JPH10225644A - Method for regenerating strongly basic anion-exchange resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the desorption rate of an org. matter at the time of regenerating a strongly basic anion-exchange resin having adsorbed the org. matter in desalting and having a specified structural unit by bringing an aq. sodium chloride soln. heated above a specified temp. into contact with the resin to desorb the org. matter. SOLUTION: This strongly basic anion-exchange resin is used to adsorb the impurities such as inorg. ions and org. matter contained in the raw water such as industrial water and contains a structural unit shown by the formula and having a quaternary ammonium salt group and a structural unit derived from an unsaturated hydrocarbonic group-contg. cross-linkable monomer. When the resin is regenerated, an aq. sodium chloride soln. heated to >=50 deg.C is brought into contact with the resin to desorb the org. matter. In the formula, A is 4-9C alkoxymethylene groups, etc., R<1> is 1-4C alkyls, R<2> and R<3> are 1-4C hydrocarbonic groups, and X is a counter ion coordinated to the ammonium group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for regenerating a strongly basic anion exchange resin, and more particularly, to a method for regenerating a strongly basic anion exchange resin which has been subjected to a desalting treatment to adsorb organic substances. The present invention relates to an improvement in a method for regenerating a strongly basic anion exchange resin, which enables effective regeneration at a relatively high temperature by using a basic anion exchange resin.

[0002]

2. Description of the Related Art In the production of pure water, an ion exchange method is widely used to remove impurities contained in raw water such as river water, industrial water, and tap water.

[0003] A strongly basic anion exchange resin adsorbs impurities such as inorganic ions and organic substances contained in raw water.
Some organic substances such as humic substances among the adsorbed organic substances are irreversibly adsorbed on the strongly basic anion exchange resin,
Sodium hydroxide, which is a usual regenerant, is not desorbed but is gradually accumulated with an increase in the water-flow cycle, so that it is said that it has suffered a so-called organic contamination obstacle, and causes a decrease in anion exchange capacity.

[0004] Therefore, various methods have been proposed for desorbing the adsorbed organic substances by contacting the regenerant with a strongly basic anion exchange resin which has been damaged by organic substances. Examples of the regenerative agent include an aqueous solution of an inorganic salt such as sodium chloride, a mixed aqueous solution of an inorganic salt and a caustic alkali such as sodium hydroxide, an aqueous solution of an inorganic acid such as hydrochloric acid, and an aqueous solution of an oxidizing agent such as sodium hypochlorite. It is used. However, in the above method, organic substances adsorbed in the vicinity of the surface of the resin particles are relatively easily desorbed, but organic substances adsorbed in the internal pores of the resin particles are not easily desorbed.

[0005] Therefore, a method has been proposed in which a regenerative agent is heated and brought into contact with the regenerative agent in order to efficiently desorb organic substances adsorbed in the internal pores of the resin particles. However, in the above method, the heated regenerative agent may thermally decompose the exchange group of the strongly basic anion exchange resin. Moreover, conventionally,
For most strongly basic anion exchange resins, if at 50 ° C.
Even if a regenerative agent heated before and after is used, part of the organic matter remains in the internal pores of the resin particles, and the anion exchange ability cannot be sufficiently restored. Therefore, a simple and effective regenerative method has been required for a strongly basic anion exchange resin contaminated with organic substances.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a regenerating method for removing an organic substance from a strongly basic anion exchange resin, the method comprising the steps of: An object of the present invention is to provide a method for regenerating a strongly basic ion exchange resin which is excellent in the above.

[0007]

Means for Solving the Problems The present inventors have made various studies to achieve the above object, and as a result, a specific strong basic anion exchange resin was obtained by heating sodium chloride heated to 50 ° C. or more. It has been found that if the regeneration is carried out with an aqueous solution, the resin has an unexpected characteristic that the amount of organic substances remaining in the internal pores of the resin is small, and the present invention has been completed.

[0008] That is, the gist of the present invention is to provide a compound represented by the following general formula (I), which is subjected to desalting treatment to adsorb organic substances.
A method for regenerating a strongly basic anion exchange resin containing a structural unit having a quaternary ammonium base and a structural unit derived from an unsaturated hydrocarbon group-containing crosslinkable monomer,
A method for regenerating a strongly basic anion exchange resin, comprising contacting an aqueous solution of sodium chloride heated to 50 ° C. or higher with the strongly basic anion exchange resin to desorb adsorbed organic substances.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
First, the strongly basic anion exchange resin used in the present invention will be described. The anion exchange resin according to claim 1
And a structural unit having a quaternary ammonium salt group represented by the general formula (I) and a structural unit derived from an unsaturated hydrocarbon group-containing crosslinkable monomer.

In the general formula (I), A represents 3 to 8 carbon atoms.
Represents a linear alkylene group or an alkoxymethylene group having 4 to 9 carbon atoms. Examples of the linear alkylene group include a propylene group, a butylene group, a pentylene group, and a hexylene group. Examples of the alkoxy group include a butoxymethylene group and a pentoxymethylene group.

In the general formula (I), R ¹ represents an alkyl group having 1 to 4 carbon atoms which may be substituted by a hydroxyl group, and R ² and R ³ represent a hydrocarbon group having 1 to 4 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, a propylene group, and a butylene group.

In the general formula (I), X^-Is Ammoniu
Represents a counter ion coordinated to the
Is Cl^-, Br^-, I^-Halogen ions, sulfate ions, etc.
No, NO _Three ^-, OH^-, P-toluenesulfonic acid ion
And the like. And the anion is sulfated
When it is divalent, such as on, it is represented by the general formula (I)
One molecule of an anion binds to two molecules of the structural unit.
In addition, as the alkyl group of the substituent on the benzene ring, methyl
And a halogen atom.
Represents chlorine, bromine, iodine and the like.

In the general formula (I), R ² and R ³ are preferably a methyl group. Further, R ¹ is a methyl group, such as a trimethylammonium base (type I strong basic resin) or R ¹ is a hydroxyethyl group. Certain dimethylhydroxyethylammonium bases (type II strongly basic resins) are preferred.

As the unsaturated hydrocarbon group-containing crosslinking monomer, divinylbenzene, trivinylbenzene,
Examples thereof include divinyltoluene, divinylnaphthalene, divinylxylene, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate. Of these, divinylbenzene is preferred.

In the above strongly basic anion exchange resin, the ratio of the quaternary ammonium group represented by the general formula (I) to all anion exchange groups is preferably at least 90%, The total amount is the general formula (I)
Particularly preferred is a quaternary ammonium group represented by

The strongly basic anion exchange resin is, for example, a monomer obtained by reacting chloromethylstyrene with a polyalkylene dihalide having a polymethylene group having 3 to 8 carbon atoms by the Grignard method or vinylbenzyl alcohol with 1,1 a monomer having an alkoxymethylene group obtained by reaction with an ω-dihalogenoalkane (ω
-Halogenomethylstyrene) and divinylbenzene as a crosslinking agent.

The above-mentioned strongly basic anion exchange resin is disclosed, for example, in JP-A-4-349951 and JP-A-7-289.
921 is well known. However,
The above publication does not disclose a regeneration method for desorbing the organic substance adsorbed by the strongly basic anion exchange resin.

Next, the regeneration method of the present invention in which an aqueous solution of sodium chloride is brought into contact with a strongly basic anion exchange resin having adsorbed an organic substance will be described. The above-mentioned strong basic anion exchange resin is packed in an ion exchange tower, passed through raw water, adsorbs inorganic ions, organic substances, etc., and is subjected to a desalination treatment. When the passage of a predetermined amount of raw water is completed, most of the adsorbed inorganic ions and organic substances are desorbed.
The strongly basic anion exchange resin is subjected to a regeneration step using an aqueous sodium hydroxide solution as a regenerant.

By repeating the cycle of the step of passing water with raw water and the step of regenerating with an aqueous solution of sodium hydroxide, some organic substances such as humic substances that are not desorbed, for example, humic acid and fulvic acid, are removed from the strongly basic anion exchange resin. It gradually accumulates in the pores and causes anion exchange disorders such as a decrease in the purity of the treated water and an extreme decrease in the amount of water taken.

The regenerating method of the present invention comprises the steps of adding an aqueous solution of sodium chloride to a strongly basic anion exchange resin on which an organic substance is adsorbed.
It is an essential requirement that the contact be made by heating to 0 ° C. or higher. That is, the desorption effect of the organic substance adsorbed on the strongly basic anion exchange resin employed in the present invention is small when the temperature of the aqueous sodium chloride solution is lower than 50 ° C, and increases when the temperature of the aqueous sodium chloride solution is 50 ° C or higher. Although the upper limit temperature of the aqueous sodium chloride solution is not particularly limited, 97.5 ° C. is a standard.

The aqueous sodium chloride solution has a chloride ion having a high selectivity for a strongly basic anion exchange resin as an allion, does not generate an insoluble precipitate inside the ion exchange column, and is versatile and inexpensive. used. The concentration of the aqueous sodium chloride solution is not particularly limited, but may be 2 to 15%.
A range of weight% is preferred.

The aqueous sodium chloride solution may be usually an aqueous solution of sodium chloride alone. However, depending on the degree of contamination of organic substances or the nature of organic substances, sodium chloride and water-soluble organic solvents (methanol, ethanol, 1 selected from isopropyl alcohol)
A mixed aqueous solution may be used by adding more than one species, which is preferable because the dissociation degree of the contaminated organic matter is increased and the organic matter is desorbed. The mixing ratio of sodium chloride to sodium hydroxide, a water-soluble organic solvent, and the like is appropriately adjusted depending on the degree of the target organic contamination or the nature of the organic substance.

The method of filling the ion exchange tower with the strong basic anion exchange resin is a single bed method in which the anion exchange tower is filled alone, or the weak basic anion exchange resin and the strong basic anion exchange resin are stacked and charged. And a mixed bed method using a packed tower containing a strongly acidic cation exchange resin and a strongly basic anion exchange resin in a mixed state.

The regenerative operation in the present invention may be performed when an anion exchange failure which is considered to be caused by organic matter contamination occurs by repeating a cycle of a water passing process using raw water and a regeneration process using an aqueous sodium hydroxide solution. It may be performed periodically, for example, after several water passing steps are completed.

The strongly basic anion exchange resin subjected to the regenerating operation described above is subjected to a regeneration step using a regenerant such as an aqueous sodium hydroxide solution to exchange an anion exchange group into a hydroxyl ion type, and then to pure water again. Provided for manufacturing.

As described above, the regeneration method of the present invention can remove organic substances by applying the above-mentioned extremely simple regeneration step to a strongly basic anion exchange resin having a specific structure to which organic substances are adsorbed. River water,
It is possible to efficiently produce pure water such as boiler water, water for washing electronic materials, water for producing pharmaceuticals, water for producing cosmetics, and water for producing beverages and foods from raw water such as industrial water and clean water.

[0027]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Production Example <Synthesis of 4-bromobutylstyrene> In nitrogen-substituted diethyl ether, 100 parts by weight of chloromethylstyrene and 16.5 parts by weight of metallic magnesium were stirred at 10 ° C. for 3 hours to obtain a magnesium complex. Was. Next, after solvent replacement with nitrogen-substituted tetrahydrofuran, at 15 ° C.
463 parts by weight of 1,3-dibromopropane and Li ₂ C
Tetrahydrofuran 14 containing 4.4 parts by weight of uCl ₄
The magnesium complex was dropped into 42 parts by weight, and the reaction was performed at 15 ° C. for 5 hours.

Next, the obtained reaction solution was added to 0.3 Torr.
Distillation was carried out at 120 ° C. to obtain 55 parts by weight of 4-bromobutylstyrene. The identification of 4-bromobutylstyrene is described in "Journal of Polymer Science Polymer Chemistry Edition, Vol. 20, 198.
2 years, p. 3015 ".

<Synthesis of Crosslinked 4-Bromobutylstyrene Copolymer> 93.5 parts by weight of the above 4-bromobutylstyrene and 6.5 parts by weight of divinylbenzene having a purity of 80% by weight (the remaining main component is ethylvinylbenzene). Azobisisobutyronitrile (1.0 parts by weight) was added to
Suspension polymerization was performed at 0 ° C. for 18 hours to obtain a 4-bromobutylstyrene crosslinked copolymer granular material in a yield of 90% by weight.

<Synthesis of Strongly Basic Anion Exchange Resin> 100 parts by weight of the above crosslinked 4-bromobutylstyrene copolymer was stirred and suspended in 300 parts by weight of dioxane for 2 hours to swell. 30% by weight of 3 molar equivalents
An aqueous solution of trimethylamine was added dropwise, and the reaction was continued at 50 ° C. for 10 hours to obtain a strongly basic anion exchange resin. After sufficiently washing the obtained strongly basic anion exchange resin with demineralized water, the salt form was exchanged for a chlor form. As a result of measuring the general performance of the thus obtained strongly basic anion exchange resin, the neutral salt decomposition capacity was 1.27 meq / m1, 3.33.
meq / g and water content was 45.7% by weight.

Example 1 <Regeneration of Strongly Basic Anion Exchange Resin> 25 ml of the strongly basic anion exchange resin obtained in the above-mentioned preparation example was treated with an inner diameter of 14 m.
m, 4 wt% N after filling into a glass column 30 cm long
Regeneration was performed by passing 600 ml of an aOH aqueous solution. Then, after thoroughly washing with demineralized water, take out from the glass column,
Adhered water was removed using a centrifuge.

<Preparation of aqueous solution of humic acid> 100 mg of reagent humic acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 4% by weight of NaO
100 ml of H aqueous solution was added and stirred for 30 minutes. Then, a strongly acidic cation exchange resin that has been previously regenerated and exchanged into a hydrogen ion type (“Diaion S” manufactured by Mitsubishi Chemical Corporation)
KIB ") Inner diameter of 33 mm, length 2 filled with 150 ml
The aqueous solution was passed through a 5 cm glass column at a flow rate of 200 ml / h, and was further extruded with 300 ml of demineralized water. The absorbance in the cell was measured.

<Adsorption of Humic Acid by Strongly Basic Anion Exchange Resin> 400 ml of the aqueous humic acid solution prepared by the above method and 20 ml of the strongly basic anion exchange resin produced and regenerated by the above method are placed in a 1-liter Erlenmeyer flask. In addition, the mixture was shaken under the conditions of 20 ° C. and 80 rpm for 24 hours to adsorb humic acid to the strongly basic anion exchange resin. Then, No. After the strong basic anion exchange resin was filtered off with a 5C filter paper, the absorbance of the filtrate in a 254 nm, 10 mm cell was measured. The difference between the absorbance of the filtrate before and after the adsorption operation is 4
By multiplying by 00 ml and dividing by 20 ml of resin,
The apparent humic acid adsorption amount per unit resin amount was determined.

<Desorption of Adsorbed Humic Acid> The entire amount of the strongly basic anion exchange resin on which humic acid was adsorbed by the above method was thoroughly washed with demineralized water, and then adhering water was removed using a centrifuge. Next, a 300 ml Erlenmeyer flask 4
5 ml of the resin was separately collected into individual pieces, and 1
100 ml of a 0 wt% NaCl aqueous solution was added. 20 ° C,
Each Erlenmeyer flask was set on a constant temperature shaker set to 40 ° C., 60 ° C., or 80 ° C., and shaken at 80 rpm for 24 hours to desorb humic acid from the strongly basic anion exchange resin. Then, No. After filtering off the strongly basic anion exchange resin with a 5C filter paper, the filtrate was 254 nm, 10 m
The absorbance in the m cell was measured. The apparent absorbance per unit resin amount was obtained by multiplying the obtained absorbance by 100 ml of the regenerating agent and dividing by 5 ml of the resin amount. By dividing the obtained apparent desorption amount by the apparent adsorption amount obtained above, the desorption ratio of humic acid at each temperature was obtained. The desorption rate is shown in FIG.

COMPARATIVE EXAMPLE 1 Desorption of humic acid was carried out in the same manner as in Example 1 except that a strong basic anion exchange resin (manufactured by Mitsubishi Chemical Corporation, "Diaion SA10A") was used. The rate was determined. The desorption rate is shown in FIG.

[0037]

According to the regenerating method of the present invention, an organic substance is desorbed from a strongly basic anion exchange resin adsorbed with an organic substance by a very simple method by combining a specific regenerating method with a specific strongly basic anion exchange resin. Therefore, pure water can be efficiently produced.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the regeneration temperature of a strongly basic anion exchange resin and the desorption rate of humic acid.

Claims (3)

[Claims] 1. A structural unit having a quaternary ammonium group represented by the following general formula (I) and a structural unit derived from an unsaturated hydrocarbon group-containing crosslinkable monomer, which has been subjected to a desalting treatment to adsorb an organic substance. A method for regenerating a strongly basic anion exchange resin, comprising contacting an aqueous solution of sodium chloride heated to 50 ° C. or more with the strongly basic anion exchange resin to desorb adsorbed organic substances. A method for regenerating a strongly basic anion exchange resin. Embedded image (In the general formula (I), A represents a linear alkylene group having 3 to 8 carbon atoms or an alkoxymethylene group having 4 to 9 carbon atoms, and R ¹ has 1 to 4 carbon atoms which may be substituted with a hydroxyl group.
R ² and R ³ represent a hydrocarbon group having 1 to 4 carbon atoms; X ⁻ represents a counter ion coordinated to an ammonium group; or the benzene ring may be substituted with an alkyl group or a halogen atom. ) 2. Formula (I) for all anion exchange groups
The regeneration method according to claim 1, wherein a strongly basic anion exchange resin having a quaternary ammonium group ratio of 90% or more is used. 3. An aqueous solution of sodium chloride, wherein the aqueous solution of sodium chloride is selected from sodium hydroxide and a water-soluble organic solvent.
The regenerating method according to claim 1, wherein the regenerating method is a mixed aqueous solution to which seeds or more are added.