JPH0675674B2 - Uranium adsorbent - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel uranium adsorbent.

(Prior art) Utilization of various types of energy such as nuclear power, hydraulic power, wind power, tidal power, etc. as alternative energy to petroleum is being considered, but what is superior to nuclear power in terms of its technical perfection, cost and output, etc. Absent.

On the other hand, the amount of uranium reserves on land, which is a fuel for nuclear energy, is estimated to be 5 million tons, which is not enough for future demand. However, in seawater,
Although it is a very dilute concentration of ppb, there is a huge amount of uranium with a total amount of 4.2 billion tons. The technology for recovering uranium from seawater has been earnestly studied as an extremely important technology, but a sufficient adsorbent has not yet been found.

Requirements for the uranium adsorbent are that it has a large association constant with uranium and that it has excellent selective adsorption of uranium to other metal ions.

Many uranium adsorbents have been proposed so far, and representative ones are potassium titanate, amidoxime resin, crown ether compounds, etc., but the fact that they do not meet the above-mentioned requirements and cost , Regeneration of adsorbent
There were problems in terms of reusability and handling.
Also, a report by Zinke et al. In 1941 (Ber.dtsch.Chem.Ges., 74
1729 (1941)) and Cornforth et al. (Brit.J.Ph
armacol., 10 73 (1955)), Kmmerer et al. (Makromol.Ch
em., 162 179 (1972)), Munch (Makromol.Chem. 178 6
9 (1977)) and Gutsche et al. (J. Am. Chem. Soc. 103 3782).
(1981)) and the like show the synthesis of various calixarene derivatives which are cylindrical compounds composed of a benzene ring. However, none of the obtained calixarene derivatives is water-soluble, but there is a problem that the water-solubility is poor (of course, there is no description about a uranium adsorbent from seawater).

The present inventors have thoroughly examined the drawbacks of the prior art, and have performed a sufficient analysis of the uranium existing form in seawater, and found that uranium in seawater is ▲ UO ₂ (CO ₃ ) ⁴ _-3 ▼ Stable in the form of a complex, and the coordination structure of the uranyl ion ▲ UO ²⁺ ₂ ▼ has a coplanar hexacoordinated structure, which is a tetrahedral coordination structure of other metal ions. This is a big difference from the tetrahedral structure. By utilizing this fact, it was found that it is possible to produce a uranium adsorbent having excellent selectivity and association constant for uranium, and first, a uranium adsorbent of a calixarene derivative having a specific ring structure and chemical structure was prepared. Proposed.

However, since this calixarene derivative is water-soluble,
For example, it is difficult to apply to the practical process of uranium adsorption-concentration-desorption from seawater or wastewater, and the workability is poor.

(Problems to be Solved by the Invention) As a result of intensive studies, the present inventors have reached the present invention. That is, an object of the present invention is to propose a uranium adsorbent in which the above-mentioned calixarene derivative is immobilized on a resin without impairing the property of excellent selective adsorption of uranium.

(Means for Solving Problems) The present invention is a uranium adsorbent comprising a resin having a calixarene derivative represented by the following general formula (I) immobilized thereon.

However, n: 4 to 10 R: hydrogen, lower alkyl group, lower alkyl carboxylic acid or salt thereof, unsaturated alkyl group or aromatic hydrocarbon x, y: hydrogen, alkyl group, aromatic hydrocarbon z: SO ₃ M, NO ₂ , NH ₂ , COOM ′, OM ″, OR ′ M, M ′, M ″: hydrogen, ammonium ion, lower alkylammonium ion, metal ion R ′: hydrogen, R ″ OH, R ″ COOH, R "NO ₂ , R" NH ₂ ,
R ″ SO ₃ M R ″: lower hydrocarbon In the uranium adsorbent of the present invention, the calixarene derivative represented by the above formula (I) is water-soluble and captures uranyl ion (▲ UO ²⁺ ₂ ▼). It is important to have the correct cavity to inspire. Therefore, in the formula (I), n is in the range of 4 to 10, and when n is 3 or less, the synthesis is extremely difficult and the uranium adsorption property is poor, so that it cannot be used. Further, when n exceeds 10, it is difficult to synthesize, and the flexibility of the calyxalene derivative, which is a cyclic compound having a rigid unit of phenylmethyl group, increases in an aqueous solution.
It cannot be used because the adsorption selectivity for ▲ UO ²⁺ ₂ ▼ decreases.

Further, z in the above formula (I) is necessary for imparting water solubility to the calixarene derivative of the above formula (I) and imparting a functional group for reaction with the resin to be immobilized,
Examples include SO ₃ M, NO ₂ , NH ₂ , COOM ′, OM ″, and OR ′ described above.

M, M ′, M ″ may be hydrogen, ammonium ion, lower alkyl ammonium ion, metal ion or the like, but hydrogen or metal ion is preferable.

R ′ and R ″ are preferably those which do not reduce the water solubility and hydrophilicity of various functional groups as described above and the reactivity of copolymerization with a resin.

With respect to x and y, as long as the water solubility of the calixarene derivative and the performance as a uranium adsorbent are not deteriorated due to the hydrophilicity of OR and SO ₃ M and the number of n in the formula (I), There is no particular limitation.

The calix [n] arene derivative represented by the above formula (I) has a larger ring structure as n becomes larger, and rotation in —CH ₂ — becomes easier. Therefore, the calix [n]
Changes in the configuration of the allene derivative can also be observed, but when n is less than 6 and R = H, hydrogen bonds due to OH act strongly, and OR (or SO ₃ M) is oriented in a certain direction. High probability of ("cone" structure). When R is not hydrogen or n ≧ 6, it is necessary to consider the interaction between the solvent and the calix [n] arene derivative.
A structure in which the orientation of OR (or SO ₃ M) is alternated without taking a structure (“alterate” structure) is also possible. In the host-guest complex formation reaction of ▲ UO ²⁺ ₂ with a calix [n] arene derivative, when R is a carboxylic acid having a lower alkyl group, coordination of three carboxylates of calix [n] arene is sufficient. Thus, a good uranium adsorbent can be obtained regardless of the above-mentioned conformation, but in the case of other substituents, it is preferable that it has a cone structure.

The calixarene derivative represented by the general formula (I) can be prepared from calix [n] arene and sulfuric acid.

The calix [n] arene can be obtained, for example, from CD Gutsche
nts of Chemical Research, 1983 (16) 161-170) to debutylate p-tert-butylcalix [n] arene in toluene with a dealkylating agent such as anhydrous aluminum chloride. Can be made by

In a flask equipped with a reflux condenser, calix [n] arene 1-20 g, preferably 5-15 g, 90% or more, preferably 95%
% Or more, more preferably 98% or more concentrated sulfuric acid 10 to 150 ml, preferably 40 to 100 ml, heated (preferably 80 ° C. or more) and dissolved, and usually 1 hour or more, preferably 2 hours or more, more preferably Is reacted at 60 to 100 ° C, preferably 70 to 90 ° C for 3 to 5 hours. After completion of the reaction, the content is cooled, and the precipitated p-sulfonic acid calix [n] arene is separated and washed to obtain R = R in the formula (I).
A compound of H and M = H can be obtained. When R is a lower alkyl group, a solvent such as water, which dissolves the alkylating agent with p-sulfonic acid calix [n] arene and a suitable alkylating agent such as an alkyl halide,
It can be dissolved in methanol, ethanol, THF, etc. and the alkyl group can be substituted at the OH site. Alternatively, when R is a carboxylic acid having a lower alkyl group, a halogenated alkylcarboxylic acid can be used to substitute the lower alkyl carboxylic acid at the OH site of the above general formula. Compounds other than H for M can be obtained by ion exchange with various ions.

The calixarene derivative represented by the general formula (I) has a very good adsorption performance for uranyl ions in seawater, but for industrial use, the calixarene derivative is used in industrial water in order to maintain its uranium adsorption performance. It is necessary to save the formation and immobilize it on the resin.

The form of immobilization includes microencapsulation, embedding with a water-absorbing gel, immobilization by ionic bond or immobilization by covalent bond, and is not particularly limited, but efficiency as a uranium adsorbent, freedom of form, durability, etc. Therefore, resin fixing by covalent bond is preferable.

The calixarene derivative represented by the general formula (I) traps uranyl ions by the cavity formed by -OR attached to the benzene ring, and the number of -OR necessary for trapping uranyl ions is , 3 or more in the same direction. Therefore, without breaking the ring structure of the general formula (I),
It can be immobilized by introducing into the benzene ring a functional group that reacts and bonds with other resins.

De HC with, for example, the formula part of -SO ₃ M of (I) into a -NH ₂ group, a polystyrene resin having a chloromethyl group
l reaction by -NH-CH ₂ - can be immobilized to the resin by forming a bond. Alternatively, a part of the general formula (I), —SO ₃ M
Is converted to --SO ₂ Cl group, and dehydrochlorination with the resin having amino group is carried out.
It can be immobilized on the resin by forming a —SO ₂ NH— bond by the reaction.

As the resin to be immobilized, polyethylene, polypropylene, polystyrene, ABS resin, polyvinyl chloride, polyacrylonitrile, polyester, synthetic resins such as polyamide, and semi-synthetic cellulose acetate, cellulose nitrate, methyl cellulose, ethyl cellulose, regenerated cellulose, etc. Resins and natural polymers such as cellulose, starch and chitin can be used.

The form of the resin is fibrous, film-like, sheet-like,
Granular and other forms are possible, but for the purpose of uranium adsorbent resin, it has a large surface area, large flexibility, easy recovery, good adsorption and desorption operation, durability It can be determined as appropriate depending on factors such as good property.

(Effects of the Invention) The calixarene derivative (I) used in the uranium adsorbent of the present invention is highly water-soluble, and has a cavity design and a functional group of a cavity as a host that forms the coordination compound most with the target uranyl ion. It can be freely introduced, and its skeleton does not have flexibility such as other cyclic ligands such as crown ether, so it shows high selectivity for uranyl ion and adsorption of other metal ions. It has a characteristic that it is not very active. Therefore, the adsorption of uranium present in seawater is extremely selective and has a large adsorption power. Further, the uranium adsorbent of the present invention is neither highly toxic nor expensive like crown ether. Therefore, by using the uranium adsorbent of the present invention, it is possible to very efficiently adsorb uranium in seawater or wastewater,
In addition, since the adsorption of uranium is suppressed, the purity of adsorbed uranium is high, and the purification process can be greatly shortened.

Further, the uranium adsorbent according to the present invention in which the general formula (I) is immobilized has a form of fibrous, granular, membranous, film-like,
Since it can be formed into any shape such as sheet or honeycomb, it is possible to adsorb, desorb, and concentrate uranium in the most efficient manner according to the purpose. it makes sense.

(Examples) Hereinafter, the present invention will be described in more detail with reference to Examples.

In a flask equipped with a stirrer and a condenser tube, add 7.78 g of calix [6] arene to 50 ml of 98% concentrated sulfuric acid and stir 8
Stirring was continued for 3 hours at 0 ° C. The end point of the reaction is the time when the water-insoluble substance disappears.

Then, the mixture was cooled to room temperature, and the precipitated crystals were separated and washed with 98% concentrated sulfuric acid to obtain p-sulfonic acid calix [6] arene crystals. The crystals obtained are dissolved in water and neutralized with barium carbonate to separate out the formed barium sulfate precipitate. Sodium carbonate is added to the solution to prepare an aqueous solution of sodium p-sulfonate calix [6] arene. Of solution
Add sodium carbonate until pH 8-9.

The aqueous solution is treated with activated carbon and then dried under reduced pressure. The residue is dissolved in water and the insoluble matter is separated and separated. The liquid is treated with activated carbon again, the activated carbon is removed, and the residual liquid is concentrated. It was confirmed from the analysis results shown in Table 1 below that the reaction product obtained by adding ethanol to the concentrated solution, followed by fractionation and crystallization was p-sodium calix [6] arene p-sulfonate. (The following formula) The starting material, calix [6] arene, was prepared by the method of Gutsche et al. (CD Gutsche et al., J. Am. Chem. Soc., 103 3782 (19
82)) p-tert-butylcalix [6]
Allene was obtained by debutylation in toluene with a dealkylating agent such as AlCl ₃ .

Then, in a flask equipped with a stirrer and a cooling tube, 1 g of the above sodium p-sulfonate calix [6] arene and NaOH were added.
2 g, acetic acid monobromide (3.6 g) and water (10 ml) were added, and the mixture was heated and reacted at 80 ° C. for 24 hours.

After completion of the reaction, the reaction solution was cooled to room temperature, dried under reduced pressure, the residue was dissolved in 0.1N NaOH aqueous solution (10 ml) and heated at 80 ° C. for 4 hours. Then, after drying under reduced pressure, the residue was thoroughly washed with ethanol. The resulting solids are paper chromatograph, IR, NMR
It was confirmed by the above analysis that it was sodium O-carboxymethyl-p-sulfonate calix [6] arene (the following formula).

Example 1 Sodium O-carboxymethyl-p-sulfonate calix [6] (formula) prepared above was added with concentrated nitric acid in diluted sulfuric acid (water / concentrated sulfuric acid = 3/1) to prepare -SO ₃ Na
A portion of the nitration (-NO ₂ of). This partially nitrated product was dissolved in a water / methanol solution, and in the presence of activated carbon, ferric chloride salt and hydrazine, the nitro group was converted to an amino group at reflux to carry out partial amination.

The disappearance of absorption of the nitro group can be confirmed by IR.

Then, 10 g of finely crosslinked chloromethylated polystyrene (chloromethyl group, 4 meq / g) and 5.7 g of the partially aminated calix [6] arene derivative of the formula obtained above were added to DM.
After stirring at room temperature in the presence of K ₂ CO ₃ for about 1 week in F, the resin was separated, washed with water, methanol and THF, and dried to form a partially aminated calix [6] arene derivative of polystyrene resin. It could be fixed (0.5 mmol / g-resin).

Example 2 O-Carboxymethyl-p-sulfonic acid sodium calix [6] arene of the above formula was heated under reflux in thionyl chloride for 6 hours, poured into ice-bearing water, and then stirred at room temperature for one day. the -SO ₃ part of M in was chlorosulfonylation (-SO ₂ Cl).

Next, the crosslinked polystyrene resin containing an aminomethyl group (aminomethyl group content: 2.2 mmol / g-resin) and the partially chlorosulfonylated calix [6] arene derivative of the above formula were added to a solution of K ₂ CO _{3 in} a DMF solution. The reaction was continued at 70 ° C. for about one week below.

After separating the resin, wash with water, methanol, chloroform,
The calix [6] arene derivative of the above formula was immobilized on a polystyrene resin by drying. Based on the sulfur content in the resin, the amount of calix [6] arene derivative is 0.82 mmol
/ g-resin.

Example 3 0.2-0.3 g of the polystyrene resin having the calix [6] arene derivative immobilized thereon obtained in Examples 1 and 2 was added to 1N-NaOH100.
It was wetted to ml and stirred for 24 hours, and then thoroughly washed with water.

0.1 g of this alkali-treated resin was packed in a column, and seawater was passed at 30 ml / min. The column was kept warm at 25 ° C ± 2 ° C.

After the adsorption was continued for 7 days and 14 days, the adsorbed uranium was eluted by washing the column with 1N-HCl. Uranium was quantitatively analyzed by a conventional colorimetric method.

The results are shown in Table 1, and it is understood that the performance is far better than that of the conventional uranium adsorbing resin.

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI Technical display location C02F 1/28 B C07C 309/42 7419-4H C08G 61/02 NLF 8215-4J 81/00 NUS 8416-4J 85 / 00 NVA 8416-4J C09K 3/00 108 9155-4H

Claims (2)

[Claims] 1. A uranium adsorbent comprising a resin on which a calixarene derivative represented by the following general formula (I) is immobilized. However, n: 4 to 10 R: hydrogen, lower alkyl group, lower alkyl carboxylic acid or salt thereof, unsaturated alkyl group or aromatic hydrocarbon x, y: hydrogen, alkyl group, aromatic hydrocarbon z: SO ₃ M, NO ₂ , NH ₂ , COOM ′, OM ″, OR ′, M, M ′, M ″: hydrogen, ammonium ion, lower alkylammonium ion, metal ion R ′: hydrogen, R ″ OH, R ″ COOH, R ″ NO ₂ , R ″ NH ₂ ,
R ″ SO ₃ M R ″: Lower hydrocarbon 2. The uranium adsorbent according to claim 1, wherein the calixarene derivative is immobilized on the resin by a covalent bond.