Preparation method of seawater uranium efficient extraction hydrogel

Abstract

This invention discloses a method for preparing a high-efficiency uranium extraction hydrogel from seawater, comprising the following steps: Step I: Hydroxylamine hydrochloride is completely dissolved in dimethylformamide (DMF), then Na2CO3 and NaOH are added and stirred rapidly; Step II: Polyacrylonitrile (PAN) is added to the above mixture for reaction, and the resulting reaction mixture is filtered twice through a 0.22 μm filter membrane to obtain poly(aminoamine)oxime (PAO); Step III: A precursor solution containing Zn(NO3)2·6H2O and Cu(NO3)2·3H2O is added in batches to an aqueous solution of Na2CO3, and NaOH solution is gradually added dropwise to adjust the pH; Step IV: The suspension is continuously stirred in a water bath, filtered, thoroughly washed with acetone, and dried to obtain Zn-Cu layered hydroxide (ZnCu-LDH); Step V: The PAO solution and ZnCu-LDH are mixed in a certain proportion to rapidly form a hydrogel. Practical verification shows that the PAO-ZnCu-LDH hydrogel has an adsorption capacity of up to 282 mg / g for uranium. This invention features a simple, quick, and reliable preparation process with high adsorption performance, making it a promising candidate for application in the field of ion selective recovery.

Description

Technical Field

[0001] This invention relates to the field of uranium adsorption technology and discloses a method for preparing a highly efficient uranium extraction hydrogel from seawater. Background Technology

[0002] Nuclear energy, with its significant advantages of high energy density, stable operation, and near-zero carbon emissions, is widely regarded as one of the most promising alternatives to traditional fossil fuels. However, the large-scale application of nuclear energy heavily relies on uranium resources, a key nuclear fuel. The ocean contains approximately 4.5 billion tons of uranium, nearly a thousand times the amount found on land. If a technologically feasible and economically viable breakthrough can be achieved in extracting uranium from seawater, it will provide a near-unlimited fuel supply for the nuclear energy industry. Uranium in seawater primarily exists as the extremely stable uranyl tricarbonate anion ([UO2(CO3)3]). 4- Uranium exists in the form of uranium ions, at extremely low concentrations (approximately 3.3 μg / L), and is accompanied by a large number of competing ions, whose concentrations are several orders of magnitude higher than those of uranium ions. Therefore, developing adsorbent materials capable of selectively and efficiently capturing trace amounts of uranium from such a complex matrix is ​​crucial for the practical application of seawater uranium extraction technology.

[0003] Over the past few decades, various adsorbent materials have been developed, including inorganic adsorbents, porous organic polymers, and biomass materials. Among them, PAO-based materials are widely recognized as one of the most promising materials for uranium extraction from seawater due to the excellent selective coordination ability of the amylopyrime group (-C(NOH)NH2) for uranium ions. However, traditional PAO-based adsorbents (such as fibers and microspheres) still have some inherent bottlenecks, such as slow adsorption kinetics and poor mechanical stability.

[0004] To overcome the aforementioned challenges, compositing PAO with LDH to construct a porous, hydrophilic three-dimensional network structure—a hydrogel—is considered an effective strategy. The high water content and interconnected channels of the hydrogel significantly promote ion transport, thereby greatly enhancing adsorption kinetics. LDH constructed from Zn and Cu (ZnCu-LDH) exhibits unique advantages: Zn... 2+ The introduction of Cu helps to form a stable laminated structure. 2+ Not only can it serve as a structural unit, but its incompletely filled d orbitals can also synergistically interact with amine oxime groups, further enhancing its coordination ability for uranyl ions. Based on the above analysis, this invention prepares a novel high-performance hydrogel adsorbent for uranium extraction from seawater using an ultrafast crosslinking strategy of PAO and ZnCu-LDH. Summary of the Invention

[0005] In view of the above shortcomings, in order to efficiently adsorb uranium from seawater and significantly enhance selectivity in actual seawater, the purpose of this invention is to prepare a hydrogel containing numerous adsorption sites, which has excellent adsorption performance for uranium and can be rapidly prepared on a large scale.

[0006] To achieve the above-mentioned technical effects, the present invention employs the following technical means:

[0007] This invention first discloses a method for preparing a hydrogel for high-efficiency uranium extraction from seawater, comprising the following steps:

[0008] (1) Hydroxylamine hydrochloride was completely dissolved in DMF (dimethylformamide), and then Na2CO3 and NaOH were added. After magnetic stirring, mixed substance I was obtained.

[0009] (2) Add PAN (polyacrylonitrile) to mixture I and heat to react. After the reaction is complete, filter it twice to obtain PAO solution;

[0010] (3) Add the precursor solution containing Zn(NO3)2·6H2O and Cu(NO3)2·3H2O to the Na2CO3 aqueous solution in batches, and gradually add NaOH solution to adjust the pH to obtain a suspension.

[0011] (4) After continuously stirring the suspension in a constant temperature water bath, filter it, wash it thoroughly with acetone, and dry it to obtain ZnCu-LDH (Zn-Cu layered hydroxide).

[0012] (5) Mix PAO solution and ZnCu-LDH in a certain proportion to obtain PAO-ZnCu-LDH hydrogel.

[0013] Further, in step (1), the mass of hydroxylamine hydrochloride is 9.28 g, the volume of DMF is 100 mL, the mass of Na2CO3 is 6.45 g, and the mass of NaOH is 1.62 g.

[0014] Further, the mass of PAN in step (2) is 7.14 g; the heating reaction conditions are: heating at 65°C for 24 h; and the pore size of the filter membrane used for filtration is 0.22 μm.

[0015] Further, in step (3), the concentrations of Zn(NO3)2·6H2O and Cu(NO3)2·3H2O are 0.2 M, and the concentration of the Na2CO3 aqueous solution is 0.4 M.

[0016] Furthermore, in step (3), the concentration of the NaOH solution is 4 M, and the pH of the mixed salt solution is maintained at 10.0 ± 0.2.

[0017] Further, the constant temperature water bath temperature in step (4) is 45°C; the continuous stirring conditions are: 300 rpm and stirring for 24 h.

[0018] Further, the filter membrane used in step (4) has a pore size of 0.22 μm; the drying conditions are: temperature 60℃, drying for 24 h.

[0019] Further, the mass ratio of PAO solution and ZnCu-LDH in step (5) is 20:1.

[0020] The present invention also discloses a high-efficiency seawater uranium extraction hydrogel prepared according to any of the above preparation methods.

[0021] The present invention also discloses the application of the above-mentioned seawater uranium high-efficiency extraction hydrogel in ion recovery treatment.

[0022] Compared with existing technologies, the present invention has the following advantages:

[0023] (1) When the hydrogel prepared by the present invention is used for seawater uranium extraction, it has a rapid synthesis performance that is difficult to achieve with other physical and chemical cross-linking processes (the synthesis rate of traditional physical and chemical cross-linking hydrogel preparation processes is relatively slow, ranging from tens of minutes to several hours), and has good application prospects in the field of seawater uranium extraction.

[0024] (2) When the hydrogel prepared by the present invention is used for uranium extraction from seawater, it has more reliable adsorption performance and has significant advantages in resisting shock loads and changes in environmental conditions (see Examples 2 and 3 for details).

[0025] (3) When the hydrogel prepared by the present invention is used for uranium extraction from seawater, it exhibits a certain degree of sustainability (see Example 1 for details), which can reduce the replacement of adsorbents, energy consumption and cost. Attached Figure Description

[0026] Figure 1 The graph shows the adsorption performance of uranium on hydrogels formed with different proportions of PAO-LDH.

[0027] Figure 2 The adsorption capacity of uranium for hydrogels formed with different proportions of PAO-LDH is shown in the diagram.

[0028] Figure 3 The figure shows the effect of different initial uranium concentrations on the adsorption performance of PAO-LDH hydrogel on uranium.

[0029] Figure 4 The figure shows the effect of different pH conditions on the adsorption performance of PAO-LDH hydrogel on uranium. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] A method for preparing a hydrogel for efficient uranium extraction from seawater includes the following steps:

[0033] (1) Dissolve 9.28 g of hydroxylamine hydrochloride completely in 100 mL of DMF (dimethylformamide), then add 6.45 g of Na2CO3 and 1.62 g of NaOH, and stir magnetically to obtain mixture I;

[0034] (2) 7.14 g PAN (polyacrylonitrile) was added to mixture I and heated at 65°C for 24 h. After the reaction was completed, the mixture was filtered twice using a filter membrane with a pore size of 0.22 μm to obtain PAO solution.

[0035] (3) Add the precursor solutions containing 0.2 M Zn(NO3)2·6H2O and 0.2 M Cu(NO3)2·3H2O in batches to a 0.4 M Na2CO3 aqueous solution, and gradually add 0.4 M NaOH solution to adjust the pH to ≈10 to obtain a suspension;

[0036] (4) The suspension was continuously stirred in a constant temperature water bath at 45℃ for 24 h at a stirring speed of 300 rpm. After filtration through a 0.22 μm filter membrane, it was thoroughly washed with acetone and dried at 60℃ for 24 h to obtain ZnCu-LDH (Zn-Cu layered hydroxide).

[0037] (5) Mix PAO solution and ZnCu-LDH at a mass ratio of 20:1 to obtain PAO-ZnCu-LDH hydrogel.

[0038] Experimental Example 1

[0039] (1) PAO-LDH hydrogels with PAO-LDH mass ratios of 5:1, 10:1, 20:1 and 40:1 were prepared.

[0040] (2) Prepare a uranium-containing solution of 20 mg / L in ultrapure water with a volume of 5 L. Stir continuously with a magnetic stirrer at a speed of 150 rpm and adjust the pH of the solution to 6.0 with 0.1 M NaOH.

[0041] (3) A certain mass of hydrogel was placed in a uranium-containing solution for adsorption test. Samples were taken at different times, and the adsorption time was 48 h.

[0042] (4) The uranium concentration in the solution after adsorption by different hydrogels was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES), with three parallel determinations. See details in [link to results]. Figure 1 ,according to Figure 1 The results showed that the hydrogel with a PAO-LDH mass ratio of 20:1 exhibited the best adsorption performance for uranium.

[0043] (5) BET tests were conducted on PAO-LDH hydrogels with mass ratios of 20:1 and 40:1, which confirmed the high adsorption capacity and certain sustainability of PAO-LDH (20:1).

[0044] The amount of uranium adsorbed was calculated using Formula 1.

[0045] (1)

[0046] In the formula, Q is the adsorption capacity of the hydrogel (mg / g); C0 and C t The values ​​represent the uranium concentration (mg / L) before and after adsorption, respectively; V is the total volume of the solution; and W is the dry weight of the hydrogel.

[0047] Experimental Example 2

[0048] (1) PAO-LDH hydrogels with a PAO-LDH content ratio of 20:1 were prepared.

[0049] (2) Prepare uranium-containing solutions with different uranium concentrations (5, 10, 20, 40 mg / L) in ultrapure water with a volume of 5 L. Stir continuously with a magnetic stirrer at 150 rpm and adjust the pH of the solution to 6.0 with 0.1 M NaOH.

[0050] (3) A certain mass of hydrogel was placed in a uranium-containing solution for adsorption test. Samples were taken at different times, and the adsorption time was 48 h.

[0051] (4) The uranium concentration in the solution after PAO-LDH hydrogel adsorption was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) in triplicate. See details below. Figure 2 ,according to Figure 2 The results show that the hydrogel has high adsorption performance at different uranium concentrations and is capable of resisting shock loads.

[0052] Experimental Example 3

[0053] (1) PAO-LDH hydrogels with a PAO-LDH content ratio of 20:1 were prepared.

[0054] (2) Prepare a uranium-containing solution of 20 mg / L in ultrapure water with a volume of 5 L. Stir continuously with a magnetic stirrer at a speed of 150 rpm and adjust the pH of the solution to 6.0 with 0.1 M NaOH.

[0055] (3) PAO-LDH hydrogels of different concentrations (5, 10, 20, 40 mg / L) were placed in uranium-containing solutions for adsorption tests. Samples were taken at different times, and the adsorption time was 48 h.

[0056] (4) The uranium concentration in the solution after PAO-LDH hydrogel adsorption was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) in triplicate. See details below. Figure 3 ,according to Figure 3 The results show that the hydrogel has high adsorption performance at different PAO-LDH hydrogel concentrations and has the ability to resist shock loads.

[0057] Test Example 4

[0058] (1) PAO-LDH hydrogels with a PAO-LDH content ratio of 20:1 were prepared.

[0059] (2) Prepare a uranium-containing solution of 20 mg / L in ultrapure water with a volume of 5L. Stir continuously with a magnetic stirrer at a speed of 150 rpm and adjust the pH of the solution with 0.1 M NaOH or 0.1 M HCl.

[0060] (3) A certain mass of hydrogel was placed into a uranium-containing solution for adsorption test. Samples were taken at different times, and the adsorption time was 48 h.

[0061] (4) The uranium concentration after adsorption by PAO-LDH hydrogel in solutions of different pH values ​​was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) in triplicate. See details below. Figure 4 ,according to Figure 4 The results show that the hydrogel has high adsorption performance under different pH conditions and has a significant advantage in resisting changes in environmental conditions.

[0062] The above description is only a specific embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A method for preparing a high-efficiency uranium extraction hydrogel from seawater, comprising the following steps: (1) Dissolve hydroxylamine hydrochloride completely in DMF, then add Na2CO3 and NaOH, and stir magnetically to obtain mixture I; (2) Add PAN to mixture I and heat to react. After the reaction is complete, filter it twice to obtain PAO solution. (3) Add the precursor solution containing Zn(NO3)2·6H2O and Cu(NO3)2·3H2O to the Na2CO3 aqueous solution in batches, and gradually add NaOH solution to adjust the pH to obtain a suspension. (4) After continuously stirring the suspension in a constant temperature water bath, filter it, wash it thoroughly with acetone, and dry it to obtain ZnCu-LDH; (5) Mix PAO solution and ZnCu-LDH in a certain proportion to obtain PAO-ZnCu-LDH hydrogel.

2. The preparation method according to claim 1, characterized in that: The mass of hydroxylamine hydrochloride in step (1) is 9.28 g, and the volume of DMF is 100 mL; The mass of Na2CO3 is 6.45 g, and the mass of NaOH is 1.62 g.

3. The preparation method according to claim 1, characterized in that: The mass of PAN in step (2) is 7.14 g; The heating reaction conditions were: heating at 65°C for 24 hours; The filter membrane used for filtration has a pore size of 0.22 μm.

4. The preparation method according to claim 1, characterized in that: In step (3), the concentrations of Zn(NO3)2·6H2O and Cu(NO3)2·3H2O are 0.2 M, and the concentration of Na2CO3 aqueous solution is 0.4 M.

5. The preparation method according to claim 1, characterized in that: In step (3), the concentration of the NaOH solution is 4 M, and the pH of the mixed salt solution is maintained at 10.0 ± 0.

2.

6. The preparation method according to claim 1, characterized in that: The constant temperature water bath temperature in step (4) is 45℃; The continuous stirring conditions are: 300 rpm, stirring for 24 h.

7. The preparation method according to claim 1, characterized in that: The filter membrane used in step (4) has a pore size of 0.22 μm; The drying conditions are: temperature 60℃, drying time 24 h.

8. The preparation method according to claim 1, characterized in that: The mass ratio of PAO solution to ZnCu-LDH in step (5) is 20:

1.

9. A high-efficiency uranium extraction hydrogel from seawater prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the seawater uranium high-efficiency extraction hydrogel according to claim 9 in ion recovery treatment.

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