A seawater uranium extraction adsorbent, a preparation method and application thereof

Abstract

This invention discloses a seawater uranium extraction adsorbent, its preparation method, and its application, belonging to the field of adsorbent technology. The adsorbent uses modified one-dimensional rod-shaped mesoporous magnesium oxide as a support, with the active component, a methylamine oxime, dispersed within the support; the loading of the active component is 15%-20% of the support mass; the modified one-dimensional rod-shaped mesoporous magnesium oxide is obtained by modifying γ-aminopropyltriethoxysilane. The adsorbent provided by this invention exhibits stable structure and excellent selective adsorption, maintaining excellent adsorption selectivity and structural stability even under higher uranium concentrations and salinity conditions.

Description

Technical Field

[0001] This invention belongs to the field of adsorbent technology, and particularly relates to a seawater uranium extraction adsorbent, its preparation method, and its application. Background Technology

[0002] Clean energy has become one of the major challenges facing the world. The sea contains about 4.5 billion tons of uranium, which serves as a "reserve" to ensure the long-term supply of nuclear fuel.

[0003] Adsorption is the most widely studied and promising method for uranium extraction from seawater. In this method, inorganic matrices loaded with amylopectin (RC(NH2) =NOH, AO) functional groups are the main adsorbents. The inorganic matrix provides structural and mass transfer support, high mechanical strength, and high specific surface area, while the amylopectin groups provide targeted binding sites. Together, they achieve high capacity, high selectivity, fast kinetics, and stable adsorption performance. For example, patent CN102211017B discloses a amylopectin-based uranium extraction adsorbent. This patent introduces cyano groups into inorganic materials through a hydrolysis-condensation reaction, followed by amination to prepare amylopectin-functionalized organic-inorganic hybrid mesoporous material. The prepared adsorbent exhibits high selectivity and good hydrophilicity. In recent years, scholars both domestically and internationally have conducted a series of studies on this system, achieving certain results. However, the research and application of this system still face unavoidable core challenges. First, existing research focuses on optimizing organic functional groups, neglecting the key role of the composition, structure, and morphology of inorganic carriers in mechanical strength. Under the long-term impact of ocean waves, the carrier skeleton is prone to collapse, which restricts the improvement of adsorbent performance. Second, most existing research is concentrated in ideal laboratory solution systems, with limited performance studies in real seawater systems. This makes it difficult to achieve the leap from laboratory to practical engineering applications, thus making it difficult to adapt to the design and application needs of multiple scenarios. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a seawater uranium extraction adsorbent, its preparation method, and its applications. The seawater uranium extraction adsorbent provided by this invention exhibits structural stability and excellent selective adsorption, maintaining superior adsorption selectivity and structural stability even under higher uranium concentrations and salinity conditions.

[0005] To solve the aforementioned technical problem, the technical solution adopted by the present invention is as follows: This invention provides a seawater uranium extraction adsorbent, wherein the adsorbent uses modified one-dimensional rod-shaped mesoporous magnesium oxide as a support, and the active component, a methylamine oxime, is dispersed in the support; the loading of the active component is 15%-20% of the support mass; The modified one-dimensional rod-shaped mesoporous magnesium oxide was obtained by modification with γ-aminopropyltriethoxysilane.

[0006] Preferably, the modified one-dimensional rod-shaped mesoporous magnesium oxide is prepared by the following steps: 1) Mix magnesium chloride solution with sodium polystyrene sulfonate, add sodium carbonate solution to the resulting mixed solution under stirring, and then stir, let stand for aging, filter, dry and calcine in sequence to obtain one-dimensional rod-shaped mesoporous magnesium oxide. 2) Mix the one-dimensional rod-shaped mesoporous magnesium oxide, anhydrous ethanol, and deionized water, add γ-aminopropyltriethoxysilane to the resulting dispersion, adjust the pH of the system to 4.5-5.0, and carry out the reaction to obtain modified one-dimensional rod-shaped mesoporous magnesium oxide.

[0007] Preferably, in step 1), the molar ratio of magnesium chloride to sodium polystyrene sulfonate is 2.5-3:0.1; and the molar ratio of magnesium chloride to sodium carbonate is 1:1.

[0008] Preferably, the static aging time in step 1) is 10-16 hours; the drying temperature is 70-75°C; and the calcination temperature is 490-520°C for 2.5-4 hours.

[0009] Preferably, the mass ratio of the one-dimensional rod-shaped mesoporous magnesium oxide to γ-aminopropyltriethoxysilane in step 2) is 1:0.08-0.12; the reaction temperature in step 2) is 55-60℃ and the reaction time is 3-5h.

[0010] This invention provides a method for preparing the seawater uranium extraction adsorbent according to any one of the above claims, comprising the following steps: (1) The modified one-dimensional rod-shaped mesoporous magnesium oxide was mixed with N,N-dimethylformamide to obtain a suspension; (2) Add ammonia oxime to the suspension and react at 40-50℃ for 1.5-2.5h, then raise the temperature to 65-75℃ and react for 20-28h. After the reaction is completed, centrifuge and dry to obtain seawater uranium extraction adsorbent.

[0011] Preferably, the geminal oxime is prepared by the following method: a. Mix acrylonitrile and N,N-dimethylformamide, add hydroxylamine hydrochloride, sodium carbonate and sodium hydroxide to the resulting mixture, stir and react at 45-55℃ for 1.5-2.5h, then raise the temperature to 65-75℃ and react for 20-28h to obtain the reaction system; b. Add deionized water dropwise to the reaction system, and a white precipitate will form. Filter, wash and dry the precipitate in sequence to obtain a methylamine oxime powder.

[0012] Preferably, the ratio of acrylonitrile, N,N-dimethylformamide, hydroxylamine hydrochloride, sodium carbonate, and sodium hydroxide is 11-13 mmol: 18-22 mL: 11-13 mmol: 8-10 mmol: 5-7 mmol.

[0013] This invention provides the application of the seawater uranium extraction adsorbent described in any one of the above-mentioned methods in seawater uranium extraction, wherein the volume-to-mass ratio of seawater to adsorbent is (900-2100L):10g.

[0014] Preferably, the seawater is concentrated seawater after seawater desalination or concentrated seawater discharged from the power plant cooling water circulation system.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The seawater uranium extraction adsorbent provided by this invention utilizes the mesoporous confinement effect of one-dimensional rod-shaped mesoporous magnesium oxide to anchor the amylopectin active component within nanoscale channels. On one hand, the high specific surface area and regular channels of the mesopores achieve high dispersion and full exposure of the active component, shortening the mass transfer path of uranyl ions and increasing the contact probability, thereby significantly improving adsorption capacity and adsorption rate. On the other hand, the mesoporous channels, through size sieving, physically block interfering ions of mismatched size in seawater, synergistically enhancing the precise identification capability of uranium with the chemoselectivity of the amylopectin groups. Furthermore, the one-dimensional rod-shaped morphology endows the support with excellent resistance to water erosion. The physical confinement of the amylopectin by the mesoporous channels, combined with the chemical anchoring of the silane-modified layer, provides dual protection against the detachment of the active component during long-term use. Simultaneously, the magnesium oxide support exhibits excellent salt resistance and chemical inertness, maintaining structural stability even in high-salinity media such as concentrated seawater, thus ensuring the service life of the adsorbent.

[0016] The seawater uranium extraction adsorbent provided in this application uses one-dimensional rod-shaped mesoporous magnesium oxide modified with γ-aminopropyltriethoxysilane as a support and a methylamine oxime as the active component. The support has high strength, preventing the adsorbent from collapsing under the influence of seawater waves, effectively resisting wave impact. Furthermore, the high specific surface area, porosity, and high number of active sites of the mesoporous magnesium oxide allow for sufficient loading of the methylamine oxime, improving the adsorption rate and capacity. Simultaneously, the modification of the one-dimensional rod-shaped mesoporous magnesium oxide with γ-aminopropyltriethoxysilane enhances the interaction between the methylamine oxime and the support, ensuring stable adsorption of the methylamine oxime on the support and preventing detachment, thus improving the stability and service life of the adsorbent.

[0017] The adsorbent provided by this invention is suitable for uranium extraction scenarios such as seawater, concentrated seawater, and brine in salt lakes. It can maintain excellent adsorption selectivity and structural stability even under higher uranium concentration and salinity conditions, significantly improving the economic efficiency and resource utilization efficiency of uranium extraction. It is of great value for promoting the large-scale engineering application of seawater uranium extraction.

[0018] Furthermore, this invention uses concentrated seawater obtained from seawater desalination or concentrated seawater discharged from a power plant cooling water circulation system. Before entering the adsorption process, this seawater undergoes pretreatment such as flocculation, scale inhibition, and biocidal activity, significantly reducing suspended solids, microorganisms, and scale-forming ions. This not only helps reduce adsorbent contamination and clogging, extending its service life, but also ensures effective contact between the active sites of the oxime and uranyl ions, thereby improving the adsorption capacity and selectivity of uranium. Attached Figure Description

[0019] Figure 1 This is an electron microscope image of the one-dimensional rod-shaped mesoporous magnesium oxide prepared in Example 1; Figure 2 This is an electron microscope image of the one-dimensional rod-shaped mesoporous magnesium oxide prepared in Example 2; Figure 3 This is an electron microscope image of the one-dimensional rod-shaped mesoporous magnesium oxide prepared in Example 3; Figure 4 The image shows an electron microscope image of the mesoporous magnesium oxide prepared in Comparative Example 1. Figure 5 This is an electron microscope image of the mesoporous magnesium oxide prepared in Comparative Example 3. Detailed Implementation

[0020] The technical solutions in specific embodiments of the present invention will be described in detail and completely below. Obviously, the described embodiments are only some specific implementations of the overall technical solution of the present invention, and not all implementations. Based on the overall concept of the present invention, all other embodiments obtained by those skilled in the art fall within the protection scope of the present invention.

[0021] This invention provides a seawater uranium extraction adsorbent, wherein the adsorbent uses modified one-dimensional rod-shaped mesoporous magnesium oxide as a carrier, and the active component, a methylamine oxime, is dispersed in the carrier; the loading of the active component is 15%-20% of the carrier mass; the modified one-dimensional rod-shaped mesoporous magnesium oxide is obtained by modifying γ-aminopropyltriethoxysilane.

[0022] Magnesium oxide (MgO) is widely available, environmentally friendly, and chemically stable, and its surface contains a large number of uncoordinated Mg atoms. 2+ Mg 2+ (Lewis acid) and O 2-(Lewis base) active sites can effectively capture uranyl ions through ion exchange and surface coordination. However, the microstructure of conventional MgO is mostly irregular particles, which has the following defects: (1) The irregular morphology leads to severe particle aggregation, low specific surface area and porosity, and a large number of active sites are buried inside the particles and cannot participate in the adsorption reaction, resulting in insufficient utilization of active sites and low adsorption capacity; (2) The aggregate structure is loose, the interparticle binding force is weak, the mechanical strength is insufficient, and it is easy to break and be lost under dynamic water flow conditions, affecting the service life of the adsorbent. In order to address the above defects, our research group designed a one-dimensional rod-shaped mesoporous magnesium oxide (MgO) support. Its rod-shaped morphology gives the material excellent resistance to water flow impact, and the mesoporous structure provides a high specific surface area and abundant mass transfer channels, which fully exposes the active sites, thereby significantly improving the adsorption rate and adsorption capacity. Based on this, γ-aminopropyltriethoxysilane (KH550) was used to modify the surface of one-dimensional rod-shaped mesoporous MgO, introducing amino anchors to enhance the binding force between the amylopyridine groups and the support, effectively inhibiting the shedding of amylopyridine groups during long-term immersion in seawater, and improving the cycle stability and service life of the adsorbent.

[0023] In this invention, the modified one-dimensional rod-shaped mesoporous magnesium oxide is preferably prepared by the following steps: 1) Mix magnesium chloride solution with sodium polystyrene sulfonate, add sodium carbonate solution to the resulting mixed solution under stirring, and then stir, let stand for aging, filter, dry and calcine in sequence to obtain one-dimensional rod-shaped mesoporous magnesium oxide. 2) Mix the one-dimensional rod-shaped mesoporous magnesium oxide, anhydrous ethanol, and deionized water, add γ-aminopropyltriethoxysilane to the resulting dispersion, adjust the pH of the system to 4.5-5.0, and carry out the reaction to obtain modified one-dimensional rod-shaped mesoporous magnesium oxide.

[0024] In this invention, the molar ratio of magnesium chloride to sodium polystyrene sulfonate in step 1) is preferably 2.5-3:0.1; the molar ratio of magnesium chloride to sodium carbonate is preferably 1:1. In this invention, sodium polystyrene sulfonate (PSS) is used as a structure-directing agent to prepare one-dimensional rod-shaped mesoporous magnesium oxide. In this invention, the aging time in step 1) is preferably 10-16 hours. In this invention, after filtration, washing with deionized water is preferred to improve product purity. In this invention, the drying temperature in step 1) is preferably 70-75°C, and the drying time is preferably 3.5-4.5 hours. In this invention, the calcination temperature is preferably 490-520°C, and the calcination time is preferably 2.5-4 hours.

[0025] After obtaining one-dimensional rod-shaped mesoporous magnesium oxide, the present invention mixes the one-dimensional rod-shaped mesoporous magnesium oxide, anhydrous ethanol, and deionized water, adds γ-aminopropyltriethoxysilane to the resulting dispersion, adjusts the pH of the system to 4.5-5.0, and proceeds with the reaction to obtain modified one-dimensional rod-shaped mesoporous magnesium oxide. In the present invention, the preferred mass-to-volume ratio of the one-dimensional rod-shaped mesoporous magnesium oxide, anhydrous ethanol, and deionized water is 1 g: 35-45 mL: 8-12 mL. In the present invention, ultrasonic dispersion is preferably used after mixing. In the present invention, the preferred mass ratio of the one-dimensional rod-shaped mesoporous magnesium oxide to γ-aminopropyltriethoxysilane is 1:0.08-0.12. In the present invention, the preferred reaction temperature in step 2) is 55-60°C, and the preferred reaction time is 3-5 h. In this invention, adjusting the pH of the system to 4.5-5.0 for the reaction can promote the hydrolysis and condensation of γ-aminopropyltriethoxysilane (KH550), allowing it to be uniformly grafted onto the magnesium oxide surface, avoiding excessive hydrolysis that leads to self-polymerization, ensuring a dense and stable modified layer, and significantly enhancing the binding force between the support and the amylopectin.

[0026] This invention provides a method for preparing the seawater uranium extraction adsorbent according to any one of the above claims, comprising the following steps: (1) The modified one-dimensional rod-shaped mesoporous magnesium oxide was mixed with N,N-dimethylformamide to obtain a suspension; (2) Add ammonia oxime to the suspension and react at 40-50℃ for 1.5-2.5h, then raise the temperature to 65-75℃ and react for 20-28h. After the reaction is completed, centrifuge and dry to obtain seawater uranium extraction adsorbent.

[0027] In this invention, the preferred mass-to-volume ratio of the modified one-dimensional rod-shaped mesoporous magnesium oxide to N,N-dimethylformamide (DMF) is 1.0 g: 45-50 mL. In this invention, ultrasonic dispersion is preferably used after mixing to obtain a uniform suspension. In this invention, the reaction is first carried out at 40-50°C for 1.5-2.5 h to fully disperse the amylopectin and initially anchor it on the support surface; then the temperature is raised to 65-75°C for 20-28 h to promote deep loading and chemical bonding of the amylopectin, improve loading uniformity and structural stability, and avoid agglomeration and uneven loading caused by direct high-temperature reaction. In this invention, the preferred drying temperature is 50-60°C, and the preferred drying time is 20-28 h.

[0028] In this invention, the amine oxime is preferably prepared by the following steps: a. Mix acrylonitrile and N,N-dimethylformamide, add hydroxylamine hydrochloride, sodium carbonate and sodium hydroxide to the resulting mixture, stir and react at 45-55℃ for 1.5-2.5h, then raise the temperature to 65-75℃ and react for 20-28h to obtain the reaction system; b. Add deionized water dropwise to the reaction system, and a white precipitate will form. Filter, wash and dry the precipitate in sequence to obtain a methylamine oxime powder.

[0029] In this invention, the preferred ratio of acrylonitrile, N,N-dimethylformamide, hydroxylamine hydrochloride, sodium carbonate, and sodium hydroxide is 11-13 mmol: 18-22 mL: 11-13 mmol: 8-10 mmol: 5-7 mmol, more preferably 12 mmol: 20 mL: 12 mmol: 9 mmol: 6 mmol. In this invention, the preferred drying temperature is 50°C, and the preferred drying time is 12 hours.

[0030] This invention provides the application of the seawater uranium extraction adsorbent described in any one of the above-mentioned methods in seawater uranium extraction, wherein the volume-to-mass ratio of seawater to adsorbent is (900-2100L):10g. In this invention, the seawater is preferably concentrated seawater from seawater desalination or concentrated seawater discharged from a power plant cooling water circulation system. The concentrated seawater remaining after seawater desalination and the concentrated seawater discharged from the power plant cooling water circulation system undergo purification treatments such as flocculation, scale inhibition, and biocidal activity. Bacteria and other pollutants in the concentrated seawater are essentially removed, resulting in clean water. Furthermore, due to the concentration of the seawater, the uranium ion concentration is correspondingly increased by 2-3 times. This invention, using the aforementioned seawater, not only effectively improves the antibacterial properties of the adsorbent but also enhances the adsorption effect, effectively solving the problems of low uranium concentration and adsorbent contamination in seawater uranium extraction.

[0031] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0032] Example 1 1) Preparation of one-dimensional rod-shaped mesoporous magnesium oxide 568.4 g of magnesium chloride hexahydrate was dissolved in deionized water to prepare a magnesium chloride solution with a concentration of 0.43 mol / L and a total volume of 6.5 L. Separately, 296.8 g of anhydrous sodium carbonate was dissolved in deionized water to prepare a sodium carbonate solution with a concentration of 0.43 mol / L and a total volume of 6.5 L. 19.5 g of sodium polystyrene sulfonate (PSS), a structure-directing agent, was added to the magnesium chloride solution and stirred until completely dissolved to obtain a mixed solution. Under vigorous stirring, an equal volume of sodium carbonate solution was added to this mixed solution, and the reaction was continued for 30 min. The mixture was then allowed to stand for 16 h. The reaction product was filtered and washed with deionized water, then dried at 70 °C for 4 h to obtain a precursor. The precursor was placed in a muffle furnace and calcined at 500 °C for 3 h to obtain a specific surface area of ​​161 m². 2 One-dimensional rod-shaped mesoporous magnesium oxide with a pore size of 7.5 nm per g is produced. This one-dimensional rod-shaped mesoporous magnesium oxide exhibits a regular microstructure and uniform aspect ratio. Electron micrographs are shown below. Figure 1As shown.

[0033] 2) Preparation of modified one-dimensional rod-shaped mesoporous magnesium oxide Take 1.0 g of the prepared one-dimensional rod-shaped mesoporous magnesium oxide and add it to a mixed solution of 40 mL anhydrous ethanol and 10 mL deionized water. Disperse the mixture by sonication for 20 min. After sonication, add 0.1 g of KH550 (γ-aminopropyltriethoxysilane) to adjust the pH of the system to 4.5. Stir the mixture in a water bath at 60 °C for 4 h. After the reaction is complete, centrifuge and then dry the mixture under vacuum at 55 °C for 24 h to obtain the modified one-dimensional rod-shaped mesoporous magnesium oxide.

[0034] 3) Preparation of amine oxime Take 0.64 g (12 mmol) of acrylonitrile and add it to 20 mL of N,N-dimethylformamide (DMF). Stir to dissolve. Add 0.86 g (12 mmol) of hydroxylamine hydrochloride, 0.95 g (9 mmol) of sodium carbonate, and 0.24 g (6 mmol) of sodium hydroxide. Stir in a water bath at 45 °C for 2 h, then raise the temperature to 65 °C and react for 24 h. After the reaction is complete, add deionized water dropwise to the system. A white precipitate precipitates out. Filter, wash, and dry under vacuum at 50 °C for 12 h to obtain amylopyroxime powder.

[0035] 4) Preparation of adsorbent Take 1.0 g of the modified one-dimensional rod-shaped mesoporous magnesium oxide prepared in step 2), add it to 50 mL of LDMF, and ultrasonically disperse it for 30 min to obtain a uniform suspension; add 0.18 g of the amylopectin prepared in step 3) (the mass ratio of modified one-dimensional rod-shaped mesoporous magnesium oxide to amylopectin is 5.6:1) to the suspension, stir it in a water bath at 45 °C for 2 h, then react it at a constant temperature of 65 °C for 24 h, centrifuge it, and vacuum dry it at 55 °C for 24 h to obtain the adsorbent.

[0036] Example 2 1) Preparation of one-dimensional rod-shaped mesoporous magnesium oxide 568.4 g of magnesium chloride hexahydrate was dissolved in deionized water to prepare a magnesium chloride solution with a concentration of 0.43 mol / L and a total volume of 6.5 L. Separately, 296.8 g of anhydrous sodium carbonate was dissolved in deionized water to prepare a sodium carbonate solution with a concentration of 0.43 mol / L and a total volume of 6.5 L. 19 g of sodium polystyrene sulfonate (PSS), a structure-directing agent, was added to the magnesium chloride solution and stirred until completely dissolved to obtain a mixed solution. Under vigorous stirring, an equal volume of sodium carbonate solution was added to this mixed solution, and the reaction was continued for 30 min, followed by standing and aging for 10 h. The reaction product was filtered and washed with deionized water, then dried at 75 °C for 4 h to obtain a precursor. The precursor was placed in a muffle furnace and calcined at 520 °C for 2.5 h to obtain a product with a specific surface area of ​​150 m². 2One-dimensional rod-shaped mesoporous magnesium oxide with a pore size of 8.2 nm per g was produced. This one-dimensional rod-shaped mesoporous magnesium oxide exhibits a regular microstructure and uniform aspect ratio. Electron micrographs are shown below. Figure 2 As shown.

[0037] 2) Preparation of modified one-dimensional rod-shaped mesoporous magnesium oxide Take 1.0 g of the one-dimensional rod-shaped mesoporous magnesium oxide prepared above, add it to a mixed solution of 40 mL anhydrous ethanol and 10 mL deionized water, and sonicate for 20 min. After sonication, add 0.12 g KH550 (γ-aminopropyltriethoxysilane), adjust the pH of the system to 5.0, stir the reaction in a water bath at 55 °C for 5 h, centrifuge after the reaction, and vacuum dry at 55 °C for 24 h to obtain modified one-dimensional rod-shaped mesoporous magnesium oxide.

[0038] 3) Preparation of amine oxime Take 0.64 g (12 mmol) of acrylonitrile and add it to 20 mL of N,N-dimethylformamide (DMF) and stir to dissolve. Add 0.86 g (12 mmol) of hydroxylamine hydrochloride, 0.95 g (9 mmol) of sodium carbonate and 0.24 g (6 mmol) of sodium hydroxide. First, stir in a water bath at 50 °C for 2.5 h, then raise the temperature to 70 °C and react for 20 h. After the reaction is completed, add deionized water dropwise to the system, and a white precipitate will precipitate. Filter, wash and dry under vacuum at 50 °C for 12 h to obtain amylopyroxime powder.

[0039] 4) Preparation of adsorbent Take 1.0 g of the modified one-dimensional rod-shaped mesoporous magnesium oxide prepared in step 2), add it to 50 mL of LDMF, and ultrasonically disperse it for 30 min to obtain a uniform suspension; add 0.15 g of the amylopectin prepared in step 3) (the mass ratio of modified one-dimensional rod-shaped mesoporous magnesium oxide to amylopectin is 6.7:1) to the suspension, stir it in a water bath at 40 °C for 2.5 h, then react it at a constant temperature of 75 °C for 20 h, centrifuge it, and vacuum dry it at 55 °C for 24 h to obtain the adsorbent.

[0040] Example 3 1) Preparation of one-dimensional rod-shaped mesoporous magnesium oxide 568.4 g of magnesium chloride hexahydrate was dissolved in deionized water to prepare a magnesium chloride solution with a concentration of 0.43 mol / L and a total volume of 6.5 L. Separately, 296.8 g of anhydrous sodium carbonate was dissolved in deionized water to prepare a sodium carbonate solution with a concentration of 0.43 mol / L and a total volume of 6.5 L. 21.8 g of sodium polystyrene sulfonate (PSS), a structure-directing agent, was added to the magnesium chloride solution and stirred until completely dissolved to obtain a mixed solution. Under vigorous stirring, an equal volume of sodium carbonate solution was added to this mixed solution, and the reaction was continued for 40 min, followed by standing and aging for 16 h. The reaction product was filtered and washed with deionized water, then dried at 70 °C for 4 h to obtain a precursor. The precursor was placed in a muffle furnace and calcined at 490 °C for 4 h to obtain a precursor with a specific surface area of ​​170 m². 2 One-dimensional rod-shaped mesoporous magnesium oxide with a pore size of 6.4 nm per g was produced. This one-dimensional rod-shaped mesoporous magnesium oxide exhibits a regular microstructure and uniform aspect ratio. Electron micrographs are shown below. Figure 3 As shown.

[0041] 2) Preparation of modified one-dimensional rod-shaped mesoporous magnesium oxide Take 1.0 g of the one-dimensional rod-shaped mesoporous magnesium oxide prepared above, add it to a mixed solution of 40 mL anhydrous ethanol and 10 mL deionized water, and sonicate for 20 min. After sonication, add 0.08 g KH550 (γ-aminopropyltriethoxysilane) to adjust the pH of the system to 4.5. Stir the reaction in a water bath at 60 °C for 4 h. After the reaction is completed, centrifuge and dry under vacuum at 55 °C for 24 h to obtain modified one-dimensional rod-shaped mesoporous magnesium oxide.

[0042] 3) Preparation of amine oxime Take 0.64 g (12 mmol) of acrylonitrile and add it to 20 mL of N,N-dimethylformamide (DMF) and stir to dissolve. Add 0.86 g (12 mmol) of hydroxylamine hydrochloride, 0.95 g (9 mmol) of sodium carbonate and 0.24 g (6 mmol) of sodium hydroxide. First, stir in a water bath at 55 °C for 1.5 h, then raise the temperature to 75 °C and react for 28 h. After the reaction is completed, add deionized water dropwise to the system, and a white precipitate will precipitate. Filter, wash and dry under vacuum at 50 °C for 12 h to obtain amylopyroxime powder.

[0043] 4) Preparation of adsorbent Take 1.0 g of the modified one-dimensional rod-shaped mesoporous magnesium oxide prepared in step 2), add it to 50 mL of LDMF, and ultrasonically disperse it for 30 min to obtain a uniform suspension; add 0.2 g of the amylopectin prepared in step 3) (the mass ratio of modified one-dimensional rod-shaped mesoporous magnesium oxide to amylopectin is 5:1) to the suspension, stir it in a water bath at 45 °C for 2 h, then react it at a constant temperature of 70 °C for 28 h, centrifuge it, and vacuum dry it at 55 °C for 24 h to obtain the adsorbent.

[0044] Comparative Example 1 The difference from Example 1 is that no structure-directing agent PSS was added during the preparation of magnesium oxide. The specific operation is as follows: 1) Preparation of magnesium oxide 568.4 g of magnesium chloride hexahydrate was dissolved in deionized water to prepare a 0.43 mol / L, 6.5 L solution. Separately, 296.8 g of anhydrous sodium carbonate was prepared into a 0.43 mol / L, 6.5 L solution. The sodium carbonate solution was added dropwise to the magnesium chloride solution under vigorous stirring for 30 min. The mixture was allowed to stand for 16 h, filtered and washed, dried at 70 °C for 4 h, and calcined at 500 °C for 3 h to obtain one-dimensional rod-shaped mesoporous magnesium oxide. The electron micrograph of this one-dimensional rod-shaped mesoporous magnesium oxide is shown below. Figure 4 As shown. By Figure 4 It can be seen that the prepared one-dimensional rod-shaped mesoporous magnesium oxide not only has fewer pores, but also has an irregular shape.

[0045] 2) Preparation of amine oxime Take 0.64 g (12 mmol) of acrylonitrile and add it to 20 mL of N,N-dimethylformamide (DMF). Stir to dissolve. Add 0.86 g (12 mmol) of hydroxylamine hydrochloride, 0.95 g (9 mmol) of sodium carbonate, and 0.24 g (6 mmol) of sodium hydroxide. Stir in a water bath at 45 °C for 2 h, then raise the temperature to 65 °C and react for 24 h. After the reaction is complete, add deionized water dropwise to the system. A white precipitate precipitates out. Filter, wash, and dry under vacuum at 50 °C for 12 h to obtain amylopyroxime powder.

[0046] 3) Preparation of adsorbent Take 1.0 g of the mesoporous magnesium oxide prepared in step 1) and add it to 50 mL of LDMF. Disperse it by ultrasonication for 30 min to obtain a uniform suspension. Add 0.18 g of the amylopectin prepared in step 2) (the mass ratio of mesoporous magnesium oxide to amylopectin is 5.6:1) to the suspension. Stir in a water bath at 45 °C for 2 h, then react at a constant temperature of 65 °C for 24 h. Separate by centrifugation and vacuum dry at 55 °C for 24 h to obtain the adsorbent.

[0047] Comparative Example 2 The difference from Example 1 is that the one-dimensional rod-shaped mesoporous magnesium oxide was not modified. The specific operation is as follows: 1) Preparation of one-dimensional rod-shaped mesoporous magnesium oxide 568.4 g of magnesium chloride hexahydrate was dissolved in deionized water to prepare a magnesium chloride solution with a concentration of 0.43 mol / L and a total volume of 6.5 L. Separately, 296.8 g of anhydrous sodium carbonate was dissolved in deionized water to prepare a sodium carbonate solution with a concentration of 0.43 mol / L and a total volume of 6.5 L. 19.5 g of sodium polystyrene sulfonate (PSS), a structure-directing agent, was added to the magnesium chloride solution and stirred until completely dissolved to obtain a mixed solution. Under vigorous stirring, an equal volume of sodium carbonate solution was added to this mixed solution, and the reaction was continued for 30 min. The mixture was then allowed to stand for 16 h. The reaction product was filtered and washed with deionized water, then dried at 70 °C for 4 h to obtain a precursor. The precursor was placed in a muffle furnace and calcined at 500 °C for 3 h to obtain a specific surface area of ​​161 m². 2 / g, one-dimensional rod-shaped mesoporous magnesium oxide product with a pore size of 7.5nm.

[0048] 2) Preparation of amine oxime Take 0.64 g (12 mmol) of acrylonitrile and add it to 20 mL of N,N-dimethylformamide (DMF). Stir to dissolve. Add 0.86 g (12 mmol) of hydroxylamine hydrochloride, 0.95 g (9 mmol) of sodium carbonate, and 0.24 g (6 mmol) of sodium hydroxide. Stir in a water bath at 45 °C for 2 h, then raise the temperature to 65 °C and react for 24 h. After the reaction is complete, add deionized water dropwise to the system. A white precipitate precipitates out. Filter, wash, and dry under vacuum at 50 °C for 12 h to obtain amylopyroxime powder.

[0049] 3) Preparation of adsorbent Take 1.0 g of the one-dimensional rod-shaped mesoporous magnesium oxide prepared in step 1), add it to 50 mL of LDMF, and ultrasonically disperse it for 30 min to obtain a uniform suspension; add 0.18 g of the amylopectin prepared in step 2) (the mass ratio of one-dimensional rod-shaped mesoporous magnesium oxide to amylopectin is 5.6:1) to the suspension, stir it in a water bath at 45 °C for 2 h, then react it at a constant temperature of 65 °C for 24 h, centrifuge it, and vacuum dry it at 55 °C for 24 h to obtain the adsorbent.

[0050] Comparative Example 3 The difference from Example 1 is that non-rod-shaped ordinary mesoporous magnesium oxide is used as the support; all other operations are exactly the same as in Example 1. The mesoporous magnesium oxide is prepared using the following steps: 568.4 g of magnesium chloride hexahydrate was dissolved in deionized water to prepare a magnesium chloride solution with a concentration of 0.43 mol / L and a total volume of 6.5 L. Separately, 296.8 g of anhydrous sodium carbonate was dissolved in deionized water to prepare a sodium carbonate solution with a concentration of 0.43 mol / L and a total volume of 6.5 L. 19.5 g of sodium polystyrene sulfonate (PSS), a structure-directing agent, was added to the magnesium chloride solution and stirred until completely dissolved to obtain a mixed solution. Under vigorous stirring, an equal volume of sodium carbonate solution was added to this mixed solution, and the reaction was continued for 10 min. The reaction product was filtered and washed with deionized water, then dried at 70 °C for 4 h to obtain a precursor. The precursor was placed in a muffle furnace and calcined at 500 °C for 3 h to obtain a specific surface area of ​​138 m². 2 / g, a plate-shaped mesoporous magnesium oxide with a pore size of 7.9nm, is shown in the electron microscope image below. Figure 5 As shown.

[0051] Comparative Example 4 The difference from Example 1 is that in step 4), when preparing the adsorbent, 0.18g of amine oxime was added to the suspension and the mixture was directly reacted at a constant temperature of 65°C for 26 hours. Other operations were the same as in Example 1, with the specific operation of step 4) as follows: Take 1.0 g of the modified one-dimensional rod-shaped mesoporous magnesium oxide prepared in step 2), add it to 50 mL of LDMF, and ultrasonically disperse it for 30 min to obtain a uniform suspension; add 0.18 g of the amylopectin prepared in step 3) (the mass ratio of modified one-dimensional rod-shaped mesoporous magnesium oxide to amylopectin is 5.6:1) to the suspension, react at a constant temperature of 65 °C for 26 h, centrifuge, and vacuum dry at 55 °C for 24 h to obtain the adsorbent.

[0052] Example 4 The specific procedure for determining the amount of uranium adsorbed is as follows: 1) Natural seawater was filtered using a cellulose acetate membrane with a pore size of 0.22 micrometers to remove particulate matter, colloids, and organic matter. The filtered seawater was then analyzed by ICP-MS to determine uranyl ions (UO2²). + The concentration was 0.0032 mg / L.

[0053] 2) Spiking treatment: Accurately transfer 500 mL of the filtered seawater into a 1000 mL beaker. Add uranyl nitrate aqueous solution to this seawater, stir thoroughly, and determine and calibrate using inductively coupled plasma mass spectrometry (ICP-MS) to achieve a uranyl ion spike concentration of 10 mg / L. Therefore, the actual total concentration of uranyl ions in the initial solution of the adsorption experiment is the sum of the background concentration and the spike concentration, approximately 10.0032 mg / L. 3) Static adsorption experiment: The five spiked seawater samples were transferred to 1000 mL Erlenmeyer flasks, and 5 mg (0.005 g) of the adsorbent prepared in Examples 1-3 and Comparative Examples 1-4 was accurately added to each sample. The Erlenmeyer flasks were placed in a constant temperature water bath shaker, with the temperature set at 25 °C and the shaking rate at 180 r / min, to carry out the static adsorption reaction for 1 hour, ensuring that the adsorbent and the spiked seawater were in full contact.

[0054] 4) Sample processing and detection: After the adsorption reaction was completed, the mixture in the conical flask was centrifuged at 8000 r / min for 10 min. The supernatant was carefully aspirated and filtered through a 0.22 μm filter membrane to remove minor impurities. The remaining UO2 in the supernatant was determined by ICP-MS. 2+ equilibrium concentration (C) e The measurements were performed in parallel three times, and the average value was taken. 5) Performance Calculation: Based on the difference in uranium ion concentration before and after adsorption, calculate the adsorption capacity (Q) and adsorption rate (R) of the adsorbent for uranium. The calculation formulas are as follows: Q=(C0-C e )×V / m R=[(C0-C e ) / C0]×100% Where Q is the adsorption capacity (mg / g) and C0 is the UO2 in the spiked seawater. 2+ Initial concentration (10 mg / L), C e To determine the UO2 in the supernatant after adsorption equilibrium 2+ Concentration (mg / L), V is the volume of seawater spiked (0.5L), and m is the mass of the adsorbent (0.005g). Experimental results: The adsorption capacities of Examples 1-3 and Comparative Examples 1-4 were determined to be 245 mg-U / g, 237 mg-U / g, 278 mg-U / g, 45 mg-U / g, 135 mg-U / g, 141 mg-U / g and 201 mg-U / g, respectively.

[0055] Example 5 The difference from Example 4 is that the adsorbent is concentrated seawater (uranyl ions (UO2)) after seawater desalination treatment. 2+ The concentration of uranyl ions (UO2²⁻) in this concentrated seawater is 0.0055 mg / L. + The concentration of uranyl nitrate was determined to be 0.0055 mg / L by ICP-MS. Based on this, following the spiking method of Example 4, an aqueous solution of uranyl nitrate was added to the concentrated seawater to bring the spiking concentration of uranyl ions to 10 mg / L. Therefore, the actual total concentration of uranyl ions in the initial solution of the adsorption experiment was the sum of the background concentration and the spiking concentration, approximately 10.0055 mg / L. All other operations were exactly the same as in Example 4.

[0056] The adsorption capacities measured in Examples 1-3 and Comparative Examples 1-4 were 254 mg-U / g, 244 mg-U / g, 286 mg-U / g, 47 mg-U / g, 142 mg-U / g, 149 mg-U / g, and 210 mg-U / g, respectively. This indicates that the adsorbent of this invention maintains excellent adsorption performance when using desalinated concentrated seawater as raw material. Furthermore, due to the purification pretreatment of the concentrated seawater through flocculation, scale inhibition, and biocidal processes, the suspended solids, microorganisms, and scale-forming ions in the water are significantly reduced, alleviating the pollution and clogging of the adsorbent and allowing the amylopectin active sites to exert their adsorption effect more fully. Therefore, the adsorption capacity is further improved at the same spiking concentration.

[0057] Example 6 Mechanical wear resistance test Test method: Weigh the dried adsorbent to constant weight and pass it through a 200-mesh sieve. Take 0.5g of the adsorbent on the sieve, weigh it using an electronic balance (accurate to 0.0001g) and record it as m0. Then place the sample in 50mL of seawater (composition same as seawater in Example 4), put it in a constant temperature water bath and control the temperature at 25±1℃. Turn on the magnetic stirrer and adjust the speed to 400rpm, and stir continuously for 24h to simulate fluid disturbance under actual working conditions. After stirring, place the mixture in a centrifuge and centrifuge at 3000rpm for 10min, and collect the precipitate. The adsorbent was then placed in a vacuum drying oven and dried at 60°C until constant weight. The mass was accurately weighed and recorded as m1. The dried adsorbent was then sieved through a 200-mesh standard sieve. The adsorbent on the sieve was collected and accurately weighed and recorded as m2. The mechanical wear resistance was evaluated by calculating the mass loss rate and breakage rate. The mass loss rate W = (m0-m1) / m0 × 100%, and the breakage rate R = (m1-m2) / m1 × 100%. When the breakage rate ≤ 3% and the mass loss rate ≤ 2%, it indicates that the adsorbent has excellent mechanical wear resistance and can meet the requirements of actual working conditions.

[0058] The adsorbents of each embodiment and comparative example were tested using the above-described test methods. The test results were as follows: the breakage rates of embodiments 1, 2, and 3 and comparative examples 1-4 were 1.05%, 1.10%, 1.04%, 4.05%, 3.34%, 5.58%, and 1.20%, respectively; and the mass loss rates were 0.94%, 0.93%, 0.91%, 2.9%, 2.32%, 6.22%, and 1.12%, respectively.

[0059] As can be seen from the data in Examples 4-6, the adsorbents provided in the embodiments of the present invention exhibit superior adsorption effects and mechanical properties compared to the comparative examples. Specifically, in Comparative Example 1, the absence of the structure-directing agent PSS resulted in fewer pores and poor regularity of the rod-shaped structure in the prepared mesoporous magnesium oxide, leading to significantly lower adsorption performance and mechanical strength compared to Example 1. Comparative Example 2, lacking modification of the support with γ-aminopropyltriethoxysilane, lacked chemical anchoring between the amylopectin and the support, resulting in weaker interactions and easy detachment of the active component. Consequently, the stability and breakage rate of the adsorbent were inferior to those in the examples. Comparative Example 3 used ordinary disc-shaped mesoporous magnesium oxide, whose mechanical strength and erosion resistance were significantly inferior to the one-dimensional rod-shaped structure of the present invention, resulting in a substantial reduction in adsorption effect. Furthermore, Comparative Example 4 employed a one-step high-temperature direct reaction, which, compared to the segmented gradient heating method of the examples, easily caused amylopectin aggregation and uneven loading. The segmented heating strategy of the present invention effectively improved the uniformity of loading and structural stability, thereby achieving simultaneous improvement in adsorption performance and mechanical properties.

[0060] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A seawater uranium extraction adsorbent, characterized in that, The adsorbent uses modified one-dimensional rod-shaped mesoporous magnesium oxide as a support, and the active component, a amine oxime, is dispersed in the support; the loading of the active component is 15%-20% of the support mass; The modified one-dimensional rod-shaped mesoporous magnesium oxide was obtained by modification with γ-aminopropyltriethoxysilane.

2. The seawater uranium extraction adsorbent according to claim 1, characterized in that, The modified one-dimensional rod-shaped mesoporous magnesium oxide was prepared using the following steps: 1) Mix magnesium chloride solution with sodium polystyrene sulfonate, add sodium carbonate solution to the resulting mixture under stirring, and then stir, allow to stand for aging, filter, dry and calcine to obtain one-dimensional rod-shaped mesoporous magnesium oxide. 2) Mix the one-dimensional rod-shaped mesoporous magnesium oxide, anhydrous ethanol, and deionized water, add γ-aminopropyltriethoxysilane to the resulting dispersion, adjust the pH of the system to 4.5-5.0, and carry out the reaction to obtain modified one-dimensional rod-shaped mesoporous magnesium oxide.

3. The seawater uranium extraction adsorbent according to claim 2, characterized in that, In step 1), the molar ratio of magnesium chloride to sodium polystyrene sulfonate is 2.5-3:0.1; the molar ratio of magnesium chloride to sodium carbonate is 1:

1.

4. The seawater uranium extraction adsorbent according to claim 2, characterized in that, The aging time in step 1) is 10-16 hours; the drying temperature is 70-75℃; the calcination temperature is 490-520℃ and the time is 2.5-4 hours.

5. The seawater uranium extraction adsorbent according to claim 1, characterized in that, In step 2), the mass ratio of the one-dimensional rod-shaped mesoporous magnesium oxide to γ-aminopropyltriethoxysilane is 1:0.08-0.12; the reaction temperature in step 2) is 55-60℃ and the reaction time is 3-5h.

6. The method for preparing the seawater uranium extraction adsorbent according to any one of claims 1-5, characterized in that, Includes the following steps: (1) The modified one-dimensional rod-shaped mesoporous magnesium oxide was mixed with N,N-dimethylformamide to obtain a suspension; (2) Add ammonia oxime to the suspension and react at 40-50℃ for 1.5-2.5h, then raise the temperature to 65-75℃ and react for 20-28h. After the reaction is completed, centrifuge and dry to obtain seawater uranium extraction adsorbent.

7. The preparation method according to claim 6, characterized in that, The amine oxime was prepared as follows: a. Mix acrylonitrile and N,N-dimethylformamide, add hydroxylamine hydrochloride, sodium carbonate and sodium hydroxide to the resulting mixture, stir and react at 45-55℃ for 1.5-2.5h, then raise the temperature to 65-75℃ and react for 20-28h to obtain the reaction system; b. Add deionized water dropwise to the reaction system, and a white precipitate will form. Filter, wash and dry the precipitate in sequence to obtain a methylamine oxime powder.

8. The preparation method according to claim 7, characterized in that, The ratio of acrylonitrile, N,N-dimethylformamide, hydroxylamine hydrochloride, sodium carbonate, and sodium hydroxide is 11-13 mmol: 18-22 mL: 11-13 mmol: 8-10 mmol: 5-7 mmol.

9. The application of the seawater uranium extraction adsorbent according to any one of claims 1-5 in seawater uranium extraction, characterized in that, The volume-to-mass ratio of seawater to adsorbent is (900-2100) L: 10g.

10. The application according to claim 9, characterized in that, The seawater in question is either concentrated seawater obtained through desalination or concentrated seawater discharged from the power plant cooling water circulation system.

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