiary amine resin, and alkylation by the above method.

The maximum ion exchange capacity (theoretical amount) of the polyvinylamine-based resin is such that when the substituent is a trimethylamino group, assuming that the ion exchange group does not bind to the resin and the cross-linking agent content is 0%, ammonium (OH) In the case of the shape resin, it is 9.5 meq / g-dry resin. While the value similarly obtained with the existing styrene resin is 5.2 meq / g-dry resin, the exchange capacity per unit weight is about 1.8 times in the case of trimethylammonium (OH type). As described above, the polyvinylamine-based resin has a larger ion exchange capacity than the styrene-based resin because of its structure. Therefore, it is particularly suitable for water treatment that requires a large amount of treatment in a short time. It is possible.

Generally, what is called silica is insoluble or soluble, the former is a suspending solid or colloidal one, and the latter is usually Si (OH) _{3 in} natural water. ^- exists as, in the low density-neutral region exists at SiO ₆ (OH) ₆ ^2- forms. The strong basic ion exchange resin of the present invention is capable of capturing and adsorbing not only soluble silica but also suspended particulate insoluble silica.

In the present invention, the quaternary ammonium group content is preferably 30 mol% or more. Of course,
It may be an anion exchange resin in which a weakly basic group and a strongly basic group are mixed, and is a mixture of an anion exchange resin having only a weakly basic group and an anion exchange resin having only a strongly basic group. It may be.

It is known that the strongly basic component is an essential ion exchange group for the anion exchange resin to adsorb silica. On the other hand, weakly basic resins (primary amine, secondary amine or tertiary amine) hardly adsorb silica. However, the neutral salt decomposition capacity is about 1.3 me.
Polyvinylamine cross-linked strong base anion exchange resin having a neutral salt decomposing capacity smaller than that of a styrene-based strong base anion exchange resin having q / ml (for example, Diaion SA10, SA20, etc.). Was found to have a higher silica adsorption capacity. It is considered that this is because the weakly basic component also adsorbed silica due to the difference in the basic structure of the polyvinylamine-based matrix and the basicity of the amine. That is, polyvinylamine copolymer, a benzyl group - containing no _{(-C 6 H 5 -CH 2)} . Since the polyethylene chain is covered with hydrophilic amine,
It is very hydrophilic. Therefore, when the polyvinylamine polymer is used as an anion exchange resin for removing silica, it has a characteristic that it is difficult to adsorb organic substances. The method for removing silica of the present invention is not particularly limited. Examples of its usage include various usage methods such as a method of incorporating an ion exchange resin in a part of a multi-tower apparatus (single bed / single tower method) or a mixed bed, or a batch method.

NaOH as well as ordinary anion exchange resins
It can be regenerated with a basic aqueous solution such as. The resin used in the present invention has higher regeneration efficiency than conventional styrene-based anion exchange resins and is suitable for a general field of water treatment. That is, in the present invention, the ion exchange resin is not necessarily 4
The content of the quaternary ammonium group need not be 100%. As the content of the weak base increases, the regeneration efficiency increases and the amount of the regenerant decreases.

[0027]

The present invention has a large adsorption capacity for silica,
The present invention proposes a method for removing silica using a polyvinylamine cross-linked copolymer having high regeneration efficiency and excellent chemical stability. The field of application of the present invention is the same field of application as the ion exchange resins currently used. For example, for softening normal boiler feed water, for producing pure water for semiconductor production,
It can be used in a wide range of water treatment fields such as the production of pure water for (nuclear) power plants.

[0028]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the following examples, meq / g represents milliequivalent per dry resin weight.

<Method for measuring ion exchange capacity> About 15 ml of the crosslinked polymer obtained in the Production Example was packed in a column,
Space velocity (SV) 7 with 500 ml of 2N-NaOH aqueous solution
Flush with 0, then wash 1 liter of demineralized water with SV20,
The counterion was OH type. Exactly 10.0 ml of this resin was sampled with a graduated cylinder and packed in a column. Into this, 250 ml of 5% NaCl aqueous solution was poured by SV20,
Received in a volumetric flask. This solution was titrated with acid and base to measure the strong base exchange capacity. 0.1N-HC in this column
l 100 ml of an aqueous solution was flown with SV10, the effluent was received in a measuring flask, and 50 ml of methanol was further flowed to wash the resin layer. Further, the liquid remaining in the resin layer was extruded by compressed air to collect these solutions. The solution was acid-base titrated. This measured the weak base exchange capacity. Separately, OH
10.0 ml of the mold resin was drained with a centrifuge to remove the attached water. The resin was dried at 60 ° C. for 5 hours. The weight of the dry resin was measured and converted into an ion exchange capacity per weight.

<Analysis method of cross-linked polymer> The composition of the polymer was analyzed by ¹³ C-NMR (CP-MAS method, comparison of CHO group (163 ppm) and sum of area ratios of benzene ring ipso position and ortho position. )) And elemental analysis.

[Production Example-1] <Polymerization reaction> A 1000 ml 4-neck flask was charged with 400 ml of cyclohexane and 800 mg of ethyl cellulose to prepare a polymerization bath solution. On the other hand, NVF (purity 94%,
Impurities mainly contain formic acid) 180g, divinylbenzene (purity> 80%) 20.0g, demineralized water 4.5g, V-5
0 (azo polymerization initiator, trade name, manufactured by Wako Pure Chemical Industries, Ltd.) 4
A 00 mg solution was prepared. Both solutions were previously bubbled with nitrogen, and the following polymerization reaction was performed in a nitrogen atmosphere.
The NVF phase solution prepared above was gradually added dropwise while stirring the cyclohexane solution at 100 rpm. After stirring for 30 minutes, the temperature was raised and polymerization was carried out at 65 ° C. for 8 hours. After the temperature was raised, the NVF phase gelled in about 15 minutes. After completion of the polymerization, the cross-linked copolymer was placed in a Buchner funnel, washed with methanol, and then washed with water. The polymerization yield was 81% based on the raw material monomers. The resulting crosslinked copolymer was white in appearance, but was slightly opaque when observed under a microscope. The degree of swelling of the obtained polymer in demineralized water was 4.63 ml /
The water content was 68.9%. This polymer was a gel-type cross-linked copolymer and had a specific surface area of 0 m ² / g.

<Hydrolysis reaction> The above drained crosslinked polymer was placed in a 1 liter flask and 2N-NaOH was added.
700 ml of an aqueous solution was added. Warm the solution to 4 ° C at 85 ° C.
Hydrolyzed for hours. After the reaction was completed, the polymer was washed with water to give a regenerated form. The obtained crosslinked copolymer was a primary amine type, and had a swelling degree of 7.33 ml / g and a water content of 7
It was 8.9%. Weak base exchange capacity is 18.0 meq /
It was g (2.46 meq / ml). This crosslinked copolymer was designated as Comparative Example-1.

<Alkylation Reaction> The crosslinked polymer (regenerated form) obtained by the hydrolysis reaction was used to methylate the amine. To a 500 ml four-necked flask, 150 ml of the drained polymer and 50% methanol aqueous solution were added.
ml was added. To this, 50 ml of a methanol solution of 30 ml of methyl iodide and an aqueous solution containing 28 g of sodium carbonate were slowly added dropwise. The polymer became heavier and precipitated as the reaction proceeded. After completion of the reaction, the polymer was placed in a Buchner funnel and washed with methanol and demineralized water. The neutral salt decomposition capacity of the obtained anion exchange resin was 3.50 meq / g (0.66 meq / ml), and the weak base exchange capacity was 2.54 meq / g (0.48 meq / m).
l).

Production Method Using the regenerated cross-linked polymer (Comparative Example-1) obtained by the hydrolysis reaction in Production Example-1, a tertiary amine tertiary reaction was carried out. 100 ml of cross-linked copolymer, 100 ml of demineralized water
In a 500 ml flask, formic acid 38 g, 37%
87 g of aqueous formaldehyde solution was added. Further, an aqueous sodium hydroxide solution was added to adjust the pH to 5. The temperature was gradually raised and the reaction was carried out at 90 ° C. for 5 hours. CO ₂ was generated violently in the initial stage, but at the end of the reaction, it hardly generated. After the reaction was completed, the crosslinked copolymer was washed with water. The weak base exchange capacity of the obtained crosslinked copolymer was 9.6.
It was meq / g. The average particle size of the polymer is about 410 μm
Met. It was considered that 90% or more of the tertiary amine was contained in the anion exchange group, and the rest was a mixture of primary amine and secondary amine. Since it is a gel-type cross-linked copolymer, its specific surface area is 0
It was m ² / g. This crosslinked copolymer was designated as Comparative Example-2.

<Method for measuring silica removing ability of resin> Method for preparing raw aqueous solution In 20 liters of demineralized water, anhydrous sodium sulfate (special grade:
2.981 g, manufactured by Kishida Chemical Co., Ltd., 420 ml of 0.1N hydrochloric acid aqueous solution, sodium metasilicate nonahydrate (special grade:
(Manufactured by Kishida Chemical Co., Ltd.) was dissolved to prepare a raw aqueous solution. The composition of the raw aqueous solution is 300 ppm (calculated as CaCO ₃ , SO ₄
²⁻ / Cl ⁻ = 1.00 and the SiO ₂ abundance ratio was 30%.

Method for measuring silica concentration In 50 ml of sample solution, 1 ml of hydrochloric acid solution (1 volume of 35% hydrochloric acid + 1 volume of deionized water), ammonium molybdate.
2 ml of tetrahydrate (special grade: manufactured by Kishida Chemical Co., Ltd.) (solution of ammonium molybdate tetrahydrate 5.30 g dissolved in deionized water 50 ml) was added and left for 5 minutes. Furthermore, 20 g of oxalic acid solution (oxalic acid dihydrate (manufactured by Tokyo Kasei))
Was dissolved in demineralized water to make 200 ml) 1.50 m
1, 1-amino-2-naphthol-4-sulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) (0.500 g of 1-amino-2-naphthol-4-sulfonic acid and sodium sulfate (special grade: manufactured by Kishida Chemical Co., Ltd.) 2.00 g Is dissolved in 50 ml of demineralized water, while sodium hydrogen sulfate (special grade: manufactured by Kishida Chemical Co., Ltd.) 20
g was dissolved in 120 ml of demineralized water, both solutions were mixed, and 2.00 ml of a solution in which the total amount was 200 ml with demineralized water was added, and the mixture was left for 10 minutes. The absorbance at 815 nm of the obtained solution (U-1100 type ratio beam spectrophotometer, manufactured by Hitachi Ltd.) was measured, and the silica concentration was calculated from a calibration curve measured in advance.

Measurement of calibration curve A 1000 ppm Si standard solution for atomic absorption analysis (manufactured by Wako Pure Chemical Industries) was diluted with demineralized water to prepare a calibration curve in the range of 5 ppb to 5 ppm. The silica concentration is shown as converted to SiO ₂ .

Measurement method of column water flow test A raw water preparation solution was used as a Diaion SK1B (regenerated type) (Mitsubishi
A column (2.0 cmφ) packed with 180 ml of Kasei Co.
X about 58 cm) SV = 7.8 hr^-1Got through after passing by
The prepared solution was temporarily stored in a 1-liter Erlenmeyer flask. This
Column packed with anion exchange resin (1.36
cmφ × about 14 cm) SV = 20 hr ^-1Passed through (Yin
The ion exchange resin was regenerated with 2N-NaOH aqueous solution.
After that, wash with water and 10 times just before passing the raw water through the column.
Wash with an amount of demineralized water. Anion exchange tree like this
20.0 ml of fat was taken and packed in a column). Yin Io
The solution passed through the resin is a conductivity cell (Toa Denpa Co., Ltd.).
Manufacturing: Cell constant 0.10), and the conductivity of the eluent is constantly maintained.
It was measured. Also, sample the eluent periodically to obtain
The silica concentration of the prepared solution was measured by the method described above.

Measurement Samples The samples used in the test are Production Example-1, Comparative Example-1, Comparative Example-2, and SA10 of diaion strongly basic resin.
A, SA20A and weakly basic resin WA30 (all manufactured by Mitsubishi Kasei).

[0040]

[Table 1] * 1: Processing amount at the start of leak * 2: Processing amount when BTP is 1 ppm

[0041] Despite WA30 is a weak base resin, for adsorbing SiO ₂ is believed to contain some strong base component.

Resin Regeneration Method A large excess of 2N was added to 25 ml of anion exchange resin (OH type).
An aqueous solution of —HCl was passed through to form a complete C1 form. The resin was washed with demineralized water. An aqueous solution of NaOH equivalent to twice the total exchange capacity was passed through these resins at SV5hr ^-1 ,
The anion exchange resin was regenerated. On the other hand, the cation exchange resin SK1B used was completely regenerated with a 2N-HC1 aqueous solution. These anion exchange resin and SK1B resin were mixed bed type and packed in a column.

[0043]

[Table 2] * 1: Processing amount at the start of leak * 2: Processing amount when BTP is 1 ppm

Claims (1)

[Claims] 1. A method of adsorbing silica to the ion-exchange resin by bringing water containing silica into contact with the anion-exchange resin, in which the ion-exchange resin is represented by the general formula (I). A repeating unit represented by the general formula (II) and a unit having an anion exchange group selected from the group consisting of 30 mol% to 9
0.1 mol% to 40 mol% of the repeating unit represented by the general formula (III) having 9.5 mol% and a unit giving the general formula (I), the general formula (II) and the general formula (III). A cross-linked copolymer comprising 0 to 40 mol% of repeating units derived from another monomer having a double bond copolymerizable with a monomer, the neutral salt decomposition of the cross-linked copolymer. A method for removing silica in water, which comprises using an anion exchange resin having a capacity of 1.5 to 8.5 meq / g-dry resin. [Chemical 1] [Chemical 2] [Chemical 3]