JPS6135255B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for collecting uranium, and more specifically, the present invention relates to a method for collecting uranium, and more specifically, a dilute uranium solution using a specific organic polymer adsorbent containing fluorine atoms and phosphorus atoms, for example, to effectively adsorb trace amounts of uranium dissolved in seawater. Regarding the method of collection. Conventionally, various methods have been considered for collecting uranium from seawater, and adsorption methods using various adsorbents are considered advantageous in collecting uranium from vast amounts of seawater. Adsorption materials for collecting uranium from such dilute solutions include:
Inorganic compounds such as titanic acid, aluminum hydroxide, iron hydroxide, lead sulfide, and basic zinc carbonate are considered effective; for example, a method in which titanic acid, which has relatively high adsorption performance, is supported on activated carbon as an adsorbent. (See Japanese Patent Publication No. 49-648, etc.) has been proposed as a highly practical method. Therefore, the above-mentioned inorganic adsorbents are difficult to mold and easily fractured compared to organic adsorbents, and furthermore, uranium is eluted during repeated contact with seawater and the elution process of adsorbed uranium. The disadvantage is that the rate of wear and tear is high. On the other hand, as organic adsorbents, arsonic acid type resins (see British Patent No. 948962, etc.) and hydroxyphenyl compound-formaldehyde condensates having a phosphonic acid group bonded to an aromatic ring (Japanese Unexamined Patent Publication No. 114510/1989) Publications, etc.〓〓〓〓
) have been proposed, but they are not necessarily practically satisfactory in terms of problems such as the disadvantages of using arsenic compounds, which are toxic substances, as raw materials, uranium adsorption ability, and durability. Based on the recognition of the above-mentioned problems, the present inventor has conducted various studies and examinations, and has found that organic polymer materials such as fluoropolymers containing phosphoric acid groups or phosphonic acid groups can be used as adsorbents for collecting uranium. We have obtained new knowledge that is extremely superior. That is,
Unlike inorganic materials, such organic polymer materials have excellent wear resistance and can provide stable adsorption performance, and the introduction of fluorine atoms increases the activity of ion exchange groups such as phosphoric acid groups, making it possible to absorb uranium. The adsorption capacity, especially the adsorption rate, can be significantly increased, and since it contains fluorine, there is very little wear and tear due to elution, etc., and it has excellent durability, especially against long-term contact with seawater and repeated desorption processes of adsorbed uranium. It is an advantageous uranium adsorbent for applications such as Moreover, since it is an organic polymer, it can be molded into any shape and size.In particular, by creating a porous structure, the surface area can be increased and liquid can penetrate easily, making it suitable for ion exchange. It is also advantageous in that it can increase the utilization efficiency of the group. Thus, the present invention has been completed based on the above findings, and is characterized in that it uses an organic polymer material containing fluorine atoms and phosphorus atoms in its molecules as an adsorbent. This provides a new method for collecting. In the present invention, an organic polymer material containing fluorine atoms and phosphorus atoms in its molecules is used as an adsorbent, and various organic polymer materials can be exemplified as such organic polymer materials. Generally, a fluorine-containing organic polymer material having an ion exchange group containing a phosphorus atom is preferably employed. The fluorine atom is
It may be contained in either the main chain or the side chain of the organic polymer, for example, a fluoropolymer containing a phosphorus atom-containing ion exchange group, or a fluorine atom and a phosphorus atom in a non-fluorinated main chain. There are some that have an ion exchange group side chain containing both. Of course, both the main chain and the side chain may contain fluorine atoms, and furthermore, it may be a perfluoropolymer having an ion exchange group containing a phosphorus atom. Examples of the ion exchange group containing a phosphorus atom include a phosphonic acid group, a phosphoric acid monoester group, and a phosphinic acid group. The specific organic polymer material as described above can be manufactured by various means. For example, polymerization, copolymerization, condensation using compounds containing fluorine atoms and phosphorus atoms, various polymerization reactions of fluorine-containing compounds and phosphorus-containing compounds, and addition of fluorine atoms to non-fluorinated polymer materials. and a reaction of introducing a phosphorus atom-containing compound, a reaction of introducing a phosphorus atom-containing compound or a phosphorus atom and a fluorine atom-containing compound into a fluorinated polymer material, and the like. Such an organic polymer material is formed into an arbitrary shape and used as an adsorbent in the present invention, but of course, a fluorine atom-containing compound can be added to the organic polymer material which has been formed into an arbitrary shape in advance. Alternatively, an adsorbent may be obtained by introducing a phosphorus atom-containing compound. In a preferred embodiment of the present invention, the concentration of ion exchange groups containing phosphorus atoms in the polymer is set to
The amount is 0.2 milliequivalent or more, preferably 0.4 milliequivalent or more per g. In addition, the fluorine atom content in the organic polymer material can be varied over a wide range depending on its content, but it is usually at least the same number as the phosphorus atoms contained, particularly 2 fluorine atoms per phosphorus atom. The amount containing the above fluorine atoms is suitable. In the present invention, it is desirable that the side chain having a phosphorus atom-containing ion exchange group contains at least the same number of fluorine atoms as the number of phosphorus atoms, especially a multiple or more, and the main chain of the polymer contains fluorine atoms. may or may not be contained. As a specific example of the means for producing the specific adsorbent used in the present invention, the following method may be exemplified. For example, there is a method in which a polystyrene polymer is used and a side chain containing a fluorine atom and a phosphorus atom is introduced in the following steps. 〓〓〓〓
Furthermore, using a fluoropolymer containing double bonds in the side chain, phosphorous acid (H ₃ PO ₃ ) or dialkyl phosphite [HP(O)(OR) _{2 ]} , preferably in the presence of a radical generator, can be used. (R: alkyl group)]
An example of this method is to introduce a phosphonic acid group by reacting with the following formula. (X, Y, and Z are H or F, and R is H or an alkyl group) When using polystyrene polymers, not only styrene homopolymers but also various styrene copolymers can be used. , crosslinked with 0.1 to 10% divinylbenzene is one preferred example. Therefore, it is employed in various shapes such as granules and fibers, and porous bead shapes are usually preferred.
When introducing a fluorine-containing phosphonic acid group, etc., it is common to form an introduction site by chloromethylation, bromination, etc., and then react this with a fluorine-containing compound and a phosphorus-containing compound. For example, by reacting chloromethylated polystyrene with a fluorine-containing diol and then reacting with phosphorus oxychloride, or by reacting brominated polystyrene with diiodofluoroalkane, and then reacting with triethylphosphine or sodium ester of dialkyl phosphite. It can be introduced by reacting with salt or the like. When carrying out the collection of uranium according to the present invention, a specific organic polymer material as described above is used as an adsorbent, and an appropriate method is used to collect uranium from a dilute uranium solution, such as a column method, a slurry method, a fluidized bed method, or a uranium-containing solution. Uranium is adsorbed by simply immersing the adsorbent in the water. The shape of the adsorbent may be arbitrary, for example, granular, fibrous, scale-like, etc., but it is generally preferable that the adsorbent has a large specific surface area because it has a high adsorption rate. In particular, porous beads have the advantage of having a large surface area, easy penetration of liquid, and fast uranium adsorption rate. The diameter of the beads is not particularly limited, but is 10 to 200 mesh, preferably 20 to 50 mesh.
Metsushi's ones are easy to handle. Desorption and recovery of adsorbed uranium can be performed by conventional methods. The method of the present invention is suitable for collecting uranium from dilute uranium solutions with very low concentrations, especially seawater, but also from uranium solutions with a wide range of concentrations, from low concentrations of a few ppm to relatively high concentrations of several 100 ppm. can be,
Adsorption enrichment of uranium can also be carried out. Next, embodiments of the present invention will be described in more detail, but it goes without saying that the present invention is not limited by such explanations. In the following examples, the ion exchange group concentration of the adsorbent was measured by elemental analysis of phosphorus atoms and titration with an alkali. Reference example 1 Cross-linked polystyrene beads (ROHM, AN〓〓〓〓
(Haas “Amberlight” XE-305)
Using 10.4g, chloromethylation was performed using a known method.
14.4 g of poly(P-chlorostyrene) was obtained. Analysis revealed that 19.0% (5.36 mmol/g) of chlorine had been introduced. 3.87 g of the thus obtained chloromethylated polystyrene beads,
Tetrahydrofuran 60ml, dimethylformamide
20 ml and 17.6 g of 2,2,3,3,4,4-hexafluoro-1,5-pentanediol. The mixture is cooled to −20° C. and 1.5 gr of sodium hydride is added in portions under a nitrogen atmosphere. After adding the entire amount, leave at room temperature for 2 hours at 50°C.
Stir for 3 hours at 80°C and finally for 6 hours at 80°C. After cooling, it is filtered and washed with a water/tetrahydrofuran mixture and then with tetrahydrofuran. After drying under reduced pressure, 6.2 g of fluorine-containing beads were obtained. The fluorine content was 20.4% (10.7 milliequivalents/g) as a result of elemental analysis. In the infrared absorption spectrum, OH at 3400 cm ^-1 and 1150 cm ^-1 and 1115 cm
^-1 showed absorption based on CF ₂ . Next, 882 mg of the fluorine-containing beads were suspended in 10 ml of tetrahydrofuran and 1 ml of triethylamine. The mixture is cooled to -20°C, 3.5 ml of phosphorus oxychloride is added and stirred at room temperature for 6 hours. After the beads are filtered and washed with water/tetrahydrofuran and tetrahydrofuran, they are hydrolyzed with 10 ml of a 2:1 dioxane/pyridine mixture at room temperature. Strain the beads, water/tetrahydrofuran,
After thoroughly washing with tetrahydrofuran, dry under reduced pressure. 1.34 g of ion exchange resin containing phosphoric acid groups was obtained. In the infrared absorption spectrum, 2700cm
^-1 , 1150cm ^-1 , 1115cm ^-1 , and 1010cm ^-1 . The content of phosphate groups was 0.9 meq/g. Reference example 2 (a) 21.2 g of cross-linked polystyrene beads (Rohm & Haas “Amberlite”)
XE-305) by a known method,
30.6 g of poly(P-bromstyrene) was obtained. The bromine content was 29.5% (3.69meq/g). (b) Suspend 2.1 g of beads from (a) above in 40 ml of benzene, lithiate using n-butyllithium by a known method, and then heat the suspension at -70°C to 1,8-diiodo-3,3. 12.5 g of 4.4.5.5.6.6-octafluorooctane are treated with 50 ml of THF and the resulting mixture is stirred at room temperature for 15 hours.
Finally, heat to 80℃ for 2 hours. After cooling, the beads are filtered and washed with water/THF, THF, and methylene chloride. Drying under reduced pressure yielded 3.0 g of dry beads. 1220, 1170, 1120 in infrared absorption
Shows characteristic absorption at cm ^-1 . The content of iodine and fluorine is 14.6% (1.2mep/g) and 12.7%, respectively.
(6.7meq/g). (c) 846 mg of the beads from (b) above are suspended in 2.0 ml of triethylphosphine and heated to 160°C for 18 hours under a nitrogen stream. After filtering and washing the beads with THF, add 5 ml of a 2:1 dioxane-concentrated hydrochloric acid mixture.
and reflux for 3 hours. Filter the beads, wash with water/THF, THF, and dry under vacuum. 783 mg of ion exchange resin containing phosphonic acid groups was obtained. The content of phosphonic acid groups is 0.4me
It was q/g. Example 1 A uranyl nitrate aqueous solution with a uranium concentration of 1000 ppm was mixed with model seawater (NaCl concentration 23000 ppm,
5000ppm, _Na2SO4 concentration _4000ppm , _CaCl2 concentration
1000ppm) and adjust the pH of the solution to 8.1 with an aqueous sodium carbonate solution. Put 100 ml of this solution (uranium concentration 1.0 ppm, equivalent to about 300 times the uranium concentration of natural seawater) and 53 mg of the resin from Reference Example 1 into a 100 ml Erlenmeyer flask, and let it cool at room temperature.
After shaking for 62 hours, the uranium concentration of the liquid from which the resin was removed was measured, and the amount of uranium adsorbed by the resin was calculated from this. As a result, it was found that 3930μg of uranium was adsorbed per gram of resin. Example 2 Under the same conditions as Example 1, 50 mg of the resin of Reference Example 2
As a result of conducting a uranium adsorption experiment using the resin, 1520 μg of uranium was adsorbed per gram of resin after 62 hours. Examples 3-4 and Comparative Examples 1-2 Adsorbent A (Example 3) manufactured in the same manner as Reference Example 1, Adsorbent B (Example 4) manufactured in the same manner as Reference Example 2, Amber Light”XE−305
C adsorbent (Comparative Example 1) consisting of “Amberlite” XE-305

[Formula] Group introduced〓〓〓〓
A uranium adsorption experiment similar to that in Example 1 was conducted using four types of adsorbent: D adsorbent (Comparative Example 2). The results obtained after 30 hours of shaking are summarized in Table 1 below.

[Table] 〓〓〓〓

Claims (1)

[Scope of Claims] 1. A method for collecting uranium from a dilute uranium solution, characterized in that an organic polymer material containing fluorine atoms and phosphorus atoms in its molecules is used as an adsorbent. 2 Claim 1 in which the organic polymer material is a fluoropolymer having an ion exchange group containing a phosphorus atom
uranium collection method described in section. 3. The method for collecting uranium according to claim 1, wherein the dilute uranium solution is seawater. 4. The method for collecting uranium according to claim 1, wherein the adsorbent has a porous structure. 5. The method for collecting uranium according to claim 1 or 2, wherein the organic polymer material is a polystyrene polymer having a fluorine-containing phosphonic acid group. 6. The method for collecting uranium according to claim 1 or 2, wherein the organic polymer material is a polystyrene polymer having a fluorine-containing phosphate ester group. 7 Claim 5 or 6 which is a polystyrene bead crosslinked with a polystyrene polymer
uranium collection method described in section. 8 A polystyrene polymer with a porous structure
8. The method for collecting uranium according to claim 7, which uses an organic polymer material crosslinked with 0.1 to 10% divinylbenzene. 9. The method for collecting uranium according to claim 2, wherein the concentration of ion exchange groups containing phosphorus atoms is 0.2 milliequivalent or more per gram of the organic polymer material.