A molybdenum adsorbing quaternary ammonium hydrogel based on gamma irradiation method and a preparation method and application thereof

Abstract

This invention discloses a molybdenum-adsorbed quaternary ammonium hydrogel based on γ-irradiation. Using dimethylamine ethyl methacrylate (DMAEMA) and acetic acid (AA) as comonomers and N,N'-methylenebisacrylamide (MBA) as a crosslinking agent, a tertiary amine copolymer hydrogel is formed through γ-irradiation crosslinking. This hydrogel is then quaternized using a dimethyl sulfate acetonitrile solution to obtain the molybdenum-adsorbed quaternary ammonium hydrogel Q-DAM. The Q-DAM contains O-H, -C=O, C-O-C, and quaternary ammonium groups, exhibiting a three-dimensional porous network structure. The preparation method includes the following steps: 1. Preparation of the tertiary amine copolymer hydrogel T-DAM; 2. Preparation of the quaternary ammonium hydrogel Q-DAM, wherein the irradiation conditions are: at room temperature, using Co-60 as the irradiation source, and a total absorbed dose of 45 kGy. When used as a column adsorption material in a molybdenum-technetium generator, the adsorption capacity remains at 410-500 mg / g under irradiation conditions of 50-500 kGy.

Description

Technical Field

[0001] This invention relates to column adsorption materials in molybdenum technetium generators, specifically to a molybdenum-adsorbed quaternary ammonium hydrogel based on γ-irradiation, its preparation method, and its application. Background Technology

[0002] Technetium-99m ( 99m Tc is the most commonly used radionuclide in nuclear medicine. Currently 99m The preparation method of Tc is as follows: using molybdenum-99 ( 99 Mo was used as a raw material, and molybdenum technetium was extracted using a molybdenum technetium generator. 99m Tc. And 99 In the preparation methods of Mo, the traditional method involves using highly enriched uranium. 235 U-fission is obtained. This method yields... 99 Mo exhibits high specific activity, therefore, although the adsorption capacity of traditional commercial alumina is only 2-20 mg / g, it can still meet practical application requirements. However, traditional preparation methods pose risks of nuclear proliferation and reactor aging. Using a non-fission preparation method, namely the neutron activation method, can avoid the technical problems of traditional methods; however, the resulting... 99 Mo has a low specific activity, which means that traditional commercial alumina cannot meet the requirements of practical applications. Therefore, it is necessary to use a column adsorbent with high Mo ion absorption capacity.

[0003] Among conventional adsorbent materials, chitosan, a natural polymer, stands out due to its polysaccharide composition, which is rich in amino and hydroxyl groups as active groups. This results in high adsorption performance, low cost, and biodegradability. For example, existing literature 1 (Brion-Roby R, Gagnon J, Nosrati S, et al. Adsorption and desorption of molybdenum (VI) in contaminated water using a chitosansorbent[J]. Journal of Water Process Engineering, 2018, 23:13-19.) utilizes chitosan through thermal cross-linking to form an insoluble chitosan adsorbent, achieving an adsorption capacity of 123 mg / g for Mo(VI). However, when this technical solution is applied to a molybdenum technetium generator, there is a technical problem that it is not practical. The specific reason is that, according to reference 2 (Wei Tuantuan, Wang Huirui, Sun Yanxiaofan, et al. Research progress on the degradation of polysaccharides by gamma ray irradiation [J]. Journal of Food Safety and Quality Testing, 2023, 14(02): 1-8.), chitosan undergoes degradation under irradiation conditions, that is, it does not have radiation resistance stability.

[0004] Furthermore, hydrogel-based materials, due to their three-dimensional network structure, possess the characteristic of absorbing large amounts of water in solution without dissolving, thus making them suitable for wastewater adsorption treatment. For example, existing literature 3 (Zhen-Ning, Lou, Ye-Xia, et al. Selectivity recovery of molybdenum(VI) from rhenium(VII) by amine-modified persimmon waste[J]. Rare Metals, 2016.) uses persimmon residue as raw material, prepares cross-linked materials through concentrated sulfuric acid cross-linking modification, and obtains modified persimmon wastewater NH2-CPT gel by grafting amine functional groups, achieving a maximum adsorption capacity of 172 mg / g for Mo(VI). This technical solution is also based on biomass materials; therefore, like existing literature 1, it lacks radiation resistance stability, thus limiting its application to wastewater adsorption treatment under non-irradiation conditions and making it unsuitable as a column chromatography adsorbent for molybdenum-technetium generators. 99 Mo; Furthermore, because this technical solution employs grafted amine functional groups, it directly results in a low adsorption capacity and similarly fails to meet the requirements for low specific activity. 99 Adsorption requirements for Mo. Summary of the Invention

[0005] The purpose of this invention is to provide a molybdenum-adsorbed quaternary ammonium hydrogel based on γ-irradiation, its preparation method, and its application. The basic principle of this invention is as follows: 1. By using γ-irradiation crosslinking, a one-step method for constructing a hydrogel matrix with a three-dimensional network structure is achieved without chemical initiators, resulting in a significantly simplified preparation process; 2. Through subsequent quaternization modification, the tertiary amine groups in the hydrogel are converted into strongly cationic quaternary ammonium groups, thereby significantly improving the resistance to Mo(VI) anions and MoO4. 2- Adsorption capacity.

[0006] The main functions of each component in the technical solution are as follows: Dimethylamine ethyl methacrylate (DMAEMA), as the main functional monomer, possesses a tertiary amine group, providing a reaction site for subsequent quaternization modification, thus achieving the function of introducing a strongly adsorbed quaternary ammonium. Acrylic acid AA, as a comonomer, has a carboxyl group -COOH that can produce a synergistic effect with the electrostatic adsorption of quaternary ammonium groups, thus significantly improving adsorption performance. N,N'-methylenebisacrylamide (MBA) was used as a crosslinking agent and copolymerized with monomers under γ-irradiation to construct a three-dimensional crosslinked network structure of hydrogel, which improved the stability of the material skeleton. Dimethyl sulfate, acting as a quaternizing agent, reacts with the tertiary amine group on the DMAEMA chain segment to generate a positively charged quaternary ammonium group -N. + (CH3)3), achieving a significant improvement in the hydrogel's resistance to MoO4. 2- The role of anion adsorption.

[0007] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A molybdenum-adsorbed quaternary ammonium hydrogel based on gamma irradiation is obtained by crosslinking a tertiary amine copolymer hydrogel with dimethylamine ethyl methacrylate (DMAEMA) and acrylic acid (AA) as comonomers and N,N'-methylenebisacrylamide (MBA) as a crosslinking agent via gamma irradiation, followed by quaternization modification with dimethyl sulfate acetonitrile solution to obtain the molybdenum-adsorbed quaternary ammonium hydrogel Q-DAM. The Q-DAM contains OH, -C=O, COC, and quaternary ammonium groups and has a three-dimensional porous network structure.

[0008] A method for preparing molybdenum-adsorbed quaternary ammonium hydrogel based on γ-irradiation includes the following steps: Step 1, Preparation of tertiary amine copolymer hydrogel: First, dimethylamine ethyl methacrylate (DMAEMA) and acrylic acid (AA) are mixed to obtain mixture A. Then, N,N'-methylenebisacrylamide (MBA) and deionized water are added to mixture A to obtain mixed solution B. After that, mixed solution B is stirred to obtain a clear and transparent prepolymer solution C. Finally, prepolymer solution C is irradiated. After irradiation, it is rinsed with deionized water to obtain tertiary amine copolymer hydrogel T-DAM. In step 1, the stirring conditions for mixed solution B are: stirring time of 30-50 minutes; In step 1, the mass ratio of DMAEMA, AA and MBA is 70:30:6; In step 1, the irradiation conditions are as follows: at room temperature, Co-60 is used as the irradiation source, and the total absorbed dose is 45 kGy. Step 2, preparation of quaternary ammonium hydrogel: First, the T-DAM obtained in Step 1 is immersed in dimethyl sulfate acetonitrile solution and shaken at a constant temperature. Finally, it is freeze-dried under vacuum to obtain molybdenum adsorbed quaternary ammonium hydrogel Q-DAM based on γ-irradiation method. In step 2, the freeze-drying conditions are: freeze-drying temperature of -50℃ and freeze-drying time of 24-48h. In step 2, the isothermal oscillation conditions are as follows: oscillation temperature is 25℃, oscillation speed is 100 rpm, oscillation time is 5 h, and the concentration of dimethyl sulfate acetonitrile solution is 2.0 mol / mL.

[0009] When molybdenum-adsorbed quaternary ammonium hydrogels are used as column adsorption materials in molybdenum technetium generators, the adsorption capacity remains at 410-500 mg / g under irradiation conditions with an absorbed dose of 50-500 kGy.

[0010] The technical effects of this invention have been tested experimentally, and the specific results are as follows: FTIR and TG tests show that Q-DAM has characteristic peaks for OH, -C=O, and COC, and also has characteristic peaks for quaternary ammonium groups. Combined with the weight loss stage at 310-370℃, i.e. the breakage and removal of quaternary ammonium groups, it indicates that Q-DAM has been successfully quaternized.

[0011] SEM testing revealed that Q-DAM exhibits a cross-linked porous structure.

[0012] Radiation resistance stability tests show that QADMEMA-AA has an adsorption capacity of 410-500 mg / g under absorbed dose conditions of 50-500 kGy; and Q-DAM exhibits radiation resistance stability.

[0013] Therefore, the molybdenum-adsorbed quaternary ammonium hydrogel of the present invention has the following advantages: 1. The following advantages are obtained based on the gamma irradiation method: 1.1 The preparation method is simple. Compared with the traditional chemical cross-linking method, no additional chemical initiator is required, which can significantly reduce the preparation time and reduce the preparation cost. 1.2. Q-DAM hydrogels with stable three-dimensional network structures can be obtained, and they have radiation stability; 2. Based on the quaternization modification, the following advantages are obtained: Q-DAM, after quaternization modification, makes the gel positively charged and improves the adsorption capacity of the hydrogel for Mo(VI). Attached Figure Description

[0014] Figure 1 The FTIR images are of T-DAM and Q-DAM in Example 1; Figure 2 The TG plot of T-DAM in Example 1; Figure 3 The TG plot of Q-DAM in Example 1; Figure 4 This is a SEM image of the Q-DAM cross section in Example 1. Detailed Implementation

[0015] The present invention will be further described in detail through embodiments and with reference to the accompanying drawings, but this is not intended to limit the scope of the invention. Example

[0016] A method for preparing molybdenum-adsorbed quaternary ammonium hydrogel based on γ-irradiation includes the following steps: Step 1, Preparation of tertiary amine copolymer hydrogel: First, 1.6 g of DMAEMA and 0.4 g of AA were mixed in a mass ratio of 70:30:6 to obtain mixture A. Then, 0.12 g of MBA and 20 g of deionized water were added to mixture A to obtain mixed solution B. After stirring for 50 min, mixed solution B was stirred to obtain a clear and transparent prepolymer solution C. Finally, prepolymer solution C was irradiated at room temperature using Co-60 as the irradiation source with a total absorbed dose of 45 kGy. After irradiation, it was rinsed with deionized water to obtain the hydrogel. Since DMAEMA contains tertiary amine groups, the hydrogel obtained in Step 1 is a tertiary amine copolymer hydrogel, abbreviated as T-DAM. To confirm the composition of T-DAM, FTIR testing was performed. The test results are as follows: Figure 1 As shown, T-DAM exhibits characteristic peaks for OH, -C=O, and COC. The OH functional group originates from the carboxyl group in AA, the -C=O functional group originates from the ester group in DMAEMA and the carboxyl group in AA, and the COC functional group originates from the ester bond in the DMAEMA molecular structure. Meanwhile, no C=C double bond functional groups, present in both DMAEMA and AA, were detected. The test results indicate that, as monomers, DMAEMA and AA undergo free radical polymerization of their carbon-carbon double bonds under irradiation, forming a cross-linked hydrogel network with ester and carboxyl functional groups.

[0017] To further confirm the composition of T-DAM, TG testing was performed. The test results are as follows: Figure 2 As shown, T-DAM exhibits three weightlessness stages within a temperature range of 20-600℃. The first stage of weight loss is at 50-100℃, which is due to the removal of free water from the hydrogel. The second stage of weight loss occurs at 200-300℃, which is due to the decomposition of polymer side chains. The third stage of weight loss occurs at 360-420℃, which is caused by the breakage of the polymer backbone.

[0018] To compare the adsorption performance with that of Q-DAM, the T-DAM obtained in step 1 was tested for adsorption of Mo(VI) solution. The specific method for the adsorption test was as follows: the molybdenum solution concentration was 20 mg / L, the volume was 200 mL, and the mass of the adsorbent material, i.e., T-DAM, was 4.0 mg. The test results are shown in Table 1; the adsorption capacity of T-DAM was 268 mg / g.

[0019] Table 1 Comparison of adsorption capacities of T-DAM and Q-DAM

[0020] Step 2, preparation of quaternary ammonium hydrogel: First, the T-DAM obtained in Step 1 was immersed in a 2.0 mol / mL dimethyl sulfate acetonitrile solution and oscillated at a constant temperature under the conditions of oscillation temperature of 25℃, oscillation speed of 100 rpm, and oscillation time of 5 h. Finally, it was freeze-dried under vacuum under the conditions of freeze-drying temperature of -50℃ and freeze-drying time of 24 h to obtain a molybdenum adsorbed quaternary ammonium hydrogel based on γ-irradiation method, abbreviated as Q-DAM.

[0021] To verify the composition of Q-DAM, FTIR testing was performed. The test results are as follows: Figure 1 As shown, Q-DAM exhibits characteristic peaks for OH, -C=O, and COC, as well as characteristic peaks for quaternary ammonium groups. The test results indicate that Q-DAM was successfully prepared by quaternizing T-DAM through step 2.

[0022] To further confirm the composition of Q-DAM, TG testing was performed. The test results are as follows: Figure 3 As shown, in addition to the three weight loss stages of T-DAM, Q-DAM exhibits a new weight loss stage at 310-370℃. This is because the quaternary ammonium groups introduced after quaternization modification undergo breakage and removal within this temperature range. Test results also indicate that quaternization of T-DAM is achieved through step 2. To verify the microstructure of Q-DAM, SEM tests were performed on the cross-section. The test results are as follows: Figure 4 As shown, Q-DAM exhibits a cross-linked porous structure.

[0023] To demonstrate the adsorption performance of Q-DAM, Mo(VI) adsorption performance was tested. The test results are shown in Table 1. The adsorption capacity of Q-DAM was 491 mg / g. Compared with T-DAM obtained in step 1, quaternization can significantly improve the adsorption capacity for Mo(VI), with an increase of 83.2%.

[0024] To further demonstrate the radiation resistance of Q-DAM, specifically its application as a column adsorbent in molybdenum-technetium generators, radiation stability tests were conducted. The test results are shown in Table 2. Under absorbed dose conditions of 50-500 kGy, the adsorption capacity of QADMEMA-AA was 410-500 mg / g. These results indicate that Q-DAM possesses radiation resistance.

[0025] Table 2 Radiation resistance test results at different absorbed doses

[0026] To demonstrate the effect of the mass ratio of DMAEMA and AA as monomers on the adsorption properties of hydrogels, Comparative Example 1 and Comparative Example 2 are provided, with hydrogel materials prepared by mass ratios of DMAEMA and AA of 90:10 and 60:40, respectively.

[0027] Comparative Example 1 A method for preparing a hydrogel with a mass ratio of 90:10, wherein the steps not specifically described are the same as those in Example 1, except that in step 1, the mass ratio of DMAEMA and AA is replaced by 90:10 instead of 70:30, and the resulting hydrogel is referred to as Q-DAM-90:10.

[0028] The adsorption performance test results of Q-DAM-90:10 are shown in Table 1. The adsorption capacity of Q-DAM-90:10 is 154 mg / g. Compared with Q-DAM obtained in Example 1, it can be seen that due to the lower AA content, the synergistic adsorption effect of the carboxyl groups is reduced, resulting in a decrease in adsorption performance, which is only 31.3% of that of Q-DAM.

[0029] Comparative Example 2 A method for preparing a hydrogel with a mass ratio of 60:40 is provided. The steps unless otherwise specified are the same as those in Example 1, except that in step 1, the mass ratio of DMAEMA and AA is replaced by 60:40 instead of 70:30. The resulting hydrogel is referred to as Q-DAM-60:40.

[0030] The adsorption performance test results of Q-DAM-60:40 are shown in Table 1. The adsorption capacity of Q-DAM-60:40 is 266 mg / g. Compared with Q-DAM obtained in Example 1, it can be seen that because the adsorption effect of AA itself is not as good as that of quaternary ammonium groups, and the negative charge brought by AA shields part of the positive charge of quaternary ammonium (i.e., shielding effect), the adsorption sites become ineffective. Therefore, when the AA content is too high, the adsorption effect is reduced, only 54.1% of that of Q-DAM.

[0031] As can be seen from Examples 1, 1, and 2, when the AA content is low, the adsorption capacity decreases due to poor synergistic effect; when the AA content is high, the adsorption capacity decreases due to poor adsorption performance and the presence of a shielding effect.

[0032] To demonstrate the effect of total absorbed irradiation dose on the adsorption performance of hydrogels, comparative examples 3, 4, 5, and 6 were provided, with hydrogels prepared at total absorbed doses of 5 kGy, 15 kGy, 30 kGy, and 60 kGy, respectively.

[0033] Comparative Example 3 A method for preparing a hydrogel with a total absorbed dose of 5 kGy, wherein the steps not specifically described are the same as those in Example 1, except that in step 1, the absorbed dose is replaced by 5 kGy instead of 45 kGy, and the resulting hydrogel is referred to as Q-DAM-5 kGy.

[0034] The adsorption performance test results of Q-DAM-5 kGy are shown in Table 3. The adsorption capacity of Q-DAM-5 kGy is 387 mg / g.

[0035] Table 3 Adsorption capacity of materials at different total absorbed doses

[0036] Comparative Example 4 A method for preparing a hydrogel with a total absorbed dose of 15 kGy, wherein the steps not specifically described are the same as those in Example 1, except that in step 1, the absorbed dose is replaced by 15 kGy instead of 45 kGy, and the resulting hydrogel is referred to as Q-DAM-5 kGy.

[0037] The adsorption performance test results of Q-DAM-15 kGy are shown in Table 3. The adsorption capacity of Q-DAM-5 kGy is 417 mg / g.

[0038] Comparative Example 5 A method for preparing a hydrogel with a total absorbed dose of 30 kGy, wherein the steps not specifically described are the same as those in Example 1, except that in step 1, the absorbed dose is replaced by 30 kGy instead of 45 kGy, and the resulting hydrogel is referred to as Q-DAM-30 kGy.

[0039] The adsorption performance test results of Q-DAM-30 kGy are shown in Table 3. The adsorption capacity of Q-DAM-30 kGy is 441 mg / g.

[0040] Comparative Example 6 A method for preparing a hydrogel with a total absorbed dose of 60 kGy, wherein the steps not specifically described are the same as those in Example 1, except that in step 1, the absorbed dose is replaced by 60 kGy instead of 45 kGy, and the resulting hydrogel is referred to as Q-DAM-60 kGy.

[0041] The adsorption performance test results of Q-DAM-60 kGy are shown in Table 3. The adsorption capacity of Q-DAM-60 kGy is 471 mg / g.

[0042] As shown in Example 1 and Comparative Examples 3-6, the total absorbed irradiation dose has a significant impact on the adsorption performance of the hydrogel. Specifically, Under low absorbed dose conditions, the lack of free radicals generated by irradiation prevents the cross-linking reaction from being fully initiated, resulting in the inability to form a good three-dimensional network, fewer adsorption sites, and ultimately lower adsorption capacity. Under conditions of excessively high absorbed dose, excessive cross-linking occurs, which not only leads to the formation of a dense network in the hydrogel, but also causes degradation due to irradiation, ultimately resulting in a decrease in adsorption capacity.

Claims

1. A molybdenum-adsorbed quaternary ammonium hydrogel based on γ-irradiation, characterized in that: Using dimethylamine ethyl methacrylate (DMAEMA) and acrylic acid (AA) as comonomers and N,N'-methylenebisacrylamide (MBA) as a crosslinking agent, a tertiary amine copolymer hydrogel was formed by γ-irradiation crosslinking. Then, quaternization modification was achieved by dimethyl sulfate acetonitrile solution to obtain molybdenum-adsorbed quaternary ammonium hydrogel Q-DAM.

2. The molybdenum-adsorbed quaternary ammonium hydrogel according to claim 1, characterized in that: The Q-DAM contains OH, -C=O, COC and quaternary ammonium groups.

3. The molybdenum-adsorbed quaternary ammonium hydrogel according to claim 1, characterized in that: The Q-DAM has a three-dimensional porous network structure.

4. A method for preparing molybdenum-adsorbed quaternary ammonium hydrogel based on γ-irradiation, characterized in that... Includes the following steps: Step 1, Preparation of tertiary amine copolymer hydrogel: First, dimethylamine ethyl methacrylate (DMAEMA) and acrylic acid (AA) are mixed to obtain mixture A. Then, N,N'-methylenebisacrylamide (MBA) and deionized water are added to mixture A to obtain mixed solution B. After that, mixed solution B is stirred to obtain a clear and transparent prepolymer solution C. Finally, prepolymer solution C is irradiated. After irradiation, it is rinsed with deionized water to obtain tertiary amine copolymer hydrogel T-DAM. In step 1, the stirring conditions for mixed solution B are: stirring time of 30-50 min; Step 2, preparation of quaternary ammonium hydrogel: First, the T-DAM obtained in Step 1 is immersed in dimethyl sulfate acetonitrile solution and shaken at a constant temperature. Finally, it is freeze-dried under vacuum to obtain molybdenum adsorbed quaternary ammonium hydrogel Q-DAM based on γ-irradiation method. In step 2, the freeze-drying conditions are: freeze-drying temperature of -50℃ and freeze-drying time of 24-48 h.

5. The preparation method according to claim 4, characterized in that: In step 1, the mass ratio of DMAEMA, AA, and MBA is 70:30:

6.

6. The preparation method according to claim 4, characterized in that: In step 1, the irradiation conditions are as follows: at room temperature, Co-60 is used as the irradiation source, and the total absorbed dose is 45 kGy.

7. The preparation method according to claim 4, characterized in that: In step 2, the isothermal oscillation conditions are as follows: oscillation temperature is 25℃, oscillation speed is 100 rpm, oscillation time is 5 h, and the concentration of dimethyl sulfate acetonitrile solution is 2.0 mol / mL.

8. The molybdenum-adsorbed quaternary ammonium hydrogel according to claim 1, characterized in that: When used as a column adsorption material in molybdenum technetium generators, the adsorption capacity remains at 410-500 mg / g under irradiation conditions with an absorbed dose of 50-500 kGy.

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