Preparation method of novel ionic pyridyl covalent organic framework material and application of novel ionic pyridyl covalent organic framework material in iodine adsorption

Abstract

The invention discloses a novel ionic pyridyl covalent organic framework material and application thereof in iodine adsorption. According to the invention, an ionic pyridyl group is introduced into the structure of the covalent organic framework material, and the covalent organic framework material is applied to iodine adsorption. The I-coated COF-DMPD-1 can induce iodine molecules to form polyiodide anions through iodide ions, and meanwhile, electrostatic interaction is formed between the formed polyiodide anions and a cation skeleton, so that the I-coated COF-DMPD-1 has high adsorption performance on iodine. The I (at) COF-DMPD-1 has a high adsorption rate on iodine in high-temperature iodine vapor, and the adsorption capacity of the I (at) COF-DMPD-1 on iodine is as high as 8.92 g / g. The I-coated COF-DMPD-1 has the advantages of high adsorption capacity, high adsorption rate and cyclic adsorption, and is suitable for adsorbing and separating radioactive iodine in the fields of nuclear industry and environmental pollution.

Description

Technical Field

[0001] The invention relates to a preparation method of a novel ionic pyridine-based covalent organic framework material and application thereof in iodine adsorption, belonging to the adsorption and separation direction in the field of new materials. Background Art

[0002] As human society's demand for energy continues to grow, nuclear energy is widely used as a clean energy source. As of 2020, nuclear energy provides 10% of the world's electricity. According to the International Atomic Energy Agency, by 2050, global electricity generation is expected to double, and nuclear power generation will account for about 12% of global electricity generation. However, with the continuous development of nuclear energy, the generation of nuclear waste is also increasing. In addition, nuclear fuel contains a large amount of raw uranium and a large amount of solid and gaseous radioactive elements produced by nuclear fission. If they are not recovered and treated, they will cause serious harm to the ecological environment and human health. Compared with solid radioactive pollutants, gaseous radioactive pollutants have great mobility and are easy to migrate with the air flow, so their pollution area is larger and the harm is stronger. Radioactive iodine is the most important radioactive pollutant in gaseous radioactive nuclear waste. Studies on nuclear accidents such as Chernobyl and Fukushima have shown that radioactive iodine pollutants are the most harmful among many radioactive substances. At present, researchers generally use dry phase dust removal, deposition, membrane separation and adsorption methods to treat radioactive iodine in the gas phase. Among them, adsorption is the most commonly used enrichment and storage method in radioactive iodine vapor, and has been widely studied and applied. Therefore, in the system of iodine vapor, designing and screening adsorption materials with simple preparation methods and high adsorption performance for iodine enrichment and storage is a research direction with important practical significance.

[0003] Covalent organic frameworks (COFs) have the advantages of high specific surface area, high porosity, functional controllability, and structural designability. They show excellent performance in gas adsorption and separation, liquid phase adsorption, catalysis, electrochemistry, and other fields, and are considered to be a new chemical material with industrial application prospects. The strategy for constructing ideal COFs with high iodine adsorption performance requires COFs to have high specific surface area, high porosity, dense active sites, and active sites with strong forces on iodine. This patent is based on the traditional nitrogen-rich pyridine structure that has a strong force on iodine molecules. Further ionization to form polyiodine anions and the formation of stronger electrostatic forces between the cationic skeleton of the COF material are beneficial to improving the adsorption capacity of COF materials for iodine. Therefore, the preparation of ligands with ionic pyridyl structures and the derived ionic pyridyl COFs are very suitable for iodine adsorption applications. Therefore, we prepared a new type of ionic pyridyl covalent organic framework material for iodine adsorption applications, and it is expected that this type of material has the advantages of high adsorption capacity, high adsorption rate, and recyclability for iodine adsorption. Summary of the invention

[0004] The purpose of the present invention is to provide a preparation method of a novel ionic pyridine-based covalent organic framework material and its iodine adsorption application. The present invention prepares I@COF-DMPD-1 material, and the prepared I@COF-DMPD-1 has the advantages of high specific surface area, high porosity and strong action on iodine molecules. The prepared I@COF-DMPD-1 adsorbent not only has the advantages of thermal stability, simple synthesis route, mild reaction conditions, simple adsorption process, etc., but also the I@COF-DMPD-1 material exhibits very high adsorption performance and regeneration performance in iodine vapor.

[0005] The technical solution of the present invention is as follows: A new type of ionic pyridine-based covalent organic framework material I@COF-DMPD-1 was prepared according to the following method: In a 100 ml reactor, 2,5-dimethylpyridine (TTP), triphenylaldehyde (TPA), potassium hydroxide, trimethylbenzene and dioxane were placed in the reactor and ultrasonicated for a period of time until dissolved. The reaction system was then heated in an oven for a period of time. After the reaction was completed, it was cooled and centrifuged, washed with DMF, THF, water and ethanol several times, and vacuum dried at 100°C to obtain milky white COF-DMPD-1. The prepared COF-DMPD-1 was placed in a 20 ml glass bottle, and then stirred in a mixed solution of CH3I and chloroform for several days, taken out, washed with chloroform first, then washed with ethanol, and vacuum dried at 100 °C to obtain milky white I@COF-DMPD-1; The mixed volume of trimethylbenzene and dioxane is 40-80 ml; The volume ratio of trimethylbenzene to dioxane is 1:0.1-10; The molar ratio of TTP:TPA is 1:0.1-10; The concentration of TPA dissolved in the mixed solution is 0.02-0.15 mol / L; The concentration of potassium hydroxide in the mixed solution is 0.1-50 mg / ml; The reaction temperature is 100°C-200°C; The COF-DMPD-1 reaction time is 1-7 days.

[0006] The molar amount of the iodomethane is 1-20 mmol; The volume of the chloroform is 1-20 ml; The reaction time of the I@COF-DMPD-1 is 1-5 days.

[0007] Compared with the prior art, the present invention has the following substantial advantages: (1) The present invention successfully designed and prepared a new type of ionic pyridine-based covalent organic framework material I@COF-DMPD-1. The COF material has a simple synthesis route, a large adsorption capacity, and can be reused, achieving the goal of adsorbing iodine from iodine vapor; (2) The novel ionic pyridine-based COF material I@COF-DMPD-1 prepared by the present invention has a uniform structure, which is conducive to dispersed adsorption; (3) I@COF-DMPD-1 has excellent thermal stability and is suitable for iodine adsorption experiments at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a schematic diagram of the structure of I@COF-DMPD-1 in Example 1 of the present invention; Figure 2 is a BET schematic diagram of I@COF-DMPD-1 in Example 1 of the present invention; Figure 3 is an XRD schematic diagram of I@COF-DMPD-1 in Example 1 of the present invention; Figure 4 is a TGA schematic diagram of I@COF-DMPD-1 in Example 1 of the present invention; Figure 5 This is a schematic diagram of the adsorption kinetics of iodine by I@COF-DMPD-1 in Example 1 of the present invention; Figure 6 This is a test diagram of the cyclic performance of I@COF-DMPD-1 to iodine vapor in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0009] The present invention is described in detail below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments. Without departing from the content and scope of the present invention, changes in implementation should be included in the technical scope of the present invention.

[0010] Example 1: Preparation of I@COF-DMPD-1 In a 100 ml reactor, 2,5-dimethylpyridine (TTP) (1.5 mmol, 160.7 mg), isophthalic acid (TPA) (1 mmol, 162.2 mg), potassium hydroxide (175 mg), trimethylbenzene (30 ml) and dioxane (30 ml) were placed in the reactor and ultrasonicated for a period of time until dissolved. The reaction system was then reacted in an oven at 180°C for 4 days. After the reaction was completed, it was cooled and centrifuged, washed with DMF 3 times, THF 3 times, water 3 times, and ethanol 3 times, and vacuum dried at 100°C to obtain milky white COF-DMPD-1. The prepared COF-DMPD-1 was placed in a 20 ml glass bottle and then stirred in a mixed solution of CH3I (1 mmol, 141.3 mg) and chloroform (10 ml) for 2 days. The mixture was taken out and washed with chloroform three times and then with ethanol three times. The mixture was vacuum dried at 100 °C to obtain milky white I@COF-DMPD-1.

[0011] Example 2: Preparation of I@COF-DMPD-1 In a 100 ml reactor, 2,5-dimethylpyridine (TTP) (1.5 mmol, 160.7 mg), isophthalic acid (TPA) (1 mmol, 162.2 mg), potassium hydroxide (175 mg), trimethylbenzene (40 ml) and dioxane (40 ml) were placed in the reactor and ultrasonicated for a period of time until dissolved. The reaction system was then reacted in an oven at 180°C for 4 days. After the reaction was completed, it was cooled and centrifuged, washed with DMF 3 times, THF 3 times, water 3 times, and ethanol 3 times, and vacuum dried at 100°C to obtain milky white COF-DMPD-1. The prepared COF-DMPD-1 was placed in a 20 ml glass bottle and then stirred in a mixed solution of CH3I (1 mmol, 141.3 mg) and chloroform (10 ml) for 2 days. The mixture was taken out and washed with chloroform three times and then with ethanol three times. The mixture was vacuum dried at 100 °C to obtain milky white I@COF-DMPD-1.

[0012] Example 3: Preparation of I@COF-DMPD-1 In a 100 ml reactor, 2,5-dimethylpyridine (TTP) (1.5 mmol, 160.7 mg), isophthalic acid (TPA) (1 mmol, 162.2 mg), potassium hydroxide (175 mg), trimethylbenzene (20 ml) and dioxane (40 ml) were placed in the reactor and ultrasonicated for a period of time until dissolved. The reaction system was then reacted in an oven at 180°C for 4 days. After the reaction was completed, it was cooled and centrifuged, washed with DMF 3 times, THF 3 times, water 3 times, and ethanol 3 times, and vacuum dried at 100°C to obtain milky white COF-DMPD-1. The prepared COF-DMPD-1 was placed in a 20 ml glass bottle and then stirred in a mixed solution of CH3I (1 mmol, 141.3 mg) and chloroform (10 ml) for 2 days. The mixture was taken out and washed with chloroform three times and then with ethanol three times. The mixture was vacuum dried at 100 °C to obtain milky white I@COF-DMPD-1.

[0013] Example 4: Preparation of I@COF-DMPD-1 In a 100 ml reactor, 2,5-dimethylpyridine (TTP) (1 mmol, 107.3 mg), isophthalic acid (TPA) (1 mmol, 162.2 mg), potassium hydroxide (175 mg), trimethylbenzene (30 ml) and dioxane (30 ml) were placed in the reactor and ultrasonicated for a period of time until dissolved. The reaction system was then reacted in an oven at 180°C for 4 days. After the reaction was completed, it was cooled and centrifuged, washed with DMF 3 times, THF 3 times, water 3 times, and ethanol 3 times, and vacuum dried at 100°C to obtain milky white COF-DMPD-1. The prepared COF-DMPD-1 was placed in a 20 ml glass bottle and then stirred in a mixed solution of CH3I (1 mmol, 141.3 mg) and chloroform (10 ml) for 2 days. The mixture was taken out and washed with chloroform three times and then with ethanol three times. The mixture was vacuum dried at 100 °C to obtain milky white I@COF-DMPD-1.

[0014] Example 5: Preparation of I@COF-DMPD-1 In a 100 ml reactor, 2,5-dimethylpyridine (TTP) (3 mmol, 321.4 mg), isophthalic acid (TPA) (2 mmol, 324.4 mg), potassium hydroxide (175 mg), trimethylbenzene (30 ml) and dioxane (30 ml) were placed in the reactor and ultrasonicated for a period of time until dissolved. The reaction system was then reacted in an oven at 180°C for 4 days. After the reaction was completed, it was cooled and centrifuged, washed with DMF 3 times, THF 3 times, water 3 times, and ethanol 3 times, and vacuum dried at 100°C to obtain milky white COF-DMPD-1. The prepared COF-DMPD-1 was placed in a 20 ml glass bottle and then stirred in a mixed solution of CH3I (1 mmol, 141.3 mg) and chloroform (10 ml) for 2 days. The mixture was taken out and washed with chloroform three times and then with ethanol three times. The mixture was vacuum dried at 100 °C to obtain milky white I@COF-DMPD-1.

[0015] Example 6: Preparation of I@COF-DMPD-1 In a 100 ml reactor, 2,5-dimethylpyridine (TTP) (1.5 mmol, 160.7 mg), isophthalic acid (TPA) (1 mmol, 162.2 mg), potassium hydroxide (350 mg), trimethylbenzene (30 ml) and dioxane (30 ml) were placed in the reactor and ultrasonicated for a period of time until dissolved. The reaction system was then reacted in an oven at 180°C for 4 days. After the reaction was completed, it was cooled and centrifuged, washed with DMF 3 times, THF 3 times, water 3 times, and ethanol 3 times, and vacuum dried at 100°C to obtain milky white COF-DMPD-1. The prepared COF-DMPD-1 was placed in a 20 ml glass bottle and then stirred in a mixed solution of CH3I (1 mmol, 141.3 mg) and chloroform (10 ml) for 2 days. The mixture was taken out and washed with chloroform three times and then with ethanol three times. The mixture was vacuum dried at 100 °C to obtain milky white I@COF-DMPD-1.

[0016] Example 7: Preparation of I@COF-DMPD-1 In a 100 ml reactor, 2,5-dimethylpyridine (TTP) (1.5 mmol, 160.7 mg), isophthalic acid (TPA) (1 mmol, 162.2 mg), potassium hydroxide (175 mg), trimethylbenzene (30 ml) and dioxane (30 ml) were placed in the reactor and ultrasonicated for a period of time until dissolved. The reaction system was then reacted in an oven at 150 °C for 4 days. After the reaction was completed, it was cooled and centrifuged, washed with DMF 3 times, THF 3 times, water 3 times, and ethanol 3 times, and vacuum dried at 100 °C to obtain milky white COF-DMPD-1. The prepared COF-DMPD-1 was placed in a 20 ml glass bottle and then stirred in a mixed solution of CH3I (1 mmol, 141.3 mg) and chloroform (10 ml) for 2 days. The mixture was taken out and washed with chloroform three times and then with ethanol three times. The mixture was vacuum dried at 100 °C to obtain milky white I@COF-DMPD-1.

[0017] Example 8: Preparation of I@COF-DMPD-1 In a 100 ml reactor, 2,5-dimethylpyridine (TTP) (1.5 mmol, 160.7 mg), isophthalic acid (TPA) (1 mmol, 162.2 mg), potassium hydroxide (175 mg), trimethylbenzene (30 ml) and dioxane (30 ml) were placed in the reactor and ultrasonicated for a period of time until dissolved. The reaction system was then reacted in an oven at 180°C for 2 days. After the reaction was completed, it was cooled and centrifuged, washed with DMF 3 times, THF 3 times, water 3 times, and ethanol 3 times, and vacuum dried at 100°C to obtain milky white COF-DMPD-1. The prepared COF-DMPD-1 was placed in a 20 ml glass bottle and then stirred in a mixed solution of CH3I (1 mmol, 141.3 mg) and chloroform (10 ml) for 2 days. The mixture was taken out and washed with chloroform three times and then with ethanol three times. The mixture was vacuum dried at 100 °C to obtain milky white I@COF-DMPD-1.

[0018] Example 9: Preparation of I@COF-DMPD-1 In a 100 ml reactor, 2,5-dimethylpyridine (TTP) (1.5 mmol, 160.7 mg), isophthalic acid (TPA) (1 mmol, 162.2 mg), potassium hydroxide (175 mg), trimethylbenzene (30 ml) and dioxane (30 ml) were placed in the reactor and ultrasonicated for a period of time until dissolved. The reaction system was then reacted in an oven at 180°C for 4 days. After the reaction was completed, it was cooled and centrifuged, washed with DMF 3 times, THF 3 times, water 3 times, and ethanol 3 times, and vacuum dried at 100°C to obtain milky white COF-DMPD-1. The prepared COF-DMPD-1 was placed in a 20 ml glass bottle, then stirred in a mixed solution of CH3I (2 mmol, 282.6 mg) and chloroform (10 ml) for 2 days, taken out, washed 3 times with chloroform, then washed 3 times with ethanol, and vacuum dried at 100 °C to obtain milky white I@COF-DMPD-1.

[0019] Example 10: Preparation of I@COF-DMPD-1 In a 100 ml reactor, 2,5-dimethylpyridine (TTP) (1.5 mmol, 160.7 mg), isophthalic acid (TPA) (1 mmol, 162.2 mg), potassium hydroxide (175 mg), trimethylbenzene (30 ml) and dioxane (30 ml) were placed in the reactor and ultrasonicated for a period of time until dissolved. The reaction system was then reacted in an oven at 180°C for 4 days. After the reaction was completed, it was cooled and centrifuged, washed with DMF 3 times, THF 3 times, water 3 times, and ethanol 3 times, and vacuum dried at 100°C to obtain milky white COF-DMPD-1. The prepared COF-DMPD-1 was placed in a 20 ml glass bottle, then stirred in a mixed solution of CH3I (1 mmol, 141.3 mg) and chloroform (20 ml) for 2 days, taken out, washed 3 times with chloroform, then washed 3 times with ethanol, and vacuum dried at 100 °C to obtain milky white I@COF-DMPD-1.

[0020] Example 11: Preparation of I@COF-DMPD-1 In a 100 ml reactor, 2,5-dimethylpyridine (TTP) (1.5 mmol, 160.7 mg), isophthalic acid (TPA) (1 mmol, 162.2 mg), potassium hydroxide (175 mg), trimethylbenzene (30 ml) and dioxane (30 ml) were placed in the reactor and ultrasonicated for a period of time until dissolved. The reaction system was then reacted in an oven at 180°C for 4 days. After the reaction was completed, it was cooled and centrifuged, washed with DMF 3 times, THF 3 times, water 3 times, and ethanol 3 times, and vacuum dried at 100°C to obtain milky white COF-DMPD-1. The prepared COF-DMPD-1 was placed in a 20 ml glass bottle, then stirred in a mixed solution of CH3I (1 mmol, 141.3 mg) and chloroform (10 ml) for 1 day, taken out, washed 3 times with chloroform, then washed 3 times with ethanol, and vacuum dried at 100 °C to obtain milky white I@COF-DMPD-1.

[0021] Example 12: Adsorption of iodine vapor by I@COF-DMPD-1 Before the experiment, all I@COF-DMPD-1 samples and glass containers of Examples 1-11 were thoroughly vacuum degassed and dried, and then 15 mg I@COF-DMPD-1 and excess iodine were added to two 20 ml sample bottles, respectively. The two sample bottles were placed in a sealable glass container at the same time, sealed, and placed in a 75°C oven for heating. The bottles were taken out at regular time intervals, cooled to room temperature, and the change in mass of I@COF-DMPD-1 before and after iodine adsorption was weighed.

[0022] The iodine vapor adsorption experiment shows that the I@COF-DMPD-1 of Example 1 has a very high adsorption performance for iodine, and its adsorption amount can reach 8.92 g / g. This patent not only develops a new type of ionic pyridine-based covalent organic framework material, but also has a very high adsorption performance for iodine.

[0023] Example 13: Cyclic performance test of regenerated I@COF-DMPD-1 for iodine vapor adsorption After selecting I@COF-DMPD-1 of Example 1 for iodine adsorption test, take 200 mg of I@COF-DMPD-1 after adsorbing iodine vapor (referred to as I2-I@COF-DMPD-1) and stir with 500 ml of ethanol at room temperature for 12 hours, wash 3 times, and filter out. Dry under vacuum at 100°C, and weigh the change in weight percentage of I@COF-DMPD-1 before and after iodine desorption. Reuse the desorbed material in the iodine adsorption experiment, and measure at least 6 times in a cycle; After 6 cycles of adsorption in iodine vapor, the maximum adsorption capacity of I@COF-DMPD-1 can still maintain more than 99% of its original maximum adsorption capacity.

[0024] Of course, the above specific embodiments are only detailed explanations of the corresponding technical solutions of the present invention, and are not limited to the above implementation methods. For those skilled in the art, various changes or modifications can still be made on the basis of the above embodiments. All implementation methods are not listed here, and all changes or modifications derived from the above principles or mechanisms are within the protection scope of the present invention.

Claims

1. A new type of ionic pyridine-based covalent organic framework material I@COF-DMPD-1, characterized by: The novel ionic pyridine-based covalent organic framework material is prepared according to the following method: In a 100 ml reactor, 2,5-dimethylpyridine (TTP), triphenylaldehyde (TPA), potassium hydroxide, trimethylbenzene and dioxane were placed in the reactor and ultrasonicated for a period of time until dissolved. The reaction system was then heated in an oven for a period of time. After the reaction was completed, it was cooled and centrifuged, washed with DMF, THF, water and ethanol several times, and vacuum dried at 100°C to obtain milky white COF-DMPD-1. The prepared COF-DMPD-1 was placed in a 20 ml glass bottle, then stirred in a mixed solution of CH3I and chloroform for several days, taken out, washed with chloroform first, then washed with ethanol, and vacuum dried at 100 °C to obtain milky white I@COF-DMPD-1.

2. The novel ionic pyridine-based covalent organic framework material I@COF-DMPD-1 material according to claim 1, characterized in that: The mixed volume of trimethylbenzene and dioxane is 40-80 ml, and the volume ratio of trimethylbenzene to dioxane is 1:0.1-10.

3. The novel ionic pyridine-based covalent organic framework material I@COF-DMPD-1 material according to claim 1, characterized in that: The molar ratio of TTP:TPA is 1:0.1-10, and the concentration of TPA dissolved in the mixed solution is 0.02-0.15 mol / L.

4. The novel ionic pyridine-based covalent organic framework material I@COF-DMPD-1 material according to claim 1, characterized in that: The concentration of potassium hydroxide in the mixed solution is 0.1-50 mg / ml.

5. The novel ionic pyridine-based covalent organic framework material I@COF-DMPD-1 material according to claim 1, characterized in that: The reaction temperature is 100°C-200°C.

6. The novel ionic pyridine-based covalent organic framework material I@COF-DMPD-1 material according to claim 1, characterized in that: The COF-DMPD-1 reaction time is 1-7 days.

7. The novel ionic pyridine-based covalent organic framework material I@COF-DMPD-1 material according to claim 1, characterized in that: The molar amount of the iodomethane is 1-20 mmol.

8. The novel ionic pyridine-based covalent organic framework material I@COF-DMPD-1 material according to claim 1, characterized in that: The volume of the chloroform is 1-20 ml.

9. The novel ionic pyridine-based covalent organic framework material I@COF-DMPD-1 material according to claim 1, characterized in that: The reaction time of the I@COF-DMPD-1 is 1-5 days.

10. The novel ionic pyridine-based covalent organic framework material I@COF-DMPD-1 material according to claim 1, characterized in that: The adsorption capacity of I@COF-DMPD-1 in iodine vapor reaches 8.92 g / g. After 6 cycles of adsorption in iodine vapor, the maximum adsorption capacity of I@COF-DMPD-1 can still maintain more than 99% of its original maximum adsorption capacity.

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