Preparation of ionic porous nitrogen-rich molecular cage and application of ionic porous nitrogen-rich molecular cage in purification of iodine-containing nuclear medical waste

Abstract

The invention discloses preparation of an ionic porous nitrogen-rich molecular cage and application of the ionic porous nitrogen-rich molecular cage in purification of iodine-containing nuclear medical waste, and the preparation method comprises the following steps: taking an ammonia or amine reagent as a bridge, taking an aldehyde or ketone reagent as a reaction monomer, adopting a Schiff base reaction principle, and utilizing a polydentate coordination mode to carry out imine condensation reaction on substances through a one-pot method to obtain the ionic porous nitrogen-rich molecular cage. Generating a porous nitrogen-rich molecular cage; then adding a reducing agent to further reduce the porous nitrogen-rich molecular cage, then combining with alkyl halide and an organic solvent, stirring, and carrying out rotary evaporation to obtain the ionic porous nitrogen-rich molecular cage. The method has the beneficial effects that a porous organic cage material with an ionic nitrogen-rich ligand is selected as an adsorbent, so that the physical and chemical properties are stable; the preparation method is simple in synthesis and high in yield, and the nitrogen-rich ligand is stable in structure, can adsorb iodine in a gas phase and iodine in a water phase, and can be recycled; the ion interference resistance is high, and the method adapts to iodine adsorption under the water phase condition that the pH is 3-11; the method can be applied to treatment of iodine in nuclear medical wastewater.

Description

Technical Field

[0001] The present invention belongs to the technical field of porous organic materials, and more specifically, relates to the preparation of an ionic porous nitrogen-rich molecular cage and its application in the purification of iodine-containing nuclear medical waste. Background Art

[0002] With the explosive growth in demand for medical isotopes, radioactive waste is increasing day by day. If it is discharged without treatment or improperly treated, the ecological environment will suffer from radioactive pollution. 129 I and 131 A large amount of radioactive iodine, including I 2 or I 3 - The liquid radioactive isotope waste produced by nuclear medicine is characterized by low toxicity, short half-life and small amount of waste liquid. At present, the treatment process of nuclear medical radioactive waste liquid in my country is mainly based on the storage decay method, and the setting of decay pool is the most commonly used method to treat nuclides with shorter half-life. 131 I radioactive waste treatment methods include: chemical precipitation, adsorption, membrane separation and ion exchange. Currently, iodine adsorbents have harsh preparation conditions, such as being obtained under specific conditions and having a slow adsorption rate, making it difficult to achieve batch preparation. Therefore, it is of great significance to develop an efficient, economical and recyclable iodine adsorbent.

[0003] As a cutting-edge type of microporous materials, porous organic molecular cages represent an innovative development in the field of microporous solid crystals. Each unit acts as a "molecular cage" with rich nanoscale cavities or channels inside, forming a highly regular and adjustable microenvironment. Therefore, they excel in the field of molecular recognition and sensing, and can specifically identify and bind to target molecules. In adsorption and separation science, these molecular cages can effectively capture specific gases, organic matter and even ions, achieving efficient selective separation and purification. In addition, due to its additional advantages such as low skeleton density, dual porosity inside and outside the cage, and abundant iodine adsorption sites. Porous organic molecular cages have the advantages of solution processing and simple operation in terms of adsorption. Summary of the invention

[0004] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0005] In order to achieve these purposes and other advantages according to the present invention, an ionic porous nitrogen-rich molecular cage is provided, having the following structural formula:

[0006]

[0007] wherein n=0-15, X represents I, Br, and R represents one or a combination of CH and N.

[0008] A method for preparing an ionic porous nitrogen-rich molecular cage: using ammonia or amine reagents as a "bridge", aldehyde or ketone reagents as reaction monomers, adopting the Schiff base reaction principle, and utilizing a multidentate coordination method to make the substance produce an imine condensation reaction through a one-pot method to generate a porous nitrogen-rich molecular cage, further reducing the molecular cage, and then combining with a halide and an organic solvent to obtain an ionic porous nitrogen-rich molecular cage through stirring and then rotary evaporation.

[0009] Preferably, the preparation method is specifically:

[0010] S1. Dissolve an amine compound in an organic solvent to prepare solution a, and dissolve an aldehyde compound in an organic solvent to prepare solution b, then add solution a to solution b and stir or ultrasonically mix; let the reaction stand for a certain time at a certain temperature, and filter, wash, and dry the obtained product to obtain a porous nitrogen-rich molecular cage (CC6) adsorption material;

[0011] S2, reducing the porous nitrogen-rich molecular cage material powder in step S1 with a reducing agent in one step;

[0012] S3, dissolving the porous nitrogen-rich molecular cage powder reduced in step S2 in an organic solvent, then dropping alkyl halide into the bottle, heating it in an oil bath for a period of time, and then performing rotary evaporation to obtain an ionic porous nitrogen-rich molecular cage (XCC6) adsorption material.

[0013] Preferably, in S1, the amine compound includes one or more of ethylenediamine, triethylenetetramine, pentamethylenediamine, triamine, and cyclohexanediamine, and the aldehyde compound includes one or more of trimesic acid, 1,3,5-tri(4-formylphenyl)benzene, terephthalaldehyde, and isophthalaldehyde.

[0014] Preferably, in S1 and S2, the organic solvent includes one or more of acetone, acetonitrile, dichloromethane, methanol, ethanol, toluene, and dimethyl sulfoxide, and the reducing agent includes one or more of ascorbic acid, lithium aluminum oxide, sodium borohydride, and zinc borohydride.

[0015] Preferably, in S1, the mass concentration of the amine compound in solution a is 0-1 g / L, the mass concentration of the aldehyde compound in solution b is 1-5 g / L, the volume of the organic solvent is 30-80 mL, and the volume ratio of solution a to solution b is 1-2:1-2; the reaction time is 48-72 h.

[0016] Preferably, in S3, the mass of the porous nitrogen-rich molecular cage adsorption material powder is 10-100 mg, the volume of the organic solvent is 5-30 mL, and the alkyl halide is added after dissolution, and the molar ratio of the two is: porous nitrogen-rich molecular cage powder: alkyl halide = 1:0.1-100, the oil bath reaction temperature is 20°C-50°C, the reaction time is 2-8h, the rotary evaporation temperature is 40-80°C, and the reaction time is 4-12h.

[0017] Preferably, in S1 and S3, a catalyst can be used during the reaction, and the catalyst is trifluoroacetic acid or acetic acid, with an analytically pure concentration and a volume of 0-2 μL.

[0018] Preferably, in S3, the alkyl halide is one or more of methyl iodide, ethyl bromide, pentane bromide, octane bromide, dodecane bromide, tetradecane bromide, and hexadecane bromide.

[0019] The invention discloses an application of an ionic porous nitrogen-rich molecular cage in the purification of iodine-containing nuclear medical waste, comprising the adsorption of iodine ions and volatile iodine in nuclear medical wastewater, wherein the adsorption temperature of volatile iodine is 25-100°C, the concentration range of volatile iodine is 1-1000 mg / L, the time is 1-10 hours, and the concentration range of iodine ions in water is 1-500 mg / L, the time is 28-48 hours.

[0020] The present invention has at least the following beneficial effects:

[0021] (1) The present invention selects a porous organic cage material with ionic nitrogen-rich ligands as an adsorbent, and the porous organic cage has stable physical and chemical properties;

[0022] (2) The porous organic cage material designed by the present invention has the advantages of simple synthesis, high yield, and stable structure of nitrogen-rich ligands. It can adsorb iodine in the gas phase and iodine in the water phase and can be recycled;

[0023] (3) The device used in the present invention does not require the addition of other chemicals to operate, does not introduce new impurities, and rarely generates subsequent waste;

[0024] (4) The material of the present invention has strong anti-ion interference ability and is suitable for adsorbing iodine under pH=3-11 aqueous phase conditions;

[0025] (5) The present invention has a wide range of applications and can treat iodine in nuclear medical waste liquid and nuclear waste gas.

[0026] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structure of a nuclear medical wastewater treatment device in Application Example 1 of the present invention;

[0028] Figure 2 This is a normal light micrograph of the ionic porous nitrogen-rich molecular cage prepared in Example 1 of the present invention;

[0029] Figure 3 This is a polarized micrograph of the ionic porous nitrogen-rich molecular cage prepared in Example 1 of the present invention;

[0030] Figure 4 This is a graph showing the removal rate of iodine solution adsorbed by the ionic porous nitrogen-rich molecular cage in Application Example 3 of the present invention;

[0031] Figure 5 iodine vapor adsorption diagram of CC6 and XCC6 in Application Example 2 of the present invention;

[0032] Figure 6 It is the adsorption capacity diagram of CC6 and XCC6 in Application Example 1 of the present invention;

[0033] Figure 7 This is a graph of the adsorption capacity of the ionic porous nitrogen-rich molecular cage at different pH values ​​in Application Example 4 of the present invention;

[0034] Figure 8 This is a structural diagram of the XCC6 adsorption material of Example 1 of the present invention;

[0035] Fig. 9 This is a structural diagram of the XCC6 adsorption material of Example 2 of the present invention;

[0036] Fig.10 This is a structural diagram of the XCC6 adsorption material of Example 3 of the present invention;

[0037] Fig.11 This is a structural diagram of the XCC6 adsorption material of Example 4 of the present invention;

[0038] Fig.12 This is a structural diagram of the XCC6 adsorption material of Example 5 of the present invention. DETAILED DESCRIPTION

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

[0040] Example 1

[0041] A method for preparing an ionic porous nitrogen-rich molecular cage comprises:

[0042] S1. Dissolve 0.192 mmol of pentamethylenediamine in 20 mL of methanol and stir evenly to obtain solution a, the concentration of solution a is 1 g / L; dissolve 0.128 mmol of 1,3,5-tri(4-formylphenyl)benzene in 20 mL of methanol and stir evenly to obtain solution b, the concentration of solution b is 2.5 g / L; then add solution a to solution b, let the sample bottle stand for reaction for 72 hours, the reaction temperature is 25°C, and the obtained product is filtered, washed, and dried to obtain the product porous nitrogen-rich molecular cage (CC6) adsorption material;

[0043] S2, the porous nitrogen-rich molecular cage material powder in step S1 is reduced in one step using a sodium borohydride reducing agent; the method is: 0.5g CC6 is dissolved in 25mL of a mixed solvent of dichloromethane and methanol (v / v=1 / 1), 0.1g sodium borohydride (NaBH) is added under vigorous stirring. 4 ), the mixed solution was reacted at room temperature for 20 hours. Then 1 mL of deionized water was added as solvent, and the reaction was continued at room temperature for 9 hours. The obtained solid product was filtered, washed, and dried to obtain the reduced CC6 adsorption material;

[0044] S3, 100 mg of the reduced CC6 adsorption material powder was dissolved in 25 mL of toluene, and then bromododecane with a molar ratio of CC6:bromododecane = 1:12 was dripped into the bottle, and heated in a 50°C oil bath for reaction for 2 h, and after complete dissolution, the mixture was crystallized by rotary evaporation at 60°C for 4 h to obtain an ionic porous nitrogen-rich molecular cage (XCC6) adsorption material, the structure of which is as follows: Figure 8 shown.

[0045] Figure 2 This is a normal light micrograph of the ionic porous nitrogen-rich molecular cage prepared in Example 1 of the present invention; Figure 3 This is a polarized micrograph of the ionic porous nitrogen-rich molecular cage prepared in Example 1 of the present invention; Figure 2-Figure 3 It can be seen that the obtained ionic porous nitrogen-rich molecular cage (XCC6) has bright birefringence, indicating good crystallinity.

[0046] Example 2

[0047] A method for preparing an ionic porous nitrogen-rich molecular cage comprises:

[0048] S1. Dissolve 0.192 mmol of diethylenetriamine in 20 mL of methanol and stir evenly to obtain solution a, the concentration of solution a is 1 g / L, dissolve 0.128 mmol of 1,3,5-tri(4-formylphenyl)benzene in 20 mL of methanol and stir evenly to obtain solution b, the concentration of solution b is 2.5 g / L; then add solution a to solution b, let the sample bottle stand for reaction for 72 hours, the reaction temperature is 25°C, and the obtained product is filtered, washed, and dried to obtain the product CC6 adsorption material;

[0049] S2, the CC6 adsorption material powder in step S1 is reduced by one step using sodium borohydride reducing agent; the method is: 0.5g CC6 is dissolved in 25mL of a mixed solvent of dichloromethane and methanol (v / v=1 / 1), 0.1g sodium borohydride (NaBH) is added under vigorous stirring. 4 ), the mixed solution was reacted at room temperature for 20 hours. Then 1 mL of deionized water was added as solvent, and the reaction was continued at room temperature for 9 hours. The obtained solid product was filtered, washed, and dried to obtain the reduced CC6 adsorption material;

[0050] S3, 100 mg of the reduced CC6 adsorption material powder was dissolved in 20 mL of toluene, and then 0.096 g of iodomethane with a molar ratio of CC6: chloropentane = 1:9 was dripped into the bottle, and heated in a 35°C oil bath for reaction for 3 hours, and after complete dissolution, the XCC6 adsorption material was crystallized by rotary evaporation at 60°C for 4 hours to obtain the XCC6 adsorption material, whose structure is as follows Fig. 9 shown.

[0051] Example 3

[0052] A method for preparing an ionic porous nitrogen-rich molecular cage comprises:

[0053] S1. Dissolve 0.192mmol 2,2-diamino-N-methyldiethylamine in 20mL methanol and stir evenly to obtain solution a, the concentration of solution a is 1g / L, dissolve 0.128mmol 1,3,5-tri(4-formylphenyl)benzene in 20mL methanol and stir evenly to obtain solution b, the concentration of solution b is 2.5g / L; then add solution a to solution b, let the sample bottle stand for reaction for 72h, the reaction temperature is 25°C, and the obtained product is filtered, washed and dried to obtain the product CC6 adsorption material;

[0054] S2, the CC6 adsorption material powder in step S1 is reduced by one step using sodium borohydride reducing agent; the method is: 0.5g CC6 is dissolved in 25mL of a mixed solvent of dichloromethane and methanol (v / v=1 / 1), 0.1g sodium borohydride (NaBH) is added under vigorous stirring. 4 ), the mixed solution was reacted at room temperature for 20 hours. Then 1 mL of deionized water was added as solvent, and the reaction was continued at room temperature for 9 hours. The obtained solid product was filtered, washed, and dried to obtain the reduced CC6 adsorption material;

[0055] S3, 100 mg of the reduced CC6 adsorbent powder was dissolved in 20 mL of toluene, and then 0.1641 g of ethyl bromide with a molar ratio of CC6: ethyl bromide = 1:6 was dripped into the bottle, and heated in an oil bath at 35°C for 3 hours to react, and after complete dissolution, the XCC6 adsorbent was crystallized by rotary evaporation at 60°C for 4 hours to obtain the XCC6 adsorbent, whose structure is as follows: Fig.10 shown.

[0056] Example 4

[0057] A method for preparing an ionic porous nitrogen-rich molecular cage comprises:

[0058] S1. Dissolve 0.192 mmol of triethylenetetramine in 20 mL of methanol and stir evenly to obtain solution a, the concentration of solution a is 1 g / L; dissolve 0.128 mmol of 1,3,5-tri(4-formylphenyl)benzene in 20 mL of methanol and stir evenly to obtain solution b, the concentration of solution b is 2.5 g / L; then add solution a to solution b, let the sample bottle stand for reaction for 72 hours, the reaction temperature is 25°C, and the obtained product is filtered, washed, and dried to obtain the product CC6 adsorption material;

[0059] S2, the CC6 adsorption material powder in step S1 is reduced by one step using sodium borohydride reducing agent; the method is: 0.5g CC6 is dissolved in 25mL of a mixed solvent of dichloromethane and methanol (v / v=1 / 1), 0.1g sodium borohydride (NaBH) is added under vigorous stirring. 4 ), the mixed solution was reacted at room temperature for 20 hours. Then 1 mL of deionized water was added as solvent, and the reaction was continued at room temperature for 9 hours. The obtained solid product was filtered, washed, and dried to obtain the reduced CC6 adsorption material;

[0060] S3, 100 mg of the reduced CC6 adsorbent material powder was dissolved in 20 mL of toluene, and then 0.183 g of bromopentane with a molar ratio of CC6: bromopentane = 1:12 was dripped into the bottle, and heated in an oil bath at 35°C for reaction for 3 hours, and after complete dissolution, the XCC6 adsorbent material was crystallized by rotary evaporation at 60°C for 4 hours to obtain the XCC6 adsorbent material, whose structure is as follows: Fig.11 shown.

[0061] Example 5

[0062] A method for preparing an ionic porous nitrogen-rich molecular cage comprises:

[0063] S1. Dissolve 0.192mmol 1,8-octanediamine in 20mL methanol and stir evenly to obtain solution a, the concentration of solution a is 1g / L, dissolve 0.128mmol 1,3,5-tri(4-formylphenyl)benzene in 20mL methanol and stir evenly to obtain solution b, the concentration of solution b is 2.5g / L; then add solution a to solution b, let the sample bottle stand for reaction for 72h, the reaction temperature is 25°C, and the obtained product is filtered, washed and dried to obtain the product CC6 adsorption material;

[0064] S2, the CC6 adsorption material powder in step S1 is reduced by one step using sodium borohydride reducing agent; the method is: 0.5g CC6 is dissolved in 25mL of a mixed solvent of dichloromethane and methanol (v / v=1 / 1), 0.1g sodium borohydride (NaBH) is added under vigorous stirring. 4 ), the mixed solution was reacted at room temperature for 20 hours. Then 1 mL of deionized water was added as solvent, and the reaction was continued at room temperature for 9 hours. The obtained solid product was filtered, washed, and dried to obtain the reduced CC6 adsorption material;

[0065] S3, 100 mg of the reduced CC6 adsorbent powder was dissolved in 20 mL of toluene, and then 0.1679 g of bromotetradecane with a molar ratio of CC6: bromotetradecane = 1:6 was dropped into the bottle, and heated in an oil bath at 35°C for 3 hours to react, and after complete dissolution, the XCC6 adsorbent was crystallized by rotary evaporation at 60°C for 4 hours to obtain the XCC6 adsorbent, whose structure is as follows: Fig.12 shown.

[0066] Example 6

[0067] A method for preparing an ionic porous nitrogen-rich molecular cage comprises:

[0068] S1. Dissolve 0.192 mmol of pentamethylenediamine in 20 mL of methanol and stir evenly to obtain solution a, the concentration of solution a is 1 g / L; dissolve 0.128 mmol of 1,3,5-tri(4-formylphenyl)benzene in 20 mL of methanol and stir evenly to obtain solution b, the concentration of solution b is 2.5 g / L; drop 0.1 μL of acetic acid into solution b, then add solution a into solution b, let the sample bottle stand for reaction for 24 hours, the reaction temperature is 25°C, and the obtained product is filtered, washed, and dried to obtain the product CC6 adsorption material;

[0069] The remaining steps are consistent with Example 1.

[0070] Comparative Example 1

[0071] A method for preparing a nitrogen-rich molecular cage, comprising:

[0072] S1. Dissolve 0.192 mmol of pentamethylenediamine in 20 mL of methanol and stir evenly to obtain solution a, the concentration of solution a is 1 g / L, dissolve 0.128 mmol of 1,3,5-tri(4-formylphenyl)benzene in 20 mL of methanol and stir evenly to obtain solution b, the concentration of solution b is 2.5 g / L; then add solution a to solution b, let the sample bottle stand for reaction for 72 hours, the reaction temperature is 25°C, and the obtained product is filtered, washed, and dried to obtain the product porous nitrogen-rich molecular cage (CC6) adsorption material.

[0073] Application Example 1

[0074] An application of an ionic porous nitrogen-rich molecular cage adsorption material to adsorb iodine solution, comprising:

[0075] 200 mg of dried XCC6 adsorbent material obtained in Example 1 and 200 mg of CC6 adsorbent material obtained in Comparative Example 1 were placed in glass chromatography columns respectively, and anhydrous ethanol was used to completely permeate the glass chromatography column containing the adsorbent material until the anhydrous ethanol completely soaked the adsorbent material; the peristaltic pump flow rate was adjusted to 5 mL / min, and iodine-containing medical wastewater (concentration 20 mg / L) was passed into the glass chromatography column with an inner diameter of 5 cm and an effective height of 20 cm, and the wastewater was collected to complete the deep purification of iodine-containing medical wastewater. Figure 1 As shown, the iodine adsorption capacity of XCC6 and CC6 is as follows Figure 6 As shown, from Figure 6 It can be seen that the iodine adsorption capacity of XCC6 reaches 428.6 mg / g, which is significantly higher than the 228.6 mg / g adsorption of CC6.

[0076] Application Example 2

[0077] An application of an ionic porous nitrogen-rich molecular cage adsorption material to adsorb iodine vapor, comprising:

[0078] 10 mg of the XCC6 adsorbent material prepared in Example 1 and 10 mg of the CC6 adsorbent material prepared in Comparative Example 1 were placed in weighing bottles, respectively. The weighing bottles were then placed in wide-mouth bottles, weighed, sealed, and placed in ovens at different temperatures (25°C, 50°C, and 75°C) for heating. The adsorption performance of the materials for iodine vapor was calculated using the gravimetric method. The adsorption capacities of XCC6 and CC6 at 75°C are shown in Table 1. Figure 5 As shown, the adsorption capacity of XCC6 is 6.74 g / g, and the adsorption capacity of CC6 is 6.0 g / g. It can be seen that the adsorption performance of XCC6 for iodine vapor is also higher than that of CC6.

[0079] Application Example 3

[0080] An application of an ionic porous nitrogen-rich molecular cage adsorption material to purify iodine-containing wastewater includes:

[0081] Take three groups of 20 mg washed and dried XCC6 adsorbent material and add 25 mL I - The concentrations of potassium iodide aqueous solution were 100 mg / L, 150 mg / L, and 200 mg / L, respectively. The pH was the pH of pure water. After the XCC6 adsorbent material was evenly mixed with the solution, it was shaken on a constant temperature shaker at a speed of 270 r / min for 48 hours. The reaction temperature was 25°C. The solid-liquid separation method was used for separation. The supernatant was measured by ultraviolet spectrophotometry at a wavelength of 227 nanometers. The results obtained were I - Concentration, taking 200mg / L as an example, the adsorption efficiency is as follows Figure 4 As shown, the removal rate reached 99% within 24 hours.

[0082] Application Example 4

[0083] An application of an ionic porous nitrogen-rich molecular cage adsorption material to purify iodine-containing wastewater includes:

[0084] Take 20 mg of the washed and dried XCC6 adsorbent material, add 25 mL of potassium iodide aqueous solution with an I concentration of 500 mg / L, and mix the XCC6 adsorbent material and the solution evenly according to pH = 3-11. Shake on a constant temperature shaker at a speed of 270 r / min for 24 hours, the reaction temperature is 25°C, separate by solid-liquid separation, take the supernatant and measure it by ultraviolet spectrophotometry at a wavelength of 227 nanometers. The adsorption capacity is as follows: Figure 7 As shown, it can be seen that there is a good adsorption effect in the pH range of 3-11, and the adsorption effect has no obvious change.

[0085] Application Example 5

[0086] A cyclic application of an ionic porous nitrogen-rich molecular cage adsorption material, comprising:

[0087] The XCC6 adsorption material after adsorption of iodine vapor in Application Example 2 was subjected to high temperature desorption at 150°C, and the solid powder obtained after desorption was dried in an oven at 100°C for 12h, and the adsorption in Application Example 2 was repeated;

[0088] The XCC6 adsorption material for adsorbing iodine waste liquid in Application Example 1 was soaked in isopropanol or ethanol for multiple times, washed with ultrapure water for multiple times, and the solid powder obtained after washing was dried in an oven at 100° C. for 12 hours, and the adsorption in Application Example 1 was repeated.

[0089] The test results show that the circulation rate of iodine vapor adsorption and iodine waste liquid adsorption of XCC6 adsorption material both reach 70%.

[0090] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. An ionic porous nitrogen-rich molecular cage, characterized in that: Has the following structural formula: wherein n=0-15, X represents I, Br, and R represents one or a combination of CH and N.

2. A method for preparing an ionic porous nitrogen-rich molecular cage as claimed in claim 1, characterized in that: Using ammonia or amine reagents as a "bridge" and aldehyde or ketone reagents as reaction monomers, the Schiff base reaction principle is adopted and multidentate coordination is used to make the substance produce an imine condensation reaction through a one-pot method to generate a porous nitrogen-rich molecular cage. The molecular cage is further reduced and then combined with a halide and an organic solvent to obtain an ionic porous nitrogen-rich molecular cage through stirring and then rotary evaporation.

3. The method for preparing the ionic porous nitrogen-rich molecular cage according to claim 2, characterized in that: The preparation method is specifically: S1, dissolving an amine compound in an organic solvent to prepare a solution a, dissolving an aldehyde compound in an organic solvent to prepare a solution b, then adding solution a to solution b and stirring or ultrasonically mixing; standing the reaction at a certain temperature for a certain time, filtering, washing, and drying the obtained product to obtain a porous nitrogen-rich molecular cage adsorption material; S2, reducing the porous nitrogen-rich molecular cage material powder in step S1 with a reducing agent in one step; S3, dissolving the porous nitrogen-rich molecular cage powder reduced in step S2 in an organic solvent, then dropping alkyl halide into the bottle, heating in an oil bath for a period of time, and then performing rotary evaporation to obtain an ionic porous nitrogen-rich molecular cage adsorption material.

4. The method for preparing the ionic porous nitrogen-rich molecular cage according to claim 3, characterized in that: In S1, the amine compound includes one or more of ethylenediamine, triethylenetetramine, pentamethylenediamine, triamine, and cyclohexanediamine, and the aldehyde compound includes one or more of trimesic acid, 1,3,5-tris(4-formylphenyl)benzene, terephthalaldehyde, and isophthalaldehyde.

5. The method for preparing the ionic porous nitrogen-rich molecular cage according to claim 3, characterized in that: In S1 and S2, the organic solvent includes one or more of acetone, acetonitrile, dichloromethane, methanol, ethanol, toluene, and dimethyl sulfoxide, and the reducing agent includes one or more of ascorbic acid, lithium aluminum oxide, sodium borohydride, and zinc borohydride.

6. The method for preparing the ionic porous nitrogen-rich molecular cage according to claim 3, characterized in that: In S1, the mass concentration of the amine compound in solution a is 0-1 g / L, the mass concentration of the aldehyde compound in solution b is 1-5 g / L, the volume of the organic solvent is 30-80 mL, and the volume ratio of solution a to solution b is 1-2:1-2; the reaction time is 48-72 h.

7. The method for preparing the ionic porous nitrogen-rich molecular cage according to claim 3, characterized in that: In S3, the mass of the porous nitrogen-rich molecular cage adsorption material powder is 10-100 mg, the volume of the organic solvent is 5-30 mL, and the alkyl halide is added after dissolution, and the molar ratio of the two is: porous nitrogen-rich molecular cage powder: alkyl halide = 1:0.1-100, the oil bath reaction temperature is 20°C-50°C, the reaction time is 2-8h, the rotary evaporation temperature is 40-80°C, and the reaction time is 4-12h.

8. The method for preparing the ionic porous nitrogen-rich molecular cage according to claim 3, characterized in that: In S1 and S3, a catalyst may be used during the reaction. The catalyst is trifluoroacetic acid or acetic acid, the concentration is analytical grade, and the volume is 0-2 ul.

9. The method for preparing the ionic porous nitrogen-rich molecular cage according to claim 3, characterized in that: In S3, the alkyl halide is one or more of methyl iodide, ethyl bromide, pentane bromide, octane bromide, dodecane bromide, tetradecane bromide, and hexadecane bromide.

10. An application of the ionic porous nitrogen-rich molecular cage as claimed in claims 1 to 9 in the purification of iodine-containing medical waste, characterized in that: It includes the adsorption of iodine ions and volatile iodine in nuclear medical wastewater. The adsorption temperature of volatile iodine is 25-100°C, the concentration range of volatile iodine is 1-1000 mg / L, the time is 1-10h, and the concentration range of iodine ions in the adsorption water is 1-500 mg / L, and the time is 28-48h.

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