Nitrogen-rich and oxygen-rich microporous polyacetal amine for adsorbing iodine and rhodamine B as well as preparation method and application of nitrogen-rich and oxygen-rich microporous polyacetal amine

Abstract

The invention provides nitrogen-rich and oxygen-rich microporous polyacetal amine for adsorbing iodine and rhodamine B as well as a preparation method and application of the nitrogen-rich and oxygen-rich microporous polyacetal amine. The nitrogen-rich and oxygen-rich microporous polyacetal amine is prepared from melamine and a benzoic acid derivative which are low in price through an acetal amine reaction. The polyacetal amine prepared by the method is a novel amorphous microporous polymer, and is synthesized in one step by adopting a solvothermal method without a catalyst. The polymer has the advantages of being simple in synthesis process, rich in nitrogen and oxygen, adjustable in content, large in specific surface area, high in adsorption capacity to iodine and rhodamine B and the like, and can be applied to the field of environmental governance such as removal and recovery of organic dye pollutant rhodamine B in radionuclide iodine and a water system.

Description

Technical Field

[0001] The invention relates to a preparation method and application of nitrogen-rich and oxygen-rich microporous polyaminal for adsorption of iodine and rhodamine B, belonging to the technical field of new materials. Background Art

[0002] With the continuous development of nuclear energy industry and textile industry, radioactive nuclides (iodine) produced by nuclear fuel processing and organic pollutant dyes (rhodamine B) discharged from wastewater bring permanent environmental pollution and cause serious harm to human health. It is particularly important to develop adsorbent materials that can effectively enrich and remove radioactive iodine and rhodamine B from the environment.

[0003] At present, the adsorption method has the advantages of simple operation, effectiveness, economy, environmental friendliness and recyclability. However, the low adsorption capacity and slow adsorption speed of common solid porous materials such as activated carbon and zeolite still cannot meet the market demand for high-performance adsorption materials, limiting the widespread application of the adsorption method in industry. Relatively speaking, porous organic polymers (POPs) have large specific surface area, uniform porosity distribution, low density, and excellent thermal / chemical stability. However, in order to replace existing adsorption materials, in addition to the performance of efficient removal of radionuclides and organic dyes, POPs still need to solve technical problems such as high preparation cost, harsh synthesis conditions and cumbersome steps. Most of the POPs reported in the literature are usually prepared by coupling reactions of rigid monomers with special stereostructures, and the polymerization process usually requires the use of expensive precious metal catalysts such as platinum and palladium. The development of a preparation method with low raw material prices, mild polymerization conditions, no catalysts and simple processes is a need to promote the market development of POPs adsorption materials.

[0004] The present invention uses melamine and benzoic acid derivatives, which are cheap in the market, as raw materials, and develops a type of nitrogen-rich and oxygen-rich novel organic microporous polymer with a high specific surface area through an acetalization reaction between an amino group and a functional monomer. The developed polymer has a high nitrogen and oxygen content, and the content is adjustable. The electron-rich aromatic groups and the nitrogen-rich and oxygen-rich polymer skeleton contained in the polymer can produce strong interactions with iodine molecules and rhodamine B molecules, effectively improving the adsorption performance of iodine and rhodamine B. In addition, the preparation method of the microporous polyacetalamine developed by the present invention is simple, can be completed in one step, does not require any metal catalyst, and has a high specific surface area, excellent thermal / chemical stability and high-efficiency adsorption performance for iodine and rhodamine B molecules, and has good application prospects in environmental management industries such as the removal and adsorption of radioactive iodine and rhodamine B. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing a nitrogen-rich and oxygen-rich microporous polyaminal for adsorption of iodine and rhodamine B. The microporous organic polymer is obtained by reacting melamine with a carboxyl-containing benzoic acid derivative. In addition to having the advantages of high specific surface area, excellent thermal / chemical stability and adjustable structural elements, the microporous organic polymer also has strong adsorption performance for iodine and rhodamine B pollutants.

[0006] The technical solution of the present invention:

[0007] A class of nitrogen-rich and oxygen-rich microporous polyaminals for the adsorption of iodine and rhodamine B, including MaPOP-1, MaPOP-2 and MaPOP-3, the chemical structures of which are shown below:

[0008]

[0009]

[0010] The preparation method of nitrogen-rich and oxygen-rich microporous polyaminal for adsorption of iodine and rhodamine B, wherein MaPOP-1, MaPOP-2 and MaPOP-3 are obtained by polymerizing melamine with benzoic acid, terephthalic acid and trimesic acid respectively, and the polymerization route is as follows:

[0011]

[0012] The specific synthesis steps are as follows:

[0013] Melamine is dissolved in an organic solvent A with benzoic acid, terephthalic acid and trimesic acid respectively, and the temperature is slowly raised to 130-180 degrees (preferably 170-180 degrees) under the protection of an inert gas, and the reaction is continued at this temperature for 24-96 hours (preferably 72-96 hours); the system is cooled to room temperature and then filtered, and the collected solid is washed with an organic solvent B, stripped for 12-48 hours, and dried to obtain MaPOP-1, MaPOP-2, and MaPOP-3 respectively.

[0014] Further, the mass volume ratio of the sum of the masses of melamine, benzoic acid, terephthalic acid or trimesic acid to the organic solvent A is 1 g / 30 ml to 1 g / 40 ml;

[0015] Furthermore, the organic solvent A is one or a mixture of two or more of N-methylpyrrolidone, dimethyl sulfoxide, diphenyl sulfone, o-dichlorobenzene, and mesitylene.

[0016] Furthermore, the organic solvent B is one or a mixture of two or more of acetone, methanol, ethanol, chlorinated hydrocarbons, ethyl acetate, and tetrahydrofuran.

[0017] Furthermore, for MaPOP-1, MaPOP-2 and MaPOP-3, the molar ratios of melamine to benzoic acid, terephthalic acid and trimesic acid in the polymerization system are 1:1.5-1:2, 1:0.75-1:1.25 and 1:0.5-1:1, respectively.

[0018] The nitrogen-rich and oxygen-rich microporous polyaminal prepared according to the above preparation method is characterized in that it can be widely used for the enrichment and removal of radioactive nuclide iodine and cationic adsorption dye rhodamine B of organic pollutants in water.

[0019] Beneficial effects of the present invention: The beneficial effects of the present invention are: 1) the microporous polyaminal provided by the present invention is synthesized in one step by a solvent thermal method, without the need for a catalyst; 2) the microporous polyaminal provided by the present invention is a new type of amorphous microporous polymer, which has the advantages of high BET specific surface area, excellent thermal and chemical stability and adjustable structure; 3) the cross-linked network structure of the microporous polyaminal provided by the present invention has a high content of high-affinity binding sites (N, O), and the oxygen atom content is adjustable; 4) the high-affinity binding sites are electron-rich heteroatoms (N, O), which increase the host-guest interaction between Lewis acidic I2 and cationic adsorption dye RhB and the POPs network, thereby greatly increasing the adsorption performance of the microporous polyaminal for iodine and rhodamine B molecules. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the infrared spectra of polymers MaPOP-1 to MaPOP-3.

[0021] Figure 2 It is the X-ray diffraction spectrum of polymers MaPOP-1 to MaPOP-3.

[0022] Figure 3 These are the nitrogen physical adsorption isotherms and pore size distribution curves of polymers MaPOP-1 to MaPOP-3 at 77 K. Among them, (a) is the nitrogen physical adsorption isotherm, and (b) is the pore size distribution curve.

[0023] Figure 4 The following are the UV absorption curves and working curves of iodine-cyclohexane solutions of different concentrations, where (a) is the UV absorption curve and (b) is the working curve.

[0024] Figure 5 The UV absorption curve and working curve of Rhodamine B aqueous solution with different concentrations. (a) is the UV absorption curve, and (b) is the working curve.

[0025] Figure 6 This is the adsorption capacity curve of polymer MaPOP-3, which shows the mass change with time when it adsorbs gaseous iodine.

[0026] Figure 7 The polymer MaPOP-3 was dissolved in iodine-cyclohexane solution (400 mg / L -1 ) in the adsorption capacity curve.

[0027] Figure 8 The polymer MaPOP-3 was dissolved in iodine-cyclohexane solution (400 mg / L -1 ) in the removal rate curve.

[0028] Fig. 9 The adsorption of polymer MaPOP-3 is 15mgL -1 Removal curve of Rhodamine B. DETAILED DESCRIPTION

[0029] The present invention is described in detail below in conjunction with specific implementations and drawings. The scope of the present invention is not limited to this embodiment, but is defined by the scope of the claims.

[0030] Example 1: Preparation of polymer MaPOP-1, comprising the following steps:

[0031] Under nitrogen protection, 0.3026 g of melamine (0.002399 mol) and 0.4395 g of benzoic acid (0.003599 mol) were added to the reaction bottle, 22.3 mL of organic solvent N-methylpyrrolidone was used as solvent, the temperature was slowly raised to 170 degrees, and the reaction was continued at this temperature for 72 hours; after the system was cooled to room temperature, the solid was collected by filtration, and then washed with organic solvents acetone, chloroform and tetrahydrofuran in sequence until the filtrate was colorless and transparent; the solid was continued to be extracted in tetrahydrofuran for 24 hours, taken out and placed in a vacuum oven for drying for 24 hours to obtain nitrogen-rich and oxygen-rich microporous polyacetal amine.

[0032] Example 2: Preparation of polymer MaPOP-1, comprising the following steps:

[0033] Under nitrogen protection, 0.3026 g of melamine (0.002399 mol) and 0.5127 g of benzoic acid (0.004198 mol) were added to the reaction bottle, 24.5 mL of organic solvent N-methylpyrrolidone was used as solvent, the temperature was slowly raised to 170 degrees, and the reaction was continued at this temperature for 72 hours; after the system was cooled to room temperature, the solid was collected by filtration, and then washed thoroughly with organic solvents acetone, chloroform and tetrahydrofuran in sequence until the filtrate was colorless and transparent; the solid was continued to be extracted in tetrahydrofuran for 24 hours, taken out and placed in a vacuum oven for drying for 24 hours to obtain nitrogen-rich and oxygen-rich microporous polyacetal amine.

[0034] Example 2: Preparation of polymer MaPOP-1, comprising the following steps:

[0035] Under nitrogen protection, 0.3026 g of melamine (0.002399 mol) and 0.5859 g of benzoic acid (0.004798 mol) were added to the reaction bottle, 26.7 mL of organic solvent N-methylpyrrolidone was used as solvent, the temperature was slowly raised to 170 degrees, and the reaction was continued at this temperature for 72 hours; after the system was cooled to room temperature, the solid was collected by filtration, and then washed with organic solvents acetone, chloroform and tetrahydrofuran in sequence until the filtrate was colorless and transparent; the solid was continued to be extracted in tetrahydrofuran for 24 hours, taken out and placed in a vacuum oven for drying for 24 hours to obtain nitrogen-rich and oxygen-rich microporous polyacetal amine.

[0036] Example 4: Preparation of polymer MaPOP-2, comprising the following steps:

[0037] Under nitrogen protection, 0.3026 g of melamine (0.002399 mol) and 0.2987 g of terephthalic acid (0.001799 mol) were added to the reaction bottle, 21.0 mL of organic solvent dimethyl sulfoxide was used as solvent, the temperature was slowly raised to 175 degrees, and the reaction was continued at this temperature for 84 hours; after the system was cooled to room temperature, the solid was collected by filtration, and then washed with organic solvents ethanol, dichloromethane and ethyl acetate in sequence until the filtrate was colorless and transparent; the solution was continued to be extracted in tetrahydrofuran for 36 hours, and the solution was taken out and placed in a vacuum oven for drying for 36 hours to obtain nitrogen-rich and oxygen-rich microporous polyacetal amine.

[0038] Example 5: Preparation of polymer MaPOP-2, comprising the following steps:

[0039] Under nitrogen protection, 0.3026 g of melamine (0.002399 mol) and 0.3985 g of terephthalic acid (0.002399 mol) were added to the reaction bottle, 24.5 mL of organic solvent dimethyl sulfoxide was used as solvent, the temperature was slowly raised to 175 degrees, and the reaction was continued at this temperature for 84 hours; after the system was cooled to room temperature, the solid was collected by filtration, and then washed with organic solvents ethanol, dichloromethane and ethyl acetate in sequence until the filtrate was colorless and transparent; the solution was continued to be extracted in tetrahydrofuran for 36 hours, and the solution was taken out and placed in a vacuum oven for drying for 36 hours to obtain nitrogen-rich and oxygen-rich microporous polyacetal amine.

[0040] Example 6: Preparation of polymer MaPOP-2, comprising the following steps:

[0041] Under nitrogen protection, 0.3026 g of melamine (0.002399 mol) and 0.4982 g of terephthalic acid (0.002999 mol) were added to the reaction bottle, 28.0 mL of organic solvent dimethyl sulfoxide was used as solvent, the temperature was slowly raised to 175 degrees, and the reaction was continued at this temperature for 84 hours; after the system was cooled to room temperature, the solid was collected by filtration, and then washed with organic solvents ethanol, dichloromethane and ethyl acetate in sequence until the filtrate was colorless and transparent; the solution was continued to be extracted in tetrahydrofuran for 36 hours, and the solution was taken out and placed in a vacuum oven for drying for 36 hours to obtain nitrogen-rich and oxygen-rich microporous polyacetal amine.

[0042] Example 7: Preparation of polymer MaPOP-3, comprising the following steps:

[0043] Under nitrogen protection, 0.3026 g of melamine (0.002399 mol) and 0.2521 g of trimesic acid (0.001199 mol) were added to the reaction bottle, and 22.2 mL of a mixture of dimethyl sulfoxide and diphenyl sulfone as a solvent (the mass ratio of dimethyl sulfoxide / diphenyl sulfone was 9:1), and the temperature was slowly raised to 180 degrees, and the reaction was continued at this temperature for 96 hours; after the system was cooled to room temperature, the solid was collected by filtration, and then washed with organic solvents acetone, dichloromethane and ethyl acetate in sequence until the filtrate was colorless and transparent; the solid was extracted in tetrahydrofuran for 48 hours, and the solid was taken out and dried in a vacuum oven for 48 hours to obtain nitrogen-rich and oxygen-rich microporous polyacetal amine.

[0044] Example 8: Preparation of polymer MaPOP-3, comprising the following steps:

[0045] Under nitrogen protection, 0.3026 g of melamine (0.002399 mol) and 0.3781 g of trimesic acid (0.001799 mol) were added to the reaction bottle, and 27.0 mL of a mixture of dimethyl sulfoxide and diphenyl sulfone as a solvent (the mass ratio of dimethyl sulfoxide / diphenyl sulfone was 9:1), and the temperature was slowly raised to 180 degrees, and the reaction was continued at this temperature for 96 hours; after the system was cooled to room temperature, the solid was collected by filtration, and then washed with organic solvents acetone, dichloromethane and ethyl acetate in sequence until the filtrate was colorless and transparent; the solid was further extracted in tetrahydrofuran for 48 hours, and the solid was taken out and dried in a vacuum oven for 48 hours to obtain nitrogen-rich and oxygen-rich microporous polyacetal amine.

[0046] Example 9: Preparation of polymer MaPOP-3, comprising the following steps:

[0047] Under nitrogen protection, 0.3026 g of melamine (0.002399 mol) and 0.5041 g of trimesic acid (0.002399 mol) were added to the reaction bottle, and 32.3 mL of a mixture of dimethyl sulfoxide and diphenyl sulfone as a solvent (the mass ratio of dimethyl sulfoxide / diphenyl sulfone was 9:1), and the temperature was slowly raised to 180 degrees, and the reaction was continued at this temperature for 96 hours; after the system was cooled to room temperature, the solid was collected by filtration, and then washed with organic solvents acetone, dichloromethane and ethyl acetate in sequence until the filtrate was colorless and transparent; the solid was further extracted in tetrahydrofuran for 48 hours, and the solid was taken out and dried in a vacuum oven for 48 hours to obtain nitrogen-rich and oxygen-rich microporous polyacetal amine.

[0048] Application performance test experiment of MaPOP-1~MaPOP-3

[0049] 1) Iodine vapor adsorption experiment of MaPOP-1~MaPOP-3

[0050] 30 mg of the MaPOP sample prepared in the embodiment is accurately weighed and placed in an open small glass bottle, and then the small glass bottle is placed in a sealed weighing bottle. The dryer contains excess solid iodine particles, and the weighing bottle is placed in an oven for heating, the temperature is maintained at 353K, and the pressure is ambient pressure. The small glass bottle is taken out at regular intervals, cooled to room temperature, and weighed and measured, and the iodine adsorption at different time intervals is obtained by the difference method. The iodine vapor adsorption amount is calculated as shown in formula (1):

[0051]

[0052] Among them, m t is the weight of MaPOP after adsorbing iodine vapor at a certain time (t), g; m0 is the initial weight of MaPOP, i.e., the weight without adsorbing iodine vapor, g.

[0053] For the convenience of distinction and memory, the MaPOP after iodine adsorption was named I2@MaPOP. The adsorption amount and adsorption time were plotted to obtain the adsorption curve.

[0054] 2) Iodine-cyclohexane solution adsorption experiment of MaPOP-1 to MaPOP-3

[0055] The iodine-cyclohexane solution adsorption experiment was carried out in cyclohexane solution. The specific operation process is as follows: First, take an appropriate amount of iodine and add it to n-hexane solution to prepare a series of different concentrations (50, 100, 150, 200, 250 mg L -1 ) of iodine-cyclohexane solution, with λ=522nm as the absorption wavelength, and detected by ultraviolet visible spectrophotometer (UV-vis) to draw a working curve.

[0056] The working curve of iodine n-hexane solution of different concentrations measured by UV-vis spectrum is y=0.00417x-0.05141, R 2 =0.9985, showing a linear correlation (Appendix Figure 5 ).

[0057] Before the experiment, all samples were degassed under vacuum at 120°C for 10 hours to fully dry and remove the impurities adsorbed in the samples. In a 5 mL glass bottle, 5 mg of the dried MaPOP prepared in the example was added to the iodine-cyclohexane solution (400 mg L -1 , 5mL). Seal and let stand. After a certain interval, take out a certain amount of solution and test the absorbance with UV-vis. Determine the amount of iodine remaining in the solution by the established working curve, and calculate the iodine removal efficiency by formula (2).

[0058]

[0059] In the formula, C t is the iodine concentration in the solution at time t after the addition of MaPOPs adsorption, mg L -1 ; C i Initial iodine concentration, mgL -1 .

[0060] 3) Adsorption test of rhodamine B (RhB) aqueous solution on MaPOP-1 to MaPOP-3

[0061] The adsorption experiment of RhB was carried out in aqueous solution. An appropriate amount of RhB was added to the RhB aqueous solution to prepare a series of concentrations (5 mg L -1 / 10mg L -1 / 15mg L -1 / 20mg L -1 / 25mg L -1 ) of RhB aqueous solution, with λ = 554nm as the absorption wavelength, using UV-visible spectrophotometer to detect, and draw the working curve of iodine n-hexane solution of different concentrations y = 0.23694x + 0.02358, R 2 =0.999, showing a linear correlation (Appendix Figure 6 ).

[0062] Before the experiment, the MaPOP sample prepared in the example was placed in a vacuum drying oven at 120°C for 10 hours. In a 5 mL glass bottle, an appropriate amount of the dried MaPOP sample (5 mg) was added, and then a rhodamine B aqueous solution (15 mg L -1, 5mL), sealed, and allowed to stand. At regular intervals, a certain sample was taken out and diluted by the same multiple, and then the absorbance was monitored by a UV-visible spectrophotometer. The concentration of residual rhodamine B in the solution was calculated using the established working curve, and the RhB removal efficiency was calculated using formula (3).

[0063]

[0064] In the formula, C t is the RhB concentration in the solution at time t after MaPOP adsorption, mg L -1 ; C i Initial RhB concentration, mgL -1 .

Claims

1. A nitrogen-rich and oxygen-rich microporous polyaminal for adsorption of iodine and rhodamine B, characterized in that: Including MaPOP-1, MaPOP-2 and MaPOP-3, the chemical structures are as follows:

2. The method for preparing a nitrogen-rich and oxygen-rich microporous polyaminal for adsorption of iodine and rhodamine B according to claim 1, characterized in that: The MaPOP-1, MaPOP-2 and MaPOP-3 are obtained by polymerizing melamine with benzoic acid, terephthalic acid and trimesic acid respectively, and the polymerization routes are as follows:

3. The preparation method according to claim 2, characterized in that: The specific synthesis steps are as follows: melamine is dissolved in an organic solvent A with benzoic acid, terephthalic acid and trimesic acid respectively, the temperature is slowly raised to 130-180 degrees under the protection of an inert gas, and the reaction is continued at this temperature for 24-96 hours; the system is cooled to room temperature and then filtered, and the collected solid is washed with an organic solvent B, extracted for 12-48 hours, and dried to obtain MaPOP-1, MaPOP-2 and MaPOP-3 respectively.

4. The preparation method according to claim 3, characterized in that: The mass volume ratio of the sum of the masses of melamine, benzoic acid, terephthalic acid or trimesic acid to the organic solvent A is 1 g / 30 ml to 1 g / 40 ml.

5. The preparation method according to claim 3, characterized in that: The organic solvent A is one or a mixture of two or more of N-methylpyrrolidone, dimethyl sulfoxide, diphenyl sulfone, o-dichlorobenzene and mesitylene.

6. The preparation method according to claim 3, characterized in that: The organic solvent B is one or a mixture of two or more of acetone, methanol, ethanol, chlorinated hydrocarbons, ethyl acetate and tetrahydrofuran.

7. The preparation method according to claim 3, characterized in that: For MaPOP-1, MaPOP-2 and MaPOP-3, the molar ratios of melamine to benzoic acid, terephthalic acid and trimesic acid in the polymerization system are 1:1.5-1:2, 1:0.75-1:1.25 and 1:0.5-1:1, respectively.

8. Use of the nitrogen-rich and oxygen-rich microporous polyaminal for iodine and rhodamine B adsorption according to claim 1, or the nitrogen-rich and oxygen-rich microporous polyaminal for iodine and rhodamine B adsorption obtained by the preparation method according to any one of claims 2 to 7, characterized in that: Used for the enrichment and removal of radioactive isotope iodine and cationic adsorption dye Rhodamine B of organic pollutants in water.

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