Preparation method and application of graphene nanomicrosphere adsorption material
Patent Information
- Application Number
- CN202610884805.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-18
- Publication Date
- 2026-08-21
AI Technical Summary
[0004]石墨烯材料因具备超高的比表面积、表面化学可调性以及优异的机械性能成为高效吸附材料的有利候选者，但是由于放射性核废水中含有大量的硼酸，通常在强酸环境中石墨烯材料的稳定性低降低、并且石墨烯片层因为范德华力的作用可能会导致堆叠团聚，减少有效比表面积等因素使得吸附性能大大降低，因此亟待开发出一中新型的石墨烯吸附材料，在保证稳定性的同时，具备高效吸附放射性废水中的离子
1、本发明提供的一种石墨烯纳米微球吸附材料的制备方法，相对于其他方法，例如静电喷雾技术和模板法制备的石墨烯微球，不需要涉及到高电压等有危险性的仪器，同时也不需要添加模板剂，以及去除模板的实验步骤，大大降低了能量消耗及制备难度。
Smart Images
Figure CN122605487A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of graphene adsorption material preparation technology, specifically relating to a preparation method and application of graphene nanosphere adsorption material. Background Technology
[0002] Climate change severely threatens sustainable development, primarily due to excessive greenhouse gas emissions. my country has therefore set a "dual carbon" target, making energy transition a crucial path. Currently, traditional fossil fuel power generation accounts for too high a proportion, necessitating a shift to clean energy: vigorously developing new energy sources such as wind and solar power, constructing ultra-high-voltage smart grids, and supporting energy storage systems are essential to ensure power supply while achieving significant emission reductions. This is not only an inevitable choice to overcome environmental constraints but also a strategic opportunity to cultivate new economic growth. Nuclear energy occupies an important position in the energy structure and is a vital pillar energy source for achieving carbon peaking.
[0003] Nuclear wastewater mainly originates from tritium-containing wastewater generated during the normal operation of nuclear power plants and large amounts of water contaminated after nuclear accidents. Nuclear wastewater contains various radioactive substances, such as tritium, cesium, and strontium, which can cause severe damage to marine ecosystems. Current nuclear wastewater treatment primarily relies on three technical systems: physical treatment, chemical treatment, and biological treatment. However, these methods face multiple challenges in practical application: firstly, for radioactive nuclides with high solubility and small ionic radii, the removal efficiency of traditional treatment processes is generally limited, making deep purification difficult; secondly, chemical treatment methods rely on large amounts of precipitants and chelating agents, easily leading to the formation of secondary pollutants (such as heavy metal complexes and chemical sludge), and the consumption of reagents results in high costs; furthermore, biological treatment methods are limited by the tolerance and metabolic efficiency of microorganisms, making them unsuitable for complex environments such as high radiation and strong acidity. These overlapping technical bottlenecks make radioactive wastewater treatment an urgent industry problem to be solved.
[0004] Graphene is a promising candidate for high-efficiency adsorption materials due to its ultra-high specific surface area, tunable surface chemistry, and excellent mechanical properties. However, radioactive wastewater contains a large amount of boric acid, which reduces the stability of graphene materials in a strongly acidic environment. Furthermore, the van der Waals forces of graphene sheets may cause them to stack and aggregate, reducing the effective specific surface area and significantly lowering the adsorption performance. Therefore, there is an urgent need to develop a new type of graphene adsorption material that can efficiently adsorb ions from radioactive wastewater while ensuring stability. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing graphene nanosphere adsorption materials and their applications. This method uses crosslinking agents such as sodium poly(p-styrene)benzenesulfonate to functionalize and crosslink the surface of graphene to form a three-dimensional spherical structure. At the same time, the adsorption sites occupied by the functionalization can specifically bind to radioactive nuclide ions, which can significantly improve the adsorption capacity of graphene materials for radioactive nuclide ions. Furthermore, the three-dimensional spherical structure not only greatly increases the specific surface area and provides abundant active sites for adsorbing radioactive nuclides, but also selectively adsorbs radioactive ions in boron-containing nuclear wastewater, effectively improving adsorption stability and selectivity.
[0006] Technical solution to achieve the purpose of this invention: A method for preparing graphene nanosphere adsorbent materials includes: Step (1) Graphene oxide dispersion was synthesized using the modified Hummers method; Step (2) Take the graphene oxide dispersion from step (1) and dilute it. Add a crosslinking agent and stir until it is evenly dispersed. Then add ammonia solution for reduction. After reduction, filter and wash with pure water to obtain the reduced graphene oxide solution. Step (3) The reduced graphene oxide solution is redispersed, and after dispersion, it is cross-linked by microwave radiation and self-assembled to form a spherical structure. Then it is immediately frozen with liquid nitrogen to obtain frozen graphene. Step (4) Transfer the frozen graphene to a freeze dryer for freeze drying to obtain graphene nanospheres.
[0007] Further, step (1) includes: Step (1.1) After grinding the natural graphite powder, add it to a mixed solution A containing potassium persulfate, phosphorus pentoxide and concentrated sulfuric acid that has been ultrasonically treated for pre-oxidation. After cooling, add pure water to dilute and let stand overnight. Filter the precipitate into a solid and then dry it. Step (1.2) After grinding the dried solid, add concentrated sulfuric acid, then slowly add potassium permanganate and stir for the first time; then slowly add pure water dropwise and heat up to stir for the second time; then transfer to a beaker and stir for the third time, adding pure water while stirring, and immediately adding hydrogen peroxide solution after adding pure water, continue stirring, and let stand overnight. Step (1.3) Remove the supernatant, add pure water to dilute, perform the first centrifugation, and collect the precipitate; wash the precipitate with hydrochloric acid, perform the second centrifugation, and collect the precipitate; add pure water to dilute the precipitate again, perform the third centrifugation, and finally collect the precipitate graphene oxide, dilute with pure water to make up the volume, sonicate and stir to obtain graphene oxide dispersion.
[0008] Further, in step (2), the concentration of the diluted graphene oxide dispersion is 0.2-5 mg / mL; the molar ratio of graphene oxide to crosslinking agent is 1:1 to 1:10.
[0009] Furthermore, in step (2), the volume ratio of ammonia solution to graphene oxide dispersion is 10:1; the reduction temperature is 80-90℃ and the time is 1-4h.
[0010] Furthermore, in step (2), the crosslinking agent is at least one of sodium poly(p-styrene sulfonate), benzenesulfonic acid, sodium sulfate, and sulfonamide.
[0011] Furthermore, in step (3), the concentration of the redispersed graphene oxide solution is 0.5-2 mg / mL.
[0012] Furthermore, in step (3), the microwave radiation time is 5-15 min; the liquid nitrogen freezing time is 5-15 min.
[0013] Furthermore, in step (4), the freeze-drying temperature is -48°C, the pressure is -0.1 MPa, and the time is 72h.
[0014] Furthermore, in step (4), the particle size of the graphene nanospheres is 400-500 nm.
[0015] Application of a graphene nanosphere adsorption material in the adsorption of radioactive nuclide ions.
[0016] The beneficial technical effects of this invention are as follows: 1. The present invention provides a method for preparing graphene nanosphere adsorbent materials. Compared with other methods, such as graphene microspheres prepared by electrostatic spraying technology and template method, it does not require dangerous instruments such as high voltage, nor does it require the addition of template agents or experimental steps for template removal, which greatly reduces energy consumption and preparation difficulty.
[0017] 2. The present invention provides a method for preparing graphene nanosphere adsorbent materials. The graphene nanospheres prepared by using crosslinking agents such as sodium poly(p-styrene)benzenesulfonate have higher adsorption performance and better selectivity.
[0018] 3. The present invention provides a method for preparing graphene nanosphere adsorption materials. The preparation steps are simple, requiring no complex equipment or harsh conditions, with no secondary pollution and no need to use large amounts of toxic and difficult-to-recover organic solvents.
[0019] 4. The graphene nanosphere adsorbent material prepared by the method provided by the present invention can effectively resist the interference of impurity ions and selectively adsorb radionuclides in nuclear waste liquid. Attached Figure Description
[0020] Figure 1 This is a scanning electron microscope image of the graphene nanosphere adsorption material prepared in Example 1 of the present invention; Figure 2 The graph shows the maximum adsorption capacity of the graphene nanosphere adsorption material prepared in Example 1 of this invention for radionuclide ions in a simulated solution. Figure 3 This is a graph showing the adsorption rate of boric acid substances in a simulated solution by the graphene nanosphere adsorbent material prepared in Example 1 of the present invention. Figure 4 The graph shows the maximum adsorption rate of the graphene nanosphere adsorbent material prepared in Example 2 of this invention for radionuclides in boron-containing radioactive waste liquid. Figure 5 The graph shows the adsorption rate of boric acid substances by the graphene nanosphere adsorbent material prepared in Example 2 of this invention in boron-containing radioactive waste liquid. Figure 6 The graph shows the maximum adsorption capacity of the graphene nanosphere adsorption material prepared in Example 3 of this invention for radionuclides in boron-containing radioactive simulated waste liquid at different pH values. Figure 7 The graphene nanosphere adsorbent material prepared in Example 3 of this invention contains impurity ions (such as Na+). + Fe 3+ Diagram showing the maximum adsorption capacity of radionuclides in boron-containing radioactive simulated waste liquid under interference conditions. Detailed Implementation
[0021] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.
[0022] This invention provides a method for preparing graphene nanosphere adsorbent materials. Using graphite as the raw material, a graphene oxide dispersion is synthesized using a modified Hummers method. Graphene oxide and sodium poly(p-styrene sulfonate) are solvated, and by utilizing the condensation reaction between the functional groups of the reactants, excess functional groups are removed using microwave radiation technology, while the graphene microspheres undergo rapid self-assembly. This yields graphene oxide nanospheres with high adsorption performance, suitable for the selective adsorption of nuclides in boron-containing radioactive waste. The specific steps include: Step (1) Graphene oxide dispersion was synthesized using the modified Hummers method; Step (1.1) After grinding the natural graphite powder, add it to a mixed solution A containing potassium persulfate, phosphorus pentoxide and concentrated sulfuric acid that has been ultrasonically treated for pre-oxidation. After cooling, add pure water to dilute and let stand overnight. Filter the precipitate into a solid and then dry it. Step (1.2) After grinding the solid dried in step (1.1), add concentrated sulfuric acid, then slowly add potassium permanganate and stir for the first time; then slowly add pure water dropwise and heat up to stir for the second time; then transfer to a beaker and stir for the third time, while adding pure water, add hydrogen peroxide solution immediately after adding pure water, continue stirring, and let stand overnight. Step (1.3): Remove the supernatant, dilute with pure water, centrifuge for the first time, and collect the precipitate; wash the precipitate with hydrochloric acid, centrifuge for the second time, and collect the precipitate; dilute the precipitate with pure water again, centrifuge for the third time, and finally collect the precipitate graphene oxide, dilute with pure water to a fixed volume, sonicate and stir to obtain a graphene oxide dispersion with a concentration of 5 mg / mL and an oxygen content of 28.2 wt%.
[0023] Step (2) Take the graphene oxide dispersion from step (1) and dilute it. Add a crosslinking agent and stir until it is evenly dispersed. Then add ammonia solution for reduction. After reduction, filter and wash with pure water to obtain the reduced graphene oxide solution. In step (2), the concentration of the diluted graphene oxide dispersion is 0.2-5 mg / mL; the molar ratio of graphene oxide to crosslinking agent is 1:1 to 1:10 (the relative molecular mass of graphene oxide is generally expressed as 12 g / mol based on the relative molecular mass of C); the concentration of the ammonia solution is 25-28 wt%, and the volume ratio of the ammonia solution to the graphene oxide dispersion is 10:1; the reduction temperature is 80-90℃, and the time is 1-4 h; the crosslinking agent is at least one of sodium poly(p-styrene sulfonate), benzenesulfonic acid, sodium sulfate, and sulfonamide containing sulfonic acid groups.
[0024] Step (3) The reduced graphene oxide solution is redispersed with pure water, and after dispersion, it is cross-linked by microwave radiation and self-assembled to form a spherical structure. Then it is immediately frozen with liquid nitrogen to obtain frozen graphene. In step (3), the concentration of the redispersed graphene oxide solution is 0.5-2 mg / mL; the microwave irradiation time is 5-15 min; the liquid nitrogen freezing temperature is -196℃ and the time is 5-15 min.
[0025] Step (4) Transfer the frozen graphene to a freeze dryer for freeze drying to obtain graphene nanospheres.
[0026] In step (4), the freeze-drying temperature is -48℃, the pressure is -0.1 MPa, and the time is 72h; the particle size of the graphene nanospheres is 400-500 nm.
[0027] Example 1 This embodiment provides a method for preparing graphene nanosphere adsorption materials, specifically including the following steps: Step (1) Graphene oxide dispersion was synthesized using the modified Hummers method; Step (1.1) Grind 3 g of natural graphite powder into a uniformly dispersed powder, then add it to a mixed solution A containing 2.5 g potassium persulfate, 2.5 g phosphorus pentoxide, and 12 mL concentrated sulfuric acid (18 mol / L), which has been ultrasonically treated. Pre-oxidize the solution at 80°C for 4.5 h. After cooling to room temperature, dilute with 500 mL of pure water and let stand overnight. Discard the supernatant, and filter the precipitate into a solid using a vacuum filtration device. Then, dry the solid in a vacuum drying oven at 60°C. o Dry at C for 24 hours.
[0028] Step (1.2) Grind the dried sample, add 120 mL of concentrated sulfuric acid (18 mol / L), then slowly add 15 g of potassium permanganate, keeping the temperature below 6℃ throughout the process, and then stir for the first time at 35℃ for 2 h; slowly add 250 mL of pure water, keeping the temperature below 13℃, and then stir for the second time at room temperature for 2 h; then transfer to a 2 L beaker and stir for the third time at room temperature, adding 700 mL of pure water while stirring, and immediately after adding the pure water, add 20 mL of 30% hydrogen peroxide, continue stirring for 0.5 h, and let stand overnight.
[0029] Step (1.3): Remove the supernatant, dilute with 1 L of pure water, centrifuge at 8000 rpm for 10 min, discard the supernatant, and collect the precipitate. Dilute and wash the precipitate with a 1:10 dilute hydrochloric acid solution (12 mol / L concentration), centrifuge at 8000 rpm for 10 min, discard the supernatant, and collect the precipitate. Dilute with another 1 L of pure water, centrifuge at 10000 rpm for 10 min, discard the supernatant, and finally collect the precipitate of graphene oxide. Dilute with 1 L of pure water to a final volume, sonicate for 0.5 h, and stir for later use to obtain a graphene oxide dispersion with a concentration of 5 mg / mL.
[0030] Step (2): Take 5 mL of the above graphene oxide dispersion and dilute it with pure water to a concentration of 0.2 mg / mL. Add 0.17 mmol of sodium poly(p-styrene sulfonate) and stir thoroughly until uniformly dispersed to obtain mixed solution B. Slowly heat mixed solution B to 80℃, add 50 mL of ammonia solution, and reduce for 2 h to obtain a reduced solution. Filter and wash the reduced solution with pure water at least 3 times to remove residual ammonia to obtain the reduced graphene oxide solution.
[0031] Step (3): The reduced graphene oxide solution was redispersed with pure water to obtain a dispersion with a concentration of 0.5 mg / mL. The dispersion was then subjected to microwave irradiation for 5 min to crosslink and self-assemble into spherical structures. It was then immediately frozen in liquid nitrogen at a temperature of -196°C. o At temperature C, and a time of 10 minutes, frozen graphene was obtained.
[0032] Step (4) The frozen graphene was quickly transferred to a freeze dryer and freeze-dried at -48℃ and -0.1 MPa for 72 h to obtain graphene nanospheres with a particle size of 400 nm.
[0033] Example 2 This embodiment provides a method for preparing graphene nanosphere adsorption materials, specifically including the following steps: Step (1) Graphene oxide dispersion was synthesized using the modified Hummers method; Step (1.1) Grind 3 g of natural graphite powder into a uniformly dispersed powder, then add it to a mixed solution A containing 2.5 g potassium persulfate, 2.5 g phosphorus pentoxide, and 12 mL concentrated sulfuric acid (18 mol / L), which has been ultrasonically treated. Pre-oxidize the solution at 85 °C for 4.5 h. After cooling to room temperature, dilute with 500 mL of pure water and let stand overnight. Discard the supernatant, and filter the precipitate into a solid using a vacuum filtration device. Then, dry the solid in a vacuum drying oven at 60 °C. o Dry at C for 24 hours.
[0034] Step (1.2) Grind the dried sample, add 120 mL of concentrated sulfuric acid (18 mol / L), then slowly add 15 g of potassium permanganate, keeping the temperature below 6℃ throughout the process, and then stir for the first time at 35℃ for 2 h; slowly add 250 mL of pure water, keeping the temperature below 13℃, and then stir for the second time at room temperature for 2 h; then transfer to a 2 L beaker and stir for the third time at room temperature, adding 700 mL of pure water while stirring, and immediately after adding the pure water, add 20 mL of 30% hydrogen peroxide, continue stirring for 0.5 h, and let stand overnight.
[0035] Step (1.3): Remove the supernatant, dilute with 1 L of pure water, centrifuge at 8000 rpm for 10 min, discard the supernatant, and collect the precipitate. Dilute and wash the precipitate with a 1:10 dilute hydrochloric acid solution (12 mol / L concentration), centrifuge at 8000 rpm for 10 min, discard the supernatant, and collect the precipitate. Dilute with another 1 L of pure water, centrifuge at 10000 rpm for 10 min, discard the supernatant, and finally collect the precipitate of graphene oxide. Dilute with 1 L of pure water to a final volume, sonicate for 0.5 h, and stir for later use to obtain a graphene oxide dispersion with a concentration of 5 mg / mL.
[0036] Step (2): Take 5 mL of the above graphene oxide dispersion and dilute it with pure water to a concentration of 0.2 mg / mL. Add 0.17 mmol of sodium poly(p-styrene sulfonate) and stir thoroughly until uniformly dispersed to obtain mixed solution B. Slowly heat mixed solution B to 85 °C, add 50 mL of ammonia solution, and reduce for 1 h to obtain a reduced solution. Filter and wash the reduced solution with pure water at least 3 times to remove residual ammonia to obtain the reduced graphene oxide solution.
[0037] Step (3): The reduced graphene oxide solution was redispersed with pure water to obtain a dispersion with a concentration of 1 mg / mL. The dispersion was then subjected to microwave irradiation for 10 min to crosslink and self-assemble into spherical structures. It was then immediately frozen in liquid nitrogen at a temperature of -196°C. o At temperature C, and a time of 10 minutes, frozen graphene was obtained.
[0038] Step (4) The frozen graphene was quickly transferred to a freeze dryer and freeze-dried at -48℃ and -0.1 MPa for 72 h to obtain graphene nanospheres with a particle size of 400 nm.
[0039] Example 3 This embodiment provides a method for preparing graphene nanosphere adsorption materials, specifically including the following steps: Step (1) Graphene oxide dispersion was synthesized using the modified Hummers method; Step (1.1) Grind 3 g of natural graphite powder into a uniformly dispersed powder, then add it to a mixed solution A containing 2.5 g potassium persulfate, 2.5 g phosphorus pentoxide, and 12 mL concentrated sulfuric acid (18 mol / L), which has been ultrasonically treated. Pre-oxidize the solution at 80°C for 4.5 h. After cooling to room temperature, dilute with 500 mL of pure water and let stand overnight. Discard the supernatant, and filter the precipitate into a solid using a vacuum filtration device. Then, dry the solid in a vacuum drying oven at 60°C. oDry at C for 24 hours.
[0040] Step (1.2) Grind the dried sample, add 120 mL of concentrated sulfuric acid (18 mol / L), then slowly add 15 g of potassium permanganate, keeping the temperature below 6℃ throughout the process, and then stir for the first time at 35℃ for 2 h; slowly add 250 mL of pure water, keeping the temperature below 13℃, and then stir for the second time at room temperature for 2 h; then transfer to a 2 L beaker and stir for the third time at room temperature, adding 700 mL of pure water while stirring, and immediately after adding the pure water, add 20 mL of 30% hydrogen peroxide, continue stirring for 0.5 h, and let stand overnight.
[0041] Step (1.3): Remove the supernatant, dilute with 1 L of pure water, centrifuge at 8000 rpm for 10 min, discard the supernatant, and collect the precipitate. Dilute and wash the precipitate with a 1:10 dilute hydrochloric acid solution (12 mol / L concentration), centrifuge at 8000 rpm for 10 min, discard the supernatant, and collect the precipitate. Dilute with another 1 L of pure water, centrifuge at 10000 rpm for 10 min, discard the supernatant, and finally collect the precipitate of graphene oxide. Dilute with 1 L of pure water to a final volume, sonicate for 0.5 h, and stir for later use to obtain a graphene oxide dispersion with a concentration of 5 mg / mL.
[0042] Step (2): Take 5 mL of the above graphene oxide dispersion and dilute it with pure water to a concentration of 0.2 mg / mL. Add 0.17 mmol of sodium poly(p-styrene sulfonate) and stir thoroughly until uniformly dispersed to obtain mixed solution B. Slowly heat mixed solution B to 90 °C, add 50 mL of ammonia solution, and reduce for 4 h to obtain a reduced solution. Filter and wash the reduced solution with pure water at least three times to remove residual ammonia, obtaining the reduced graphene oxide solution.
[0043] Step (3): The reduced graphene oxide solution was redispersed with pure water to obtain a dispersion with a concentration of 2 mg / mL. The dispersion was then subjected to microwave irradiation for 15 min to crosslink and self-assemble into spherical structures. It was then immediately frozen in liquid nitrogen at a temperature of -196°C. o At temperature C, and a time of 15 minutes, frozen graphene was obtained.
[0044] Step (4) The frozen graphene was quickly transferred to a freeze dryer and freeze-dried at -48℃ and -0.1 MPa for 72 h to obtain graphene nanospheres with a particle size of 400 nm.
[0045] Example 1 Scanning electron microscope (SEM) images of the graphene nanosphere adsorbent material prepared in Example 1 are shown below. Figure 1 As shown. By Figure 1 It can be seen that the size of the prepared graphene nanospheres is distributed in the range of 400-500 nm, indicating that the cross-linking process successfully prepared microspherical graphene adsorbent materials.
[0046] Example 2 50 mL simulated solutions were prepared, each containing 30 mg / L of nuclide ions (cesium, cobalt, silver, and strontium) and 1000 mg / L of boric acid. 5 mg of the graphene nanosphere adsorbent material prepared in Example 1 was added to each solution. Adsorption was performed in an adsorption column at 25°C using a circulating pump for 120 min. The changes in nuclide ion concentrations before and after adsorption were measured, and the maximum adsorption capacity and adsorption rate of boric acid in the solution were calculated. The results are as follows: Figure 2-3 As shown.
[0047] Depend on Figure 2 It can be seen that the maximum adsorption capacities of the graphene nanospheres prepared in Example 1 for typical nuclide ions cesium, cobalt, silver, and strontium are 195.4 mg / g, 193.5 mg / g, 176.2 mg / g, and 205.6 mg / g, respectively. The differences in adsorption capacity for each ion may be related to their chemical valence state. The main reason for the high adsorption capacity of the graphene nanospheres for these nuclide ions is that the surface of the graphene nanospheres contains abundant adsorption sites, which can adsorb a large number of metal ions in the system. At the same time, the sulfonic acid functional groups can form stable chemical bonds with radioactive nuclide ions, thereby forming stable compounds and increasing the adsorption capacity. Figure 3 As shown, in systems with different radioactive nuclide ions, the adsorption rate of boric acid by graphene nanospheres is less than 5%. This is because the sites on the surface of graphene nanospheres used for adsorbing boric acid are replaced by sulfonic acid groups, resulting in an extremely low boric acid adsorption rate.
[0048] Example 3 50 mL solutions containing radionuclide ions (cesium, cobalt, silver, and strontium), with a radioactivity of 50 Bq / L and a boric acid content of 1000 mg / L were prepared. 5 mg of the graphene nanosphere adsorbent material prepared in Example 2 was added to each solution. Adsorption was performed in an adsorption column at 25°C using a circulating pump for 120 min. The changes in the concentration of radionuclide ions in the solution before and after adsorption were measured, and the maximum removal rate and the adsorption rate of boric acid in the solution were calculated. The results are as follows: Figure 4-5 As shown.
[0049] Depend on Figure 4It can be seen that the maximum adsorption rates of the graphene nanospheres prepared in Example 2 for typical nuclide ions cesium, cobalt, silver, and strontium were 95.4%, 95.9%, 96.8%, and 97.5%, respectively. The differences in adsorption rates for each ion may be related to their chemical valence states. The main reason for the high adsorption rates of the graphene nanospheres for these nuclide ions is that the surface of the graphene nanospheres contains abundant adsorption sites, which can adsorb a large number of metal ions in the system. At the same time, the sulfonic acid functional groups can form stable chemical bonds with radioactive nuclide ions, thereby forming stable compounds and enhancing the removal effect. Figure 5 As shown, in systems with different radioactive nuclide ions, the adsorption rate of boric acid by graphene nanospheres is less than 5%. This is because the sites on the surface of graphene nanospheres used for adsorbing boric acid are replaced by sulfonic acid groups, resulting in an extremely low boric acid adsorption rate.
[0050] Example of effect 4 Prepare 50 mL simulated solutions containing 30 mg / L of nuclide ions (cesium, cobalt, silver, and strontium). Adjust the pH of the simulated solutions to 1, 3, 5, and 7, respectively. Add 5 mg of the graphene nanosphere adsorbent material prepared in Example 3 to each solution. Adsorb the materials in an adsorption column at 25°C using a circulating pump for 120 min. Test the change in the concentration of nuclide ions in the solution before and after adsorption, and calculate the maximum adsorption capacity. The results are as follows: Figure 6 As shown.
[0051] Depend on Figure 6 It can be seen that the maximum adsorption capacities of the graphene nanosphere adsorbent material prepared in Example 3 for typical nuclide ions (cesium, cobalt, silver and strontium) are 203.2 mg / g, 205.8 mg / g, 196.7 mg / g and 209.6 mg / g, respectively. The difference in adsorption capacity of each ion may be related to its chemical valence state. The main reason why the graphene nanosphere adsorbent material has a high adsorption capacity for the above-mentioned nuclide ions is that the surface of the graphene nanosphere contains abundant adsorption sites, which can adsorb a large number of metal ions in the system. At the same time, the sulfonic acid functional group can form stable chemical bonds with radioactive nuclide ions, thereby forming stable compounds and increasing the adsorption capacity.
[0052] Example 5 Prepare 50 mL solutions containing nuclide ions (cesium, cobalt, silver, and strontium) at a concentration of 30 mg / L, boric acid at a concentration of 1000 mg / L, and interfering ion: Na+. + The content is 20 mg / L, Fe 3+A simulated solution with a concentration of 50 mg / L was prepared by adding 5 mg of the graphene nanosphere adsorbent material prepared in Example 3 to each solution. Adsorption was carried out in an adsorption column at 25°C using a circulating pump for 120 min. The concentration change of radionuclide ions in the solution before and after adsorption was measured, and the maximum adsorption capacity was calculated. The results are as follows: Figure 7 As shown.
[0053] Depend on Figure 7 It can be seen that the maximum adsorption capacities of the graphene nanosphere adsorbent material prepared in Example 3 for typical nuclide ions (cesium, cobalt, silver and strontium) are 223.8 mg / g, 224.5 mg / g, 199.7 mg / g and 253.9 mg / g, respectively. The difference in adsorption capacity of each ion may be related to its chemical valence state. The main reason why the graphene nanosphere adsorbent material has a high adsorption capacity for the above-mentioned nuclide ions is that the surface of the graphene nanosphere contains abundant adsorption sites, which can selectively adsorb a large number of metal ions in the system. At the same time, the sulfonic acid functional group can form stable chemical bonds with radioactive nuclide ions, thereby forming stable compounds and increasing the adsorption capacity.
[0054] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. All contents not described in detail in the present invention can be derived from existing technologies.
Claims
1. A method for preparing graphene nanosphere adsorbent materials, characterized in that, include: Step (1) Graphene oxide dispersion was synthesized using the modified Hummers method; Step (2) Take the graphene oxide dispersion from step (1) and dilute it. Add a crosslinking agent and stir until it is evenly dispersed. Then add ammonia solution for reduction. After reduction, filter and wash with pure water to obtain the reduced graphene oxide solution. Step (3) The reduced graphene oxide solution is redispersed, and after dispersion, it is cross-linked by microwave radiation and self-assembled to form a spherical structure. Then it is immediately frozen with liquid nitrogen to obtain frozen graphene. Step (4) Transfer the frozen graphene to a freeze dryer for freeze drying to obtain graphene nanospheres.
2. The method for preparing a graphene nanosphere adsorbent material according to claim 1, characterized in that, Step (1) includes: Step (1.1) After grinding the natural graphite powder, add it to a mixed solution A containing potassium persulfate, phosphorus pentoxide and concentrated sulfuric acid that has been ultrasonically treated for pre-oxidation. After cooling, add pure water to dilute and let stand overnight. Filter the precipitate into a solid and then dry it. Step (1.2) After grinding the dried solid, add concentrated sulfuric acid, then slowly add potassium permanganate and stir for the first time; then slowly add pure water dropwise and heat up to stir for the second time; then transfer to a beaker and stir for the third time, adding pure water while stirring, and immediately adding hydrogen peroxide solution after adding pure water, continue stirring, and let stand overnight. Step (1.3) Remove the supernatant, add pure water to dilute, perform the first centrifugation, and collect the precipitate; wash the precipitate with hydrochloric acid, perform the second centrifugation, and collect the precipitate; add pure water to dilute the precipitate again, perform the third centrifugation, and finally collect the precipitate graphene oxide, dilute with pure water to make up the volume, sonicate and stir to obtain graphene oxide dispersion.
3. The method for preparing a graphene nanosphere adsorbent material according to claim 1, characterized in that, In step (2), the concentration of the diluted graphene oxide dispersion is 0.2-5 mg / mL; the molar ratio of graphene oxide to crosslinking agent is 1:1 to 1:
10.
4. The method for preparing a graphene nanosphere adsorbent material according to claim 1, characterized in that, In step (2), the volume ratio of ammonia solution to graphene oxide dispersion is 10:1; the reduction temperature is 80-90℃ and the time is 1-4h.
5. The method for preparing a graphene nanosphere adsorbent material according to claim 1, characterized in that, In step (2), the crosslinking agent is at least one of sodium poly(p-styrene sulfonate), benzenesulfonic acid, sodium sulfate, and sulfonamide.
6. The method for preparing a graphene nanosphere adsorbent material according to claim 1, characterized in that, In step (3), the concentration of the redispersed graphene oxide solution is 0.5-2 mg / mL.
7. The method for preparing a graphene nanosphere adsorbent material according to claim 1, characterized in that, In step (3), the microwave radiation time is 5-15 min; the liquid nitrogen freezing time is 5-15 min.
8. The method for preparing a graphene nanosphere adsorbent material according to claim 1, characterized in that, In step (4), the freeze-drying temperature is -48℃, the pressure is -0.1 MPa, and the time is 72h.
9. The method for preparing a graphene nanosphere adsorbent material according to claim 1, characterized in that, In step (4), the particle size of the graphene nanospheres is 400-500 nm.
10. The application of graphene nanosphere adsorbent materials prepared by the preparation method according to any one of claims 1-9 in the adsorption of radioactive nuclide ions.