A material capable of adsorbing uranium from wastewater and its preparation method

Abstract

This invention discloses a material capable of adsorbing uranium from wastewater, particularly a material for treating uranium-containing wastewater, and a method for preparing this material. The uranium-adsorbing material of this invention consists of a superparamagnetic Fe3O4 magnetic core and an ordered mesoporous SiO2 shell on the surface of the magnetic core. The synthesized magnetic mesoporous material has a specific surface area of ​​300-400 m² / g. 2 / g. The magnetic Fe3O4 of this invention coats ordered mesoporous SiO2, while simultaneously creating a hollow structure between Fe3O4 and SiO2, which synergistically generates a larger specific surface area, providing a good platform for the grafting of functional groups. More importantly, compared with disordered mesopores, the ordered mesopores and hollow structure not only minimize the shielding effect on the magnetic Fe3O4 core, ensuring good magnetism and thus achieving rapid magnetic separation, but also increase the specific surface area of ​​the particles while effectively preventing aggregation. The functional magnetic nanomaterials obtained by this invention are used for the removal of uranium from uranium-containing water bodies, exhibiting good adsorption performance for uranium and a wide applicable pH range (0.5-10.5).

Description

Technical Field

[0001] This invention relates to a material capable of adsorbing uranium in wastewater, particularly a material for treating uranium-containing wastewater, and a method for preparing such a material. Background Technology

[0002] With the rapid development of science and technology and the economy, fossil fuels such as coal and oil are being rapidly depleted. Nuclear energy, due to its high efficiency, cleanliness, and economy, has emerged as a popular choice and has attracted widespread attention. Currently, vigorously developing nuclear power has become a focus and active pursuit for most countries. The rational use of nuclear energy will greatly alleviate global resource shortages and bring significant economic benefits. However, the development of nuclear energy generates a large amount of uranium-containing wastewater. How to achieve the economical and efficient purification of this wastewater has become a major challenge facing the world.

[0003] In recent years, adsorption methods have gained widespread research and recognition due to their high efficiency, low cost, and broad applicability, and have attracted considerable attention in the purification of uranium-containing wastewater. However, the application of traditional materials is limited by their small specific surface area, low adsorption capacity, poor selectivity, and difficulty in solid-liquid / solid-liquid separation, which can lead to secondary pollution. While emerging functional materials such as carbon materials, MOFs, and COFs have achieved significantly higher specific surface areas through structural adjustments, enhancing their uranium adsorption capacity, they still face the challenge of separating the adsorbent from the wastewater. Therefore, designing and synthesizing uranium-containing wastewater purification materials with high adsorption capacity, good selectivity, and easy separation has become an urgent problem to solve.

[0004] Magnetic nanoparticles possess unique quantum size effects, surface interface effects, and magnetic effects, enabling convenient and rapid solid-solid / solid-liquid separation through an applied gradient magnetic field, thus showing promising potential in uranium-containing wastewater treatment. However, in practical applications, magnetic nanoparticles tend to agglomerate into larger particles, leading to reduced reactivity and surface utilization efficiency. Furthermore, agglomerated magnetic nanoparticles also reduce their mobility. To address this rapid magnetic response characteristic, the particle size of magnetic materials can be reduced to the micrometer or even nanometer scale, thereby increasing their specific surface area and adsorption capacity. Summary of the Invention

[0005] This invention provides a material that overcomes the shortcomings of existing technologies and can be used to remove uranium from uranium-containing wastewater, and also provides a method for preparing this material.

[0006] The uranium-absorbing material in this invention is composed of a superparamagnetic Fe3O4 magnetic core and an ordered mesoporous SiO2 shell on the surface of the magnetic core. The specific surface area of ​​the synthesized magnetic mesoporous material is 300-400 m². 2 / g, within the theoretically achievable maximum specific surface area range (300-400m²).2 Within a range of / g), this provides a broad platform for the grafting of functional groups, which helps to improve the grafting rate of functional groups and enhance the adsorption performance of the material for U.

[0007] Furthermore, the uranium-absorbing material in the wastewater of the present invention is modified with P=O and -NH2 groups at the mesopores of the aforementioned material.

[0008] Preferably, the magnetic mesoporous material of the present invention, which can adsorb uranium materials in wastewater, has a specific surface area of ​​318 m². 2 / g.

[0009] The method for preparing uranium-absorbing materials from wastewater according to the present invention is as follows:

[0010] 1) Add Fe3O4 to a mixture of ethanol / water / ammonia in a volume ratio of 10-25 / 1-3 / 1-5, and sonicate to uniformly disperse Fe3O4 in the solution. Then add a small amount (0.1-0.5 mL) of tetraethyl orthosilicate (TEOS) to the solution and continue the reaction at room temperature for 8 hours to remove impurities and moisture. Then dry the solution to obtain brown Fe3O4@SiO2.

[0011] 2) The Fe3O4@SiO2 obtained in the previous step was dispersed in a mixture of ethanol / water / triethanolamine. Ultrasonic reaction was used to ensure uniform dispersion of the material in the solution. 0.1-1.0 g of hexadecyltrimethylammonium bromide (CTAB) and 0.1-0.5 g of sodium salicylate were added as template agents. The optimal mass addition range was 0.2-0.5 g of CTAB and 0.2-0.5 g of sodium salicylate. After reacting at 35°C for 1 hour, 0.1-0.5 mL of tetraethyl orthosilicate (TEOS) and 0.1-0.5 mL of 1,2-bis(triethoxysilyl)ethane (BTSE) were added dropwise. The optimal volume addition range for TEOS and BTSE was 0.1-0.3 mL of TEOS and 0.1-0.3 mL of BTSE. After sufficient reaction, the product was separated, and impurities and moisture were removed. After drying, brown Fe3O4@v-SiO2 was obtained.

[0012] 3) Disperse the product obtained in the above step in a mixture of ethanol and concentrated hydrochloric acid, and continue to react at 60°C to remove hexadecyltrimethylammonium bromide, to obtain Fe3O4@v-mSiO2;

[0013] 4) Disperse Fe3O4@v-mSiO2 in a mixture of ethanol and distilled water, then add 0.5-2 ml of silane coupling agent γ-methacryloyloxypropyltrimethoxysilane (KH570) and 0.5-5 ml of NH3·H2O in sequence. After the reaction is fully carried out under ultrasonic and mechanical stirring, separate the product, and then dry it to obtain surface-activated Fe3O4@v-mSiO2 microspheres.

[0014] 5) Next, the surface-activated Fe3O4@v-mSiO2 microspheres were dispersed in acetonitrile, and then azobisisobutyronitrile (AIBN) was added. After complete dissolution, diallylamine (DMAA) and di(methacryloyloxyethyl) phosphate (DMP) were added sequentially. The slow heating rate facilitated thorough mixing and reaction between the unfunctionalized material and the organic components, increasing the grafting rate of functional groups. If the heating rate were too fast, it would lead to excessively rapid polymerization of the organic matter, reducing the grafting rate of the organic groups in the material itself and affecting subsequent adsorption efficiency. Therefore, the heating rate was increased by 1 liter per minute in the experiment. The mixture is heated to a certain temperature at a rate of ℃. At this temperature, the reaction will exhibit boiling and reflux, which helps to improve the uniformity of the reaction and enhance the uniformity of the grafting of bifunctional groups (P=O and -NH2 groups). If the heating temperature is below 80℃, the reaction will not boil, resulting in insufficient and incomplete organic reaction. Therefore, the heating temperature range needs to be set at 90-95℃, and the reaction should be continued at this temperature for 1 hour. After separation, the product is dried to obtain the functional mesoporous magnetic nanomaterial Fe3O4@v-mSiO2-P (DMAA-DMP) of this invention.

[0015] In the preparation method of the present invention, diallylamine (DMAA) contains -NH2 and di(methacryloyloxyethyl) phosphate (DMP) contains P=O. Both are carriers of bifunctional groups. By fully mixing with unfunctionalized core-shell mesoporous matrix materials and undergoing organic polymerization reaction, the bifunctional groups can be successfully grafted onto the material mesopores and surface in one step.

[0016] The specific steps of the method for preparing uranium materials that can adsorb wastewater according to the present invention are as follows:

[0017] 1) Add 0.4g Fe3O4 to a mixture of ethanol / water / ammonia (volumes of 180, 10, and 8mL respectively), and sonicate for 15min to uniformly disperse the material in the solution. Then add 0.8mL of tetraethyl orthosilicate (TEOS) to the solution and continue the reaction at room temperature for 8h. After the reaction is completed, separate the product with an external magnetic field to remove impurities and water, and then dry it in a vacuum environment at 60℃ for 12h to obtain brown Fe3O4@SiO2.

[0018] 2) 0.1 g Fe3O4@SiO2 was dispersed in a mixture of ethanol / water / triethanolamine (volumes of 30, 75, and 0.3 mL, respectively). The mixture was sonicated for 15 min to uniformly disperse the material in the solution. A certain amount of template agent (0.5 g cetyltrimethylammonium bromide and 0.3 g sodium salicylate) was added. The mixture was reacted at 35 °C for 1 h. Then, 0.125 mL TEOS and 0.125 mL BTSE were added dropwise. The mixture was reacted at 35 °C for 24 h. After the reaction was completed, the product was separated by an external magnetic field to remove impurities and water. The product was then dried in a vacuum environment at 60 °C for 12 h to obtain brown Fe3O4@v-SiO2.

[0019] 3) The above product was dispersed in a mixture of 60 mL ethanol and 0.06 mL concentrated hydrochloric acid, and the reaction was continued at 60 °C for 3 h to remove CTAB and obtain Fe3O4@v-mSiO2.

[0020] 4) Disperse 0.1g Fe3O4@v-mSiO2 in a mixture of 128ml ethanol and 36.0ml distilled water, then add 2ml KH570 and 40ml NH3·H2O sequentially. React for 12h under ultrasonic and mechanical stirring. After the reaction is complete, separate the product with an external magnetic field to remove impurities and moisture, and then dry it in a vacuum environment at 60℃ for 12h to obtain surface-activated Fe3O4@v-mSiO2.

[0021] 5) Next, 0.06 g of surface-activated Fe3O4@v-mSiO2 microspheres were weighed and dispersed in a 150 mL three-necked flask containing 80.0 mL of acetonitrile. Then, 8 g of AIBN was added. After complete dissolution, 2 g of DMAA and 2 g of DMP were added sequentially. The mixture was heated to 90 °C at a rate of 1 °C per minute and the reaction was continued at this temperature for 1 h. After the reaction was completed, the product was separated by an external magnetic field to remove impurities and moisture. Then, it was dried in a vacuum environment at 60 °C for 12 h to obtain the uranium adsorption material in the wastewater of the present invention—functional mesoporous magnetic nanomaterial Fe3O4@v-mSiO2-P (DMAA-DMP).

[0022] To address the problems of small specific surface area, low adsorption capacity, poor selectivity, and difficulty in solid-liquid / solid-liquid separation in traditional materials, this invention uses superparamagnetic Fe3O4 as the magnetic core and introduces mesoporous SiO2 onto its surface. By optimizing the synthesis conditions, an ordered mesoporous SiO2 shell is obtained. Compared to disordered mesopores, the ordered mesopores significantly reduce the shielding effect on the magnetic response. Furthermore, the creation of a hollow structure between the magnetic core and the ordered mesoporous SiO2 facilitates further increases in specific surface area. Therefore, the ordered mesopores and hollow structure provide a good platform for subsequent grafting of functional groups. P=O and -NH2 groups, which have specific chelating ability for uranium, are modified onto the above-mentioned mesoporous magnetic material. The grafting rate of functional groups is improved by a combination of ultrasonication, stirring, and reflux, ultimately yielding a novel magnetic solid-phase adsorbent with high selectivity, easy separation, rapid adsorption kinetics, high adsorption capacity, and multiple reusability. This invention combines structural regulation and surface modification to endow the material with excellent adsorption performance and selectivity, enabling rapid and efficient purification of acidic and neutral uranium-containing wastewater. Coating the surface of Fe3O4 with mesoporous SiO2 imparts magnetism and a high specific surface area while significantly reducing agglomeration. Introducing a hollow structure between Fe3O4 and mesoporous SiO2 to obtain Fe3O4@v-mSiO2 further increases the specific surface area of ​​the material, thus providing more platforms for functional groups and achieving a higher grafting rate. The N and P in the -NH2 and P=O groups coordinate synergistically with uranium, thereby significantly enhancing the material's specific adsorption and adsorption capacity for uranium.

[0023] In summary, the functional mesoporous magnetic nanomaterial Fe3O4@v-mSiO2-P (DMAA-DMP) prepared by loading bifunctional groups (-NH2 and P=O groups) onto Fe3O4@v-mSiO2 in this invention can achieve highly efficient and specific adsorption of uranium under various ion coexistence conditions, while exhibiting rapid adsorption kinetics. Furthermore, the adsorption performance is minimally affected by the acidity of uranium-containing wastewater, maintaining good selectivity and ideal adsorption capacity even in highly acidic environments (pH=0.5). In addition, the material exhibits good reusability, achieving uranium desorption within as little as 5 minutes and can be reused at least 11 times while maintaining the material structure. Therefore, this invention provides an effective strategy for the rational design and preparation of highly efficient uranium enrichment and extraction materials.

[0024] The material of this invention is used to remove uranium from uranium-containing wastewater. Its combination of structural regulation and surface modification endows the material with excellent adsorption performance and selectivity, enabling rapid and efficient purification of both acidic and neutral uranium-containing wastewater, and exhibiting specific adsorption and adsorption capacity. In summary, the functional mesoporous magnetic nanomaterial Fe3O4@v-mSiO2-P (DMAA-DMP), prepared by loading bifunctional groups (-NH2 and P=O groups) onto Fe3O4@v-mSiO2 in this invention, can achieve efficient and specific adsorption of uranium under various ion coexistence conditions, while exhibiting rapid adsorption kinetics. Furthermore, the adsorption performance is minimally affected by the acidity of the uranium-containing wastewater, maintaining good selectivity and ideal adsorption capacity even in highly acidic environments (pH=0.5). Moreover, the material exhibits good reusability, achieving uranium desorption within as little as 5 minutes and can be reused at least 11 times while maintaining the material structure. In conclusion, this invention provides an effective strategy for the rational design and preparation of efficient uranium enrichment and extraction materials.

[0025] The advantages and positive effects of this invention are as follows:

[0026] 1) Coating magnetic Fe3O4 with ordered mesoporous SiO2, while simultaneously creating a hollow structure between Fe3O4 and SiO2, synergistically generates a larger specific surface area, providing a good platform for the grafting of functional groups. More importantly, compared to disordered mesopores, ordered mesopores and hollow structures not only minimize the shielding effect on the magnetic Fe3O4 core, ensuring good magnetism and thus achieving rapid magnetic separation, but also effectively prevent agglomeration while increasing the specific surface area of ​​the particles. The P=O group can specifically chelate with uranium, and the N element in the -NH2 group has lone pair electrons that can coordinate with uranium. By grafting bifunctional groups (-NH2 and P=O groups), the specific adsorption effect of the material on uranium can be effectively improved. Combining the above technologies, this invention finally produces a functional mesoporous magnetic nanomaterial Fe3O4@v-mSiO2-P (DMAA-DMP) that is not prone to agglomeration, has a well-developed surface, good magnetic properties, excellent selectivity for uranium, and high adsorption capacity.

[0027] 2) The functional magnetic nanomaterials obtained in this invention are used for the removal of uranium from uranium-containing water bodies, exhibiting excellent adsorption performance and a wide applicable pH range (0.5-10.5). Adsorption experiments show that the material has a maximum adsorption capacity of 463 mg / g for uranium, and can also achieve an adsorption capacity of 114 mg / g under high acid conditions (pH=0.5), which is significantly better than similar materials reported to date. Therefore, the functional mesoporous magnetic nanomaterials prepared in this invention show great potential in the treatment of neutral and acidic uranium-containing wastewater and are expected to be applied to the efficient purification treatment of uranium-containing wastewater under real-world conditions. Attached Figure Description

[0028] Figure 1 These are morphological images of intermediate products at different stages in the preparation process of the material of this invention, wherein: Figure 1 A and Figure 1 B is Fe3O4. Figure 1 C and Figure 1 D represents Fe3O4@SiO2. Figure 1 E, Figure 1 F, Figure 1 G and Figure 1 H represents Fe3O4@v-mSiO2. Figure 1 I and Figure 1 J represents Fe3O4@v-mSiO2-P(DMAA-DMP) of this invention.

[0029] Figure 2 These are the BET spectra and mesopore distribution diagrams of the functional mesoporous magnetic nanomaterial Fe3O4@v-mSiO2-P (DMAA-DMP).

[0030] Figure 3 This is the XRD pattern of the functional mesoporous magnetic nanomaterial Fe3O4@v-mSiO2-P (DMAA-DMP).

[0031] Figure 4 It is the hysteresis loop of the functional mesoporous magnetic nanomaterial Fe3O4@v-mSiO2-P (DMAA-DMP).

[0032] Figure 5 This is the FT-IR image of the functional mesoporous magnetic nanomaterial Fe3O4@v-mSiO2-P (DMAA-DMP).

[0033] Figure 6 These are the experimental results of the acid and alkali resistance of the functional mesoporous magnetic nanomaterial Fe3O4@v-mSiO2-P (DMAA-DMP).

[0034] Figure 7 It is the adsorption pH boundary of the functional mesoporous magnetic nanomaterial Fe3O4@v-mSiO2-P(DMAA-DMP).

[0035] Figure 8 These are adsorption isotherms of the functional mesoporous magnetic nanomaterial Fe3O4@v-mSiO2-P (DMAA-DMP) at different temperatures.

[0036] Figure 9 This is the adsorption selectivity result of the functional mesoporous magnetic nanomaterial Fe3O4@v-mSiO2-P(DMAA-DMP).

[0037] Figure 10This is a result of the reusability of the functional mesoporous magnetic nanomaterial Fe3O4@v-mSiO2-P (DMAA-DMP).

[0038] Figure 11 This is the fine XPS spectrum of U.

[0039] Figure 12 This is a comparison of fine C spectra before and after adsorption of the functional mesoporous magnetic nanomaterial Fe3O4@v-mSiO2-P (DMAA-DMP). Detailed Implementation

[0040] The present invention will be explained in conjunction with embodiments.

[0041] The synthesis steps of the material of this invention are as follows:

[0042] Step 1: Dissolve 3.25g ferric chloride hexahydrate, 1.3g sodium citrate, and 6.0g sodium acetate in 100mL ethylene glycol, heat to 170℃ and react for 1h to obtain a uniform brown liquid. Transfer the liquid to a polytetrafluoroethylene reactor for hydrothermal reaction at 200℃ for 10h. After the reaction is complete, separate the product using an external magnetic field to remove impurities and moisture, and then dry it under vacuum at 60℃ for 12h to obtain black Fe3O4.

[0043] Step 2: Add 0.4g Fe3O4 to a mixture of ethanol / water / ammonia (volumes 180, 10, and 8mL respectively), and sonicate for 15min to uniformly disperse the material in the solution. Then, add 0.8mL of tetraethyl orthosilicate (TEOS) dropwise to the solution and continue the reaction at room temperature for 8h. After the reaction is complete, separate the product using an external magnetic field to remove impurities and moisture, and then dry it in a vacuum environment at 60℃ for 12h to obtain brown Fe3O4@SiO2.

[0044] Step 3: Disperse 0.1g Fe3O4@SiO2 in a mixture of ethanol / water / triethanolamine (volumes of 30, 75, and 0.3mL respectively), and sonicate for 15min to uniformly disperse the material in the solution. Add a certain amount of template agent (0.5g hexadecyltrimethylammonium bromide and 0.3g sodium salicylate), and continue the reaction at 35℃ for 1h. Then add 0.125mL LTEOS and 0.125mL BTSE, and continue the reaction at 35℃ for 24h. After the reaction is completed, separate the product with an external magnetic field to remove impurities and moisture, and then dry it in a vacuum environment at 60℃ for 12h to obtain brown Fe3O4@v-SiO2.

[0045] Step 4: Disperse the above product in a mixture of 60 mL ethanol and 0.06 mL concentrated hydrochloric acid, and continue the reaction at 60 °C for 3 h to remove CTAB (this step is repeated twice to completely remove the template agent) to obtain Fe3O4@v-mSiO2.

[0046] Step 5: Disperse 0.1g Fe3O4@v-mSiO2 in a mixture of 128ml ethanol and 36.0ml distilled water, then add 2ml KH570 and 40ml NH3·H2O sequentially. React for 12h under ultrasonic and mechanical stirring. After the reaction is complete, separate the product with an external magnetic field to remove impurities and moisture, and then dry it in a vacuum environment at 60℃ for 12h to obtain surface-activated Fe3O4@v-mSiO2. Next, 0.06 g of surface-activated Fe3O4@v-mSiO2 microspheres were weighed and dispersed in a 150 mL three-necked flask containing 80.0 mL of acetonitrile. Then, 8 g of AIBN was added, and after complete dissolution, 2 g of DMAA and 2 g of DMP were added sequentially. The mixture was heated to 90 °C at a rate of 1 °C per minute and the reaction was continued at this temperature for 1 h. After the reaction was completed, the product was separated by an external magnetic field to remove impurities and moisture. Then, it was dried in a vacuum environment at 60 °C for 12 h to obtain the uranium adsorbent material in wastewater of the present invention—functional mesoporous magnetic nanomaterial Fe3O4@v-mSiO2-P (DMAA-DMP).

[0047] The morphology of Fe3O4@v-mSiO2-P(DMAA-DMP) obtained in this invention and its intermediate products in the synthesis process are as follows: Figure 1 As shown, due to the small particle size and large surface energy of nano-Fe3O4, and the magnetic attraction between particles, magnetic Fe3O4 nanoparticles have a strong tendency to aggregate into larger particles. This technology successfully modulates the morphology of Fe3O4 nanoparticles. Figure 1 Disordered dense SiO2 loaded on surfaces A, B) Figure 1 C,D) were converted into hollow mesoporous SiO2 ( Figure 1 G) thus yields Fe3O4@v-mSiO2( Figure 1 E, F) effectively reduced the surface energy of magnetic Fe3O4, decreased the interaction between nanoparticles, thereby stabilizing the nanoparticles and preventing their aggregation. Its specific surface area is 318 m². 2 / g, which is nearly 10 times that of the magnetic core Fe3O4, and has mesopores with a diameter of ~3nm ( Figure 2 This is consistent with the TEM results. Figure 1 H) remains consistent. XRD pattern of Fe3O4@v-mSiO2 ( Figure 3The (100) and (110) crystal planes in the figure demonstrate that SiO2 exists in a hexagonal mesoporous form. This provides a broad platform for subsequent grafting of bifunctional groups, thereby increasing the grafting amount of functional groups. The morphology of the final product, the functionalized mesoporous magnetic nanomaterial Fe3O4@v-mSiO2-P (DMAA-DMP), is as follows: Figure 1 As shown in Figures I and J, the material retains its spherical morphology and exhibits improved particle dispersion. This technique achieves good water solubility by further modifying the functional groups on the Fe3O4@v-mSiO2 surface, while simultaneously enhancing the material's specific adsorption capacity for U. This technique contributes to developing the application potential of magnetic nanomaterials in uranium-containing wastewater treatment. Compared to other nanomaterials, magnetic nanomaterials possess excellent magnetic response, enabling efficient and rapid solid-liquid separation through an external magnetic field, thus saving time and reducing secondary environmental pollution caused by incomplete separation of adsorbent materials. The material prepared in this invention exhibits good magnetic properties, with a magnetic strength of 24.4 emu / g at 20 kOe, achieving complete solid-liquid separation within 10 seconds. This provides significant convenience for uranium-containing wastewater treatment and lays a good foundation for material reuse. See [link to related information]. Figure 4 FT-IR spectrum ( Figure 5 The newly emerging 3300-3500cm -1 The absorption peaks between 1190 and 1070 cm⁻¹ represent the stretching vibration of NH₃. -1 The nearby absorption peak originates from -NH2, indicating the presence of -NH2. Furthermore, at 1160 cm⁻¹... -1 The left and right peaks are characteristic of P=O, indicating the presence of the P=O group and confirming the successful synthesis of mesoporous magnetic nanospheres Fe3O4@v-mSiO2-P (DMAA-DMP) modified with NH2 and P=O bifunctional groups. Furthermore, acid and alkali resistance experiments show... Figure 6 The material exhibits good stability over a wide pH range, particularly under high acid conditions (pH=0.5), where only 2.8% Fe and 4.2% P dissolve, indicating its great potential for treating acidic radioactive waste.

[0048] Uranium adsorption performance testing: A certain amount of Fe3O4@v-mSiO2-P (DMAA-DMP) and 6 mL of suspension (including the calculated initial U(VI) concentration and NaCl solutions of different concentrations) were subjected to adsorption experiments in 10 mL centrifuge tubes. The pH of the solution was adjusted by adding negligible volumes of NaOH and HCl solutions. The reaction mixture was then placed on a shaker at 298 K and mixed at 100 rpm for 2 hours to reach adsorption equilibrium. Finally, the adsorbent material was enriched and recovered using an external magnetic field. A certain volume of the supernatant was collected, and the residual concentration of U(VI) in the supernatant was determined spectrophotometrically at 652 nm using azoarsine as a colorimetric reagent, thereby calculating the adsorbed U concentration. In addition, some experiments (ion-selective adsorption experiments) used ICP-OES to test the U concentration.

[0049] Experimental results show that the Fe3O4@v-mSiO2-P(DMAA-DMP) of this invention exhibits good adsorption performance under pH conditions ranging from 0.5 to 10. (See [link to relevant documentation]). Figure 7 At pH 0.5, the adsorption capacity can reach 114 mg / g, which is a relatively high adsorption level among currently reported magnetic nanomaterials. This can be seen from the adsorption isotherm. Figure 8 At pH 6.0, the theoretical maximum adsorption capacity reaches 463 mg / g (298 K), and the adsorption capacity increases to 550 mg / g (333 K) with increasing pH and temperature. Simultaneously, it exhibits adsorption capacity in the presence of multiple ions (UO2). 2+ ,La 3+ Eu 3+ ,Sr 2+ Ca 2+ Mg 2+ ,Ba 2+ Zn 2+ ,Cr 2+ Ni 2+ ,Cs + Under coexisting conditions, the material of this invention exhibits excellent adsorption selectivity for uranium, see [link to relevant documentation]. Figure 9 An adsorption-desorption cycle experiment was conducted 11 times using a 0.2 mol / L Na₂CO₃ solution as the desorbent. It was found that the solution could be recycled 11 times while maintaining an adsorption capacity of over 90% under unchanged operating conditions and with guaranteed adsorption efficiency. Figure 10 As shown, the XPS spectrum of the adsorbed state U ( Figure 11 It can be seen that during the adsorption of U(VI) by functional magnetic nanomaterials, uranium exists in the hexavalent form, and there is no reduction process. The specific and efficient adsorption of U by this material originates from bifunctional groups (-NH2 and P=O groups, such as...) Figure 12 (As shown) It specifically chelates with uranyl ions, thereby undergoing chemisorption.

Claims

1. A method for preparing an adsorbent material that can efficiently adsorb uranium from wastewater within a pH range of 0.5 to 10 and is easily separable, wherein the high efficiency refers to a minimum adsorption capacity greater than or equal to 114 mg / g, characterized in that: 1) Add Fe3O4 to a mixture of ethanol / water / ammonia in a volume ratio of 10~25 / 1~3 / 1~5, and sonicate to uniformly disperse Fe3O4 in the solution. Then add 0.1-0.5 mL of tetraethyl orthosilicate (TEOS) dropwise to the solution and continue the reaction at room temperature for 8 hours to remove impurities and moisture. Then dry the solution to obtain brown Fe3O4@SiO2. 2) The Fe3O4@SiO2 obtained in the previous step was dispersed in a mixture of ethanol / water / triethanolamine. The mixture was ultrasonically reacted to ensure that the material was uniformly dispersed in the solution. A template agent consisting of 0.1-1.0 g of hexadecyltrimethylammonium bromide (CTAB) and 0.1-0.5 g of sodium salicylate was added. After the reaction was complete, 0.1-0.5 mL of tetraethyl orthosilicate (TEOS) and 0.1-0.5 mL of 1,2-bis(triethoxysilyl)ethane (BTSE) were added dropwise. After the reaction was complete, the product was separated and impurities and water were removed. After drying, brown Fe3O4@v-SiO2 was obtained. 3) Disperse the product obtained in the above step in a mixture of ethanol and concentrated hydrochloric acid, and continue to react at 60°C to remove hexadecyltrimethylammonium bromide, to obtain Fe3O4@v-mSiO2; 4) Fe3O4@v-mSiO2 was dispersed in a mixture of ethanol and distilled water, and then 0.5-2 ml of silane coupling agent γ-methacryloyloxypropyltrimethoxysilane KH570 and 0.5-5 mL of NH3·H2O were added sequentially. After the reaction was fully carried out under ultrasonic and mechanical stirring, the product was separated and dried to obtain surface-activated Fe3O4@v-mSiO2 microspheres. 5) Surface-activated Fe3O4@v-mSiO2 microspheres were dispersed in acetonitrile, and then 0.05-0.2 g of azobisisobutyronitrile (AIBN) was added. After complete dissolution, 0.2-1 mL of DMAA and 0.2-1 mL of DMP were added sequentially. After adding DMAA and DMP, the mixture was heated to 90-95°C at a rate of 1°C per minute. After the reaction was carried out at this temperature, the product was separated and then dried to obtain the functional mesoporous magnetic nanomaterial Fe3O4@v-mSiO2-P (DMAA-DMP) of the present invention.

2. The method for preparing the adsorbent material according to claim 1, characterized in that: In step 2), a template agent consisting of 0.2-0.5 g of cetyltrimethylammonium bromide (CTAB) and 0.2-0.5 g of sodium salicylate is added.

3. The method for preparing the adsorbent material according to claim 1 or 2, characterized in that: 1) 0.4 g Fe3O4 was added to 198 mL of a mixture of ethanol / water / ammonia, with a volume ratio of ethanol / water / ammonia of 180 / 10 / 8. The mixture was sonicated for 15 min to uniformly disperse the material in the solution. Then, 0.8 mL of tetraethyl orthosilicate (TEOS) was added dropwise to the solution. The reaction was continued at room temperature for 8 h. After the reaction was completed, the product was separated by an external magnetic field to remove impurities and water. Then, the product was dried in a vacuum environment at 60 °C for 12 h to obtain brown Fe3O4@SiO2. 2) 0.1 g Fe3O4@SiO2 was dispersed in 105.3 mL of a mixture of ethanol / water / triethanolamine with volumes of 30, 75, and 0.3 mL, respectively. The volumes of ethanol / water / triethanolamine were 30 / 75 / 0.3 mL. The mixture was sonicated for 15 min to uniformly disperse the material in the solution. 0.5 g cetyltrimethylammonium bromide and 0.3 g sodium salicylate were added as template agents. The mixture was reacted at 35 °C for 1 h. Then, 0.125 mL TEOS and 0.125 mL BTSE were added dropwise, and the mixture was reacted at 35 °C for 24 h. After the reaction was completed, the product was separated, impurities and water were removed, and then the product was dried under vacuum at 60 °C for 12 h to obtain brown Fe3O4@v-SiO2. 3) The above product was dispersed in a mixture of 60 mL ethanol and 0.06 mL concentrated hydrochloric acid and reacted at 60 °C for 3 h to remove CTAB and obtain Fe3O4@v-mSiO2. 4) Disperse 0.1 g Fe3O4@v-mSiO2 in a mixture of 128 ml ethanol and 36.0 ml distilled water. Then, add 2 ml KH570 and 40 ml NH3·H2O sequentially. React under ultrasonic and mechanical stirring conditions for 12 h. After the reaction is complete, separate the product, remove impurities and water, and then dry it under vacuum at 60℃ for 12 h to obtain surface-activated Fe3O4@v-mSiO2. 2； 5) Weigh 0.06 g of surface-activated Fe3O4@v-mSiO2 microspheres and disperse them in 80.0 mL of acetonitrile. Then add 8 g of AIBN and after complete dissolution, add 2 g of DMAA and 2 g of DMP in sequence. Heat the mixture to 90 °C at a rate of 1 °C per minute and continue to react at this temperature for 1 h. After the reaction is completed, separate the product, remove impurities and water, and then dry it in a vacuum environment at 60 °C for 12 h to obtain the functional mesoporous magnetic nanomaterial Fe3O4@v-mSiO2-P (DMAA-DMP).

4. A material capable of adsorbing uranium (U) in wastewater prepared by any of the methods described in claims 1 to 3. Its characteristics are Composed of a superparamagnetic Fe3O4 magnetic core and an ordered mesoporous SiO2 shell on the core surface, the synthesized magnetic mesoporous material has a specific surface area of ​​300-400 m². 2 / g.

5. The uranium-adsorbing material in wastewater according to claim 4, characterized in that: P=O and -NH2 groups were added to the mesopores of the shell.

6. The uranium-absorbing material in wastewater according to claim 5, characterized in that... The specific surface area of ​​the magnetic mesoporous material is 318 m². 2 / g.

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