JPH02290249A - Uranium adsorption material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a uranium adsorbent whose composition is a copolymer of a vinyl monomer and a radically polymerizable vinyl monomer containing an amine group. <Prior art> Uranium adsorbents using functional resins such as ion exchange resins or chelate resins have been put to practical use in the purification process from uranium ore leachate since ancient times. Although it has not yet been put to practical use, this method is the subject of industrial-scale development research around the world as a promising method for recovering uranium from seawater as a future uranium resource. Although it has not yet been industrialized in nuclear fuel reprocessing plants, adsorbent-based methods have been attracting attention from early on as a method to replace the current wet method, which is associated with large amounts of solvent deterioration, such as the Burex method. I was receiving it. All of the above-mentioned processes correspond to the main steps of the process, but in general, uranium is a hazardous substance to the biological environment, both as a heavy metal and as a radioactive substance, so it is used in various places in the nuclear industry in the form of wastewater treatment, etc. Therefore, it is necessary to separate uranium from a dilute mixed solution. Ion exchange resins used in the purification process from uranium ore leachate contain strong sulfur V! Acidic uranium solution? In order to absorb mainly the anionic complex salt UO (SO.),
Strongly basic ion exchange resins with tertiary amine groups as active groups are used. Commercially available e.g. Amberlite IRA
-400 and its series, Dowex I and its series grades belong to this system. On the other hand, the use of weakly basic ion exchange Pi4 has also been proposed. For example, ion exchange resins of pyridine-divinylbenzene copolymer are said to give excellent results in uranium recovery from low-grade uranium ores. (Yasuda et al., Special Publication No. 54-37016
Publication number: JP 61-1171: JP 54-1
Publication No. 0:1715. Koei Chemical Industry ■, technical data, weak basic ion exchange resin KEX). Hydrous titanium oxide adsorbents and amidoxime adsorbents are considered to be promising adsorbents for recovering uranium from seawater (Egawa et al., Journal of the Atomic Energy Society of Japan 29 f121).
1079 f19871). There are many other adsorbent proposals. Among commercially available chelate-type adsorption resins, Sumikylate CR2, for example, exhibits excellent uranium adsorption ability. These existing technologies are characterized by adsorption capacity, retraction to other ions, adsorption rate, swelling resistance, desorption properties, and oxidation resistance. Although it has met the demands of industry to some extent in terms of chemical resistance and deterioration resistance, in order to satisfy the various uses mentioned above, it is necessary to complement the performance of conventional functional materials. There is a need to provide many unique functional materials at lower prices. Problems to be Solved by the Present Invention> The purpose of the present invention is to. Our objective is to provide a uranium adsorbent that has a unique balance between acid absorption capacity and uranium adsorption capacity and can be manufactured at low cost, thereby providing the basis for establishing a more complete uranium recovery technology. <Means for solving the problem> As a result of the inventors' intensive research from this perspective,
We have discovered that a copolymer of a vinyl monomer with a specific composition that has never been seen before and a radically polymerizable vinyl monomer containing an amino group has the characteristics and possibilities described above and is optimal for the purposes of the present invention. In other words, the present invention is! 11 20 to 98% vinyl monomer, general formula + A3 (where RI is hydrogen or methyl group. A uranium adsorbent comprising a copolymer containing one or more amino group-containing radically polymerizable amino groups represented by the following formula and 2 to 80% by weight of a nil monomer. (2) Uranium adsorption according to claim 2, wherein the amino group-containing radically polymerizable vinyl monomer is selected from the group consisting of dimethylaminoprobyl acrylamide, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate. {3} The vinyl monomer is 11m or 2 selected from the group consisting of styrene, vinyl chloride, butadiene, methyl acrylate, ethyl acrylate, butyl acrylate and methyl methacrylate. The purpose of the present invention is to provide the uranium adsorbent described above, and to provide the materials necessary for completing the uranium separation and recovery technology.An anionic solution polymerization method is also available for producing the copolymer used in the present invention, but an emulsion polymerization method is also available. is most commonly applied.The polymerization conditions are within those of ordinary emulsion polymerization polymer production processes.Therefore, it can be said that this copolymer has an excellent economic basis.

Preferred specific examples of the amino group-containing radically polymerizable vinyl monomer represented by the general formula (Al) for the styrene copolymer produced in the present invention include dimethylaminoethyl acrylamide, dimethylaminopropylacrylamide, dimethylaminobutylacrylamide, diethylamino Ethylacrylamide, diethylaminobrobylacrylamide, diethylaminobutylacrylamide, di-n-butylaminoethyl acrylamide, di-
n-butylaminobutylacrylamide, di-n-butylaminobutylacrylamide, N-fl. l-
dimethyl-3-dimethylaminobrobyl)acrylamide, N-(2-methyl-3-dimethylaminobutylic)acrylamide, and their corresponding methacrylamide derivatives, dimethylaminoethyl acrylate, dimethylaminobutyl acrylate , dimethylaminobutyl acrylate, diethylaminoethyl acrylate, diethylaminobrobyl acrylate, diethylamine butyl acrylate. N-(2-methyl -3-dimethylaminobrobyl) acrylate, and their corresponding methacrylamide derivatives. Particularly preferred comonomers include dimethylaminopropylacrylamide, dimethylaminobrobyl methacrylamide, dimethylaminopropylacrylamide, di-n-propylaminobutylacrylamide, di-n-butylaminobutylacrylamide, dimethylaminoethyl methacrylate, and diethylaminobutylacrylamide. An example is ethyl mequaacrylate. The vinyl monomer copolymerized with the fA) comonomer used in the present invention is not particularly limited, but a suitable monomer may be selected based on copolymerizability, etc. For example, styrene, vinyltoluene, butadiene, isobrene,
Vinyl halides such as vinyl chloride, vinyl bromide, vinylidene chloride, vinyl esters such as vinyl acetate, vinyl blobionate, vinyl oxate, vinyl bivalate, vinyl laurate, vinyl versatate = methyl (meth)acrylate, ( (Meth)acrylic acid and carbon atoms 1-18 such as ethyl meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate
Ester compound with alkyl alcohol: (meth)
Examples include acrylonitrile, and 111 or a mixture of two or more of these may also be used. It is also possible to copolymerize functional vinyl monomers containing amino groups, hydroxyl groups, carboxylic acid groups, methoxy groups, etc., if necessary. In the general formula (A) representing an amino group-containing radically polymerizable vinyl monomer, comonomers corresponding to comonomers where n is greater than 1 or 6 and/or R and R whose number of carbon atoms is greater than 5 are based on the industrial standards of the comonomers themselves. Not only are they relatively difficult and expensive to synthesize, but some are unstable under heating or have too high a viscosity, making it difficult to apply them to polymerization processes. Polymerization methods include solution polymerization, bulk polymerization, suspension polymerization, etc. Although any commonly used polymerization method can be used, the most preferred method is synthesis by emulsion polymerization. As the polymerization initiator used in emulsion polymerization, any compound that generates free radicals can be used, such as 2.2°-azobis(2-aminobutylene) hydrochloride, peroxide Alternatively, a combination of this with a reducing agent, penzoyl peroxide, cumenehyde peroxide, t-butylhyde peroxide, or a combination of these with a reducing agent is preferably used. Anionic polymerization initiators such as ammonium persulfate can also be used. Generally used cationic or nonionic surfactants are used as the surfactant when carrying out water-based polymerization. A dispersion is obtained. The content of the amino group-containing radically polymerizable vinyl 1,000 polymer in the new copolymer of the present invention is 2 to 80ffiffl.
%. If the amino group-containing radically polymerizable vinyl monomer is less than 2% by weight, the uranium adsorption capacity will be too low, and if the content is high, exceeding 80% by weight, the acid absorption capacity will be strong and the resin will swell in the acidic solution and may change shape. The resin cannot be used as is because it is destructive. The acid absorption ability of the resin is probably due to the basicity of the amino group, but the swelling of P4 fat is thought to be strongly related to this absorption ability and intermolecular cohesive force. Therefore, crosslinking is an essential condition in order to suppress resin swelling to an industrially optimum level. On the other hand, the ion exchange rate of the resin decreases as the degree of crosslinking increases. The number of functional groups available for exchange also decreases. In addition, shape workability deteriorates. A comonomer content of about 80% by weight is the upper limit for this copolymer to be industrially useful.
In producing the copolymer of the present invention, vinyl monomers are used to facilitate stable supply of the amino group-containing radically polymerizable vinyl monomer to the polymerization system by pump, and to increase the flexibility of the copolymer. At least one other copolymerizable ethylenically unsaturated comonomer may be combined as necessary. The polymerized units of the ethylenically unsaturated comonomer used in this case are:
It is 0 to 20% by weight, preferably 0 to 15% by weight. Preferred specific examples of the ethylenically unsaturated comonomer include methyl acrylate, ethyl acrylate, methyl methacrylate, vinyl acetate, dimethylaminoethyl methacrylate, and dimethylaminoethyl acrylate. Although it is possible to use this copolymer in its polymerized form, it is also possible to purify the copolymer by an appropriate method, such as precipitation using methanol, and then mold it into a shape suitable for adsorption/desorption using thermoplasticity. It is also an advantageous method to do so. This copolymer, which is not strongly crosslinked, can be freely molded into tubes, mats, films, rods, fibers, nonwoven fabrics, woven fabrics, hollow fibers, etc., and can be used not only alone but also with other polymers and metal materials. It can also be applied as a composite material with inorganic materials such as rice, glass, and wood. When used as a composite material, it is common for this copolymer to share the functionality and other materials to share the role as a structural material. When this copolymer is composed of a less polar vinyl monomer and a more polar amino group-containing radically polymerizable vinyl monomer, the range of materials that can be selected as other materials is wide due to their affinity. This further increases the usefulness of this copolymer. The uranium adsorption ability of this copolymer is thought to depend on the chelating ability of the comonomer and the ion exchange ability based on the weak basicity of the amino group. This amino group is easily converted into a quaternary ammonium salt, and for example, in an acidic solution of hydrochloric acid, -Nl! “!C.I.
It would be 13+2CI-. The reason why the adsorption performance of this copolymer is phenomenologically strongly controlled by pH, similar to that of an inorganic resin or a chelate resin, is that the main cause of uranium adsorption in this copolymer is the nitrogen atoms of the amino groups. This suggests that. The process of adsorption and separation of uranium from an aqueous solution using this copolymer generally takes the following form, but of course the scope of the patent claims is not restricted thereby. First, the aqueous solution to be treated is adjusted so that the pl1 after treatment is 4.5 to 9.8, more preferably 6.0 to 9.2.
At this time, it is important to frost the uranyl ions with anions such as carbonate ions and to prevent precipitation at the pH within the range of use. For adsorption, the aqueous solution to be treated is continuously passed through the filtration 23, which has a structure in which a fixed bed filled with beads or pellets of this resin to the required height or a filter equipped with a filter cloth made of fiber mat non-woven fabric or woven fabric is stacked as many times as necessary. Let. At this time, by selecting the size and shape of the packing or the mesh structure of the filter cloth, it is possible to create a wide variety of designs, focusing on, for example, pressure drop, effective adsorption capacity, adsorption speed, and the method of replacing the packing. Among these possibilities are
Of course, continuous systems using moving bed or fluidized bed systems are also included. When the amount of adsorption of this copolymer reaches the breakthrough point, immediately perform regeneration or replacement operations. For regeneration, a method using a uranium eluent after cleaning with a mineral acid has been proposed for weakly basic ion exchange resins (Japanese Patent Application Laid-Open No. 1986-1999).
103715). This copolymer can be sufficiently eluted simply by treatment with mineral acid. this?
The ease of 'a iii' is also an advantage of the present invention. Uranium itself is extremely dilute, and wet elution recovery of uranium may not be very economical when used as a safety measure for environmental conservation, where the simultaneous adsorption of other ions must be considered to some extent. In such cases, this copolymer can be discarded. It is preferable to incinerate this used adsorption resin in order to reduce its volume and recover uranium. Since this copolymer does not contain sulfur, it does not generate sulfur trioxide by itself when incinerated. Therefore, if the treated wastewater does not contain sulfuric acid radicals or other sulfur compounds, corrosion problems, which are the most important accident in incinerators, can be avoided. Even if wastewater contains sulfur compounds, it is relatively easy to replace them, so the above advantages can be taken advantage of by adding some process. This is another excellent aspect of the process using this copolymer. Examples> The present invention will be explained below using Examples and Reference Examples, but the present invention is not limited by these. Example 1 600 g of water is added to a 2 liter separable flask equipped with a reflux condenser, thermometer and stirrer. Dimethylaminopropylacrylamide (DMAPAA 380g 36% salt r:!I
52 g of i (hydrochloric acid corresponding to a molar ratio of [0] to the amino group of the copolymer) and 320 g of styrene were charged with stirring,
After raising the temperature to 60°C, the inside of the reaction system was purged with nitrogen gas. Next, a 5% aqueous solution of 2.2-azobis(2-amidinopropane) hydrochloride was fed into the reaction system at a constant rate for 4 hours to cause a reaction. After 4 hours, the temperature was further raised to 80°C, and the reaction was continued for 2 hours, and the polymerization was terminated when the residual heptanomer decreased to 0.5% or less. The emulsion thus produced was poured into acetone, precipitated, and separated and purified. Let this sample be A. Similarly. Sample B was obtained by polymerizing DMAPAA by replacing 80 g of diethylaminobrobyl acrylamide [DEAPAA1], and 240 g of styrene. 80g of n-butyl acrylate was charged and polymerized.
DMAPAA is dimethylaminoethyl methacrylate [
DMAEM) 80g, DMAPAA was replaced with diethylaminoethyl methacrylate (DEAEMI 80g) and polymerized to form Sample D and Sample E, respectively.The results of their characteristic analysis are as shown in Table 1.Table 1 Sample name ABC Styrene wt% DMAI'AA ' ” wt% DEAPAA” wt% nBA” vt% Total wt% 92.7 7.3 100.0 96.7 3.3 ・100.0 61.5 ■8.5 20.0 l00 .B Sample name D E Styrene wt% DMAEM” wt% DEAEIJ” wt% Total wt% 85.4 85.3 l4,6 14.7 100.0 100.0 Measured using a spectrometer IIcP-AES) SPS7000.The results are shown in Table 2, indicating that adsorption and desorption of uranium can be easily achieved by adjusting pl1.Table 2 ■ Dimethylaminopropylacrylamide 21 Diethylaminobrovir Acrylamide 3i n-butyl acrylate 41 Dimethylaminoethyl meccrylate 5+ Diethylaminoethyl methacrylate Example 2 In order to determine the pl1 characteristics of U adsorption of styrene copolymer, 1 g of powdered A was mixed with nitric acid in nitric acid prepared by pi{ Uranyl solution (contains 4 times the mole of carbonate ions, ) 5
0 cc and stirred with a stirrer at room temperature for 48 hours, after equilibration the pll and uranium concentration were measured. The initial uranium concentration is loOppIm in terms of uranium weight concentration. Experiment number pl1 U adsorption rate % l 2.0 3,4 6.4 7.0 7.6 Almost similar results were obtained with C. Example 3 Copolymer pellets A from Example 1 were immersed in various dilute nitric acids for 12 hours while stirring with a stirrer. A uranyl nitrate solution (uranium = f5[10
wtppm. Contains 4 times the mole of soda carbonate. Before adjustment pfl = 10.51 0.1 to 2.0 g of the present copolymer pellets subjected to the hydrogen ion adsorption treatment were added to 50 ml and stirred with a stirrer for about 16 hours. The final plI was 6.5-8.0. The adsorption results are shown in Table 3. Table 3 Experiment number U final concentration ppm IJ adsorption rate 1 (m
(ol-U/mol one exchange group) No precipitate was formed in any of the experiments. Copolymer B
．． Almost similar results were obtained with C. Example 4 Sample A of Example 1. B. The adsorption capacity of C was investigated in nitric acid aqueous solution. Add 2g of sample to nitric acid solution of various concentrations
0 ml for 16 hours and stirred. The results are shown in Table 4. D. Regarding H, the sample was 0.5g. Other conditions are the same. The results are shown in Table 4. 270. 700. 960. l200.

1:100. 0.26 0.32 b. 36 0.40 1 U adsorption amount per N conversion exchange group Table 4 Experiment number + 1″ final concentration pl1 L adsorption rate A-1 A-2 A-3 6.6 6.0 4,5 0.041 0 .096 0.I2 A-4 8-I B-2 B-3 C-I C-2 C-3 C-4 0-I O-2 E-I E-2 E-3 E-4 2.7 7.3 4.7 3.0 6.6 5.2 2,9 2.1 5.3 2,6 2.1 !,7 6,0 3.3 2,3 1.9 0.13 0, 12 0.l8 0.23 0.04ro 0.07 0.11 0.12 0.15 0.29 0.27 0.29 0.l6 0.58 0.65 0.81 11 per N conversion exchange group゜Adsorption amount (mol-If''/mol-exchange group) The alphabet in the experiment number represents the type of sample. Example 5 To determine the pH characteristics of styrene copolymer U absorption, powdered Ig was added to 50 ml of uranyl sulfate city liquid adjusted to p+{ with sulfuric acid, stirred with a stirrer at room temperature for 48 hours, and the pH after equilibrium and We measured the uranium concentration. The results are shown in Table 5. Table 5 Experiment number pll U adsorption rate % IN-11. S.O. 0. IN-H. SO4 l. 5 2.2 3.4 5.8 Almost similar results were obtained with copolymer E. Example 6 Styrene copolymer E powder was immersed in dilute sulfuric acid while stirring in a stirrer for 12 hours. pH of dilute sulfuric acid after immersion
The hydrogen ion concentration was adjusted so that it was almost the same as pl. Uranyl sulfate solution (500ppm uranium before adjustment pl
1.3.0) Pour 0.1 to 2.0 g of the powder of this copolymer E that has been subjected to the above-mentioned water absorption treatment into 50 ml, and add about 0.1 to 2.0 g of this copolymer E powder. Stir with a stirrer for 6 hours. Final pl+ is 2.5-3.0
Met. The adsorption results are shown in Table 6. Table 6 464, 0.045 486, 0.035 U adsorption amount per N-equivalent exchange group (la+oL-U/mol-exchange group) No precipitation occurred in any of the experiments. Effects of the Invention By using the copolymer of the vinyl monomer of the present invention and a radically polymerizable vinyl monomer containing an amino group, it has become possible to easily adsorb and desorb uranium in an aqueous solution. Experiment number U final concentration ppm U adsorption rate 1》3
14. 430. 457. 0.023 0.028 0. B35 0.035

Claims (3)

[Claims] (1) 20 to 98% by weight of vinyl monomer, general formula (A
)▲There are mathematical formulas, chemical formulas, tables, etc.▼(A) (In the formula, R_1 is hydrogen or a methyl group, X is O or NH, R_2 and R_3 are an alkyl group having 1 to 4 carbon atoms, and n is a 2 to 5 carbon number A uranium adsorbent whose composition is a copolymer containing 2 to 80% by weight of one or more amino group-containing radically polymerizable vinyl monomers represented by (integer). (2) The amino group-containing radically polymerizable vinyl monomer is one or two selected from the group consisting of dimethylaminopropylacrylamide, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate.
The uranium adsorbent according to claim 1, which is a uranium adsorbent of at least 1 species. (3) Uranium adsorption according to claim 1, wherein the vinyl monomer is one or two selected from the group consisting of styrene, vinyl chloride, butadiene, methyl acrylate, ethyl acrylate, butyl acrylate, and methyl methacrylate. body.