CN113214480B - Synthesis method and adsorption application of a cationic framework material - Google Patents

Abstract

The invention discloses a synthetic method and adsorption application of a cationic framework material, and belongs to the technical field of environmental protection. Firstly, a tripodia flexible ligand tri (4- (1H-imidazole-1-yl) phenyl) amine containing abundant imidazole groups is taken as a monomer to perform quaternization reaction with 1, 4-bis (bromomethyl) benzene to generate a cationic framework material (ImCOP) with positive charge imidazole groups. High density of positively charged imidazole groups with anionic ReO in ImCOP framework₄ ^‑Through the combination of electrostatic action, the ReO pair is greatly improved₄ ^‑The adsorption capacity of (c). The ImCOP skeleton is constructed by hydrophobic benzene ring and imidazole ring, so that the ImCOP is small in charge density to ReO₄ ^‑Has stronger affinity and selectivity than common competitive anions. The ImCOP prepared by the method has high stability in strong acid and strong alkali and is resistant to ReO₄ ^‑The method has the advantages of large adsorption capacity, fast kinetics, high selectivity and good application potential.

Description

Synthesis method and adsorption application of a cationic framework material

technical field

The invention belongs to the technical field of environmental protection, and in particular relates to a synthesis method and adsorption application of a cationic frame material.

Background technique

In order to meet the growing demand for energy and environmental protection, nuclear power is a very important option. With the booming nuclear power industry, nuclear power provides about 11% of the world's electricity. However, the safe disposal of the large quantities of radioactive nuclear waste generated in the nuclear industry is a very difficult issue. Radioactive nuclear waste is usually divided into cationic and anionic types, among which cationic radionuclides include ¹³⁷ Cs, ⁹⁰ Sr, ²³⁵ U, etc., and anionic radionuclides include ⁹⁹ Tc, ⁷⁹ Se, ¹²⁹ I, etc. At present, there are more studies on cationic radionuclides, but few studies on anionic radionuclides, especially on ⁹⁹ Tc. Since the first nuclear reactors, it is estimated that a typical U or Pu fission reactor has produced about 400 metric tons of ⁹⁹ Tc over the past 70 years (Xiao, C.; Khayambashi, A.; Wang, S. Separation and remediation of ⁹⁹ TcO ₄ ^– from aqueous solutions, Chemistry of Materials, 2019, 31:3863-3877), still untreated. In addition, in the past few decades, due to nuclear accidents and improper waste management, a large amount of radioactive waste has been released into the environment, which seriously threatens the ecological environment and human health. Therefore, radioactive waste treatment and pollution remediation urgently need to be solved.

The general strategy of nuclear waste treatment is to first separate solid waste and liquid waste by gravity, and then the nuclear waste is divided into two parts, high-level radioactive waste and low-level radioactive waste, and stored at the Hanford base in the United States. Smaller volumes of high-level radioactive waste are usually fixed in the form of borosilicate glass waste (a process called vitrification) but during the high temperature curing process of ⁹⁹ Tc, pertechnetate (TcO ₄ ^- ) is easily converted into volatile radioactive The gas Tc ₂ O ₇ is precipitated, so the method of vitrification is not suitable for removing ⁹⁹ Tc. The methods that have the potential to capture and remove TcO ₄ ^- are mainly ion exchange, extraction and precipitation (Katayev, EA; Kolesnikov, GV; Sessler, JLMolecular recognition of pertechnetate and perrhenate, Chemical Society Reviews, 2009, 31: 1572-1586) , among which the ion exchange method is simple and efficient, so it has attracted much attention in the removal of ⁹⁹ TcO ₄ ^- . Different types of inorganic materials (eg, nano-zero-valent iron, layered bimetallic hydroxides, porous carbon materials, etc.) have been studied most early on (Li, J.; Zhu, L.; Xiao, C.; Chen, L. .; Chai, Z.; Wang, S. Efficient uptake of perrhenate/pertechnenate from aqueous solutions by the bifunctional anion-exchange resin, Radiochimica Acta, 2018, 106:581-591). Ion exchange resin materials were used to deal with TcO ₄ ^- pollution in the Hanford area of the United States in the mid-1960s. Bonnesen et al. introduced long-chain alkyl quaternary ammonium salts into strong base anion resins to improve the affinity for TcO ₄ ^- . , even at low concentrations of TcO ₄ ^- has a good removal ability (Bonnesen, PV; Brown, GM; Alexandratos, SD; Bavoux, LB; Presley, DJ; Patel, V.; Ober, R.; Moyer, BA Development of Bifunctional Anion-Exchange Resins with Improved Selectivity and Sorptive Kinetics for Pertechnetate: Batch-Equilibrium Experiments, Environmental Science & Technology, 2000, 34: 3761-3766). However, ion exchange resins have relatively long synthesis cycles, complex synthesis processes, and are less stable under extreme conditions (eg, oxidation, irradiation, mechanical pressure, etc.), and the adsorption kinetics are slow during the exchange process, which usually requires For several hours or even days, in addition, inorganic exchange materials usually have poor adsorption properties, are unstable and easily soluble under extremely acidic conditions, and are negatively charged on the surface under alkaline conditions, which are not conducive to exchange with TcO ₄ ^-anions . Therefore, there is an urgent need to develop new materials that are stable under extreme conditions, have high adsorption capacity, good selectivity, and fast adsorption kinetics.

In recent years, polymeric networks built from repeating organic building blocks have been extensively studied and exhibit superior hydrolytic stability even in highly acidic/alkaline solutions, a distinct advantage that inorganic materials do not have. What's more, these structural features are predictable and highly tunable, allowing materials to be engineered for specific tasks. Polymers are characterized by good stability under different types of extreme conditions (e.g., high acidity, alkalinity, and salinity, etc.) due to the enhanced robustness of covalent-based linkages that build the structure; many polymers are It is highly conjugated and can stabilize the radical-based intermediates generated by radiation, which is also an advantage that traditional polymer anion exchange resins do not have. Therefore, the present invention designs and synthesizes imidazolyl cationic framework material (ImCOP), which contains abundant positively charged imidazole groups, which can be combined with perrhenate (ReO ₄ ^- ) or pertechnetate ( ⁹⁹ TcO ₄ ^- ) The anion interacts electrostatically, and the -NH- of the imidazolyl group in the framework forms a high-density hydrogen bond network with ReO ₄ ^- (ReO ₄ ^- has no radioactivity, and is often used to replace the radioactive ⁹⁹ TcO ₄ ^- for research), which improves the resistance to ReO ₄ ^- Moreover, the semi-rigid structure of the imidazolyl cationic framework material also improves its chemical stability. So far, there is no report on the adsorption and removal of ReO ₄ ^- / ⁹⁹ TcO ₄ ^- by imidazolyl cationic framework materials under strong acid/base conditions.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a synthesis method and adsorption application of a stable imidazolyl cationic framework material, which has the characteristics of simple operation, environmental friendliness, economic efficiency, and simultaneously ^imidazolyl cationic _framework ^- /ReO ₄ ^- has the advantages of high adsorption capacity, fast adsorption kinetics, high selectivity and high stability.

The present invention is achieved through the following technical solutions:

Using tris(4-(1H-imidazol-1-yl)phenyl)amine, a tripod flexible ligand rich in imidazolyl groups, as a monomer, quaternized with 1,4-bis(bromomethyl)benzene to generate Cationic framework materials with positively charged imidazole groups, the steps are as follows:

1) Using tris(4-(1H-imidazol-1-yl)phenyl)amine and 1,4-bis(bromomethyl)benzene as reaction raw materials, N,N-dimethylformamide and acetonitrile were added thereto After mixing uniformly, a reaction mixture is obtained;

2) the reaction mixture is stirred and refluxed under nitrogen atmosphere, and the nitrogen source is removed after cooling to room temperature to obtain a reaction product solution;

3) After suction filtration of the obtained reaction product solution, the precipitate is washed with N,N-dimethylformamide and absolute ethanol, and the imidazolyl cationic framework material ImCOP is obtained after the precipitate is dried.

Further, in step 1) the molar ratio of the tris(4-(1H-imidazol-1-yl)phenyl)amine to the 1,4-bis(bromomethyl)benzene is 1:(1-3) .

The present invention also provides an application of a cationic frame material in removing perrhenate/pertechnetate, comprising: adding the cationic frame material to a solution to be treated containing perrhenate, and shaking at room temperature.

Further, the concentration range of the solution to be treated containing perrhenate is 50-2000 mg/L.

Further, before shaking at room temperature, a pH regulator needs to be used to adjust the pH to 1-13; preferably, the pH is 7.

Further, it also includes filtering the mixed solution after shaking with a 0.22 μm membrane filter.

Compared with the prior art, the beneficial effects of the present invention are:

(1) The present invention takes tris(4-(1H-imidazol-1-yl)phenyl)amine as monomer and quaternization reaction with 1,4-bis(bromomethyl)benzene to synthesize positively charged imidazolyl The group's cationic framework material ImCOP.

(2) The imidazolyl-based cationic framework material ImCOP synthesized by the present invention contains abundant functional groups such as imidazole and tertiary amine, which can selectively combine with ReO ₄ ^- and increase the adsorption capacity of ReO ₄ ^- .

(3) The imidazolyl cationic framework material ImCOP synthesized by the present invention contains a hydrophobic benzene ring and an imidazole group to form a hydrophobic skeleton, and has high selectivity to ⁹⁹ TcO ₄ ^- /ReO ₄ ^- with low charge density.

(4) Tris(4-(1H-imidazol-1-yl)phenyl)amine used in the present invention is a flexible tripod ligand, so that the synthesized ImCOP is a semi-rigid structure, which has High chemical stability.

(5) The method for synthesizing imidazolyl cationic framework material ImCOP of the present invention is simple, low in cost, environmentally friendly and economical and efficient, and has high adsorption capacity and high speed for ReO ₄ ^- ; and, ImCOP has excellent cycle performance, which is beneficial to ecological The sustainable development of the environment is expected to be used for the removal of ⁹⁹ TcO ₄ ^- .

Description of drawings

Figure 1 is a schematic diagram of the synthesis process of the imidazolyl cationic framework material ImCOP.

FIG. 2 is a SEM image of the imidazolyl cationic framework material ImCOP.

Figure 3 is the infrared spectrum of Tipa, BBB and ImCOP.

Fig. 4 is the infrared spectrum of imidazolyl cationic framework material ImCOP in strong acid and strong base.

Figure 5 is the adsorption isotherm diagram of the imidazolyl cationic framework material ImCOP for ReO ₄ ^- .

Fig. 6 is the adsorption kinetic diagram of imidazolyl cationic framework material ImCOP on ReO ₄ ^- .

Figure 7 is a graph showing the adsorption selectivity of imidazolyl cationic framework material ImCOP for ReO ₄ ^- in the presence of competing anions.

Fig. 8 is a graph showing the adsorption selectivity of imidazolyl cationic framework material ImCOP for ReO ₄ ^- under the condition of excess NO ₃ ^- .

Fig. 9 is a graph showing the adsorption selectivity of imidazolyl cationic framework material ImCOP for ReO ₄ ^- under the condition of excess SO ₄ ^2- .

Detailed ways

The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. The described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The methods are conventional methods unless otherwise specified. The above-mentioned raw materials can be obtained from open commercial sources unless otherwise specified. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without the prerequisite of creative work fall within the protection scope of the present invention.

Example 1: Preparation and characterization of imidazolyl cationic framework material ImCOP

0.4435 g of the imidazolyl-rich tripod flexible ligand tris(4-(1H-imidazol-1-yl)phenyl)amine (Tipa) and 0.528 g of 1,4-bis(bromomethyl)benzene (BBB ) was placed in a three-necked round-bottomed flask, then 15 mL of N,N-dimethylformamide (DMF) and 15 mL of acetonitrile were added, and the reaction mixture was obtained after mixing evenly; The solution was stirred and refluxed at 80°C for 3 days, cooled to room temperature, and the nitrogen source was removed to obtain a reaction product solution; the reaction product solution was taken out and filtered, and the precipitate was washed with N,N-dimethylformamide and absolute ethanol, and the precipitate was Vacuum dried at 60°C overnight to obtain imidazolyl cationic framework material (ImCOP).

Figure 1 is a schematic diagram of the synthesis process of the imidazolyl cationic framework material ImCOP.

FIG. 2 is a SEM image of the imidazolyl cationic framework material ImCOP. Scanning electron microscope (SEM) was used to observe the morphology of the imidazolyl cationic framework material ImCOP. It can be seen from the SEM results that ImCOP is a spherical structure with a diameter of about 2 μm.

Figure 3 is the infrared spectrum of Tipa, BBB and ImCOP. The imidazole ring of tris(4-(1H-imidazol-1-yl)phenyl)amine (Tipa) has a characteristic peak at 1024 cm ^-1 , which moves to 1072 cm ^-1 after the synthesis of imidazolyl cationic framework material ImCOP . In addition, the C-Br bond of 1,4-bis(bromomethyl)benzene (BBB) at 567 cm ^-1 disappeared in the outer infrared spectrum of ImCOP. The above infrared spectrum results show that the imidazolyl cationic framework material ImCOP has been successfully synthesized by the method of the present invention.

Fig. 4 is the infrared spectrum of imidazolyl cationic framework material ImCOP in strong acid and strong base. ImCOP was soaked in NaOH (1, 3M) and HNO ₃ (1, 3, 5M) solution for 24h respectively, and its infrared spectrum was tested. It can be seen from Figure 4 that the characteristic peak of ImCOP at 1072cm ^-1 still exists, The above results show that ImCOP has good stability under strong acid and strong alkali conditions.

Example 2: Adsorption of ReO ₄ ^- by imidazolyl cationic framework material ImCOP

(1) pH optimization

The pH of the ReO ₄ ^-solution was optimized. 10 mg of imidazolyl cationic framework material ImCOP was added to 10 mL of a solution containing 400 mg/L ReO ₄ ^- , and the pH of the solution was adjusted with HNO ₃ or NaOH (1, 3, 5, 7, 9, 11, 13) at room temperature Shake on a shaking table for 24h, filter with a 0.22μm membrane filter, detect the residual ReO ₄ -concentration in the filtrate by inductively coupled plasma mass spectrometry ^, and calculate the removal rate of imidazolyl cationic framework material ImCOP to ReO ₄ ^- . The results showed that the adsorption and removal efficiency of imidazolyl cationic framework material ImCOP for ReO ₄ ^- was over 96% in the pH range of 3-13. When the solution pH was 7, the removal efficiency of ImCOP for ReO ₄ ^- reached 99%. %above.

(2) Adsorption capacity and adsorption kinetics of ImCOP for ReO ₄ ^-

Dissolve sodium perrhenate in deionized water to prepare perrhenate solutions of different concentrations (50-2000mg/L), adjust the pH of the solution to 7 with HNO ₃ or NaOH, and add 10 mg of imidazole to 10 mL of ReO ₄ ^-solution The cationic framework material ImCOP was shaken at room temperature for 24h on a shaking table, filtered with a 0.22 μm membrane filter, and the residual ReO ₄ -concentration in the filtrate was detected by inductively coupled plasma mass spectrometry ^. ₄ ^- The adsorption capacity. Due to the large driving force of the concentration gradient at the solid-liquid interface, the adsorption capacity of the imidazolyl cationic framework material ImCOP for ReO ₄ ^- increased with the increase of the ReO ₄ ^- concentration until the adsorption equilibrium was reached. Figure 5 is the adsorption isotherm diagram of the imidazolyl cationic framework material ImCOP for ReO ₄ ^- . It can be seen from Figure 5 that the maximum adsorption capacity of the imidazolyl cationic framework material ImCOP for ReO ₄ ^- is 1162 mg/g. Fig. 6 is the adsorption kinetic diagram of imidazolyl cationic framework material ImCOP on ReO ₄ ^- . It can be seen from Figure 6 that the adsorption capacity of the imidazolyl cationic framework material ImCOP for ReO ₄ ^- increases with the extension of the adsorption time. When the adsorption time is 2 min, the imidazolyl cationic framework material ImCOP is the adsorption of ReO ₄ ^- . It reaches saturation and it is very fast.

(3) Selectivity of ImCOP for ReO ₄ ^-adsorption

10 mg of imidazolyl cationic framework material ImCOP was added to 10 mL of ReO ₄ ^- solution containing 0.1 mM, and 0.1 mM of common coexisting anions in nuclear waste (SO ₄ ^2- , NO ₃ ^- , PO ₄ ^3- , CO ₃ ^2- , Cl ^- ) solution, the mixed solution was shaken at room temperature for 24 hours, filtered with a 0.22 μm membrane filter, the residual ReO ₄ ^- concentration in the filtrate was detected by inductively coupled plasma mass spectrometry, and the imidazolyl cationic framework was investigated. Selectivity of material ImCOP for ReO ₄ ^-adsorption . Figure 7 is a graph showing the adsorption selectivity of imidazolyl cationic framework material ImCOP for ReO ₄ ^- in the presence of competing anions. It can be seen from Figure 7 that the adsorption and removal rate of ImCOP for ReO ₄ ^- is nearly 100%, and under the condition of the coexistence of other anions, the adsorption and removal rate of ImCOP for ReO ₄ ^- is about 96%, indicating that ImCOP has high selectivity for ReO ₄ ^- adsorption .

There is often a large excess of NO ₃ ^- and SO ₄ ^2- in nuclear waste. The selectivity of the imidazolyl cationic framework ImCOP for ReO ₄ ^-adsorption was investigated under the condition of excess NO ₃ ^- and SO ₄ ^2- . 10 mg of imidazolyl cationic framework material ImCOP was added to 10 mL of ReO ₄ ^-solution containing 0.1 mM, and then NaNO ₃ (0.1 mM, 1 mM, 10 mM, 100 mM) or Na ₂ SO ₄ (0.1 mM, 1 mM) were added with different concentrations. , 10mM, 100mM, 600mM) solution, the mixture was shaken at room temperature for 24h, filtered with a 0.22μm membrane filter, and the residual ReO ₄ -concentration ⁱⁿ the filtrate was detected by inductively coupled plasma mass spectrometry. Fig. 8 is a graph showing the adsorption selectivity of imidazolyl cationic framework material ImCOP for ReO ₄ ^- under the condition of excess NO ₃ ^- . It can be seen from Figure 8 that when the molar ratio of NO ₃ ^- : ReO ₄ ^- is 100:1 and 500:1, the removal rates of ReO ₄ ^- by the imidazolyl cationic framework material ImCOP are 92.6% and 74.3%, respectively. Fig. 9 is a graph showing the adsorption selectivity of imidazolyl cationic framework material ImCOP for ReO ₄ ^- under the condition of excess SO ₄ ^2- . It can be seen from Figure 9 that when SO ₄ ^2- is in excess of 6000 times, the removal rate of ReO ₄ ^- by the imidazolyl cationic framework material ImCOP can still reach 74%. Therefore, the imidazolyl cationic framework material ImCOP has good adsorption selectivity for ReO ₄ ^- , which may be because the high density of aromatic substituents makes the surface of ImCOP hydrophobic, which is more conducive to the selective adsorption of ReO ₄ ^- with relatively low charge density.

Example 3: Recycling performance of ImCOP

150 mg of imidazolyl cationic framework material ImCOP was added to 150 mL of a solution containing 28 mg/L of ReO ₄ ^- at pH 7, the mixture was shaken at room temperature for 24 h, 1 mL of the mixture was taken and filtered with a 0.22 μm membrane filter, and the mixture was filtered through a 0.22 μm membrane filter. The residual ReO ₄ ^- concentration in the filtrate was detected by inductively coupled plasma mass spectrometry, and the removal rate of ReO ₄ ^- by ImCOP was calculated. The remaining mixed solution was washed with deionized water, filtered with suction, the precipitate was collected, and vacuum-dried at 60° C. overnight to obtain 135 mg of perrhenate-supported imidazolyl cationic framework material ReO ₄ —ImCOP, which was ground and dispersed in 135 mL of 3M In the KBr solution, the dispersion was shaken at room temperature for 24 hours to elute, washed with deionized water, suction filtered, and vacuum-dried at 60 °C overnight to obtain a regenerated imidazolyl cationic framework material ImCOP for next use. The results show that after four adsorption/desorption cycles, the removal efficiency of the imidazolyl cationic framework material ImCOP to ReO ₄ ^- can still reach more than 99%, indicating that the imidazolyl cationic framework material ImCOP has good recycling performance.

It can be seen that the imidazolyl cationic framework material ImCOP prepared by the method of the present invention has good stability in strong acid and strong base, and has the advantages ^of high adsorption capacity, fast adsorption speed, good selectivity and high recycle performance for ReO _4- It is expected to be used for pertechnetate removal.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, some improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be regarded as Included in the protection scope of the present invention.

Claims (7)

1. A method for synthesizing a cationic framework material, which is characterized by comprising the following steps:

1) the molar ratio is 1: adding N, N-dimethylformamide and acetonitrile into the tris (4- (1H-imidazole-1-yl) phenyl) amine and the 1, 4-bis (bromomethyl) benzene of (1-3) and uniformly mixing to obtain a reaction mixed solution;

2) stirring and refluxing the reaction mixed solution in a nitrogen atmosphere, cooling to room temperature, and then removing a nitrogen source to obtain a reaction product solution;

3) and (3) carrying out suction filtration on the obtained reaction product solution, washing the precipitate with N, N-dimethylformamide and absolute ethyl alcohol, and drying the precipitate to obtain the imidazole-based cationic framework material ImCOP.

2. Use of the cationic framework material obtained by the synthesis method according to claim 1 for the removal of perrhenate/pertechnetate.

3. Use of a cationic framework material for perrhenate/pertechnetate removal according to claim 2, characterized in that it is applied by adding said cationic framework material to the perrhenate-containing solution to be treated, oscillating at room temperature.

4. Use of a cationic framework material for perrhenate/pertechnetate removal according to claim 3, wherein the concentration of the solution to be treated containing perrhenate is in the range of 50-2000 mg/L.

5. Use of a cationic framework material for perrhenate/pertechnetate removal according to claim 3, wherein a pH regulator is further used to adjust the pH to 1-13 before shaking at room temperature.

6. Use of a cationic framework material according to claim 5 for the removal of perrhenate/pertechnetate, wherein the pH is adjusted to 7.

7. Use of a cationic framework material for perrhenate/pertechnetate removal according to claim 3, further comprising filtering the shaken mixture through a 0.22 μm membrane filter.

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