Preparation method of calcium-based porous material for adsorbing gaseous RuO4
By preparing calcium-based porous materials, the problems of irreversible adsorption and small capacity of gaseous RuO4 in existing technologies have been solved, achieving efficient RuO4 purification and meeting the needs of nuclear industry applications.
Patent Information
- Application Number
- CN202511321904.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-16
- Publication Date
- 2025-11-28
AI Technical Summary
Existing adsorbent materials adsorb gaseous RuO4 irreversibly and have a small capacity, making them unable to effectively fix the gas. This leads to blockage of ventilation system ducts and radioactive leakage, affecting the normal operation of nuclear fuel cycle facilities.
A calcium-based porous material is prepared by mixing a carrier, a pore-forming agent, and an additive to form a slurry, extruding it, calcining it at high temperature, and impregnating it with a calcium-containing solution to load calcium ions onto the porous material, thereby forming a calcium-based porous material for adsorbing gaseous RuO4.
It achieves irreversible adsorption of gaseous RuO4 with a purification efficiency of 92.5-99%, meeting the needs of nuclear industry applications and avoiding pipeline blockage and radioactive leakage.
Smart Images
Figure CN121016674A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of radioactive waste treatment and environmental protection technology, and in particular to a method for preparing a calcium-based porous material that adsorbs gaseous RuO4. Background Technology
[0002] Spent fuel reprocessing produces various volatile and semi-volatile radionuclides. Among them, ruthenium is an important volatile radioactive effluent, including... 103 Ru and 106 Ru. Metallic Ru or low-valence Ru in spent fuel is easily oxidized to ruthenium tetroxide (RuO4) when it encounters strong oxidants. This compound has a melting point of 25.4°C and a boiling point of 40°C. Therefore, under high-temperature conditions, RuO4 is often released in gaseous form. The released RuO4 undergoes self-reduction as the temperature decreases in the ventilation duct, generating black RuO2 particles that adhere to the inner wall of the stainless steel pipe, forming a local radiation source. At the same time, it can easily cause duct blockage and affect the normal operation of the ventilation system.
[0003] gaseous radioactivity 103 Ru and 106 The radioactivity of Ru reached as high as 6.62 × 10⁻⁶. 9 Bq / Nm 3 and 9.96×10 9 Bq / Nm 3 Calculations indicate that this emission level far exceeds the currently revised "Normalized Emission Limits for Nuclear Fuel Cycle Facilities" (GB13695). Therefore, it is necessary to effectively capture radioactive gaseous RuO4 at higher temperatures, before it undergoes a self-reduction reaction. Existing reports indicate that the Pacific Northwest National Laboratory in the United States has developed two adsorbent materials: silica gel spheres and steel wool. However, the adsorption of RuO4 by silica gel spheres is reversible, making effective fixation of RuO4 impossible. Steel wool is low-cost and has good industrial prospects, but due to its lack of a porous structure and small specific surface area, its adsorption capacity for RuO4 is relatively small. Summary of the Invention
[0004] This invention discloses a method for preparing calcium-based porous materials that adsorb gaseous RuO4, which solves the technical problems in the prior art.
[0005] This invention provides a method for preparing a calcium-based porous material for adsorbing gaseous RuO4, comprising: stirring a carrier and a pore-forming agent to form a mixed powder; adding water and an additive to the mixed powder and kneading and aging it for 20-24 hours to form a slurry; extruding the slurry into a slurry to obtain a porous material; drying the formed porous material at 80-120°C for 5-12 hours; calcining it at 400-1200°C for 3-8 hours; and immersing the calcined porous material in a calcium-containing solution to load calcium ions onto the porous material, thereby obtaining a calcium-based porous material for adsorbing gaseous RuO4.
[0006] In one possible implementation, the mass ratio of the carrier to the pore-forming agent is (5~10):1; and / or, the mass ratio of the carrier to water is (7.14~10):1; and / or, the mass ratio of the carrier to the additive is (8.3~25):1.
[0007] In one possible implementation, the carrier is cordierite powder; the pore-forming agent is any one of polystyrene microspheres, starch, and fly ash; and the additive is a mixed solution of ethanol and glycerol.
[0008] In one possible implementation, the extrusion pressure of the extruder is 20-50 MPa.
[0009] In one possible implementation, the calcination process is as follows: in a muffle furnace, the temperature is increased to 400°C~500°C at a heating rate of 5°C / min, calcined for 30 minutes, then increased to 800°C at a heating rate of 5°C / min, calcined for 30 minutes, and then increased to 1200°C at a heating rate of 5°C / min, calcined for 2 hours.
[0010] In one possible implementation, the calcined porous material is immersed in a calcium-containing solution at a temperature of 40°C to 80°C for 4 to 8 hours. After immersion, the porous material is removed and dried at 100 to 120°C for 22 to 26 hours.
[0011] In one possible implementation, the calcium-containing solution is at least one of calcium chloride, calcium sulfate, and calcium hypochlorite.
[0012] In one possible implementation, the concentration of calcium ions in the calcium-containing solution is 1-2 mol / L.
[0013] In one possible implementation, the mixing time of the carrier and the pore-forming agent is 30 to 40 minutes.
[0014] In one possible implementation, the calcium-based porous material is cylindrical in shape, has a diameter of 40-60 mm, and a purification efficiency of 92.5-99%.
[0015] The technical solution adopted in this invention can achieve the following beneficial effects: This invention provides a method for preparing a calcium-based porous material for adsorbing gaseous RuO4. The method includes: mixing a carrier and a pore-forming agent to form a mixed powder; adding water and an additive to the mixed powder and aging it for 20-24 hours to form a slurry; extruding the slurry into a porous material using an extruder; drying the porous material at 80-120°C for 5-12 hours; and calcining it at 400-1300°C for 3-8 hours; immersing the calcined porous material in a calcium-containing solution to load calcium ions onto the porous material, thus obtaining a calcium-based porous material for adsorbing gaseous RuO4. This calcium-based porous material is a novel porous material capable of irreversibly adsorbing gaseous RuO4, exhibiting a large adsorption capacity and a purification efficiency of 92.5-99%, which can meet the needs of nuclear industry applications. Attached Figure Description
[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below, forming part of the present invention. The illustrative embodiments of the present invention and their descriptions explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings: Figure 1 The image shown is an X-ray diffraction pattern of a calcium-containing solution loaded onto an adsorbent material according to an embodiment of this application. Detailed Implementation
[0017] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.
[0018] Example 1 Weigh out 50g of cordierite powder and 10g of starch, mix them together, and put them into a ball mill mixer to grind for 30 minutes to obtain a mixed powder; The ground powder was mixed with 7g water, 2g ethanol and 2g isopropanol, and then mechanically stirred and aged in a ball mill for 24 hours to form a mud. The aged mud is placed into the mold of the extruder and extruded into a cylindrical porous material. The extrusion pressure is 22MPa, the diameter of the porous material is 50mm, and the cross-section of the porous material is a honeycomb structure composed of several square honeycomb holes. The side length of the honeycomb hole is 4mm, and the wall thickness between the honeycomb holes is 1mm. The extruded porous material is placed in an oven and dried at 100°C for 10 hours. Then it is placed in a muffle furnace for high-temperature calcination. In the muffle furnace, the temperature is first increased to 400°C at a rate of 5°C / min and calcined for 30 minutes. Then the temperature is increased to 800°C at a rate of 5°C / min and calcined for 30 minutes. Finally, the temperature is increased to 1200°C at a rate of 3°C / min and calcined for 2 hours.
[0019] A calcium chloride solution with a calcium ion concentration of 1 mol / L was prepared. 50g of the calcined porous material was placed in 500 mL of the calcium chloride solution and then immersed at 40℃ for 6 hours. After being removed, it was placed in a drying oven and dried at 110℃ for 24 hours to obtain a calcium-based porous material with a specific surface area of 257 m² / g.
[0020] The RuO4 purification efficiency of the prepared calcium-based porous material was determined: a quartz glass tube was placed on a two-section tube furnace for testing. The quartz glass tube consisted of detachable sections 1, 2, 3, 4, and 5. First, ruthenium powder was placed in a quartz boat, which was then placed into the second section of the quartz glass tube. The prepared calcium-based porous material was then placed into the fourth section of the quartz glass tube. Both ends of the calcium-based porous material were sealed and compacted with quartz wool. The first section of the quartz glass tube was then... The second, third, fourth, and fifth sections are assembled together using ground joints. The second section of the quartz glass tube is placed upstream of the tube furnace, and the fourth section is placed downstream. A pure oxygen atmosphere is introduced into the inlet end of the first end of the quartz glass tube. The upstream end of the tube furnace is heated to 500°C at a heating rate of 10°C / min, and the downstream end is heated to 400°C at a heating rate of 10°C / min. The high-temperature heating converts the metallic ruthenium powder into gaseous RuO4, and is maintained for 6 hours. After the experiment, the weight loss of RuO2 powder and the weight gain of calcium-based porous material were weighed. The purification efficiency of RuO4 was calculated according to the purification efficiency formula η=(m3~m1) / (m2~m0)×100%, where m3 is the total weight of the calcium-based porous material and the fourth quartz glass tube after volatilization; m1 is the total weight of the calcium-based porous material and the fourth quartz glass tube before volatilization; m2 is the total weight of the quartz boat and ruthenium powder before volatilization; and m0 is the total weight of the quartz boat and ruthenium powder after volatilization. The calculated purification efficiency of the calcium-based porous material was 95.8%.
[0021] Example 2 The implementation method of Example 2 is the same as that of Example 1, except that: Replacing 10g of starch with 6g of fly ash, the calcium-based porous material prepared has a specific surface area of 185m² / g. The purification efficiency of the calcium-based porous material is calculated to be 92.5%.
[0022] Example 3 The implementation method of Example 3 is the same as that of Example 1, except that: Replacing 10g of starch with 10g of polystyrene microspheres, the calcium-based porous material prepared has a specific surface area of 294m² / g. The purification efficiency of the calcium-based porous material is calculated to be 99%.
[0023] Example 4 The implementation method of Example 4 is the same as that of Example 1, except that: A 1 mol / L calcium sulfate solution was prepared. 50 g of the adsorbent material was placed in 500 mL of calcium sulfate solution and then immersed at 40 °C for 6 h. After removal, it was placed in a drying oven and dried at 110 °C for 24 h to obtain a calcium-based porous material. The specific surface area of the prepared calcium-based porous material was 254 m² / g. The purification efficiency of the calcium-based porous material was calculated to be 95.2%.
[0024] Example 5 The implementation method of Example 5 is the same as that of Example 1, except that: A 1 mol / L calcium hypochlorite solution was prepared. 50 g of the adsorbent material was placed in 500 mL of calcium hypochlorite solution and then immersed at 40 °C for 6 h. After removal, it was placed in a drying oven and dried at 110 °C for 24 h to obtain a calcium-based porous material. The specific surface area of the prepared calcium-based porous material was 257 m² / g. The purification efficiency of the calcium-based porous material was calculated to be 90.5%.
[0025] Example 6 The implementation method of Example 6 is the same as that of Example 1, except that: 50g of cordierite powder and 5g of starch were added at a mass ratio of 10:1. The specific surface area of the calcium-based porous material prepared was 197m² / g. The purification efficiency of the calcium-based porous material was calculated to be 94%.
[0026] Example 7 The implementation method of Example 7 is the same as that of Example 1, except that: 50g of cordierite powder and 3.3g of starch were added in a mass ratio of 15:1 to prepare a calcium-based porous material with a specific surface area of 140mm² / g. The purification efficiency of the calcium-based porous material was calculated to be 90.7%.
[0027] Example 8 The implementation method of Example 8 is the same as that of Example 1, except that: A 1 mol / L calcium chloride solution was prepared. 50 g of the adsorbent material was placed in 500 mL of calcium chloride solution and then immersed at 60 °C for 6 h. After removal, it was placed in a drying oven and dried at 110 °C for 24 h to obtain a calcium-based porous material. The specific surface area of the prepared calcium-based porous material was 255 m² / g. The purification efficiency of the calcium-based porous material was calculated to be 96.5%.
[0028] Example 9 The implementation method of Example 9 is the same as that of Example 1, except that: A 1 mol / L calcium chloride solution was prepared. 50 g of the adsorbent material was placed in 500 mL of calcium chloride solution and then immersed at 80 °C for 6 h. After removal, it was placed in a drying oven and dried at 110 °C for 24 h to obtain a calcium-based porous material. The specific surface area of the prepared calcium-based porous material was 260 m² / g. The purification efficiency of the calcium-based porous material was calculated to be 97.2%.
[0029] Table 1. Component list of Examples 1-9
[0030] Table 2. Experimental results of Examples 1-9
[0031] X-ray diffraction was performed on the calcium-based porous materials prepared in Examples 1 to 9. Calcium compounds were loaded onto the porous materials, and the diffraction peaks of the calcium compounds were generally around 30°. Figure 1 As shown, the calcium-based porous materials prepared in Examples 1-9 all contain calcium compounds. As can be seen from Table 1, the calcium-based porous materials prepared by the preparation method of the present invention can be used as purification and capture materials for radioactive gaseous Ru in spent fuel reprocessing plants, or in other non-nuclear fields where gaseous volatile RuO4 may be generated. When the carrier is cordierite powder, the pore-forming agent is polystyrene microspheres, the calcium-containing solution is calcium chloride solution, the calcium ion impregnation temperature is 40°C, and the mass ratio of carrier to pore-forming agent is 5:1, the specific surface area and purification efficiency of the prepared calcium-based porous material are the highest, with a specific surface area of 294 m² / g and a purification efficiency of 99%.
[0032] When starch or fly ash is used as the pore-forming agent, the purification efficiencies of the prepared adsorbents are 95.8% and 92.6%, respectively, which are slightly lower than those using polystyrene microspheres as the pore-forming agent. When the ratio of carrier to pore-forming agent is 10:1 or 15:1, the purification efficiencies are 94% and 90.7%, respectively, indicating that the purification efficiency gradually decreases with increasing carrier content. When the calcium ion impregnation temperature is 60℃ and 80℃, the purification efficiencies are 96.5% and 97.2%, respectively, showing that the purification efficiency gradually increases with increasing calcium ion impregnation temperature.
[0033] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications or equivalent substitutions made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A method for preparing a calcium-based porous material that adsorbs gaseous RuO4, characterized in that, include: The carrier and pore-forming agent are stirred evenly to form a mixed powder; Add water and additives to the mixed powder, knead and age for 20-24 hours to form a slurry; The slurry is put into an extruder and extruded to obtain a porous material. The porous material is then dried at 80~120℃ for 5~12 hours, followed by calcination at 400℃~1200℃ for 3~8 hours. The calcined porous material is immersed in a calcium-containing solution to load calcium ions onto the porous material, thus obtaining a calcium-based porous material for adsorbing gaseous RuO4.
2. The preparation method according to claim 1, characterized in that, The mass ratio of the carrier to the pore-forming agent is 5-10; and / or, the mass ratio of the carrier to water is 7.14-10; and / or, the mass ratio of the carrier to the additive is 8.3-25.
3. The preparation method according to claim 2, characterized in that, The carrier is cordierite powder; and / or, the pore-forming agent is any one of polystyrene microspheres, starch, and fly ash; and / or, the additive is a mixed solution of ethanol and glycerol.
4. The preparation method according to claim 1, characterized in that, The extrusion pressure of the extruder is 20~50 MPa.
5. The preparation method according to claim 1, characterized in that, The roasting process is as follows: in a muffle furnace, the temperature is increased to 400℃~500℃ at a heating rate of 5℃ / min, roasted for 30 minutes, then increased to 800℃ at a heating rate of 5℃ / min, roasted for 30 minutes, and then increased to 1200℃ at a heating rate of 5℃ / min, roasted for 2 hours.
6. The preparation method according to claim 1, characterized in that, The calcined porous material is immersed in a calcium-containing solution at a temperature of 40°C to 80°C for 4 to 8 hours. After immersion, the porous material is removed and dried at 100 to 120°C for 22 to 26 hours.
7. The preparation method according to claim 1, characterized in that, The calcium-containing solution is at least one of calcium chloride, calcium sulfate, and calcium hypochlorite.
8. The preparation method according to claim 7, characterized in that, The concentration of calcium ions in the calcium-containing solution is 1~2 mol / L.
9. The preparation method according to claim 1, characterized in that, The stirring time for the carrier and pore-forming agent is 30-40 minutes.
10. The preparation method according to claim 1, characterized in that, The calcium-based porous material is cylindrical in shape, with a diameter of 40-60 mm, and a purification efficiency of 92.5-99%.