CN114920907B - An aminated porous aromatic skeleton compound and its preparation method and application - Google Patents

Abstract

The invention relates to the field of environmental materials, and discloses an aminated porous aromatic skeleton compound, a preparation method and application thereof. The preparation method mainly comprises the following steps: and (3) carrying out carbon-carbon coupling reaction on the 2, 5-dibromophenyl aldehyde and the terminal alkynyl compound under the action of a catalyst to generate an intermediate product, and synthesizing and modifying the intermediate product after amino to obtain the aminated porous aromatic skeleton compound. The compound improves the PFAS adsorption selectivity, can efficiently adsorb and remove perfluoroalkyl compounds (such as perfluoroalkyl sulfonic acid and perfluoroalkyl carboxylic acid) in water, and overcomes the problems of insufficient adsorption quantity, low selectivity, slow dynamics, difficult regeneration and the like of the adsorbent in the prior art.

Description

A kind of aminated porous aromatic skeleton compound and its preparation method and application

Technical Field

The present invention relates to the technical field of environmental materials, and more specifically to an aminated porous aromatic skeleton compound and a preparation method and application thereof.

Background Art

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a class of man-made organofluorine chemicals with environmental persistence, which are widely used in industry and consumer products. Among them, perfluoroalkyl sulfonic acids (PFOS) and perfluoroalkylcarboxylic acids (PFOA) are typical PFAS, which have hydrophobic perfluoroalkyl chains and hydrophilic anionic functional groups. They are commonly found in surface water or groundwater, causing pollution to drinking water. Studies have shown that the enrichment of PFAS in living organisms can lead to health problems such as thyroid dysfunction, delayed puberty, osteoarthritis, liver problems, cholesterol changes, and immune disorders. However, PFAS molecules have strong carbon-fluorine bond energy, can resist hydrolysis, photolysis, and biodegradation, and are difficult to remove. Therefore, people try to remove PFAS from drinking water through adsorption technology.

At present, adsorption technology based on activated carbon and ion exchange resin is the most commonly used solution for removing PFAS pollutants from water, but these adsorbent materials generally have problems such as insufficient adsorption capacity, low selectivity, slow kinetics and difficulty in regeneration. Metal organic frameworks and imine-linked covalent organic frameworks have been used to effectively remove PFAS from water, but too low or too high solution pH may cause instability of MOFs and COFs frameworks. Porous polymers for PFAS removal are still in their infancy and require further research and innovation. In the prior art, aldehyde groups have been widely used to construct porous organic polymers, especially in combination with amines or hydrazides to form imine or hydrazone groups as connections between related organic molecular structural units. In organic synthesis, amine-functionalized organic compounds are usually obtained by reducing azide compounds to amines or amides. However, azide compounds are very likely to cause explosions during the reaction, posing a great threat to human life safety.

Therefore, seeking an efficient adsorption material for organic compounds that is easy to prepare, has a high adsorption capacity and a fast adsorption rate, and a simple and safe preparation method thereof is an urgent problem to be solved in the art.

Summary of the invention

In order to solve the defects of the adsorption materials in the above-mentioned prior art, such as insufficient adsorption capacity, low selectivity, slow kinetics and difficulty in regeneration, the purpose of the present invention is to provide an amino porous aromatic skeleton compound.

Another object of the present invention is to provide a method for preparing the aminated porous aromatic skeleton compounds.

Another object of the present invention is to provide an amino porous aromatic skeleton compound for use as an adsorption material in adsorbing PFAS pollutants in water.

Another object of the present invention is to provide a method for adsorbing and desorbing PFAS pollutants using aminated porous aromatic skeleton compounds as adsorbent materials.

The present invention is achieved through the following technical solutions:

An aminated porous aromatic skeleton compound includes any one of the following structural formulas:

中的任意一种。Among them, R represents

Any one of .

A method for preparing an aminated porous aromatic skeleton compound comprises the following steps:

S1. 2,5-dibromophenylaldehyde, a terminal alkynyl compound, a palladium catalyst and cuprous iodide are mixed in N,N-dimethylformamide and triethylamine, and a Sonogashira-Hagihara coupling reaction is carried out under anaerobic conditions to obtain an aldehyde-modified porous aromatic skeleton compound PAF-CHO;

S2. The aldehyde-modified porous aromatic skeleton compound PAF-CHO and excess polyamine in step S1 are dispersed in an organic solvent, and a Schiff base intermediate is obtained by condensation reaction under anaerobic conditions. A reducing agent is then added for reduction reaction, and the aminated porous aromatic skeleton compound PAF-NH ₂ is obtained after filtering, washing and drying.

Specifically, the preparation method schematic diagram includes any one of the following 12 types:

中的任意一种。Among them, R represents

Any one of .

Preferably, the 2,5-dibromophenylaldehyde in step S1 is any one of 2,5-dibromoterephthalaldehyde or 2,5-dibromobenzaldehyde.

2,5-二溴苯甲醛的结构式为

Specifically, the structural formula of 2,5-dibromoterephthalaldehyde is

The structural formula of 2,5-dibromobenzaldehyde is

Preferably, in step S1, the terminal alkynyl compound is any one of 1,3,5-tri(4-ethynylphenyl)benzene, 2,4,6-tri(4-ethynylphenyl)-1,3,5-triazine, tri(4-ethynylphenyl)amine, tetra(4-ethynylphenyl)methane, tetra(4-ethynylphenyl)ethylene or 1,3,5,7-tetra(4-ethynylphenyl)adamantane.

2,4,6-三(4-乙炔基苯基)-1,3,5-三嗪的结构式为

三(4-乙炔苯基)胺的结构式为

四(4-乙炔基苯基)甲烷的结构式为

四(4-乙炔基苯)乙烯的结构式为

1,3,5,7-四(4-乙炔基苯基)金刚烷的结构式为

Specifically, the structural formula of 1,3,5-tri(4-ethynylphenyl)benzene is

The structural formula of 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine is

The structural formula of tri(4-ethynylphenyl)amine is

The structural formula of tetrakis(4-ethynylphenyl)methane is

The structural formula of tetra(4-ethynylphenyl)ethylene is

The structural formula of 1,3,5,7-tetrakis(4-ethynylphenyl)adamantane is

Preferably, the aldehyde-formylated porous aromatic skeleton compound PAF-CHO comprises any one of the following structural formulas:

Preferably, in step S1, the molar ratio of bromine to alkynyl in the 2,5-dibromophenylaldehyde and the terminal alkynyl compound is 1:1.

Preferably, in step S1, the molar ratio of 2,5-dibromophenylaldehyde, palladium catalyst and cuprous iodide is 1:(0.1-1):(0.1-1). The volume ratio of N,N-dimethylformamide and triethylamine is 1:(0.1-1). The molar ratio of 2,5-dibromophenylaldehyde to N,N-dimethylformamide is 1mmol:(15-20)ml. The palladium catalyst is Pd(PPh ₃ ) ₄ or Pd(PPh ₃ ) ₂ Cl ₂ .

Preferably, the reaction conditions of the Sonogashira-Hagihara coupling reaction are heating under reflux at 80-120° C. for 1-3 days.

Preferably, in step S2, the polyamine is any one of ethylenediamine, propylenediamine or diethylenetriamine. The organic solvent is any one of methanol, ethanol, N,N-dimethylformamide or dimethyl sulfoxide. The reducing agent is any one of sodium borohydride, sodium cyanoborohydride or sodium triacetylborohydride. Preferably, the reaction conditions of the condensation reaction are heating under reflux at 80-120°C for 12-24h.

An amino porous aromatic skeleton compound is used as an adsorption material in the adsorption of PFAS pollutants in water.

A method for adsorbing and desorbing PFAS pollutants using the aminated porous aromatic skeleton compound as an adsorbent material comprises the following steps:

Add the aminated porous aromatic skeleton compound to the solution to be adsorbed and shake it for a sufficient time to adsorb the PFAS pollutants; after the adsorption is completed, the adsorbent material is centrifuged, desorbed and dried.

Preferably, the pH of the solution to be adsorbed is less than 7. More preferably, the pH of the solution to be adsorbed is 3. The present application unexpectedly found that acidic conditions are more conducive to the adsorption of PFAS, and at pH=3, the adsorption amount of PFOS by PAF-NH ₂ is the largest.

Preferably, the desorption treatment comprises adding the centrifuged adsorption material PAF- _NH2 to a mixed solvent of NaOH and _CH3OH for desorption by shaking. Further preferably, the temperature for desorption of the adsorption material is not less than 20°C. Further preferably, the time for desorption of the adsorption material is at least 2 hours. Specifically, the higher the temperature, the faster the desorption rate; the longer the time, the more complete the desorption degree.

Further preferably, the mixed solvent consists of 1% by mass of NaOH solution and CH ₃ OH, wherein the volume ratio of the NaOH solution to CH ₃ OH is 3:7.

Preferably, the aminated porous aromatic skeleton compounds are used as adsorbent materials in the application of adsorbing PFAS pollutants. The five common PFAS are perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), perfluorohexane sulfonic acid (PFHxS), perfluorobutane sulfonate (PFBS) and 2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy) propionate (GenX).

The present invention innovatively retains the unreacted aldehyde part during the assembly process of the porous aromatic framework (PAF), and innovatively introduces the free aldehyde part into the obtained PAF structure, and finally uses a mild Schiff base reaction method to introduce a flexible polyamino segment on the hydrophobic skeleton to obtain an amine-functionalized PAF. The preparation method uses a new one-step amine grafting post-modification strategy under relatively mild synthesis conditions, and the preparation conditions are relatively mild. The main structure of the compound prepared by the preparation method of the present invention is a carbon-carbon skeleton, which is more stable than the nitrogen-nitrogen skeleton formed by grafting amino groups into the compound through an azide reaction in the prior art, and has better adsorption performance, and can be widely used in the field of environmental materials.

Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

1. The amino porous aromatic skeleton compounds provided by the present invention are mainly composed of a carbon-carbon skeleton and a carbon-nitrogen skeleton in their structure, so the compounds have good chemical stability and thermal stability. Such compounds include a variety of compounds with various types, all of which can be used in the field of pollutant adsorption.

2. The aminated porous aromatic skeleton compound provided by the present invention contains amino functional groups and aromatic functional groups, which can utilize electrostatic and hydrophobic effects to synergistically adsorb PFAS, and the aminated pore surface not only serves as an adsorption site for PFAS anions, but also promotes the rapid diffusion of water-soluble PFAS solutions in the pores of the adsorption material, which is conducive to rapid adsorption. The adsorption rate of the compound is relatively fast, and the adsorption of five common PFAS (PFOS, PFOA, PFHxS, PFBS, GenX) can reach adsorption equilibrium within 5 to 50 minutes.

3. The aminated porous aromatic skeleton compounds provided by the present invention have a high specific surface area, and the adsorption rate of common PFAS in water can reach 50% to 95%, and the adsorption capacity is relatively strong.

4. The amino porous aromatic skeleton compound provided by the present invention has a strong anti-interference ability. Under the influence of KCl or Na ₂ SO ₄ or humic acid, its adsorption capacity can still reach 70% to 85% of the initial value.

The aminated porous aromatic skeleton compound provided by the present invention has good regeneration performance. After five cycles of adsorption and desorption treatment, the adsorption amount remains substantially unchanged, showing good adsorption regeneration performance and being environmentally friendly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1(a) is an infrared spectrum of PAF- _NH2 prepared in Example 1 and PAF-CHO prepared in Comparative Example 6; FIG1(b) is an infrared partial enlarged spectrum of FIG1(a);

FIG2(a) is a ¹³ C solid nuclear magnetic spectrum and its signal attribution; FIG2(b) is a full XPS spectrum of PAF-NH ₂ prepared in Example 1 and PAF-CHO prepared in Comparative Example 6;

Figures 3(a) and 3(b) are scanning electron micrographs of PAF-CHO prepared in Comparative Example 6; Figures 3(c) and 3(d) are scanning electron micrographs of PAF- _NH2 prepared in Example 1; Figure 3(e) is a transmission electron micrograph of PAF-CHO prepared in Comparative Example 6; Figure 3(f) is a transmission electron micrograph of PAF- _NH2 prepared in Example 1;

FIG4 is a diagram showing the adsorption kinetics of five common PFAS (PFOS, PFOA, PFHxS, PFBS, GenX) by the amino porous aromatic skeleton compound PAF- _NH2 prepared in Example 1;

FIG5(a) is the adsorption isotherms of the aminated porous aromatic skeleton compound PAF- _NH2 prepared in Example 1 for PFBS and GenX in water by Langmuir and Freundlich simulation, respectively; FIG5(b) is the adsorption isotherms of the aminated porous aromatic skeleton compound PAF- _NH2 prepared in Example 1 for PFOS, PFOA and PFHxS in water by Langmuir and Freundlich simulation, respectively;

FIG6(a) is a graph showing the adsorption of PFOS in water by the aminated porous aromatic skeleton compound PAF- _NH2 prepared in Example 1 under different pH conditions; FIG6(b) is a graph showing the cyclic adsorption of PFOS in water by the aminated porous aromatic skeleton compound PAF- _NH2 prepared in Example 1 of the present invention;

FIG. 7( a ) is a graph showing the adsorption of PFOS in water by the aminated porous aromatic skeleton compound PAF-NH ₂ prepared in Example 1 under the interference of humic acid; FIG. 7( b ) is a graph showing the adsorption of PFOS in water by the aminated porous aromatic skeleton compound PAF-NH ₂ prepared in Example 1 of the present invention under the interference of SO ₄ ^2- /Cl ^- ;

FIG8 is a graph showing the adsorption of PFOS in water by the aminated porous aromatic skeleton compounds prepared in Example 1 and Comparative Examples 1 to 3;

Figure 9(a) is a comparison of the adsorption results of the amino porous aromatic skeleton compound PAF- _NH2 prepared in Example 1 and PAF-CHO prepared in Comparative Example 6 for five common PFAS (PFOS, PFOA, PFHxS, PFBS, GenX) in water; Figure 9(b) is a diagram of the adsorption kinetics of PFOS in water by the amino porous aromatic skeleton compound PAF- _NH2 prepared in Example 1 and PAF-CHO prepared in Comparative Example 6.

DETAILED DESCRIPTION

In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the present application will be clearly and completely described below in conjunction with the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the described embodiments, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

The present invention is further described below in conjunction with the accompanying drawings and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

Example 1

The embodiment of the present invention provides an aminated porous aromatic skeleton compound and a preparation method thereof.

The synthetic route is as follows:

The specific steps are as follows:

S1: Weigh 0.263 g (0.90 mmol) of 2,5-dibromoterephthalaldehyde, 0.227 g (0.60 mmol) of 1,3,5-tris(4-ethynylphenyl)benzene, 0.150 g (0.21 mmol) of Pd(PPh ₃ ) ₄ , 0.050 g (0.26 mmol) of CuI, and weigh 15 mL of N,N-dimethylformamide (DMF) and 15 mL of triethylamine (NEt ₃ ). Pd(PPh ₃ ) ₄ , CuI, N,N-dimethylformamide (DMF) and triethylamine (NEt 3 ) are mixed to obtain a mixed solution, and the weighed 2,5-dibromoterephthalaldehyde and 1,3,5-tris(4-ethynylphenyl) are added to the mixed solution to obtain a reaction mixture.

The reaction mixture was replaced with nitrogen for 15 min to form an oxygen-free environment. The reaction mixture was refluxed at 90° C. for 12 hours and 120° C. for 48 hours in an inert atmosphere of nitrogen, then cooled to room temperature, the solid product was filtered and washed with chloroform, acetonitrile, DMF and methanol in sequence to obtain a crude PAF-CHO product.

The crude PAF-CHO product was extracted with methanol for 48 hours to purify the product, and then vacuum dried at 80°C for 24 hours to obtain PAF-CHO.

S2: 1 mL of diethylenetriamine and 20 mL of methanol solution were weighed and mixed to obtain a mixed solution 1. 0.200 g of PAF-CHO prepared according to the above steps was weighed and added to the mixed solution 1 to obtain a mixed solution 2. Under anaerobic conditions (N ₂ ), the mixed solution 2 was refluxed at 80° C. for 15 hours to obtain a mixture. The obtained mixture was cooled to room temperature and reduced with excess sodium borohydride (NaBH ₄ ) (about 1.00 g).

After vigorous stirring at room temperature for 10 hours, the mixture was filtered to obtain a crude PAF-NH ₂ product, which was washed with methanol and water in _sequence and then dried under vacuum at 120° C. for 24 hours to obtain PAF-NH ₂ .

Embodiments 2 to 12

The structural formulas of the aminated porous aromatic skeleton compounds in Examples 2 to 12 are detailed in the above content. The preparation steps are the same as those in Example 1, except for the following process conditions, which are specifically shown in Tables 1.1 and 1.2.

Table 1.1

Table 1.2

Comparative Examples 1 to 5

The preparation steps of the aminated porous aromatic skeleton compounds of Comparative Examples 1 to 5 are the same as those of Example 1, except for the following process conditions, as shown in Table 2.

Table 2

Comparative Example 6

A PAF-CHO material and a preparation method thereof,

The synthetic route is as follows:

The specific steps include:

0.263 g (0.90 mmol) of 2,5-dibromoterephthalaldehyde, 0.227 g (0.60 mmol) of 1,3,5-tris(4-ethynylphenyl)benzene, 0.150 g (0.21 mmol) of Pd(PPh ₃ ) ₄ , 0.050 g (0.26 mmol) of CuI, and 15 mL of N,N-dimethylformamide (DMF) and 15 mL of triethylamine (NEt ₃ ) were weighed respectively. Pd(PPh ₃ ) ₄ , CuI, N,N-dimethylformamide (DMF) and triethylamine (NEt ₃ ) were mixed to obtain a mixed solution, and the weighed 2,5-dibromoterephthalaldehyde and 1,3,5-tris(4-ethynylphenyl) were added to the mixed solution to obtain a reaction mixture. The air in the reaction mixture was replaced with nitrogen for 15 minutes to form an oxygen-free environment. The reaction mixture was refluxed at 90°C for 12 hours and 120°C for 48 hours in an inert atmosphere of nitrogen, then cooled to room temperature, the solid product was filtered and washed with chloroform, acetonitrile, DMF and methanol in sequence to obtain a crude PAF-CHO product. The crude PAF-CHO product was purified by Soxhlet extraction with methanol for 48 hours, and vacuum dried at 80°C for 24 hours to obtain PAF-CHO.

The test results of the composite material prepared by the present invention are analyzed as follows:

(1) Compound structure testing

As shown in Figure 1(a), the alkynyl CH stretching vibration peak at 3267cm ^-1 in 1,3,5-tri(4-ethynylphenyl)benzene and the C-Br stretching vibration peak at 426cm ^-1 in 2,5-dibromoterephthalaldehyde disappeared in PAF-CHO, and a new weak peak appeared at 2201cm ^-1 , which is -C≡C- stretching vibration, indicating that the Sonogashira-Hagihara reaction was completely converted. After the reductive amination of PAF-CHO, the aldehyde vibration peak at 1687cm ^-1 completely disappeared, and new strong NH (3400cm ^-1 ) and CN (1286cm ^-1 ) absorption peaks appeared, proving that the reductive amination was successful.

At the same time, in the solid-state ¹³ C NMR spectrum of PAF-NH ₂ (Figure 2(a)), after reduction and amination with EDTA (ethylenediaminetetraacetic acid), the characteristic peak of the aldehyde carbon at 189 ppm disappeared, while new peaks appeared at 40 and 49 ppm, corresponding to -NH-C- and -NH ₂ -C-, respectively. The solid-state ¹³ C nuclear magnetic resonance spectrum is consistent with the Fourier transform infrared spectroscopy data, which can further confirm the formation of PAF-NH ₂ .

XPS technology can be used to analyze changes in sample surface elements and functional groups, so to a certain extent, the success of the modification can be determined from the changes in element binding energy in the XPS spectrum. Figure 2(b) is the full XPS spectrum of PAF-NH2 prepared in Example 1 and PAF-CHO prepared in Comparative Example 6. In comparison, the PAF- _NH2 material obtained after amination has a new N characteristic peak, while PAF- _NH2 still has an O peak, which may come from water molecules adsorbed on the surface of the material or _CO2 in the air. The XPS results also prove that EDTA has been successfully modified to the pore surface of the porous polymer material, and this result is mutually confirmed by infrared spectroscopy and ^13C solid nuclear magnetic resonance.

(2) Analysis of compound porous structure

The surface structure of the material was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), as shown in Figure 3, wherein Figures 3(a) and 3(b) are scanning electron microscope images of PAF-CHO prepared in Comparative Example 6; Figures 3(c) and 3(d) are scanning electron microscope images of PAF-NH2 prepared in Example 1; Figure 3(e) is a transmission electron microscope image of PAF-CHO prepared in Comparative Example 6; and Figure 3(f) is a transmission electron microscope image of PAF-NH2 prepared in Example 1. It can be seen from Figures 3(a) and 3(b) that the morphology of PAF-CHO is a three-dimensional (3D) porous structure in which uniform nanowires are intertwined. Furthermore, Figures 3(c) and 3(d) show that the pore structure morphology of PAF- _NH2 after amination has not changed much. The porous structure of all materials can also be observed from the TEM images in Figures 3(e) and 3(f), and both materials show a cross-shaped nanorod morphology with a cross-sectional diameter of about 100 nm. The 3D porous structure of these materials is beneficial for the mass transfer of PFAS and water in adsorption, and the results are consistent with those obtained with SEM.

(3) Adsorption kinetics test

0.010g of adsorbent material was added to a 50mL polypropylene centrifuge tube containing 0.040L of 250mg·L ^-1 PFAS solution, and adsorbed by shaking at room temperature. 0.5mL of the solution was taken at regular intervals and filtered. The filtrate was measured for the concentration after adsorption by HPLC with a conductivity detector. The adsorption rate in water was calculated by the following formula:

η%=(c ₀ -c _t )/c ₀ ×100%

Wherein, c _t and c ₀ are the concentrations of PFAS before and after adsorption, respectively (mmol·L ^-1 ).

As shown in Figure 4, it is the adsorption kinetic curve of PFAS by the amino porous aromatic skeleton compound PAF- _NH2 in Example 1 of the present invention. According to the curve changes, the adsorption rates of PAF- _NH2 on five common PFAS are as follows: PFOS>PFOA>PFHxS>PFBS>GenX. Among them, GenX reaches the adsorption equilibrium the fastest, which takes about 5 minutes; PFOS reaches the adsorption equilibrium the slowest, which takes about 50 minutes. It can be seen that the adsorption equilibrium of PAF- _NH2 on five common PFAS (PFOS, PFOA, PFHxS, PFBS, GenX) can be reached within 5 to 50 minutes.

As shown in Table 3 below, it is the adsorption equilibrium time table of various types of adsorbent materials for adsorbing PFAS. According to the data in the table, the adsorption equilibrium time of other types of adsorbent materials is greater than 1 hour. However, the PAF- _NH2 generated by the present invention can achieve adsorption equilibrium of five common PFAS (PFOS, PFOA, PFHxS, PFBS, GenX) within 50 minutes, indicating that the adsorption rate of PAF- _NH2 for five common PFAS (PFOS, PFOA, PFHxS, PFBS, GenX) is relatively fast.

In addition, observing the ordinate of the adsorption kinetics curve in Figure 4, it can be seen that the adsorption rate of PAF- _NH2 for PFBS and GenX can reach nearly 50%, the adsorption rate for PFHxS can reach about 70%, the adsorption rate for PFOA can reach about 80%, and the adsorption rate for PFOS can reach about 95%, indicating that PAF- _NH2 has a high degree of adsorption for five common PFAS (PFOS, PFOA, PFHxS, PFBS, GenX).

As shown in Table 3, compared with other types of adsorbent materials, the adsorbent material PAF-NH ₂ provided by the present invention can achieve the fastest adsorption equilibrium time and at the same time ensure strong adsorption capacity in terms of adsorption amount and adsorption equilibrium time. In summary, the adsorption effect of PAF-NH ₂ on five common PFAS (PFOS, PFOA, PFHxS, PFBS, GenX) is generally good.

Table 3

(4) Adsorption isotherm test

Accurately measure 25 mL of PFAS solution with known initial concentration (50-450 mg·L ^-1 ) in a 50 mL polypropylene centrifuge tube, adjust the pH to 3, add 0.005 g of adsorbent material, shake at room temperature for sufficient adsorption time (>2 h), filter, and detect PFAS concentration. Calculate the adsorption amount using the following formula:

Where _qt is the adsorption amount (mmol·g ^-1 ); _ct and _c0 are the concentrations of PFAS before and after adsorption (mmol·L ^-1 ); V is the volume of the solution (L); and m is the mass of the adsorbent material (g). The method for calculating the adsorption amount in subsequent tests is the same as this.

As shown in Figure 5, the adsorption isotherms of the amino porous aromatic skeleton compound PAF- _NH2 in Example 1 of the present invention for five common PFAS (PFOS, PFOA, PFHxS, PFBS, GenX). Langmuir and Freundlich simulations were performed on the adsorption isotherms, and the adsorption of PAF- _NH2 on PFOS, PFOA, and PFHxS, three PFAS with greater hydrophobicity, was more consistent with the Freundlich model, indicating that its adsorption type was multilayer adsorption, and the experimentally measured adsorption amounts were 2.80, 2.15, and 1.62 mmol·g ^-1, respectively, and the maximum saturated adsorption had not yet been reached. The adsorption of PFBS and GenX with poor hydrophobicity was more consistent with the Langmuir model, indicating that the adsorption type of PAF- _NH2 on these two PFAS was monolayer adsorption, and the maximum saturated adsorption amounts were 1.26 and 1.53 mmol·g ^-1, respectively.

(5) Test on the effect of pH on adsorption efficiency

Taking PFOS as an example, 0.005 g of PAF-NH ₂ adsorbent material was added to a 50 mL polypropylene centrifuge tube containing 0.025 L of 250 mg·L ^-1 PFOS solution, and adsorbed for a sufficient time at room temperature with shaking, filtered, and the filtrate was measured by HPLC with a conductivity detector to determine the concentration after adsorption. The adsorption amount was calculated using the above formula.

The results are shown in Figure 6(a), and the adsorption of PFOS by PAF-NH ₂ is 2.15, 1.49, 1.09, 0.84, and 0.73 mmol·g ^-1 at pH = 3, 5, 7, 9, and 11, respectively. It can be seen that as the pH value increases, the adsorption of PFOS by PAF-NH ₂ gradually decreases, but the adsorption amount is still as high as 0.73 mmol·g ^-1 , indicating that acidic conditions are more conducive to the adsorption of PFAS and the adsorption of PFOS by PAF-NH ₂ is the largest at pH = 3.

(6) Regeneration test

a. Adsorption: Add 0.010 g PAF-NH ₂ to 50 mL of 250 mg·L ^-1 PFOS aqueous solution at pH 3, shake at room temperature for sufficient adsorption time (>2 h), centrifuge to separate the adsorbent material, filter a small amount of the solution, measure the concentration of the filtrate after adsorption by HPLC with a conductivity detector, and calculate the adsorption amount.

b. Desorption: The centrifuged PAF-NH ₂ was added to 30 mL of a mixed solvent of 1% NaOH solution and CH ₃ OH in a volume ratio of 3:7 and desorbed by shaking for 2 hours. The adsorbent material was vacuum dried at 120°C for 24 hours and the adsorption and desorption steps were repeated. As shown in Figure 6(b), the adsorption amount of PAF-NH ₂ remained basically unchanged after five cycles, indicating that PAF-NH ₂ has good regeneration and can be used multiple times in practical applications to recycle the adsorption material resources and be environmentally friendly.

(7) Test on the influence of different interfering substances on adsorption efficiency

0.005 g PAF-NH ₂ was added to a 50 mL polypropylene centrifuge tube containing 0.025 L 250 mg·L ^-1 PFOS solution and different concentrations of a single interfering substance (KCl or Na ₂ SO ₄ or humic acid). The solution pH was maintained at 7, and adsorption was performed at room temperature for a sufficient time with shaking. The filtrate was filtered and the concentration after adsorption was measured by HPLC with a conductivity detector, and the adsorption amount was calculated by the above formula. As shown in Figure 7(a), when humic acid is not added, the adsorption amount of PFOS by PAF- _NH2 is 1.07mmol·g ^-1 . In the presence of a higher concentration of humic acid (concentration of 70mg·L ^-1 ), the adsorption amount of PFOS by PAF- _NH2 is 0.76mmol·g ^-1 , which can still reach more than 70% of the initial value. In addition, as shown in Figure 7(b), in the presence of ^{a higher concentration of SO42-} _or ^Cl- (concentration of 5mmol·L ^-1 ), the adsorption amount of PFOS by PAF- _NH2 is 0.85mmol·g ^-1 and 0.89mmol·g ^-1 , respectively, which can still reach more than 85% of the initial value. This shows that PAF- _NH2 has a good selective adsorption effect on PFOS and is less affected by interfering substances.

(8) Comparison of adsorption properties of the products prepared in Example 1 and Comparative Examples 1 to 3

Comparative Examples 1 to 3 test the adsorption properties of products generated under different conditions by changing the amount of polyamine added in step 2 of Example 1.

Taking PFOS as a representative, 0.01 g of PAF-NH ₂ prepared in Example 1 was added to a 50 mL polypropylene centrifuge tube containing 0.04 L of 250 mg·L ^-1 PFOS solution, the solution pH was kept at 3, and the adsorption was carried out for a sufficient time at room temperature under oscillation, filtered, and the filtrate was measured by HPLC with a conductivity detector to obtain the concentration after adsorption. The adsorption amount was calculated by the above formula. Similarly, the adsorption amount of the products in Comparative Examples 1 to 3 was tested and calculated. The results are shown in Figure 8. For ease of analysis, the products obtained in Comparative Examples 1 to 3 are marked as PAF-NH ₂ -1, PAF-NH ₂ -2 and PAF-NH ₂ -3, respectively.

As shown in Figure 8, when no diethylenetriamine is added in step 2, the adsorption amount of PAF- _NH2-1 is 0.91mmol·g ^-1 ; when the diethylenetriamine in step 2 is less (20% relative to the aldehyde group), the adsorption amount of PAF- _NH2-2 is 1.24mmol·g ^-1 ; when the diethylenetriamine in step 2 is half of that in Example 1 (50% relative to the aldehyde group), the adsorption amount of PAF- _NH2-3 is 1.62mmol·g ^-1 ; and when excessive diethylenetriamine is added in step 2 (i.e., the experimental conditions in Example 1), the adsorption amount of PAF- _NH2 is 2.19mmol·g ^-1 . It can be seen that the different degrees of post-synthesis modification of the amino group on the intermediate product PAF-CHO will also affect the adsorption effect of the final product on pollutants.

The adsorption results of the products prepared in Example 1 and Comparative Examples 1 to 3 are shown in Table 4.

Table 4

(9) Comparison of adsorption properties of the products prepared in Example 1 and Comparative Examples 4 to 5

Comparative Examples 4 to 5 tested the adsorption properties of products generated under different conditions by changing the reaction conditions in step 2 of Example 1.

Taking PFOS as a representative, 0.01g of PAF- _NH2 prepared in Example 1 was added to a 50mL polypropylene centrifuge tube containing 0.04L 250mg·L ^-1 PFOS solution, the solution pH was kept at 3, and the adsorption was carried out for a sufficient time under room temperature oscillation, filtered, and the filtrate was measured by HPLC with a conductivity detector to obtain the concentration after adsorption. The adsorption amount was calculated by the above formula. Similarly, the adsorption amount of the products in Comparative Examples 4 to 5 was tested and calculated. The results are shown in Table 5.

Table 5

According to Table 5, if the temperature or heating time in the condensation reaction of step S2 cannot reach certain conditions, the adsorption performance of the generated product is also poor. It can be concluded that if the degree of post-synthesis modification of the amino group on the intermediate product PAF-CHO is low, the final product's adsorption capacity for pollutants is also low.

(10) Comparison of adsorption performance of PAF- _NH2 in Example 1 and PAF-CHO in Comparative Example 6

a. Comparison of the adsorption of PFAS in water by PAF- _NH2 and PAF-CHO

0.01gPAF- _NH2 was added to 50mL polypropylene centrifuge tubes containing 0.04L 250mg·L ^-1 solutions of five common PFAS (PFOS, PFOA, PFHxS, PFBS, GenX), and the pH of the solution was maintained at 3. The adsorption was carried out under oscillation at room temperature for a sufficient time, and the filtrate was filtered. The concentration after adsorption was measured by HPLC with a conductivity detector. Similarly, 0.01gPAF-CHO was added to 50mL polypropylene centrifuge tubes containing 0.04L 250mg·L ^-1 solutions of five common PFAS (PFOS, PFOA, PFHxS, PFBS, GenX), and the pH of the solution was maintained at 3. The adsorption was carried out under oscillation at room temperature for a sufficient time, and the filtrate was filtered. The concentration after adsorption was measured by HPLC with a conductivity detector. The adsorption amount was calculated by the above formula.

As shown in Figure 9(a), the adsorption capacities of PAF- _NH2 for five common PFAS (PFOS, PFOA, PFHxS, PFBS, GenX) were 2.19mmol·g ^-1 , 1.62mmol·g ^-1 , 1.2mmol·g ^-1 , 2.08mmol·g ^-1 and 1.53mmol·g ^-1 , respectively. The adsorption capacities of PAF-CHO for five common PFAS (PFOS, PFOA, PFHxS, PFBS, GenX) were 0.91mmol·g ^-1 , 0.51mmol·g ^-1 , 0.42mmol·g ^-1 , 0.76mmol·g ^-1 and 0.18mmol·g ^-1 , respectively. Compared with PAF-CHO, the adsorption of five common PFAS (PFOS, PFOA, PFHxS, PFBS, GenX) by ₂ was increased by 141%, 218%, 186%, 174% and 750% respectively. It can be seen that the introduction of amino groups on porous aromatic skeleton materials can greatly increase the adsorption capacity of adsorbent materials for pollutants.

b. Comparison of adsorption kinetics of PFOS in water by PAF- _NH2 and PAF-CHO

Taking PFOS as an example, the adsorption kinetics of PFOS in water by PAF-NH ₂ and PAF-CHO in a were tested, and the test results are shown in Figure 9(b). Analysis of Figure 9(b) shows that the adsorption of PFOS by PAF-NH ₂ can reach adsorption equilibrium within about 50 minutes, and the adsorption amount can reach about 95%. However, in contrast, the adsorption of PFOS by PAF-CHO can reach adsorption equilibrium within about 600 minutes, and the adsorption amount is only about 50%. It can be seen that the adsorption effect of PAF-NH ₂ far exceeds that of PAF-CHO, and it has a more obvious adsorption performance advantage, and can be widely used in the environmental field.

Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims (11)

1. An aminated porous aromatic skeleton compound, characterized in that it comprises any one of the following structural formulas:

Among them, R stands for

any of the. 2. a preparation method of aminated porous aromatic skeleton compound as claimed in claim 1, is characterized in that, comprises the following steps: S1. Mix 2,5-dibromophenylaldehyde, terminal alkyne compound, palladium catalyst, and cuprous iodide in N,N-dimethylformamide and triethylamine, and perform Sonogashira under anaerobic conditions -Hagihara coupling reaction to obtain the formylated porous aromatic skeleton compound PAF-CHO; S2. Disperse the formylated porous aromatic skeleton compound PAF-CHO and excess polyamines in step S1 in an organic solvent, and obtain a Schiff base intermediate through condensation reaction under anaerobic conditions, and then add a reducing agent to carry out Reduction reaction, filtering, washing and drying to obtain the aminated porous aromatic skeleton compound PAF-NH ₂ ; The terminal alkynyl compound described in step S1 is 1,3,5-tris(4-ethynylphenyl)benzene, 2,4,6-tris(4-ethynylphenyl)-1,3,5- Triazine, tris(4-ethynylphenyl)amine, tetrakis(4-ethynylphenyl)methane, tetrakis(4-ethynylphenyl)ethylene or 1,3,5,7-tetrakis(4-ethynylphenyl) ) Any of the adamantanes. 3. the preparation method of aminated porous aromatic skeleton compound according to claim 2, is characterized in that, 2,5-dibromophenylaldehyde described in step S1 is 2,5-dibromoterephthalaldehyde or Any of 2,5-dibromobenzaldehyde. 4. the preparation method of aminated porous aromatic skeleton compound according to claim 2, is characterized in that, described formylated porous aromatic skeleton compound PAF-CHO comprises any one in the following structural formula:

5. the preparation method of aminated porous aromatic skeleton compound according to claim 2, is characterized in that, bromine and alkynyl in the 2,5-dibromophenylaldehyde described in step S1, terminal alkynyl compound The ratio of the amount of substances is 1:1. 6. the preparation method of aminated porous aromatic skeleton compound according to claim 2, is characterized in that, described in step S1, 2,5-dibromophenylaldehyde, described palladium catalyst and described cuprous iodide The ratio of the amount of the substance is 1:(0.1～1):(0.1～1); the volume ratio of the N,N-dimethylformamide and the triethylamine is 1:(0.1～1); The amount and volume ratio of the 2,5-dibromophenylaldehyde to the N,N-dimethylformamide is 1 mmol: (15-20) ml; the palladium catalyst is Pd(PPh ₃ ) ₄ or Pd(PPh ₃ ) ₂ Cl ₂ . 7 . The preparation method of aminated porous aromatic skeleton compound according to claim 2 , characterized in that, the reaction condition of the Sonogashira-Hagihara coupling reaction is to heat and reflux at 80-120° C. for 1-3 days. 8. The method for preparing an aminated porous aromatic skeleton compound according to claim 2, wherein the polyamine described in step S2 is any one of ethylenediamine, propylenediamine or diethylenetriamine; The organic solvent is any one of methanol, ethanol, N,N-dimethylformamide or dimethyl sulfoxide; the reducing agent is sodium borohydride, sodium cyanoborohydride or triacetyl borohydride any of sodium. 9 . The preparation method of aminated porous aromatic skeleton compound according to claim 2 , characterized in that, the reaction condition of the condensation reaction is to heat and reflux at 80-120° C. for 12-24 hours. 10. The application of the aminated porous aromatic skeleton compound according to claim 1 as an adsorption material in the adsorption of PFAS pollutants in water. 11. A method for the PFAS pollutants of the aminated porous aromatic skeleton compound as claimed in claim 1 as adsorption material adsorption and desorption, it is characterized in that, comprising the following steps: The aminated porous aromatic skeleton compound is added to the solution to be adsorbed, and the PFAS pollutants are adsorbed by shaking for a sufficient time; after the adsorption is completed, the adsorbed material is subjected to centrifugation and desorption treatment, and then dried.

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