JP2003071280A - Heavy metal ion adsorbent and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a novel heavy metal ion adsorbent obtained by fixing a metal trapping group to a matrix resin and capable of selectively adsorbing heavy metal ions to take in them stably. SOLUTION: The heavy metal ion adsorbent comprises a reaction product of a linear copolymer having a maleic anhydride unit bonded to a porous synthetic resin through an amino group and a chelate forming compound having an amino group. This heavy metal ion adsorbent is manufactured by aminating the porous synthetic resin and subsequently the linear copolymer having the maleic anhydride unit is reacted with the aminated porous synthetic resin to form a chemical bond between the amino group in the porous synthetic resin and a part of the maleic anhydride unit and reacting the chelate forming compound having an amino group of the reaction product to introduce a chelate forming group into the obtained reaction product.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel heavy metal ion adsorbent that selectively adsorbs heavy metal ions, and a method for efficiently producing the same.

[0002]

2. Description of the Related Art Many chelate resins have been developed as materials for selectively adsorbing heavy metal ions, and resins containing iminodiacetic acid residues or alkylpolyamine residues as their chelate-forming groups have been commercially available. There is.

The adsorption selectivity of the metal ion in the chelate resin is exerted mainly on the basis of the selective complex formation of the metal capturing group fixed to the resin, that is, the chelate forming group. However, the conventional chelating resins generally have a metal capturing group fixed to a rigid crosslinked polymer compound, and thus have a drawback that the capturing group has a low degree of freedom and the selectivity of the capturing group is not sufficiently exhibited. .

In order to improve this drawback, it has been proposed so far that, for example, a spacer is introduced between the metal capturing group and the base polymer compound to secure the degree of freedom of the capturing group (patent). No. 1798191). However, in this case, various problems are involved in the synthesis when the spacer is introduced, and the chelate resin has a bidentate ligand and a tridentate ligand.
Many of them have a bidentate ligand as a trapping group, and there is a drawback that the number of bonding atoms is insufficient to trap a hexacoordinated metal ion.

As described above, in the chelate resin, since the metal capturing group is fixed to the rigid resin, it is difficult to form a 1: 2 or 1: 3 complex with a metal ion as in a homogeneous solution. Therefore, for example, a reagent-impregnated resin in which a hydrophobic reagent is impregnated and held in a porous resin has been developed.
Since the impregnated reagent is not fixed to the high molecular compound of the base material, it can form a 1: 2, 1: 3 complex, but the reagent is inevitably eluted from the base material.

On the other hand, natural ferrioxamine B is a linear molecule having a metal ion binding site, and it is known that the shape of the linear molecule is changed according to the metal ion and the metal ion is stably encapsulated. Has been.

[0007]

Under the above circumstances, the present invention is a resin in which a metal-trapping group is fixed to a base resin, and selectively adsorbs heavy metal ions and stably takes them in. The purpose of the present invention is to provide a novel heavy metal ion adsorbent that can be used.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to develop a novel heavy metal adsorbent having a chelate-forming group as a metal-trapping group, and first, the selectivity of the adsorbent is sufficiently exhibited. In order to achieve this, the metal scavenging group maintains a high degree of freedom in the matrix resin phase, that is, the steric degree of freedom in which the metal scavenging group can bond to a metal ion is equivalent to the complex forming reaction in a homogeneous solution. Focusing on the importance of holding, a certain kind of linear copolymer is fixed to the porous synthetic resin, and if a metal ion-trapping group is introduced into the copolymer, the porous synthetic resin Based on this finding, we found that a highly selective heavy metal ion adsorbent that can change the shape of the linear copolymer by free movement inside the voids of the The invention was completed.

That is, the present invention comprises a reaction product of a linear copolymer having a maleic anhydride unit bonded to a porous synthetic resin via an amino group and a chelate-forming compound having an amino group. A heavy metal ion adsorbent and a porous synthetic resin are aminated, and then a linear copolymer having a maleic anhydride unit is reacted to form a space between the amino group in the porous synthetic resin and a part of the maleic anhydride unit. The present invention provides a heavy metal ion adsorbent characterized by introducing a chelate-forming group by reacting a chelate-forming compound having an amino group after forming a chemical bond with.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the heavy metal ion adsorbent of the present invention, a porous synthetic resin is used as the base material resin. The porous synthetic resin is not particularly limited,
For example, a porous synthetic resin produced by molding a synthetic resin mixed with an easily soluble filler and then eluting the filler can be used. Among such porous synthetic resins, porous crosslinked polyacrylic acid ester resin and porous crosslinked polystyrene resin are particularly preferable.
The porous synthetic resin has a specific surface area of 5
0-800 m ² / g, average pore size 1-10 nm, particle size 20
The range of up to 200 mesh is preferable.

On the other hand, the linear copolymer having a maleic anhydride unit bonded to the porous synthetic resin via an amino group is preferably an alternating copolymer of maleic anhydride and a vinyl monomer. Further, if the molecular weight is too large, the solubility in a solvent will be poor, and there is a risk of inconvenience in the introduction reaction into the porous synthetic resin. If the molecular weight is too small, changes in shape due to free movement cannot be expected. Therefore, the preferable molecular weight is 1,000 to 1,000 in terms of weight average molecular weight.
It is about 200,000.

The vinyl monomer copolymerized with maleic anhydride is not particularly limited, but a monomer having a hydrophilic group such as a methoxy group or a carboxyl group is preferable. Examples of such vinyl monomers include methyl vinyl ether, acrylic acid, methacrylic acid and the like.
These may be used alone or in combination of two or more.

The heavy metal ion adsorbent of the present invention comprises the above-mentioned linear polymer copolymer bound to the porous synthetic resin, which is the above-mentioned base material resin, via an amino group, and further forms a chelate having an amino group. And a chelate-forming compound having an amino group capable of reacting with the maleic anhydride unit of the linear copolymer, and having a functional group capable of forming a chelate. There is no particular limitation as long as it is available.

As the functional group having the ability to form a chelate, those having an oxygen ligand, those having a nitrogen ligand, those having a sulfur ligand, phosphoric acid derivative residues, polysaccharide residues, proteins Residues are known. Among these, those having an oxygen ligand include, for example, residues such as aliphatic diols, hydroxyketones, polycarbonyls, aromatic polyhydroxy compounds, aromatic hydroxycarbonyls and polycarboxylic acids, and nitrogen ligands. As those having a residue of an aliphatic or aromatic amine, oxime, Schiff base, porphyrin, peptide, amino alcohol, amino acid, aminophenol, nitrogen-containing heterocyclic compound, azo compound, aminopolycarboxylic acid, etc. Examples of those having a ligand include residues such as thioalcohol, thiophenol, thioketone, dithiolate, thioamide and thiourea. It is preferable that the functional group having the ability to form a chelate be appropriately selected and used according to the kind of the heavy metal ion to be captured, which has the highest tendency to form a chelate.

In such a heavy metal ion adsorbent, since the metal-trapping group is on the linear copolymer fixed on the surface of the porous synthetic resin, the steric degree of freedom is high and the main component of the linear copolymer is high. The chains can change shape to surround and trap heavy metal ions.

According to the method of the present invention, the heavy metal ion adsorbent can be efficiently produced as described below. In the method of the present invention, the surface of the above-mentioned porous synthetic resin is first aminated. The aminating agent is not particularly limited as long as it is capable of reacting with the porous synthetic resin and forming an amino group capable of reacting with the maleic anhydride in the resin. As such an aminating agent,
Examples thereof include ethylenediamine, diethylenetriamine, triethylenetetramine, phenylenediamine, and the like. Among these, ethylenediamine and diethylenetriamine are particularly preferable.

When the base material resin is a porous crosslinked polyacrylic acid ester resin, an amide bond is formed by heating the resin together with a solution containing the above amine, and an amination treatment is achieved. If the base material resin is a porous cross-linked polystyrene resin, it may be aminated through chloromethylation.

Next, the aminated porous synthetic resin is reacted with the linear copolymer having a maleic anhydride unit to give one of the amino group and maleic anhydride unit in the porous synthetic resin. A chemical bond is formed with the part. In this reaction, for example, a linear copolymer having a maleic anhydride unit is dissolved in an appropriate organic solvent such as acetonitrile, an aminated dry porous synthetic resin is added to this solution, and then the solvent is distilled off under reduced pressure. It is achieved by

By this operation, a part of the maleic anhydride unit of the linear copolymer rapidly reacts with the amino group on the surface of the porous synthetic resin, and the linear copolymer is mediated by the amino group according to the following reaction formula. Bonded to the porous synthetic resin.

[0020]

[Chemical 1]

By this reaction, most of the maleic anhydride unit in the linear copolymer remains, so by reacting the above chelate-forming compound having an amino group,
A chelate-forming group can be easily introduced. As a chelate-forming compound having an amino group, hydroxylamine (H ₂ NOH), cysteamine (H ₂ NCH ₂ CH ₂
An example of introducing a metal-trapping group by using each of (SN) is shown in the following reaction formula.

[0022]

[Chemical 2]

In this way, the heavy metal ion adsorbent of the present invention can be efficiently produced.

[0024]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 (1) Amination of porous crosslinked polyacrylic acid resin In 500 ml of dioxane, 85 g of diethylenetriamine was added.
Was dissolved, 150 g of porous crosslinked polyacrylic acid resin which had been washed and dried in advance was added thereto, and the mixture was heated under reflux for 12 hours while stirring. Then, the aminated porous resin was washed with dioxane and then dried. As a result of analysis, it was estimated that this aminated porous resin contained 0.7% by mass of nitrogen, and therefore 0.17 mol of diethylenetriamine was introduced.

(2) Introduction of linear copolymer To a solution prepared by dissolving 80 g of a linear alternating copolymer of methoxyvinyl and maleic anhydride in 500 ml of acetonitrile,
The aminated porous resin obtained in (1) above was added and stirred for 3 hours at room temperature. Then, acetonitrile was distilled off under reduced pressure, and the residue was washed with 150 ml of a dioxane / acetonitrile mixed solution (volume ratio 2/1) to remove an extra linear alternating copolymer.

(3) Introduction of hydroxamic acid as metal-trapping group Hydroxylamine hydrochloride 1 in 500 ml of hot methanol
After 32 g was dissolved and 400 ml of a methanol solution containing 155 g of potassium hydroxide was added, the mixture was cooled to room temperature and the formed potassium chloride precipitate was removed by filtration. The porous resin containing the linear copolymer obtained in (2) above was added to this filtrate, and the mixture was stirred at room temperature for 2 days. The resin was then filtered, thoroughly washed with 1 mol / liter hydrochloric acid, 1 mol / liter sodium hydroxide aqueous solution, and then with water to remove unreacted substances, and dried. As a result of analysis, this product had a nitrogen content of 2.8% by mass, and therefore, it is estimated that about 1.5 mmol of hydroxamic acid was introduced into 1 g of the dry resin.

Example 2 Cysteamine hydrochloride 67.4 in 300 ml of hot methanol
g was dissolved, 400 ml of a methanol solution containing 124 g of potassium hydroxide was added, and then cooled to room temperature,
The formed potassium chloride precipitate was removed by filtration.
To this filtrate, the porous resin having the linear copolymer obtained in (2) of Example 1 was added, and the mixture was stirred at room temperature for 2 days.
The resin was then filtered, washed thoroughly with water to remove unreacted material and dried. As a result of analysis, this product had a nitrogen content of 1.66% by mass, and therefore it is estimated that about 0.7 mmol of cysteamine was introduced into 1 g of the dry resin.

Application Example 1 Resin 50 having cysteamine residue obtained in Example 2
To 0 mg, 50 ml of an aqueous solution of cadmium having various pHs (cadmium content: 2 mmol) was added and allowed to infiltrate for 5 days,
The residual cadmium concentration was measured to determine the cadmium ion removal rate. The relationship between the cadmium ion removal rate and pH is shown in a graph in FIG. As you can see from this graph,
Cadmium was quantitatively removed under conditions of pH 6 or higher.
Also, the base material resin itself had almost no ability to adsorb cadmium.

Application Example 2 Resin 50 having cysteamine residue obtained in Example 2
To 0 mg, 50 ml of a cadmium aqueous solution of various pH (cadmium content 20 mmol) was added, and the mixture was allowed to penetrate for 5 days, the residual cadmium concentration was measured, and the adsorbed amount of cadmium ions was determined. The relationship between the amount of adsorbed cadmium ions and pH is shown in a graph in FIG. As is clear from this graph, 0.4 to 0.
5 mmol of cadmium ions were adsorbed.

[0031]

INDUSTRIAL APPLICABILITY The heavy metal ion adsorbent of the present invention has a high degree of steric freedom of the metal-trapping group, and the main chain of the linear copolymer can change its shape to surround and trap heavy metal ions. It excels in selective adsorption of ions and can stably take in the heavy metal ions.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the cadmium ion removal rate and pH in Application Example 1.

FIG. 2 is a graph showing the relationship between the amount of adsorbed cadmium ions and pH in Application Example 2.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4G066 AB10A AB15B AC14A AC17A                       AD10A CA46 DA08 FA07                 4J031 AA16 AA20 AA24 AB02 AC07                       AD01 AF08 CD14                 4J100 AE03P AK32Q AL03P BA03H                       BA28H BA33H BA34H BA52H                       HA61 HB42 HC70 HE14 JA15                       JA18

Claims (2)

[Claims] 1. A heavy metal ion adsorbent comprising a reaction product of a linear copolymer having a maleic anhydride unit bonded to a porous synthetic resin via an amino group and a chelate-forming compound having an amino group. . 2. A porous synthetic resin is aminated, and then a linear copolymer having a maleic anhydride unit is allowed to react, whereby an amino group in the porous synthetic resin and a part of the maleic anhydride unit are reacted. A method for producing a heavy metal ion adsorbent, which comprises forming a chemical bond and then introducing a chelate-forming group by reacting a chelate-forming compound having an amino group.