A method for preparing a solid catalytic material with a surface rich in hydrogen-bonding microenvironments and its use in the separation of uranium

Abstract

The application relates to the technical field of chemical materials, and particularly discloses a preparation method of solid catalytic material with a surface rich in hydrogen bond microenvironment and application of the solid catalytic material in uranium separation, and the preparation method comprises the following steps: after washing and drying a metal material, the metal material is placed in a plasma reactor, then gas is introduced, plasma treatment is carried out, vacuum annealing is carried out after the treatment is completed, and the solid catalytic material is obtained. The application introduces a hydrogen bond special microenvironment on the surface of the metal material, has good photocatalytic uranium separation performance, realizes uranium separation in radioactive wastewater, and solves the problem that powder state photocatalytic materials are not applicable in actual popularization and application.

Description

Technical Field

[0001] This invention belongs to the field of materials chemistry, and particularly relates to a method for preparing a solid catalytic material with a surface rich in hydrogen bond microenvironment and its application in uranium separation. Background Technology

[0002] The mining and smelting processes of uranium generate large quantities of waste rock, tailings (slag), and wastewater containing long-lived natural radioactive nuclides such as uranium and radium, causing radioactive pollution of soil and groundwater. Uranium, radium, and other radioactive nuclides possess both chemical toxicity and radioactive hazards, posing a potential health risk to the public upon release into the environment. Therefore, timely and scientific remediation of contaminated uranium mine sites is necessary. my country's uranium mines are complex in type, employ diverse mining methods, and face significant environmental problems. Long-term leaching and infiltration at hard-rock uranium mine shaft industrial sites, hydrometallurgical plants, and tailings (slag) ponds can all lead to radioactive pollution of soil and seepage water.

[0003] As the largest single nuclear facility, uranium tailings storage sites have always been a focus of attention for the ecological and environmental protection departments. The pollution characteristics of uranium-contaminated sites in my country exhibit several key features: (1) large contaminated areas with a clear vertical distribution of pollution; (2) contaminated sites typically contain multiple media and environmental factors, leading to complex causes of site contamination; and (3) uranium contamination at these sites is accompanied by heavy metal toxicity and radioactive risks, posing a greater threat than general heavy metal contamination. In summary, developing a low-cost, highly adaptable "multi-field coupling" remediation technology for typical uranium-contaminated sites is one of the urgent technical challenges that my country's nuclear industry needs to address.

[0004] Existing technologies utilize photocatalytic materials to treat uranium-containing wastewater, enabling the separation of uranium from the water and reducing radionuclide contamination. However, most photocatalytic materials are currently in powder form, making them unsuitable for practical application.

[0005] In summary, this paper provides a method for preparing a solid catalytic material with a surface rich in hydrogen bond microenvironment and its application in uranium separation, while solving the problem that powdered photocatalytic materials are not suitable for practical applications. Summary of the Invention

[0006] In view of the shortcomings and deficiencies of the prior art, the present invention provides a method for preparing a solid catalytic material with a surface rich in hydrogen bond microenvironment and its application in uranium separation. By introducing a special hydrogen bond microenvironment on the surface of the metal catalytic material, it has excellent photocatalytic uranium separation performance, and can convert soluble U(VI) into slightly soluble or sparingly soluble uranium oxides. This not only achieves uranium separation from wastewater, but also solves the problem that powdered photocatalytic materials are not suitable for practical application.

[0007] The technical solution of the present invention is as follows:

[0008] A method for preparing a solid catalytic material rich in surface hydrogen bond microenvironment includes the following steps:

[0009] After cleaning and drying the metal material, it is placed in a plasma reactor, then gas is introduced, high-frequency glow discharge is initiated, and plasma treatment is performed. After the treatment is completed, vacuum annealing is performed to obtain the solid catalytic material.

[0010] The plasma treatment process conditions include: plasma injection voltage 2.5–100 keV, and plasma injection dose 10. 12 ~10 20 ions. Preferably, the plasma injection voltage is 7.5–50 keV and the plasma injection dose is 10 12 ~10 17 More preferably, the plasma injection voltage is 10 keV and the plasma injection dose is 10 ions. 16 ions.

[0011] Preferably, the metal material is a porous material, a thin film material, a sheet material, a plate material, or a block material with a metal coating on its surface. More preferably, the metal material is a porous material with a pore size of 1-500 μm, and even more preferably, the pore size is 150-250 μm.

[0012] Preferably, the metal is one of iron, cobalt, nickel, copper, and their alloys. More preferably, the metal is nickel.

[0013] More preferably, the metal is nickel mesh or nickel foam with a pore size of 200 μm.

[0014] Preferably, the gas includes one or both of hydrogen and oxygen, and hydrogen plasma or oxygen plasma is generated accordingly during plasma treatment. The flow rate of the gas is 10–50 sccm.

[0015] More preferably, the gas comprises hydrogen and oxygen, and the flow rates of both hydrogen and oxygen are 20 to 40 sccm.

[0016] Preferably, the plasma is a glow discharge plasma. High-frequency glow discharge reaction is used to activate O and H into active particles (such as charged ions or free radicals). These active particles diffuse onto the surface of the metal mesh / foam and react with it, ultimately forming MOH groups on the surface of the metal oxide.

[0017] Preferably, the conditions for vacuum annealing include: vacuum degree 0~5×10 -5 Pa, annealing temperature 50–300℃, annealing time 1–6 h. More preferably, vacuum degree 0.5 × 10⁻⁶. -5 ~5×10-5 Pa, annealing temperature 50–150℃, annealing time 2–4 h. More preferably, vacuum degree 1×10⁻⁶. -5 Pa, annealing temperature is 100℃, annealing time is 3h.

[0018] Preferably, the metal material is cleaned using one or both of acetone and ethanol.

[0019] The present invention also provides an application of the solid catalytic material prepared by the above method in uranium separation.

[0020] As a preferred embodiment, the application method includes: placing a solid catalytic material in uranium-containing wastewater and carrying out a photocatalytic reaction under light irradiation, thereby separating uranium from the wastewater.

[0021] Preferably, the illumination can be natural light or electric light source (such as a 300W xenon lamp).

[0022] The amount of solid catalyst material can be selected arbitrarily according to actual needs.

[0023] The beneficial effects of this invention are as follows:

[0024] 1. The present invention provides a simple method for preparing solid catalytic materials by constructing a unique hydrogen-bonded microenvironment on the surface through plasma injection. This enhances the electron capture of the catalytic material, stabilizes low-energy electrons, increases electron lifetime, and promotes surface free radical reactions under electron-rich conditions. The unique hydrogen-bonded microenvironment on the catalytic material surface also facilitates the co-adsorption of nitrogen / oxygen, uranyl, and water vapor, forming symmetry-breaking centers. The captured low-energy electrons at these symmetry-breaking centers with significant charge density gradients generate various adsorption intermediates, which helps in the precise control of uranium-containing products.

[0025] 2. The solid catalytic material of this invention exhibits a wide range of light absorption characteristics in the ultraviolet to visible light band, enabling maximum utilization of the solar spectrum. It has excellent photocatalytic separation performance of uranium, and can convert soluble U(VI) into slightly soluble or sparingly soluble uranium oxides. Moreover, it can achieve good photocatalytic effects without sacrificial agents. It can form a piezoelectric field under mechanical force, providing driving force for photoinduced charges, enhancing separation and inhibiting recombination. Attached Figure Description

[0026] Figure 1 A schematic diagram simulating the plasma injection range under different injection voltages;

[0027] Figure 2 The change in water contact angle of metallic materials before and after plasma injection;

[0028] Figure 3 The X-ray diffraction pattern of the solid catalytic material prepared in this invention is shown below.

[0029] Figure 4 The Fourier transform infrared spectrum of the solid catalytic material prepared in this invention is shown below.

[0030] Figure 5 The X-ray photoelectron spectrum of O in the solid catalytic material prepared in this invention is shown below.

[0031] Figure 6 The image shows the X-ray photoelectron spectrum of Ni in the solid catalytic material prepared in this invention.

[0032] Figure 7 The results of the photocatalytic separation of uranium using the solid catalytic material prepared in this invention in simulated wastewater and real uranium mine wastewater are shown.

[0033] Figure 8 The results of multiple cycle experiments were conducted on the solid catalytic material prepared in this invention in uranium-containing wastewater.

[0034] Figure 9 The effect of plasma injection dosage on the removal rate of uranium from uranium-containing wastewater;

[0035] Figure 10 The effect of annealing temperature on the removal rate of uranium from uranium-containing wastewater;

[0036] Figure 11 The effect of different metal materials on the removal rate of uranium in uranium-containing wastewater. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Unless otherwise specified, all reagents involved in the embodiments of this invention are commercially available products and can be purchased through commercial channels.

[0039] Example 1

[0040] This embodiment provides a method for preparing a solid catalytic material rich in surface hydrogen bond microenvironment, including the following steps:

[0041] (1) Cut the nickel mesh (purity 99.9%, thickness 0.1 mm, aperture 200 μm) to a size of 10 cm × 10 cm, clean it with acetone and ethanol by ultrasonic cleaning, and then blow it dry with nitrogen.

[0042] (2) Place the nickel mesh obtained in step (1) in the plasma reactor and fix it on the stage of the plasma reaction chamber. Then, introduce gas (hydrogen and oxygen, both at a flow rate of 30 sccm), start high-frequency glow discharge, adjust the voltage to 10 keV, and perform plasma treatment. The plasma (hydrogen plasma and oxygen plasma) injection dose is 10. 16 In the plasma reactor, a counter records the plasma injection dose. When the counter reaches the dose, the plasma treatment is completed. Using a high-frequency glow discharge reaction, O and H are activated into active particles (such as charged ions or free radicals). The active particles diffuse to the surface of the metal mesh / foam and react with the metal mesh / foam, eventually forming MOH groups on the surface of the metal oxide.

[0043] (3) The nickel mesh processed in step (2) is placed in a tube furnace for vacuum annealing to obtain the solid catalyst material. The annealing conditions are: vacuum degree 1×10 -5 Pa, annealing temperature 100℃, time 3h.

[0044] Example 2

[0045] The difference between this embodiment and Embodiment 1 is that the introduced gas is hydrogen, and the hydrogen plasma injection voltage is 2.5 keV.

[0046] Example 3

[0047] The difference between this embodiment and Embodiment 1 is that the introduced gas is hydrogen, and the hydrogen plasma injection voltage is 5 keV.

[0048] Example 4

[0049] The difference between this embodiment and Embodiment 1 is that the introduced gas is hydrogen, and the hydrogen plasma injection voltage is 7.5 keV.

[0050] Example 5

[0051] The difference between this embodiment and Embodiment 1 is that the introduced gas is hydrogen, and the hydrogen plasma injection voltage is 10 keV.

[0052] Example 6

[0053] The difference between this embodiment and Embodiment 1 is that the introduced gas is hydrogen, and the hydrogen plasma injection voltage is 30 keV.

[0054] Example 7

[0055] The difference between this embodiment and Embodiment 1 is that the introduced gas is hydrogen, and the hydrogen plasma injection voltage is 50 keV.

[0056] Example 8

[0057] The difference between this embodiment and Embodiment 1 is that the introduced gas is oxygen, and the oxygen plasma injection voltage is 50 keV.

[0058] Example 9

[0059] The difference between this embodiment and Embodiment 1 is that the gas introduced is oxygen.

[0060] Example 10

[0061] The difference between this embodiment and Embodiment 1 is that the plasma injection dose is 10. 12 ions.

[0062] Example 11

[0063] The difference between this embodiment and Embodiment 1 is that the plasma injection dose is 10. 13 ions.

[0064] Example 12

[0065] The difference between this embodiment and Embodiment 1 is that the plasma injection dose is 10. 14 ions.

[0066] Example 13

[0067] The difference between this embodiment and Embodiment 1 is that the plasma injection dose is 10. 15 ions.

[0068] Example 14

[0069] The difference between this embodiment and Embodiment 1 is that the plasma injection dose is 10. 17 ions.

[0070] Example 15

[0071] The difference between this embodiment and Embodiment 1 is that the annealing temperature is 50°C.

[0072] Example 16

[0073] The difference between this embodiment and Embodiment 1 is that the annealing temperature is 150°C.

[0074] Example 17

[0075] The difference between this embodiment and Embodiment 1 is that the annealing temperature is 200°C.

[0076] Example 18

[0077] The difference between this embodiment and Embodiment 1 is that the annealing temperature is 250°C.

[0078] Example 19

[0079] The difference between this embodiment and Embodiment 1 is that the annealing temperature is 300°C.

[0080] Example 20

[0081] The difference between this embodiment and Embodiment 1 is that the metal mesh material is Fe.

[0082] Example 21

[0083] The difference between this embodiment and Embodiment 1 is that the metal mesh material is Co.

[0084] Example 22

[0085] The difference between this embodiment and Embodiment 1 is that the metal mesh material is Cu.

[0086] I. Characterization of the effect of plasma treatment on the preparation of solid catalytic materials according to the present invention

[0087] 1. Simulation of plasma injection range under different injection voltages

[0088] Simulation Examples 2-8 show the injection range of hydrogen plasma (H) or oxygen plasma (O) in nickel materials under different injection voltages. The results are shown in [Figure 1]. Figure 1 . Figure 1 The coordinate system formed by the distance in the X-axis direction and the distance in the Y-axis direction is shown. The straight line represents the case where the oxygen plasma (O) injection voltage is 50 keV, and the rest represent the case where the hydrogen plasma (H) is injected. The penetration depth and distribution characteristics of the plasma under different conditions can be clearly observed through the coordinate distribution. As the hydrogen plasma (H) injection voltage increases, the penetration depth increases. The penetration depth of this invention is more suitable at an injection voltage of 10 keV.

[0089] 2. Changes in water contact angle of nickel material before and after plasma injection

[0090] The changes in the water contact angle of the nickel material in Example 1 before and after plasma injection are shown in the figure. Figure 2 It can be seen that after plasma injection, the formation of a special hydrogen-bonded microenvironment on the surface of the nickel material makes the surface more hydrophilic, which is beneficial for the subsequent separation of uranium from uranium-containing wastewater.

[0091] 3. X-ray diffraction results of solid catalytic materials

[0092] X-ray diffraction was performed on the solid catalysts prepared in Example 1 (simultaneous injection of hydrogen plasma and oxygen plasma) and Example 9 (injection of oxygen plasma only). The results are shown in the figure. Figure 3The results showed that the solid catalytic material still mainly maintained the crystal structure of elemental nickel, indicating that the plasma injection process did not significantly affect the main structure of the nickel material.

[0093] 4. Fourier transform infrared spectra of solid catalytic materials

[0094] The solid catalytic materials prepared in Example 1 (simultaneous injection of hydrogen plasma and oxygen plasma) and Example 9 (injection of oxygen plasma only) were tested using Fourier transform infrared spectroscopy. The results are shown in [Figure number missing]. Figure 4 The results showed that unique hydrogen bond signals appeared in the nickel material after O and H implantation, which further confirmed the formation of hydrogen bond microenvironment on the material surface.

[0095] 5. X-ray photoelectron spectroscopy of solid catalytic materials

[0096] Figure 5 and Figure 6 X-ray photoelectron spectroscopy (XPS) data of solid catalytic materials prepared from nickel material in Example 1 after implantation with hydrogen plasma and oxygen plasma (O, H) are presented respectively. Analysis results show that, with the progress of plasma implantation, substances similar to NiO and NiOOH appear in the nickel material, which helps to understand the chemical changes of the material during plasma treatment.

[0097] II. Application of the solid catalytic material of this invention in uranium separation

[0098] The solid catalytic material (20mm×20mm in size) prepared in this invention is placed in uranium-containing wastewater and subjected to photocatalytic reaction under a 300W xenon lamp to separate uranium from the wastewater.

[0099] 1. Experimental results of photocatalytic separation of uranium from simulated wastewater and real uranium mine wastewater using solid catalyst materials

[0100] Figure 7 The experimental results of photocatalytic uranium fixation using the solid catalyst material prepared in Example 1 in simulated wastewater and real uranium mining wastewater are presented. The horizontal axis represents the reaction time, and the vertical axis represents the ratio of the remaining soluble uranium concentration in the wastewater to the initial soluble uranium concentration in the wastewater at different reaction times (C). T / C0). Experimental results show that as the reaction time increases, C T The gradually decreasing CO / C ratio indicates that the concentration of soluble uranium in the uranium mine wastewater gradually decreases and tends to stabilize from 120 min onwards. This shows that the solid catalyst has a good treatment effect on uranium-containing wastewater and can significantly reduce the concentration of uranium in the wastewater.

[0101] 2. Results of multiple-cycle experiments with solid catalyst materials in uranium-containing wastewater

[0102] The solid catalyst material prepared in Example 1 was subjected to multiple cycles of testing in uranium-containing wastewater. The results are shown in the figure. Figure 8 The horizontal axis represents the number of cycles, and the vertical axis represents the uranium removal rate (%) in the uranium-containing wastewater in each experiment. The experimental results show that the material maintains a high removal rate even after multiple cycles, demonstrating good recycling capacity and stability.

[0103] 3. Effect of plasma injection dosage on uranium removal rate in uranium-containing wastewater

[0104] Solid catalytic materials prepared using different plasma injection doses in Examples 1, 10-14 were used to treat uranium-containing wastewater. The results are shown in the table below. Figure 9 The horizontal axis represents the plasma injection dose, and the vertical axis represents the uranium removal rate (%) in the uranium-containing wastewater after 120 min of treatment. Experimental results show that the uranium removal rate gradually increases with increasing plasma injection dose, reaching a maximum when the plasma injection dose reaches 10... 16 The ions tend to stabilize, resulting in a higher uranium removal rate.

[0105] 4. Effect of annealing temperature on uranium removal rate from uranium-containing wastewater

[0106] The solid catalytic materials prepared at different annealing temperatures in Examples 1, 15-19 were used to treat uranium-containing wastewater. The results are shown in the figure. Figure 10 The horizontal axis represents the annealing temperature, and the vertical axis represents the uranium removal rate (%) in uranium-containing wastewater after a treatment time of 120 min. Experimental results show that a higher uranium removal rate is obtained when the annealing temperature is 300℃.

[0107] 5. The effect of different metal materials on the removal rate of uranium in uranium-containing wastewater

[0108] Solid catalytic materials of different metals were used to treat uranium-containing wastewater in Examples 1, 20-22. The results are shown in the table below. Figure 11 The horizontal axis represents different metal materials (Fe, Co, Ni, Cu), and the vertical axis represents the uranium removal rate (%) in uranium-containing wastewater after a treatment time of 120 min. Experimental results show that the uranium removal rate of solid catalysts of different metal materials can all reach over 59.2%, with the nickel-based solid catalyst showing the highest uranium removal rate at 73.97%.

[0109] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a solid catalytic material with a surface hydrogen-bonded microenvironment for photocatalytic separation of uranium, characterized in that: Includes the following steps: After cleaning and drying the metal material, it is placed in a plasma reactor, and then gas is introduced for plasma treatment. After the treatment is completed, vacuum annealing is performed to obtain the solid catalyst material. The plasma treatment process conditions include: plasma injection voltage 7.5–50 keV, and plasma injection dose 10. 12 ~10 17 ions; The metallic material is a metal mesh; The metal is one of iron, cobalt, nickel, copper and their alloys; The gas includes one or both of hydrogen and oxygen.

2. The preparation method according to claim 1, characterized in that: The plasma is a glow discharge plasma.

3. The preparation method according to claim 1, characterized in that: The conditions for vacuum annealing include: a vacuum degree of 0.5 × 10⁻⁶. -5 ~5×10 -5 Pa, annealing temperature is 50~300℃, annealing time is 1~6h.

4. The application of a solid catalyst material prepared by the method according to any one of claims 1-3 in the separation of uranium.

5. The application according to claim 4, characterized in that: By placing solid catalytic material in uranium-containing wastewater and carrying out a photocatalytic reaction under light irradiation, uranium in the wastewater can be separated.

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