Cationic cyclodextrin material, its preparation method and use in iodine adsorption

Abstract

The application provides a cationic cyclotriphosphazene material, a preparation method thereof and application thereof in iodine adsorption. The cationic cyclotriphosphazene material has a structure as shown in formula (I): in formula (I), X represents a coordination anion, and the anion has a charge number of 4. The cationic cyclotriphosphazene material has excellent thermal stability and chemical stability, and in particular, can be recycled, and after 5 cycles, the adsorption capacity is still maintained at more than 85% of the initial value, showing good recycling performance.

Description

Technical Field

[0001] This invention relates to the field of adsorption materials technology, and in particular to a cationic cyclophosphine material, its preparation method, and its application in iodine adsorption. Background Technology

[0002] With rapid industrialization, human demand for energy is increasing daily; however, the use of fossil fuels has led to increasingly severe global environmental pollution. Nuclear power, as a highly efficient and clean energy source with ultra-high energy density and no greenhouse gas emissions, has seen rapid development globally. It is projected that by 2030, nuclear power generation in my country (approximately 131 million kilowatts) will account for 10% of total power generation. However, nuclear waste and nuclear leaks will generate large amounts of pollutants that are difficult to decompose naturally. 129 I and 131 Class 1 radioactive iodine contaminants, among which 129 I has a long half-life (1.57 × 10⁻⁶). 7 Characteristics such as (years) and persistent toxicity, while 131 Radioactive iodine (I-) has a short half-life (8.02 days) and strong radiation, posing a significant threat to ecological security and human health. Therefore, how to treat radioactive iodine in water and air has become one of the most important issues in radioactive iodine treatment worldwide. Currently, solid-phase adsorption is the most commonly used method for iodine capture and is widely studied and applied. Traditional techniques and materials for iodine adsorption include activated carbon, zeolite, and silver-based solid adsorbents. However, the application of these adsorbents is limited due to their low adsorption capacity, low adsorption rate, poor recyclability, and weak environmental benefits. Therefore, developing new materials and technologies and finding suitable iodine capture adsorbents is crucial.

[0003] In recent years, novel porous materials such as metal-organic frameworks (MOFs) have emerged. S Covalent organic frameworks (COFs), hydrogen-bonded organic frameworks (HOFs), porous organic polymers (POPs), molecular cages, and some supramolecular macrocyclic compounds have also been used to capture iodine. Although these materials exhibit higher removal capabilities due to their tunable pore environment and much larger surface area than conventional materials, their development is limited by their high synthesis difficulty, high economic cost, weak interactions, and low thermal / chemical stability. Currently reported electron-deficient macrocyclic compounds often employ an addition reaction between an amino group and an aldehyde, followed by dehydration to obtain an imine (e.g., patent CN112174964A). However, imines are unstable and can be hydrolyzed back to amines, limiting their adsorption of iodine in aqueous solutions.

[0004] Therefore, there is a need for an adsorbent material that has a simple preparation process and exhibits good iodine adsorption performance in both the gas and aqueous phases. Summary of the Invention

[0005] The purpose of this invention is to overcome the many shortcomings of existing technologies, such as difficult preparation, low adsorption capacity, low thermal / chemical stability (e.g., hydrolysis), slow adsorption rate, and poor cycling performance, and to provide an adsorbent material with a simple preparation process and good iodine adsorption performance in both gas and aqueous phases—a new cationic cyclophosphine material.

[0006] Another object of the present invention is to provide a method for preparing the cationic cyclophosphine material.

[0007] Another object of the present invention is to provide the application of the cationic cyclophosphine material in iodine adsorption.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A cationic cyclophosphine material having a structure as shown in formula (I):

[0010]

[0011] In formula (I), X represents a coordinating anion with a charge of 4.

[0012] The cationic cyclopyridine material of this invention (abbreviated as BPy-Box·4X, where X represents the coordinating element) provides a suitable cavity size by forming a twisted quadrilateral with 3,3'-bipyridine and p-dibenzyl bromide, enhancing its performance with linear I3. - This process gives it excellent adsorption properties for iodine in both the gas and liquid phases.

[0013] Preferably, X is selected from 4PF6. - 4Cl - 4Br - 4I - 4CF3COO - 2SO4 2- At least one of them.

[0014] The preparation method of the cationic cyclophosphine material includes the following steps:

[0015] S1,3,3'-bipyridine and α,α'-dibromo-p-xylene were mixed in a solvent, heated under reflux, and then excess hexafluorophosphate was added to precipitate the product, thus giving intermediate BB1·2PF6.

[0016] S2. The intermediates BB1·2PF6 and α,α'-dibromo-p-xylene obtained in step S1 are mixed in a solvent and subjected to a reflux reaction. After the reaction is complete, a coordinating anion salt is added for an ion exchange reaction. The precipitate obtained by separation is the cationic cyclophosphide material (BPy-Box·4X).

[0017] In this invention, the solvents used in steps S1 and S2 can be the same or different. The solvents include, but are not limited to, one or a combination of several of the following: acetonitrile, dichloromethane, N,N-dimethylformamide, N,N-dimethylacetamide, dioxane, ethanol, methanol, tetrahydrofuran, mesitylene, and chloroform.

[0018] Preferably, in steps S1 and S2, the temperature of the reaction is independently selected from 0 to 150°C, and the reaction time is independently selected from 0.1 to 1000 h.

[0019] Preferably, the molar ratio of 3,3'-bipyridine to p-dibenzyl bromide in step S1 is: 3,3'-bipyridine: p-dibenzyl bromide = (1:1000) to (1000:1).

[0020] Preferably, the molar ratio of BB1·2PF6 and p-dibenzyl bromide in step S2 is BB1·2PF6: p-dibenzyl bromide = (1:100) to (100:1).

[0021] Preferably, the hexafluorophosphate includes, but is not limited to, ammonium hexafluorophosphate (NH4PF6).

[0022] In the preparation method of the present invention, the atmosphere mixed in steps S1 and S2 can be an air atmosphere or an inert gas atmosphere.

[0023] The mixing methods include, but are not limited to, stirring and ultrasonication.

[0024] This invention uses a two-step method to prepare the material, which not only improves the utilization rate of raw materials and the yield, but also makes the prepared cationic cyclophosphine material more stable, with better iodine adsorption and recycling effects.

[0025] Preferably, a catalyst may be added in step S2 as needed, including but not limited to tetrabutylammonium iodide.

[0026] Preferably, in the preparation of cationic cyclophosphine materials, the present invention may also use a template, which is added to the reaction system in step S2. The template includes, but is not limited to, aromatic compounds, such as one or a combination of several of naphthalene, anthracene, phenanthrene, and pyrene.

[0027] In this invention, the above reaction can be carried out in a closed container commonly used in the art, including but not limited to glass bottles, round-bottom flasks, or pressure-resistant bottles.

[0028] This invention also protects the application of the above-mentioned cationic cyclophosphine material in the adsorption of iodine, wherein the iodine can be iodine vapor or iodine solution.

[0029] When the cationic cyclophosphine material is used to adsorb iodine vapor, the adsorption temperature is 75±10℃ and the adsorption time is 5~2400min.

[0030] When the cationic cyclophosphamide material is used to adsorb iodine solution, the solvent of the iodine solution includes, but is not limited to, water, dichloromethane, N,N-dimethylformamide, methanol, or one or more of the above solvents; the adsorption time is 5 to 300 min.

[0031] More importantly, the cationic cyclophosphamide material of the present invention can be reused after adsorbing iodine and then desorbing it. The desorption of iodine includes the following steps: desorbing the cationic cyclophosphamide material after adsorbing iodine at a temperature of 150±20℃, or extracting it with an organic solvent and then drying it.

[0032] Preferably, the desorption time is 24 to 48 hours; the organic solvent used for desorption is a common iodine extraction solvent in the art, including but not limited to cyclohexane.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] The cationic cyclophosphine material of this invention exhibits excellent thermal and chemical stability, and in particular, it is recyclable. It demonstrates extremely high adsorption capacity, adsorption rate, and cycling performance for iodine in iodine vapor; and excellent adsorption rate and cycling performance for iodine in solution. Attached Figure Description

[0035] Figure 1 This is a synthetic route diagram for the cationic cyclophosphine material BPy-Box·4Cl in Example 2;

[0036] Figure 2 The 1H NMR spectrum of the cationic cyclophosphine material BPy-Box·4PF6 in Example 1 is shown below.

[0037] Figure 3 The carbon NMR spectrum of BPy-Box·4PF6, a cationic cyclophosphine material from Example 1;

[0038] Figure 4 The 1H NMR spectrum of the cationic cyclophosphine material BPy-Box·4Cl in Example 2 is shown below.

[0039] Figure 5 The carbon NMR spectrum of the cationic cyclophosphine material BPy-Box·4Cl in Example 2 is shown below.

[0040] Figure 6 The 1H NMR spectrum of the cationic cyclophosphine material BPy-Box·4Br in Example 3 is shown below.

[0041] Figure 7The mass spectrum of the cationic cyclophosphine material BPy-Box·4Br in Example 3 is shown below.

[0042] Figure 8 The 1H NMR spectrum of the cationic cyclophosphine material BPy-Box·4I in Example 4 is shown below.

[0043] Figure 9 In the figure, (a) shows the cationic non-porous macrocyclic organic compound prepared according to Example 1 of patent CN112174964A, and (b) shows the molecular structure of the pyridine derivative macrocyclic compound, which is a derivative of the electron-rich biphenyl aromatic macrocyclic compound used for iodine adsorption performance comparison in this invention.

[0044] Figure 10 The results of iodine adsorption performance tests of different cationic cyclophosphine materials in iodine vapor;

[0045] Figure 11 This is the electrostatic potential energy diagram of the cationic cyclophosphine material of the present invention;

[0046] Figure 12 The image shows a single crystal of the cationic cyclophosphine material of the present invention after adsorption of iodine vapor. Figure (a) is a top view and (b) is a side view, showing that two negatively charged I3 atoms can combine inside the electron-deficient cavity. - It can also be combined with multiple I3 externally. - and I2;

[0047] Figure 13 The iodine adsorption performance of the ionic cyclophosphine material in Example 2 of this invention after 5 cycles;

[0048] Figure 14 The image shows the aqueous phase iodine adsorption UV spectrum of the ionic cyclophosphine material of Example 1 of this invention.

[0049] Figure 15 The image shows a single crystal of the cationic cyclophosphide material of the present invention after adsorbing iodine in an aqueous solution. Figure (a) is a top view and (b) is a side view, showing that a negatively charged I3 can be bonded inside the electron-deficient cavity. - . Detailed Implementation

[0050] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments and accompanying drawings. However, the embodiments do not limit the invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in this invention are conventional reagents, methods, and equipment in this technical field. Unless otherwise specified, all reagents and materials used in this invention are commercially available.

[0051] Example 1

[0052] This embodiment provides a cationic cyclophosphine material BPy-Box·4PF6, which is prepared by a method including the following steps:

[0053] S1. Under reflux (temperature 105℃), 1055.8 mg of p-dibenzyl bromide (4 mmol) was dissolved in 100 mL of anhydrous acetonitrile and added via a syringe pump over 24 hours to a 50 mL round-bottom flask containing 1499.4 mg of 3,3-bipyridine (9.6 mmol) of anhydrous acetonitrile. The mixture was stirred for 36 hours. The reaction was cooled to room temperature (25℃), and the solid was obtained by filtration under reduced pressure. The solid was washed three times with acetonitrile. The solid was dissolved in 30 mL of water, and excess NH4PF6 was added. The solid precipitated, was filtered under reduced pressure, and the solid was washed three times with water. The solid was freeze-dried to obtain 2.50 g of white solid, which was the intermediate BB1·2PF6.

[0054] S2. 75 mL of anhydrous acetonitrile was added to a round-bottom flask containing 93.9 mg of intermediate BB1·2PF6, 35.1 mg of p-dibenzyl bromide, and 9.8 mg of tetrabutylammonium iodide (TBAI). The reaction mixture was stirred and refluxed at 105 °C for 2.5 days. Then, the mixture was cooled to room temperature (25 °C), and an excess of the coordinating anion salt tetrabutylammonium chloride (TBACl) was added for an ion exchange reaction, precipitating a large amount of solid. The solid was then collected by centrifugation, washed three times with water, and purified as follows: The solid was dissolved in 20 mL of methanol (MeOH), and 2 mL of trifluoroacetic acid (TFA) and 2 g of diatomaceous earth were added. The mixture was then subjected to rotary distillation under reduced pressure. The evaporated sample was loaded dry and passed through an automated column press using a C14 column chromatography system. 18 The product was separated by elution with a gradient of acetonitrile and water containing 0.1% TFA on a reversed-phase column and concentrated to about 30 mL.

[0055] Then, after adding excess coordinating anion salt ammonium hexafluorophosphate (NH4PF6), the sample was filtered under reduced pressure, washed three times with water, and freeze-dried to obtain 104.2 mg of purified cationic cyclophosphamide material BPy-Box·4PF6, with a yield of 72%.

[0056] The product was also characterized by nuclear magnetic resonance (NMR), and the resulting product was characterized by a hydrogen NMR spectrum as follows: Figure 2 As shown, the carbon NMR spectrum is as follows: Figure 3 As shown, the successful synthesis of the cationic cyclophosphine material BPy-Box·4PF6 is demonstrated.

[0057] Example 2

[0058] This embodiment provides a cationic cyclophosphine material BPy-Box·4Cl, the synthetic route of which is as follows: Figure 1As shown in Example 1, 104.2 mg of BPy-Box·4PF6 prepared in Example 1 was further dissolved in 30 mL of acetonitrile, and an excess (1 g in this example) of the coordinating anion salt TBACl was added. A large amount of solid precipitated, which was filtered under reduced pressure, washed three times with acetonitrile, and dried under vacuum to obtain the cationic cyclophosphine material BPy-Box·4Cl. The yield of the product was 99%, and qualitative characterization is shown in [reference needed]. Figure 4 and Figure 5 .

[0059] Example 3

[0060] This embodiment provides a cationic cycloalumina material BPy-Box·4Br, prepared according to the steps of Example 1, except that in step S2, an equimolar amount of TBACl is replaced with tetrabutylammonium bromide (TBABr). The yield of the product is 98%, and qualitative characterization is shown in [reference needed]. Figure 6 and Figure 7 .

[0061] Example 4

[0062] This embodiment provides a cationic cyclophosphide material BPy-Box·4I, prepared according to the steps of Example 1, except that in step S2, an equimolar amount of TBACl is replaced with tetrabutyliodide bromide (TBAI). The yield of the product is 98%, and NMR characterization is shown below. Figure 8 .

[0063] Comparative Example 1

[0064] This comparative example provides a cationic cyclophosphine material BPy-Box·4Cl, which specifically includes the following steps:

[0065] Under reflux (105°C), 1055.8 mg of p-dibenzyl bromide (4 mmol) was dissolved in 100 mL of anhydrous acetonitrile. This solution was then added via a syringe pump over 24 hours to a 50 mL round-bottom flask containing 1499.4 mg of 3,3-bipyridine (9.6 mmol), excess (1 g) of NH4PF6, and 9.8 mg of tetrabutylammonium iodide (TBAI) catalyst. The mixture was stirred for 96 hours. After cooling to room temperature (25°C), the reaction was filtered under reduced pressure to obtain a solid, which was washed three times with acetonitrile. The solid was then dissolved in 30 mL of water, and excess tetrabutylammonium chloride (TBACl) was added for an ion exchange reaction, precipitating a large amount of solid (i.e., the cationic cyclophosphide material BPy-Box·4Cl). The solid was then obtained by centrifugation, washed three times with water, and purified according to the purification steps in Example 1 to obtain the cationic cyclophosphide material BPy-Box·4Cl in 30% yield.

[0066] Application examples

[0067] The materials from the above examples and comparative examples, the cationic non-porous macrocyclic organic compound prepared according to Example 1 of patent CN112174964A, and the electron-rich biphenyl aromatic macrocyclic compound derivative—pyridine derivative macrocyclic compound (molecular structure formula see...) Figure 9 (b) was used as an adsorbent material in iodine adsorption. The iodine adsorption performance and cycle performance of the material in iodine vapor and iodine solution were tested, as follows:

[0068] 1. The adsorption performance of the above-mentioned adsorbent material in iodine vapor, wherein the iodine vapor absorption of the cationic cyclophosphine material is carried out at a temperature of 75°C (based on the reprocessing temperature of nuclear fuel):

[0069] 10 mg of adsorbent material was placed into pre-weighed 2 mL glass vials, which were then placed in a sealed 20 mL glass bottle containing 500 mg of iodine. The bottle was placed in a 75°C oven. At specific time points within the 0–40 h range (e.g., 0 h, 1 h, 2 h…15 h, 20 h, 25 h, 35 h, 40 h, etc.), the bottles were weighed after iodine adsorption to determine the amount of iodine adsorbed. (Adsorption test results are available.) Figure 10 And Table 1.

[0070] Data show that the iodine adsorption of the four cationic cyclophosphamide materials prepared in Examples 1-4 of this invention basically reached equilibrium after 15 hours, with BPy-Box·4PF6 having an adsorption capacity of 2.38 g. -1 The adsorption capacity of BPy-Box·4I was 2.46 g. -1 The adsorption capacity of BPy-Box·4Br was 3.04 g / g. -1 The adsorption capacity of BPy-Box·4Cl was 3.99 g / L. -1 Compared to pyridine derivatives, which are derivatives of electron-rich biphenyl aromatic macrocyclic compounds, pyridine nitrogen undergoes nucleophilic substitution to form pyridine salts, improving its solubility in aqueous solutions. However, its primary recognition and bonding targets remain electron-deficient compounds, such as viologen molecules and toxic cationic derivatives like o-phenanthroline. The cationic cyclophosphine material prepared in this invention is entirely electron-deficient, enabling efficient interaction with iodine both outside and inside the cavity (see...). Figure 12 ).

[0071] 2. The above-mentioned iodine-adsorbing material was placed in a vacuum oven at 150°C for 36 hours for desorption, and the iodine adsorption experiment was conducted again. The adsorbed iodine... Figure 13 Table 1 shows the iodine adsorption performance after 5 cycles. The experiment shows that the cationic cyclophosphine material of the present invention still retains more than 85% of the initial adsorption capacity after 5 cycles, demonstrating good recycling performance.

[0072] 3. Study on the adsorption performance of the above-mentioned adsorbent materials in iodine aqueous solution:

[0073] Add 5 mg of the above adsorbent material to 5 mL of saturated iodine aqueous solution, shake well, let stand, and measure the ultraviolet absorption spectrum of the solution at specific time points within the range of 0–300 min. (Appendix) Figure 14 This is the UV spectrum of iodine adsorption in the aqueous phase. Experiments show that after 300 minutes, more than 90% of the iodine is adsorbed by the cyclophosphamide material, demonstrating good iodine adsorption efficiency in the aqueous phase. Figure 15 This is a single-crystal image of the cationic cyclophosphide material of the present invention after adsorption of iodine vapor, showing that a negatively charged I3 can be bonded inside the electron-deficient cavity. - .

[0074] Table 1. Adsorption performance test results of different adsorbent materials

[0075]

[0076] The results above show that:

[0077] The cationic cyclophosphine material prepared by this invention has excellent thermal and chemical stability, and in particular, it can be recycled. The cationic cyclophosphine material of this invention retains more than 85% of its initial adsorption capacity after 5 cycles, demonstrating good recycling performance.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A cationic cyclophosphine material, characterized in that, It has a structure as shown in equation (I): Formula (I) In formula (I), X represents a coordinating anion with a charge of 4; X is selected from 4PF6. - 4Cl - 4Br - Or 4I - .

2. The method for preparing the cationic cyclophosphine material according to claim 1, characterized in that, Includes the following steps: S1. 3,3'-bipyridine and α,α'-dibromo-p-xylene were mixed in a solvent, heated under reflux, and then excess hexafluorophosphate was added to precipitate the product, thus obtaining the intermediate. S2. The intermediate obtained in step S1 and α,α'-dibromo-p-xylene are mixed in a solvent and then subjected to a reflux reaction. After the reaction is complete, a coordinating anion salt is added to carry out an ion exchange reaction. The precipitate obtained at the end is the cationic cyclophosphide material. The coordinating anion salt is selected from tetrabutylammonium chloride, ammonium hexafluorophosphate, tetrabutylammonium bromide or tetrabutylammonium iodide.

3. The preparation method according to claim 2, characterized in that, The molar ratio of 3,3'-bipyridine to p-dibenzyl bromide in step S1 is: 3,3'-bipyridine: p-dibenzyl bromide = (1:1000) ~ (1000:1).

4. The preparation method according to claim 2, characterized in that, The molar ratio of the intermediate and p-dibenzyl bromide in step S2 is intermediate: p-dibenzyl bromide = (1:100) ~ (100:1).

5. The preparation method according to claim 2, characterized in that, The temperature of the reaction in steps S1 and S2 is independently 105~150℃, and the reaction time is independently 0.1~1000h.

6. The preparation method according to claim 2, characterized in that, The solvents mentioned in steps S1 and S2 are independently selected from one or more of acetonitrile, dichloromethane, N,N-dimethylformamide, N,N-dimethylacetamide, dioxane, ethanol, methanol, mesitylene, and chloroform; Alternatively, step S2 may also include a catalyst, wherein the catalyst is tetrabutylammonium iodide.

7. The application of the cationic cyclophosphine material according to claim 1, characterized in that, The cationic cyclophosphine material is used to adsorb iodine, wherein the iodine is iodine vapor or iodine solution.

8. The application according to claim 7, characterized in that, The cationic cyclophosphine material is used to adsorb iodine vapor at an adsorption temperature of 75±10℃ and an adsorption time of 5~2400min.

9. The application according to claim 7, characterized in that, The cationic cyclophosphine material is used to adsorb iodine solution, wherein the solvent of the iodine solution is selected from one or a combination of several of water, dichloromethane, N,N-dimethylformamide or methanol; the adsorption time is 5~300 min.

10. The application according to any one of claims 7 to 9, characterized in that, The cationic cyclophosphine material can be reused after adsorbing iodine and then desorbing it. The desorption of iodine includes the following steps: After the cationic cyclophosphamide material adsorbed with iodine was desorbed at 150±20℃, it was extracted with an organic solvent and then dried.

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