A quaternary ammonium covalent organic polymer, a preparation method and application thereof

Abstract

This invention discloses a quaternized covalent organic polymer, its preparation method, and its applications, belonging to the field of environmental protection technology. The invention prepares a covalent organic polymer by reacting 1,3,5-tris(4-formylphenyl)benzene and 4,4'-((2,5-di(hydrazinoyl)-1,4-phenyl)yl(oxy))di(N,N,N-trimethylbutyl)amine via a Schiff base reaction. The backbone of this covalent organic polymer is modified with positively charged quaternary ammonium functional groups, making it suitable for the removal of radioactive ions from nuclear wastewater and the enrichment and recovery of low-concentration rare and dispersed strategic metals. The preparation method of this quaternized covalent organic polymer is simple, and it exhibits superior adsorption and separation performance for pertechnetate / perrhenate, making it a promising high-efficiency adsorbent for the adsorption and separation of nuclear industrial wastewater and rare and dispersed strategic metals.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection technology, specifically relating to a quaternized covalent organic polymer, its preparation method, and its application. Background Technology

[0002] Covalent organic polymers (COPs) are organic polymers formed by strong covalent bonds between carbon and other heteroatoms such as boron, oxygen, nitrogen, sulfur, and phosphorus. Their unique physicochemical properties have led to their wide application in many fields.

[0003] During nuclear industry operations, radioactive pertechnetate ions are commonly found in wastewater. These ions are chemically stable, highly mobile in water, and have a long half-life, making them difficult to remove effectively using conventional water treatment technologies. This poses a long-term safety threat to the ecological environment and human health. Due to the radiation hazards of radioactive technetium, the high barriers to experimental operation, and strict controls, the industry typically selects perrhenate ions with highly similar physicochemical properties as ideal simulants for adsorption and separation studies. Meanwhile, rhenium is a rare and dispersed strategic metal widely used in high-end fields such as aerospace, metallurgy, and chemicals. Direct discharge of rhenium from industrial production and rhenium-containing wastewater not only leads to resource loss but also causes environmental pollution problems.

[0004] Currently, the mainstream technologies for treating wastewater containing pertechnetate and perrhenate include solvent extraction, ion exchange, chemical precipitation, membrane separation, and adsorption. Among these, adsorption is the most practically valuable technology due to its simplicity, low cost, and minimal secondary pollution. However, traditional inorganic adsorbents and common organic resins have many limitations. Summary of the Invention

[0005] In view of the background art, the purpose of this invention is to provide a quaternized covalent organic polymer, its preparation method, and its applications. This invention prepares a covalent organic polymer via a Schiff base reaction. The backbone of this covalent organic polymer is modified with positively charged quaternary ammonium functional groups. It can be used for the removal of radioactive ions from nuclear wastewater and the enrichment and recovery of low-concentration rare and dispersed strategic metals, and is expected to serve as a highly efficient adsorbent in the adsorption and separation of nuclear industrial wastewater and rare and dispersed strategic metals.

[0006] This invention provides a method for preparing a quaternized covalent organic polymer, comprising the following steps: S1. Take 1,3,5-tris(4-formylphenyl)benzene (TFPB) and 4,4'-((2,5-di(hydrazinoyl)-1,4-phenyl)yl(oxy))di(N,N,N-trimethylbutyl)amine (DHTBA) as reaction raw materials, add solvent and sonicate to obtain reaction mixture; S2. The container containing the reaction mixture is degassed by a freeze-thaw cycle, sealed with a flame, and heated at 100-200℃ for 3-7 days. After cooling and filtration, the precipitate is collected, washed, and dried to obtain the quaternized covalent organic polymer.

[0007] Preferably, the molar ratio of 1,3,5-tris(4-formylphenyl)benzene and 4,4'-((2,5-di(hydrazinoyl)-1,4-phenyl)yl(oxy))di(N,N,N-trimethylbutyl)amine in S1 is 1:(1-2).

[0008] Preferably, the solvent in S1 comprises 1,4-dioxane, 1,3,5-trimethylbenzene and acetic acid, in a volume ratio of (1-5):(1-5):1; the concentration of the acetic acid is 6M.

[0009] The present invention also provides quaternized covalent organic polymers obtained by the above preparation method.

[0010] Another objective of this invention is to provide the application of the above-mentioned quaternized covalent organic polymers in the adsorption and separation of radioactive ions in nuclear wastewater or in the enrichment and recovery of rare and dispersed strategic metals.

[0011] As a preferred option, the radioactive ions in the adsorption and separation of nuclear wastewater are pertechnetate ions, and the enrichment and recovery of rare and dispersed strategic metals are achieved based on the adsorption and separation of perrhenate ions.

[0012] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention uses a one-step method to prepare the target covalent organic polymer. The process is simple and the reaction conditions are mild, which can meet the needs of laboratory research and large-scale production.

[0013] 2. This invention successfully introduces quaternary ammonium cationic functional groups into the covalent organic polymer backbone, which greatly enhances the material's ability to bind anions.

[0014] 3. This invention selects perrhenate, whose physicochemical properties are very similar to those of pertechnetate, as a model. The prepared quaternized covalent organic polymer has excellent adsorption performance for perrhenate and can directly provide a technical reference for the removal of radioactive pertechnetate from nuclear industrial wastewater, and has application potential in the field of nuclear pollution control.

[0015] 4. The quaternized covalent organic polymer of this invention can efficiently enrich perrhenate in water, and at the same time can realize the separation and recovery of rare strategic metal rhenium, effectively improving resource utilization and having both environmental benefits and economic value.

[0016] 5. The quaternized covalent organic polymer prepared by this invention has a stable backbone and can be adapted to complex water quality systems such as radioactive wastewater from the nuclear industry and smelting wastewater.

[0017] 6. The quaternized covalent organic polymer of this invention has strong versatility, and can be used for both radionuclide simulation and separation research and rare and dispersed strategic metal recovery, with a wide range of applications. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the preparation process of COP-TFPB-DHTBA.

[0019] Figure 2 PXRD spectra of TFPB, DHTBA, and COP-TFPB-DHTBA.

[0020] Figure 3 Infrared spectra of TFPB, DHTBA, and COP-TFPB-DHTBA.

[0021] Figure 4 The image shows the infrared spectra of COP-TFPB-DHTBA before and after adsorption of perrhenate.

[0022] Figure 5 XPS full spectrum of COP-TFPB-DHTBA before and after adsorption of perrhenate.

[0023] Figure 6 High-resolution XPS spectra of rhenium after adsorption of perrhenate in COP-TFPB-DHTBA. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with embodiments. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] Example 1: Preparation and Characterization of Quaternized Covalent Organic Polymers Weigh 1,3,5-tris(4-formylphenyl)benzene (16.8 mg, 0.043 mol) and 4,4'-((2,5-di(hydrazinoyl)-1,4-phenyl)yl(oxy))di(N,N,N-trimethylbutyl)amine (34.2 mg, 0.065 mol), and separately add 0.5 mL of 1,4-dioxane and 0.5 mL of 1,3,5-trimethylbenzene. Place all the contents into a Piezerx tube, sonicate for 10 minutes, and then add 0.1 mL of acetic acid solution (6 M) to obtain the reaction mixture. Degas the Piezerx tube containing the reaction mixture through three refrigeration pump-thawing cycles, then flame-seal and heat in an oven at 120°C for 3 days. After cooling, filter the mixture. Wash the resulting pale yellow solid product three times with N,N-dimethylformamide and tetrahydrofuran, and collect the solid. The quaternized covalent organic polymer (COP-TFPB-DHTBA) was obtained by vacuum drying at 80°C for 12 hours.

[0027] Figure 1 This is a schematic diagram of the preparation process of COP-TFPB-DHTBA.

[0028] Figure 2 These are the PXRD spectra of TFPB, DHTBA, and COP-TFPB-DHTBA. (Source: [Insert Source Here]) Figure 2 It is evident that both the raw material monomers TFPB and DHTBA exhibit multiple sharp and independent characteristic diffraction peaks, corresponding to the crystalline structures of the two monomers themselves; while the product COP-TFPB-DHTBA shows specific 2 θ At the angle, characteristic diffraction peaks distinct from those of the two raw materials appeared, and the characteristic peaks of the raw material monomers basically disappeared, proving that the monomers had fully participated in the reaction and the polymer was successfully synthesized.

[0029] Figure 3 These are the infrared spectra of TFPB, DHTBA, and COP-TFPB-DHTBA. (Source: [Insert Source Here]) Figure 3 As can be seen, the chemical structures of monomers TFPB, DHTBA, and the condensation product COP-TFPB-DHTBA were characterized by Fourier transform infrared spectroscopy. TFPB showed a wavelength range of approximately 1690-1700 cm⁻¹. -1 The aldehyde group exhibits a distinct C=O stretching vibration absorption peak at 3200-3500 cm⁻¹; DHTBA, on the other hand, shows an absorption peak at 3200-3500 cm⁻¹. -1 The region exhibits a distinct absorption band of the primary amine NH stretching vibration. After the condensation reaction, the characteristic C=O peak of the aldehyde group in TFPB in COP-TFPB-DHTBA is significantly weakened or almost disappears, while the NH absorption peak of the primary amine group in DHTBA is significantly reduced. More importantly, the absorption band of COP-TFPB-DHTBA at approximately 1640-1660 cm⁻¹... -1A new characteristic absorption peak appeared at approximately 1500-1600 cm⁻¹, which can be attributed to the stretching vibration of the C=N bond in the imine bond. This indicates that the aldehyde group of TFPB and the amino group of DHTBA underwent a Schiff base condensation reaction, forming an imine linkage structure. Furthermore, the COP-TFPB-DHTBA peak at approximately 1500-1600 cm⁻¹... -1 The absorption peaks of the C=C stretching vibration of the aromatic ring skeleton are still retained within the range, and characteristic absorptions related to the aromatic structure and CN bond are observed in the fingerprint region, indicating that the aromatic skeleton of the monomer is preserved during polymerization. The significant weakening of the characteristic peaks of the aldehyde and amino groups and the appearance of the newly formed C=N characteristic peak confirm that the imine bond was successfully constructed, and the covalent organic polymer COP-TFPB-DHTBA has been successfully synthesized.

[0030] Example 2: Efficient adsorption and separation of pertechnetate / perrhenate by quaternized covalent organic polymers Figure 4 These are the infrared spectra of COP-TFPB-DHTBA before and after adsorption of perrhenate. Figure 4 As can be seen, the overall profiles of the Fourier transform infrared spectra of COP-TFPB-DHTBA before and after adsorption of perrhenate are basically the same, and the material exhibits similar spectra at approximately 3400 cm⁻¹. -1 The nearby broad absorption band and 1600-1000 cm -1 The characteristic absorption peaks of the framework within the range were all retained, indicating that the adsorption process did not destroy the main chemical structure of COP-TFPB-DHTBA, demonstrating the material's good structural stability. Compared with before adsorption, COP-TFPB-DHTBA after adsorption of perrhenate showed a higher absorption peak at approximately 905 cm⁻¹. -1 A new absorption peak with significant enhancement appears at this point, which can be attributed to ReO4. - The characteristic stretching vibrations of the Re-O bond in the tetrahedral configuration indicate that perrhenate has been successfully adsorbed and immobilized in the COP-TFPB-DHTBA material.

[0031] Figure 5 These are the XPS full spectra of COP-TFPB-DHTBA before and after adsorption of perrhenate. Figure 5 As can be seen, after adsorbing perrhenate, COP-TFPB-DHTBA exhibited Re 4f and Re 4p peaks in the material. This is mainly attributed to the introduction of quaternary ammonium functional groups with strong affinity for pertechnetate / perrhenate into the material by COP-TFPB-DHTBA, which can construct highly efficient pertechnetate / perrhenate capturing nanochannels in the material, greatly improving the adsorption performance of the material for pertechnetate / perrhenate.

[0032] Figure 6 This is a high-resolution XPS spectrum of rhenium after adsorption of perrhenate using COP-TFPB-DHTBA. Figure 6 As can be seen, within the binding energy range of 40-52 eV, the spectrum exhibits a typical Re 4f spin-orbit splitting double peak, corresponding to Re 4f... 2 / 5 and Re4f 2 / 7 The peak spacing is approximately 2.3 eV, which is consistent with the standard binding energy characteristic of Re(VII) in perrhenate. This indicates that perrhenate has been successfully loaded onto the surface of the COP-TFPB-DHTBA material, and the valence state of rhenium did not change during the adsorption process, verifying the material's effective capture of perrhenate.

[0033] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they are not intended to limit the present invention. It should be noted that various changes and modifications can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the concept and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a quaternized covalent organic polymer, characterized in that, Includes the following steps: S1. Take 1,3,5-tris(4-formylphenyl)benzene and 4,4'-((2,5-di(hydrazinoyl)-1,4-phenyl)yl(oxy))di(N,N,N-trimethylbutyl)amine as the reaction raw materials, add solvent and sonicate to obtain a reaction mixture; S2. The container containing the reaction mixture is degassed by a freeze-thaw cycle, sealed with a flame, and heated at 100-200℃ for 3-7 days. After cooling and filtration, the precipitate is collected, washed, and dried to obtain the quaternized covalent organic polymer.

2. The method for preparing the quaternized covalent organic polymer according to claim 1, characterized in that, The molar ratio of 1,3,5-tris(4-formylphenyl)benzene and 4,4'-((2,5-di(hydrazinoyl)-1,4-phenyl)yl(oxy))di(N,N,N-trimethylbutyl)amine in S1 is 1:(1-2).

3. The method for preparing the quaternized covalent organic polymer according to claim 1, characterized in that, The solvent in S1 includes 1,4-dioxane, 1,3,5-trimethylbenzene and acetic acid, with a volume ratio of (1-5):(1-5):1; the concentration of the acetic acid is 6M.

4. The quaternized covalent organic polymer obtained by the preparation method according to any one of claims 1-3.

5. The application of the quaternized covalent organic polymer as described in claim 4 in the adsorption and separation of radioactive ions in nuclear wastewater or the enrichment and recovery of rare and dispersed strategic metals.

6. The application according to claim 5, characterized in that, The radioactive ions in the nuclear wastewater separated by adsorption are pertechnetate ions, and the enrichment and recovery of rare and dispersed strategic metals are achieved based on the adsorption and separation of perrhenate ions.

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