A bismuth-based bimetallic aerogel adsorbent and its preparation method and application

Abstract

The present invention discloses a bismuth-based bimetallic aerogel adsorbent and a preparation method and application thereof, including: forming a bismuth-based bimetallic aerogel adsorbent having a three-dimensional mesh porous structure by co-solution of bismuth and transition metal; the transition metal is one of nickel, palladium and silver. The present invention constructs a bismuth-based bimetallic aerogel material having a three-dimensional porous structure, and on the premise of maintaining the high adsorption performance of the bismuth-based material for radioactive iodine, synergistically utilizes the physical adsorption enrichment effect of the three-dimensional porous structure of the aerogel, and improves the thermal stability of the bismuth aerogel, so that the bismuth-based bimetallic aerogel adsorbent has excellent selectivity and efficient removal ability for gaseous radioactive iodine ions; at the same time, the preparation process of the present invention is simple and efficient.

Description

Technical Field

[0001] The present invention belongs to the technical field of bismuth-based materials and adsorption materials for treating radioactive waste gas in the process of spent fuel post-processing. More specifically, the present invention relates to a bismuth-based bimetallic aerogel adsorbent and a preparation method and application thereof. Background Art

[0002] As one of the fission elements of nuclear fission, radioactive iodine (mainly 129 I and 131 I) High yield, strong radioactivity, easy to volatilize, migrate, and bioaccumulate, which can cause great harm to the environment and human body, especially 129 Its half-life is more than 15 million years. Once it leaks into the environment, it can cause almost permanent radioactive contamination. The toxicity index (hazards available index, HA) of key radionuclides under geological disposal conditions is as follows: 129 The HA value of I reaches 11.1, which is 239 Pu(HA=9.6) and 241 Am (HA = 7.1) is higher than that of other radionuclides, ranking first among all the evaluated nuclides. In the classification of radioactive waste jointly released by the Ministry of Environmental Protection, the Ministry of Industry and Information Technology and the State Administration of Science, Technology and Industry for National Defense in 2017, 129 I is one of the most stringent nuclides in low-level waste. Therefore, how to efficiently and safely adsorb and separate radioactive nuclides of iodine under extreme environmental conditions is a technical problem in spent fuel reprocessing and an important research topic in environmental radiochemistry. Summary of the invention

[0003] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0004] In order to achieve these purposes and other advantages according to the present invention, a bismuth-based bimetallic aerogel adsorbent for removing radioactive iodine is provided, comprising: forming a bismuth-based bimetallic aerogel adsorbent having a three-dimensional network porous structure by forming a co-sol of bismuth and a transition metal.

[0005] Preferably, the transition metal is one of nickel, palladium and silver.

[0006] A method for preparing a bismuth-based bimetallic aerogel adsorbent for removing radioactive iodine, wherein the transition metal is nickel, and the bismuth-based bimetallic aerogel adsorbent is a bismuth-nickel bimetallic aerogel adsorbent, and the preparation method comprises the following steps:

[0007] Step 1, adding sodium borohydride into water to fully dissolve to obtain a sodium borohydride solution, adding bismuth chloride into methanol to fully dissolve to obtain a bismuth chloride solution, and adding nickel chloride pentahydrate powder into methanol to fully dissolve to obtain a nickel chloride solution;

[0008] Step 2: adding the sodium borohydride solution obtained in step 1 to the nickel chloride solution, the solution reacts violently and turns black, and then quickly adding the bismuth chloride solution to continue the reaction;

[0009] Step 3: The solution obtained by the reaction in step 2 is allowed to stand at room temperature, and a black bismuth-nickel hydrogel is generated at the bottom of the beaker. The waste liquid on the upper layer of the beaker is poured out to obtain the bismuth-nickel hydrogel, which is washed with deionized water and ethanol for multiple times. The bismuth-nickel hydrogel obtained by filtration is placed in a freeze dryer for drying, and after drying, a bismuth-nickel bimetallic aerogel adsorbent is obtained.

[0010] Preferably, in the step 1, the concentrations of the sodium borohydride solution, bismuth chloride solution and nickel chloride solution are 0.1M, 0.06M and 0.1M respectively, the molar ratio of sodium borohydride, bismuth chloride and nickel chloride is 5:3:5, the water is deionized water; and the methanol is anhydrous methanol with a mass fraction of 99.8%.

[0011] Preferably, in step three, the standing time at room temperature is 5 to 10 hours, and the drying time in the freeze dryer is 24 to 72 hours.

[0012] Preferably, the process of step 2 is replaced by: placing the nickel chloride solution on a constant temperature magnetic stirrer for heat preservation and stirring, adding the sodium borohydride solution and continuing to stir, reacting sufficiently until the solution turns black, and then quickly adding the bismuth chloride solution and continuing to stir.

[0013] Preferably, the rotation speed of the constant temperature magnetic stirrer is 800 r / min to 1200 r / min, the insulation temperature is 40° C. to 60° C., and the stirring time after adding the nickel chloride solution is 1 to 3 minutes.

[0014] A method for preparing a bismuth-based bimetallic aerogel adsorbent for removing radioactive iodine, wherein the transition metal is silver, and the bismuth-based bimetallic aerogel adsorbent is a bismuth-silver bimetallic aerogel adsorbent, and the preparation method comprises the following steps:

[0015] Step 1, adding sodium borohydride to deionized water and stirring to fully dissolve to obtain a sodium borohydride solution; adding bismuth chloride powder to anhydrous methanol and fully dissolving to obtain a bismuth chloride solution; adding silver nitrate powder to anhydrous methanol and stirring to fully dissolve to obtain a silver nitrate solution; wherein the concentration of the sodium borohydride solution is 0.1M, the concentration of the bismuth chloride solution is 0.1M, and the concentration of the silver nitrate solution is 0.02M; the molar ratio of sodium borohydride, bismuth chloride powder and silver nitrate powder is 5:5:1;

[0016] Step 2: Add the sodium borohydride solution obtained in step 1 to the silver nitrate solution and place it on a constant temperature magnetic stirrer, stir at a temperature of 40° C. to 60° C. and a speed of 800 r / min to 1200 r / min to allow the mixed solution to react fully, then quickly add the bismuth chloride solution and continue stirring for 1 min to 3 min, and let the resulting solution stand at room temperature for 8 h to 10 h, and the solution precipitates to produce a black bismuth-silver bimetallic gel, and the upper layer of the solution is poured off to leave the bismuth-silver gel, which is washed 2 to 3 times with deionized water and ethanol;

[0017] Step 3: Place the bismuth-silver bimetallic gel material washed in step 3 into a freeze dryer for freeze drying for 48 hours to finally obtain a bismuth-silver bimetallic aerogel material.

[0018] A method for preparing a bismuth-based bimetallic aerogel adsorbent for removing radioactive iodine, wherein the transition metal is palladium, and the bismuth-based bimetallic aerogel adsorbent is a bismuth-palladium bimetallic aerogel adsorbent, and the preparation method comprises the following steps:

[0019] Step 1, adding palladium chloride powder to hydrochloric acid with a concentration of and stirring to fully dissolve to obtain a tetrachloropalladic acid solution, adding bismuth chloride powder to anhydrous methanol and stirring to fully dissolve, and dissolving sodium borohydride solution in deionized water and stirring to fully dissolve; wherein the concentration of the hydrochloric acid is 10mM, the molar ratio of palladium chloride powder, bismuth chloride powder, and sodium borohydride is 1:4:40, the concentration of tetrachloropalladic acid solution is 0.01M, the concentration of bismuth chloride solution is 0.05M, and the concentration of sodium borohydride solution is 2M;

[0020] Step 2, adding the tetrachloropalladic acid solution obtained in the reaction of step 1 to the bismuth chloride solution and placing it on a constant temperature magnetic stirrer, stirring and mixing at 40°C to 60°C and at a speed of 800r / min to 1200r / min, then adding the sodium borohydride solution and continuing to stir for 5 minutes, and keeping the resulting solution at 60°C for 6 hours, a black bismuth-palladium bimetallic gel is generated at the bottom of the solution, and the upper layer of the solution is poured off to leave the bismuth-palladium gel, which is washed 2 to 3 times with deionized water and ethanol;

[0021] Step 3: Place the bismuth-palladium bimetallic gel material washed in step 2 into a freeze dryer for freeze drying for 48 hours to finally obtain a bismuth-palladium bimetallic aerogel material.

[0022] The invention discloses an application of a bismuth-based bimetallic aerogel adsorbent for removing radioactive iodine. The bismuth-based bimetallic aerogel adsorbent is applied to the adsorption and removal of radioactive iodine.

[0023] In order to improve the adsorption capacity of the bismuth-nickel bimetallic aerogel adsorbent for radioactive iodine, in step 3, after a black bismuth-nickel hydrogel is generated at the bottom of the beaker, a layered alumina loaded with silver is added for ultrasonic oscillation, the ultrasonic frequency is 50-90 kHz, and the ultrasonic time is 20-40 minutes. Subsequently, the waste liquid on the upper layer of the beaker is poured out to obtain the bismuth-nickel hydrogel, which is washed with deionized water and ethanol for 3 times, and the filtered bismuth-nickel hydrogel is placed in a freeze dryer for drying. After drying, the bismuth-nickel hydrogel is heat-treated at 200-400° C. for 1-6 hours to enhance the stability of the combination of the layered alumina and the bismuth-nickel hydrogel, so as to obtain a bismuth-nickel bimetallic aerogel adsorbent; wherein the mass ratio of the layered alumina to the nickel chloride pentahydrate is 1-3:15-20, and the preparation method of the layered alumina loaded with silver comprises:

[0024] S11. Weigh aluminum hydroxide powder with a particle size distribution of 2 to 10 μm, add the aluminum hydroxide powder to deionized water, add sodium dodecyl sulfate, and ultrasonically disperse at a frequency of 60 to 90 kHz for 20 to 50 min to obtain a suspension; filter the suspension, wash, and dry to obtain aluminum hydroxide solid, place the aluminum hydroxide solid in a calcining furnace for calcination at a temperature of 800 to 1300° C. for 1 to 3 hours to obtain layered aluminum oxide; wherein the mass volume ratio of aluminum hydroxide powder, deionized water, and sodium dodecyl sulfate is 5 to 15 g: 50 to 200 mL: 0.1 to 2 g;

[0025] S12, immersing the layered aluminum oxide in a silver nitrate-methanol solution, wherein the concentration of silver nitrate in the silver nitrate-methanol solution is 0.1-0.5 mol / L, and the mass ratio of the layered aluminum oxide to silver nitrate is 20-50:1-3; evaporating and removing methanol from the silver nitrate-methanol solution, transferring the aluminum oxide to a vacuum reaction chamber, and evacuating to 2.2×10 -6 Pa, H2 is introduced into the vacuum reaction chamber at a flow rate of 20 to 45 sccm, and a reduction reaction is carried out at a temperature of 120°C to 180°C to reduce the surface of the layered alumina to achieve silver loading, thereby obtaining layered alumina loaded with silver.

[0026] The present invention at least includes the following beneficial effects: the present invention synthesizes a bismuth-based bimetallic aerogel material having a three-dimensional mesh porous structure by a sol-gel method. Due to the synergistic effect of physical adsorption on the surface and pores of the three-dimensional mesh porous structure and chemical adsorption of metal bismuth, according to the HSAB soft-hard acid-base theory, it can be known that bismuth has good affinity for iodine, so that the bismuth-based bimetallic aerogel adsorbent has excellent selectivity and high efficiency in removing radioactive iodine in the gas. In addition, metals (such as silver and palladium) with adsorption activity for methyl iodide can be selected to synthesize the bimetallic aerogel with bismuth metal, so that radioactive iodine and radioactive methyl iodide can be simultaneously adsorbed and separated. At the same time, the material preparation process is simple and efficient.

[0027] The present invention also uses layered alumina to load silver, and then combines the layered alumina loaded with silver with bismuth nickel hydrogel, and then dries and heat-treats to obtain a bismuth nickel bimetallic aerogel adsorbent. The above method is used to achieve uniform loading of silver by using layered alumina with a large specific surface area, and then combines it with the bismuth nickel hydrogel and then undergoes heat treatment to obtain a bismuth nickel bimetallic aerogel adsorbent. The three-dimensional mesh porous structure of the bismuth nickel bimetallic aerogel adsorbent after drying is utilized to increase the adsorption surface area of ​​the bismuth nickel bimetallic aerogel, and further improve the adsorption capacity of the bismuth nickel bimetallic aerogel for iodine.

[0028] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a SEM image of the bismuth-nickel bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 1 of the present invention;

[0030] Figure 2 This is an XRD image of the bismuth-nickel bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 1 of the present invention;

[0031] Figure 3 This is a TAG diagram of the bismuth-nickel bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 1 of the present invention;

[0032] Figure 4 This is an adsorption kinetic diagram of the bismuth-nickel bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 1 of the present invention;

[0033] Figure 5 This is a SEM image of the bismuth-silver bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 2 of the present invention;

[0034] Figure 6 This is an XRD image of the bismuth-silver bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 2 of the present invention;

[0035] Figure 7 This is an adsorption kinetic diagram of the bismuth-silver bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 2 of the present invention;

[0036] Figure 8 This is a SEM image of the bismuth-palladium bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 3 of the present invention;

[0037] Fig. 9This is a TGA image of the bismuth-palladium bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 3 of the present invention;

[0038] Fig.10 This is an adsorption kinetic diagram of the bismuth-palladium bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0040] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0041] Embodiment 1:

[0042] A method for preparing a bismuth-nickel bimetallic aerogel adsorbent for removing radioactive iodine comprises the following steps:

[0043] Step 1: Prepare the solution

[0044] Add 189 mg of sodium borohydride to 50 mL of deionized water and stir to fully dissolve, add 1097.5 mg of nickel chloride pentahydrate powder to 50 mL of anhydrous methanol and stir to dissolve, and add 945.6 mg of bismuth chloride powder to 50 mL of anhydrous methanol and fully dissolve;

[0045] Step 2: Synthesize gel

[0046] Add sodium borohydride solution to nickel chloride solution and place it on a constant temperature magnetic stirrer. Stir at 60°C and 1200 r / min to allow the mixed solution to react fully. Then quickly add bismuth chloride solution and continue stirring for 3 minutes. The resulting solution is allowed to stand at room temperature for 10 hours. The solution precipitates to produce black bismuth-nickel bimetallic gel. Pour off the upper solution and leave the bismuth-nickel gel, which is washed three times with deionized water and ethanol.

[0047] Step 3: Freeze Drying

[0048] The bismuth-nickel bimetallic gel material washed in step 2 was placed in a freeze dryer for freeze drying for 48 hours to finally obtain a bismuth-nickel bimetallic aerogel material.

[0049] Embodiment 2:

[0050] A method for preparing a bismuth-silver bimetallic aerogel adsorbent for removing radioactive iodine comprises the following steps:

[0051] Step 1: Prepare the solution

[0052] 189 mg of sodium borohydride was added to 50 mL of deionized water and stirred to fully dissolve to obtain a sodium borohydride solution; 1576 mg of bismuth chloride powder was added to 50 mL of anhydrous methanol and fully dissolved to obtain a bismuth chloride solution; 169.8 mg of silver nitrate powder was added to 50 mL of anhydrous methanol and stirred to fully dissolve to obtain a silver nitrate solution;

[0053] Step 2: Synthesize gel

[0054] The sodium borohydride solution obtained in step 1 is added to the silver nitrate solution and placed on a constant temperature magnetic stirrer. The mixed solution is stirred at 60°C and 1200 r / min to allow the mixed solution to react fully. The bismuth chloride solution is then quickly added and stirred for 3 minutes. The resulting solution is allowed to stand at room temperature for 10 hours. The solution precipitates to produce a black bismuth-silver bimetallic gel. The upper layer of the solution is discarded, leaving the bismuth-silver gel, which is washed three times with deionized water and ethanol.

[0055] Step 3: Freeze Drying

[0056] The bismuth-silver bimetallic gel material washed in step 2 was placed in a freeze dryer for freeze drying for 48 hours to finally obtain a bismuth-silver bimetallic aerogel material.

[0057] Embodiment 3:

[0058] A method for preparing a bismuth-palladium bimetallic aerogel adsorbent for removing radioactive iodine comprises the following steps:

[0059] Step 1: Prepare the solution

[0060] 44.5 mg of palladium chloride powder was added to 25 mL of 10 mM hydrochloric acid and stirred to fully dissolve to obtain a tetrachloropalladic acid solution. 788 mg of bismuth chloride powder was added to 50 mL of anhydrous methanol and stirred to fully dissolve. 378 mg of sodium borohydride solution was dissolved in 5 mL of deionized water and stirred to fully dissolve.

[0061] Step 2: Synthesize gel

[0062] The tetrachloropalladic acid solution obtained in step 1 is added to the bismuth chloride solution and placed on a constant temperature magnetic stirrer. The mixture is stirred at 60°C and 1200 r / min to be uniformly mixed. Then, the sodium borohydride solution is added and stirring is continued for 5 minutes. The obtained solution is kept at 60°C for 6 hours. A black bismuth-palladium bimetallic gel is generated at the bottom of the solution. The upper solution is poured off to leave the bismuth-palladium gel, which is washed three times with deionized water and ethanol.

[0063] Step 3: Freeze Drying

[0064] The bismuth-palladium bimetallic gel material washed in step 2 was placed in a freeze dryer for freeze drying for 48 hours to finally obtain a bismuth-palladium bimetallic aerogel material.

[0065] Example 4

[0066] The present embodiment provides a method for preparing a bismuth-nickel bimetallic aerogel adsorbent for removing radioactive iodine, wherein step 1 is the same as that of embodiment 1, except that in step 2, after the solution precipitates to produce a black bismuth-nickel bimetallic gel, 55 mg of silver-loaded layered alumina is added for ultrasonic oscillation, the ultrasonic frequency is 60 kHz, and the ultrasonic time is 40 min. Subsequently, the waste liquid on the upper layer of the beaker is poured out to obtain a bismuth-nickel hydrogel, which is washed with deionized water and ethanol for 3 times respectively, and the filtered bismuth-nickel hydrogel is placed in a freeze dryer for drying, and after drying, heat-treated at 200° C. for 5 h to enhance the stability of the combination of the layered alumina and the bismuth-nickel hydrogel, thereby obtaining a bismuth-nickel bimetallic aerogel adsorbent; wherein the method for preparing the silver-loaded layered alumina comprises:

[0067] S11, weighing 10g of aluminum hydroxide powder with a particle size distribution of 2 to 10μm, adding the aluminum hydroxide powder to 200mL of deionized water, adding 0.5g of sodium dodecyl sulfate, and ultrasonically dispersing at a frequency of 60kHz for 20min to obtain a suspension; filtering the suspension, washing, and drying to obtain aluminum hydroxide solid, placing the aluminum hydroxide solid in a calcining furnace for calcination at a temperature of 950°C for 2h to obtain layered aluminum oxide;

[0068] S12, immerse 34g of layered aluminum oxide in 100mL of silver nitrate-methanol solution, the concentration of silver nitrate in the silver nitrate-methanol solution is 0.1mol / L; evaporate the methanol in the silver nitrate-methanol solution, transfer the aluminum oxide to a vacuum reaction chamber, and evacuate to 2.2×10 -6 Pa, H2 was introduced into the vacuum reaction chamber at a flow rate of 30sccm, and a reduction reaction was carried out at a temperature of 180°C to reduce the surface of the layered alumina to achieve silver loading, thereby obtaining layered alumina loaded with silver.

[0069] Example 5

[0070] The present embodiment provides a method for preparing a bismuth-nickel bimetallic aerogel adsorbent for removing radioactive iodine, wherein step 1 is the same as that of embodiment 1, except that in step 2, after the solution precipitates to produce a black bismuth-nickel bimetallic gel, 70 mg of silver-loaded layered alumina is added for ultrasonic oscillation, the ultrasonic frequency is 80 kHz, and the ultrasonic time is 20 min. Subsequently, the waste liquid on the upper layer of the beaker is poured out to obtain a bismuth-nickel hydrogel, which is washed with deionized water and ethanol for multiple times, and the filtered bismuth-nickel hydrogel is placed in a freeze dryer for drying, and after drying, heat-treated at 400° C. for 2 h to enhance the stability of the combination of the layered alumina and the bismuth-nickel hydrogel, thereby obtaining a bismuth-nickel bimetallic aerogel adsorbent; wherein the method for preparing the silver-loaded layered alumina comprises:

[0071] S11, weighing 30g of aluminum hydroxide powder with a particle size distribution of 2 to 10μm, adding the aluminum hydroxide powder to 250mL of deionized water, adding 1g of sodium dodecyl sulfate, and ultrasonically dispersing at a frequency of 60kHz to obtain a suspension; filtering the suspension, washing, and drying to obtain aluminum hydroxide solid, placing the aluminum hydroxide solid in a calcining furnace for calcination at a temperature of 1000°C for 1h to obtain layered aluminum oxide;

[0072] S12, immerse 34g of layered aluminum oxide in 200mL of 0.1mol / L silver nitrate-methanol solution; evaporate the methanol in the silver nitrate-methanol solution, transfer the aluminum oxide to a vacuum reaction chamber, and evacuate to 2.2×10 - 6 Pa, H2 was introduced into the vacuum reaction chamber at a flow rate of 45 sccm, and a reduction reaction was carried out at a temperature of 180°C to reduce the surface of the layered alumina to achieve silver loading, thereby obtaining layered alumina loaded with silver.

[0073] Figure 1 This is a scanning electron microscope (SEM) image of the bismuth-nickel bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 1. Figure 1 It can be seen that the freeze-dried bismuth-nickel bimetallic aerogel has a three-dimensional network porous structure formed by stacking nanoparticles.

[0074] Figure 2 is the XRD pattern of the bismuth-nickel bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 1, as shown in Figure 2 The characteristic peaks of the X-ray diffraction spectrum of the bismuth-nickel bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 1 are consistent with the characteristic peaks of the standard card of bismuth and silver, indicating that the prepared bismuth-nickel bimetallic aerogel adsorbent for removing radioactive iodine contains two phases of bismuth and nickel.

[0075] Figure 3is the TGA diagram of the bismuth-nickel bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 1, as shown in Figure 3 As shown in the temperature range of 100°C to 800°C, the weight loss rate of the bismuth-nickel bimetallic aerogel adsorbent prepared in Example 1 is significantly lower than that of the bismuth metal aerogel, indicating that the bismuth-nickel bimetallic aerogel prepared in Example 1 has better thermal stability.

[0076] Figure 4 is the adsorption kinetics diagram of the bismuth-nickel bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 1, as shown in Figure 4 As shown, the adsorption of iodine by the bismuth-nickel bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 1 (the specific implementation process is to put a certain amount of iodine into a 30mL glass bottle, and then take 25mg of the bismuth-nickel bimetallic aerogel adsorbent synthesized in Example 1 and place it in the conical filter paper on the top of the bottle and seal the glass bottle with a lid, and heat it to 75°C under ambient pressure to evaporate the iodine). The adsorption capacity of the sample for iodine increases with the increase of contact time, wherein in the 0-80min time period, the adsorption capacity rapidly increases to 1300mg / g, and then the adsorption capacity increases slowly, and the adsorption reaches equilibrium before 200min and the maximum adsorption capacity is 1350mg / g. The results of the adsorption kinetic model fitting analysis are more consistent with the quasi-second-order kinetic model, indicating that the process of iodine adsorption by the bismuth-nickel bimetallic aerogel adsorbent prepared in Example 1 is mainly controlled by the reaction rate. The bismuth-nickel bimetallic aerogel adsorbent prepared in Example 4 and Example 5 was added with layered alumina loaded with silver, and the adsorption capacity of iodine by the bismuth-nickel bimetallic aerogel of Example 4 and Example 5 was measured by the same method. The maximum adsorption capacity of iodine by the bismuth-nickel bimetallic aerogel of Example 4 and Example 5 reached 1590 mg / g and 1561 mg / g, respectively. Compared with 1350 mg / g of Example 1, the adsorption capacity of iodine by the bismuth-nickel bimetallic aerogel of Example 4 and Example 5 was significantly improved, indicating that the bismuth-nickel bimetallic aerogel of Example 4 and Example 5 has a stronger adsorption capacity for iodine.

[0077] Figure 5 This is a scanning electron microscope (SEM) image of the bismuth-silver bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 2. The bismuth-silver bimetallic aerogel prepared in Example 2 exhibits a typical three-dimensional porous network structure, which is formed by stacking and connecting bismuth nanorods to form a porous structure. Its surface features and grain boundaries are clearly visible in the high-resolution SEM image, and silver is distributed in the bismuth matrix in the form of particles.

[0078] Figure 6 : is the XRD spectrum of the bismuth-silver bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 2. Figure 6The X-ray diffraction characteristic peaks of the bismuth-silver bimetallic aerogel adsorbent prepared in Example 2 are basically consistent with the characteristic peaks of the standard cards of bismuth and silver, indicating that Example 2 successfully prepared the bismuth-silver bimetallic aerogel adsorbent.

[0079] Figure 7 2 is an adsorption kinetic diagram of the bismuth-silver bimetallic aerogel adsorbent prepared in Example 2 for removing radioactive iodine. Figure 7 The adsorption of iodine by the bismuth-silver bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 2 is shown (the specific implementation process is to put a certain amount of iodine into a 30 mL glass bottle, and then take 25 mg of the bismuth-silver bimetallic aerogel adsorbent synthesized in Example 2 and place it in the conical filter paper on the top of the bottle and seal the glass bottle with a lid, and heat it to 75°C under ambient pressure to evaporate the iodine). The adsorption capacity of the sample for iodine increases with the increase of contact time, and the adsorption amount increases rapidly with time before 5 hours to reach about 1300 mg / g, and then the adsorption capacity increases slowly, and gradually tends to stabilize at about 6 hours. The maximum adsorption capacity is 1360 mg / g. Through the kinetic model fitting analysis, it can be seen that the adsorption of iodine by the bismuth-silver bimetallic aerogel adsorbent material prepared in Example 3 is well fitted with both the pseudo-first-order kinetic model and the pseudo-second-order kinetic model (the correlation coefficients are R1 2 =0.98, R2 2 =0.93), indicating that the adsorption process is synergistically controlled by mass transfer and reaction rate.

[0080] Figure 8 is a scanning electron microscope (SEM) image of the bismuth-palladium bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 3, as shown in FIG. Figure 8 The bismuth-palladium bimetallic aerogel adsorbent prepared in Example 3 shows a typical three-dimensional porous structure formed by stacking and connecting nanoparticles.

[0081] Fig. 9 : is a thermogravimetric analysis (TGA) diagram of the bismuth-palladium bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 3. Fig. 9 As shown in FIG. 3 , the bismuth-palladium bimetallic aerogel adsorbent prepared in Example 3 has a mass loss of about 4.5% in the temperature range of 100 to 800°C, which is similar to Figure 1 Comparison of the TGA graphs of bismuth aerogels shows that bismuth palladium aerogels have better thermal stability. Even if the temperature continues to rise to 1000° C., the mass loss of the bismuth palladium bimetallic aerogel adsorbent prepared in Example 3 is only 10.79%.

[0082] Fig.10 is the adsorption kinetics diagram of the bismuth-palladium bimetallic aerogel adsorbent for removing radioactive iodine prepared in Example 3, as shown in Fig.10The adsorption of iodine by the bismuth palladium bimetallic aerogel adsorbent for removing radioactive iodine prepared in Case 3 shown in the figure (the specific implementation process is to put a certain amount of iodine into a 30mL glass bottle, and then take 25mg of the bismuth palladium bimetallic aerogel adsorbent synthesized in Example 3 and place it in the conical filter paper on the top of the bottle and seal the glass bottle with a lid, and keep it at 75°C under ambient pressure to evaporate the iodine). The adsorption capacity of the sample for iodine increases with the increase of contact time. In the first 8 hours, the adsorption capacity of the material for iodine rapidly increases to about 1250mg / g, and then the adsorption capacity slowly increases to reach adsorption equilibrium in about 24 hours. The maximum adsorption capacity is 1455mg / g. The results of the kinetic model fitting analysis are more consistent with the quasi-second-order kinetic model, indicating that the iodine adsorption process of the bismuth palladium bimetallic aerogel adsorbent prepared in Example 3 is mainly controlled by the reaction rate.

[0083] The bismuth-based bimetallic aerogel adsorbent for removing radioactive iodine prepared in Examples 1 to 5 and the preparation method thereof, by constructing a bismuth-based bimetallic aerogel material with a three-dimensional porous structure, while maintaining the high adsorption performance of the bismuth-based material for radioactive iodine, synergistically utilizing the physical adsorption enrichment effect of the three-dimensional porous structure of the aerogel, and improving the thermal stability of the bismuth aerogel, the bismuth-based bimetallic aerogel adsorbent has excellent selectivity and efficient removal ability for gaseous radioactive iodine ions. At the same time, the preparation process is simple and efficient.

[0084] The number of devices and processing scales described here are used to simplify the description of the present invention. Applications, modifications and variations of the present invention will be obvious to those skilled in the art.

[0085] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. An application of a bismuth-based bimetallic aerogel adsorbent, characterized in that: The bismuth-based bimetallic aerogel adsorbent is used for adsorption and removal of radioactive iodine; The preparation method of the bismuth-based bimetallic aerogel adsorbent specifically comprises: Step 1: adding sodium borohydride solution to nickel chloride solution, the solution undergoes a violent reaction and turns black, and then quickly adding bismuth chloride solution to continue the reaction; Step 2: The solution obtained by the reaction in step 1 is allowed to stand at room temperature, a black bismuth-nickel hydrogel is generated at the bottom of the beaker, and silver-loaded layered alumina is added and ultrasonically oscillated at 50-90 kHz for 20-40 minutes, and the waste liquid on the upper layer of the beaker is poured out to obtain the bismuth-nickel hydrogel, which is washed with deionized water and ethanol for 3 times, and the filtered bismuth-nickel hydrogel is placed in a freeze dryer for drying, and heat-treated at 200-400° C. for 1-6 hours to obtain a bismuth-nickel bimetallic aerogel adsorbent; the mass ratio of the silver-loaded layered alumina to the nickel chloride solution solute nickel chloride pentahydrate is 1-3:15-20, and the preparation method of the silver-loaded layered alumina comprises: S11. Weigh aluminum hydroxide powder with a particle size distribution of 2-10 μm, add the aluminum hydroxide powder to deionized water, add sodium dodecyl sulfate, and perform ultrasonic dispersion at 60-90 kHz for 20-50 min to obtain a suspension; filter the suspension, wash, and dry to obtain aluminum hydroxide solid, place the aluminum hydroxide solid in a calcining furnace and calcine at 800-1300° C. for 1-3 h to obtain layered aluminum oxide; wherein the mass volume ratio of aluminum hydroxide powder, deionized water, and sodium dodecyl sulfate is 5-15 g:50-200 mL:0.1-2 g; S12, immersing the layered aluminum oxide in a silver nitrate-methanol solution with a silver nitrate concentration of 0.1-0.5 mol / L, wherein the mass ratio of the layered aluminum oxide to the silver nitrate is 20-50:1-3; evaporating the methanol to remove the aluminum oxide, transferring the aluminum oxide to a vacuum reaction chamber, and evacuating the chamber to a temperature of 2.2×10 -6 Pa, H2 is introduced into the vacuum reaction chamber at a flow rate of 20-45 sccm, and a reduction reaction is carried out at 120°C-180°C to obtain layered alumina loaded with silver.

2. The use of the bismuth-based bimetallic aerogel adsorbent according to claim 1, characterized in that: Also includes: Sodium borohydride is added into water to dissolve to obtain a sodium borohydride solution, bismuth chloride is added into methanol to dissolve to obtain a bismuth chloride solution, and nickel chloride pentahydrate powder is added into methanol to dissolve to obtain a nickel chloride solution.

3. The use of the bismuth-based bimetallic aerogel adsorbent as claimed in claim 2, characterized in that: The concentrations of the sodium borohydride solution, bismuth chloride solution and nickel chloride solution are 0.1M, 0.06M and 0.1M respectively, the molar ratio of sodium borohydride, bismuth chloride and nickel chloride is 5:3:5, the water is deionized water; and the methanol is anhydrous methanol with a mass fraction of 99.8%.

4. The use of the bismuth-based bimetallic aerogel adsorbent according to claim 1, characterized in that: In the step 2, the standing time at room temperature is 5 to 10 hours, and the drying time in the freeze dryer is 24 to 72 hours.

5. The use of the bismuth-based bimetallic aerogel adsorbent according to claim 1, characterized in that: The process of step 1 is replaced by: placing the nickel chloride solution on a constant temperature magnetic stirrer and stirring it, adding the sodium borohydride solution and continuing to stir it, and after sufficient reaction until the solution turns black, quickly adding the bismuth chloride solution and continuing to stir it.

6. The use of the bismuth-based bimetallic aerogel adsorbent as claimed in claim 5, characterized in that: The rotation speed of the constant temperature magnetic stirrer is 800 r / min-1200 r / min, the insulation temperature is 40° C.-60° C., and the stirring time after adding the nickel chloride solution is 1-3 min.

7. An application of a bismuth-based bimetallic aerogel adsorbent, characterized in that: The bismuth-based bimetallic aerogel adsorbent is a bismuth-silver bimetallic aerogel adsorbent, which is used for adsorption and removal of radioactive iodine. The preparation method of the bismuth-silver bimetallic aerogel adsorbent comprises the following steps: Step 1, adding sodium borohydride to deionized water and stirring to fully dissolve to obtain a sodium borohydride solution; adding bismuth chloride powder to anhydrous methanol and fully dissolving to obtain a bismuth chloride solution; adding silver nitrate powder to anhydrous methanol and stirring to fully dissolve to obtain a silver nitrate solution; wherein the concentration of the sodium borohydride solution is 0.1M, the concentration of the bismuth chloride solution is 0.1M, and the concentration of the silver nitrate solution is 0.02M; the molar ratio of sodium borohydride, bismuth chloride powder and silver nitrate powder is 5:5:1; Step 2: Add the sodium borohydride solution obtained in step 1 to the silver nitrate solution and place it on a constant temperature magnetic stirrer, stir at a temperature of 40°C to 60°C and a speed of 800r / min to 1200r / min to allow the mixed solution to react fully, then quickly add the bismuth chloride solution and continue stirring for 1min to 3min, and let the resulting solution stand at room temperature for 8h to 10h, the solution precipitates to produce a black bismuth-silver bimetallic gel, pour off the upper solution to leave the bismuth-silver gel, and wash it 2 to 3 times with deionized water and ethanol; Step 3: Place the bismuth-silver bimetallic gel material washed in step 3 into a freeze dryer for freeze drying for 48 hours to finally obtain a bismuth-silver bimetallic aerogel material.

8. An application of a bismuth-based bimetallic aerogel adsorbent, characterized in that: The bismuth-based bimetallic aerogel adsorbent is a bismuth-palladium bimetallic aerogel adsorbent, which is used for adsorption and removal of radioactive iodine. The preparation method of the bismuth-palladium bimetallic aerogel adsorbent comprises the following steps: Step 1, adding palladium chloride powder to hydrochloric acid and stirring to fully dissolve to obtain a tetrachloropalladic acid solution, adding bismuth chloride powder to anhydrous methanol and stirring to fully dissolve, and dissolving sodium borohydride solution in deionized water and stirring to fully dissolve; wherein the concentration of the hydrochloric acid is 10mM, the molar ratio of palladium chloride powder, bismuth chloride powder, and sodium borohydride is 1:4:40, the concentration of the tetrachloropalladic acid solution is 0.01M, the concentration of the bismuth chloride solution is 0.05M, and the concentration of the sodium borohydride solution is 2M; Step 2, adding the tetrachloropalladic acid solution obtained in the reaction of step 1 to the bismuth chloride solution and placing it on a constant temperature magnetic stirrer, stirring and mixing at 40°C to 60°C and at a speed of 800r / min to 1200r / min, then adding the sodium borohydride solution and continuing to stir for 5 minutes, and keeping the resulting solution at 60°C for 6 hours, a black bismuth-palladium bimetallic gel is generated at the bottom of the solution, and the upper layer of the solution is poured off to leave the bismuth-palladium gel, which is washed 2 to 3 times with deionized water and ethanol; Step 3: Place the bismuth-palladium bimetallic gel material washed in step 2 into a freeze dryer for freeze drying for 48 hours to finally obtain a bismuth-palladium bimetallic aerogel material.

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