JPS625011B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a uranium ion adsorbent having high selectivity for uranium ions dissolved in water.

Materials that selectively adsorb uranium ions can be used not only for analysis, but also to help recover uranium ions emitted during the processing of uranium ore.
Furthermore, attention is being focused on selectively adsorbing and concentrating uranium ions that are dissolved in seawater in small amounts, and converting them into resources. In order to achieve these purposes, various properties such as high adsorption selectivity for uranium ions, chemical stability, economic efficiency, repeatability, complete water insolubility, and easy moldability are required. (Journal of the Atomic Energy Society of Japan, Vol. 22, 31 (1979))
reference).

Titanium oxide is an adsorbent that has been studied so far, especially for the purpose of collecting trace amounts of uranium in seawater. Although this adsorbent is highly economical and exhibits relatively good selective adsorption ability, it also has drawbacks such as non-negligible water solubility and difficulty in molding for actual use. , and its improvements are being considered. Systems using many organic adsorbents and living organisms, including other inorganic substances, have been attempted. Among them, many proposals have been made for organic polymer adsorbents because their chemical structures and physical properties can be selected arbitrarily. For example, polymer adsorbents with arsonic acid groups (Japanese Patent Laid-Open No.
51-99696), adsorbents with phenolic hydroxyl groups (JP-A-52-114510, JP-A-53-23889, JP-A-53
-26887, JP 53-26888), Carboxylic acid amide adsorbent (JP 50-134911, JP 1973-26888)
23890, JP-A-53-27690, JP-A-53-27692) have been proposed. Furthermore, it has been discovered that the amidoxime group exhibits excellent adsorption properties for uranium ions (Japanese Patent Application Laid-Open No. 126088/1983). Some of these have superior performance to titanium oxide, but require many manufacturing steps and have insufficient adsorption rates. In addition, adsorbents with amidoxime groups, which are considered to be excellent uranium adsorbents, have difficulty in repeated use because their adsorption-sensitive groups undergo hydrolysis and change, which is promoted by acids and alkalis. It turns out that.

On the other hand, a cyclic molecular structure that has the ability to adsorb uranium ions with high selectivity has been proposed, and its adsorption of uranium ions is being investigated (I.Tabushi et al.
al, J. Am. Chem. Soc., 102, 5948 (1980)), this synthesis is complicated and uneconomical.

In order to search for ligands that exhibit selective adsorption ability for uranium ions, the present inventor conducted detailed studies on many of these adsorbents, and as a result, the polydentate structure of organic polymers was determined. It was considered essential to introduce this into the Furthermore, as a result of examining the X-ray structure analysis of many uranium complexes, it was found that most of them have a planar pentacoordination structure, and the ligands that provide such a structure are effective in capturing uranium ions. Something was suggested. Based on this idea, the present inventors have conducted intensive research to solve the various problems of conventional uranium adsorbents as described above, and as a result, they have arrived at the present invention.

That is, the present invention is based on the general formula () (R in the formula represents a hydrogen atom or an alkyl group) and is obtained by reacting a hydrazone derivative of pyridine with a polymer having an acid anhydride structure.

General formula () The present invention relates to a uranium ion adsorbent characterized by having a ligand represented by (R in the formula has the same meaning as above) and a method for producing the same.

The hydrazone derivatives represented by the general formula () used in the present invention include hydrazones of 2-formylpyridine and 2-acetylpyridine, but a lower alkyl group may be introduced into the pyridine nucleus.

Polymers having an acid anhydride structure to be reacted with the hydrazone derivative represented by the general formula () include maleic anhydride and methyl vinyl ether,
Examples include copolymers of ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, hexyl vinyl ether, 2-methylpropene, styrene, polymers of itaconic anhydride, and polymers of acrylic anhydride. These polymers may be soluble, but in order to be used as a uranium adsorbent, it is desirable that they be insoluble in water, so these polymers should be crosslinked to make them insoluble before using them in the reaction. is appropriate. Examples of crosslinking agents for this purpose include ethylenediamine, triethylenediamine, pentamethylenediamine, hexamethylenediamine, phenylenediamine, m-phenylenediamine,
(4,4′-diamino)diphenylmethane, (4,
Diamines such as 4′-diamino)diphenyl ether, aminoethanol, diethanolamine,
Amino alcohols or polyhydric alcohols such as ethylene glycol, propylene glycol, glycerin, mannitol, and polyvinyl alcohol, as well as bishydrazides such as succinic acid bishydrazide and adipic acid bishydrazide, and bishydrazones such as glutaraldehyde and terephthaldialdehyde. I can do it. The amount of these crosslinking agents to be used is such that the amino group or hydroxyl group of the crosslinking agent is added in an amount of 0.01 to 0.50 equivalents to the acid anhydride unit.

The cross-linked and insolubilized acid anhydride structure used in the present invention can be molded into any form such as lumps, granules, films, and fibers, so it is easy to set the optimal conditions according to the purpose of use. You can.

In order to react these polymers with the hydrazone represented by the general formula (), the polymer is dissolved or suspended, and 1 to
Add 10 equivalents. Suitable solvents include tetrahydrofuran, dioxane, benzene, toluene, chloroform, and dimethylformamide. The reaction temperature is preferably from room temperature to the boiling point of the solvent used, and the reaction time is preferably 1 to 24 hours. Furthermore, in order to accelerate the reaction, it is effective to use a tertiary amine such as pyridine or triethylamine as a catalyst.

In order to adsorb uranium using the polymer having the ligand represented by the general formula () obtained in this way, it may be packed in a column if it is in the form of granules or blocks, or it may be packed in the form of a film or fiber. It may also be immersed in uranium-containing water in the form of uranium-containing water.

Furthermore, in order to increase the adsorption efficiency, the surface area of the polymer containing the ligand represented by the general formula () is increased by pulverizing it, molding it with a binder such as polyvinyl alcohol, and then heat-treating or chemical treatment. By doing so, it is effective to use any insoluble adsorbent.

According to the present invention, trace amounts of uranium ions are selectively adsorbed with high efficiency even if many other coexisting ions are present at high concentrations.

Such high adsorption efficiency is probably attributable to the fact that the ligand represented by the general formula () is tridentate. It is thought that the carboxyl groups present in the vicinity are also involved in the remaining two ligands necessary to capture the uranium ion.

In order to desorb uranium from the uranium adsorbent produced by the method of the present invention, an aqueous solution of carbonate is used, and regeneration can be performed under mild conditions. Therefore, damage to the ligand represented by the general formula () can be avoided as much as possible, so that it can be used repeatedly.

The method of the present invention can be applied not only to aqueous solutions with extremely low uranium concentrations of several ppb, such as seawater, but also to
It is suitable for adsorbing and separating uranium ions from an aqueous uranium solution with a high concentration of 100 ppm and concentrating it.
The adsorbent used here is inexpensive and has excellent economic efficiency. Therefore, the uranium scavenger of the present invention is suitable for industrial uses such as capturing uranium from seawater and recovering uranium from wastewater in uranium smelting, and its value is extremely high.

The present invention will be explained in more detail below based on examples, but the present invention is not limited to these explanations.

Example 1 5 g of 2-methylpropene-maleic anhydride copolymer (manufactured by Clareisoprene Chemical Co., Ltd., Isoban, molecular weight 16-17×10 ⁴ ) was added to 30 cm ² of a mixed solvent of dimethylformamide and tetrahydrofuran (1:1).
0.17 g of p-phenylenediamine dissolved in 1 cm ² of dimethylformamide was mixed,
After stirring for several minutes, this was spread on a glass plate to form a film. After drying at room temperature for 30 minutes, this was immersed in acetone for one day and then vacuum dried to obtain a crosslinked product of 2-methylpropene-maleic anhydride copolymer.

To 2.3 g of this cross-linked insolubilized 2-methylpropene-maleic anhydride copolymer, 2.19 g of pyridine-2-aldehyde hydrazone and triethylamine.
1.82 g was added, and further dioxane was added until the crosslinked and insolubilized maleic anhydride copolymer film was completely immersed, and the mixture was stirred at room temperature for 7 days.

Thereafter, this membrane was washed with water and vacuum dried to obtain an adsorbent having a pyridine-2-aldehyde hydrazone derivative in its side chain.

This structure was confirmed by showing the infrared absorption spectrum of the amide group at 1640 cm ^-1 . Elemental analysis also revealed that it contains 6.57% by weight of nitrogen, and 30% of the carboxylic acid anhydride is pyridine-2-
This means that it reacted with aldehyde hydrazone.

240 mg of the adsorbent obtained here was ground into 60 meshes in a mortar, mixed with 3 ml of a warm aqueous solution of 250 mg of fully saponified polyvinyl alcohol, and this viscous aqueous solution was poured onto an acrylic plate and air-dried to form a transparent film. did. This film was treated at 110° C. for 1 hour to make it crosslinked and insolubilized.

The film obtained in this way is packed into a column, and the flow rate is
Seawater (collected from the Oarai coast) was passed through the tube at a rate of 20 cm ² /hr for 7 days. After washing the film with water, it was immersed in 10 cm ² of a 3% ammonium carbonate aqueous solution and heated to 40° C. for 24 hours. After separating the films, the amount of uranium contained in the ammonium carbonate aqueous solution was measured by fluorescence analysis using a flux consisting of sodium carbonate, potassium carbonate, and sodium fluoride. Ammonium carbonate aqueous solution 10cm ²
It was found that 1.0μg of uranium was desorbed and present inside. In other words, 4.3 μg of uranium is adsorbed in terms of gram of adsorbent. 3μg/in seawater
If it contains 17% of the uranium in the seawater that passed through it, that means that 17% of the uranium was collected. For comparison, when uranium was collected from seawater under similar conditions using titanium dioxide insolubilized with fully saponified polyvinyl alcohol, 5.8 μg of uranium was adsorbed in terms of 1 g of adsorbent. This indicates that the adsorbent having a pyridine-2-aldehyde hydrazone derivative in its side chain has a trapping ability comparable to that of titanium dioxide.

Example 2 In the same manner as in Example 1, 1.16 g of 2-methylpropene-maleic anhydride copolymer crosslinked and insolubilized with phenylene diamine and 1.56 g of methyl-2-pyridylketone hydrazone were mixed with 0.91 g of triethylamine.
was stirred for 7 days in dioxane using as a catalyst to obtain an adsorbent having a methyl-2-pyridylketone hydrazone derivative in its side chain.

This structure was confirmed by showing the infrared absorption spectrum of the amide group at 1.640 cm ^-1 . Elemental analysis revealed that it contained 4.71% by weight of nitrogen, which means that 20% of the carboxylic acid anhydride had reacted with the methyl-2-pyridylketone hydrazone.

500 mg of the adsorbent obtained here was added to 60 mg in the same manner as in Example 1.
It was made into powdered mesh and sealed in a polyvinyl alcohol film. This film was packed in a column, and seawater was passed through it at a flow rate of 20 cm ² /hr for 7 days, and then, as in Example 1, it was immersed in an aqueous ammonium carbonate solution to desorb the uranium adsorbed by the adsorbent. The uranium inside was measured using fluorescence analysis. 4.4 μg of uranium was adsorbed per gram of adsorbent. This means that 38% of the uranium in the seawater was collected.

As shown in Example 1, titanium dioxide adsorbed 5.8 μg of uranium in terms of gram of adsorbent under the same conditions. This shows that the adsorbent having a methyl-2-pyridineketone hydrazone derivative in its side chain has a collection ability comparable to that of titanium dioxide.

Claims (1)

[Claims] 1 (In the formula, R represents a hydrogen atom or an alkyl group.) A uranium adsorbent comprising a copolymer having an acylhydrazone structure represented by the following formula and a carboxyl group in the side chain. 2 General formula (In the formula, R represents a hydrogen atom or an alkyl group.) A general formula characterized by reacting a hydrazone represented by the following with a copolymer of maleic anhydride and a vinyl monomer: (In the formula, R has the same meaning as above.) A method for producing a uranium adsorbent comprising a copolymer having an acylhydrazone structure represented by the following and a carboxyl group in the side chain.