A polybenzimidazole functionalized silicon-based resin, its preparation method and applications

Abstract

The application discloses a preparation method of a polybenzimidazole functionalized silicon-based resin, and comprises the following operation steps: S1, preparing polybenzimidazole; S2, preparing polybenzimidazole functionalized silicon-based resin; and S3, heat treating and optimizing the polybenzimidazole functionalized silicon-based resin. The application also provides the polybenzimidazole functionalized silicon-based resin prepared by the preparation method of the polybenzimidazole functionalized silicon-based resin and application of the polybenzimidazole functionalized silicon-based resin. The silicon-based resin provided by the application contains rich nitrogen sites, realizes high adsorption capacity of palladium ions under high acid conditions, and has excellent selective separation; and after elution, the silicon-based resin can be reused, thereby effectively solving the problems of low adsorption capacity of palladium, poor selectivity, poor acid and radiation resistance stability, and low reusability of existing adsorption materials under the condition of high-level liquid waste with extremely complex components and high radioactivity.

Description

Technical Field

[0001] This application relates to the field of adsorption and separation materials technology, and in particular to a polybenzimidazole functionalized silicon-based resin, its preparation method, and its application. Background Technology

[0002] Palladium is an important member of the platinum group metals (ruthenium, rhodium, palladium, osmium, iridium, and platinum). Its abundance in the Earth's crust is less than 0.52 ppb, with estimated global reserves of approximately 3220 tons. Due to its excellent chemical stability, corrosion resistance, thermal stability, catalytic activity, and high electrical and thermal conductivity, it is widely used in high-tech fields such as the automotive industry, petrochemical industry, electronics and information industry, and biomedicine, making it a crucial raw material for modern industry. With the rapid development of high-tech industries, the applications of palladium are becoming increasingly widespread, and the demand for it is also growing. However, my country's platinum group metal resources are severely scarce, with reserves of only 324 tons, accounting for only 0.2% of global reserves, resulting in a significant supply-demand imbalance. Therefore, developing a technology to separate and recover palladium from secondary resources is of great significance for the strategic supply of palladium resources.

[0003] Currently, there are over 430 nuclear power plants in operation worldwide, generating a large amount of spent fuel annually. According to incomplete statistics, there are approximately 120,000 tons of spent fuel worldwide, and this figure is rapidly increasing by 7,200 tons per year. The precious metal palladium is used as nuclear fuel. 235 U or 239 Pu is one of the main fission products, and its content is considerable. It is estimated that by 2030, 1000 tons of fission-generated Pd will accumulate in spent fuel, potentially becoming an alternative resource to meet growing demand. Furthermore, during the vitrification of high-level radioactive waste (HLLW), the presence of high-melting-point palladium increases the melting point of the glass and tends to form independent phases, leading to inhomogeneity in the glass matrix, affecting glass stability, increasing the difficulty of the vitrification process, and raising the risk of radioactive material leakage during long-term storage. Therefore, the effective separation and recovery of palladium fission products from HLLW can not only realize the recovery of strategic palladium resources and alleviate the supply and demand imbalance of palladium resources in my country, but also eliminate its negative impacts during spent fuel reprocessing, reduce the difficulty of HLLW treatment, and improve the stability and safety of HLLW vitrification.

[0004] The main existing methods for separating palladium, a fission product, include coprecipitation, solvent extraction, membrane separation, biological methods, electrodeposition, and adsorption. Compared with other separation methods, solid-liquid adsorption has advantages such as high adsorption efficiency, high selectivity, low cost, and reusability. Existing palladium adsorbents mainly include natural adsorbents such as zeolite and activated carbon, inorganic nanomaterials, framework materials, and other inorganic and organic adsorbents. However, these materials have disadvantages such as poor selectivity and low adsorption capacity. For example, the adsorption capacity of nano-Fe3O4 particles is low, only 10.6 mg / g; the adsorption capacity of UHMWPE-PMDA chelating resin for Pd(II) is significantly greater than that for other metal ions (the concentrations of coexisting ions such as Cu(II), Zn(II), Cr(II), Fe(III), and Ni(II) are much higher than the concentration of Pd(II), with a maximum adsorption capacity of about 221.8 mg / g. However, this adsorbent has poor adsorption capacity in high acidity. In existing literature, the maximum adsorption capacities of novel heterocyclic polymers PS-MBO, PS-MBI, and PS-MMBT for Pd(II) are 171.2 mg / g, 138.8 mg / g, and 142.0 mg / g, respectively. However, their adsorption efficiency and selectivity significantly deteriorate with increasing acidity. UIO-66 exhibits a maximum adsorption capacity of only 45 mg / g for palladium in a 1 mol / L nitric acid system, with poor selectivity. The extraction rates for Ag and Se are both above 70%. Therefore, developing an adsorbent material with high palladium adsorption capacity, good selectivity, strong acid resistance, and reusability under high acid conditions is of great significance. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a polybenzimidazole-functionalized silicon-based resin, its preparation method, and its application. This silicon-based resin contains abundant nitrogen sites, enabling high adsorption capacity and excellent selective separation of palladium ions under high acid conditions. Furthermore, it can be reused after elution, effectively solving the problems of low palladium adsorption capacity, poor selectivity, poor acid and radiation resistance, and low reusability of existing adsorbent materials under conditions of highly radioactive waste liquid with extremely complex composition and high radioactivity.

[0006] The technical solution provided by this invention is as follows:

[0007] A method for preparing a polybenzimidazole-functionalized silicone resin includes the following steps:

[0008] S1. Preparation of polybenzimidazole: Under a protective atmosphere, polyphosphoric acid is mixed with 3,3',4,4'-tetraaminobiphenyl and malonic acid and reacted at a certain temperature to obtain a solid product. The solid product is filtered and washed to obtain a solid powder. The fixed powder is purified to obtain polybenzimidazole.

[0009] S2. Preparation of polybenzimidazole functionalized silicone resin: Polybenzimidazole is dissolved in an organic solvent to prepare a polybenzimidazole solution. Under vacuum, the polybenzimidazole solution is immersed into the silica pores until the solvent is completely evaporated. After the vacuum impregnation is completed, polybenzimidazole functionalized silicone resin is obtained.

[0010] S3. Heat treatment optimization of polybenzimidazole functionalized silicone resin: The polybenzimidazole functionalized silicone resin is heat-treated at 120℃~300℃ for a period of time to obtain the optimized polybenzimidazole functionalized silicone resin.

[0011] Preferably, in step S1, the amounts of polyphosphoric acid, 3,3',4,4'-tetraaminobiphenyl, and malonic acid added are, by mass fraction, 90-95 parts of polyphosphoric acid, 3-5 parts of 3,3',4,4'-tetraaminobiphenyl, and 2-4 parts of 3,3',4,4'-tetraaminobiphenyl.

[0012] Preferably, the specific process of mixing polyphosphoric acid with 3,3',4,4'-tetraaminobiphenyl and malonic acid in step S1 is as follows: Connect a nitrogen-purging tube and an electric stirrer to a dried three-necked flask, add polyphosphoric acid to the three-necked flask, place it in an oil bath, introduce N2, and under nitrogen protection, turn on the stirrer, slowly raise the temperature to 60-85°C and stir to remove oxygen for 0.5-1.5 hours, then lower the temperature to 20-35°C and add 3,3',4,4'-tetraaminobiphenyl, and stir and purge with nitrogen at room temperature for 20-45 minutes, then raise the temperature to 60-85°C and continue stirring to remove oxygen, heating until 3,3',4,4'-tetraaminobiphenyl is completely dissolved in the solvent, cool to room temperature, add malonic acid, and then purge with nitrogen at room temperature to remove oxygen.

[0013] Preferably, the reaction process in step S1 is as follows: heating under oil bath conditions, so that the system reacts at 110-130°C for 3-5 hours, at 150-160°C for 7-9 hours, and at 200-220°C for 11-13 hours.

[0014] Preferably, the impurity removal process of the solid powder in step S1 is as follows: the solid powder is soaked in an aqueous solution of 10-15% NaHCO3 for 2-3 days to neutralize the residual acid in the polymer, and finally the polymer is washed with deionized water until neutral. The obtained polymer is then dried in a vacuum drying oven for 24-48 hours.

[0015] Preferably, in step S2, the amount of polybenzimidazole and silica added is, by mass fraction, 30-35 parts of polybenzimidazole and 65-70 parts of silica.

[0016] Preferably, the specific process of immersing the polybenzimidazole solution into the silica pores in step S2 is as follows: First, weigh a certain amount of porous SiO2 microsphere carrier into a flask, then weigh a certain amount of the polybenzimidazole prepared in step S1 and dissolve it in an appropriate amount of organic solvent. Heat appropriately to accelerate dissolution. After complete dissolution, transfer it into the flask. Finally, fix the flask to a rotary evaporator and use a vacuum pump to evacuate the flask to a pressure of 20-50 hPa. Then, fill it with inert gas to restore it to atmospheric pressure. Repeat the above steps 2-3 times to displace the air in the flask. Maintain the flask rotation speed at 60-80 rpm at room temperature and pressure for 1-2 hours. Then, let it stand for 2-4 hours. Heat it in an oil bath to 110-130°C and maintain the flask rotation speed at 60-80 rpm for 1.5-2 hours. While heating, turn on the cooling water circulation device. After the above steps are completed, turn on the vacuum pump and slowly reduce the pressure to immerse the polybenzimidazole into the silica pores.

[0017] Preferably, the organic solvent in step S2 is N-methylpyrrolidone or dimethyl sulfoxide.

[0018] A polybenzimidazole-functionalized silicone resin is prepared using the above-described method for preparing polybenzimidazole-functionalized silicone resin.

[0019] An adsorbent material for separating palladium from high-level radioactive waste liquid includes the polybenzimidazole-functionalized silicon-based resin described above or the polybenzimidazole-functionalized silicon-based resin prepared by the above preparation method.

[0020] This application has the following advantages over the prior art:

[0021] The polybenzimidazole-functionalized silicon-based resin provided by this invention is a high-performance material with good acid resistance and radiation resistance. It contains abundant imidazole nitrogen (C═N─C), which belongs to the soft base group. According to the soft-hard acid-base theory, imidazole nitrogen readily combines with soft acid metal ions (Pd(II)) to form coordination compounds, exhibiting high selectivity for Pd(II). The adsorption capacity of the heat-treated optimized polybenzimidazole-functionalized silicon-based resin for palladium increases with increasing acidity, achieving high adsorption capacity for palladium in high-acid concentration solutions (1–9 mol / L HNO3). - It participates in coordination equilibrium and achieves specific selective separation of palladium in high-nitric acid concentration solutions. The resin of this invention effectively solves the problems of low adsorption capacity, poor selectivity, poor acid and radiation resistance, and low reusability of existing adsorbent materials in highly complex, radioactive, and corrosive high-level radioactive waste liquids, achieving selective separation of Pd(II) under high acid conditions. Attached Figure Description

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

[0023] Figure 1 This is a synthetic route diagram of the preparation method of polybenzimidazole functionalized silicone resin in the embodiments of the present invention;

[0024] Figure 2 This is the FT-IR image of the polybenzimidazole-functionalized silicone resin in the embodiments of the present invention;

[0025] Figure 3 This is a thermogravimetric analysis diagram of the polybenzimidazole-functionalized silicone resin in an embodiment of the present invention;

[0026] Figure 4 The effect of initial nitric acid concentration on palladium adsorption of polybenzimidazole-functionalized silicon-based resin at different calcination temperatures;

[0027] Figure 5 The effect of different initial concentrations of nitric acid on the selective adsorption of palladium. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] like Figure 1 As shown, this embodiment of the invention provides a method for preparing polybenzimidazole functionalized silicone resin, comprising the following steps:

[0030] S1. Preparation of polybenzimidazole: Under a protective atmosphere, polyphosphoric acid is mixed with 3,3',4,4'-tetraaminobiphenyl and malonic acid and reacted at a certain temperature to obtain a solid product. The solid product is filtered and washed to obtain a solid powder. The fixed powder is purified to obtain polybenzimidazole.

[0031] S2. Preparation of polybenzimidazole functionalized silicone resin: Polybenzimidazole is dissolved in an organic solvent to prepare a polybenzimidazole solution. Under vacuum, the polybenzimidazole solution is immersed into the silica pores until the solvent is completely evaporated. After the vacuum impregnation is completed, polybenzimidazole functionalized silicone resin is obtained.

[0032] S3. Heat treatment optimization of polybenzimidazole functionalized silicone resin: The polybenzimidazole functionalized silicone resin is heat-treated at 120℃~300℃ for a period of time to obtain the optimized polybenzimidazole functionalized silicone resin.

[0033] In this embodiment, the amounts of polyphosphoric acid, 3,3',4,4'-tetraaminobiphenyl, and malonic acid added in step S1 are as follows by mass fraction: 90-95 parts of polyphosphoric acid, 3-5 parts of 3,3',4,4'-tetraaminobiphenyl, and 2-4 parts of 3,3',4,4'-tetraaminobiphenyl.

[0034] In this embodiment, the specific process of mixing polyphosphoric acid with 3,3',4,4'-tetraaminobiphenyl and malonic acid in step S1 is as follows: Connect a nitrogen-purging tube and an electric stirrer to a dried three-necked flask, add polyphosphoric acid to the three-necked flask, place it in an oil bath, introduce N2, and under the protection of nitrogen, turn on the stirrer, slowly raise the temperature to 60-85°C and stir to remove oxygen for 0.5-1.5 hours, then lower the temperature to 20-35°C and add 3,3',4,4'-tetraaminobiphenyl, and stir and purge with nitrogen at room temperature for 20-45 minutes, then raise the temperature to 60-85°C and continue stirring to remove oxygen. Continue heating until 3,3',4,4'-tetraaminobiphenyl is completely dissolved in the solvent, cool to room temperature, add malonic acid, and then purge with nitrogen at room temperature to remove oxygen.

[0035] In this embodiment, the reaction process in step S1 is specifically as follows: heating under oil bath conditions, so that the system reacts at 110-130°C for 3-5 hours, at 150-160°C for 7-9 hours, and at 200-220°C for 11-13 hours.

[0036] In this embodiment, the impurity removal process of the solid powder in step S1 is as follows: the solid powder is soaked in an aqueous solution of 10-15% NaHCO3 for 2-3 days to neutralize the residual acid in the polymer, and finally the polymer is washed with deionized water until neutral. The obtained polymer is then dried in a vacuum drying oven for 24-48 hours.

[0037] In this embodiment, the amount of polybenzimidazole and silica added in step S2 is as follows by mass fraction: 30-35 parts of polybenzimidazole and 65-70 parts of silica.

[0038] In this embodiment, the specific process of immersing the polybenzimidazole solution into the silica pores in step S2 is as follows: First, a certain amount of porous SiO2 microspheres are weighed into a flask. Then, a certain amount of the polybenzimidazole prepared in step S1 is weighed and dissolved in an appropriate amount of organic solvent. The solution is heated appropriately to accelerate dissolution. After complete dissolution, the solution is transferred into the flask. Finally, the flask is fixed to a rotary evaporator, and a vacuum pump is used to evacuate the flask to a pressure of 20-50 hPa. Then, an inert gas is introduced to restore the pressure to atmospheric pressure. The above steps are repeated 2-3 times to displace the air in the flask. The flask is rotated at 60-80 rpm for 1-2 hours at room temperature and pressure. After standing for 2-4 hours, the flask is heated in an oil bath to 110-130°C. The flask is rotated at 60-80 rpm for 1.5-2 hours. The cooling water circulation device is turned on while heating. After the above steps are completed, the vacuum pump is turned on, and the polybenzimidazole is immersed into the silica pores by slowly reducing the pressure.

[0039] In this embodiment, the organic solvent in step S2 is N-methylpyrrolidone or dimethyl sulfoxide.

[0040] A polybenzimidazole-functionalized silicone resin is prepared by the above-mentioned method for preparing polybenzimidazole-functionalized silicone resin.

[0041] An adsorbent material for separating palladium from high-level radioactive waste liquid includes the above-mentioned polybenzimidazole functionalized silicon-based resin or the polybenzimidazole functionalized silicon-based resin prepared by the above-mentioned preparation method.

[0042] Example 1:

[0043] A method for preparing a polybenzimidazole-functionalized silicone resin specifically includes the following steps:

[0044] S1. Preparation of polybenzimidazole (PBI)

[0045] First, connect a nitrogen-purging tube and an electric stirrer to a dried 100mL three-necked flask. Add approximately 45g of polyphosphoric acid (PPA) to the flask, place it in an oil bath, and purge with N2. Under nitrogen protection, turn on the stirrer and slowly heat to 80℃ while stirring to remove oxygen for 1 hour. Then cool to near room temperature and add 2.02g (9.43mmol) of 3,3',4,4'-tetraaminobiphenyl. Stir and purge with nitrogen for 30 minutes at room temperature. Then heat to 80℃ and continue stirring to remove oxygen. Continue heating until the 3,3',4,4'-tetraaminobiphenyl is completely dissolved in the solvent. Cool again to room temperature, add 0.98g (9.42mmol) of malonic acid, and purge with nitrogen for 30 minutes at room temperature. Subsequently, heat in an oil bath at 120℃, 160℃, and 210℃ for 4 hours, 8 hours, and 12 hours, respectively. After the reaction was complete, when the solution in the three-necked flask cooled to room temperature, 70 mL of cold water was added to the three-necked flask and stirred rapidly for 1 hour. The mixture was filtered and the solid powder was repeatedly washed with deionized water. It was then soaked in a 10% NaHCO3 aqueous solution for 2 days to neutralize the residual acid in the polymer. Finally, the polymer was washed with deionized water until neutral. The obtained polymer was dried in a vacuum drying oven for 24 hours and ground in a mortar to obtain 1.93 g of yellowish-brown polybenzimidazole (PBI) powder, with a yield of 64.33%.

[0046] S2. Preparation of PBI-SiO2 resin

[0047] First, weigh 3g of white porous SiO2 microspheres into a flask. Then, weigh 1.6g of PBI prepared in step S1 and dissolve it in an appropriate amount of N-methylpyrrolidone (NMP). Heat appropriately to accelerate dissolution. After complete dissolution, transfer the solution into the flask. Finally, fix the flask to a rotary evaporator and use a vacuum pump to evacuate the flask to a pressure of 30 hPa. Then, fill with an inert gas (nitrogen or argon) to restore the pressure to atmospheric pressure. Repeat the above steps 2-3 times to displace the air in the flask. Maintain the flask rotation speed at 60 rpm for 1 hour at room temperature and pressure, and then let it stand for 2 hours. Heat the flask in an oil bath to 110℃, maintain the flask rotation speed at 60 rpm for 1.5 hours, and turn on the cooling water circulation device while heating. After the above steps are completed, turn on the vacuum pump and slowly immerse the PBI into the pores of the SiO2 using a depressurization method until the solvent completely evaporates. After vacuum impregnation, approximately 4.55g of yellowish-brown PBI-SiO2 resin is obtained.

[0048] S3. Heat treatment optimizes the properties of PBI-SiO2 resin (polybenzimidazole functionalized silicone resin).

[0049] Weigh 7 portions (0.5g each) of PBI-SiO2 prepared in step S2 into a crucible, place it in a drying oven, and heat-treat it at 120℃~300℃ for 0.5~1.5h to obtain PBI-SiO2 resins optimized for different temperatures.

[0050] Structural and property analysis was performed on the PBI-SiO2 resin synthesized in Example 1:

[0051] Fourier transform infrared (FT-IR) spectroscopy analysis: Figure 2 The image shows the FT-IR spectra of the PBI-SiO2 resin, PBI, and SiO2 synthesized in this invention, at 1629 cm⁻¹. -1 The absorption peaks at 3365 and 3179 cm⁻¹ are due to the stretching vibration of the C=N bond. -1 The broad peaks at 1585, 1530, and 1451 cm⁻¹ are the free stretching vibration peak of NH₃ and the bound stretching vibration peak of NH₃, respectively. These peaks prove that the polymer contains an imidazole ring structure. -1 The peaks at the positions are the conjugation vibration peaks of the benzene ring and the imidazole ring, the in-plane ring vibration peaks of 2-substituted benzimazole, and the in-plane ring vibration peaks of 2,6-disubstituted benzimazole, respectively, which proves that PBI was successfully prepared. By comparing the FT-IR spectra of PBI-SiO2 resin, PBI and SiO2, it can be seen that PBI was successfully loaded on SiO2, indicating the successful synthesis of PBI-SiO2 resin.

[0052] Thermal stability analysis: Figure 3 The thermogravimetric analysis (TGA) diagrams of the PBI-SiO2 resins synthesized in this invention under different heat treatment temperatures are shown. The diagrams show that the PBI-SiO2 resins treated at temperatures of 140°C and below begin to decompose at 200°C; the PBI-SiO2 resins treated at temperatures of 160°C and above maintain more than 95% of their mass before reaching 400°C. As the temperature increases, the polymer structure begins to decompose, resulting in rapid and significant weight loss; at 700°C, the decomposition is essentially complete, and the organic content in the PBI-SiO2 resin is around 35%, consistent with theoretical expectations.

[0053] The palladium ion adsorption capacity of the PBI-SiO2 resin prepared in Example 1 above in acidic solution was tested:

[0054] To investigate the effect of different acidities on the adsorption performance of PBI-SiO2 resin after heat treatment optimization, 0.02 g of PBI-SiO2 resin adsorbent treated at different temperatures was weighed into nine glass bottles using an electronic balance. Solutions containing 2 mmol / L Pd(II) with HNO3 concentrations ranging from 0.01 to 9 M (0.01, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 9 M) were prepared. 5 mL of each of these HNO3-containing solutions was added to each of the nine glass bottles. The bottles were then covered with plastic caps and sealed with sealing film to prevent water from entering the bottles or leakage of the solution. Finally, the bottles were placed in a water bath at 25°C and a shaking frequency of 160 rpm for 24 hours to ensure adsorption equilibrium was reached. After shaking, the adsorbent was separated from the solution using a 0.22 μm pore size aqueous filter. The concentration of Pd(II) in the solution before and after adsorption was then measured using an ICP-NEO analyzer to calculate the adsorption rate (%) or adsorption capacity (mg / g). The experimental results are as follows: Figure 4 As shown, PBI-SiO2 resins heat-treated at different temperatures all exhibit adsorption effects on Pd(II). It can be observed that the adsorption rate of Pd(II) by PBI-SiO2 resins heat-treated below 200℃ first increases with increasing HNO3 concentration, reaching a maximum at 0.1 mol / L, then decreases, reaching a minimum at around 1 mol / L, and then increases again. However, the adsorption rate of Pd(II) by PBI-SiO2 resins heat-treated above 200℃ increases with increasing HNO3 concentration, reaching over 95% in the range of 1-6 mol / L. This indicates that PBI-SiO2 resins have a good adsorption effect on Pd(II) under high acid conditions, and the optimization of the heat treatment process greatly improves the acid resistance of PBI-SiO2 resins.

[0055] In high-level radioactive waste liquid, noble metal elements Pd, Rh, and Ru with similar chemical properties coexist, along with a large number of other ions. To investigate this, a selective adsorption experiment was conducted using PBI-SiO2 resin heat-treated at 220℃ in simulated high-level radioactive waste liquid. Experimental conditions: The concentrations of 15 metal ions (Pd, Rh, Ru, Sr, Cs, Mo, Zr, Gd, Eu, Sm, Nd, Pr, Ce, La, and Y) in the simulated high-level radioactive waste liquid were all 2 mmol / L; the concentrations of HNO3 in the solution were 0.01, 0.1, 0.5, 1, 2, 3, 4, 5, 6, and 9 mol / L, respectively; the solid-liquid ratio of PBI-SiO2 resin to the simulated high-level radioactive waste liquid was 0.02 g / 5 mL; the water bath temperature was 25℃; the shaking frequency was 160 rpm; and the adsorption time was 24 h. The experimental results are as follows: Figure 5As shown, PBI-SiO2 resin exhibited excellent adsorption capacity for Pd(II) in solutions containing 15 metal ions, with a separation factor SF₀ at acidity levels of 1-6 M HNO₃. Pd / other metal ions The value of ≥256.3 indicates that the PBI-SiO2 resin has excellent selectivity for the adsorption of Pd(Ⅱ).

[0056] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a polybenzimidazole-functionalized silicone resin, characterized in that, The following steps are included: S1. Preparation of polybenzimidazole: Under a protective atmosphere, polyphosphoric acid is mixed with 3,3',4,4'-tetraaminobiphenyl and malonic acid and reacted at a certain temperature to obtain a solid product. The solid product is filtered and washed to obtain a solid powder. The solid powder is purified to obtain polybenzimidazole. S2. Preparation of polybenzimidazole functionalized silicone resin: Polybenzimidazole is dissolved in an organic solvent to prepare a polybenzimidazole solution. Under vacuum, the polybenzimidazole solution is immersed into the silica pores until the solvent is completely evaporated. After the vacuum impregnation is completed, polybenzimidazole functionalized silicone resin is obtained. S3. Heat treatment optimization of polybenzimidazole functionalized silicone resin: The polybenzimidazole functionalized silicone resin is heat-treated at 120℃~300℃ for a period of time to obtain the optimized polybenzimidazole functionalized silicone resin.

2. The method for preparing polybenzimidazole functionalized silicone resin according to claim 1, characterized in that, In step S1, the amounts of polyphosphoric acid, 3,3',4,4'-tetraaminobiphenyl, and malonic acid added are as follows by mass fraction: 90-95 parts of polyphosphoric acid, 3-5 parts of 3,3',4,4'-tetraaminobiphenyl, and 2-4 parts of 3,3',4,4'-tetraaminobiphenyl.

3. The method for preparing polybenzimidazole functionalized silicone resin according to claim 1, characterized in that, The specific process of mixing polyphosphoric acid with 3,3',4,4'-tetraaminobiphenyl and malonic acid in step S1 is as follows: Connect a nitrogen-purging tube and an electric stirrer to a dried three-necked flask, add polyphosphoric acid to the flask, place it in an oil bath, purge with N2, and under nitrogen protection, turn on the stirrer, slowly raise the temperature to 60-85°C and stir to remove oxygen for 0.5-1.5 hours, then lower the temperature to 20-35°C and add 3,3',4,4'-tetraaminobiphenyl, and stir and purge with nitrogen at room temperature for 20-45 minutes, then raise the temperature to 60-85°C and continue stirring to remove oxygen. Continue heating until 3,3',4,4'-tetraaminobiphenyl is completely dissolved in the solvent, cool to room temperature, add malonic acid, and then purge with nitrogen at room temperature to remove oxygen.

4. The method for preparing polybenzimidazole functionalized silicone resin according to claim 3, characterized in that, The reaction process in step S1 is specifically as follows: heating under oil bath conditions, so that the system reacts at 110-130℃ for 3-5 hours, at 150-160℃ for 7-9 hours, and at 200-220℃ for 11-13 hours.

5. The method for preparing polybenzimidazole functionalized silicone resin according to claim 1, characterized in that, The impurity removal process of the solid powder in step S1 is as follows: the solid powder is soaked in a 10-15% NaHCO3 aqueous solution for 2-3 days to neutralize the residual acid in the polymer, and finally the polymer is washed with deionized water until neutral. The obtained polymer is then dried in a vacuum drying oven for 24-48 hours.

6. The method for preparing the polybenzimidazole functionalized silicone resin according to any one of claims 1-5, characterized in that, In step S2, the amount of polybenzimidazole and silica added is as follows by mass fraction: 30-35 parts of polybenzimidazole and 65-70 parts of silica.

7. The method for preparing the polybenzimidazole functionalized silicone resin according to any one of claims 1-5, characterized in that, The specific process of immersing the polybenzimidazole solution into the silica pores in step S2 is as follows: First, weigh a certain amount of porous SiO2 microsphere carrier into a flask. Then, weigh a certain amount of the polybenzimidazole prepared in step S1 and dissolve it in an appropriate amount of organic solvent. Heat appropriately to accelerate dissolution. After complete dissolution, transfer it into the flask. Finally, fix the flask to a rotary evaporator and use a vacuum pump to evacuate the flask to a pressure of 20-50 hPa. Then, fill it with inert gas to restore it to atmospheric pressure. Repeat the above steps 2-3 times to displace the air in the flask. Maintain the flask rotation speed at 60-80 rpm at room temperature and pressure for 1-2 hours. Then, let it stand for 2-4 hours. Heat it in an oil bath to 110-130°C and maintain the flask rotation speed at 60-80 rpm for 1.5-2 hours. While heating, turn on the cooling water circulation device. After the above steps are completed, turn on the vacuum pump and slowly reduce the pressure to immerse the polybenzimidazole into the silica pores.

8. The method for preparing the polybenzimidazole functionalized silicone resin according to any one of claims 1-5, characterized in that, The organic solvent in step S2 is N-methylpyrrolidone or dimethyl sulfoxide.

9. A polybenzimidazole-functionalized silicone resin, characterized in that, It is prepared by the method for preparing polybenzimidazole functionalized silicone resin according to any one of claims 1-8.

10. An adsorbent material for separating palladium from high-level radioactive waste liquid, characterized in that, This includes polybenzimidazole-functionalized silicone resins prepared by the preparation method according to any one of claims 1-8.

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