JPS6121699B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to the extraction of uranium from dilute solutions, particularly seawater. It is known that uranium can be extracted from seawater using an adsorbent, and inorganic adsorbents such as titanium hydroxide are mainly used. Also,
Among organic adsorbents, resins having amidoxime groups are known to have a selective adsorption ability for uranium (see Japanese Patent Application Laid-open No. 126088/1983). The present inventors investigated the adsorption of uranium using a resin having this amidoxime group, and found that
The present invention was completed based on the discovery that the rate of uranium adsorption is significantly faster when poly(meth)acrylate of polyalkylene polyol is used as a crosslinking agent. That is, according to the present invention, the alkylene group has 2 to 4 carbon atoms, and the alkylene group has 2 to 14 carbon atoms.
The skeleton is a crosslinked copolymer of at least one kind of multitubular compound selected from the group consisting of polyacrylate and polymethacrylate of polyalkylene polyols, and a monotubular compound, and the monotubular compound of this skeleton is Uranium can be easily recovered from a dilute solution, especially from seawater, by bringing a uranium-containing solution into contact with a resin having a structure in which an amidoxime group is bonded to the compound moiety and adsorbing uranium onto the resin. To explain the present invention in detail, the resin having an amidoxime group used as an adsorbent in the method of the present invention has an alkylene group having 2 to 4 carbon atoms and 2 to 14 carbon atoms as a crosslinking agent. It can be produced according to a known method except for using polyacrylate or polymethacrylate of polyalkylene polyol.
Regarding its production method, first, a monofunctional compound having a nitrile group and a crosslinking agent are reacted to produce a crosslinked copolymer having a nitrile group. As the monofunctional compound having a nitrile group, acrylonitrile, methacrylonitrile, chloroacrylonitrile, vinylidene cyanide, crotonitrile, 2-cyanoethyl acrylate, 2-cyanoethyl methacrylate, etc. are used. Also,
Bis(β-cyanoethyl)aminomethylstyrene, bis(β-cyanoethyl)aminomethylstyrene, etc. can also be used. These are made by chloromethylating styrene using a conventional method, and then bis(β
-cyanoethyl)amine and bis(cyanomethyl)
It can be obtained by reacting with an amine. Usually acrylonitrile or methacrylonitrile is used. These nitriles are 2
You may use a mixture of two or more species. Nitriles usually account for 10-90% (by weight) of the monomers, preferably 40-90% (by weight) of the monomers.
It accounts for 80 (weight)%. As the multifunctional compound which is a crosslinking agent, polyacrylate or polymethacrylate of a polyalkylene polyol having an alkylene group having 2 to 4 carbon atoms and 2 to 14 alkylene groups is used. When these are used as crosslinking agents, the reaction rate when converting nitrile groups into amidoxime groups is good, and the adsorption rate of uranium is extremely high. Usually 2 to 14 as polyalkylene polyol
A polyalkylene diol or polyalkylene triol having 2 alkylene groups is used. Furthermore, polyalkylene polyols having a large number of alkylene groups can also be used, but polyalkylene polyols having a large number of alkylene groups generally have a large affinity for water, making suspension polymerization using water as a dispersion medium difficult. Preferred polyalkylene polyols are ethylene glycol, 1,2-propylene glycol or
1.2-Butylene glycol oligomer or
These glycols are added to di- or tri-functional compounds such as glycerin. These polyalkylene polyols are then esterified with (meth)acrylic acid to form di- or tri(meth)
Use acrylate. These poly(meth)acrates usually represent 10-90% (by weight) of the monomers, preferably 20-60% (by weight). In the present invention, when producing a copolymer having a nitrile group, the above monofunctional compound having a nitrile group and an alkylene group having 2 to 4 carbon atoms are used.
In addition to the poly(meth)acrylate of the polyalkylene polyol having 2 to 14 alkylene groups, other monomers that can be copolymerized with these may be coexisting, if desired. However, in order to increase the adsorption capacity of the resin having amidoxime groups finally obtained, it is preferable to carry out the polymerization without coexistence of other copolymer components. Copolymerization of a monofunctional compound having a nitrile group with a poly(meth)acrylate of a polyalkylene polyol having an alkylene group having 2 to 4 carbon atoms and 2 to 14 alkylene groups is carried out by a conventional method. . Usually, a mixed solution of the two in which a polymerization initiator such as benzoyl peroxide is dissolved is dispersed in water, and spherical particles are produced by suspension polymerization. Preferably toluene, dichloroethane, n-
A monomer and a polymerization initiator are dissolved in an organic solvent such as heptane, and suspension polymerization is performed to produce porous spherical particles. It is preferable to add a dispersion stabilizer such as polyvinyl alcohol to water, which is a dispersion medium. At the same time, it is preferable to include a water-soluble salt such as sodium chloride to prevent the monomer from dissolving in water. The thus obtained copolymer having nitrile groups is then reacted with hydroxylamine in a conventional manner to convert the nitrile groups into amidoxime groups. Usually, the above nitrile group-containing copolymer is added to a water or methanol solution of hydroxymamine, and the reaction is carried out by heating at 40 to 100°C for several hours to more than ten hours. The amount of hydroxylamine used may be equimolar to the amount of nitrile groups in the copolymer. The uranium adsorption and refining operations in the present invention are carried out by conventional methods. Usually, a solution containing uranium is passed through a resin column filled with the above resin to adsorb uranium onto the resin, then a desorbing agent such as hydrochloric acid is passed through to dissolve 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 resin used in the method of the present invention exhibits a higher uranium adsorption rate than conventional resins even as it is, but if it is immersed in an alkaline aqueous solution to swell before being used for uranium adsorption, it can achieve an even higher uranium adsorption rate. show. As explained in detail above, according to the present invention, by using a resin containing poly(meth)acrylate of polyalkylene polyol as a crosslinking agent, uranium can be efficiently extracted even from dilute solutions such as seawater. . 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. In addition, the manufacturing method of the resin used in the examples is as follows. Resin (A) Dimethacrylate of polyethylene glycol (average molecular weight 200) (manufactured by Shin Nakamura Chemical Co., Ltd., trade name NK)
Ester-4G) 40g, acrylonitrile 60g,
A mixed solution of 1 g of benzoyl peroxide and 100 g of toluene was dispersed in an aqueous solution in which 0.1 g of polyvinyl alcohol and 24 g of common salt were dissolved in 500 g of water to form a suspension. A polymerization reaction was carried out at 70° C. for 8 hours while stirring this suspension. After cooling to room temperature, rinse thoroughly with water and heat at 80℃ for 8 hours.
Air-dried for an hour. 85 g of spherical particles with a particle size of approximately 300-1000 microns were obtained. 50 g of the above resin was placed in 500 ml of methanol solution containing 0.5 mol of hydroxylamine, and reacted with stirring at 60° C. for 6 hours. After cooling to room temperature, it was washed with water until hydroxylamine was no longer detected. 240 ml of wet resin with amidoxime groups were obtained. Resin (B) Aqueous solution containing 20ml of 2% gelatin solution, 5g of precipitated calcium carbonate, and 30g of sodium sulfate.
500 ml of industrial divinylbenzene (purity 56.5
%), 50 g of acrylonitrile, 1 g of benzoyl peroxide, and 62 g of toluene.
The mixture was stirred to form a suspension. While stirring this, 60
The polymerization reaction was carried out by holding the mixture at 90°C for 3 hours, at 70°C for 1 hour, and at 90°C for 1 hour. After cooling to room temperature, it was filtered, thoroughly washed with water, and dried under ventilation at 80°C for 8 hours. 85 g of spherical particles with a particle size of approximately 300-1000 microns were obtained. 50 g of the above resin was reacted with hydroxylamine in exactly the same manner as in the case of resin (A) to obtain 145 ml of a wet resin having amidoxime groups. Resin (C) Add 0.1 g of a mixed solution of 40 g of ethylene glycol dimethacrylate, 60 g of acrylonitrile, 1 g of benzoyl peroxide, and 100 g of toluene to 500 g of water.
of polyvinyl alcohol and 24 g of common salt were dispersed in an aqueous solution to form a suspension. A polymerization reaction was carried out at 70° C. for 8 hours while stirring this suspension. After cooling to room temperature, it was filtered, thoroughly washed with water, and dried under ventilation at 80°C for 8 hours. 87 g of spherical particles with a particle size of approximately 300-1000 μm were obtained. 50 g of the above resin was reacted with hydroxylamine in exactly the same manner as in the case of resin (A) to obtain 193 ml of a wet resin having amidoxime groups. Example 1 A column having an inner diameter of 25 mm and a height of 250 mm was filled with 20 ml of resin, and seawater was passed through the column in an upward flow at the space velocity shown in Table 1. Figure 1 shows the relationship between the liquid passage time and the amount of uranium adsorbed per unit weight (dry weight) of the resin. Note that the amount of uranium adsorbed is the amount of uranium adsorbed by the resin.
The uranium was determined by heating and boiling 20 to 50 mg (dry weight) in 30 ml of 1N hydrochloric acid for 1 hour to elute the uranium, and quantifying the uranium in the eluate using the fluorescence method. Regarding the relationship between the uranium adsorption rate and the space velocity, when the space velocity becomes 150 or more, the uranium adsorption rate hardly changes.

[Table] *1 Swelling treatment was carried out by immersing 20 ml of resin (A) in 1N caustic soda at room temperature for 1 hour (this treatment swelled the resin to approximately 140 ml, but when immersed in seawater it It contracted to 78 ml. Furthermore, it contracted to about 20 ml when treated with 1N hydrochloric acid after adsorbing uranium.) Example 2 300 ml of resin (A) was packed into a column with an inner diameter of 70 mm and a height of 600 mm, and SV = 100 hr ^-1 Seawater was passed in an upward flow for about 10 days. 30ml of the resin that has adsorbed uranium in this way is packed together with seawater into a column with an inner diameter of 15mm and a height of 300mm, and 1N hydrochloric acid is added to it for about 20ml of
The uranium was desorbed overnight at ℃, SV = 5 hr ^-1 in a downward flow. The results are shown in Figure 2.

[Brief explanation of the drawing]

FIG. 1 is a graph showing an example of the relationship between seawater passage time and uranium adsorption amount. In the figure, the vertical axis shows the amount of uranium adsorbed (μg-uranium/g-dry resin), and the horizontal axis shows the number of days of ammo. Further, the numbers in the figure correspond to the numbers in Table 1. FIG. 2 is a graph showing changes in uranium concentration in the effluent when uranium is eluted from a resin that has adsorbed uranium. In the figure, the vertical axis shows the resin concentration in the effluent, and the horizontal axis shows the amount of the effluent.

Claims (1)

[Scope of Claims] 1. At least one polyalkylene polyol selected from the group consisting of polyacrylate and polymethacrylate having an alkylene group having 2 to 4 carbon atoms and 2 to 14 alkylene groups. A solution containing uranium is brought into contact with a resin having a structure in which a crosslinked copolymer of a monoductal compound and a monotubular compound is bonded to the skeleton and an amidoxime group is bonded to the monotubular compound portion of the skeleton. A method for collecting uranium from a dilute solution, which is characterized by adsorbing uranium onto a resin. 2. The method for collecting uranium according to claim 1, wherein the polyalkylene polyol is a polyalkylene diol or a polyalkylene triol. 3. The method for collecting uranium according to claim 1 or 2, characterized in that the resin is treated with an alkaline aqueous solution to swell it and then brought into contact with a solution containing uranium.