JPH0533246B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a chelate resin and a method for producing the same.

Since chelate resins can selectively separate and recover metal ions from metal ion solutions, they are useful for purification of industrial water, wastewater treatment, recovery of rare metals, and the like.

[Prior art]

Conventionally, a resin having an amidoxime group has been produced by reacting a resin having a nitrile group with hydroxylamine, and the resin thus obtained has been used to react with heavy metals such as gold, iron, mercury, silver, lead, and copper. It is known that it has good adsorption properties against (see JP-A-51-53593 and JP-A-53-126088). However, this resin has the drawback of slow adsorption speed, and in order to improve this drawback, cross-linked resins selected from the group consisting of polyacrylates and polymethacrylates of polyalkylene polyols in which the alkylene group has 2 to 4 carbon atoms are used. By polymerizing a monomer mixture containing an ethylenically unsaturated compound having an amidoxime group and an ethylenically unsaturated compound having a nitrile group, and reacting the resulting polymer with hydroxylamine, the polymer has an amidoxime group and adsorbs heavy metals at a high rate. A method for producing a resin that can be used has been proposed. (JP-A-56
-53106). Although this improved chelate resin has an improved adsorption rate of metal ions compared to conventional resins having amidoxime groups, it is not necessarily fully satisfactory. Therefore, in order to adsorb a large amount of a dilute metal ion-containing liquid, the processing cost per unit time is small, the processing equipment becomes large, and there are drawbacks such as increased construction costs and working capital.

[Purpose of the invention]

An object of the present invention is to provide a method for producing a chelate resin that has a higher metal ion adsorption rate than the conventional method.

According to the present invention, an ethylenically unsaturated compound having a nitrile group and a crosslinking agent are suspended in an aqueous medium in the presence of a good solvent and a poor solvent, and then the obtained copolymer is produced. This is achieved by amidoximating the polymer.

[Structure of the invention]

The present invention relates to an improvement in a known method for producing a resin having an amidoxime group, and when producing a copolymer having a nitrile group as an intermediate,
The resin is produced according to a known method except that both a good solvent and a poor solvent are used in combination.

That is, the gist of the present invention is a method for producing a chelate resin in which an ethylenically unsaturated compound having a nitrile group and a crosslinking agent are polymerized, and then the resulting copolymer is converted into an amidoxime. A good solvent that swells the volume of the copolymer by 1.40 times or more and a poor solvent that does not swell the volume of the obtained copolymer by 1.30 times or more are used in an unsaturated compound in which the weight ratio of the good solvent to the poor solvent is 0.2 to 30. A method for producing a chelate resin characterized by carrying out suspension polymerization in an aqueous medium in which the weight ratio of the total amount of a poor solvent and a good solvent to the total amount of monomers including a crosslinking agent and a crosslinking agent is 0.1 to 5. exists in

The present invention will be explained in detail below.

As the ethylenically unsaturated compound having a nitrile group, acrylonitrile, methacrylonitrile, chloroacrylonitrile, vinylidene cyanide, crotonitrile, 2-cyanoethyl acrylate, 2-cyanoethyl methacrylate, etc. are used. Usually acrylonitrile or methacrylonitrile is used. Two or more of these nitriles may be used in combination. Nitriles usually represent 10-90% (by weight) of the monomers, preferably 40-80% (by weight).

Examples of crosslinking agents include polyvinyl aromatic compounds such as divinylbenzene, trivinylbenzene, divinyltoluene, and divinylxylene, polyvinyl heterocyclic compounds such as divinylpyridine, and polyvinyl ester compounds such as ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate. A compound having two or more radical polymerization-active double bonds is used. Usually divinylbenzene, trivinylbenzene, divinylnaphthalene, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate or tetraethylene glycol dimethacrylate is used.
These crosslinking agents may be used in combination of two or more. The crosslinking agent usually accounts for 90-10% (by weight) of the monomer,
Preferably it accounts for 60-20% (by weight).

A good solvent is a compound that swells the volume of a crosslinked copolymer obtained by copolymerizing an ethylenically unsaturated compound having a nitrile group and a crosslinking agent by 1.40 times or more,
For example, dialkylcarboxamides such as dimethylacetamide and dimethylformamide, sulfoxides such as dimethylsulfoxide and diethylsulfoxide, sulfones such as dimethylsulfone and diethylsulfone, carbonates such as ethylene carbonate and propylene carbonate, nitrophenols, Halogenated solvents such as γ-butyrolactones, dichloroethanes, and carbon tetrachloride, and phthalic acid esters such as dimethyl phthalate and diethyl phthalate are used. Usually dimethyl phthalate, diethyl phthalate, 1,2-dichloroethane or carbon tetrachloride are used. Two or more of these good solvents may be used in combination.

The poor solvent is a suitable compound that does not swell the crosslinked copolymer obtained by copolymerizing an ethylenically unsaturated compound having a nitrile group with a crosslinking agent by more than 1.30 times, such as toluene, aromatic compounds such as benzene, ethyl acetate, etc. , aliphatic carboxylic acid ester compounds such as butyl acetate, isoamyl alcohol,
Alcohols such as methyl isobutyl carbinol and saturated hydrocarbons such as n-heptane and isooctane are used. Usually toluene or n-
Heptane is used. Two or more of these poor solvents may be used in combination.

The weight ratio of the good solvent to the poor solvent is 0.2 to 30, and the weight ratio of the total amount of the good solvent and the poor solvent to the total amount of the monomer including the ethylenically unsaturated compound having a nitrile group and the crosslinking agent is 0.1 to 5. be.

When producing a copolymer having a nitrile group in the present invention, in addition to the above-mentioned ethylenically unsaturated compound having a nitrile group and a crosslinking agent, other monomers that can be copolymerized with these, such as styrene, acrylic It is also possible to coexist with an acid or the like.

A mixture of an ethylenically unsaturated compound having a nitrile group, a crosslinking agent, a good solvent, and a poor solvent is polymerized according to a known method. Usually, a polymerization initiator such as benzoyl peroxide is dissolved in a mixed solution of the four components and then dispersed in water to produce spherical particles. It is preferable to add a dispersion stabilizer such as polyvinyl alcohol, gelatin, or carboxymethyl cellulose to water, which is a dispersion medium.

Further, it is preferable that a water-soluble salt such as sodium chloride, calcium chloride, sodium sulfate, etc. be present at the same time to prevent the monomer from dissolving in water.

A copolymer having a nitrile group is reacted with hydroxylamine by a conventional method to convert the nitrile group into an amidoxime group. Usually, the above nitrile group-containing copolymer is added to a water or methanol solution of hydroxylamine, and the reaction is carried out by heating at 40 to 100°C for several hours to over ten hours. The amount of hydroxylamine may generally be equimolar to the nitrile.

The amidoxime group-containing resin obtained by the method of the present invention exhibits a higher adsorption rate for heavy metals than known resins, and is therefore useful as various heavy metal adsorbents.

〔Example〕

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

Example 1 A Synthesis of resin Polyethylene glycol (average molecular weight 200)
A mixed solution of 13 g of dimethacrylate, 27 g of divinylbenzene with a purity of 56.5%, 60 g of acrylonitrile, 50 g of carbon tetrachloride as a good solvent, 70 g of toluene as a poor solvent, and 1 g of benzoyl peroxide,
The suspension was suspended in 750 ml of water containing 1.25 g of polyvinyl alcohol, and heated and stirred at 70° C. for 8 hours.
After cooling to room temperature, strain and rinse thoroughly with water.
It was dried with ventilation at 80°C for 8 hours. Particle size approximately 300~
90g of 1000μ spherical particles were obtained.

Add 50g of the above resin to 0.5g of hydroxylamine.
into 500 ml of methanol solution containing mol,
The reaction was carried out at 60° C. for 6 hours while stirring.

After cooling to room temperature, it was washed with water until hydroxylamine was no longer detected. 220 ml of wet resin with amidoxime groups were obtained.

B Measurement of adsorption capacity A part of the above resin was placed under reduced pressure of 1 mmHg or less.
It was dried at 50°C for 8 hours. Approximately 2 g of the dried resin was accurately weighed, added to 250 ml of 0.05M copper chloride solution, and left overnight at 25° C. with occasional stirring. Take 2 ml of this supernatant liquid with a whole pipette, and
The copper adsorption capacity of the resin was determined to be 2.6 mmol/g by titration with a 100 MEDTA solution.

C Measurement of adsorption rate Adjust the above resin to 5 ml in a wet state, pH 4.3, 0.01 mol/cupric chloride (acetic acid-
Each was added to an Erlenmeyer flask containing 100 ml of sodium acetate buffer.

The Erlenmeyer flask containing the resin was shaken at a temperature of 25℃ using a shaker with a shaking speed of 100 times per minute and a shaking width of 20cm to determine the amount of copper ions adsorbed to the resin.
Measurement was performed over time using the EDTA method to examine the increase in adsorption rate to functional groups in the resin. The results are shown in solid line a in FIG.

Example 2 Example 1 except that 22 g of polyethylene glycol (average molecular weight 200) dimethacrylate was used as a crosslinking agent, 18 g of divinylbenzene with a purity of 56.5%, 75 g of 1,2-dichloroethane as a good solvent, and 40 g of n-heptane as a poor solvent. Similarly,
Resins with amidoxime groups were produced, and the copper adsorption capacity and adsorption rate were measured. 205 ml of wet resin was obtained. The copper adsorption capacity of this resin is
It was 2.07 mmol/g. The copper adsorption rate is shown by the solid line b in FIG.

Example 3 As a good solvent, 125 g of 1,2-dichloroethane,
A resin having an amidoxime group was produced in the same manner as in Example 2, except that 15 g of n-heptane was used as a poor solvent, and the copper adsorption capacity and adsorption rate were measured. 160ml of wet resin was obtained. The copper adsorption capacity of this resin was 2.64 mmol/g. The copper adsorption rate is shown by solid line c in FIG.

Comparative Example 1 The copper adsorption rate of a commercially available amidoxime type chelate resin (Diaion CR50 manufactured by Mitsubishi Chemical Industries, Ltd.) was measured in the same manner as in Example 1. The results are shown in broken line d in FIG.

〔Effect of the invention〕

From Examples 1 to 3 and Comparative Example 1, copolymers obtained by suspension polymerization using a mixture of an ethylenically unsaturated compound having a nitrile group according to the method of the present invention, a crosslinking agent, and a good solvent and a poor solvent It is clear that the chelate resin obtained by converting into amidoxime has a higher metal ion adsorption rate than the chelate resin having an amidoxime group produced by a known method, and is very useful industrially. be.

[Brief explanation of the drawing]

FIG. 1 is a graph showing changes over time in the adsorption rate of copper ions by the chelate resins of the present invention obtained in Examples 1 to 3. The vertical axis represents the adsorption rate of copper ions on the chelate resin (the adsorption amount divided by the equilibrium adsorption amount), and the horizontal axis represents the adsorption time during which the shaker is operated. In the figure, solid lines a to c are the results obtained using the chelate resins of the present invention in Examples 1, 2, and 3, respectively, and a broken line d is the results obtained using the commercially available amidoxime type resin (Diaion CR50 manufactured by Mitsubishi Kasei).

Claims (1)

[Claims] 1. In a method for producing a chelate resin in which an ethylenically unsaturated compound having a nitrile group and a crosslinking agent are polymerized and then the resulting copolymer is converted into an amidoxime, the polymerization is carried out by controlling the volume of the resulting copolymer.
A good solvent that causes the volume of the resulting copolymer to swell by 1.40 times or more, and a poor solvent that does not cause the resulting copolymer to swell by 1.30 times or more in volume.
An aqueous solvent in which the weight ratio of the good solvent to the poor solvent is 0.2 to 30, and the weight ratio of the total amount of the poor solvent and the good solvent to the total amount of the monomer including the unsaturated compound and the crosslinking agent is 0.1 to 5. A method for producing a chelate resin, which comprises carrying out suspension polymerization in a medium.