Method for collecting uranium from seawater and method for producing uranium raw materials

Abstract

To provide a ligand for collecting seawater uranium which can selectively collect uranium in seawater highly efficiently even at near 8 which is pH condition of seawater, a seawater uranium collection method using the ligand, and a method for producing a uranium raw material.SOLUTION: A ligand for collecting seawater uranium of the present invention is a ligand that selectively forms a metal complex with uranium in seawater, and collects the uranium, and is a compound expressed in the following general formula (1), ion derived from the compound, and one or more selected from the group consisting of polymers having the structures of the compound or the ion, where complex stability constant (logβ11) of the metal complex in seawater is 10 or more. [formula 1] (in general formula (1), R1 to R13 is as described in the text)SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention ,sea This paper relates to a method for collecting uranium water and a method for producing uranium raw materials. [Background technology]

[0002] Among natural uranium resources, the ocean contains approximately 4.5 billion tons of dissolved uranium, nearly 1,000 times the amount estimated to be found in mineral resources, making seawater uranium resources of great interest. However, the uranium concentration in seawater is extremely low, and the concentration of other metal ions, such as sodium salts, is high. Therefore, technologies for efficiently and effectively extracting uranium from seawater are being developed.

[0003] For example, Patent Document 1 discloses a functionalized porous organic polymer having multiple uranium-collecting ligands such as amidoxime, and describes a composition for efficiently extracting uranium from wastewater, seawater, or other water sources. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Special Publication No. 2021-510624 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, while the optimal conditions for uranium capture in amidoxime resin containing amidoxime groups as ligands are pH 4-6, the pH of seawater is around 8. As a result, when capturing uranium from seawater, a significant decrease in capture performance is unavoidable. Therefore, the utilization efficiency of the amidoxime groups introduced into the resin for uranium capture is less than 1%, and it does not satisfy the performance requirements for a uranium capture resin.

[0006] The present invention has been made to solve the above problems, and an object thereof is to provide a ligand for collecting uranium in seawater that can selectively collect uranium in seawater with high efficiency even at a pH condition of seawater around 8. Another object is to provide a method for collecting uranium in seawater using the ligand for collecting uranium in seawater, and a method for producing a uranium raw material.

Means for Solving the Problems

[0007] The present invention includes the following aspects. [1] A ligand that collects the uranium by selectively forming a complex with the uranium in seawater, which is one or more selected from the group consisting of a compound represented by the following general formula (1), an ion derived from the compound, and a polymer having the structure of the compound or the ion, and the common logarithm (logβ 11 ) of the complex stability constant of the complex in seawater is 21 or more. A ligand for collecting uranium in seawater.

Chemical formula

[0008] The present invention aims to provide a ligand for collecting uranium from seawater, a method for collecting uranium from seawater, and a method for producing uranium raw materials, which can selectively collect uranium from seawater with high efficiency even at seawater pH conditions around 8. Furthermore, it is possible to provide a method for collecting uranium from seawater using the ligand for collecting uranium from seawater, and a method for producing uranium raw materials. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows the ultraviolet-visible light absorption spectrum of a uranium complex (UO2(saldian)). [Figure 2] This is a distribution map of UO2 2+-saldian2- complexes. [Figure 3] This graph plots the predicted values ​​of ΔE (strength of electron-donating → magnitude of complex stability constant) when various functional groups are introduced. [Figure 4] This figure shows the infrared absorption spectra of chloromethyl polystyrene resin, H2saldian, H2saldian(-(CH2)2-NH) resin, and H2saldian resin. [Modes for carrying out the invention]

[0010] The embodiments of the present invention will be described in detail below. However, the present invention is not limited to the embodiments shown below.

[0011] (Ligand for collecting uranium from seawater) A ligand for collecting uranium from seawater according to one embodiment of the present invention (hereinafter sometimes referred to as "the uranium collecting ligand of this embodiment" or "the ligand of this embodiment") is a ligand that collects uranium in seawater by selectively forming a complex with it. It is one or more selected from the group consisting of a compound represented by the following general formula (1), an ion derived from the compound, and a polymer having the structure of the compound or the ion. The common logarithm (logβ) of the complex stability constant of the complex in seawater 11 ) is 21 or greater.

[0012] [ka] (In general formula (1), R 1 ~R 13 These terms independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a dialkylamino group composed of an alkyl group having 1 to 5 carbon atoms, a nitro group, a perfluoroalkyl group composed of 1 to 5 carbon atoms, and a halogen group.

[0013] <Compounds represented by general formula (1)> In the compound represented by the general formula (1) above according to this embodiment, in the general formula (1), the R 1 ~R 10 Each of these groups independently preferably represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a dialkylamino group composed of an alkyl group having 1 to 5 carbon atoms, or a halogen group; each of these groups independently preferably represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a dialkylamino group composed of an alkyl group having 1 to 3 carbon atoms, or a halogen group; each of these groups independently is even more preferably a hydrogen atom, a methyl group, or an ethyl group, and most preferably a hydrogen atom.

[0014] In the compound represented by the general formula (1) above according to this embodiment, in the general formula (1), the R 11 ~R 13 Each of these preferably independently represents a hydrogen atom and an alkyl group having 1 to 5 carbon atoms; each more preferably independently represents a hydrogen atom and an alkyl group having 1 to 3 carbon atoms; and each more preferably independently represents a hydrogen atom and a methyl group.

[0015] In other words, the uranium collecting ligand of this embodiment is one or more selected from the group consisting of a compound represented by the above general formula (1), an ion derived from the compound, and a polymer having the structure of the compound or the ion, wherein in the above general formula (1), R 1 ~R 2 R represents a hydrogen atom; 3 ~R 4 Each of these independently represents a hydrogen atom or a methyl group, and R 5 ~R 7 Preferably, each of these ligands independently represents either a hydrogen atom or a methyl group.

[0016] Specific examples of compounds represented by the general formula (1) in this embodiment include the compounds represented by the following formula (2) (Ia to Ig) and the compounds represented by the following formula (3) (IIa to IIg).

[0017] [ka]

[0018] [ka]

[0019] Among the above compounds (Ia to Ig) and compounds (IIa to IIg), compound (Ia) (compound name: N,N'-bis(2-hydroxybenzyl)diethylenetriamine (sometimes called "H2saldian")) or compound (IIa) is preferred.

[0020] <Ions derived from compounds represented by general formula (1)> Examples of ions derived from the compound represented by general formula (1) according to this embodiment (hereinafter sometimes referred to as the ions of this embodiment) include a divalent anion having two phenoxy ion groups, represented by formula (4) below, which is obtained by removing hydrogen ions from two phenolic hydroxyl groups of the compound represented by general formula (1) above (sometimes referred to as the ion of formula (4)).

[0021] [ka]

[0022] (In formula (4), R 1 ~R 13 This is R in the general formula (1) above. 1 ~R 13 (It has the same meaning.)

[0023] In the ion of this embodiment represented by formula (4) above, R in formula (4) 1 ~R 13 A preferred example is R in the general formula (1) above. 1 ~R 13 It is the same as this.

[0024] Specific examples of the ions represented by formula (4) in this embodiment include the ions (IIIa to Ig) represented by the following formula (5) and the ions (IVa to IVg) represented by the following formula (6).

[0025] [ka]

[0026] [ka]

[0027] <Synthesis method of the compound represented by general formula (1)> The method for synthesizing the compound represented by general formula (1) according to this embodiment will be explained using the method for synthesizing the compounds (Ia to Ig) represented by formula (2) above. The compounds (Ia to Ig) shown in formula (2) above can be synthesized, for example, via the compounds (Va to Vg) represented by formula (7) below.

[0028] [ka]

[0029] For example, compound 2 can be synthesized via compound 7, as shown in Scheme 1 below. [ka]

[0030] The compound represented by formula (7) can be synthesized by reacting a derivative of compound 8 (salicylaldehyde) with compound 9 (diethylenetriamine) using the method disclosed in Non-Patent Document 1 below, as shown in Scheme 2 below. (Non-patent document 1: T. Takeyama et al., Effects of Substituents on the Molecular Structure and Redox Behavior of Uranyl(V / VI) Complexes with N3O2-Donating Schiff Base Ligands, Inorg. Chem. 2021, 60, 11435-11449.)

[0031] [ka]

[0032] Alternatively, the intermediate product compound 7 may not be isolated, and the reactions in schemes 1 and 2 may proceed simultaneously.

[0033] <A polymer having the structure of a compound or ion represented by general formula (1)> A polymer compound having a structure derived from the compound represented by general formula (1) or its ion according to this embodiment (hereinafter sometimes referred to as the polymer or resin of this embodiment) is, for example, a polymer compound in which any part of the compound represented by general formula (1) is bonded to the polymer main chain or side chain. For example, a polymer represented by general formula (10) below, which has a structure derived from the compound represented by general formula (1), can be mentioned (sometimes referred to as the polymer of general formula (10)).

[0034] [ka]

[0035] (In formula (10), R 1 ~R 13 This is R in the general formula (1) above. 1 ~R 13 It has the same meaning, however, R 1 ~R 13 One of the substituents is a single bond or a divalent substituent. L represents a single bond or a divalent linking group. The above polymer is a linear polymer or a crosslinked (branched) polymer.

[0036] R in equation (10) 1 ~R 13 A preferred example is the same as the preferred example described for the compound represented by general formula (1).

[0037] The above linking group is preferably a linking group selected from the group consisting of -CO-, -O-, -NH-, a divalent aliphatic group; a divalent aromatic group; and combinations thereof. Examples of divalent aliphatic groups include alkylene groups (preferably having 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms), and examples of divalent aromatic groups include arylene groups such as phenylene and xylylene groups (preferably having 6 to 15 carbon atoms, more preferably 6 to 10 carbon atoms). L is, for example, -(CH2)n-NH-(CH2)m-(n=1 to 3, m=1 to 3).

[0038] Examples of the polymers mentioned above include olefin resins such as polyethylene, polypropylene, polystyrene, and polyvinyl chloride; acrylic resins such as polymethyl methacrylate and polymethyl methacrylate; polyimides; polyamides such as nylon; polyethers such as polyacetal; polyesters such as polycarbonate and polyethylene terephthalate; and crystalline plastics such as polyphenylene sulfide.

[0039] Examples of polymer synthesis methods in this embodiment include a synthesis method that includes the step of introducing substituents containing a structure derived from the compound of general formula (1) in this embodiment into the raw materials of various polymers, and a step of polymerization using a conventional polymer synthesis method. Another example of polymer synthesis methods in this embodiment includes a synthesis method that includes the step of introducing substituents containing a structure derived from the compound of general formula (1) in this embodiment into the main chain or side chain of a conventional polymer.

[0040] For example, in synthesis examples 7 and 8 described later, H2saldian(-(CH2)2-NH) resin represented by formula (14) and H2saldian resin represented by formula (15) described later were synthesized. In the above H2saldian(-(CH2)2-NH) resin and H2saldian resin, in the above general formula (10), the polymer is polystyrene, L is -CH2-NH-(CH2)2- or -CH2-, and Compound-1 is H2saldian, which is compound (Ia) represented by formula (2) above.

[0041] <X> In seawater, a complex can be selectively formed between the uranium-collecting ligand of this embodiment and uranium. When the uranium-collecting ligand of this embodiment is compound (Ia) or an ion of that compound, an example of complex formation between ion (IIIa) and uranium will be used for explanation. As shown in Scheme 3 below, compound (Ia) and UO2(CO3)3 4- The complex (UO2(saldian)) is obtained as a reaction product of the divalent ion (IIIa) of compound (Ia) and the divalent ion UO2 2+ It is a complex with [the other component].

[0042] [ka]

[0043] As shown in the examples described later, UO2 under simulated seawater conditions (0.5M NaCl) 2+ and saldian 2- Complex formation was confirmed. In 0.5M NaCl, the common logarithm (logβ) of the complex stability constant of the metal complex (UO2(saldian)) shown by formulas (I) and (II) below was determined. 11 ) is 27.5. logβ 11 The method for determining this will be explained in the examples. UO2 2+ + saldian 2- = UO2(saldian) (I) logβ11 = 27.5 (II)

[0044] Using the compound represented by the general formula (1) in this embodiment, similarly, the ion of that compound, shown by formula (4), and UO2 2+ A complex is formed with it, and the common logarithm of the stability constant of that complex (logβ) 11 ) is 21 or greater.

[0045] Furthermore, as shown in the examples described later, compound (Ia) and other metal ions, for example, Al 3+ VO2 + Ni 2+ ,Cu 2+ Zn 2+ , Cd 2+ The common logarithm (logβ) of the stability constant of these metal complexes is used for their complex stability constants. 11 All of these values ​​are less than 21. Furthermore, it is preferable that compound (Ia) or its ion (IIIa) does not form a complex with alkali metal ions or alkaline earth metal ions.

[0046] In other words, when using compound (Ia) or its ion (IIIa), uranium (UO2) forms complexes more readily than other metal ions. 2+ The complex formation with ) is at least 1x10 6.5 It is twice as easy (27.5 - 21 = 6.5). Therefore, even in seawater, uranium (UO2) can be obtained with high selectivity. 2+ ) can form a complex.

[0047] Furthermore, the ligand and uranium (UO2) reported in Non-Patent Document 2 below 2+ The stability constant Logβ of the metal complexes that form the ) is 21 or less in all cases, as shown below. Benzamidoxime: 12.4 Acetamidoxime: 13.6 1,10-Phenanthroline-2,9-dicarboxylic acid: 16.5 Glutarimidodioxime: 17.8 2,6-Bis[hydroxy(methyl)amino]-4-morpholino-1,3,5-triazine:17.47 (Non-patent document 2: Polyhedron 2016, 109, 81-91; Dalton Trans. 2012, 41, 11579-11586; Nat. Commun. 2019, 10, 819.)

[0048] (Method for collecting uranium from seawater) The method for collecting uranium from seawater according to this embodiment (hereinafter sometimes referred to as the collection method of this embodiment) collects uranium (for example, UO2) from seawater. 2+ The method for capturing uranium involves selectively forming a metal complex with one or more selected from the group consisting of a compound represented by the above general formula (1), an ion derived from the compound, and a polymer having the structure of the compound or the ion.

[0049] [ka]

[0050] Preferred embodiments of the compound represented by the above general formula (1) or ions derived from the compound are the same as those described in "Ligands for collecting uranium in seawater".

[0051] The collection method of this embodiment can directly use the compound represented by the above general formula (1) or ions derived from that compound, but it may also use a compound that has the compound represented by the above general formula (1) or ions derived from that compound as part of its structure. For example, a polymer (resin) that has the compound represented by the above general formula (1) or ions derived from that compound as part of its structure can be used. In the present invention, a polymer (resin) obtained using the compound represented by the general formula (1) or ions derived from that compound may be referred to as a seawater uranium collection material having the ligand for seawater uranium collection of this embodiment. The seawater uranium collection method of this embodiment is characterized in that the ligand for seawater uranium collection of this embodiment is used to collect uranium (e.g., UO2) in seawater. 2+A process to promote the capture of uranium (for example, UO2) by complex formation, and 2+ Preferably, the process includes a step of recovering the complex (metal complex) formed with )

[0052] (Method of manufacturing uranium raw materials) The method for producing uranium raw materials in this embodiment (hereinafter referred to as the method of this embodiment) involves using uranium (for example, UO2) in seawater. 2+ ) collects and releases uranium (e.g., UO2) in seawater. 2+ This is a method for producing a uranium concentrate that is more than 100 times more concentrated than the uranium concentration. The production method of this embodiment is a method for collecting uranium from seawater using the seawater uranium collection method of this embodiment described above, and a method for adjusting the pH to concentrate uranium (for example, UO2 2+ The process includes a step of releasing uranium from a complex (metal complex) formed with ) [Examples]

[0053] The present invention will be described in detail below with reference to examples. The present invention is not limited in any way by the examples shown below.

[0054] (Evaluation method) <Method for measuring complex stability constant> Simulated seawater with dissolved uranium-collecting ligands (0.5M NaCl + 2.3mM HCO3) - / CO3 2- (pH 8.0) contains various metal ions (UO2 2+ , Al 3+ VO2 + Ni 2+ Cu 2+ Zn 2+ , Cd 2+ Mg 2+ Ca 2+ Sr 2+ Ba 2+ , Zr 4+) was sequentially added so that the metal ion:ligand concentration ratio was 0 to 1.5, and the ultraviolet-visible absorption spectrum was measured each time using an Agilent Cary 3500 ultraviolet-visible spectrophotometer. By analyzing the group of ultraviolet-visible absorption spectra obtained for each metal ion with an equilibrium analysis program, the common logarithm value (logβ 11 ) was determined.

[0055] <Measurement method of separation factor> UO2 2+ 's logβ 11 From each metal ion's logβ 11 By subtracting, the separation factor of UO2 2+ for each metal ion was determined.

[0056] < 1 <Measurement method of 1H NMR> The ligand for uranium collection was dissolved in CDCl3, and the 1 1H NMR spectrum was measured using a JEOL JNM-ECX400 nuclear magnetic resonance apparatus.

[0057] < 13 <Measurement method of 13C NMR> The ligand for uranium collection was dissolved in CDCl3, and the 13 13C NMR spectrum was measured using a JEOL JNM-ECX400 nuclear magnetic resonance apparatus.

[0058] (Synthesis Example 1) "Synthesis of Compound (Va): N,N'-disalicylidene-diethylenetriaminate (H2saldien)" Diethylenetriamine (0.55 g, manufactured by Kanto Chemical Co., Inc.) and salicylaldehyde (1.66 g, manufactured by Fluka) were mixed in ethanol (40 mL). The mixture was refluxed for 40 minutes and then cooled to room temperature. The cooled reaction mixture was evaporated under reduced pressure until almost dry to obtain a pale yellow oily substance.

[0059] (Synthesis Example 2) "Synthesis of H2saldian (Compound (Ia)): N,N'-Bis(2-hydroxybenzyl)diethylenetriamine" While stirring well at room temperature, diethylenetriamine (1.04 mL, 0.984 g, 9.54 mmol) was added dropwise to a THF solution (60 mL) in which salicylaldehyde (2 mL, 2.33 g, 19.1 mmol) was dissolved. This yellow solution was refluxed for 1 hour and then cooled in an ice bath. While stirring well, NaBH(OAc)3 (6.50 g, 30.7 mmol) was gradually added. The yellow suspension was stirred at 0 °C for 30 minutes and then further stirred at room temperature for 1.5 hours. Water (10 mL) was poured into the almost colorless suspension to stop the reaction, and then it was stirred for an additional 15 minutes. After removing THF by evaporation, 7.2 M aqueous NaOH solution was added dropwise to this aqueous mixture to adjust the pH to 8 - 9, and the oil layer was separated from this aqueous mixture. This oily substance was extracted with CH2Cl2 (50 mL), washed with saturated basic brine (20 mL + 3 drops of 7.2 M aqueous NaOH solution), and the separated CH2Cl2 phase was dried over MgSO4. The filtrate was evaporated to obtain H2saldian as a pale yellow oil (1.92 g, 6.09 mmol, 64% yield).

[0060] For the obtained H2saldian 1 1H NMR and 13 13C NMR were measured, and the results are shown below.

[0061] 1 1H NMR (δ / ppm vs. TMS, CDCl3) 7.15 (td, 2 H, Ph-H), 6.98 (dd, 2 H, Ph-H), 6.81 (dd, 2 H, Ph-H), 6.77 (td, 2 H, Ph-H), 4.00 (s, 4 H, Ph-CH2-N), 2.77 (m, 8 H, N-CH2CH2-N).

[0062] 13 13C NMR (δ / ppm vs. TMS, CDCl3) 158.28, 128.84, 128.48, 122.49, 119.08, 116.47, 52.49, 48.47, 48.18.

[0063] (Synthesis Example 3) "Synthesis of H2acetdian (compound (IIa)): N,N'-bis(2-hydroxyphenylethyl)diethylenetriamine" Diethylenetriamine (63 μL, 61 mg, 0.59 mmol) was added dropwise to a THF solution (3 mL) containing 2-hydroxyacetophenone (142 μL, 159 mg, 1.17 mmol) while stirring well at room temperature. This yellow solution was refluxed for 2 hours. After removing the THF by evaporation, the residue was dissolved in AcOH (1 mL). NaBH4 (89 mg, 2.35 mmol) was gradually added while stirring well at room temperature. The pale yellow suspension was stirred at room temperature for 1 hour. The reaction was stopped by adding methanol (1 mL) to the reaction mixture. After removing volatiles by evaporation, water (15 mL) in which Na2CO3 (0.926 g, 8.74 mmol) was dissolved was added, followed by extraction with CH2Cl2 (50 mL). After washing with saturated brine (20 mL), the separated organic layer was dried on MgSO4. The filtrate was evaporated to obtain H2acetdian as a pale yellow oily substance (137 mg, 0.401 mmol, yield 68%).

[0064] H2acetdian has two chiral carbon atoms. A schematic diagram is shown below. Therefore, the products obtained here include (R,R)-, (S,S)-, and (R,S)- isomers. As a result, due to the polymerization of signals generated from nuclei immersed in a similar environment in the diastereoma, 1 H and 13 Several multiplicities were observed in the CNMR spectrum.

[0065] [ka]

[0066] The obtained H2acetdian 1 1H NMR and 13 The 13C NMR spectrum was measured, and the results are shown below.

[0067] 1H NMR (δ / ppm vs. TMS, CDCl3) 7.13 (td, 2 H, Ph-H), 6.96 (d, 2 H, Ph-H), 6.75-6.82 (m, 4 H, Ph-H), 3.90 (quartet, 2 H, Ph-*CHCH3-N), 2.64-2.82 (m, 8 H, N-CH2CH2-N), 1.40-1.54 (m, 6 H, -CH3).

[0068] 13 C NMR (δ / ppm vs. TMS, CDCl3) 157.1-157.4, 127.9-128.6, 126.5-126.9, 118.5-119.8, 116.0-117.6, 59.0-59.5, 48.3-49.0, 46.9-47.5, 22.2-23.9.

[0069] (Synthesis Example 4) "Synthesis of H2saldian-Me3 (compound of formula (12) above)" A mixture of H2saldian (1.92 g, 6.09 mmol) and 30% formaldehyde aqueous solution (2.55 mL, 27.5 mmol) in 35 mL of 1,2-dichloroethane was thoroughly stirred at room temperature for 30 minutes. NaBH(OAc)3 (6.71 g, 31.7 mmol) was gradually added to the reaction mixture, followed by further stirring at room temperature for 1.5 hours. The reaction was stopped by adding water (10 mL) to the reaction mixture. The pH of the aqueous phase was then adjusted to pH 8-9 using a 7.2 M NaOH aqueous solution. After removing the aqueous phase, the organic phase was washed with basic saturated brine (20 mL + 3 drops of 7.2 M NaOH aqueous solution). The separated organic layer was dried over MgSO4, filtered, and evaporated to dry. The resulting brown oil of H2saldian-Me3 crystallized into a white solid at room temperature (1.67 g, 4.67 mmol, 77% yield).

[0070] H2saldian-Me3 has two chiral centers, as shown in equation (13) below. Therefore, the products obtained here include cis-(S,R), trans-(R,R), trans-(S,S), and trans-(R,S) isomers.

[0071] The obtained H2saldian-Me3 1 1H NMR and 13 The 13C NMR spectrum was measured, and the results are shown below.

[0072] 1 H NMR (δ / ppm vs. TMS, CDCl3) 7.14 (td, 2 H, Ph-H), 6.94 (dd, 2 H, Ph-H), 6.80 (dd, 2 H, Ph-H), 6.75 (td, 2 H, Ph-H), 3.66 (s, 4 H, Ph-CH2-N), 2.59 (m, 8 H, N-CH2CH2-N), 2.26 (s, 6 H, N-CH3), 2.23 (s, 3 H, N-CH3).

[0073] 13 C NMR (δ / ppm vs. TMS, CDCl3) 157.93, 128.78, 128.72, 122.31, 118.98, 116.22, 60.88, 55.31, 54.39, 42.30, 42.00.

[0074] [ka]

[0075] (Synthesis Example 5) "Synthesis of H2saldian(p-OMe) (compound (Ic) represented by formula (2) above)" To a tetrahydrofuran solution (10 mL), 2-hydroxy-5-methoxybenzaldehyde (0.430 mL, 3.45 mmol, Tokyo Chemical Industry Co., Ltd.) and diethylenetriamine (0.187 mL, 1.725 mmol, Tokyo Chemical Industry Co., Ltd.) were added and refluxed for 1 hour. Then, under ice cooling, 6 equivalents of sodium triacetoxyborohydride were added and stirred overnight at room temperature. Distilled water (5 mL) and 25 wt% sodium hydroxide aqueous solution (5 mL) were added to adjust the pH to around 11-12. After concentration under reduced pressure using a rotary evaporator, the mixture was extracted with dichloromethane. The separated organic phase was dried over magnesium sulfate, and the filtrate was concentrated under reduced pressure using a rotary evaporator to obtain yellow oily H2saldian (p-OMe) (90% yield).

[0076] The obtained H2saldian(p-OMe) 1 The 1H NMR spectrum was measured, and the results are shown below.

[0077] 1 H NMR (δ / ppm vs. TMS, CDCl3) 6.80 (d, 2 H, Ph-H), 6.72 (dd, 2 H,Ph-H), 6.60 (d, 2 H, Ph-H), 3.99 (s, 4 H, Ph-CH2-N), 3.71 (s, 6 H, -OCH3), 2.80 (s, 8 H, N-CH2-CH2-N).

[0078] (Synthesis Example 6) "Synthesis of H2saldian(p-CF3) (compound represented by formula (2) above (If))" 5-Trifluoromethylsalicyaldehyde (0.62 mmol, Tokyo Chemical Industry Co., Ltd.) and diethylenetriamine (0.31 mmol, Tokyo Chemical Industry Co., Ltd.) were dissolved in methanol (5 mL) and refluxed for 2 hours. After cooling to room temperature, sodium borohydride was added in small amounts and stirred overnight. Distilled water (5 mL) was added to the reaction solution, and after concentration under reduced pressure using a rotary evaporator, it was extracted with dichloromethane. The separated organic phase was dried over sodium sulfate, and the filtrate was concentrated under reduced pressure using a rotary evaporator to obtain pale yellow solid H2saldian (p-CF3) (57% yield).

[0079] The obtained H2saldian(p-CF3) 1 1H NMR and 19 The 1F NMR spectrum was measured, and the results are shown below.

[0080] 1 H NMR (δ / ppm vs. TMS, CDCl3) 7.43 (s, 2 H, Ph-H), 7.38 (d, 2 H, Ph-H), 6.80 (d, 2 H, Ph-H), 3.86 (s, 4 H, Ph-CH2-N), 2.63 (m, 8 H, N-CH2-CH2-N).

[0081] 19 F NMR (δ / ppm, CDCl3) -59 (s, CF3).

[0082] (Synthesis Example 7) "Synthesis of H2saldian(-(CH2)2-NH) resin (a polymer having the structure of a compound or ion represented by general formula (1))" Under an argon atmosphere, chloromethyl polystyrene resin (2.08 g, manufactured by Tokyo Chemical Industry Co., Ltd., degree of divinylbenzene crosslinking: 1%, chloro content: 2.0 mmol / g, particle size: 100-200 mesh) and tris(aminoethyl)amine (3.04 g, 20.8 mmol, manufactured by Tokyo Chemical Industry Co., Ltd.) were mixed in N,N-dimethylformamide (15 mL, manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.), and the suspension was stirred at 65°C for 12 hours. After cooling to room temperature, the solid components were filtered off by suction filtration, washed with 2-propanol, and dried under reduced pressure. The obtained solid (2.60 g) was suspended in methanol (30 mL), salicylaldehyde (2.34 g, 19.2 mmol, manufactured by Tokyo Chemical Industry Co., Ltd.) and acetic acid (2 mL, 8.74 mmol, manufactured by Kanto Chemical Co., Ltd.) were added, and the mixture was stirred at room temperature for 4 hours. The solid components were filtered off by suction filtration, washed with methanol and tetrahydrofuran, and dried under reduced pressure. The obtained solid was suspended in fresh methanol (30 mL), and borane-2-picoline complex (1.03 g, 9.61 mmol) and acetic acid (2 mL) were added. The mixture was stirred at room temperature for 5 hours. The solid, filtered off by suction filtration, was washed with methanol and dried under reduced pressure. The obtained solid was suspended in an aqueous hydrochloric acid solution at pH 2, then filtered by suction filtration, and the solid on the filter paper was washed 10 times with distilled water (30 mL). After further washing with an aqueous solution at pH 6 (30 mL) prepared with sodium hydroxide, it was washed 5 times with distilled water (30 mL). The obtained solid was dried under reduced pressure to obtain a pale yellow resin powder, H2saldian(-(CH2)2-NH) resin (2.16 g).

[0083] The infrared absorption spectrum of the obtained H2saldian (-(CH2)2-NH) resin was measured. The results are shown in Figure 4. In comparison with the infrared absorption spectra of the chloromethyl polystyrene resin and H2saldian (compound Ia) used as the substrate, the 1252 cm⁻¹ spectrum originating from H2saldian was observed. ―1 and 1588cm -1 Since the peak was also observed in H2saldian(-(CH2)2-NH) resin, it was determined that it is a polymer represented by the following formula (14). The introduction rate of the H2saldian structure in H2saldian(-(CH2)2-NH) resin is 1.2 mmol / g.

[0084] [ka]

[0085] (Synthesis Example 8) "Synthesis of H2saldian resin (a polymer having the structure of a compound or ion represented by general formula (1))" Under an argon atmosphere, chloromethyl polystyrene resin (4.76 g, manufactured by Tokyo Chemical Industry Co., Ltd., degree of divinylbenzene crosslinking: 1%, chloro content: 2.0 mmol / g, particle size: 100-200 mesh) and H2saldian (3.04 g, 9.64 mmol) obtained by the same procedure as in Synthesis Example 2 were mixed in N,N-dimethylformamide (30 mL, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and this suspension was stirred at 90°C for 12 hours. After cooling to room temperature, the solid components were filtered off by suction filtration and washed with 2-propanol and distilled water. The obtained solid was suspended in an aqueous solution (30 mL) with pH 9 containing 0.5 M Na2CO3 and 0.5 M NaHCO3 and stirred at room temperature for 2 hours. The solid components were filtered off by suction filtration and the filtrate was repeatedly washed with distilled water until it became neutral. Further washing with ethanol and subsequent vacuum drying of the resulting solid yielded a pale yellow resin powder of H2saldian resin (5.96 g).

[0086] The infrared absorption spectrum of the obtained H2saldian resin was measured. The results are shown in Figure 4. In comparison with the infrared absorption spectra of the chloromethyl polystyrene resin and H2saldian (compound Ia) used as the substrate, the 1252 cm⁻¹ spectrum originating from H2saldian was observed. ―1 and 1588cm -1 The presence of the peak in H2saldian resin indicates that it is a polymer represented by the following formula (15). Since H2saldian has two types of nitrogen atoms that can bond to polymers, H2saldian can be introduced in two forms as shown in formula (15). The introduction rate of the H2saldian structure in H2saldian resin is 1.2 mmol / g.

[0087] [ka]

[0088] (Example 1) "Synthesis of uranium complexes (UO2 (saldian))" H2saldian (0.138 g, 0.438 mmol) obtained in Synthesis Example 2 was dissolved in 2-propanol (3 mL) and then heated on a hot stirrer. While stirring well, UO2(NO3)2·6H2O (0.219 g, 0.438 mmol) dissolved in 2-propanol (500 μ L) was added dropwise to this reaction solution. After cooling the mixture to -18°C, the orange microcrystals were collected by filtration and washed with cold diisopropyl ether to obtain UO2(saldian) (0.212 g, 0.364 mmol, 83% yield).

[0089] Using the above method for measuring the complex stability constant, the common logarithm (logβ) of the complex stability constant of the uranium complex (UO2(saldian)) was obtained. 11 ) was measured. As a result, logβ 11 The result was 27.5. This is shown in Table 1.

[0090] (Example 2) Simulated seawater conditions (0.5M NaCl+2.3mM HCO3 - / CO3 2- The ultraviolet-visible light absorption spectrum of a solution of compound (Ia) obtained in synthesis example 2 and UO2(NO3)2·6H2O was measured at pH 8.0. 2+ The concentration is 0-0.15 mM (UO2 2+ Solutions were prepared by gradually adding UO2(NO3)2·6H2O so that the concentration ratio of Ia was 0 to 1.5. The ultraviolet-visible absorption spectra of these solutions are shown in Figure 1.

[0091] (Example 3) "UO2 2+ -saldian 2- "Systemic complex distribution diagram" The logβ of UO2 (saldian) mentioned above 11 Based on this, an equilibrium calculation program was used to calculate various UO2 values ​​in the pH range of 0 to 14. 2+ The mole fraction of the complex was determined. The results are shown in Figure 2. However, [X] in Figure 2 TOT This represents the total concentration of the chemical species represented by X. Composition and concentration of aqueous solutions: 0.5M NaCl + 2.3mM HCO3 - / CO3 2- 0.10mM saldian 2- 14.00nM UO2 2+ Measurement temperature: room temperature

[0092] (Example 4) "Synthesis of uranium complexes (UO2 (acetdian))" The compound (IIa)(H2acetdian) obtained in Synthesis Example 3 was reacted with UO2(NO3)2·6H2O in ethanol. As a result, orange microcrystalline powder of UO2(acetdian) was obtained in 83% yield.

[0093] Using the above method for measuring the stability constant of the complex, logβ of the uranium complex (UO2(acetdian)) 11 The following was measured: logβ 11 The result was 27.9. This is shown in Table 1.

[0094] (Example 5) "Synthesis of uranium complex (UO2(saldian-Me3))" H2saldian-Me3 (0.087 g, 0.24 mmol) obtained in Synthesis Example 4 was dissolved in ethanol (3 mL) and subsequently heated with a hot stirrer. While stirring well, UO2(NO3)2·6H2O (0.118 g, 0.23 mmol) dissolved in ethanol (400 μL) and triethylamine (34 μL, 0.24 mmol) were added dropwise to this hot solution. After stirring at 85°C for 30 minutes, the mixture was cooled to -18°C. The orange microcrystals were filtered off and washed with cold ethanol and methyl tert-butyl ether to obtain UO2(saldian-Me3) (0.147 g, 0.24 mmol, 99% yield). Plate-like crystals of UO2(saldian-Me3) were obtained by recrystallization from high-temperature DMSO.

[0095] Using the above method for measuring the stability constant of the complex, logβ of the uranium complex (UO2(saldian‐Me3)) 11 The following was measured: logβ 11 The result was 26.2.

[0096] (Example 6) "Synthesis of uranium complex (UO2(saldian(p-OMe)))" H2saldian(p-OMe) (0.086 g, 0.23 mmol) obtained in Synthesis Example 5 was dissolved in ethanol (3 mL) and subsequently heated with a hot stirrer. While stirring well, UO2(NO3)2·6H2O (0.118 g, 0.23 mmol) dissolved in ethanol (400 μL) and triethylamine (34 μL, 0.24 mmol) were added dropwise to this hot solution. After stirring at 85°C for 30 minutes, the mixture was cooled to -18°C. The orange microcrystals were filtered off and washed with cold ethanol and methyl tert-butyl ether to obtain yellow-orange crystalline powder UO2(saldian(p-OMe) (0.13 g, 0.20 mmol, 88% yield).

[0097] Using the above method for measuring the stability constant of the complex, the logβ of the uranium complex (UO2(saldian(p-OMe))) was determined. 11 The following was measured: logβ 11The result was 24.81. This is shown in Table 2.

[0098] (Example 7) "Synthesis of uranium complex (UO2(saldian(p-CF3)))" H2saldian(p-CF3) (0.10 g, 0.23 mmol) obtained in Synthesis Example 6 was dissolved in ethanol (3 mL) and subsequently heated with a hot stirrer. While stirring well, UO2(NO3)2·6H2O (0.118 g, 0.23 mmol) dissolved in ethanol (400 μL) and triethylamine (34 μL, 0.24 mmol) were added dropwise to this hot solution. After stirring at 85°C for 30 minutes, the mixture was cooled to -18°C. The orange microcrystals were filtered off and washed with cold ethanol and methyl tert-butyl ether to obtain yellow-orange crystalline powder UO2(saldian(p-CF3) (0.081 g, 0.18 mmol, 78% yield).

[0099] Using the above method for measuring the stability constant of the complex, the logβ of the uranium complex (UO2(saldian(p-CF3)) was determined. 11 The following was measured: logβ 11 The result was 23.5. This is shown in Table 2.

[0100] (Example 8) "Quantum chemical calculations show that R in general formula (1) 3 and R 8 (p-substitution), R 2 and R 7 Investigation of the effects of (m-substituted) substituents. In compound (1) represented by the above general formula (1), R 3 and R 8 (p-substitution), R 2 and R 7 When the (m-substitution) is -CH3, -OMe, -Cl, -CF3, or -NO2, the deprotonation energy ΔE shown in equation (16) below was calculated by quantum chemical calculation. A plot of the predicted values ​​of ΔE for each functional group was obtained. The results are shown in Figure 3. The quantum chemical calculations were performed under the following conditions. Calculation code: Gaussian16 / B01, Method: B3LYP hybrid density functional theory, Basis set: 6-311G(d), Solvent effect: SCRF=WATER.

[0101] [ka]

[0102] The meaning of each symbol in Figure 3 is as follows: ΔE: Binding energy of the hydrogen ion to the phenoxy ion group (strength of electron donation → magnitude of the complex stability constant) σ p : Para position (R 3 ,R 8 ) Electron-withdrawing properties of the functional group introduced σ m : Meta position (R 2 ,R 7 ) Electron-withdrawing properties of the functional group introduced p-CH3:R 3 and R 8 =-CH3, other R 1 ~R 13 =H p-OMe:R 3 and R 8 =-OMe, other R 1 ~R 13 =H p-Cl:R 3 and R 8 = -Cl, other R 1 ~R 13 =H p-CF3:R 3 and R 8 =-CF3, other R 1 ~R 13 =H p-NO2:R 3 and R 8 =-NO2, other R 1 ~R 13 =H m-CH3:R 2 and R 7 =-CH3, other R 1 ~R 13 =H m-OMe:R2 and R 7 =-OMe, other R 1 ~R 13 =H m-Cl:R 2 and R 7 = -Cl, other R 1 ~R 13 =H m-CF3:R 2 and R 7 =-CF3, other R 1 ~R 13 =H m-NO2:R 2 and R 7 =-NO2, other R 1 ~R 13 =H

[0103] (Comparative Example 1) "Synthesis of metal complexes other than uranium" The compound (Ia)(H2saldian) obtained in Synthesis Example 2 and the alkali metal ion (Na + , K + ), alkaline earth metals (Mg 2+ Ca 2+ ,Sr 2+ Ba 2+ ), Zr 4+ MoO4 2- When mixed with the salt, no complex formation was observed.

[0104] (Comparative Example 2) "Synthesis of metal complexes other than uranium" The compound (IIa)(H2acetdian) obtained in Synthesis Example 3 and the alkali metal ion (Na + , K + ), alkaline earth metals (Mg 2+ Ca 2+ ,Sr 2+ Ba 2+ ), Al 3+ , Zr 4+ MoO4 2- When mixed with the salt, no complex formation was observed.

[0105] (Comparative Example 3) "Synthesis of metal complexes other than uranium" Compound (Ia)(H2saldian) obtained in Synthesis Example 2 and various metal (M) ions: Al 3+ VO2 + Ni 2+ Cu 2+ Zn 2+ , Cd 2+ The mixture was then obtained to obtain a metal complex. Using the above method for measuring the stability constant of the complex, the logβ of each complex was determined. 11 The separation coefficients of uranium for each of these metal ions were also measured. The results are shown in Table 1.

[0106] (Comparative Example 4) "Synthesis of metal complexes other than uranium" Compound (IIa)(H2acetdian) obtained in Synthesis Example 3 and various metal (M) ions:VO2 + Ni 2+ Cu 2+ Zn 2+ , Cd 2+ The mixture was then obtained to obtain a metal complex. Using the above method for measuring the stability constant of the complex, the logβ of each complex was determined. 11 The separation coefficients of uranium for each of these metal ions were also measured. The results are shown in Table 1.

[0107] (Comparative Example 5) "Synthesis of metal complexes other than uranium" The compound (Ic)(H2saldian(p-OMe)) obtained in Synthesis Example 5 and various metal (M) ions: Ni 2+ Cu 2+ Zn 2+ , Cd 2+ The mixture was then obtained to obtain a metal complex. Using the above method for measuring the stability constant of the complex, the logβ of each complex was determined. 11 The separation coefficients of uranium for each of these metal ions were also measured. The results are shown in Table 2.

[0108] (Comparative Example 6) "Synthesis of metal complexes other than uranium" The compound obtained in Synthesis Example 3 (If)(H2saldian(p-CF3)) and various metal (M) ions: Ni 2+Cu 2+ Zn 2+ , Cd 2+ The mixture was then obtained to obtain a metal complex. Using the above method for measuring the stability constant of the complex, the logβ of each complex was determined. 11 The separation coefficients of uranium for each of these metal ions were also measured. The results are shown in Table 2.

[0109] [Table 1]

[0110] [Table 2]

[0111] (Comparative Example 7) "Conventional ligands for collecting uranium from seawater and uranium (UO2 2+ ) complex formation and complex stability constant logβ 11 " <Synthesis of Ligand Compounds> Using a method similar to that described in Non-Patent Document 2, compounds of conventional ligands for collecting uranium from seawater were synthesized: benzamidoxime, acetamidoxime, 1,10-phenanthroline-2,9-dicarboxylic acid, glutarimidodioxime, and 2,6-bis[hydroxy(methyl)amino]-4-morpholino-1,3,5-triazine.

[0112] <Synthesis of complexes> Using the same method as in Example 1, the ligand obtained in the above synthesis and uranium (UO2) 2+ A complex was synthesized with ).

[0113] <Common logarithm of the complex stability constant (logβ) 11 ) measurement> The stability constant logβ of the complex obtained above was determined by the same method as in Example 1. 11 The following measurements were taken. The results are as follows: Benzamidoxime: 12.4 Acetamidoxime: 13.6 1,10-Phenanthroline-2,9-dicarboxylic acid: 16.5 Glutarimidodioxime: 17.8 2,6-Bis[hydroxy(methyl)amino]-4-morpholino-1,3,5-triazine:17.47

[0114] (Consideration) In all of Examples 1 to 7, UO2 2+ Complex formation with UO2 has been confirmed, and this is because the compound represented by general formula (1) has a planar pentatene coordination. 2+ This is thought to be because it has a structure that fits well with the characteristic properties of each UO2. 2+ logβ of the complex 11 In addition, the logβ obtained in Examples 1 and 4 11 The value is more than 10 orders of magnitude larger than that of the conventional uranium capture ligand for seawater shown in Comparative Example 7, demonstrating that a very stable uranium complex can be formed even under seawater conditions. This makes it possible to capture uranium from seawater with high efficiency. Furthermore, as summarized in Table 1, the uranium separation coefficient for other contaminating ions is Al 3+ VO2 + For all other parameters, the values ​​range from 100,000 to 100 billion times, making it extremely superior in terms of selectivity. 3+ Since it does not form complexes with H2acetdian, using it allows UO2 2+ Selective separation of VO2 becomes possible. + Regarding this as well, an improvement in the separation coefficient was observed by replacing H2saldian with H2acetdian. From these results, it can be expected that further improvements in uranium collection performance and separation performance can be expected by applying appropriate molecular design, such as introducing functional groups as shown in general formula (1). In addition, from the results shown in Example 8, Figure 3 and Table 2, the R of the compound represented by general formula (1) 1 ~R 13 By introducing electron-withdrawing or electron-donating functional groups, selectivity for other contaminating ions is maintained while UO2 2+It was revealed that it is possible to control the complex stability constant. Furthermore, it was confirmed that polymers with an H2saldian structure can be synthesized in synthesis example 7, synthesis example 8, and Figure 4, and these can be applied as seawater uranium adsorbents. [Industrial applicability]

[0115] According to the present invention, it is possible to provide a ligand for collecting uranium from seawater with high efficiency even at a pH of around 8, which is typical for seawater, a method for collecting uranium from seawater using the same, and a method for producing uranium raw materials.

Claims

1. Uranium in seawater, One or more selected from the group consisting of a compound represented by the following general formula (1), an ion derived from the compound, and a polymer having the structure of the compound or the ion, A method for collecting uranium from seawater, which involves selectively forming a metal complex to collect the uranium, The complex stability constant (logβ) of the aforementioned metal complex in seawater. １１ A method for collecting uranium from seawater, wherein the ratio is 21 or higher. 【Chemistry 1】 (In general formula (1), R １ ~R １３ These terms independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a dialkylamino group composed of an alkyl group having 1 to 5 carbon atoms, a nitro group, a perfluoroalkyl group composed of 1 to 5 carbon atoms, and a halogen group.

2. The method for collecting uranium from seawater according to Claim 1, wherein in the general formula (1) above, R1 to R10 each independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a dialkylamino group composed of an alkyl group having 1 to 5 carbon atoms, and a halogen group; and R11 to R13 each independently represent a hydrogen atom and an alkyl group having 1 to 5 carbon atoms.

3. The method for collecting uranium from seawater according to claim 1 or 2, wherein in the general formula (1) above, R1 to R10 each independently represent a hydrogen atom or a methyl group, and R11 to R13 represent a hydrogen atom.

4. The method for collecting seawater uranium according to any one of claims 1 to 3, wherein the uranium exists as UO22+.

5. A collection step of collecting uranium from seawater using the seawater uranium collection method described in any one of claims 1 to 4, A method for producing uranium raw materials, comprising: a release step in which the uranium collected in the collection step is released by adjusting the pH.

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