Carbon-based material, preparation method and application thereof, and method for purifying wastewater containing uranium

Abstract

The application provides a carbon-based material and a preparation method and application thereof, and a uranium-containing wastewater purification method, and relates to the technical field of water treatment.The carbon-based material comprises a carbon base and nano zero-valent iron particles filled in the pores of the carbon base and loaded on the surface of the carbon base.By doping the nano zero-valent iron in the carbon base and loading the nano zero-valent iron particles on the surface of the carbon base, the carbon-based material can increase the diffusion of the nano zero-valent iron particles, effectively prevent the defects of agglomeration and oxidation of the nano zero-valent iron particles, and improve the stability of the nano zero-valent iron particles in the carbon-based material.The carbon-based material is applied to the purification of uranium-containing wastewater, has excellent removal effect on uranium ions, and has no toxicity, corrosiveness and radioactivity in the recycling process of the carbon-based material, so that secondary pollution is avoided.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a carbon-based material, its preparation method and application, and a method for purifying uranium-containing wastewater. Background Technology

[0002] Uranium is the primary energy source for nuclear energy development, but the rapid development of the nuclear industry has generated a large amount of uranium-containing wastewater, characterized by complex composition, low concentration, high toxicity, and radioactivity. Currently, commonly used methods for treating uranium-containing wastewater include chemical precipitation, coagulation, photocatalysis, chemical reduction, ion exchange, biological methods, and adsorption. Among these, adsorption has attracted significant attention due to its simple operation, rapid adsorption efficiency, high uranium selectivity, and large adsorption capacity. In recent years, various materials for uranium adsorption have seen rapid development, such as activated carbon, nano-zero-valent iron, mesoporous silica, metal-organic frameworks, and covalent organic frameworks.

[0003] In recent years, core-shell structured nano-zero valent iron (nZVI) has become a major material for adsorbing heavy metals such as U, Cd, and Ni from wastewater due to its high efficiency, large capacity, and strong activity. However, when used as an adsorbent, nZVI particles are prone to aggregation and oxidation, resulting in poor stability. Summary of the Invention

[0004] The purpose of this invention is to provide a carbon-based material, its preparation method and application, and a method for purifying uranium-containing wastewater. The carbon-based material provided by this invention is not prone to agglomeration and oxidation, and has excellent stability.

[0005] To achieve the objectives of this invention, the following technical solutions are provided:

[0006] A carbon-based material includes a carbon matrix and nano-zero-valent iron particles filling the pores of the carbon matrix and loaded on the surface of the carbon matrix.

[0007] Preferably, the mass content of nano-zero-valent iron particles in the carbon-based material is 4-6%.

[0008] Preferably, the particle size of the nano-zero valent iron particles is 200–300 nm.

[0009] The present invention also provides a method for preparing the carbon-based material described in the above technical solution, comprising the following steps:

[0010] Potassium ferricyanide, glucose, pH adjuster and water are mixed to obtain the precursor solution;

[0011] The precursor liquid and carbon material are mixed and subjected to a hydrothermal reaction to obtain a carbon-based material precursor.

[0012] The carbon-based material precursor is carbonized to obtain the carbon-based material.

[0013] Preferably, the carbon material is composed of carbon fibers; the mass ratio of the carbon material, potassium ferricyanide and glucose is 1:2 to 3:1.

[0014] Preferably, the hydrothermal reaction is carried out at a temperature of 110–130°C for 4–6 hours.

[0015] Preferably, the carbonization temperature is 700–1000°C and the time is 6–8 hours.

[0016] The present invention also provides the application of the carbon-based materials described in the above technical solutions or the carbon-based materials prepared by the preparation methods described in the above technical solutions in the purification of uranium-containing wastewater.

[0017] The present invention also provides a method for purifying uranium-containing wastewater, comprising the following steps:

[0018] The carbon-based material is mixed with uranium-containing wastewater for adsorption; the carbon-based material is the carbon-based material described in the above technical solution or the carbon-based material prepared by the preparation method described in the above technical solution.

[0019] Preferably, the solid-liquid ratio of the carbon-based material and the uranium-containing wastewater is 1.2 to 1.6 g / L.

[0020] This invention provides a carbon-based material comprising a carbon matrix and nano-zero-valent iron particles filling the pores of the carbon matrix and loaded on the surface of the carbon matrix. By doping the carbon matrix with nano-zero-valent iron and loading the nano-zero-valent iron particles onto the carbon matrix surface, this invention enhances the diffusion of the nano-zero-valent iron particles, effectively preventing their aggregation. Simultaneously, the carbon encapsulation mitigates the oxidation defects of the nano-zero-valent iron, improving the stability of the nano-zero-valent iron particles in the carbon-based material. Furthermore, the nano-zero-valent iron particles filling the pores of the carbon matrix have the function of adsorbing and reducing uranium.

[0021] The carbon-based material provided by this invention is applied to the purification of uranium-containing wastewater, demonstrating excellent removal efficiency for uranium ions. As shown in the results of the embodiments of this invention, the removal rate of uranium-containing wastewater with a concentration of 5–250 mg / L can reach over 90% within 2–6 hours, proving the excellent adsorption performance of the carbon-based material provided by this invention. Furthermore, the carbon-based material of this invention is non-toxic, non-corrosive, and non-radioactive during recycling, and will not cause secondary pollution. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 The images are SEM images of the carbon-based material precursors prepared in Examples 1-4, magnified 500 times.

[0024] Figure 2 The images are SEM images of the carbon-based material precursors prepared in Examples 1-4, magnified 100,000 times.

[0025] Figure 3 The XRD patterns of the carbon-based material precursors prepared in Examples 1-4 are shown below.

[0026] Figure 4 The image shows the SEM image of the carbon-based material prepared in Example 1.

[0027] Figure 5 The image shows the SEM image of the carbon-based material prepared in Example 2.

[0028] Figure 6 The image shows the SEM image of the carbon-based material prepared in Example 3.

[0029] Figure 7 The image shows the SEM image of the carbon-based material prepared in Example 4.

[0030] Figure 8 The XRD patterns of the carbon-based materials and carbon substrates prepared in Examples 1-4 are shown below.

[0031] Figure 9 XPS spectra of the carbon-based materials prepared in Examples 1-4;

[0032] Figure 10 The high-resolution XPS spectrum of Fe 2p for the carbon-based material prepared in Example 2;

[0033] Figure 11 Adsorption effect of carbon materials and carbon-based materials prepared in Examples 1-4 on aqueous solutions containing uranium ions;

[0034] Figure 12 The XPS full spectrum of the carbon-based material prepared in Example 2 before and after adsorption of uranium ions;

[0035] Figure 13 High-resolution U4f spectra of the carbon-based material prepared in Example 2 before and after adsorption of uranium ions;

[0036] Figure 14The XRD patterns of the carbon-based material prepared in Example 2 before and after adsorption of uranium ions are shown.

[0037] Figure 15 The adsorption effect of the carbon-based material prepared in Example 2 on uranium ions under different pH conditions is shown in the figure.

[0038] Figure 16 The graph shows the adsorption effect of the carbon-based material prepared in Example 2 on uranium ions at different adsorption temperatures;

[0039] Figure 17 The image shows the adsorption effect of the carbon-based material prepared in Example 2 on uranium ions of different concentrations.

[0040] Figure 18 The graph shows the adsorption effect of the carbon-based material described in Example 2 on uranium ions under different cation conditions;

[0041] Figure 19 The graph shows the adsorption effect of the carbon-based material described in Example 2 on uranium ions under different anion conditions;

[0042] Figure 20 The graph shows the test results of the carbon-based material prepared in Example 2 for extracting uranium from seawater.

[0043] Figure 21 The graph shows the adsorption effect of the carbon-based material prepared in Example 2 on uranium ions after three cycles of testing. Detailed Implementation

[0044] The present invention provides a carbon-based material comprising a carbon matrix and nano-zero-valent iron particles filling the pores of the carbon matrix and loaded on the surface of the carbon matrix.

[0045] In this invention, the mass content of nano-zero-valent iron particles in the carbon-based material is preferably 4-6%, more preferably 5%.

[0046] In this invention, the particle size of the nano-zero-valent iron particles is preferably 200–300 nm, more preferably 200–250 nm. In this invention, the nano-zero-valent iron particles have the function of adsorbing and reducing uranium.

[0047] The present invention also provides a method for preparing the carbon-based material described in the above technical solution, comprising the following steps:

[0048] Potassium ferricyanide, glucose, pH adjuster and water are mixed to obtain the precursor solution;

[0049] The precursor liquid and carbon material are mixed and subjected to a hydrothermal reaction to obtain a carbon-based material precursor.

[0050] The carbon-based material precursor is carbonized to obtain the carbon-based material.

[0051] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0052] This invention involves mixing potassium ferricyanide, glucose, a pH adjuster, and water to obtain a precursor solution. In this invention, the mass concentration of potassium ferricyanide in the precursor solution is preferably 20–24 g / L, more preferably 22–23 g / L. In this invention, the mass concentration of glucose in the precursor solution is preferably 8–10 g / L, more preferably 8.33–9 g / L.

[0053] In this invention, the pH adjuster is preferably one of concentrated hydrochloric acid, dilute hydrochloric acid, and dilute nitric acid, more preferably concentrated hydrochloric acid. In this invention, the mass content of the concentrated hydrochloric acid is preferably 36% to 38%, more preferably 37%. This invention does not have a particular limitation on the amount of pH adjuster used; it is sufficient to adjust the pH of the precursor solution to 1 to 2.

[0054] In this invention, the water is preferably ultrapure water.

[0055] In this invention, the potassium ferricyanide, glucose, pH adjuster and water are preferably mixed by stirring, and the stirring time is preferably 5 to 30 minutes, more preferably 5 to 10 minutes; the stirring rate is preferably 600 to 700 r / min, more preferably 650 r / min.

[0056] After obtaining the precursor liquid, the present invention mixes the precursor liquid with carbon material and performs a hydrothermal reaction to obtain a carbon-based material precursor. In the present invention, the carbon material is preferably composed of carbon fibers, and specifically, it can be one of a carbon felt substrate, carbon cloth, and carbon sheet composed of carbon fibers, more preferably a carbon felt substrate. In the present invention, the length of the carbon felt substrate is preferably 30–100 mm, more preferably 40–60 mm; the width is preferably 5–50 mm, more preferably 10–30 mm; and the thickness is preferably 2–5 mm, more preferably 3–4 mm. In the present invention, the carbon material has the functions of increasing the diffusion of nano-zero valent iron, slowing down the oxidation of nano-zero valent iron, and providing stable support.

[0057] In this invention, the mass ratio of the carbon material, potassium ferricyanide and glucose is preferably 1:2 to 3:1, and more preferably 1:2.64:1.

[0058] In this invention, the temperature of the hydrothermal reaction is preferably 110–130°C, more preferably 120°C; the time of the hydrothermal reaction is preferably 4–6 hours, more preferably 4 hours. In this invention, a portion of [Fe(CN)6] is involved in the hydrothermal reaction. 3- Fe decomposes under the action of HCl. 3+ The other part is [Fe(CN)6].3- Glucose (C6H) 12 O6) is reduced to [Fe(CN)6] 4- The Fe produced by the above reaction is then precipitated. 3+ and [Fe(CN)6] 4- Combining these elements allows for the in-situ generation of Prussian blue (Fe2+) on carbon materials. III 4[Fe II (CN)6]3) Crystal.

[0059] Following the hydrothermal reaction, the present invention preferably further includes sequentially washing and drying the hydrothermal reaction product. In the present invention, the number of water washes is preferably 2 to 5 times, more preferably 3 times. The present invention preferably washes the hydrothermal reaction product until no powder detaches.

[0060] In this invention, the drying temperature is preferably 50-70°C, more preferably 60°C; the drying time is preferably 12-24 hours, more preferably 24 hours.

[0061] In this invention, the carbon-based material precursor is preferably composed of a carbon matrix and Prussian blue crystals filling the pores of the carbon matrix and supported on the surface of the carbon matrix.

[0062] After obtaining the carbon-based material precursor, the present invention carbonizes the carbon-based material precursor to obtain the carbon-based material. In the present invention, the carbonization temperature is preferably 700–1000℃, more preferably 800–900℃; the carbonization time is preferably 6–8 h, more preferably 6–7 h. In the present invention, the heating rate to the required carbonization temperature is preferably 5–10℃ / min, more preferably 10℃ / min.

[0063] In this invention, the carbonization is preferably carried out in an oxygen-free atmosphere, and more preferably in an inert gas atmosphere. In this invention, the inert gas is preferably one of argon and nitrogen, and more preferably argon.

[0064] In this invention, during the carbonization process, the surface of the carbon material becomes rougher and the pore size becomes larger. At the same time, the Prussian blue crystals that fill the pores of the carbon matrix and are loaded on the surface of the carbon matrix are pyrolyzed and broken, forming a composite structure of nano-zero-valent iron particles and porous carbon material.

[0065] The present invention also provides the application of the carbon-based materials described in the above technical solutions or the carbon-based materials prepared by the preparation methods described in the above technical solutions in the purification of uranium-containing wastewater.

[0066] In this invention, the uranium-containing wastewater is preferably one or more of uranium mining and metallurgical wastewater, nuclear fuel wastewater, and spent fuel reprocessing wastewater, and more preferably uranium mining and metallurgical wastewater.

[0067] The present invention also provides a method for purifying uranium-containing wastewater, comprising the following steps:

[0068] The carbon-based material is mixed with uranium-containing wastewater for adsorption; the carbon-based material is the carbon-based material described in the above technical solution or the carbon-based material prepared by the preparation method described in the above technical solution.

[0069] In this invention, the solid-liquid ratio of the carbon-based material and the uranium-containing wastewater is preferably 1.2 to 1.6 g / L, more preferably 1.4 to 1.5 g / L.

[0070] In this invention, the concentration of uranium ions in the uranium-containing wastewater is preferably 5-250 mg / L, more preferably 40 mg / L; the pH value of the uranium-containing wastewater is preferably 3-7, more preferably 4.

[0071] In this invention, the adsorption temperature is preferably 20-40°C, more preferably 25°C; the adsorption time is preferably 2-6 hours, more preferably 3 hours.

[0072] In this invention, the adsorption is preferably carried out in an oxygen-free atmosphere, which is preferably the same as the aforementioned oxygen-free atmosphere. In this invention, adsorption in an oxygen-free environment can prevent the re-oxidation of already reduced tetravalent uranium to hexavalent uranium, and can also slow down the oxidation of nano-zero-valent iron.

[0073] The carbon-based material described in this invention is preferably recyclable. In this invention, the preferred method for recycling the carbon-based material is to soak the used carbon-based material in an eluent aqueous solution for desorption, followed by solid-liquid separation to obtain the recycled carbon-based material. In this invention, the eluent in the eluent aqueous solution is preferably one of sodium carbonate, sodium bicarbonate, dilute hydrochloric acid, and dilute nitric acid, more preferably sodium carbonate. In this invention, the concentration of the eluent aqueous solution is preferably 0.2–1 mol / L, more preferably 0.5 mol / L.

[0074] In this invention, the desorption temperature is preferably 25–30°C, more preferably 25°C; the desorption time is preferably 2–6 h, more preferably 3 h. The carbon-based material prepared by this invention does not require the addition of a catalyst during the desorption reaction, nor does it require the use of highly toxic cleaning agents such as chloroform or N,N-dimethylformamide (DMF) to clean and centrifuge the desorbed material again (this process causes secondary pollution). This invention uses a simple immersion method, directly placing the adsorbed material into the eluent for immersion and desorption. Uranium ions are desorbed into the eluent, and then uranium resources are recovered through the eluent aqueous solution. This method is environmentally friendly, does not cause secondary pollution, and has broad practical application prospects.

[0075] In this invention, the carbon-based material is preferably recycled 3 to 5 times, more preferably 3 times.

[0076] To further illustrate the present invention, the carbon-based materials provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0077] Example 1

[0078] Add 1.32 g potassium ferricyanide (K3[Fe(CN)6]) and 0.5 g glucose (α-D-C6H) to 60 mL of ultrapure water. 12 O6) was stirred at room temperature and 650 r / min for 5 min to obtain a mixed solution; then 1 mL of concentrated hydrochloric acid (concentration of 36% to 38%) was added, and stirring was continued for 5 min to disperse the hydrochloric acid evenly, to obtain a precursor solution with a pH value of 1;

[0079] The precursor solution and 0.5 g of carbon felt substrate (CF, size 20*50 mm, thickness 3 mm) were transferred to a 100 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene and subjected to hydrothermal reaction at 120 °C for 4 h. The hydrothermal reaction product was washed three times with ultrapure water until no powder fell off. After drying at 60 °C for 24 h, a carbon-based material precursor (PB@CF) loaded with Prussian blue crystals was obtained.

[0080] The carbon-based material precursor was heated from room temperature to 700°C at a heating rate of 10°C / min and carbonized in an Ar atmosphere at 700°C for 6 hours. After cooling to room temperature, the carbon-based material (nZVI@CF700) was obtained.

[0081] Example 2

[0082] Add 1.32 g potassium ferricyanide (K3[Fe(CN)6]) and 0.5 g glucose (α-D-C6H) to 60 mL of ultrapure water. 12 O6) was stirred at room temperature and 650 r / min for 5 min to obtain a mixture; then 1 mL of concentrated hydrochloric acid was added to make the pH of the mixture 1, and stirring was continued for 5 min to make the hydrochloric acid evenly dispersed to obtain the precursor solution;

[0083] The precursor solution and 0.5 g of carbon felt substrate (CF, size 20*50 mm, thickness 3 mm) were transferred to a 100 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene and subjected to hydrothermal reaction at 120 °C for 4 h. The hydrothermal reaction product was washed three times with ultrapure water until no powder fell off. After drying at 60 °C for 24 h, a carbon-based material precursor (PB@CF) loaded with Prussian blue crystals was obtained.

[0084] The carbon-based material precursor was heated from room temperature to 800°C at a heating rate of 10°C / min and carbonized in an Ar atmosphere at 800°C for 6 hours. After cooling to room temperature, the carbon-based material (nZVI@CF800) was obtained.

[0085] Example 3

[0086] Add 1.32 g potassium ferricyanide (K3[Fe(CN)6]) and 0.5 g glucose (α-D-C6H) to 60 mL of ultrapure water. 12 O6) was stirred at room temperature and 650 r / min for 5 min to obtain a mixture; then 1 mL of concentrated hydrochloric acid was added to make the pH of the mixture 1, and stirring was continued for 5 min to make the hydrochloric acid evenly dispersed to obtain the precursor solution;

[0087] The precursor solution and 0.5 g of carbon felt substrate (CF, size 20*50 mm, thickness 3 mm) were transferred to a 100 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene and subjected to hydrothermal reaction at 120 °C for 4 h. The hydrothermal reaction product was washed three times with ultrapure water until no powder fell off. After drying at 60 °C for 24 h, a carbon-based material precursor (PB@CF) loaded with Prussian blue crystals was obtained.

[0088] The carbon-based material precursor was heated from room temperature to 900°C at a heating rate of 10°C / min and carbonized at 900°C in an Ar atmosphere for 6 hours. After cooling to room temperature, the carbon-based material (nZVI@CF900) was obtained.

[0089] Example 4

[0090] Add 1.32 g potassium ferricyanide (K3[Fe(CN)6]) and 0.5 g glucose (α-D-C6H) to 60 mL of ultrapure water. 12 O6) was stirred at room temperature and 650 r / min for 5 min to obtain a mixture; then 1 mL of concentrated hydrochloric acid was added to make the pH of the mixture 1, and stirring was continued for 5 min to make the hydrochloric acid evenly dispersed to obtain the precursor solution;

[0091] The precursor solution and 0.5 g of carbon felt substrate (CF, size 20*50 mm, thickness 3 mm) were transferred to a 100 mL stainless steel high-pressure reactor lined with polytetrafluoroethylene and subjected to hydrothermal reaction at 120 °C for 4 h. The hydrothermal reaction product was washed three times with ultrapure water until no powder fell off. After drying at 60 °C for 24 h, a carbon-based material precursor (PB@CF) loaded with Prussian blue crystals was obtained.

[0092] The carbon-based material precursor was heated from room temperature to 1000℃ at a heating rate of 10℃ / min and carbonized at 1000℃ in an Ar atmosphere for 6 hours. After cooling to room temperature, the carbon-based material (nZVI@CF1000) was obtained.

[0093] Test Example 1

[0094] The carbon-based material precursors (PB@CF) and carbon-based materials (nZVI@CF700-1000) prepared in Examples 1-4 were characterized, XRD analyzed, and XPS analyzed. The results are shown below.

[0095] Figure 1 The images shown are SEM images of the carbon-based material precursors (PB@CF) prepared in Examples 1-4, magnified 500 times. Figure 2 The images shown are SEM images of the carbon-based material precursors (PB@CF) prepared in Examples 1-4, magnified 100,000 times. Figure 1 and Figure 2 It is known that the formation of a compact and uniformly distributed Prussian blue (PB) crystal layer on the carbon matrix surface makes the carbon matrix surface rougher.

[0096] Figure 3 The images show the XRD patterns of the carbon-based material precursors (PB@CF) prepared in Examples 1-4. Figure 3 It can be seen that there is a distinct characteristic diffraction peak at 2θ = 26.22°, corresponding to the (002) crystal plane of the carbon matrix (refer to standard card JCPDs No. 75-1621). At the same time, characteristic diffraction peaks of different heights are observed at 2θ = 17.37°, 35.16°, 39.49°, 50.67°, 53.89°, 57.17°, 66.23°, and 68.99°, corresponding to the (100), (200), (210), (220), (300), (310), (320), and (321) crystal planes of Prussian blue crystal (refer to standard card JCPDs No. 01-0239), respectively. This indicates that the carbon-based material precursor (PB@CF) has been successfully prepared.

[0097] Figure 4 The image shows the SEM spectrum of the carbon-based material (nZVI@CF700) prepared in Example 1. Figure 4 It can be seen that after carbonization at 700℃, the Prussian blue crystals in the carbon-based material precursor begin to break down, and nano-zero-valent iron particles begin to form on the surface of the carbon felt substrate.

[0098] Figure 5 The image shows the SEM spectrum of the carbon-based material (nZVI@CF800) prepared in Example 2. Figure 5It can be seen that after carbonization at 800℃, the Prussian blue crystals in the carbon-based material precursor have been broken, forming a large number of uniformly distributed spherical zero-valent iron nanoparticles with a diameter of about 200-300nm on the surface of the carbon felt substrate, which greatly increases the contact area of ​​the active sites.

[0099] Figure 6 This is a SEM image of the carbon-based material (nZVI@CF900) prepared in Example 3. Figure 6 It can be seen that after carbonization at 900℃, the Prussian blue crystals in the carbon-based material precursor are completely broken, the surface of the carbon felt substrate also begins to break, and nano-zero-valent iron particles appear inside the carbon felt substrate.

[0100] Figure 7 The image shows the SEM spectrum of the carbon-based material (nZVI@CF1000) prepared in Example 4. Figure 7 It can be seen that after carbonization at 1000℃, the surface of the carbon felt substrate in the carbon-based material precursor is damaged, and there are uniformly distributed nano-zero-valent iron particles inside the carbon felt substrate.

[0101] Figure 8 The images show the XRD patterns of the carbon-based materials and carbon felt substrates prepared in Examples 1-4. Figure 8 It can be seen that although some impurity peaks appeared in the sample, both the carbon felt substrate and nZVI@CF700~1000 had characteristic diffraction peaks centered at 2θ=26.22°, corresponding to the (002) crystal plane of the carbon felt substrate (refer to standard card JCPDs No.75-1621), indicating that the carbon felt substrate has good structural stability. At the same time, nZVI@CF700~1000 contained characteristic diffraction peaks of different heights at 2θ=44.35°, 64.53° and 81.65°, corresponding to the (110), (200) and (211) crystal planes of nZVI (refer to standard card JCPDs No.85-1410), which also shows that nZVI@CF700~1000 nanomaterials were successfully prepared by a simple two-step hydrothermal carbonization method. Furthermore, it is evident that compared to the supported nano-zero-valent iron-doped carbon-based materials prepared at carbonization temperatures of 700℃, 900℃, and 1000℃, the nZVI@CF800 material prepared at a carbonization temperature of 800℃ exhibits more pronounced characteristic diffraction peaks of nano-zero-valent iron, indicating that nZVI@CF800 has a higher nZVI content and better adsorption-reduction capabilities.

[0102] Figure 9 XPS spectra of the carbon-based materials prepared in Examples 1-4. Figure 9It can be seen that the carbon-based materials prepared in Examples 1 to 4 all have obvious absorption peaks for C, O and Fe elements. Compared with nZVI@CF700, nZVI@CF900 and nZVI@CF1000, nZVI@CF800 has a higher content of O and Fe elements.

[0103] Figure 10 This is a high-resolution XPS spectrum of Fe 2p energy from the carbon-based material (nZVI@CF800) prepared in Example 2. Figure 10 It can be seen that there are obvious absorption peaks at 707.10 eV and 718.56 eV, which belong to Fe, respectively. 0 2p 3 / 2 peak and 2p 1 / 2 peak.

[0104] Test Example 2

[0105] The adsorption properties of the carbon-based materials prepared in Examples 1-4 were tested using the following methods:

[0106] Weigh 70 mg of carbon material (specifically, a carbon felt substrate with a thickness of 3 mm and a size of 5*20 mm) and the carbon-based material prepared in Examples 1-4 (nZVI@CF700-1000, specifically, a carbon felt substrate with a thickness of 3 mm and a size of 5*20 mm), and add them to a beaker containing 50 mL of a uranium ion-containing aqueous solution with a concentration of 10 mg / L and a pH of 4. Adsorption is carried out for 3 hours under an argon atmosphere and a constant temperature of 25°C in a water bath. During the reaction, the adsorption is performed at regular intervals (e.g.,...). Figure 11 (As shown) The supernatant was taken, and the concentration of uranyl ions before and after adsorption was determined by azoarsin III spectrophotometry. The test results are shown below.

[0107] Figure 11 Schematic diagrams showing the adsorption of uranium-containing ion aqueous solutions by carbon materials and the carbon-based materials prepared in Examples 1-4. Figure 11 It is known that under the same conditions, the carbon felt substrate has almost no adsorption effect; while the carbon-based material prepared by the present invention has a very good adsorption effect. It is further shown that the carbon-based materials prepared by the present invention can adsorb more than 90% of uranyl ions within 120 min. Among them, nZVI@CF800 has the best adsorption effect. This may be attributed to the fact that compared with other adsorbent materials, nZVI@CF800 has the highest nZVI content, the most nZVI reactive sites, and a faster removal rate.

[0108] Figure 12 The images show the XPS full spectrum of the carbon-based material prepared in Example 2 before and after adsorption of uranium ions. Figure 12 It can be seen that in the XPS full spectrum after adsorption, obvious U4f was found at 382.35 eV and 391.00 eV. 7 / 2 and U4f5 / 2 The bond energy peaks indicate that uranyl ions were successfully loaded onto nZVI@CF800.

[0109] Figure 13 This is a high-resolution U4f spectrum of the carbon-based material prepared in Example 2 before and after adsorption of uranium ions. Figure 13 It can be seen that U(VI) has 4f 7 / 2 and 4f 5 / 2 The peaks are located at 382.57 eV and 393.40 eV, while the corresponding U(IV) peaks appear at 381.75 eV and 392.48 eV. Furthermore, based on peak area fitting, we calculated the ratio of U(VI) peak intensity to U(IV) peak intensity to be 43.2:56.8, thus confirming the reduction of U(VI).

[0110] Figure 14 The images show the XRD patterns of the carbon-based material prepared in Example 2 before and after adsorption of uranium ions. Figure 14 It can be seen that the characteristic peak (002) of the carbon felt substrate still exists in nZVI@CF800-U at 26.01°, indicating that the adsorbent material and UO2 are in good condition. 2+ The carbon felt substrate remained relatively stable during the process. The characteristic peak at 14.16° after adsorption corresponds to the (020) crystal plane of FeOOH (refer to standard card JCPDs No. 70-0714), and the characteristic peak at 35.68° corresponds to the (119) crystal plane of Fe2O3 (refer to standard card JCPDs No. 25-1402). This indicates that Fe... 0 Adsorption and reduction of UO2 2+ It is oxidized to FeOOH and Fe2O3. Meanwhile, the peaks at 12.03° and 28.28° correspond to the (002) crystal plane of UO3·2H2O (refer to standard card JCPDs No. 18-1436) and the (111) crystal plane of UO2 (refer to standard card JCPDs No. 41-1422), respectively. This may be due to the synergistic complexation of UO2 by the FeOOH hydroxyl groups. 2+ Hydrolysis precipitation and Fe 0 UO2 2+ This is due to the reduction effect, indicating that nZVI@CF800 successfully reduced UO2. 2+ Adsorption and reduction were carried out.

[0111] Test Example 3

[0112] 70 mg of the carbon-based material (nZVI@CF800, specifically 3 mm thick and 5*20 mm in size) prepared in Example 2 was weighed and added to a beaker containing 50 mL of uranium ion-containing aqueous solution with different pH values ​​(pH values ​​of 2-7) at a concentration of 10 mg / L. Adsorption was carried out for 5 h under an argon atmosphere and a constant temperature of 25°C in a water bath. The supernatant was collected every 30 min during the reaction, and the concentration of uranium ions before and after adsorption was determined using the azoarsin III spectrophotometric method. The test results are shown below.

[0113] Figure 15 Adsorption effects of the carbon-based materials prepared in Example 2 on uranium ions under different pH conditions are shown in the graphs. Figure 15 It is known that uranyl precipitates spontaneously in an alkaline environment, therefore... Figure 15 As can be seen, the nZVI@CF800 adsorbent material can effectively adsorb and reduce uranyl to purify pollutants in water under both acidic and neutral environments, demonstrating good stability.

[0114] Test Example 4

[0115] Weigh 70 mg of the carbon-based material (nZVI@CF800, specifically 3 mm thick and 5*20 mm in size) prepared in Example 2 and add it to a beaker containing 50 mL of a 10 mg / L aqueous solution of uranium ions. Adsorption is carried out for 1.5 h under an argon atmosphere and at different water bath temperatures. The reaction proceeds at certain time intervals (e.g., ...). Figure 16 (As shown) The supernatant was separated, and the concentration of uranium ions before and after adsorption was determined by azoarsin III spectrophotometry. The test results are shown below.

[0116] Figure 16 The graph shows the adsorption effect of the carbon-based material prepared in Example 2 on uranium ions at different adsorption temperatures. Figure 16 It can be seen that the nZVI@CF800 adsorbent material has a wide range of environmental temperature adaptability and can remove most of the uranyl ions in a very short time under different temperature conditions.

[0117] Test Example 5

[0118] Weigh 70 mg of the carbon-based material (nZVI@CF800, specifically 3 mm thick and 5*20 mm in size) prepared in Example 2, and add it to a beaker containing aqueous solutions of uranium ions of different concentrations. Adsorption is carried out for 2 hours under an argon atmosphere and a water bath at a constant temperature of 25°C. The reaction proceeds at certain time intervals (e.g., ...). Figure 17 (As shown) The supernatant was taken, and the concentration of uranium ions before and after adsorption was determined by azoarsin III spectrophotometry. The test results are shown below.

[0119] Figure 17This image shows the adsorption effect of the carbon-based material prepared in Example 2 on uranium ions of different concentrations. Figure 17 It can be seen that the nZVI@CF800 adsorbent material also has an excellent removal effect on high concentrations of uranyl ion solutions.

[0120] Test Example 6

[0121] The selectivity of the carbon-based material (nZVI@CF800) described in Example 2 for uranyl ions was tested using the following method:

[0122] 70 mg of the carbon-based material nZVI@CF800 prepared in Example 2 (specifically, 3 mm thick and 5*20 mm in size) was weighed and added to a beaker containing 50 mL of 40 mg / L uranium ion-containing aqueous solution and 0.001 mol / L aqueous solutions of different anions and cations. Adsorption was carried out under an argon atmosphere and a constant temperature of 25 °C in a water bath. After 3 h of adsorption, the supernatant was collected, and the concentration of uranium ions before and after adsorption was determined by azoarsin III spectrophotometry. The test results are shown below.

[0123] Figure 18 This image shows the adsorption effect of the carbon-based material described in Example 2 on uranium ions under different cation conditions. Figure 18 It can be seen that, compared with the control group containing only 40 mg / L uranyl ions, all cations significantly improved the removal of UO2 by nZVI@CF800. 2+ The impacts are all relatively small, UO2 2+ The removal rate can reach over 90%.

[0124] Figure 19 This image shows the adsorption effect of the carbon-based material described in Example 2 on uranium ions under different anion conditions. Figure 19 It can be seen that, in addition to CO3, other anions include... 2- nZVI@CF800 for UO2 2+ The removal rate can still reach over 90%. This is mainly due to UO2. 2+ Can react with CO3 2- The combination forms a uranyl carbonate complex with a significant stability coefficient, hindering the adsorption material from reacting with UO2. 2+ The reaction, therefore CO3 2- It exhibits a certain inhibitory effect. From the above analysis, it is clear that nZVI@CF800 has an inhibitory effect on UO2. 2+ It has excellent selectivity and great potential for practical application.

[0125] Test Example 7

[0126] The carbon-based material (nZVI@CF800) prepared in Example 2 was tested for its ability to extract uranium from seawater. The test method was as follows:

[0127] Weigh 70 mg of the carbon-based material nZVI@CF800 prepared in Example 2 (specifically, 3 mm thick and 5*20 mm in size) and add it to a beaker containing 50 mL of simulated seawater containing 5 mg / L uranium ions. Adsorption is carried out for 3 hours under an argon atmosphere and a water bath at a constant temperature of 25°C. The reaction is performed at certain time intervals (e.g., ...). Figure 20 (As shown) The supernatant was taken, and the concentration of uranyl ions before and after adsorption was determined by azoarsin III spectrophotometry. The test results are shown below.

[0128] Figure 20 This is a graph showing the test results of the uranium extraction capability of the carbon-based material prepared in Example 2 from seawater. Figure 20 It can be seen that after nZVI@CF800 adsorbs in 50 mL of simulated seawater with a uranyl ion concentration of 5 mg / L for 180 min, UO2 2+ The removal rate reached 94.25%, and the uranium adsorption capacity reached 62.66 mg / g, proving that nZVI@CF800 still effectively removes UO2 in simulated seawater. 2+ It exhibits excellent adsorption properties. Therefore, nZVI@CF800 has promising application prospects in the field of uranium extraction from seawater.

[0129] Test Example 8

[0130] The cycling performance of the carbon-based material (nZVI@CF800) prepared in Example 2 was tested using the following method:

[0131] 70 mg of the carbon-based material nZVI@CF800 prepared in Example 2 (specifically, 3 mm thick and 5*20 mm in size) was weighed and added to a beaker containing 50 mL of 40 mg / L uranium ion-containing aqueous solution. Adsorption was performed under an argon atmosphere and a water bath at a constant temperature of 25°C for 3 hours. After adsorption, nZVI@CF800 was removed and placed in a beaker containing 50 mL of 0.5 mol / L sodium carbonate eluent for immersion and desorption at room temperature for 3 hours. After desorption, it was removed and directly placed into a beaker containing 50 mL of 40 mg / L uranium ion-containing aqueous solution for adsorption under the same conditions for 3 hours. Cyclic performance testing was then performed. The above process was carried out at certain time intervals (e.g., ...). Figure 21 (As shown) The supernatant was taken and the concentration of uranyl ions was determined by azoarsin III spectrophotometry. The test results are shown below.

[0132] Figure 21 This image shows the adsorption effect of the carbon-based material prepared in Example 2 on uranium ions after three cycles of testing. Figure 21 It can be seen that after three cycles of testing, the UO2 of nZVI@CF800... 2+The removal rate is still better than 80%, and compared with other powdered adsorbents, nZVI@CF800 is easier to operate and more conducive to the recovery of uranium resources.

[0133] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A carbon-based material for purifying uranium-containing wastewater, characterized in that, The material comprises a carbon matrix and nano-zero-valent iron particles filling the pores of the carbon matrix and supported on the surface of the carbon matrix; the mass content of the nano-zero-valent iron particles in the carbon-based material is 4-6%. The method for preparing the carbon-based material includes the following steps: Potassium ferricyanide, glucose, pH adjuster and water are mixed to obtain the precursor solution; The precursor liquid and carbon material are mixed and subjected to a hydrothermal reaction to obtain a carbon-based material precursor. The carbon-based material precursor is carbonized to obtain the carbon-based material. The carbon material is composed of carbon fibers; the mass ratio of the carbon material, potassium ferricyanide and glucose is 1:2 to 3:

1.

2. The carbon-based material for purifying uranium-containing wastewater according to claim 1, characterized in that, The particle size of the nano-zero valent iron particles is 200~300nm.

3. The method for preparing the carbon-based material for purifying uranium-containing wastewater as described in claim 1 or 2, characterized in that, Includes the following steps: Potassium ferricyanide, glucose, pH adjuster and water are mixed to obtain the precursor solution; The precursor liquid and carbon material are mixed and subjected to a hydrothermal reaction to obtain a carbon-based material precursor. The carbon-based material precursor is carbonized to obtain the carbon-based material. The carbon material is composed of carbon fibers; the mass ratio of the carbon material, potassium ferricyanide and glucose is 1:2 to 3:

1.

4. The preparation method according to claim 3, characterized in that, The hydrothermal reaction is carried out at a temperature of 110~130℃ for 4~6 hours.

5. The preparation method according to claim 3, characterized in that, The carbonization temperature is 700~1000℃, and the time is 6~8h.

6. The application of a carbon-based material for purifying uranium-containing wastewater according to claim 1 or 2, or a carbon-based material prepared by the preparation method according to any one of claims 3 to 5, in purifying uranium-containing wastewater.

7. A method for purifying uranium-containing wastewater, characterized in that, Includes the following steps: The carbon-based material is mixed with uranium-containing wastewater for adsorption; the carbon-based material is the carbon-based material for purifying uranium-containing wastewater as described in claim 1 or 2, or the carbon-based material prepared by the preparation method described in any one of claims 3 to 5.

8. The method for purifying uranium-containing wastewater according to claim 7, characterized in that, The solid-liquid ratio of the carbon-based material and the uranium-containing wastewater is 1.2~1.6 g / L.

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