A small particle size allophane-amidoxime polyacrylonitrile composite material for extracting uranium from seawater and a preparation method thereof

Abstract

The application discloses a small-particle-size hydrous aluminosilicate-amidoxime polyacrylonitrile composite material for extracting uranium from seawater and a preparation method thereof. The surface hydroxyl groups of nanomineral hydrous aluminosilicate are treated by using a persulfate ion, short-chain polyacrylonitrile is successfully grafted on the surface of the hydrous aluminosilicate, and the composite material is obtained after an amidoxime transformation is completed. The hydrous aluminosilicate effectively regulates the particle size of the composite material, so that the amidoxime groups can be fully exposed, and the composite material is endowed with excellent adsorption performance on uranyl ions. In addition, the synergistic effect between the hydrous aluminosilicate and the amidoxime polyacrylonitrile enables the composite material to have excellent suspensibility in a solution and excellent structural stability and high adsorption capacity on uranium in a desorption regeneration process. The composite material also has the advantages of simple preparation process, low production cost and the like, and has great application potential in the extraction of uranium from seawater.

Description

TECHNICAL FIELD

[0001] The application relates to a uranium adsorption material and a preparation method, and belongs to the fields of adsorption materials, water treatment and nuclear chemical engineering, and particularly relates to a small-particle-size allophane-amidoxime polyacrylonitrile composite material and a preparation method thereof. TECHNICAL BACKGROUND

[0002] Uranium is a basic resource for the nuclear industry, and its reserves and mining technology directly affect the national defense and energy security. Nuclear power generation, as an important clean energy, by the end of 2023, China has 55 nuclear power generating units in operation, with an annual nuclear power generation of 440,000 gigawatt-hours, accounting for nearly 5% of the country's cumulative power generation. The continuous operation of nuclear power requires stable uranium resource supply. However, the proven uranium reserves in China are only 2.8 million tons, and in the face of such high consumption, it is urgent to increase investment in uranium exploration and mining to ensure the sustainable development of nuclear power.

[0003] Due to the relatively limited uranium resources in the earth's crust, about 99.9% of the global uranium resources exist in the form of uranyl ions in seawater, so how to obtain uranium resources from seawater has become a strategic technology to ensure the sustainable development of nuclear power. Thanks to the potential contribution of seawater uranium extraction technology to energy security, it was ranked as one of the seven separation technologies that can change the world by the journal Nature in 2016. However, the concentration of uranium in seawater is extremely low (about 3.2 μg / L), and several hundred tons of uranium fuel are usually required to start a nuclear power plant, so how to efficiently enrich uranyl ions in seawater at low cost has become a key problem for the widespread promotion of nuclear power.

[0004] Since Davies et al. first published the research on seawater uranium extraction in 1964, a variety of methods for extracting uranium have been developed, including adsorption, solvent extraction, chemical precipitation, biological treatment, ion exchange and superconducting magnetic separation. Among them, adsorption method has become the focus of research due to its low cost, low energy consumption and mature technology. Polymeric materials containing amidoxime groups have high adsorption capacity and selectivity for uranyl ions, and are popular candidate materials for seawater uranium extraction adsorbents.

[0005] The large number of nitrile functional groups in acrylonitrile and its polymers can be easily converted into amidoxime groups through simple chemical reactions, making it a widely used precursor for the preparation of uranium ion adsorption materials. However, due to the limited accessibility of amidoxime groups in large-sized polymers, the actual adsorption capacity of polyacrylonitrile-based adsorption materials is far lower than the theoretical capacity. In related reports, the adsorption effect on uranium only reached 13.1 mg / g (Polyamidoxime (PAO) granules for solar-enhanced uranium extraction from seawater Environmental Science Advances 2024 3.4). Therefore, by optimizing the material structure and controlling the particle size of the polymer to increase the accessibility of the adsorption groups, it is an important direction to improve the adsorption capacity of these materials.

[0006] Chinese invention patent CN201710665074.0 discloses a kind of nanofiber material for seawater uranium extraction and its preparation method, by electrospinning nanoscale amidoxime polyacrylonitrile fiber is prepared, for uranium ion adsorption. This method solves the problem of uranium ion migration from seawater to polyacrylonitrile fiber to some extent by preparing nanofiber, and obtains a relatively stable adsorption material. However, due to the steric hindrance effect of uranium ion diffusion in the material, the adsorption effect of single polyacrylonitrile material on uranium ion is limited. Researchers try to composite two or more materials to overcome this problem. Chinese invention patent CN202210423039.9 nanometer pore structure's seawater uranium extraction adsorption material and pore size regulation preparation method by crosslinking reaction and hydrolysis reaction, with bamboo splint as matrix, amidoxime bamboo splint composite material is prepared. This material has nanometer pore structure, which significantly promotes the diffusion effect of uranium ion. However, the pretreatment process of bamboo splint matrix material is complex, and the adsorption effect of unit mass is low, which is not conducive to the industrialized application of seawater uranium extraction.

[0007] and Chinese patent CN201910269879.2 discloses a kind of mesoporous silica gel particle supported amidoxime polymer uranium adsorption material and preparation method, which is prepared by using mesoporous silica gel particle as matrix, and the finished polyacrylonitrile is loaded and converted into mesoporous silica gel particle supported amidoxime polymer uranium adsorption material.The adsorption material obtained by the process has a certain adsorption effect on uranyl ion.However, the process flow is complex, and the molecular weight of amidoxime polymer in the prepared mesoporous silica gel particle supported amidoxime polymer uranium adsorption material depends entirely on the molecular weight of polyacrylonitrile in the raw material, which is also not conducive to the industrial application of seawater uranium extraction.Therefore, selecting a composite phase with good synergy between polyacrylonitrile and through simple preparation process to obtain a composite adsorption material is a research hotspot for preparing industrial seawater uranium extraction adsorption material.

[0008] Palloid is a kind of nanoscale hydrated aluminosilicate clay mineral widely existing in volcanic ash, and its structure has unique short-range order.The outer layer is alumina octahedron, and the inner layer is silica tetrahedron, which form a nanometer hollow ball structure of 3.5-5.0 nm, and there are a large number of active aluminum hydroxyl groups on the outer surface.This structure makes palloid have large specific surface area and excellent reactivity, and has great application potential in the field of adsorption.

[0009] At present, there is no report on the application of palloid in uranium adsorption material.This is due to the complexity of inorganic-organic composite process of palloid, and the limitation of existing technology in the study of nanometer properties.Therefore, it is of great significance to develop a simple and efficient composite method and construct a small particle size palloid-amidoxime polyacrylonitrile composite material with synergistic effect for preparing high-efficiency adsorption composite material that can be used in industrial seawater uranium extraction. SUMMARY

[0010] In view of the deficiencies of the prior art, the purpose of the present application is to provide a small particle size palloid-amidoxime polyacrylonitrile composite material for seawater uranium extraction, a preparation method thereof and corresponding applications.

[0011] One of the purposes of the present application is to provide a small particle size palloid-amidoxime polyacrylonitrile composite material for seawater uranium extraction.

[0012] The second purpose of the present application is to provide a preparation method of the above-mentioned small particle size palloid-amidoxime polyacrylonitrile composite material for seawater uranium extraction.

[0013] The third purpose of the present application is to provide the application of the above-mentioned small particle size palloid-amidoxime polyacrylonitrile composite material for seawater uranium extraction.

[0014] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0015] In a first aspect, the present invention provides a small-particle-diameter alumina-ammoniated polyacrylonitrile composite material for uranium extraction from seawater. The composite material is obtained by polymerizing alumina and acrylonitrile under the initiation of persulfate ions and then performing an ammoniated reaction, wherein the alumina is nanoscale.

[0016] Preferably, the borosilicate has a particle size of 3.5~5.0 nm and a structure of nano-hollow spheres with defect pores of 0.3~0.5 nm. Preferably, the borosilicate is derived from a borosilicate suspension, which is a suspension of undried borosilicate.

[0017] Preferably, the polyacrylonitrile is prepared by polymerization of acrylonitrile monomers, and during the polymerization process, it is compounded with diaspore and finally subjected to a hydroxylamine hydrochloride solution for a hydroxylamine oxime reaction.

[0018] Preferably, the average particle size of the composite material is 26-35 nm, and the median cluster size of the composite material is 480-560 nm.

[0019] Preferably, the molar ratio of the nitrile functional group of the polyacrylonitrile to hydroxylamine hydrochloride is 1:0.1-1:10, and preferably, the relative molecular weight of the polymerized polyacrylonitrile is 70,000-80,000.

[0020] Preferably, the mass ratio of the aluminosilicate to acrylonitrile is 2:1 to 20:1.

[0021] Preferably, the hydroxylamine hydrochloride solution is prepared by dissolving hydroxylamine hydrochloride and an alkaline compound in methanol or water, wherein the alkaline compound is one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, and potassium hydroxide; the molar ratio of the alkaline compound to hydroxylamine hydrochloride is 1:0.5-1:5; and the hydroxylamine hydrochloride content in the solution is 30-60 g / L, preferably 40-55 g / L.

[0022] The aqueous alumina suspension was prepared by the following method:

[0023] A sodium orthosilicate solution (Na4SiO4) of a certain concentration is mixed with an aluminum chloride hexahydrate solution (AlCl3-6H2O) of a certain concentration. Under the condition that the silicon / aluminum molar ratio is controlled at 0.6-0.9, preferably 0.75-0.8, the mixture is stirred continuously for 0.5-2 hours. The obtained precursor is centrifuged at 3000-8000 r / min for 10-30 minutes. The white precipitate is subjected to hydrothermal treatment at 100°C for 2-48 hours. The obtained product is dialyzed with ultrapure water until the pH value is close to neutral to obtain a hydrated alumina suspension.

[0024] Preferably, the concentration of the sodium silicate solution is 0.05-0.3 mol / L, and the concentration of the aluminum chloride hexahydrate is adapted according to the concentration of the sodium silicate solution based on the silicon / aluminum molar ratio.

[0025] Secondly, the present invention provides a method for preparing a small-particle-size aluminosilicate-mercapto-oxime polyacrylonitrile composite material for uranium extraction from seawater, comprising the following steps:

[0026] a) Prepare a suspension of aluminosilicate, add a persulfate ion solution, stir and react to obtain a reaction solution;

[0027] b) Add acrylonitrile monomer to the reaction solution obtained in step a) and heat to age, forming a polyacrylonitrile / alumina composite material;

[0028] c) The composite material obtained in step b) is subjected to a methylamine oxime reaction to obtain a small-particle-size aluminosilicate-methylamine oxime-polyacrylonitrile composite material.

[0029] Preferably, the persulfate ions are derived from one or more of potassium persulfate, ammonium persulfate, or sodium persulfate, and the concentration of persulfate ions is 1~10 g / L.

[0030] Preferably, the acrylonitrile in step b) is treated by removing the anti-condensing agent through methods such as distillation.

[0031] Preferably, the amylopyridine reaction occurs in a liquid medium, which is water or any one of dimethylformamide, dimethyl sulfoxide, sulfolane, or ethyl nitrate.

[0032] Preferably, the concentration of the diatomite suspension is 10~200 g / L, and the diatomite is a synthetic suspension that has not undergone drying treatment.

[0033] The aqueous alumina suspension was prepared by the following method:

[0034] A sodium orthosilicate solution (Na4SiO4) of a certain concentration is mixed with an aluminum chloride hexahydrate solution (AlCl3-6H2O) of a certain concentration. Under the condition that the silicon / aluminum molar ratio is controlled at 0.6-0.9, preferably 0.75-0.8, the mixture is stirred continuously for 0.5-2 hours. The obtained precursor is centrifuged at 3000-8000 r / min for 10-30 minutes. The white precipitate is subjected to hydrothermal treatment at 100°C for 2-48 hours. The obtained product is dialyzed with ultrapure water until the pH value is close to neutral to obtain a hydrated alumina suspension.

[0035] Preferably, the concentration of the sodium silicate solution is 0.05-0.3 mol / L, and the concentration of the aluminum chloride hexahydrate is adapted according to the concentration of the sodium silicate solution based on the silicon / aluminum molar ratio.

[0036] Preferably, the molar ratio of the nitrile functional group of the polyacrylonitrile to hydroxylamine hydrochloride is 1:0.1-1:10, and preferably, the relative molecular weight of the polymerized polyacrylonitrile is 70,000-80,000.

[0037] Preferably, the mass ratio of the aluminosilicate to the polyacrylonitrile material is 2:1-20:1.

[0038] Preferably, the hydroxylamine hydrochloride solution is prepared by dissolving hydroxylamine hydrochloride and an alkaline compound in methanol or water, wherein the alkaline compound is one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, and potassium hydroxide; the molar ratio of the alkaline compound to hydroxylamine hydrochloride is 1:0.5-1:5; and the hydroxylamine hydrochloride content in the solution is 30-60 g / L, preferably 40-55 g / L.

[0039] Preferably, the reaction time in step a) is 0.1-3 h.

[0040] Preferably, the heating and aging time in b) is 1-4 h, preferably 2-3 h, and the reaction time for adding acrylonitrile monomer is 0.1-3 h, preferably 0.5-0.8 h.

[0041] Preferably, the oxime conversion time in step c) is 15-30 h, more preferably 18-25 h, and even more preferably 20 h.

[0042] Preferably, the obtained composite material contains CH(2933, 2856 cm⁻¹) simultaneously. -1 ), CN (1438 cm) -1 ) and C=N(1391 cm -1 Characteristic chemical bonds of amine-oxime-modified polyacrylonitrile, and Si-O-(Al) (982 cm⁻¹) -1), Si-O-Al (680 cm) -1 Characteristic chemical bonds of diaspore, etc.

[0043] Thirdly, the present invention provides an application of a small-particle-diameter aluminosilicate-mercapto-oxime polyacrylonitrile composite material for uranium extraction from seawater, which adsorbs uranyl ions at room temperature, wherein the concentration of the uranyl ions is 8-20 ppm.

[0044] Preferably, the small-particle-diameter aluminosilicate-mercapto-oxime polyacrylonitrile composite material has an adsorption capacity of 320-480 mg / g for uranyl ions at room temperature for 2-5 h, and the uranyl ion concentration is 8-20 ppm.

[0045] Preferably, the small-particle-diameter aluminosilicate-mercapto-oxime polyacrylonitrile composite material still retains an adsorption capacity of not less than 85% for uranyl ions after 5-10 regeneration cycles.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] This invention creatively utilizes the nanostructure and surface functional group properties of diatomite to construct a method for preparing a small-particle-size diatomite-mercapto-oxime polyacrylonitrile composite material and its application through a composite reaction with acrylonitrile:

[0048] 1. Utilizing the unique nanosphere structure and surface hydroxyl properties of diatomite, a diatomite-mercapto-oxime polyacrylonitrile composite material rich in uranyl ion adsorption sites was constructed. The surface of diatomite possesses numerous active hydroxyl sites, serving as both the starting and ending points for acrylonitrile polymerization. Its unique nanosphere structure allows for uniform dispersion in the reaction solution, effectively interrupting the excessively long main chain formed during acrylonitrile polymerization and preventing folding and twisting of the single-phase polyacrylonitrile due to excessive main chain length. Therefore, the fully exposed mescapto-oxime groups in the diatomite-oxime-modified polyacrylonitrile composite material significantly suppress the steric hindrance effect within the material during adsorption, enabling the composite material to efficiently capture a large number of uranyl ions, thus exhibiting excellent adsorption performance.

[0049] 2. The synergistic effect of boehmite and polyacrylonitrile endows the composite material with excellent suspension properties and structural stability. The boehmite-polyacrylonitrile composite material of this invention has an average particle size of only about 30 nm after the amylopyrification transformation, and maintains a small cluster particle size (about 542 nm) in solution, resulting in excellent suspension properties. It can remain suspended in aqueous solution for a long time, effectively avoiding sedimentation and failure of the adsorbent material during the adsorption of uranyl ions, and maintaining excellent adsorption capacity for uranyl ions in static solution. This is beneficial for the application of this material in non-powered adsorption beds in seawater uranium extraction, helping to reduce the energy consumption and maintenance costs of adsorption equipment. On the other hand, the separation of amylopyrification groups from uranyl ions requires an alkaline environment, which can lead to irreversible structural changes in the adsorbent material, such as main chain breakage. By grafting short-chain polyacrylonitrile onto the surface of boehmite, a short-chain amylopyrification polyacrylonitrile adsorption system with boehmite as the core is constructed. This short-chain polymer maintains good structural stability under alkaline conditions, significantly reducing failure caused by main chain breakage during regeneration. Therefore, this material can maintain high adsorption performance in multiple cycles, making it suitable for continuous applications such as uranium extraction from seawater.

[0050] 3. Achieving inorganic-organic polymerization through a one-step in-situ copolymerization reaction offers the advantage of a simple preparation method. Treating the hydroxyl groups on the surface of diatomite with persulfate ions promotes the polymerization between diatomite and acrylonitrile, avoiding the additional organic modification steps required in traditional inorganic-organic composite material preparation processes using silanes or other modifiers. The hydrolysis products of persulfate ions not only promote the conversion of hydroxyl groups on the diatomite surface to alkoxy radicals but also open the double bonds of acrylonitrile in subsequent reactions, initiating polymerization under relatively mild conditions. Therefore, this one-step process reduces production complexity and raw material costs, creating favorable conditions for the practical industrial application of uranyl ion adsorption materials. Attached Figure Description

[0051] Figure 1 This is the X-ray diffraction (XRD) pattern of the small-particle-size aluminosilicate-mercapto-oxime polyacrylonitrile composite material prepared in Example 1.

[0052] Figure 2 This is the Fourier transform infrared (FT-IR) spectrum of the small-particle-size aluminosilicate-mercapto-oxime polyacrylonitrile composite material prepared in Example 1.

[0053] Figure 3 This is a transmission electron microscope (TEM) image of the small-particle-size aluminosilicate-mercapto-oxime polyacrylonitrile composite material prepared in Example 2.

[0054] Figure 4This is a laser particle size distribution (LPS) image of the small-particle-size aluminosilicate-mercapto-oxime polyacrylonitrile composite material prepared in Example 2 in aqueous solution. Detailed Implementation

[0055] The present invention will be specifically described below with reference to the embodiments, but the implementation and protection scope of the present invention are not limited to the following embodiments. Example 1

[0056] 1) Take 0.5 mL of 100 g / L aluminosilicate suspension, add 9 mL of 5.56 g / L potassium persulfate solution to it and stir for 0.5 h to obtain the reaction solution.

[0057] 2) Add 0.5 mL of acrylonitrile to the reaction solution obtained in step 1) and stir for 0.5 h, then heat to 70℃ and age for 2 h to obtain polyacrylonitrile / alumina composite material.

[0058] 3) Add 5.3 g of hydroxylamine hydrochloride to 100 mL of water. After it is completely dissolved, add 3.6 g of sodium carbonate and 0.9 g of sodium hydroxide powder. Stir and then add 0.5 g of the polyacrylonitrile / diatomite composite material obtained in step 2). Heat to 70°C and maintain for 20 h to complete the amylopyrification transformation of polyacrylonitrile in the composite material, and obtain the small-particle-diatomite-amylopyrified polyacrylonitrile composite material of this embodiment.

[0059] Figure 1 The XRD pattern of this embodiment shows the presence of diffraction peaks of both ammonium oxime-modified polyacrylonitrile and hydrated alumina, indicating that the composite material contains both ammonium oxime-modified polyacrylonitrile and hydrated alumina.

[0060] Figure 2 The FT-IR spectrum of this embodiment shows that CH(2933, 2856 cm⁻¹) coexist in the composite material. -1 ), CN (1438 cm) -1 ) and C=N(1391 cm -1 Characteristic chemical bonds of amine-oxime-modified polyacrylonitrile, and Si-O-(Al) (982 cm⁻¹) -1 ), Si-O-Al (680 cm) -1 The presence of characteristic chemical bonds in diatomite further confirms the simultaneous presence of both ammonium oxime-modified polyacrylonitrile and diatomite in the composite material.

[0061] After adsorption for 5 h in 100 mL of uranyl solution containing 8 ppm uranium, the uranium adsorption capacity of the small-particle-diameter aluminosilicate-mercapto-oxime polyacrylonitrile composite material obtained in Example 1 reached 413.3 mg / g. Example 2

[0062] 1) Take 0.5 mL of 30 g / L aluminosilicate suspension, add 9 mL of 6 g / L potassium persulfate solution to it and stir for 0.5 h to obtain the reaction solution.

[0063] 2) Add 0.5 mL of acrylonitrile to the reaction solution obtained in step 1) and stir for 0.5 h, then heat to 70℃ and age for 2 h to obtain polyacrylonitrile / alumina composite material.

[0064] 3) Add 2.5 g of hydroxylamine hydrochloride to 30 mL of dimethylformamide. After it is completely dissolved, add 2.0 g of sodium carbonate and 0.5 g of sodium hydroxide powder. After stirring, add 0.1 g of the polyacrylonitrile / diatomite composite material obtained in step 2). Heat to 70°C and maintain for 20 h. Then add 2.0 g of sodium carbonate and 0.5 g of sodium hydroxide. Continue to maintain for 20 h to complete the amylopyrification transformation of polyacrylonitrile in the composite material and obtain the small-particle-diatomite-amylopyrified polyacrylonitrile composite material of this embodiment.

[0065] Figure 3 The image shown is a TEM image of this embodiment. The results show that the particle size of the aluminosilicate-amine oxime polyacrylonitrile in this example is around 30 nm, and it forms clusters of about 500 nm after drying.

[0066] Figure 4 This is a laser particle size distribution map measured in water in this embodiment. According to the cumulative particle size distribution curve, the median cluster particle size in this embodiment is 541.6 nm, indicating that the composite material synthesized in this embodiment still has a small cluster particle size in water. This proves that the addition of hydrated aluminate inhibits the aggregation of metamine oxime polyacrylonitrile in water, which is more conducive to suppressing the steric hindrance effect when uranyl ions diffuse in it.

[0067] After adsorption for 5 h in a uranyl solution containing 8 ppm uranium, the uranium adsorption capacity of the small-particle-diameter aluminosilicate-mercapto-oxime polyacrylonitrile composite material obtained in Example 2 reached 459.1 mg / g. Example 3

[0068] 1) Take 1.7 mL of 58.3 g / L aluminosilicate suspension, add 18 mL of 8 g / L ammonium persulfate solution to it and stir for 0.2 h to obtain the reaction solution.

[0069] 2) Add 1 mL of acrylonitrile to the reaction solution obtained in step 1) and stir for 0.5 h, then heat to 75℃ and age for 2 h to obtain polyacrylonitrile / alumina composite material.

[0070] 3) Add 3 g of hydroxylamine hydrochloride to 30 mL of dimethylformamide. After it is completely dissolved, add 2 g of sodium carbonate and 0.5 g of sodium hydroxide powder. Stir and then add 0.2 g of the polyacrylonitrile / diatomite composite material obtained in step 2). Heat to 75°C and maintain for 5 h to complete the amylopyrification transformation of polyacrylonitrile in the composite material, and obtain the small-particle-diatomite-amylopyrified polyacrylonitrile composite material of Example 3.

[0071] The small-particle-diameter aluminosilicate-mercapto-oxime polyacrylonitrile composite material obtained in this example achieved a uranium adsorption capacity of 327.6 mg / g after adsorption in 100 mL of uranyl solution containing 8 ppm uranium for 5 h. After desorption and regeneration 5 times in hot sodium hydroxide solution, it still retained 85.3% (279.5 mg / g) of the high-efficiency adsorption capacity. Comparative Example 1

[0072] 1) Take 2 mL of a 35 g / L mesoporous silica particle suspension, add 20 mL of an 8 g / L ammonium persulfate solution, and stir for 0.2 h to obtain a reaction solution. The mesoporous silica particles are commercial mesoporous silica with an average particle size of 200 nm and a pore size of 2 nm, obtained from Maclean's reagent M758933.

[0073] 2) Add 1 mL of acrylonitrile to the reaction solution obtained in step 1) and stir for 0.5 h, then heat to 75℃ and age for 2 h to obtain polyacrylonitrile / mesoporous silica particle composite material.

[0074] 3) Add 3 g of hydroxylamine hydrochloride to 30 mL of dimethylformamide. After it is completely dissolved, add 2 g of sodium carbonate and 0.5 g of sodium hydroxide powder. After stirring, add 0.2 g of the polyacrylonitrile / mesoporous silica particle composite material obtained in step 2). Heat to 75 °C and maintain for 5 h to complete the amylopyrification transformation of polyacrylonitrile in the composite material, and obtain the mesoporous silica particle-amylopyrified polyacrylonitrile composite material of this comparative example.

[0075] The adsorption capacity of the mesoporous silica particles-mercaptolated polyacrylonitrile composite material obtained in this comparative example reached 85.6 mg / g after adsorption in 100 mL of uranyl solution containing 8 ppm uranium for 5 h. Comparative Example 2

[0076] 1) Take 50 mg of diatomite and ultrasonically disperse it in 0.5 mL of water. Add 9 mL of potassium persulfate solution with a concentration of 5.56 g / L to the above diatomite dispersion and stir for 0.5 h to obtain a reaction solution. The diatomite is the diatomite powder obtained after drying the diatomite suspension in Examples 1-3.

[0077] 2) Add 0.5 mL of acrylonitrile to the reaction solution obtained in step 1) and stir for 0.5 h, then heat to 70℃ and age for 2 h to obtain polyacrylonitrile / alumina composite material.

[0078] 3) Add 5.3 g of hydroxylamine hydrochloride to 100 mL of water. After it is completely dissolved, add 3.6 g of sodium carbonate and 0.9 g of sodium hydroxide powder. After stirring, add 0.5 g of the polyacrylonitrile / diatomite composite material obtained in step 2). Heat to 70 °C and maintain for 20 h to complete the amylopyrification transformation of polyacrylonitrile in the composite material, and obtain the amylopyrite-amylopyrified polyacrylonitrile composite material of this comparative example.

[0079] The comparative example obtained by adsorption of hydrated aluminosilicate-mercaptolated polyacrylonitrile composite material in 100 mL of uranyl solution containing 8 ppm uranium for 5 h had an adsorption capacity of 102 mg / g. Comparative Example 3

[0080] 1) Take 25 mg of diatomite and ultrasonically disperse it in 0.5 mL of water. Add 9 mL of potassium persulfate solution with a concentration of 5.56 g / L to the above diatomite dispersion and stir for 0.5 h to obtain a reaction solution. The diatomite is the diatomite powder obtained after drying the diatomite suspension in Examples 1-3.

[0081] 2) Add 0.5 mL of acrylonitrile to the reaction solution obtained in step 1) and stir for 0.5 h, then heat to 70℃ and age for 2 h to obtain polyacrylonitrile / alumina composite material.

[0082] 3) Add 5.3 g of hydroxylamine hydrochloride to 100 mL of water. After it is completely dissolved, add 3.6 g of sodium carbonate and 0.9 g of sodium hydroxide powder. Stir and then add 0.5 g of the polyacrylonitrile / diatomite composite material obtained in step 2). Heat to 70 °C and maintain for 20 h to complete the amylopyrification transformation of polyacrylonitrile in the composite material, and obtain the comparative amylopyrite-amylopyrified polyacrylonitrile composite material.

[0083] The comparative example obtained by adsorption of hydrated aluminosilicate-mercaptolated polyacrylonitrile composite material in 100 mL of uranyl solution containing 8 ppm uranium for 5 h showed an adsorption capacity of 35 mg / g. Comparative Example 4

[0084] 1) Take 50 mg of sodium montmorillonite and ultrasonically disperse it in 0.5 mL of water. Add 9 mL of potassium persulfate solution with a concentration of 5.56 g / L to the sodium montmorillonite dispersion and stir for 0.5 h to obtain a reaction solution. The sodium montmorillonite is a nano-sized powder.

[0085] 2) Add 0.5 mL of acrylonitrile to the reaction solution obtained in step 1) and stir for 0.5 h, then heat to 70℃ and age for 2 h to obtain polyacrylonitrile / sodium montmorillonite composite material.

[0086] 3) Add 5.3 g of hydroxylamine hydrochloride to 100 mL of water. After it is completely dissolved, add 3.6 g of sodium carbonate and 0.9 g of sodium hydroxide powder. After stirring, add 0.5 g of the polyacrylonitrile / sodium montmorillonite composite material obtained in step 2). Heat to 70 °C and maintain for 20 h to complete the amylopyrification transformation of polyacrylonitrile in the composite material, and obtain the sodium montmorillonite-amylopyrified polyacrylonitrile composite material of this comparative example.

[0087] The sodium-based montmorillonite-mercaptolated polyacrylonitrile composite material obtained in this comparative example had an adsorption capacity of 62 mg / g after adsorption in 100 mL of uranyl solution containing 8 ppm uranium for 5 h.

[0088] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A small-particle-size aluminosilicate-mercapto-oxime polyacrylonitrile composite material for uranium extraction from seawater, characterized in that, The composite material is obtained by polymerizing diatomite and acrylonitrile under the initiation of persulfate ions and then by a amine oxime reaction, wherein the diatomite is nanoscale; the particle size of the diatomite is 3.5-5.0 nm, and the diatomite has a nano-hollow sphere structure with defect pores of 0.3-0.5 nm, and the diatomite is derived from a diatomite suspension; The polyacrylonitrile is prepared by polymerization of acrylonitrile monomers and is compounded with diatomite during the polymerization process, and finally subjected to a hydroxylamine hydrochloride solution for a hydroxylamine oxime reaction. The average particle size of the composite material is 26-35 nm, and the median cluster size is 480-560 nm. The alumina suspension is prepared by the following method: a sodium orthosilicate solution of a certain concentration is mixed with an aluminum chloride hexahydrate solution of a certain concentration; under the condition of controlling the silicon / aluminum molar ratio of 0.6-0.9, the mixture is continuously stirred for 0.5-2 hours; the obtained precursor is centrifuged at 3000-8000 r / min for 10-30 minutes; the white precipitate is subjected to hydrothermal treatment at 100℃ for 2-48 hours; the obtained product is dialyzed with ultrapure water until the pH value is close to neutral to obtain the alumina suspension.

2. The preparation method of the small-particle-size hydrated aluminosilicate-mercapto-oxime polyacrylonitrile composite material for uranium extraction from seawater according to claim 1, characterized in that, Includes the following steps: a) Add persulfate ion solution to the aluminosilicate suspension, stir and react to obtain a reaction solution; b) Add acrylonitrile monomer to the reaction solution obtained in step a) and heat to age it to form a polyacrylonitrile / alumina composite material; c) The composite material obtained in step b) is subjected to a methylamine oxime reaction to obtain a small-particle-size aluminosilicate-methylamine oxime-polyacrylonitrile composite material. The alumina suspension is prepared by the following method: a sodium orthosilicate solution of a certain concentration is mixed with an aluminum chloride hexahydrate solution of a certain concentration; under the condition of controlling the silicon / aluminum molar ratio of 0.6-0.9, the mixture is continuously stirred for 0.5-2 hours; the obtained precursor is centrifuged at 3000-8000 r / min for 10-30 minutes; the white precipitate is subjected to hydrothermal treatment at 100℃ for 2-48 hours; the obtained product is dialyzed with ultrapure water until the pH value is close to neutral to obtain the alumina suspension.

3. The preparation method according to claim 2, characterized in that, The persulfate ions are derived from one or more of potassium persulfate, ammonium persulfate, or sodium persulfate, and the concentration of persulfate ions is 1–10 g / L.

4. The preparation method according to claim 3, characterized in that, The amylopyridine oxime reaction occurs in a liquid medium, which is water or any one of dimethylformamide, dimethyl sulfoxide, sulfolane, or ethyl nitrate.

5. The preparation method according to claim 4, characterized in that, The concentration of the aluminosilicate suspension is 10–200 g / L.

6. The application of the small-particle-size hydrated aluminosilicate-mercapto-oxime polyacrylonitrile composite material for uranium extraction from seawater according to claim 1, characterized in that: Uranyl ions are adsorbed at room temperature, with a concentration of 8-20 ppm.

7. The application according to claim 6, characterized in that, The adsorption capacity is 320-480 mg / g at room temperature for 2-5 hours.

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