JPH05192592A - Treatment of strongly basic anion exchange resin - Google Patents

Abstract

PURPOSE:To obtain a hydroxide-type resin wherein no side reaction occurs and the amt. of nonionic chlorine-substd. group is made small by a method wherein a strong base anion exchange resin having quat. ammonium group is converted to an org. carboxylate type, a carbonate type or a bicarbonate type and it is heated in water. CONSTITUTION:A regeneration type strong base anion exchange resin wherein the amt. of nonionic chlorine substd. group is extremely decreased and weak basic group are hardly mixed, is obtd. by exchanging a strong base anion exchange resin having quat. ammonium group into an org. carboxylate type, a carboxylate type or a bicarbonate type, performing heat-treatment thereof in water and performing regeneration treatment. A side reaction wherein the quat. ammonium group is decomposed and is converted to a weak base group hardly occurs and anion exchange resin being suitable for treatment for water with high purity can be provided.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to an improved method for reducing nonionic chlorine substituents contained in strongly basic anion exchange resins.

[0002]

2. Description of the Related Art Strongly basic anion exchange resins are used in large amounts for deionization treatment of boiler water, process water and the like in a wide range of industrial fields in combination with strongly acidic cation exchange resins. High-temperature and high-pressure boilers used in power plants and the like require particularly high water quality. When treating high-purity water, if chloride-type exchange groups remain in the strong basic anion exchange resin, chlorine ions will be eluted from the ion exchange resin, and the chloride ion concentration in the treated water It is common to use resins with a very low content of highly regenerated chloride form in order to increase the

However, a small amount of nonionic chlorine substituents (eg, chloromethyl group, etc.) are added to ordinary strong basic resins.
It is included. If this resin is left in the hydroxide form for a long period of time, the nonionic chlorine substituent is decomposed and converted into chlorine ions, so that the amount of chloride-containing exchange groups is reduced. There is a problem. Furthermore, in U.S. Pat. No. 4,025,467 and Japanese Patent Publication No. 42542/1990, in order to reduce the amount of nonionic chlorine substituents, a chloride-type resin is used as a basic aqueous solution of at least pH 7. The resin is exposed to a high temperature to perform solvolytic substitution, and then treated with an aqueous solution of carbonate, nitric acid or sulfuric acid to give an intermediate ionic form, and then to contain chloride impurities beforehand. There is described a method of performing a two-stage conversion in which the hydroxide form is converted with sodium hydroxide treated so as not to exist. Here, the solvolytic substitution is specifically carried out by digesting the resin in a caustic solution such as sodium hydroxide at 95 ° C. for 2 hours. However, when the strongly basic anion exchange resin is heat-treated in an alkaline aqueous solution, a part of the quaternary ammonium group (strongly basic group), which is an exchange group, is removed, as described in JP-B-63-59743. Decomposes into a tertiary amino group (weakly basic group). Such decomposition of the exchange group not only reduces the exchange capacity, but also causes the following problems.

That is, in the case of a method for producing high-purity water,
Usually, the ion exchange treatment uses a column (mixed bed) packed with a mixture of a strongly basic anion exchange resin and a strongly acidic cation exchange resin. If this is used for a certain period of time and the ion exchange treatment capacity deteriorates, it becomes necessary to regenerate the ion exchange resin. Therefore, by flowing water upward from the bottom of the mixing bed, the anion exchange resin and the cation exchange resin are separated by utilizing the difference in specific gravity of each resin. Each separated resin is regenerated using a drug. Regeneration is carried out by passing sodium hydroxide or the like in the case of an anion exchange resin and by passing hydrochloric acid or the like in the case of a cation exchange resin. At the time of this separation operation, both resins are usually mixed in a small amount in the vicinity of the interface between both resins, and it is difficult to completely separate them. Therefore, when the next regeneration operation is performed in such a mixed state of both resins, there occurs a problem called reverse regeneration. That is, when regenerating the cation exchange resin, for example, when hydrochloric acid is used as a regenerant, the anion exchange resin mixed therein is converted into the chloride form. If a weakly basic group is present in the anion exchange resin, there arises a problem that washing with water after regeneration does not end easily. This occurs because the chlorine ion adsorbed on the weakly basic group is hydrolyzed and leaks out when washed with water. That is, if a weakly basic group is present in the exchange group of the strongly basic anion exchange resin, the amount of washing is significantly increased in the water washing operation after regeneration as compared with the strongly basic anion exchange resin having no weakly basic group. There is a problem.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a strongly basic anion capable of obtaining a hydroxide type resin having a reduced amount of nonionic chlorine substituents without causing a side reaction as in the prior art. The present invention relates to a method for treating an ion exchange resin.

[0006]

Means for Solving the Problems That is, the gist of the present invention is to replace a strongly basic anion exchange resin having a quaternary ammonium group with an organic carboxylate, carbonate or bicarbonate form, and The present invention relates to a method for treating a strongly basic resin that is heated by. Hereinafter, the present invention will be described in detail. The strongly basic anion exchange resin which is the subject of the present invention may be any one having a quaternary ammonium group as an exchange group. Usually, at least one kind of monovinyl aromatic compound such as styrene, vinyltoluene and ethylstyrene and at least one kind of polyvinyl aromatic compound such as divinylbenzene, trivinylbenzene, divinyltoluene and divinylxylene.
The base is a cross-linked copolymer with a seed. When producing this crosslinked copolymer, an aliphatic vinyl compound may be used in combination with the above aromatic compound. Preferred are cross-linked copolymers using styrene and ethylstyrene as the monovinyl aromatic compound and divinylbenzene as the polyvinyl aromatic compound. Here, the case where the industrial divinylbenzene contains 40% or more of ethylstyrene is also included.

Then, a chloroalkyl group such as a chloromethyl group is introduced into such a crosslinked copolymer by using a suitable haloalkylating agent and a catalyst, and then a tertiary amine such as dimethylethanolamine, trimethylamine and triethylamine is reacted. , A quaternary ammonium group, and the like. The polyvinyl aromatic compound is used in the range of 1 to 25% by weight with respect to the total amount of the aromatic compound.
The production of a copolymer from a monovinyl aromatic compound and a polyvinyl aromatic compound is generally carried out by suspension polymerization,
In an aqueous dispersion medium containing a medium that is a solvent in an aqueous medium or for these aromatic compounds, but is a non-solvent for the cross-linked copolymer to be produced, in the presence of a polymerization initiator,
Polymerize under heating

The medium used for the polymerization is toluene,
Examples thereof include xylene and isooctane. As the polymerization initiator, benzoyl peroxide, lauroyl peroxide, azobisisobutyronitrile, tertiary butyl peroxide, etc. are used. Although the temperature of the polymerization reaction depends on the type of catalyst, it is usually in the range of 50 to 100 ° C.

Examples of the haloalkylating agent used for haloalkylation include chloromethyl methyl ether, chloroethyl methyl ether, chloromethyl ethyl ether, bromomethyl methyl ether, bromoethyl methyl ether and bromomethyl ethyl ether. Examples of the haloalkylation catalyst include zinc chloride, anhydrous aluminum chloride, tin chloride, iron chloride and the like. The catalyst is used in a proportion of 1 to 100% by weight based on the copolymer. Alternatively, the haloalkylation can be carried out using, for example, a mixture of formaldehyde and hydrochloric acid. These reactions are usually carried out in an organic solvent such as ethylene dichloride, propylene dichloride or chlorobenzene at a temperature of 40 to 60 ° C. for several hours to about one day.

Next, NR ¹ R ² R ³ (R ¹ , R ² was added to the thus-produced crosslinked copolymer having a haloalkyl group.
² and R ³ each represent an alkyl group such as a methyl group or an ethyl group, a hydroxyalkyl group such as a (β-) hydroxyethyl group, a benzyl group or a phenyl group) 3
React with a primary amine. Specific examples of the tertiary amine include
Examples include trimethylamine, triethylamine, tripropylamine, dimethylethylamine, dimethylbenzylamine, dimethylethanolamine, dimethylaniline, tributylamine, diphenylethylamine and benzylphenylmethylamine. The reaction with the amine is carried out at room temperature or at an elevated temperature.

The resin produced as described above is generally commercially available, and DIAION (registered trademark) SA is used.
10A, SA12A, SAN1, SA20A, PA31
2, PA418 (trade name, manufactured by Mitsubishi Kasei Co., Ltd.), Amberlite (registered trademark) IRA400, IRA41
0, IRA900, IRA910 (above trade name, US R
ohm & Haas or Tokyo Organic Co., Ltd., Dowex (registered trademark) SAR, SAR-P, SBR (the above trade names, manufactured by Dow Chemical in the United States) and the like.

In the method for treating a strongly basic anion exchange resin of the present invention, such a generally commercially available resin is treated by a simple method so that a weakly basic group is not generated and a large amount is obtained at the time of use. It is characterized in that it can reduce the problematic nonionic chlorine to such an extent that it can hardly be measured. In addition to the above-mentioned production method, these resins are produced by producing a cross-linked copolymer of vinylbenzyl chloride and divinylbenzene, which are monomers into which halogen atoms have been introduced in advance, and tertiary amines such as trimethylamine, triethylamine and dimethylethanolamine are produced. It is also manufactured by reacting with.

In the present invention, in order to make the quaternary ammonium group of the strongly basic anion exchange resin into an organic carboxylic acid salt type, a polycarboxylic acid such as acetic acid, propionic acid, lactic acid or the like, malic acid, citric acid or the like is used. An organic acid such as a carboxylic acid or an organic acid salt such as an alkali metal salt or an ammonium salt of these organic acids is used. Further, for the carbonate type or bicarbonate type, those acids or salts of these acids such as alkali metal salts or ammonium salts are used. Among the above-mentioned agents, acetic acid, sodium carbonate, sodium bicarbonate and sodium acetate are particularly preferably used. These organic carboxylic acids or carbonates or bicarbonates are passed through a resin column in the form of an aqueous solution of 0.1 to 30%, preferably 5 to 15% or a water-containing methanol or ethanol solution to form an organic carboxylate salt. Alternatively, it is converted into a carbonate form or a bicarbonate form (hereinafter collectively referred to as “carboxylate form etc.”). The conversion to the carboxylate salt form and the like can also be carried out in a batch system. Amount of carboxylic acid used, amount of carboxylic acid salt,
The amount of carbonate and the amount of bicarbonate are preferably equivalent to or more than the exchange capacity of the resin, but more preferably 1.2 to 3 times the exchange capacity of the resin. The higher the exchange rate to the carboxylate salt form, the more preferable, and usually 90% or more, particularly 95
% Or more is preferable. Usually, the heating temperature in water of the ion exchange resin in the form of carboxylate is 75 ° C or higher, preferably 95-120 ° C. Time required for heat treatment is 1-20
Hours, preferably 6-12 hours. After heat treatment, washing with water and regenerating according to the usual method, the nonionic chlorine substituents are extremely reduced, and a regenerating strong basic anion exchange resin with almost no weak basic groups is provided. To be done.

The ion exchange resin of the present invention thus produced is treated in a regenerated form according to a known method,
used. As a reproducing method, for example, US Pat.
As described in Japanese Patent Publication No. 025467, a two-stage regeneration method is used in which after converting to an intermediate ionic form with sodium bicarbonate or sodium carbonate, etc., it is converted into a hydroxide form with sodium hydroxide or the like. Is preferred.

[0015]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. (Example 1) 200 ml of a chloride type commercially available porous strongly basic anion exchange resin Diaion (registered trademark) PA312 (manufactured by Mitsubishi Kasei Co., Ltd.) was packed in a glass column, and 8% by weight of sodium hydroxide was added. 4000 ml of an aqueous solution was passed for 2 hours and then washed with 1000 ml of demineralized water to obtain a hydroxide form. 12% by weight acetic acid aqueous solution 2000 to this resin
After passing ml for 1 hour to convert to acetate form, demineralized water 10
It was washed with 00 ml. The resin thus converted into the acetate salt form was added to 3 times the amount of demineralized water, and heat-treated at 100 ° C. for 8 hours with stirring in a round flask. The pH of the liquid during the heat treatment gradually changed from 4.4 immediately after the start of heating to 4.7 after 8 hours, but it was always kept on the acidic side.

Each of the resin samples before and after the heat treatment was packed in a column, and a 15% aqueous nitric acid solution was passed in an amount of 20 times to remove all ionic chlorine and thoroughly wash with demineralized water.
This resin sample is included in these samples by known activation analysis (see “New Experimental Chemistry Course 11” edited by Chemical Society of Japan, p89-p103 and “Instrument Analysis” published by Shokabo, 12th edition, p316-p329, etc.). The amount of nonionic chlorine substituent was measured. In addition, the weakly basic group content was determined by measuring the difference between the hydrochloric acid adsorption capacity and the salt decomposition capacity of the heat-treated sample. Further, as Comparative Example 1, the same commercially available resin as in Example 1 was used, and the performance of the resin heat-treated at 100 ° C. for 2 hours in a 4% by weight aqueous sodium hydroxide solution having a volume twice that of the resin was similarly measured. ..

The results are shown below.

[Table 1] Nonionic chlorine substituent content Weakly basic group content Before heat treatment 780ppm 0.00meg / ml-resin After heat treatment 70ppm 0.00meg / ml-resin Comparative example 1 140ppm 0.05meg / ml-resin

Example 2 A commercially available gel type strongly basic anion exchange resin, Diaion (registered trademark) SA10A (manufactured by Mitsubishi Kasei Co., Ltd.) was used, except that acetic acid was changed to propionic acid in Example 1. By the same treatment, conversion to a propionic acid form and heat treatment were performed. Further, as Comparative Example 2, the same commercially available resin as that used in Example 2 was heated at 100 ° C. for 4 hours in a 6 wt% aqueous sodium hydroxide solution having twice the volume of the resin.
The performance of each of the obtained resins was measured in the same manner as in Example 1 and is shown below.

[0019]

[Table 2] Nonionic chlorine substituent content Weakly basic group content Before heat treatment 690ppm 0.00meg / ml-resin After heat treatment 84ppm 0.00meg / ml-resin Comparative example 2 160ppm 0.04meg / ml-resin

(Example 3) The strongly basic anion exchange resin DIAION (registered trademark) PA312 (chloride form)
After converting 200 ml to the hydroxide form by the same treatment as in Example 1 and washing with water, 2000 ml of an 8 wt% sodium carbonate aqueous solution was passed for 1 hour to convert to the carbonate form, and then 100 ml of demineralized water was added.
Wash with 0 ml. The resin converted to the carbonate form was heat-treated in the same manner as in Example 1. The performance of the obtained resin is measured in the same manner as in Example 1 and shown below.

[0021]

Table 3 Nonionic chlorine substituent content Weakly basic group content Before heat treatment 780 ppm 0.00meg / ml-resin After heat treatment 90ppm 0.00meg / ml-resin Comparative example 1 140ppm 0.05meg / ml-resin

Example 4 The gel type strongly basic anion exchange resin DIAION (registered trademark) SA10A was converted into a bicarbonate form by the same treatment as in Example 3 except that sodium carbonate was used instead of sodium bicarbonate. After that, heat treatment was performed. The performance of the obtained resin was measured in the same manner as in Example 1, and the results are shown below.

[0023]

Table 4 Nonionic chlorine substituent content Weakly basic group content Before heat treatment 690ppm 0.00meg / ml-resin After heat treatment 95ppm 0.00meg / ml-resin Comparative example 2 160ppm 0.04meg / ml-resin ( Reference example) Water washability evaluation of anion exchange resin

A strongly basic anion exchange resin (Sample-1) having a weakly basic group content of 0.00 meq./ml-Resin prepared in Example 1 above and a method according to Comparative Example 1 The content of weakly basic groups produced in
Strongly basic anion-exchange resin of 0.04 meq./ml-Resin (referred to as sample-2 and -3 in this order) was completely converted into chloride form using the above-mentioned 2N hydrochloric acid aqueous solution, and then washed thoroughly with water. And weigh exactly 10 ml. The small column made of glass is filled with the resin, demineralized water is caused to flow at a flow rate of 10 l / hr, and the specific resistance value of water at the column outlet is measured. A small specific resistance value means that chlorine ions are present in water. The result is shown in FIG. From FIG. 1, it can be seen that the presence of weakly basic groups significantly deteriorates the water washability.

[0025]

INDUSTRIAL APPLICABILITY According to the method of the present invention, it is possible to provide an ion exchange resin having a reduced amount of nonionic chlorine substituents, which is suitable for high-purity water treatment. Therefore, the present invention is very useful industrially. is there. Further, compared with the conventional hydrolysis treatment in the presence of alkali, there is almost no side reaction that the quaternary ammonium group is decomposed and converted into a weakly basic group, which is advantageous.

[Brief description of drawings]

FIG. 1 is a comparison result of water washability of a resin with and without a weakly basic group in the strongly basic anion exchange resin shown in (Reference Example).

Claims (1)

[Claims] 1. A strong base characterized in that a strongly basic anion exchange resin having a quaternary ammonium group is converted into an organic carboxylate salt form, a carbonate salt form or a bicarbonate salt form, and then heated in water. Method of reactive resin