A functionalized TpPa-1 covalent organic framework, its preparation method and application

Abstract

This invention belongs to the field of environmental protection new materials technology, and discloses a functionalized TpPa-1 covalent organic framework, its preparation method, and its application. The preparation method includes the following steps: preparing a TpPa-1 covalent organic framework substrate by static reaction of p-phenylenediamine and trialdehyde-resorcinol at room temperature under scandium trifluoromethanesulfonate catalysis; ultrasonically modifying the TpPa-1 covalent organic framework substrate with alkaline solution NaOH or KOH; washing with water and methanol sequentially; and drying to obtain the functionalized TpPa-1 covalent organic framework. The functionalized TpPa-1 material prepared by this invention has a rich porous structure and exhibits a fast adsorption rate and strong adsorption capacity for both single heavy metal ions and mixed heavy metal ions. It solves the problems of low removal efficiency, slow adsorption rate, and limited adsorption capacity of existing adsorption materials for heavy metal ions, and has good application prospects in the treatment and purification of heavy metal polluted water.

Description

Technical Field

[0001] This invention belongs to the field of environmentally friendly new materials technology, specifically relating to a functionalized TpPa-1 covalent organic framework, its preparation method, and its application. Background Technology

[0002] Heavy metals (including lead, cadmium, chromium, copper, nickel, cobalt, and manganese) are widely present in the environment. While some heavy metals, like lead, cadmium, and chromium, are not essential for human life and are highly toxic, others, such as copper and nickel, are essential trace elements. However, all heavy metals can be harmful to humans, even fatal, when their concentrations exceed certain limits. For example, although copper is essential for life, it is also toxic to organisms; incidents of oysters turning green due to copper contamination have occurred in some areas near harbors. Heavy metal ions are not easily degraded in the environment and exhibit bioaccumulation. Although the concentration of heavy metal ions discharged from wastewater treatment effluent is very low, they can accumulate and migrate through the food chain after entering the ecosystem, posing a serious threat to human health and the ecosystem. When heavy metals exceed a certain concentration in the human body, they can inhibit the activity of enzymes, deform hemoglobin, disrupt biochemical reactions, and thus cause disease. Currently, heavy metal ion pollution in water sources is a major problem facing drinking water safety. Researching efficient, green, and pollution-free treatment processes for removing various trace heavy metal ions from drinking water is of great significance.

[0003] Adsorption methods, with their advantages of low cost, energy efficiency, environmental friendliness, and lack of toxic byproducts, have been widely used for treating heavy metal ion pollutants in water. However, traditional adsorbents suffer from drawbacks such as low adsorption efficiency, small specific surface area, low adsorption capacity, and weak affinity for heavy metal ions. Metal-organic frameworks (MOFs), with their large specific surface area, high porosity, and easily tunable structure, are considered excellent adsorbents for heavy metal ions. However, MOFs face challenges in practical water purification applications, including poor stability and limited adsorption sites. In contrast, covalent organic frameworks (COFs), organic porous materials with a periodic network structure formed by covalent bonds connecting light elements, not only possess advantages such as high specific surface area, regular and ordered pores, and ease of functionalization, but also exhibit good thermal and chemical stability, making them a highly promising adsorbent for water purification. Imine-based COFs exhibit high stability in acidic, alkaline, and high-temperature environments, and possess a well-defined crystalline porous structure and relatively simple building blocks, making them a primary research focus in the field of COFs materials. The porous structure and molecular framework of COFs (Chemical Oxide-Foil) materials determine their properties. Their topology can be controlled by rationally selecting functional organic monomers or introducing functional groups after synthesis to meet specific functions for specific applications. Therefore, researchers often utilize the chelation effect between specific active groups and heavy metal ions to pre-design specific functional monomers to prepare functionalized COFs with specific pore sizes, or introduce specific functional groups into the synthesized COF structure to selectively remove heavy metal ions from polluted water. However, while functionalized COFs prepared by these methods can achieve highly selective adsorption of specific heavy metal ions, their adsorption efficiency and removal effect on other heavy metal ions are low, greatly limiting the application of these materials in practical water purification. Summary of the Invention

[0004] In view of the problems and shortcomings of the existing technology, the purpose of this invention is to provide a functionalized TpPa-1 covalent organic framework and its preparation and application.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The first aspect of this invention provides a method for preparing a functionalized TpPa-1 covalent organic framework, comprising the following steps:

[0007] (1) TpPa-1 covalent organic framework substrate was prepared by reacting p-phenylenediamine and trialdehyde phloroglucinol at room temperature under the catalysis of scandium trifluoromethanesulfonate.

[0008] (2) The TpPa-1 covalent organic framework substrate prepared in step (1) was ultrasonically modified using an alkaline solution. The modified substrate was washed with water and methanol in sequence and then dried to obtain the functionalized TpPa-1 covalent organic framework material.

[0009] The alkaline solution is an aqueous solution of NaOH or KOH.

[0010] Preferably, the concentration of the alkaline solution is 0.1 to 2 mol / L.

[0011] Preferably, the drying temperature in step (2) is 50-100°C and the drying time is 10-24 hours.

[0012] Preferably, the molar ratio of p-phenylenediamine and trialdehyde phloroglucinol in step (1) is 3:2, and the molar ratio of p-phenylenediamine and scandium trifluoromethanesulfonate is (25-100):1.

[0013] Preferably, in step (1), p-phenylenediamine and trialdehyde phloroglucinol are dissolved in a mixed solvent, wherein the mixed solvent is composed of 1,4-dioxane and 1,3,5-trimethylbenzene in a volume ratio of (1-5):1.

[0014] Preferably, after the reaction in step (1) is completed, the insoluble matter is separated from the reaction solution, and the insoluble matter is washed and dried to obtain the TpPa-1 covalent organic framework substrate.

[0015] More preferably, the detergent for washing away insoluble substances is at least one of methanol, ethanol, and acetone.

[0016] A second aspect of the present invention provides a functionalized TpPa-1 covalent organic framework material prepared using the method described in the first aspect.

[0017] The third aspect of this invention provides the application of the functionalized TpPa-1 covalent organic framework material as described in the second aspect above in the adsorption and removal of heavy metal ions in water.

[0018] Preferably, the heavy metal ions are one or more selected from cadmium ions, lead ions, trivalent chromium ions, cobalt ions, copper ions, nickel ions, and manganese ions.

[0019] More preferably, when the functionalized TpPa-1 covalent organic framework is used as an adsorbent in water, 0.05g to 10g of the functionalized TpPa-1 material can be added per liter in water with a heavy metal ion concentration of 0.01mg / L to 20mg / L.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) This invention employs an alkaline solution to ultrasonically modify the TpPa-1 covalent organic framework substrate, resulting in a rich porous structure on the surface of the TpPa-1 substrate, effectively increasing its specific surface area. Based on the hierarchical porous structure of the material surface and Na... + and K + Due to the ion exchange effect, the modified functionalized TpPa-1 materials (NaOH-TpPa-1 and KOH-TpPa-1) exhibit the advantages of fast adsorption rate and high adsorption capacity for both single heavy metal ions and mixed heavy metal ions.

[0022] (2) Compared with existing modified covalent organic framework materials for heavy metal ion adsorption, the method of preparing functionalized TpPa-1 materials at room temperature in this invention is simpler to operate and milder in conditions, avoiding damage to the substrate and modified material structure caused by high temperature and high pressure. The entire synthesis process is short and highly reproducible, easy to industrialize, and suitable for commercial promotion. Attached Figure Description

[0023] Figure 1 The images show the X-ray diffraction (XRD) patterns of the functionalized TpPa-1 materials in Examples 1 and 2 of this invention and the unmodified TpPa-1 substrate in Comparative Example 1.

[0024] Figure 2 The images shown are scanning electron microscope (SEM) images of the functionalized TpPa-1 materials in Examples 1 and 2 of the present invention and the unmodified TpPa-1 substrate in Comparative Example 1; wherein a is a scanning electron microscope (SEM) image of the unmodified TpPa-1 substrate in Comparative Example 1; b is a scanning electron microscope (SEM) image of the NaOH-TpPa-1 functionalized material in Example 1; and c is a scanning electron microscope (SEM) image of the KOH-TpPa-1 functionalized material in Example 2.

[0025] Figure 3 The N2 adsorption-desorption curves (BET) of the functionalized TpPa-1 material in Examples 1 and 2 of the present invention and the unmodified TpPa-1 substrate in Comparative Example 1 are shown.

[0026] Figure 4 The images show the adsorption of mixed heavy metal ions by the functionalized TpPa-1 material in Examples 1 and 2 of this invention in different solution pH values ​​in a mixed multi-component system; where a is the adsorption of mixed heavy metal ions by the NaOH-TpPa-1 functionalized material in Example 1 in different solution pH values; and b is the adsorption of mixed heavy metal ions by the KOH-TpPa-1 functionalized material in Example 2 in different pH solutions.

[0027] Figure 5The images show the thermodynamic adsorption diagrams of the functionalized TpPa-1 materials in Examples 1 and 2 of this invention for seven heavy metal ions in a single heavy metal ion system; where a is the thermodynamic adsorption diagram of the NaOH-TpPa-1 functionalized material in Example 1 for seven heavy metal ions; and b is the thermodynamic adsorption diagram of the KOH-TpPa-1 functionalized material in Example 2 for seven heavy metal ions.

[0028] Figure 6 The images show the kinetic adsorption diagrams of the functionalized TpPa-1 materials in Examples 1 and 2 of this invention for seven heavy metal ions in a single heavy metal ion system; where a is the kinetic adsorption diagram of the NaOH-TpPa-1 functionalized material in Example 1 for seven heavy metal ions; and b is the kinetic adsorption diagram of the KOH-TpPa-1 functionalized material in Example 2 for seven heavy metal ions.

[0029] Figure 7 The images show the adsorption of mixed heavy metal ions by the functionalized TpPa-1 material in Examples 1 and 2 of this invention at different initial concentrations in a mixed multi-component system; where a is the adsorption of mixed heavy metal ions by the NaOH-TpPa-1 functionalized material in Example 1 at concentrations of 0.01, 0.05, and 0.1 mg / L, respectively; and b is the adsorption of mixed heavy metal ions by the KOH-TpPa-1 functionalized material in Example 2 at concentrations of 0.01, 0.05, and 0.1 mg / L, respectively. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0031] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] (I) Preparation of Functionalized TpPa-1 Covalent Organic Framework Materials

[0033] Example 1

[0034] A method for preparing a functionalized TpPa-1 covalent organic framework material includes the following steps:

[0035] (1) Weigh 126.2 mg of trialdehyde phloroglucinol and 97.3 mg of p-phenylenediamine into a 50 mL conical flask, and add 19.2 mL of 1,4-dioxane and 4.8 mL of 1,3,5-trimethylbenzene to it. Sonicate to dissolve it, and let it stand at room temperature for 15 min to obtain solution A.

[0036] (2) Add 18 mg of scandium trifluoromethanesulfonate to solution A, sonicate to dissolve it, and let it stand at room temperature for 15 min to obtain solution B;

[0037] (3) The insoluble matter obtained by centrifugation of solution B was washed three times by centrifugation with methanol and then vacuum dried at 80°C for 12 hours. The resulting material is called TpPa-1 substrate.

[0038] (4) Weigh 300 mg of TpPa-1 substrate and disperse it in 300 mL of 1 mol / L NaOH aqueous solution. Sonicate for 30 min, centrifuge and separate, then wash with water and methanol 3 times each, and vacuum dry at 80 °C for 12 h. The resulting material is called NaOH-TpPa-1 functionalized material.

[0039] Example 2

[0040] A method for preparing a functionalized TpPa-1 covalent organic framework is basically the same as that in Example 1, except that the alkaline solution modifier in step (4) is replaced by KOH instead of NaOH, and the resulting material is denoted as KOH-TpPa-1 functionalized material.

[0041] Comparative Example 1

[0042] A method for preparing an unmodified TpPa-1 covalent organic framework substrate, which is basically the same as the method in Example 1, except that step (4) is omitted.

[0043] Comparative Example 2

[0044] A method for preparing a functionalized TpPa-1 covalent organic framework is basically the same as that in Example 1, except that the NaOH aqueous solution in step (4) is replaced with ammonia water, and the resulting material is denoted as functionalized NH4OH-TpPa-1 material.

[0045] Comparative Example 3

[0046] A method for preparing a functionalized TpPa-1 covalent organic framework is basically the same as that in Example 1, except that the NaOH aqueous solution in step (4) is replaced with a neutral NaCl solution, and the resulting material is referred to as the functionalized NaCl-TpPa-1 material.

[0047] Comparative Example 4

[0048] A method for preparing a functionalized TpPa-1 covalent organic framework is basically the same as that in Example 1, except that the NaOH aqueous solution in step (4) is replaced with a neutral KCl solution, and the resulting material is denoted as functionalized KCl-TpPa-1 material.

[0049] (II) Structural characterization of functionalized TpPa-1 materials

[0050] The crystal structure, surface morphology, and specific surface area of ​​the functionalized TpPa-1 covalent organic frameworks (NaOH-TpPa-1, KOH-TpPa-1) prepared in Examples 1 and 2 and the unmodified TpPa-1 substrate prepared in Comparative Example 1 were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and N2 adsorption-desorption experiments (BET plots).

[0051] Figure 1 The figures show the XRD patterns of the functionalized TpPa-1 covalent organic frameworks (NaOH-TpPa-1 and KOH-TpPa-1) prepared in Examples 1 and 2, and the unmodified TpPa-1 substrate prepared in Comparative Example 1. As can be seen from the figures, diffraction peaks were observed at 4.8°, 8.4°, 12.7°, 14.6°, and 27.0° for all three materials: NaOH-TpPa-1, KOH-TpPa-1, and the unmodified TpPa-1 substrate. These peaks were caused by reflections from the

[100] ,

[110] ,

[111] ,

[120] , and

[001] crystal planes of the materials, respectively. The intensity of the diffraction peaks did not change significantly. This indicates that the unmodified TpPa-1 substrate and the functionalized TpPa-1 material were successfully prepared, and that the modification treatment of the TpPa-1 substrate by NaOH or KOH did not change the original crystal structure of the covalent organic framework.

[0052] Figure 2 These are scanning electron microscope (SEM) images of the functionalized TpPa-1 materials prepared in Examples 1-2 and the unmodified TpPa-1 substrate prepared in Comparative Example 1. The unmodified TpPa-1 substrate of Comparative Example 1... Figure 2 a) NaOH-TpPa-1 material of Example 1 ( Figure 2 b) and the KOH-TpPa-1 material of Example 2 ( Figure 2 c). By Figure 2As can be seen, the unmodified TpPa-1 substrate is an aggregate of spherical particles with no obvious pores on the surface, a relatively dense structure, and a particle size of about 1 μm. The surface morphology of the NaOH-TpPa-1 functionalized material obtained after NaOH modification is very different from that of the unmodified TpPa-1 material. The NaOH-TpPa-1 material consists of spherical particles with a relatively rough surface and a rich porous structure, and a particle size of about 1 μm. The morphology of the KOH-TpPa-1 functionalized material obtained after KOH modification is similar to that of the NaOH-TpPa-1 functionalized material, also exhibiting spherical particles with a rough surface and a rich porous structure, and a particle size of about 1 μm.

[0053] Figure 3 The specific surface areas of the functionalized TpPa-1 covalent organic frameworks (NaOH-TpPa-1 and KOH-TpPa-1) prepared in Examples 1 and 2, and the unmodified TpPa-1 substrate prepared in Comparative Example 1, are given. The BET specific surface areas of the unmodified TpPa-1 substrate, the functionalized NaOH-TpPa-1, and the functionalized KOH-TpPa-1 materials are calculated to be 47.1 m². 2 / g, 138.2m 2 / g and 107.5m 2 / g. This result indicates that both NaOH and KOH modification treatments effectively increased the specific surface area of ​​the TpPa-1 substrate, combined with Figure 2 Morphological analysis suggests that the modification with NaOH and KOH resulted in a greater number of microporous structures in the TpPa-1 substrate, which is beneficial for improving the adsorption capacity for heavy metal ions.

[0054] (III) Study on the adsorption performance of functionalized TpPa-1 materials prepared under different modification conditions for various heavy metal ions in water

[0055] The adsorption performance of the TpPa-1 covalent organic framework materials prepared in Examples 1-2 and Comparative Examples 1-4 on seven mixed heavy metal ions in water was evaluated. The specific experimental procedure was as follows: A certain mass of metal salts (cadmium chloride (CdCl2), lead nitrate (Pb(NO3)2), chromium trichloride (CrCl3), cobalt chloride hexahydrate (CoCl2·6H2O), copper chloride (CuCl2), nickel chloride (NiCl2), and manganese chloride (MnCl2)) were weighed and dissolved in water with pH=2 to prepare heavy metal ion aqueous solutions with a concentration of 1000 mg / L as stock solutions. The stock solutions of heavy metal ions were then diluted with pure water to prepare mixed solutions of seven heavy metal ions with a concentration of 0.1 mg / L and a pH=6 as working solutions. 3 mg of the TpPa-1 covalent organic framework materials prepared in Examples 1-2 and Comparative Examples 1-4 were weighed into 50 mL centrifuge tubes, and 30 mL of the solution was added to each tube. A 0.1 mg / L aqueous solution of seven mixed heavy metal ions was prepared and shaken at room temperature for 12 h. The centrifuge tube was then centrifuged at 10,000 rpm for 5 min. The supernatant was collected and the content of heavy metal ions in the supernatant was determined by ICP-MS. The equilibrium adsorption rate of heavy metal ions by TpPa-1 covalent organic framework material was calculated.

[0056] The formula for calculating the equilibrium adsorption rate is as follows:

[0057] Adsorption rate % = (c0 - c) t ) / c0×100%

[0058] Among them, c0 (mg / L) and c t (mg / L) refers to the initial concentration of heavy metal ions and the concentration of heavy metal ions in the system solution at time t, respectively.

[0059] The specific adsorption results are shown in Table 1:

[0060] Table 1 shows the adsorption rates of the materials prepared in Examples 1-2 and Comparative Examples 1-4 for seven heavy metal ions in the mixed solution.

[0061]

[0062] As shown in Table 1, the unmodified TpPa-1 substrate prepared in Comparative Example 1 exhibited poor adsorption performance for the seven heavy metal ions in water, with adsorption rates ranging from 10.7% to 35.2%. Compared to the unmodified TpPa-1 substrate prepared in Comparative Example 1, the functionalized TpPa-1 covalent organic frameworks (NaOH-TpPa-1 and KOH-TpPa-1) prepared in Examples 1-2 showed excellent adsorption performance for the seven heavy metal ions in water, with adsorption rates of 98.4%–100% and 97.2%–100%, respectively. Furthermore, in Comparative Examples 2-4, other solutions (such as ammonia, NaCl, and KCl) were used as modifiers to modify the TpPa-1 substrate. The results showed that the prepared functionalized TpPa-1 covalent organic frameworks all exhibited poor adsorption performance for the seven heavy metal ions in water. The above results demonstrate that the modification of the TpPa-1 substrate with NaOH or KOH significantly improves the adsorption capacity of the original substrate for various heavy metal ions, and is far superior to the adsorption effect of functionalized TpPa-1 prepared using other commonly used alkaline solutions such as ammonia or neutral solutions as modifiers. This may be due to the effective increase in the specific surface area of ​​the TpPa-1 material by the modification with NaOH and KOH, and the formation of Na+ in the porous TpPa-1 material. + and K + This is due to the dual function of ion channels.

[0063] (IV) Study on the adsorption process of various heavy metal ions by functionalized TpPa-1 covalent organic framework materials

[0064] The functionalized TpPa-1 materials prepared in Example 1 (NaOH-TpPa-1) and Example 2 (KOH-TpPa-1) were used as experimental materials to study the adsorption process of various heavy metal ions by the materials of the present invention.

[0065] 1. Study on the effect of pH on adsorption solution

[0066] (1) Experimental methods

[0067] A certain mass of metal salts (cadmium chloride (CdCl2), lead nitrate (Pb(NO3)2), chromium trichloride (CrCl3), cobalt chloride hexahydrate (CoCl2·6H2O), copper chloride (CuCl2), nickel chloride (NiCl2), and manganese chloride (MnCl2)) were weighed and dissolved in water with pH=2 to prepare 1000 mg / L heavy metal ion aqueous solutions as stock solutions. The stock solutions were then diluted with pure water to prepare a mixed solution of the seven heavy metal ions with a concentration of 0.1 mg / L as the working solution. A 0. The pH of the working solution was adjusted with 1 mol / L HCl or NaOH to obtain mixed heavy metal ion working solutions with different pH values ​​(4, 5, 6, 7, 8) at 0.1 mg / L. 3 mg of functionalized TpPa-1 material was accurately weighed and placed in a 50 mL centrifuge tube. Then, 30 mL of 0.1 mg / L aqueous solutions of the seven mixed heavy metal ions with different pH values ​​were added to each tube. The mixture was shaken and adsorbed at room temperature for 12 h. The centrifuge tube was centrifuged at 10,000 rpm for 5 min, and the content of heavy metal ions in the supernatant was determined by ICP-MS.

[0068] (2) Results Analysis

[0069] Figure 4 The NaOH-TpPa-1 (prepared in Example 1) in the mixed multi-component system are respectively Figure 4 a) and KOH-TpPa-1 prepared in Example 2 ( Figure 4 b) Adsorption diagrams of functionalized TpPa-1 material for seven mixed heavy metal ions at different solution pH values. From Figure 4 As shown in a and 4b, when the solution pH = 4, both functionalized TpPa-1 materials, NaOH-TpPa-1 and KOH-TpPa-1, exhibit significant adsorption effects on the seven heavy metal ions, with adsorption rates of 14.2%–90.4% and 13.0%–90.4%, respectively. These adsorption rates are superior to those of the unmodified TpPa-1 substrate for the mixed heavy metal ions (adsorption rate of 0.7%–33.2% at pH = 4, and adsorption rate at pH = 6, as shown in Comparative Example 1 in Table 1). When the solution pH is in the range of 5–8, the adsorption capacity of NaOH-TpPa-1 and KOH-TpPa-1 materials is significantly enhanced, and both can achieve near-complete adsorption of the seven heavy metal mixed ions. These results demonstrate that the functionalized TpPa-1 materials, such as NaOH-TpPa-1 and KOH-TpPa-1, prepared in this invention can achieve efficient adsorption and removal of multiple mixed heavy metal ions in water over a wide pH range.

[0070] 2. Study on thermodynamic adsorption properties

[0071] (1) Experimental methods

[0072] Weigh out a certain mass of metal salts (cadmium chloride (CdCl2), lead nitrate (Pb(NO3)2), chromium trichloride (CrCl3), cobalt chloride hexahydrate (CoCl2·6H2O), copper chloride (CuCl2), nickel chloride (NiCl2), and manganese chloride (MnCl2)) and dissolve them in water at pH=2 to prepare 1000 mg / L heavy metal ion aqueous solutions as stock solutions. Then, dilute the stock solutions with pure water to prepare single heavy metal ion standard solutions (pH=6) with concentrations of 0.01, 0.05, 0.1, 0.5, 1, 5, and 10 mg / L respectively as working solutions; accurately weigh 3 mg The NaOH-TpPa-1 or KOH-TpPa-1 functionalized materials were placed in 50 mL centrifuge tubes, and then 30 mL of aqueous solutions of single heavy metal ions with different initial concentrations were added. The tubes were shaken and adsorbed at room temperature for 12 h. The tubes were then centrifuged at 10000 rpm for 5 min, and the supernatant was collected for ICP-MS analysis to determine the content of metal ions. The equilibrium adsorption capacity for the seven heavy metal ions was calculated. The formula for calculating the equilibrium adsorption capacity is as follows:

[0073] Q = (c0 - c) t )v / m

[0074] Where Q (mg / g) refers to the adsorption capacity of the adsorbent material, and c0 (mg / mL) and c t (mg / mL) refers to the initial concentration of heavy metal ions and the concentration of ions in the system solution at time t, respectively; v (mL) refers to the volume of the adsorption solution; and m (g) refers to the mass of the adsorption material.

[0075] (2) Results Analysis

[0076] Figure 5 Figures a and 5b show the thermodynamic adsorption curves of seven single heavy metal ions in water for the NaOH-TpPa-1 functionalized material prepared in Example 1 and the KOH-TpPa-1 functionalized material prepared in Example 2, respectively. As can be seen from the figures, the adsorption capacity of the seven heavy metal ions on the NaOH-TpPa-1 and KOH-TpPa-1 functionalized materials increases with increasing initial concentration. When the initial concentration of heavy metal ions is 10 mg / L, the NaOH-TpPa-1 material, except for Pb... 2+ The adsorption of Pb by KOH-TpPa-1 has not yet reached saturation, while the adsorption of the other six heavy metal ions has basically reached saturation. 2+ and Cr 3+ The adsorption of Pb was not saturated, while the adsorption of the other five heavy metal ions was basically saturated. The equilibrium adsorption amounts of these seven heavy metal ions in the NaOH-TpPa-1 functionalized material were as follows: 2+ >Cr 3+ >Cu2+ ≈Cd 2+ >Co 2+ ≈Ni 2+ ≈Mn 2+ The equilibrium adsorption capacity of the KOH-TpPa-1 functionalized material is: Pb 2+ >Cr 3+ >Cu 2+ ≈Cd 2+ ≈Co 2+ Ni 2+ ≈Mn 2+ Pb can be found 2+ and Cr 3+ It exhibits strong adsorption capacity on NaOH-TpPa-1 and KOH-TpPa-1 functionalized materials, especially for Pb. 2+ It has the strongest adsorption capacity.

[0077] 3. Study on kinetic adsorption performance

[0078] (1) Experimental methods

[0079] Weigh out specific masses of metal salts (cadmium chloride (CdCl2), lead nitrate (Pb(NO3)2), chromium trichloride (CrCl3), cobalt chloride hexahydrate (CoCl2·6H2O), copper chloride (CuCl2), nickel chloride (NiCl2), and manganese chloride (MnCl2)) and dissolve them in water with pH=2 to prepare 1000 mg / L heavy metal ion aqueous solutions as stock solutions. Then, dilute the stock solutions with pure water to prepare 0.1 mg / L single heavy metal ion standard solutions (pH=6) as working solutions. Accurately weigh... 3 mg of NaOH-TpPa-1 or KOH-TpPa-1 functionalized material was placed in a 50 mL centrifuge tube. Then, 30 mL of 0.1 mg / L single heavy metal ions was added to each tube. The tubes were shaken at room temperature for different adsorption times (10 s, 20 s, 30 s, 1 min, 5 min, 10 min, 20 min, 30 min, 60 min). The tubes were then centrifuged at 10000 rpm for 5 min. The supernatant was collected, and the metal ion content was determined by ICP-MS. The equilibrium adsorption capacity for the seven heavy metal ions was calculated. The formula for calculating the equilibrium adsorption capacity is as follows:

[0080] Q = (c0 - c) t )v / m

[0081] Where Q (mg / g) refers to the adsorption capacity of the adsorbent material, and c0 (mg / mL) and c t (mg / mL) refers to the initial concentration of heavy metal ions and the concentration of ions in the system solution at time t, respectively; v (mL) refers to the volume of the adsorption solution; and m (g) refers to the mass of the adsorption material.

[0082] (2) Results Analysis

[0083] Figure 6 a and 6b are the kinetic adsorption curves of seven single heavy metal ions in water for the NaOH-TpPa-1 and KOH-TpPa-1 functionalized materials prepared in Examples 1 and 2, respectively. Figure 6 As can be seen from a, the NaOH-TpPa-1 functionalized material exhibits a fairly fast adsorption rate for these seven heavy metal ions, except for Cr. 3+ In addition, within just 20 seconds, the adsorption rate of NaOH-TpPa-1 for the other six heavy metal ions was over 95%. Within 5 minutes, the adsorption of these six heavy metal ions reached equilibrium. At 60 minutes, the adsorption rate for Cr... 3+ The adsorption rate can reach 77%. The kinetic adsorption behavior of KOH-TpPa-1 functionalized materials for these seven heavy metal ions is basically consistent with that of NaOH-TpPa-1 functionalized materials. Figure 6 b shows that KOH-TpPa-1 exhibits a faster adsorption rate for the seven heavy metal ions than NaOH-TpPa-1, requiring only 10 s. KOH-TpPa-1 also shows a faster adsorption rate for Cd ions. 2+ Pb 2+ Co 2+ Cu 2+ Ni 2+ Mn 2+ and Cr 3+ The adsorption rates reached 100%, 99.0%, 99.6%, 98.5%, 92.8%, 99.9%, and 52.4%, respectively, except for Cr. 3+ In addition, the adsorption of the other six heavy metal ions by the KOH-TpPa-1 material reached equilibrium within 5 minutes, and at 60 minutes, the adsorption of Cr... 3+ The adsorption rate can reach 91.6%. These results indicate that the functionalized materials NaOH-TpPa-1 and KOH-TpPa-1 exhibit fast adsorption rates and strong adsorption capacities for all seven heavy metal ions in water.

[0084] 4. Adsorption and removal experiments of mixed heavy metal ions with different initial concentrations

[0085] (1) Experimental methods

[0086] Weigh out a certain mass of metal salts (cadmium chloride (CdCl2), lead nitrate (Pb(NO3)2), chromium trichloride (CrCl3), cobalt chloride hexahydrate (CoCl2·6H2O), copper chloride (CuCl2), nickel chloride (NiCl2), and manganese chloride (MnCl2)) and dissolve them in water at pH=2 to prepare 1000 mg / L heavy metal ion aqueous solutions as stock solutions. Then, dilute the stock solutions with pure water to prepare mixed standard solutions of the seven heavy metal ions at concentrations of 0.01, 0.05, and 0.1 mg / L (pH=6) as working solutions. In the mixed multi-component system of the seven heavy metal ions, accurately weigh 3 mg of NaOH-TpPa-1 or KOH-TpPa-1 functionalized material and place them in 50 mL centrifuge tubes, then add 30 mL of each to the tube. Mixed standard solutions of heavy metal ions at concentrations of 0.01, 0.05, and 0.1 mg / L were prepared and adsorbed by shaking at room temperature for 12 h. Centrifuge tubes were then centrifuged at 10000 rpm for 5 min, and the supernatant was used to determine the heavy metal ion content by ICP-MS. The adsorption and removal efficiency of NaOH-TpPa-1 or KOH-TpPa-1 functionalized materials for the seven heavy metal ions was calculated, and the results are as follows: Figure 7 As shown.

[0087] (2) Results Analysis

[0088] Figure 7 The figure shows the adsorption effect of NaOH-TpPa-1 or KOH-TpPa-1 functionalized materials for seven heavy metal ions at different initial concentrations in a mixed multi-component system. As can be seen from the figure, within the initial concentration range of 0.01–0.1 mg / L, the NaOH-TpPa-1 material effectively adsorbs Cd… 2+ Pb 2+ Cr 3+ Co 2+ Cu 2+ Ni 2+ and Mn 2+ The adsorption rates were 98.9–100%, 99.8–100%, 88.0–97.4%, 97.8–100%, 98.5–100%, 97.0–100%, and 98.3–100%, respectively. The KOH-TpPa-1 material showed adsorption rates of 98.9–100%, 99.8–100%, 88.0–97.4%, 97.8–100%, 98.5–100%, 97.0–100%, and 98.3–100% for Cd. 2 + Pb 2+ Cr 3+ Co 2+ Cu 2+ Ni 2+ and Mn 2+The adsorption rates were 99.8–100%, 100%, 88.3–93.4%, 98.7–99.9%, 97.8–100%, 98.3–99.8%, and 98.8–100%, respectively. After adsorption treatment with NaOH-TpPa-1 and KOH-TpPa-1 functionalized materials, the residual concentrations of the seven heavy metal ions in the solution were all far below the limits for these heavy metal ions in the Chinese national standard GB 5749-2022 "Standards for Drinking Water Quality". The results fully demonstrate that the functionalized TpPa-1 material synthesized in this invention exhibits good removal effects for multiple single heavy metal ions and multiple heavy metal ions in mixed multi-component coexisting systems, and has good practical application value.

[0089] In summary, this invention effectively overcomes the shortcomings of the prior art and has high industrial applicability. The above embodiments are intended to illustrate the substantive content of this invention, but are not intended to limit the scope of protection of this invention. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this invention without departing from the essence and scope of protection of this invention.

Claims

1. A method for preparing a functionalized TpPa-1 covalent organic framework, characterized in that, Includes the following steps: (1) TpPa-1 covalent organic framework substrate was prepared by reacting p-phenylenediamine and trialdehyde resorcinol at room temperature under the catalysis of scandium trifluoromethanesulfonate; wherein the molar ratio of p-phenylenediamine to trialdehyde resorcinol was 3:2, and the molar ratio of p-phenylenediamine to scandium trifluoromethanesulfonate was (25-100):1; p-phenylenediamine and trialdehyde resorcinol were dissolved in a mixed solvent, wherein the mixed solvent was composed of 1,4-dioxane and 1,3,5-trimethylbenzene in a volume ratio of (1-5):1; (2) The TpPa-1 covalent organic framework substrate prepared in step (1) was ultrasonically modified with an alkaline solution with a concentration of 0.1 to 2 mol / L, washed with water and methanol in sequence, and dried to obtain the functionalized TpPa-1 covalent organic framework. The alkaline solution is an aqueous solution of NaOH or KOH.

2. The preparation method according to claim 1, characterized in that, The drying temperature in step (2) is 50-100℃ and the drying time is 10-24h.

3. The preparation method according to claim 1, characterized in that, After the reaction in step (1) is completed, the insoluble matter is separated from the reaction solution, and the insoluble matter is washed and dried to obtain TpPa-1 covalent organic framework substrate.

4. The preparation method according to claim 3, characterized in that, The detergent used to remove insoluble substances is at least one of methanol, ethanol, and acetone.

5. A functionalized TpPa-1 covalent organic framework material prepared using the method described in any one of claims 1 to 4.

6. The application of the functionalized TpPa-1 covalent organic framework material according to claim 5 in the adsorption and removal of heavy metal ions in water.

7. The application according to claim 6, characterized in that, The heavy metal ions are one or more of cadmium ions, lead ions, chromium ions, cobalt ions, copper ions, nickel ions, and manganese ions.

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