Preparation method of azo cofs and application in adsorption of organic dyes

Abstract

The application relates to the technical field of material chemistry, and discloses a preparation method of a COF material containing an azo group, raw materials of which include aminoazobenzene monomers and aldehyde pyrene monomers, and auxiliary materials of which include organic solvents and a catalyst; the preparation steps include uniformly mixing the aminoazobenzene monomers, the aldehyde pyrene monomers and the organic solvents, then adding the catalyst to perform freezing, degassing and sealing, standing at 120-150 DEG C for 7-11 days, washing and drying the obtained precipitate, and obtaining the COF material containing the azo group. The azo TFPPY-AZO COF is synthesized by using a one-step method, the preparation method is simple, the structure is stable, the environment is friendly, the azo TFPPY-AZO COF can be directly used for adsorption and removal of a Congo red dye in an aqueous solution without complex post-treatment, the prepared azo TFPPY-AZO COF has a mesoporous structure and a large specific surface area, the structure is stable, the mesoporous structure and rich action sites greatly improve the adsorption rate of the TFPPY-AZO COF on the Congo red dye, and good adsorption of the Congo red dye in the aqueous solution is realized.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of material chemistry, in particular to a preparation method of azo COFs materials and application of the azo COFs materials in adsorption of organic dyes. BACKGROUND

[0002] Organic dyes are widely used in plastic, printing, paint, cosmetics, textile, paper and other manufacturing industries and daily life, however, with the rapid development of the dye industry, failure to remove dyes from these waste sources may cause serious harm to aquatic environments and human health. Therefore, exploring an efficient and simple method for adsorption and removal of organic dyes is of great significance to the physical and mental health of human beings and environmental protection. At present, most traditional methods have been used to eliminate organic pollutants in contaminated water, including photocatalytic method, advanced oxidation method, membrane separation method, electrochemical method and the like, but due to the shortcomings of expensive instruments, long process time, easy generation of toxic by-products in the removal process and the like, the practical application of the methods is hindered. The adsorption method has important prospects in dye elimination due to its advantages of high efficiency, simple operation, low cost and negligible generation of toxic by-products. So far, a variety of porous materials have been developed for use as adsorbents, such as porous organic polymers (POPs), porous aromatic frameworks (PAFs) and metal-organic frameworks (MOFs), but the lower specific surface area and poor stability of the frameworks make them not conducive to the adsorption and removal of organic dyes.

[0003] Therefore, it is an urgent problem for those skilled in the art to provide a porous adsorption material with large specific surface area and high stability and a preparation method thereof. The present application provides a preparation method of azo COFs for adsorption of organic dyes. SUMMARY

[0004] (I) Technical problems solved

[0005] In view of the deficiencies in the prior art, the present application provides a preparation method of azo COFs, which has the advantages of large pore size, large specific surface area and rich active sites, so that the azo COFs can perform super-fast adsorption and efficient removal of Congo red dyes, and has good application potential.

[0006] (II) Technical solutions

[0007] To achieve the above object, the present application provides the following technical solutions: a preparation method of azo COFs, raw materials comprising aminoazobenzene monomers and aldehyde pyrene monomers, and auxiliary materials comprising organic solvents and catalysts.

[0008] The preparation steps are as follows:

[0009] S101, mixing the aminoazobenzene monomer, the aldehyde pyrene monomer and the organic solvent uniformly, then adding a catalyst to freeze, degas and seal;

[0010] S102, then standing at 120-150 DEG C for 7-11 days;

[0011] S103, finally washing and drying the obtained precipitate to obtain an azo COFs material.

[0012] Preferably, the aminoazobenzene monomer is p-diaminoazobenzene, and the aldehyde pyrene monomer is 1,3,6,8-tetra (4-formylphenyl) pyrene.

[0013] Preferably, the molar ratio of the aldehyde pyrene monomer to the aminoazobenzene monomer is 1:2.

[0014] Preferably, the organic solvent is added in an amount to make the concentration of the aldehyde pyrene monomer 0.075-0.15 mmol / mL.

[0015] Preferably, the organic solvent is a mixture of o-dichlorobenzene / n-butanol or mesitylene / dioxane in a volume ratio of 1:1.

[0016] Preferably, the catalyst is acetic acid, and the concentration of the acetic acid is 6 mol / L.

[0017] Preferably, the molar ratio of the aldehyde pyrene monomer to the catalyst is 1:30-40.

[0018] Preferably, the azo COFs material is used for adsorbing and removing Congo red dye, the COFs material is added to a solution containing different concentrations of Congo red dye, and then filtered after shaking for 24 h.

[0019] Preferably, the concentration of the Congo red dye ranges from 10 ppm to 100 ppm.

[0020] Preferably, the COFs material is added to a 75 ppm Congo red dye solution, and then filtered after stirring for different times.

[0021] Preferably, the different times range from 0 min to 240 min.

[0022] Preferably, the pore size of the filter membrane is 0.22 microns.

[0023] Compared with the prior art, the present application provides a preparation method of azo COFs, which has the following beneficial effects:

[0024] 1. The azo COFs material preparation method, the present application adopts one-step method to synthesize TFPPY-AZOCOF containing azo group, the preparation method is simple, the structure is stable, the environment is friendly, and the azo COFs material can be directly used for adsorption and removal of congo red dye in aqueous solution without complex post-treatment.

[0025] 2. The azo COFs material preparation method, the azo TFPPY-AZO COF prepared by the method of the present application has mesoporous structure and large specific surface area, and there are various interactions such as π-π stacking and hydrogen bonding between the azo TFPPY-AZO COF and congo red dye. In addition to the stability of the structure, the mesoporous structure also greatly improves the adsorption rate of the TFPPY-AZO COF for congo red dye, and the TFPPY-AZO COF can realize good adsorption effect for congo red dye in aqueous solution.

[0026] 3. The azo COFs material preparation method, the azo TFPPY-AZO COF prepared by the method of the present application realizes rapid and high-capacity adsorption of congo red dye in aqueous solution, is a high-efficiency adsorbent and remover for congo red dye, and has good application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The PXRD graph of the TFPPY-AZO COF of the present application embodiment 1, wherein the thick curve is the experimental PXRD data, and the thin curve is the PXRD result of the simulated AA stacking model;

[0028] Figure 2 The infrared spectrum of the TFPPY-AZO COF of the present application embodiment 1;

[0029] Figure 3 The SEM graph of the TFPPY-AZO COF of the present application embodiment 1;

[0030] Figure 4 The adsorption isotherm graph of the TFPPY-AZO COF for congo red dye of the application example 1 of the present application;

[0031] Figure 5 The adsorption kinetics graph of the TFPPY-AZO COF for congo red dye of the application example 1 of the present application;

[0032] Figure 6 The COFs material preparation flow chart of the present application. DETAILED DESCRIPTION

[0033] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0034] Please refer to Figures 1-6 A preparation method of an azo COFs material, raw materials include: aminoazobenzene monomer and aldehyde pyrene monomer, auxiliary materials include organic solvent, catalyst;

[0035] The preparation steps are as follows:

[0036] S101, after the aminoazobenzene monomer, the aldehyde pyrene monomer and the organic solvent are uniformly mixed, the catalyst is added for freezing, degassing and sealing;

[0037] S102, then standing at 120-150℃ for 7-11 days;

[0038] S103, finally, the obtained precipitate is washed and dried to obtain an azo COFs material.

[0039] Further, the aminoazobenzene monomer is p-diaminoazobenzene, and the aldehyde pyrene monomer is 1,3,6,8-tetra(4-formylphenyl)pyrene.

[0040] Further, the molar ratio of the aldehyde pyrene monomer to the aminoazobenzene monomer is 1:2.

[0041] Further, the addition amount of the organic solvent is to make the concentration of the aldehyde pyrene monomer be 0.075-0.15mmol / mL.

[0042] Further, the organic solvent is a mixed solution of o-dichlorobenzene / n-butanol or mesitylene / dioxane in a volume ratio of 1:1.

[0043] Further, the catalyst is acetic acid, and the concentration of the acetic acid is 6mol / L.

[0044] Further, the molar ratio of the aldehyde pyrene monomer to the catalyst is 1:30-40.

[0045] Further, the application of the prepared azo COFs material in adsorbing and removing Congo red dye, the COFs material is added to a solution containing different concentrations of Congo red dye, and after shaking bed oscillation for 24h, filtration is performed, and the application is completed.

[0046] The concentration range of the Congo red dye with different concentrations is 10-100ppm.

[0047] wherein the COFs material is added to a 75 ppm Congo red dye solution, stirred for different time, and filtered;

[0048] wherein the different time ranges from 0-240 min;

[0049] wherein the filtration microporous filter membrane pore size is 0.22 μm.

[0050] The COFs material preparation method prepared by the present application will be further illustrated by examples as follows:

[0051] A preparation method of an azo TFPPY-AZO COF material, specifically comprising the following steps:

[0052] A mixture of TFPPY (23.2 mg, 0.0375 mmol), AZO (15.9 mg, 0.075 mmol) and o-dichlorobenzene / n-butanol (1:1, 1 mL) is loaded into a 15 mL heat-resistant glass tube, ultrasonic treatment for 15 min, then 0.1 mL of acetic acid solution (6M) is added, and then it is quickly frozen in a liquid nitrogen bath, degassed by three freeze-pump-thaw cycles, and flame sealed under vacuum;

[0053] After being warmed to room temperature, the sealed tube is placed in a 120°C oven, and left for 7 days. The generated precipitate is collected by filtration, washed with ethanol, tetrahydrofuran and acetone in sequence, and finally dried at 80°C under vacuum for 12 h to obtain a black solid, which is an azo TFPPY-AZO COF material;

[0054] The structure of the prepared TFPPY-AZO COF is measured by a powder X-ray diffractometer (PXRD), which is a covalent organic framework with high crystallinity, and the results are shown in Figure 1 The black bold curve part; the theoretical PXRD spectrum of the COF under AA stacking conditions can be derived according to the software Materials Studio (thin line part in the figure); the experimentally measured TFPPY-AZO COF powder has 2.9°, 6.2°, and 9.2° in the 2θ angle, corresponding to the 100, 110 and 001 crystal planes of the COF; the experimental results match the characteristic peaks of the derived theoretical PXRD spectrum, indicating that the prepared TFPPY-AZO COF material is successfully synthesized.

[0055] Fourier transform infrared (FT-IR) is used to characterize the chemical bonding mode of the TFPPY-AZO COF. The results are shown in Figure 2 , the N-H characteristic peak of the TFPPY-AZO COF disappears at 3370 cm -1 , and the characteristic peak of the C=O group appears at 1700 cm -1The characteristic peak of C=O is greatly reduced, and a C=N characteristic peak appears at 1640 cm -1 The characteristic peak of C=O is greatly reduced, and a C=N characteristic peak appears at 1640 cm

[0056] The morphology of the TFPPY-AZO COF was characterized by scanning electron microscopy (SEM), and the results are shown in Figure 3 The TFPPY-AZO COF has a rough surface and a spherical structure, which is beneficial to the adsorption of Congo red dye and improves the adsorption capacity of Congo red dye.

[0057] The SEM and infrared characterization results show that the present application successfully prepared an azo TFPPY-AZO COF material.

[0058] The application of the COF material prepared by the present application is as follows:

[0059] The TFPPY-AZO COF material prepared in the example was applied to the adsorption and removal of Congo red dye, and the specific steps are as follows:

[0060] (1) Adsorption isotherm of TFPPY-AZO COF on Congo red dye

[0061] 5mg of TFPPY-AZO COF prepared in Example 1 was added to 10mL of solution containing different concentrations (10-100ppm) of Congo red dye, and the suspension was placed in a shaking bed for 24h, and then filtered through a 0.22μm microporous filter; the residual concentration of Congo red dye in the filtrate was determined by ultraviolet-visible spectrophotometry, and the adsorption capacity of TFPPY-AZO COF on Congo red dye was calculated, and the results are shown in Figure 4 The adsorption capacity of TFPPY-AZO COF on Congo red dye increases with the increase of the concentration of Congo red dye, until it reaches the adsorption equilibrium state, and the maximum adsorption capacity of TFPPY-AZO COF on Congo red dye is 240mg / g;

[0062] (2) Adsorption kinetics of TFPPY-AZO COF on Congo red dye

[0063] 5mg of TFPPY-AZO COF was dispersed in a Congo red dye (10mL 75ppm) solution, and a constant temperature shaker was used for shaking for 240min, and then filtered through a 0.22μm microporous filter, and the residual concentration of Congo red dye in the filtrate at different times was determined by ultraviolet-visible spectrophotometry, and the adsorption capacity of TFPPY-AZO COF on Congo red dye at that time was calculated, and the results are shown in Figure 5 It can be seen that the recovery rate of TFPPY-AZO COF on Congo red dye reaches 78% within 30min, which is better than other adsorbents reported before.

[0064] From the above, the TFPPY-AZO COF prepared by the method has super-high adsorption capacity and fast adsorption kinetics for Congo red dye, and can be used for adsorption and removal of Congo red dye in an aqueous solution.

[0065] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. Use of a COFs material containing an azo group in the adsorption and removal of Congo red dye, characterized by: The preparation steps of the azo group-containing COFs material are as follows: S101, the aminoazobenzene monomer, aldehyde pyrene monomer and organic solvent are mixed uniformly, and then a catalyst is added for freezing, degassing and sealing; The aminoazobenzene monomer is p-diaminoazobenzene, and the aldehyde pyrene monomer is 1,3,6,8-tetrakis(4-formylphenyl)pyrene; The molar ratio of the aldehyde pyrene monomer to the aminoazobenzene monomer is 1:2; The addition amount of the organic solvent is to make the concentration of the aldehyde pyrene monomer 0.075-0.15 mmol / mL; The organic solvent is a mixture of o-dichlorobenzene / n-butanol with a volume ratio of 1:1; S102, then standing at 120-150℃ for 7-11 days; S103, finally, the obtained precipitate is washed and dried to obtain an azo COFs material.

2. Use of the azo COFs material according to claim 1 for adsorbing and removing Congo red dye, characterized in that: The catalyst is acetic acid, and the concentration of the acetic acid is 6 mol / L.

3. Use of the azo COFs material according to claim 1 for adsorbing and removing Congo red dye, characterized in that: The molar ratio of the aldehyde pyrene monomer to the catalyst is 1:30-40.

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