Method for large-scale preparation of crystalline carboxyl-functionalized covalent triazine framework through Friedel-Crafts reaction

Abstract

The invention discloses a method for large-scale preparation of a crystalline carboxyl-functionalized covalent triazine framework through a Friedel-Crafts reaction. The method comprises the following steps: grinding and mixing a triazine-containing monomer and a carboxyl-containing monomer, adding into a quartz tube filled with a catalyst, freezing the reaction mixture with liquid nitrogen, sealing the quartz tube in a vacuum state, heating and reacting for a period of time to obtain a reaction head product, grinding the reaction head product, and washing to obtain the triazine-containing monomer. And drying in vacuum to obtain crystalline carboxyl-functionalized CTFs powder. The preparation method is simple to operate and low in raw material cost, large-scale preparation can be performed, and the prepared CTFs have the characteristics of high crystallinity, carboxyl functionalization, rich nitrogen content and the like, have excellent mixed matrix membrane processing performance and antibiotic adsorption performance, and have a relatively great application prospect in the fields of adsorption and separation.

Description

Technical Field

[0001] The present invention relates to a method for preparing a covalent triazine framework, in particular to a method for preparing a crystallized, carboxyl-functionalized covalent triazine framework on a large scale through a Friedel-Crafts reaction, and its application in mixed matrix membrane processing and antibiotic adsorption. Background Art

[0002] Covalent triazine frameworks (CTFs) are porous organic polymers covalently linked by triazine units. Due to their good chemical and thermal stability, rich nitrogen content, high porosity and high specific surface area, they have attracted extensive attention in recent years and have been used in adsorption and separation, energy storage and conversion, and photo / electric / thermal catalysis. However, most of the CTFs reported so far are amorphous or semi-crystalline, and the synthesis of crystalline CTFs is limited to a few building blocks. Highly crystalline CTFs that can be directly functionalized have not yet been seen. Therefore, it is crucial to develop a new method for synthesizing crystalline and functionalized CTFs.

[0003] At present, there are three main methods for preparing CTFs: (1) cyano trimerization strategy, (2) imidazole salt condensation strategy, and (3) Friedel-Crafts reaction strategy. Among them, the cyano trimerization strategy has a rich variety of catalysts, mainly high-temperature catalysts, including zinc chloride (ZnCl2), phosphorus pentoxide (P2O5) and polyphosphoric acid, and the CTFs obtained are mainly black products; the lower temperature catalyst is trifluoromethanesulfonic acid (CF3SO3H), which can obtain light-colored CTFs samples with excellent photoelectric properties and can be effectively used in applications such as photocatalysis. The imidazole salt condensation strategy has a lower reaction temperature, and the reaction can be carried out in an open system. The obtained CTFs are usually uncarbonized products, which can be effectively used in fields such as photocatalysis. However, the excessive reaction time and excessive use of organic solvents have greatly limited the industrial production and application of the amidine salt condensation strategy.

[0004] Friedel-Crafts reaction has the advantages of simple reaction operation and rich building blocks, which can effectively expand the types of CTFs and carry out industrial preparation at low cost. However, the low reversibility and large number of reactive sites make the synthesis of crystalline CTFs by Friedel-Crafts reaction a very challenging problem, limiting its application in crystalline porous materials. Summary of the invention

[0005] In order to solve the problems existing in the background technology, the purpose of the present invention is to provide a method for large-scale preparation of crystalline, carboxyl-functionalized covalent triazine frameworks by Friedel-Crafts reaction, using a catalyst with high catalytic activity to catalyze the Friedel-Crafts reaction of triazine monomers and carboxyl-functionalized monomers to synthesize CTFs with crystallinity and carboxyl functionalization.

[0006] The present invention is simple to operate, has low raw material cost, and can be prepared on a large scale. At the same time, the prepared CTFs have the characteristics of high crystallinity, carboxyl functionalization, and rich nitrogen content. It has excellent mixed matrix membrane processing performance and antibiotic adsorption performance, and can achieve the preparation of kilogram-level CTFs. It has great application prospects in the field of adsorption and separation.

[0007] The technical solution adopted by the present invention is:

[0008] 1. A method for the large-scale preparation of crystalline, carboxyl-functionalized covalent triazine frameworks via Friedel-Crafts reaction:

[0009] (1) grinding and mixing a certain amount of triazine-containing monomer a and carboxyl-containing monomer b, adding the mixture into a quartz tube containing a certain amount of catalyst c and sealing the tube;

[0010] (2) transferring the quartz tube obtained in the above (1) to a muffle furnace, heating and reacting at a certain temperature for a period of time to obtain a preliminary reaction product;

[0011] (3) The initial reaction product obtained in the above (2) is ground, solvent washed and vacuum dried to obtain a crystalline CTFs powder as a crystalline, carboxyl functionalized covalent triazine framework.

[0012] In the step (1), the triazine-containing monomer a used is 2,4,6-trichloro-1,3,5-triazine, the carboxyl-containing monomer b used is one of 1,4-phthalic acid and 1,3,5-benzenetricarboxylic acid, and in the step (1), the catalyst c used is one of common Friedel-Crafts reaction catalysts such as trifluoromethanesulfonic acid (CF3SO3H), ferric chloride (FeCl3), and aluminum chloride (AlCl3).

[0013] In the step (1), the amount of the triazine-containing monomer a, the carboxyl-containing monomer b and the catalyst c used is in the following relationship: 10 mg-200 mg: 10-200 mg: 10 uL-200 uL.

[0014] In the step (1), after the catalyst is added, the quartz tube is frozen with liquid nitrogen and then flame-sealed under vacuum.

[0015] In the step (2), the heating temperature used is 200-350° C. and the heating time is 0.5-12 h.

[0016] In the step (2), the muffle furnace heating and heat preservation program is set to heat up to 250° C. at a heating rate of 5° C. / min and then keep the temperature for 30 minutes.

[0017] In the step (3), during the solvent washing process, the washing solvent is one or more of deionized water, anhydrous ethanol, N,N-dimethylformamide, acetone, and tetrahydrofuran.

[0018] In the step (3), the product is vacuum dried at a temperature of 80-150° C. and a drying time of 6-12 h.

[0019] 2. An application of a crystalline, carboxyl-functionalized covalent triazine framework prepared on a large scale by Friedel-Crafts reaction in the preparation of mixed matrix membranes and the adsorption of antibiotics for the preparation of antibiotic adsorbents. The application specifically includes the use of the covalent triazine framework as a filler to prepare mixed matrix membranes and the use of the covalent triazine framework as an adsorbent for antibiotic adsorption.

[0020] The mixed matrix membrane generally refers to a polymer-based mixed matrix membrane, and the antibiotic generally refers to a quinolone antibiotic.

[0021] The invention adopts a Friedel-Crafts reaction strategy with electron-withdrawing group effect and steric hindrance effect to prepare CTFs with crystallinity and carboxyl functionalization.

[0022] The present invention uses a catalyst with high catalytic activity to obtain highly crystalline CTFs in a short time (30 minutes). At the same time, due to the low cost of the reaction raw materials, kilogram-level high-crystalline samples can be prepared. The prepared kilogram-level samples can be effectively used for the processing of mixed matrix membranes after ball milling and pulverization. The bulk CTFs material can be used for antibiotic adsorption, showing good application prospects.

[0023] The beneficial effects of the present invention are:

[0024] The purpose of the present invention is to provide a method technology for large-scale preparation of crystalline, carboxyl-functionalized covalent triazine frameworks through Friedel-Crafts reaction, introducing a Friedel-Crafts reaction mode with electron-withdrawing group effect and steric hindrance effect to synthesize crystalline, carboxyl-functionalized CTFs.

[0025] The invention has simple operation process, cheap and readily available raw materials, can be further prepared on a large scale, and is a method with industrial application prospects.

[0026] The present invention can effectively expand the building blocks with two different pores (1,4-benzenedicarboxylic acid and 1,3,5-benzenetricarboxylic acid), have rich nitrogen content and carboxyl content, and have excellent antibiotic adsorption performance. At the same time, the hydrophilic nature of the carboxyl group can effectively assist in the nanoparticleization of CTFs for the processing of mixed matrix membranes. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The molecular structures and powder XRD patterns of the two prepared carboxyl functionalized CTFs are shown, wherein Figure a shows the powder XRD data of the synthesized product CTF-2COOH, and the embedded figure shows the molecular structure of CTF-2COOH; Figure b shows the powder XRD data of the synthesized product CTF-3COOH, and the embedded figure shows the molecular structure of CTF-3COOH;

[0028] Figure 2 FTIR graphs showing the two prepared carboxyl functionalized CTFs;

[0029] Figure 3 The XPS and NMR images of the two prepared carboxyl functionalized CTFs are shown, wherein Figure a shows the XPS O1S and C1S spectra of CTF-2COOH and CTF-3COOH, and Figure b shows the solid NMR C spectra of CTF-2COOH and CTF-3COOH;

[0030] Figure 4 The nitrogen adsorption-desorption isotherms and pore size distribution diagrams of the two prepared carboxyl functionalized CTFs are shown, wherein Figure a shows the nitrogen adsorption-desorption curve of the synthesized product CTF-2COOH, and the inset diagram shows its pore size distribution curve, and Figure b shows the nitrogen adsorption-desorption curve of the synthesized product CTF-3COOH, and the inset diagram shows its pore size distribution curve;

[0031] Figure 5 The SEM, AFM and TEM morphologies of the two prepared carboxyl functionalized CTFs are shown, wherein Figure a shows the SEM image of CTF-2COOH, Figure b shows the SEM image of CTF-3COOH, Figure c shows the AFM image of CTF-2COOH, Figure d shows the AFM image of CTF-3COOH, Figure e shows the TEM image of CTF-2COOH, and Figure f shows the TEM image of CTF-3COOH;

[0032] Figure 6 The graphs represent the antibiotic (ofloxacin, OFX) adsorption performance of the prepared carboxyl functionalized CTF-2COOH samples, wherein Figure a represents the OFX adsorption kinetic curves of CTF-1 and CTF-2COOH, and Figure b represents the OFX adsorption isotherms of CTF-1 and CTF-2COOH.

[0033] Figure 7 Optical photographs, PXRD data, FTIR data, nitrogen adsorption-desorption isotherms and pore size distribution diagrams of carboxyl functionalized CTFs prepared on a large scale are shown, wherein Figure a shows an optical photograph of CTF prepared on a large scale, Figure b shows PXRD data of CTF prepared on a large scale, Figure c shows FTIR diagram of CTF prepared on a large scale, Figure d shows nitrogen adsorption-desorption isotherms of CTF prepared on a large scale, and the inset shows its pore size distribution curve;

[0034] Figure 8 The processing diagram of the mixed matrix membrane of carboxyl functionalized CTFs prepared on a large scale and the PXRD patterns of the mixed matrix membranes with different CTFs loading amounts are shown, wherein Figure a shows an optical photograph of the mixed matrix membrane with a CTF content of 0-60wt%, Figure b shows an optical photograph of the mixed matrix membrane with an A4 paper size, and Figure c shows PXRD data of the mixed matrix membrane with a CTF content of 0-60wt%;

[0035] Fig. 9 The PXRD and nitrogen adsorption-desorption isotherms of the prepared CTF-1 comparative sample are shown, wherein Figure a shows the PXRD diagram of CTF-1, Figure b shows the nitrogen adsorption-desorption isotherm of CTF-1, and the embedded figure shows its pore size distribution curve. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with the accompanying drawings and the following embodiments. It should be understood that the accompanying drawings and the following embodiments are only used to illustrate the present invention, rather than to limit the present invention.

[0037] Embodiments of the present invention are as follows:

[0038] Example 1

[0039] First, the monomer 2,4,6-trichloro-1,3,5-triazine (TCT) (100 mg) and the monomer 1,4-phthalic acid (PTA) (100 mg) were ground and mixed, and added to a 10mL quartz heat-resistant tube containing the catalyst CF3SO3H (50uL). After cooling in liquid nitrogen for 5 minutes, the sealed quartz tube was melted by flame and transferred to a muffle furnace. The muffle furnace insulation program was set to 200°C for 30 minutes (heating rate 5°C / min). After the reaction was completed, the quartz tube was cooled with liquid nitrogen for 5 minutes and the initial reaction product was collected by grinding. It was washed in turn with deionized water, anhydrous ethanol, N,N-dimethylformamide, acetone and tetrahydrofuran, and vacuum dried at 120°C for 12 hours to obtain the crystalline product CTF-2COOH. The PXRD data of CTF-2COOH are shown in Figure 1 As shown in (a), CTF-2COOH has good crystallinity, and the embedded figure is the molecular structure of CTF-2COOH. Figure 2As shown in the FTIR test of CTF-2COOH, the wavelength range of 2500-3200 cm -1 With 1716cm -1 The characteristic peak of carboxyl group, Figure 3 The XPS test of CTF-2COOH in (a) also observed the peak of carboxyl group. Figure 3 The solid-state NMR of CTF-2COOH in (b) also observed the presence of carboxyl groups C, indicating that the carboxyl groups are retained on the CTF skeleton. Figure 4 As shown in (a), the nitrogen adsorption-desorption isotherm of CTF-2COOH shows that the specific surface area of ​​CTF-2COOH is 653 m 2 g -1 , and the pore size distribution is mainly concentrated at 0.95nm, which proves the formation of ordered pores in CTF-2COOH. The morphological characterization of CTF-2COOH shows its microscopic morphology, such as Figure 5 As shown in (a), SEM test shows that CTF-2COOH has a certain layered structure, so further simple peeling treatment can obtain nanosheets. The specific characterization is as follows Figure 5 As shown in (c), the obtained nanosheets are 3-4 nm in size, and the TEM characterization also observed the product with nanosheet morphology, such as Figure 5 (e) As shown. The obtained CTF-2COOH can be used for the adsorption treatment of antibiotic ofloxacin (OFX), such as Figure 6 As shown in (a), the antibiotic adsorption kinetic curve shows that the antibiotic adsorption rate of CTF-2COOH is significantly better than that of the unfunctionalized CTF-1 sample. Figure 6 (b) From the antibiotic adsorption isotherm, it can be seen that CTF-2COOH also has a better maximum antibiotic adsorption performance than CTF-1, which proves the effective effect of CTF carboxyl functionalization.

[0040] Example 2

[0041] First, the monomer 2,4,6-trichloro-1,3,5-triazine (TCT) (100 mg) and the monomer 1,4-phthalic acid (PTA) (100 mg) were ground and mixed, added to a 10 mL quartz heat-resistant tube containing a catalyst CF3SO3H (50 uL), cooled in liquid nitrogen for 5 min, flame-melted and sealed quartz tube, and then transferred to a muffle furnace. The muffle furnace insulation program was set to 200 ° C for 60 min (heating rate 5 ° C / min). After the reaction was completed, the quartz tube was cooled with liquid nitrogen for 5 min and the initial reaction product was collected by grinding. It was washed with deionized water, anhydrous ethanol, N, N-dimethylformamide, acetone and tetrahydrofuran in turn, and vacuum dried at 120 ° C for 12 h to obtain the crystalline product CTF-2COOH.

[0042] Example 3

[0043] First, the monomer 2,4,6-trichloro-1,3,5-triazine (TCT) (100 mg) and the monomer 1,4-phthalic acid (PTA) (100 mg) were ground and mixed, added to a 10 mL quartz heat-resistant tube containing a catalyst CF3SO3H (50 uL), cooled in liquid nitrogen for 5 min, flame-melted and sealed quartz tube, and then transferred to a muffle furnace. The muffle furnace insulation program was set to 200 ° C for 120 min (heating rate 5 ° C / min). After the reaction was completed, the quartz tube was cooled with liquid nitrogen for 5 min and the initial reaction product was collected by grinding. It was washed with deionized water, anhydrous ethanol, N, N-dimethylformamide, acetone and tetrahydrofuran in turn, and vacuum dried at 120 ° C for 12 h to obtain the crystalline product CTF-2COOH.

[0044] Example 4

[0045] First, the monomer 2,4,6-trichloro-1,3,5-triazine (TCT) (100 mg) and the monomer 1,4-phthalic acid (PTA) (100 mg) were ground and mixed, added to a 10 mL quartz heat-resistant tube containing a catalyst CF3SO3H (50 uL), cooled in liquid nitrogen for 5 min, flame-melted and sealed quartz tube, and then transferred to a muffle furnace. The muffle furnace insulation program was set to 200 ° C for 12 h (heating rate 5 ° C / min). After the reaction was completed, the quartz tube was cooled with liquid nitrogen for 5 min and the initial reaction product was collected by grinding. It was washed with deionized water, anhydrous ethanol, N, N-dimethylformamide, acetone and tetrahydrofuran in turn, and vacuum dried at 120 ° C for 12 h to obtain the crystalline product CTF-2COOH.

[0046] Example 5

[0047] First, the monomer 2,4,6-trichloro-1,3,5-triazine (TCT) (200g) and the monomer 1,4-phthalic acid (PTA) (300g) were ground and mixed, added to a 2L quartz heat-resistant tube containing a catalyst CF3SO3H (100mL), cooled in liquid nitrogen for 5min, flame-melted and sealed quartz tube, and then transferred to a muffle furnace. The muffle furnace insulation program was set to 200℃ for 12h (heating rate 5℃ / min). After the reaction was completed, the quartz tube was cooled with liquid nitrogen for 5min and the initial reaction product was collected by grinding. Deionized water, anhydrous ethanol, N,N-dimethylformamide, acetone and tetrahydrofuran were used to wash in turn, and the large-scale crystalline product CTF-2COOH was obtained after vacuum drying at 120℃ for 12h.

[0048] like Figure 7 (a) is an optical photograph of a large-scale prepared sample, such as Figure 7 As shown in (b), it can be seen that the sample prepared on a large scale has good crystallinity. Figure 7 As shown in (c), the FTIR data of the large-scale prepared sample also observed the characteristic absorption peak of the carboxyl group, indicating that the carboxyl group was successfully retained on the CTF skeleton. Figure 7 As shown in (d), it can be seen that the sample prepared on a large scale has a higher specific surface area. Its nitrogen adsorption-desorption isotherm shows that the large-scale sample has a surface area of ​​760 m 2 g -1 The specific surface area of ​​​​the nanostructured CTF was 0.99 nm, and the pore size distribution curve showed that its pore size was mainly concentrated at 0.99 nm. The CTF prepared on a large scale was ball-milled for 1 hour to obtain nanoparticles of CTF, which can be further used in the processing of mixed matrix membranes. In view of the good hydrophilicity of carboxyl functionalized CTF, polyvinyl alcohol (PVA) was selected as the polymer substrate for the processing of CTF mixed matrix membranes. Figure 8 As shown in (a), mixed matrix membranes with different CTF contents ranging from 0 wt% to 60 wt% can be prepared, demonstrating the high miscibility of carboxylated CTF and the polymer substrate PVA. At the same time, since CTF can be prepared on a large scale, large-sized CTF mixed matrix membranes can be further prepared, such as Figure 8 As shown in (b), a CTF mixed matrix membrane with a size of about A4 paper can be prepared. Figure 8 (c) PXRD data of the mixed matrix membrane shows that with the increase of CTF loading, the mixed matrix membrane exhibits an enhanced PXRD signal peak, which further proves the successful loading of CTF.

[0049] Example 6

[0050] First, the monomer 2,4,6-trichloro-1,3,5-triazine (TCT) (100 mg) and the monomer 1,3,5-benzenetricarboxylic acid (TMA) (100 mg) were ground and mixed, added to a 10 mL quartz heat-resistant tube containing a catalyst CF3SO3H (50 uL), cooled in liquid nitrogen for 5 min, flame-melted and sealed quartz tube, and then transferred to a muffle furnace. The muffle furnace insulation program was set to 200 ° C for 60 min (heating rate 5 ° C / min). After the reaction was completed, the quartz tube was cooled with liquid nitrogen for 5 min and the initial reaction product was collected by grinding. It was washed with deionized water, anhydrous ethanol, N, N-dimethylformamide, acetone and tetrahydrofuran in turn, and dried in vacuum at 120 ° C for 12 h to obtain the crystalline product CTF-3COOH.

[0051] The PXRD data of CTF-3COOH are as follows Figure 1 As shown in (b), CTF-3COOH has good crystallinity, and the embedded figure is the molecular structure of CTF-3COOH. Figure 2 As shown in the FTIR test of CTF-3COOH, the wavelength range of 2500-3200 cm -1With 1716cm -1 The characteristic peak of carboxyl group, Figure 3 The XPS test of CTF-3COOH in (a) also observed the peak of carboxyl group. Figure 3 The solid-state NMR of CTF-3COOH in (b) also observed the presence of carboxyl groups C, indicating that the carboxyl groups are retained on the CTF skeleton. Figure 4 (b) shows the nitrogen adsorption-desorption isotherm of CTF-3COOH. The test shows that the specific surface area of ​​CTF-3COOH is 7.16 m 2 g -1 The morphological characterization of CTF-3COOH shows its microscopic morphology, such as Figure 5 As shown in (b), SEM test shows that CTF-3COOH has a certain layered structure, so further simple peeling treatment can obtain nanosheets. The specific characterization is as follows Figure 5 As shown in (d), the obtained nanosheets are 3-4 nm in size, and the TEM characterization also observed the product with nanosheet morphology, such as Figure 5 (f) as shown.

[0052] Example 7

[0053] First, the monomer 2,4,6-trichloro-1,3,5-triazine (TCT) (100 mg) and the monomer 1,3,5-benzenetricarboxylic acid (TMA) (100 mg) were ground and mixed, added to a 10 mL quartz heat-resistant tube containing a catalyst CF3SO3H (100 uL), cooled in liquid nitrogen for 5 min, flame-melted and sealed quartz tube, and then transferred to a muffle furnace. The muffle furnace insulation program was set to 200 ° C for 60 min (heating rate 5 ° C / min). After the reaction was completed, the quartz tube was cooled with liquid nitrogen for 5 min and the initial reaction product was collected by grinding. It was washed with deionized water, anhydrous ethanol, N, N-dimethylformamide, acetone and tetrahydrofuran in turn, and dried in vacuum at 120 ° C for 12 h to obtain the crystalline product CTF-3COOH.

[0054] Example 8

[0055] First, the monomer 2,4,6-trichloro-1,3,5-triazine (TCT) (100 mg) and the monomer 1,3,5-benzenetricarboxylic acid (TMA) (100 mg) were ground and mixed, added to a 10 mL quartz heat-resistant tube containing a catalyst CF3SO3H (100 uL), cooled in liquid nitrogen for 5 min, flame-melted and sealed quartz tube, and then transferred to a muffle furnace. The muffle furnace insulation program was set to 200 ° C for 12 h (heating rate 5 ° C / min). After the reaction was completed, the quartz tube was cooled with liquid nitrogen for 5 min and the initial reaction product was collected by grinding. It was washed with deionized water, anhydrous ethanol, N, N-dimethylformamide, acetone and tetrahydrofuran in turn, and dried in vacuum at 120 ° C for 12 h to obtain the crystalline product CTF-3COOH.

[0056] Example 9

[0057] First, the monomer 2,4,6-trichloro-1,3,5-triazine (TCT) (50 mg) and the monomer 1,3,5-benzenetricarboxylic acid (TMA) (50 mg) were ground and mixed, added to a 10 mL quartz heat-resistant tube containing a catalyst CF3SO3H (50 uL), cooled in liquid nitrogen for 5 min, flame-melted and sealed quartz tube, and then transferred to a muffle furnace. The muffle furnace insulation program was set to 300 ° C for 12 h (heating rate 5 ° C / min). After the reaction was completed, the quartz tube was cooled with liquid nitrogen for 5 min and the initial reaction product was collected by grinding. It was washed with deionized water, anhydrous ethanol, N, N-dimethylformamide, acetone and tetrahydrofuran in turn, and dried in vacuum at 120 ° C for 12 h to obtain the crystalline product CTF-3COOH.

[0058] Comparative Example 1

[0059] First, the monomer 1,4-benzenedicarbonitrile (DCB) (200 mg) and the catalyst CF3SO3H (100 uL) were added to a 10 mL quartz heat-resistant tube, cooled in liquid nitrogen for 5 min, and then the sealed quartz tube was melted by flame and transferred to a muffle furnace. The muffle furnace was set to keep warm at 250 ° C for 12 h (heating rate 5 ° C / min). After the reaction was completed, the quartz tube was cooled with liquid nitrogen for 5 min and the initial reaction product was collected by grinding. It was washed with deionized water, anhydrous ethanol, N, N-dimethylformamide, acetone and tetrahydrofuran in turn, and dried in vacuum at 120 ° C for 12 h to obtain the crystalline product CTF-1.

[0060] like Fig. 9 As shown in (a), the PXRD test of comparative example CTF-1 shows its good crystallinity. Fig. 9 As shown in (b), the nitrogen adsorption-desorption isotherm test of CTF-1 shows that the specific surface area of ​​CTF-1 is 763 m 2 g -1, the pore size distribution is mainly concentrated at 1.1 nm, proving the successful synthesis of comparative example CTF-1.

[0061] Comparative Example 2

[0062] First, the monomer 1,4-benzenedicarbonitrile (DCB) (100 mg) and the catalyst CF3SO3H (50 uL) were added to a 10 mL quartz heat-resistant tube, cooled in liquid nitrogen for 5 min, flame-melted and sealed, and then transferred to a muffle furnace. The muffle furnace insulation program was set to 250 ° C for 12 h (heating rate 5 ° C / min). After the reaction was completed, the quartz tube was cooled with liquid nitrogen for 5 min and the initial reaction product was collected by grinding. It was washed with deionized water, anhydrous ethanol, N, N-dimethylformamide, acetone and tetrahydrofuran in turn, and vacuum dried at 120 ° C for 12 h to obtain the crystalline product CTF-1.

[0063] Comparative Example 3

[0064] First, the monomer 1,4-benzenedicarbonitrile (DCB) (100 mg) and the catalyst CF3SO3H (200 uL) were added to a 10 mL quartz heat-resistant tube, which was then cooled in liquid nitrogen for 10 min and melted and sealed. After the sealed tube returned to room temperature, it was transferred to a household microwave oven, and the reaction power was controlled to 800 W. After reacting for 20 min, the product was washed with ammonia water, anhydrous ethanol, acetone and tetrahydrofuran in turn, and dried in vacuum at 120 ° C to obtain the crystalline product CTF-1.

[0065] In summary, the present invention can achieve crystallization and preparation of carboxyl-functionalized covalent triazine frameworks through Friedel-Crafts reaction, and can also achieve kilogram-level CTF preparation. The prepared CTF can be effectively used for the adsorption treatment of the antibiotic ofloxacin, and has excellent antibiotic removal efficiency. After a simple ball milling treatment, the large-scale prepared CTF can be used for the processing of mixed matrix membranes, and a high CTF loading and large-size mixed matrix membrane can be prepared. It can be seen that carboxyl-functionalized CTF has great application prospects in the field of antibiotic adsorption and mixed matrix membrane processing.

Claims

1. A method for preparing a crystalline, carboxyl-functionalized covalent triazine framework on a large scale by Friedel-Crafts reaction, characterized in that: the method steps are as follows: (1) grinding and mixing a certain amount of triazine-containing monomer a and carboxyl-containing monomer b, adding the mixture into a quartz tube containing a certain amount of catalyst c and sealing the tube; (2) transferring the quartz tube obtained in the above (1) to a muffle furnace, heating and reacting at a certain temperature for a period of time to obtain a preliminary reaction product; (3) The initial reaction product obtained in the above (2) is ground, solvent washed and vacuum dried to obtain a crystalline CTFs powder as a crystalline, carboxyl functionalized covalent triazine framework.

2. A method for preparing a crystalline, carboxyl-functionalized covalent triazine framework on a large scale by Friedel-Crafts reaction according to claim 1, characterized in that: In the step (1), the triazine-containing monomer a used is 2,4,6-trichloro-1,3,5-triazine, the carboxyl-containing monomer b used is one of 1,4-phthalic acid and 1,3,5-benzenetricarboxylic acid, and in the step (1), the catalyst c used is one of common Friedel-Crafts reaction catalysts such as trifluoromethanesulfonic acid (CF3SO3H), ferric chloride (FeCl3), and aluminum chloride (AlCl3).

3. A method for large-scale preparation of a crystalline, carboxyl-functionalized covalent triazine framework by Friedel-Crafts reaction according to claim 1 or 2, characterized in that: In the step (1), the amount of the triazine-containing monomer a, the carboxyl-containing monomer b and the catalyst c used is in the following relationship: 10 mg-200 mg: 10-200 mg: 10 uL-200 uL.

4. A method for large-scale preparation of a crystalline, carboxyl-functionalized covalent triazine framework by Friedel-Crafts reaction according to claim 1, characterized in that: In the step (1), the quartz tube is flame-sealed under vacuum after being frozen with liquid nitrogen.

5. A method for large-scale preparation of a crystalline, carboxyl-functionalized covalent triazine framework by Friedel-Crafts reaction according to claim 1, characterized in that: In the step (2), the heating temperature used is 200-350° C. and the heating time is 0.5-12 h.

6. A method for large-scale preparation of a crystalline, carboxyl-functionalized covalent triazine framework by Friedel-Crafts reaction according to claim 1, characterized in that: In the step (2), the muffle furnace heating and insulation program is set to heat up to 200-350° C. at a heating rate of 5° C. / min, and then keep the temperature for 0.5-12 h.

7. A method for large-scale preparation of a crystalline, carboxyl-functionalized covalent triazine framework by Friedel-Crafts reaction according to claim 1, characterized in that: In the step (3), during the solvent washing process, the washing solvent is one or more of deionized water, anhydrous ethanol, N,N-dimethylformamide, acetone, and tetrahydrofuran.

8. A method for large-scale preparation of a crystalline, carboxyl-functionalized covalent triazine framework by Friedel-Crafts reaction according to claim 1, characterized in that: In the step (3), the product is vacuum dried at a temperature of 80-150° C. and a drying time of 6-12 h.

9. A crystalline, carboxyl-functionalized covalent triazine framework prepared on a large scale by Friedel-Crafts reaction, characterized in that: The covalent triazine framework is prepared by the method described in any one of claims 1-8.

10. The use of the covalent triazine framework according to claim 9, characterized in that: Application in preparation of mixed matrix membranes and adsorption of antibiotics.

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