Nitrogen and oxygen-rich microporous polyamide for adsorption of iodine and rhodamine b, preparation method and application

Abstract

The present application provides a kind of nitrogen-rich oxygen-rich microporous polyamide for iodine and rhodamine B adsorption, preparation method and application.Nitrogen-rich oxygen-rich microporous polyamide is prepared by cheap melamine and benzoic acid derivatives through aminal reaction.The polyamide prepared by the present application is a new type of amorphous microporous polymer, which is synthesized by solvent thermal method in one step without catalyst.The polymer has the advantages of simple synthesis process, nitrogen-rich oxygen-rich and adjustable content, large specific surface area, strong adsorption capacity for iodine and rhodamine B, etc., and can be applied to the field of environmental governance such as removal and recovery of radionuclide iodine and organic dye pollutants rhodamine B in water system.

Description

Technical Field

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

[0002] With the continuous development of the nuclear power and textile industries, radioactive nuclides (iodine) produced by nuclear fuel processing and organic pollutant dyes (rhodamine B) discharged in wastewater have caused permanent environmental pollution and posed serious risks to human health. Developing adsorbent materials that can effectively enrich and remove radioactive iodine and rhodamine B from the environment is particularly important.

[0003] At present, the adsorption method has the advantages of being simple to operate, effective, economical, environmentally friendly and recyclable. However, the current common solid porous materials such as activated carbon and zeolite have low adsorption capacity and slow adsorption speed, which 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 a 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 having the ability to efficiently remove radioactive nuclides 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 currently 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 preparation methods with low raw material prices, mild polymerization conditions, no catalyst requirements and simple processes is a need to promote the market development of POPs adsorption materials.

[0004] This invention uses inexpensive melamine and benzoic acid derivatives as raw materials. Through an acetalization reaction between amino groups and functional monomers, a novel class of nitrogen- and oxygen-rich organic microporous polymers with a high specific surface area is developed. The developed polymers have high and adjustable nitrogen and oxygen content. The electron-rich aromatic groups and nitrogen- and oxygen-rich polymer backbones they contain strongly interact with iodine and rhodamine B molecules, effectively improving their adsorption properties for iodine and rhodamine B. Furthermore, the microporous polyaminal developed in this invention is prepared in a simple, one-step process without the need for any metal catalysts. Furthermore, it exhibits a high specific surface area, excellent thermal and chemical stability, and highly efficient adsorption properties for iodine and rhodamine B molecules. This makes it promising for applications in environmental remediation, such as the removal and adsorption of radioactive iodine and rhodamine B. Summary of the Invention

[0005] The present invention aims to provide a method for preparing a nitrogen-rich and oxygen-rich microporous polyaminal for iodine and rhodamine B adsorption. The microporous organic polymer is obtained by reacting melamine with a carboxyl-containing benzoic acid derivative. In addition to having the advantages of a high specific surface area, excellent thermal / chemical stability and adjustable structural elements, the microporous organic polymer also has strong adsorption properties 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 iodine and rhodamine B adsorption, including MaPOP-1, MaPOP-2 and MaPOP-3, whose chemical structures are shown below:

[0008]

[0009]

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

[0011]

[0012] The specific synthesis steps are as follows:

[0013] Melamine, benzoic acid, terephthalic acid, and trimesic acid are dissolved in organic solvent A, respectively. The temperature is slowly raised to 130-180°C (preferably 170-180°C) under inert gas protection, 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. The collected solid is washed with organic solvent B, stripped for 12-48 hours, and dried to obtain MaPOP-1, MaPOP-2, and MaPOP-3, respectively.

[0014] Furthermore, the mass volume ratio of the sum of the mass of melamine and 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 This is the infrared spectrum of polymers MaPOP-1 to MaPOP-3.

[0021] Figure 2 These are the X-ray diffraction spectra of polymers MaPOP-1 to MaPOP-3.

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

[0024] Figure 5 The following are the UV absorption curves and working curves of Rhodamine B aqueous solutions 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 change of mass over 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] Figure 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 with reference to specific embodiments and accompanying 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 flask, and 22.3 mL of organic solvent N-methylpyrrolidone was used as the 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 became colorless and transparent. The solid was further extracted in tetrahydrofuran for 24 hours, taken out and placed in a vacuum oven to dry 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 flask, and 24.5 mL of organic solvent N-methylpyrrolidone was used as the 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 became colorless and transparent. The solid was further extracted in tetrahydrofuran for 24 hours, taken out and placed in a vacuum oven to dry 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 flask, and 26.7 mL of organic solvent N-methylpyrrolidone was used as the 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 became colorless and transparent. The solid was further extracted in tetrahydrofuran for 24 hours, taken out and placed in a vacuum oven to dry 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 a reaction flask, and 21.0 mL of dimethyl sulfoxide was used as a 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 thoroughly washed with organic solvents such as ethanol, dichloromethane, and ethyl acetate in sequence until the filtrate was colorless and transparent. The solid was further extracted in tetrahydrofuran for 36 hours, and then taken out and dried in a vacuum oven 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 a reaction flask, and 24.5 mL of dimethyl sulfoxide was used as a 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 thoroughly washed with organic solvents such as ethanol, dichloromethane, and ethyl acetate in sequence until the filtrate became colorless and transparent. The solid was then extracted in tetrahydrofuran for 36 hours, and then taken out and dried in a vacuum oven 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 a reaction flask, and 28.0 mL of dimethyl sulfoxide was used as a 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 thoroughly washed with organic solvents such as ethanol, dichloromethane and ethyl acetate in sequence until the filtrate was colorless and transparent. The solid was further extracted in tetrahydrofuran for 36 hours, and then taken out and dried in a vacuum oven 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 a reaction flask, and 22.2 mL of a mixture of dimethyl sulfoxide and diphenyl sulfone was used as a solvent (the mass ratio of dimethyl sulfoxide / diphenyl sulfone was 9:1). 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 thoroughly with organic solvents such as acetone, dichloromethane and ethyl acetate in sequence until the filtrate became colorless and transparent. The solid was then extracted in tetrahydrofuran for 48 hours, and then 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 a reaction flask, and 27.0 mL of a mixture of dimethyl sulfoxide and diphenyl sulfone was used as a solvent (the mass ratio of dimethyl sulfoxide / diphenyl sulfone was 9:1). 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 thoroughly with organic solvents such as acetone, dichloromethane and ethyl acetate in sequence until the filtrate became colorless and transparent. The solid was further extracted in tetrahydrofuran for 48 hours, and then 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 a reaction flask, and 32.3 mL of a mixture of dimethyl sulfoxide and diphenyl sulfone was used as a solvent (the mass ratio of dimethyl sulfoxide / diphenyl sulfone was 9:1). 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 thoroughly with organic solvents such as acetone, dichloromethane and ethyl acetate in sequence until the filtrate became colorless and transparent. The solid was then extracted in tetrahydrofuran for 48 hours, and then 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 experiments on MaPOP-1 to MaPOP-3

[0050] 30 mg of the MaPOP sample prepared in the example was accurately weighed and placed in an open small glass bottle, which was then placed in a sealed weighing bottle. The desiccator contained excess solid iodine particles, and the weighing bottle was placed in an oven and heated at 353 K and ambient pressure. The small glass bottle was removed at regular intervals, cooled to room temperature, and weighed. The iodine adsorption at different time intervals was obtained by the differential method. The iodine vapor adsorption was 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 easy identification and memorization, the iodine-adsorbed MaPOP 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 ) in an iodine-cyclohexane solution, with λ = 522 nm 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 with different concentrations measured by UV-vis spectroscopy 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 the container and let it stand. After a certain period of time, remove a certain amount of solution and test the absorbance using UV-vis. The amount of iodine remaining in the solution is determined using the established working curve, and the iodine removal efficiency is calculated using formula (2).

[0058]

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

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

[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, followed by 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. The absorbance was then monitored using 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] Where 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 iodine and rhodamine B adsorption 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. 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, benzoic acid, terephthalic acid, and trimesic acid are dissolved in organic solvent A, respectively. The temperature is slowly raised to 130-180 degrees Celsius under inert gas protection, and the reaction is continued at this temperature for 24-96 hours. After the system is cooled to room temperature, it is filtered, and the collected solid is washed with 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, an organic pollutant in water.

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