JPS632896B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for extracting uranium from dilute solutions, particularly seawater. More specifically, the present invention relates to a method for collecting uranium using a chelate resin having an amidoxime group as a functional group, which selectively captures uranium and has an improved adsorption reaction rate. Polymers with amidoxime groups as functional groups are, for example, PREPARATIVE METHODS OF
POLYMER CHEMISTRY, WR Sorenson,
Co-authored by TWCampbell INTERSCIENCE Publishing NEW
As described on page 171 of YORK, it is known that it is obtained by reacting polyacronitrile with hydroxylamine and selectively captures various heavy metal ions. Also, Patent Publication 1973-
As described in No. 32834, chelate resins containing amidoxime groups are known to have the ability to selectively capture uranium in particular, and are used for waste liquid treatment during the production of uranium nuclear fuel for nuclear reactors or for uranium in seawater. It is widely used for collection, etc. Furthermore, as described in Japanese Patent Publication No. 56-126445, it is known that a resin containing an amidoxime group exhibits a higher uranium adsorption rate when immersed in an alkaline aqueous solution to swell it. However, in the above-mentioned amidoxime group-containing chelate resin, the reaction rate of chelate formation between the functional group fixed in the resin and uranium is slow, or the diffusion of uranium in the resin particles is slow, so that low concentration uranium-containing solutions cannot be used. The utilization of exchange groups in the resin is generally low during short-term contact in the resin. As a result of our earnest efforts to increase the utilization rate of exchange groups in chelate resin and improve the reaction rate of uranium capture, the present inventors have successfully incorporated fine-grained chelate resin into a hydrophilic and water-insoluble organic polymer gel. The present invention was completed by discovering that the reaction rate of uranium capture can be improved by dispersion and inclusion. The present invention aims to provide a method for extracting uranium from dilute uranium-containing solutions, especially seawater, by means of chelating resins containing amidoxime groups with improved adsorption rates; This can be easily achieved by bringing a uranium-containing solution into contact with a chelate resin in which a fine-grained polymer containing the group is dispersed in a hydrophilic and water-insoluble organic polymer gel. To explain the present invention in detail below, the chelate resin used as an adsorbent in the method of the present invention is produced by dispersing and incorporating a fine particulate polymer containing an amidoxime group into a hydrophilic and water-insoluble organic polymer gel. It was manufactured by The amidoxime group-containing polymer used in the present invention is produced by reacting a nitrile group-containing polymer with hydroxylamine.
Examples of the polymer having a nitrile group include a homopolymer of a monomer having a nitrile group, a copolymer of monomers having a nitrile group, or another monomer copolymerizable with a monomer having a nitrile group. A copolymer with a polymer is used. Examples of monomers having a nitrile group include not only acrylonitrile but also α-substituted acrylonitriles such as methacrylonitrile, chloracrylonitrile, and vinylidene cyanide, as well as crotonitrile, 2
-cyanoethyl acrylate, 2-cyanoethyl methacrylate, etc., and these may be used alone or in combination of two or more. Usually acrylonitrile or methacrylonitrile is used. As other monomers that can be copolymerized, all aliphatic and aromatic compounds that can be copolymerized with the monomer having a nitrile group can be used, such as ethylene, propylene, butylene, acrylic acid,
Methacrylic acid and its esters, vinyl halides, vinyl esters, vinyl alcohol, vinyl ethers, aliphatic monovinyl compounds such as vinylidene halides, aromatic monovinyl compounds such as styrene and vinyltoluene, divinylbenzene,
Polyvinyl compounds such as diallyl phthalate, ethylene glycol diacrylic acid or dimethacrylate, or glycerin dimethacrylate are used. In addition to the above-mentioned polymers having nitrile groups, for example, cyanoethylated cellulose, cyanoethylated polyvinyl alcohol, cyanoethylated glycerin methacrylate, etc.; halomethylated copolymers of aromatic monovinyl compounds and polyvinyl compounds or haloacetalized polyvinyl alcohols. , for example, treated with iminodiacetonitrile or iminodipropionitrile to introduce a nitrile group; Furthermore, an aromatic or aliphatic compound having a nitrile group, such as dicyandiamide, oxybenzonitrile, dioxybenzonitrile, etc., as one component. A condensate of is also used. The reaction between a polymer having a nitrile group and hydroxylamine is carried out according to a conventional method, but preferably, a methanol or ethanol solution of hydroxylamine, or a methanol or ethanol solution of hydroxylamine sulfate or hydrochloride is reacted with water. It is carried out by adding an alkali such as sodium oxide or potassium hydroxide to neutralize all or part of the salt and reacting it at 40 to 100°C.
This reaction mainly converts nitrile groups into amidoxime groups. The particulate polymer containing an amidoxime group used in the present invention has a particle size of 50 μm or less, preferably 10 μm or less. Hydrophilic and water-insoluble organic polymer gels include linear polymers with anionic functional groups, such as polystyrene sulfonic acid and polyacrylic acid, and linear polymers with cationic functional groups, such as polyvinylbenzyltrimethylammonium hydroxide. , a polyion complex consisting of a combination with polyethyleneimine, polyethylene piperazine, etc., a hydrophilic monomer such as poly-2-hydroxyethyl methacrylate, polyethylene glycol mono(meth)acrylate, polyglycerin mono(meth)acrylate, etc., and two molecules in the molecule. Divinylbenzene, polyethylene glycol di(meth) having an unsaturated carbon-carbon bond of
Starch Gels made by crosslinking various starch derivatives, polysaccharides such as cellulose and cellulose derivatives, oligosaccharides such as pullulan, polyvinyl alcohol, etc. with dialdehydes such as gluoxal, malonaldehyde, succinaldehyde, and phthalaldehyde and making them insoluble in water; A gel obtained by crosslinking polyacrylic acid or polyacrylamide with hydrazine is used. The amount ratio of the particulate polymer containing an amidoxime group to the hydrophilic and water-insoluble organic polymer gel used in the chelate resin of the present invention varies depending on the type and properties of the hydrophilic and water-insoluble organic polymer gel. Although it is not possible to set the image constant and it must be optimized, it is usually 1:10 to 10:1 on a weight basis.
Preferably, the ratio is from 1:5 to 3:1. Various methods are used to disperse and incorporate the polymer containing an amidoxime group into a hydrophilic and water-insoluble organic polymer gel, depending on the type and properties of the hydrophilic and water-insoluble organic polymer gel. , normal particle size (several hundred microns) containing amidoxime groups
After the polymer m) is pulverized and atomized, it can be dispersed and included in a hydrophilic and water-insoluble organic polymer gel. On the other hand, the above-mentioned nitrile group-containing resin matrix of normal particle size is pulverized to obtain a fine-grained matrix polymer, or a monomer having a nitrile group is processed into a fine-grained polymer by known emulsion polymerization or other polymerization method. A method is also used in which these polymers are dispersed in a hydrophilic and water-insoluble organic polymer gel, and then the nitrile groups are converted into amidoximes. Alternatively, a method may be used in which a fine particulate polymer containing a nitrile group produced by known emulsion polymerization or other polymerization methods is converted into an amidoxime, and then dispersed and incorporated into a hydrophilic and water-insoluble organic polymer gel. For example, when using an ionic complex consisting of a linear polymer having an anionic functional group and a linear polymer having a cationic functional group as a hydrophilic and water-insoluble organic polymer gel, first both linear polymers are After producing a partially bonded ionic complex and adding and mixing thereto a fine particulate polymer containing an amidoxime group or a fine particulate matrix polymer containing the above-mentioned nitrile group (hereinafter collectively referred to as particulate polymer). A method can be used that promotes the formation of ion complexes, forms a water-insoluble gel, and if necessary further amidoximizes. In addition, when using a crosslinked product of a hydrophilic linear polymer such as polysaccharide or polyvinyl alcohol as a hydrophilic and water-insoluble organic polymer gel, the hydrophilic linear polymer is partially crosslinked in advance,
Next, a method in which a fine particulate polymer is added and mixed and then the crosslinking reaction is promoted to produce a water-insoluble gel, or a crosslinking reaction is performed in one step in the presence of a hydrophilic linear polymer and a particulate polymer to form a water-insoluble gel. In either method, after producing an insoluble gel, if necessary, it is subjected to an amidoximation reaction. In addition, when using a polymer of hydrophilic monomers such as polyacrylamide or polyethylene glycol dimethacrylate gel as a hydrophilic and water-insoluble organic polymer gel, fine particulate polymers are dispersed in a monomer containing a crosslinking agent monomer in advance. After this, various polymerization methods are used to produce a water-insoluble gel, and the resulting gel is subsequently subjected to an amidoximation reaction, if necessary. The chelate resin of the present invention, in which the particulate polymer having an amidoxime group is dispersed and included in a hydrophilic and water-insoluble organic polymer gel, has a high adsorption reaction rate for uranium, so it can adsorb uranium from a dilute solution containing uranium. Extremely useful for separation. The uranium adsorption and elution operations in the present invention are carried out by conventional methods. Usually, a solution containing uranium is passed through a resin tower filled with the above resin to adsorb uranium onto the resin, and then a desorbing agent such as hydrochloric acid is passed through to elute the uranium, and then the uranium is adsorbed again. A continuous flow system is used. The resin used in the method of the present invention adsorbs uranium in a wide range from weak acidity to alkalinity, but it is preferably used in neutral to weak alkalinity. When collecting uranium from seawater, it is sufficient to pass the seawater as it is or after removing suspended matter to a resin tower. The chelate resin used in the present invention exhibits a higher uranium adsorption rate compared to conventional resins even as it is, but if it is immersed in an alkaline aqueous solution to swell and then used for uranium adsorption, it exhibits an even higher uranium adsorption rate. show. The above alkali treatment methods include sodium hydroxide, potassium hydroxide, calcium hydroxide, etc.
A method is used in which an aqueous solution of 0.1 normal to 5 normal is brought into contact with the resin at room temperature. 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 (Production of resin) A commercially available amidoxime group-containing chelate resin Diamond CR50 (manufactured by Mitsubishi Chemical Industries, Ltd.; registered trademark, normal particle size product) was ground using a sand grinder.
A slurry of uniform fine particles of 2 μm was obtained. An appropriate amount of water was added to this to obtain a resin suspension with a solid content of 10%. Next, 100ml of a 0.2eq/polyvinylbenzyltrimethylammonium hydroxide aqueous solution with a molecular weight of 20,000 and 100ml of a 0.2eq/polystyrene sulfonic acid aqueous solution were mixed, and further diluted with 400ml of methyl alcohol to form a slurry-like polyion complex. A white precipitate was formed. To this slurry, 100 ml of the suspension of the above-mentioned amidoxime group-containing fine particulate resin was added and stirred until the slurry became uniform. The resulting slurry liquid was allowed to stand under heating and reduced pressure to evaporate the liquid components to obtain 24.7 g of a lumpy chelate resin. The above chelate resin was crushed and classified into 20 to 50 meshes to obtain 16.0 g of chelate resin. Example 2 (Production of resin) 20 g of polyvinyl alcohol (manufactured by Nippon Gosei Co., Ltd., Gohsenol NL-05, degree of saponification 98.5%) was
It was added to 180 g of an emulsion containing polyacrylonitrile of 1 μm or less and dissolved at 95° C. for 1 hour. After cooling, 8 ml of 25% glutaraldehyde and 20 ml of 1 normal hydrochloric acid were added to the slurry, and a crosslinking reaction was carried out at 60° C. for 2 hours to obtain a water-insoluble gel. After crushing and classifying this gel, it was added to 300 ml of a 3% hydroxylamine methanol solution, and
By carrying out the amidoximation reaction at ℃ for 4 hours, 200 ml of chelate resin was obtained in a swollen state. Example 3 (Production of resin) 4 g of polyacrylamide with a molecular weight of 3 x 10 ⁵ was
It was dissolved in 200 ml of water to obtain a 2% aqueous solution. Add 0.6g of hydrazine hydrate to this aqueous solution,
A white opaque slurry liquid was obtained by carrying out a crosslinking reaction at 60°C for 10 hours. To this slurry liquid, 40 ml of the suspension of the amidoxime group-containing fine particulate resin used in Example 1 was added and mixed until a uniform slurry was formed. The resulting slurry was air-dried at 50° C. for 3 days to obtain 6.3 g of a water-insoluble lumpy resin. After crushing the above lump resin, it is classified into 20 to 50 meshes.
5.3g of chelate resin was obtained. Example 4 The chelate resins obtained in Examples 1, 2, and 3 and Diaion CR50 (20 to 50 meshes) were immersed in 100 ml of 1 normal sodium hydroxide solution at room temperature for 24 hours in a wet state to a volume of 5 ml. Then, it was treated with alkal and then washed with water. The above resin was placed in a column with an internal volume of 200 ml, and upward flow of seawater was passed through it at a space velocity of 1200 hr ^-1 at 25°C. After 10 days, the uranyl ions adsorbed on the resin were eluted with acid, and the arsenazo spectrophotometry was performed. The amount of uranium adsorbed per unit weight of chelate resin was determined using the following method. The results are shown in the first part. 【table】

Claims (1)

[Claims] 1. A chelate resin in which a particulate polymer containing an amidoxime group is dispersed and included in a hydrophilic and water-insoluble organic polymer gel is brought into contact with a uranium-containing solution to adsorb uranium onto the resin. A method for collecting uranium from a uranium-containing solution, characterized by: 2. The method for collecting uranium according to claim 1, wherein the particulate polymer containing an amidoxime group is a particulate polymer having a particle size of 50 μm or less. 3 The ratio of the fine particulate polymer to the hydrophilic and water-insoluble organic polymer gel is from 1:10 by weight.
The method for extracting uranium according to claim 1 or 2, characterized in that the ratio is within the range of 10:1. 4. Claims 1 to 3, characterized in that the organic polymer gel is a polyion complex consisting of a linear polymer having an anionic functional group and a linear polymer having a cationic functional group. A method for extracting uranium as described in any of the paragraphs. 5. The method for collecting uranium according to any one of claims 1 to 3, wherein the organic polymer gel is a dialdehyde crosslinked product of polyvinyl alcohol. 6. The method for collecting uranium according to any one of claims 1 to 6, characterized in that the chelate resin is treated with an aqueous alkaline solution to swell it and then brought into contact with a uranium-containing solution.