Preparation method of crown ether covalent organic framework material and iodine adsorption application of crown ether covalent organic framework material

Abstract

The invention provides a preparation method of a crown ether covalent organic framework material and application of the crown ether covalent organic framework material in iodine adsorption. According to the invention, the octadecacrown-6 ether group is introduced into the structure of the covalent organic framework material for iodine adsorption work. The covalent organic framework material can form a one-dimensional pore channel structure in order, and meanwhile, the octadecacrown-6 ether can be selectively complexed with iodine molecules, so that the purpose of efficient iodine adsorption is achieved. The material can perform specific iodine adsorption from high-temperature iodine vapor, the iodine vapor adsorption capacity of the COF material reaches up to 5.56 g / g, and the COF material is high in adsorption capacity, easy to prepare, simple to operate, high in adsorption efficiency and particularly suitable for adsorbing and separating radioactive iodine in the nuclear industry.

Description

Technical Field

[0001] The invention relates to a preparation method of a novel covalent organic framework material with 18-crown hexaether groups, is applied to iodine adsorption, and belongs to the field of adsorption separation. Background Art

[0002] In recent years, waste from used nuclear fuel has produced iodine isotopes ( 129 I and 131 I) volatile radioactive compounds that must be removed before these waste gases are discharged. Compared with traditional treatment processes for adsorbing radioiodine and other iodine-containing compounds from waste gases, adsorption processes using porous solid adsorbents have many advantages, including simple operation, low maintenance costs, and no need to use highly corrosive solutions. Currently, various adsorbents have been developed for iodine adsorption applications, including ceramics, zeolites, aerogels, metal-organic frameworks, and other materials. As an emerging adsorbent, covalent organic framework materials (COFs) are widely used due to their low density and high porosity as well as excellent iodine adsorption capacity. Studies on iodine adsorption of COF materials have found that electron-rich adsorbents can effectively adsorb electron-deficient iodine by forming complexes. In order to prepare electron-rich adsorbents, various synthetic strategies have been developed, including the construction of π-π conjugated bonds, doping with a large number of heteroatoms, and the addition of different heterocycles (such as triazine rings, pyrazine rings, etc.). And N-containing functional groups (such as amines, imines, imidazoles, triazines, and pyridines) have been introduced into the framework structure to promote high iodine adsorption capacity.

[0003] Covalent organic frameworks (COFs) not only have stable and tunable porous structures, but also facilitate the design of functional group structures and properties. The crystallinity of COFs provides a well-regulated pore structure and the designability of active sites in the framework, which is beneficial for many applications in catalysis, adsorption and separation, including iodine adsorption. In principle, by designing suitable monomers or post-synthetic modifications, COFs can have the adsorption active sites required for functionalization, thereby obtaining a higher iodine adsorption capacity. Therefore, it is necessary to incorporate octadecanoic acid hexaether groups into the pore structure of COFs while maintaining high crystallinity and high porosity. The COF material has both a one-dimensional pore structure and octadecanoic acid hexaether groups that can complex with iodine, which can significantly improve the adsorption performance of COF materials for iodine. Summary of the invention

[0004] The purpose of the present invention is to provide a preparation method of a novel covalent organic framework material of 18-crown hexaether groups and its iodine adsorption application. The present invention prepares a COF-DB18C6 material, and the prepared COF-DB18C6 has the performance of a macroporous structure and a strong force. The prepared COF-DB18C6 adsorbent not only has the advantages of high stability, simple preparation process, mild synthesis conditions, high efficiency and rapidity, but also the COF-DB18C6 material exhibits very high adsorption performance and regeneration performance in iodine vapor.

[0005] The technical solution of the present invention is as follows: A novel 18-crown hexaether group COF-DB18C6 material is prepared according to the following method: In a 100 ml reactor, 2,5-dimethylpyrazine (TT), 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxacyclooctadecene-2,3,13,14-tetrayl)tetrabenzaldehyde (DB18C6), sodium hydroxide, trimethylbenzene and methanol 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 several times with DMF, THF, water and ethanol, and vacuum dried at 100°C to obtain light yellow COF-DB18C6.

[0006] The mixed volume of trimethylbenzene and methanol is 50-80 ml; The volume ratio of trimethylol to methanol is 1:0.5-10; The molar ratio of TT: DB18C6 is 1: 1-10; The concentration of DB18C6 dissolved in the mixed solution is 0.01-0.05 mol / L; The concentration of sodium hydroxide in the mixed solution is 1-50 mg / ml; The reaction temperature is 80°C-200°C; The reaction time is 0.5-7 days.

[0007] Compared with the prior art, the present invention has the following substantial advantages: (1) The preparation process is simple and suitable for mass production; (2) The synthesis conditions are mild and easy to prepare in a conventional synthesis environment; (3) COF-DB18C6 has high chemical and thermal stability and is suitable for iodine adsorption under different harsh conditions; (4) COF-DB18C6 has high adsorption performance for iodine and can deal with related radioactive accidents, environmental pollution and other issues. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a BET schematic diagram of COF-DB18C6 in Example 1 of the present invention; Figure 2 is an XRD schematic diagram of COF-DB18C6 in Example 1 of the present invention; Figure 3 is a TGA schematic diagram of COF-DB18C6 in Example 1 of the present invention; Figure 4 This is a schematic diagram of the adsorption kinetics of iodine by COF-DB18C6 in Example 1 of the present invention; Figure 5 This is a test diagram of the cyclic performance of COF-DB18C6 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 COF-DB18C6 In a 100 ml reactor, 2,5-dimethylpyrazine (TT) (1 mmol, 108.2 mg), 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxacyclooctadecene-2,3,13,14-tetrayl)tetrabenzaldehyde (DB18C6) (0.5 mmol, 310.2 mg), sodium hydroxide (140 mg), trimethylbenzene (30 ml) and methanol (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 light yellow COF-DB18C6.

[0011] Example 2: Preparation of COF-DB18C6 In a 100 ml reactor, 2,5-dimethylpyrazine (TT) (1 mmol, 108.2 mg), 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxacyclooctadecene-2,3,13,14-tetrayl)tetrabenzaldehyde (DB18C6) (0.5 mmol, 310.2 mg), sodium hydroxide (140 mg), trimethylbenzene (40 ml) and methanol (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 light yellow COF-DB18C6.

[0012] Example 3: Preparation of COF-DB18C6 In a 100 ml reactor, 2,5-dimethylpyrazine (TT) (1 mmol, 108.2 mg), 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxacyclooctadecene-2,3,13,14-tetrayl)tetrabenzaldehyde (DB18C6) (0.5 mmol, 310.2 mg), sodium hydroxide (140 mg), trimethylbenzene (20 ml) and methanol (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 light yellow COF-DB18C6.

[0013] Example 4: Preparation of COF-DB18C6 In a 100 ml reactor, 2,5-dimethylpyrazine (TT) (0.5 mmol, 54.1 mg), 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxacyclooctadecene-2,3,13,14-tetrayl)tetrabenzaldehyde (DB18C6) (0.5 mmol, 310.2 mg), sodium hydroxide (140 mg), trimethylbenzene (30 ml) and methanol (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 light yellow COF-DB18C6.

[0014] Example 5: Preparation of COF-DB18C6 In a 100 ml reactor, 2,5-dimethylpyrazine (TT) (1 mmol, 108.2 mg), 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxacyclooctadecene-2,3,13,14-tetrayl)tetrabenzaldehyde (DB18C6) (1 mmol, 620.4 mg), sodium hydroxide (140 mg), trimethylbenzene (30 ml) and methanol (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 dried in vacuo at 100°C to obtain light yellow COF-DB18C6.

[0015] Example 6: Preparation of COF-DB18C6 In a 100 ml reactor, 2,5-dimethylpyrazine (TT) (1 mmol, 108.2 mg), 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxacyclooctadecene-2,3,13,14-tetrayl)tetrabenzaldehyde (DB18C6) (0.5 mmol, 310.2 mg), sodium hydroxide (350 mg), trimethylbenzene (30 ml) and methanol (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 light yellow COF-DB18C6.

[0016] Example 7: Preparation of COF-DB18C6 In a 100 ml reactor, 2,5-dimethylpyrazine (TT) (1 mmol, 108.2 mg), 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxacyclooctadecene-2,3,13,14-tetrayl)tetrabenzaldehyde (DB18C6) (0.5 mmol, 310.2 mg), sodium hydroxide (140 mg), trimethylbenzene (30 ml) and methanol (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 light yellow COF-DB18C6.

[0017] Example 8: Preparation of COF-DB18C6 In a 100 ml reactor, 2,5-dimethylpyrazine (TT) (1 mmol, 108.2 mg), 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxacyclooctadecene-2,3,13,14-tetrayl)tetrabenzaldehyde (DB18C6) (0.5 mmol, 310.2 mg), sodium hydroxide (140 mg), trimethylbenzene (30 ml) and methanol (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 light yellow COF-DB18C6.

[0018] Example 9: Adsorption of iodine vapor by COF-DB18C6 Before the experiment, all COF-DB18C6 samples and glass containers of Examples 1-8 were thoroughly vacuum degassed and dried. Then, 15 mg COF-DB18C6 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. After sealing, they were placed in a 75°C oven for heating. The bottles were taken out at regular time intervals and cooled to room temperature. The change in mass of COF-DB18C6 before and after iodine adsorption was weighed.

[0019] Table 1 Iodine adsorption amount of COF-DB18C6 in Examples 1-8 Material Name Iodine adsorption (g / g) Example 1: COF-DB18C6 5.56 Example 2: COF-DB18C6 2.83 Example 3: COF-DB18C6 4.21 Example 4: COF-DB18C6 3.78 Example 5: COF-DB18C6 2.70 Example 6: COF-DB18C6 3.52 Example 7: COF-DB18C6 3.11 Example 8: COF-DB18C6 4.18 .

[0020] Example 10: Cyclic performance test of regenerated COF-DB18C6 adsorbent for iodine vapor adsorption After the COF-DB18C6 of Example 1 was used for the iodine adsorption test, 200 mg of COF-DB18C6 (referred to as I2-COF-DB18C6) after adsorbing iodine vapor was stirred with 500 ml of ethanol at room temperature for 12 hours, washed 3 times, and filtered out. The COF-DB18C6 was vacuum dried at 100°C, and the weight percentage change of COF-DB18C6 before and after iodine desorption was weighed. The desorbed material was reused in the iodine adsorption experiment, and the cycle was measured at least 5 times.

[0021] After five cycles of adsorption in iodine vapor, the maximum adsorption capacity of COF-DB18C6 can still maintain more than 99% of its original maximum adsorption capacity.

[0022] 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 18-crown hexaether group COF-DB18C6 material, Features: The novel covalent organic framework material of the 18-crown hexaether group is prepared according to the following method: In a 100 ml reactor, 2,5-dimethylpyrazine (TT), 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxacyclooctadecene-2,3,13,14-tetrayl)tetrabenzaldehyde (DB18C6), sodium hydroxide, trimethylbenzene and methanol 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 several times with DMF, THF, water and ethanol, and vacuum dried at 100°C to obtain light yellow COF-DB18C6.

2. The novel 18-crown hexaether group COF-DB18C6 material as claimed in claim 1, Features: The mixed volume of trimethylbenzene and methanol is 50-80 ml.

3. The novel 18-crown hexaether group COF-DB18C6 material as claimed in claim 1, Features: The volume ratio of trimethylbenzene to methanol is 1:0.5-10.

4. The novel 18-crown hexaether group COF-DB18C6 material as claimed in claim 1, Features: The molar ratio of TT:DB18C6 is 1:1-10.

5. The novel 18-crown hexaether group COF-DB18C6 material as claimed in claim 1, Features: The concentration of DB18C6 dissolved in the mixed solution is 0.01-0.05 mol / L.

6. The novel 18-crown hexaether group COF-DB18C6 material as claimed in claim 1, Features: The concentration of the sodium hydroxide in the mixed solution is 1-50 mg / ml.

7. The novel 18-crown hexaether group COF-DB18C6 material as claimed in claim 1, Features: The reaction temperature is 80°C-200°C.

8. The novel 18-crown hexaether group COF-DB18C6 material as claimed in claim 1, Features: The reaction time is 0.5-7 days.

9. Use of the novel 18-crown hexaether group COF-DB18C6 material as claimed in claim 1 in iodine vapor adsorption performance, It is characterized in that The adsorption capacity of the COF-DB18C6 in iodine vapor reaches 5.56 g / g.

10. Use of the novel 18-crown hexaether group COF-DB18C6 material as claimed in claim 1 in iodine vapor cycle adsorption, It is characterized in that After five cycles of adsorption in iodine vapor, the maximum adsorption capacity of the COF-DB18C6 can still maintain more than 99% of its original maximum adsorption capacity.

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