PAM / COF composite material for treating dye wastewater and preparation method thereof

Abstract

The application belongs to the technical field of wastewater treatment, and specifically relates to a PAM / COF composite material for treating dye wastewater and a preparation method thereof. First, p-toluenesulfonic acid monohydrate and triformylphloroglucin are dissolved in deionized water to obtain a mixed solution A; acrylamide, N,N-methylenebisacrylamide, polyvinylpyrrolidone, PEG-200 polyethylene glycol and Tween 20 are ultrasonically dispersed in deionized water to obtain an aqueous phase; benzene, n-heptane and cyclohexane are mixed according to a volume ratio of 1:1:2.5 to obtain an oil phase; the PAM / COF composite material is prepared by adopting an emulsion polymerization method, PAM powder is added into the mixed solution A, then diaminoanthraquinone is added, and after mixing, heating reaction is carried out, and then drying is carried out. The organic framework (COF) material and polyacrylamide (PAM) are prepared into the PAM / COF composite material, and the problems of low mechanical strength, poor dispersibility, easy agglomeration, low adsorption efficiency, poor regeneration performance, poor treatment effect on complex dye wastewater and the like of the COF material are overcome.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically a PAM / COF composite material for treating dye wastewater and its preparation method. Background Technology

[0002] The rapid development of the textile industry has generated a large amount of dye wastewater. This wastewater is complex, containing organic matter and harmful substances with high toxicity. Water bodies cannot degrade these pollutants quickly through simple self-purification. This not only harms aquatic bodies and aquatic life but also accumulates along the food chain, ultimately threatening human health. Commonly used methods for treating dye wastewater include biological methods, membrane separation, photocatalysis, electrochemical methods, and adsorption. Among these, adsorption is widely used due to its advantages of simple operation, high efficiency, and low cost.

[0003] In recent years, covalent organic frameworks (COFs), as a novel type of porous material, have attracted researchers' attention due to their unique tunable structure, large specific surface area, and excellent adsorption performance. COFs can achieve efficient adsorption by engaging in physical or chemical interactions with dye molecules through their ordered pore structure. However, COFs also have certain limitations in practical applications, such as low mechanical strength, poor dispersibility, and tendency to aggregate, which restricts their use in water treatment. Summary of the Invention

[0004] The purpose of this invention is to provide a PAM / COF composite material for treating dye wastewater and its preparation method, aiming to overcome the problems of low mechanical strength, poor dispersibility, easy agglomeration, low adsorption efficiency, poor regeneration performance, and poor treatment effect on dye wastewater of existing covalent organic framework (COF) materials.

[0005] This invention is specifically achieved through the following technical solution: a method for preparing a PAM / COF composite material for treating dye wastewater, according to this invention, includes the following steps:

[0006] (1) Weigh a certain amount of p-toluenesulfonic acid monohydrate and trialdehyde phloroglucinol, add them to deionized water, and sonicate for 10-20 min to obtain mixed solution A;

[0007] (2) Take another certain volume of deionized water and add acrylamide, N,N-methylenebisacrylamide, polyvinylpyrrolidone, PEG-200 polyethylene glycol and Tween 20 to it in sequence. Disperse by ultrasonication until completely and evenly dispersed to obtain an aqueous phase.

[0008] (3) Mix benzene, n-heptane and cyclohexane in a volume ratio of 1:1:2.5 and stir thoroughly to obtain the oil phase;

[0009] (4) According to the volume ratio of water phase to oil phase of 2:1, take a certain amount of water phase prepared in step (2) and oil phase prepared in step (3), add the oil phase to the water phase while stirring. After the oil phase is completely added, continue stirring until a milky white oil-in-water emulsion is formed. Add ammonium persulfate to the oil-in-water emulsion, stir evenly, and then transfer the mixture to a reaction vessel with a polytetrafluoroethylene liner. Then, add N,N,N',N'-tetramethylethylenediamine to the reaction vessel with a polytetrafluoroethylene liner and stir quickly evenly. Then, seal the reaction vessel with a polytetrafluoroethylene liner and place it in an oven at 55°C for 8~20 min. After the reaction is completed, wash the obtained product three times with methanol by centrifugation, and then dry the centrifuged product in a vacuum oven at 50°C for 8~12 h to obtain porous polyacrylamide powder, which is denoted as PAM powder.

[0010] (5) Add the prepared PAM powder to the mixed solution A in step (1) and stir evenly to obtain mixed solution B; add diaminoanthraquinone to mixed solution B, mix and stir evenly, and then transfer to a polytetrafluoroethylene-lined reactor. Heat the polytetrafluoroethylene-lined reactor at 120°C for 18 h to allow it to react fully. After the reaction is completed, let the product cool naturally to room temperature and then perform vacuum drying to obtain porous polyacrylamide / COF composite material, which is denoted as PAM / COF composite material.

[0011] In the aforementioned method for preparing porous polyacrylamide / COF composite material for treating dye wastewater, in step (1), the mass ratio of p-toluenesulfonic acid monohydrate to trialdehyde phloroglucinol is 22:5, and the ratio of the volume of deionized water to the total mass of p-toluenesulfonic acid monohydrate and trialdehyde phloroglucinol is 8 mL: 27 mg.

[0012] In the aforementioned method for preparing porous polyacrylamide / COF composite material for treating dye wastewater, in step (2), the mass ratio of acrylamide, N,N-methylenebisacrylamide, polyvinylpyrrolidone, PEG-200 polyethylene glycol, and Tween 20 is 13:1:1:1.2:8; and the volume ratio of deionized water in step (2) to that in step (1) is 1:1.

[0013] In the aforementioned method for preparing porous polyacrylamide / COF composite material for treating dye wastewater, the stirring speed in step (4) is 1500 rpm.

[0014] In the aforementioned method for preparing porous polyacrylamide / COF composite material for treating dye wastewater, the concentration of ammonium persulfate in the oil-in-water emulsion in step (4) is 1.25 mg / mL, and the volume ratio of N,N,N',N'-tetramethylethylenediamine to the volume of the oil-in-water emulsion is 1:120.

[0015] In the aforementioned method for preparing porous polyacrylamide / COF composite material for treating dye wastewater, the mass ratio of diaminoanthraquinone in step (5) to that in step (1) is 3:5.

[0016] In the aforementioned method for preparing porous polyacrylamide / COF composite material for treating dye wastewater, the PAM powder prepared in step (4) is a near-spherical particle with a particle size of 300~600 μm; in the PAM / COF composite material prepared in step (5), the COF material is attached to the pore structure of the PAM material, and the particle size of the COF material is 50~200 nm.

[0017] The present invention also provides a PAM / COF composite material obtained by the above preparation method and its application in the treatment of dye wastewater. The PAM / COF composite material is added to the dye wastewater and shaken for adsorption. After 90-120 min, the adsorption reaches equilibrium.

[0018] Preferably, the pH of the dye wastewater is >7, its concentration is 30~50 mg / L, and the mass ratio of the added PAM / COF composite material to the volume of the dye wastewater is 3 mg : 10 mL.

[0019] Furthermore, the dyes mentioned include, but are not limited to, methyl orange, Congo red, methylene blue, and crystal violet.

[0020] Compared with existing technologies, this invention has significant advantages and beneficial effects. Through the above technical solution, this invention achieves considerable technological advancement and practicality, and has broad application value, possessing at least the following advantages:

[0021] (1) This invention utilizes emulsion polymerization to prepare porous polyacrylamide (PAM) materials. Polyacrylamide (PAM) is a polymer material with good adsorption capacity. Its structure contains a large number of functional groups, which can strongly interact with pollutants in water, thereby effectively removing pollutants from the water. Preparing PAM / COF composite materials with organic framework (COF) materials and polyacrylamide (PAM) can overcome the defects of poor mechanical properties of COF materials and enhance the overall adsorption performance of composite materials. In particular, the near-spherical porous structure of polyacrylamide not only improves the mechanical strength of the material, but also the COF material attached to the pore structure of porous polyacrylamide (PAM) helps to reduce or avoid the aggregation of COF materials. Thus, the PAM / COF composite material exhibits good structural stability during long-term use, avoiding the problems of easy aggregation and poor dispersibility of traditional COF materials in the aquatic environment. In addition, the spherical porous structure of PAM enhances the compressive strength of the composite material, so that it will not undergo significant breakage or deformation during long-term wastewater treatment, thus extending the service life of the composite material.

[0022] (2) The PAM / COF composite material prepared by the present invention has a large specific surface area and abundant pore structure, which can significantly improve the adsorption efficiency and has excellent chemical and mechanical stability. It has a significant adsorption effect on methyl orange dye wastewater. The PAM / COF composite material can maintain excellent adsorption capacity in a wide pH range (e.g., from acidic to neutral) and at different temperatures (e.g., from room temperature to high temperature). It is less affected by environmental conditions, which improves its applicability in practical applications.

[0023] (3) The PAM / COF composite material of the present invention not only exhibits excellent adsorption effect on methyl orange dye wastewater, but also shows good adsorption performance on other common dyes (such as methylene blue, Congo red, etc.). Therefore, the PAM / COF composite material prepared by the present invention is suitable for treating various types of dye wastewater and has broad application prospects in textile, printing and dyeing and other industrial fields.

[0024] (4) The PAM / COF composite material prepared by this invention has good mechanical strength and chemical stability. It can be regenerated through simple alkaline washing, making the regeneration operation convenient, reducing material consumption and costs, and improving economic efficiency. It maintains good adsorption performance during multiple regeneration cycles. The PAM / COF composite material does not experience significant breakage or deformation during these cycles, indicating that it has good stability and a long service life, thus effectively reducing the operating costs of industrial wastewater treatment. Simultaneously, the high adsorption capacity of the PAM / COF composite material can accelerate wastewater treatment speed, improve treatment efficiency, and enhance the economic benefits of the entire wastewater treatment process.

[0025] (5) The preparation method of the present invention is simple, the raw material cost is low, the preparation conditions are mild and easy to operate. The prepared PAM / COF composite material has both high durability and regeneration ability, which can reduce the overall production and use cost of adsorbent materials and improve production efficiency and economic benefits. Attached Figure Description

[0026] Figure 1 These are scanning electron microscope images of the PAM powder prepared in Example 1 at different magnifications.

[0027] Figure 2 This is a scanning electron microscope image of the PAM / COF composite material prepared in Example 1.

[0028] Figure 3 The curves show the change in adsorption efficiency of PAM material and PAM / COF composite material for methyl orange over adsorption time.

[0029] Figure 4 The curves show the adsorption efficiency of PAM / COF composite material for methyl orange at different temperatures as a function of adsorption time.

[0030] Figure 5 The curves show the adsorption efficiency of the PAM / COF composite material for methyl orange aqueous solutions at different pH values ​​as a function of adsorption time.

[0031] Figure 6 The curves show the change in adsorption efficiency of PAM / COF composite materials for different dyes over adsorption time.

[0032] Figure 7 This is a comparison chart of the adsorption efficiency of PAM / COF composite material for methyl orange aqueous solution under different cycles of adsorption. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] The present invention will be described in detail below with reference to specific embodiments. Unless otherwise specified, all conditions in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Raw materials and reagents whose manufacturers are not specified are all commercially available products.

[0035] Example 1

[0036] (1) Weigh 220 mg of p-toluenesulfonic acid monohydrate and 50 mg of trialdehyde phloroglucinol, add them to 80 mL of deionized water, and sonicate for 10 min to obtain mixed solution A.

[0037] (2) Take another 80 mL of deionized water and add 13 g of acrylamide, 1 g of N,N-methylenebisacrylamide, 1 g of polyvinylpyrrolidone, 1.2 g of PEG-200 polyethylene glycol and 8 g of Tween 20 to it in sequence. Disperse by ultrasonication until completely and evenly dispersed to obtain an aqueous phase.

[0038] (3) Mix 10 mL benzene, 10 mL n-heptane and 25 mL cyclohexane (the volume ratio of benzene, n-heptane and cyclohexane is 1:1:2.5) and stir thoroughly to obtain the oil phase.

[0039] (4) Stir the aqueous phase from step (2) at 1500 rpm while adding 40 mL of the oil phase prepared in step (3). After the oil phase is completely added, continue stirring at 1500 rpm until a milky white oil-in-water emulsion is formed, with a final volume ratio of aqueous phase to oil phase of 2:1. Then, add 150 mg of ammonium persulfate to the obtained oil-in-water emulsion, stir evenly, and transfer the mixture to a polytetrafluoroethylene-lined reactor. Add 1 mL of N,N,N',N'-tetramethylethylenediamine to the polytetrafluoroethylene-lined reactor and stir quickly and evenly. Then, seal the polytetrafluoroethylene-lined reactor and place it in an oven at 55°C for 8 min. After the reaction, wash the obtained product three times with methanol by centrifugation, and then dry the centrifuged product in a vacuum oven at 50°C for 8 h to obtain porous polyacrylamide powder, denoted as PAM powder.

[0040] (5) The prepared PAM powder was added to the mixed solution A in step (1) and stirred until homogeneous to obtain mixed solution B. 30 mg of diaminoanthraquinone was added to mixed solution B, and after mixing and stirring until homogeneous, it was transferred to a polytetrafluoroethylene-lined reactor. The polytetrafluoroethylene-lined reactor was placed in an oven and heated at 120°C for 18 h to allow it to react fully. After the reaction was completed, the product was naturally cooled to room temperature and then vacuum dried at 65°C for 18 h. After drying, a porous polyacrylamide / COF composite material was obtained, denoted as PAM / COF composite material.

[0041] The surface morphology of the PAM powder and PAM / COF composite material prepared in Example 1 was observed using a scanning electron microscope, as follows: Figure 1 and Figure 2 As shown.

[0042] Figure 1Image (a) is a scanning electron microscope image of the PAM powder prepared in Example 1 at 800x magnification. Figure 1 Image (b) is a scanning electron microscope image of the PAM powder prepared in Example 1 at 2500x magnification. Figure 1 In (a), it can be seen that the PAM powder consists of nearly spherical particles with a particle size of approximately 300–600 μm. Figure 1 In (b), it can be observed that the surface of PAM particles has a non-uniformly sized pore structure, including nano-sized pores and micro-sized pores. Therefore, PAM has a porous structure.

[0043] Figure 2 This is a scanning electron microscope image of the PAM / COF composite material prepared in Example 1. It can be clearly seen that the COF material is attached to the porous structure of the polyacrylamide (PAM), and the particle size of the COF material is approximately 50~200 nm.

[0044] Adsorption effect test of PAM / COF composite material on dye wastewater:

[0045] (I) Comparison of adsorption effects of PAM powder and PAM / COF composite material

[0046] Weigh 15 mg of the PAM powder prepared in step (4) of Example 1 and the PAM / COF composite material prepared in step (5) respectively, and place them in two beakers. Add 50 mL of methyl orange aqueous solution with a concentration of 30 mg / L to the two beakers. Place them in a constant temperature shaker and shake for adsorption at room temperature. Take a certain amount of solution at regular intervals, centrifuge, and take the supernatant to test the absorbance with a TU-1901 UV-Vis spectrophotometer. Substitute the absorbance into the standard curve equation of methyl orange absorbance as a function of concentration to obtain the concentration of methyl orange corresponding to the corresponding absorbance. Calculate the adsorption efficiency according to the following formula (1):

[0047] q t =(( c 0 - c t ) / c 0 )×100% (1)

[0048] In the formula, q t This represents the adsorption efficiency. c 0 represents the initial concentration of the methyl orange aqueous solution, in mg / L; c t The value represents the concentration of the methyl orange aqueous solution at time t, in mg / L.

[0049] Plot a graph with adsorption efficiency on the ordinate and adsorption time on the abscissa, as shown below. Figure 3 As shown, both PAM and PAM / COF composites exhibited rapid adsorption rates within the first 20 minutes. This is due to the high dye concentration in the initial stage, resulting in numerous active sites on the material surface that facilitated rapid adsorption of dye molecules. Throughout the adsorption process, the adsorption efficiency of the PAM / COF composite for methyl orange was significantly higher than that of the PAM material. At 60 minutes, the adsorption efficiency of the PAM / COF composite for methyl orange approached 90%, while that of the PAM material was closer to 70%. This difference is attributed to the addition of COF material, which enhanced the porosity and specific surface area of ​​the PAM / COF composite, providing more adsorption sites for dye molecules. Around 100 minutes, the PAM / COF composite reached adsorption equilibrium, with an adsorption efficiency exceeding 90% for methyl orange. In contrast, the adsorption efficiency of the PAM material was only around 80% within the same timeframe. This indicates that the introduction of COF material significantly improved the adsorption performance and rate of the PAM / COF composite, with the adsorption equilibrium time for methyl orange in the PAM / COF composite being 100–120 minutes.

[0050] (II) Comparison of the adsorption effect of PAM / COF composite material on methyl orange at different temperatures

[0051] 15 mg of PAM / COF composite material was added to 50 mL of methyl orange aqueous solution with a concentration of 30 mg / L. The solution was placed in a constant temperature shaker at 20 °C for adsorption. A certain amount of solution was taken at regular intervals, centrifuged, and the supernatant was used to measure the absorbance of the solution using a TU-1901 UV-Vis spectrophotometer. The absorbance was then substituted into the standard curve equation of methyl orange absorbance versus concentration to obtain the methyl orange concentration corresponding to the absorbance. The adsorption efficiency of PAM / COF composite material for methyl orange at 20 °C was calculated according to the aforementioned formula (1). The adsorption temperature was adjusted to 25 °C, 30 °C, and 40 °C respectively. The adsorption efficiency of PAM / COF composite material for methyl orange at 25 °C, 30 °C, and 40 °C was tested in the same way. The adsorption efficiency was plotted on the ordinate and the adsorption time on the abscissa. Figure 4 As shown, the adsorption performance of PAM / COF composite materials for methyl orange increases with increasing temperature, but the effect is similar between 25℃, 30℃, and 40℃. This indicates that PAM / COF composite materials can effectively adsorb methyl orange at different temperatures, making them particularly suitable for industrial wastewater treatment. Adsorption treatment can be carried out at 25~30℃ to achieve high adsorption efficiency while reducing energy consumption and extending the material's service life.

[0052] (III) Comparison of adsorption effects of PAM / COF composite materials on methyl orange aqueous solutions at different pH values

[0053] Prepare a certain volume of methyl orange aqueous solution with pH values ​​of 3, 5, 7, 9, and 11 (the concentration of methyl orange aqueous solution is 30 mg / L). Take 50 mL of methyl orange aqueous solution with each pH value as the adsorption solution. Add 15 mg of PAM / COF composite material to each adsorption solution and place it in a constant temperature shaker at 30℃ for adsorption. Take a certain amount of solution at regular intervals, centrifuge it, and take the supernatant. Use a TU-1901 UV-Vis spectrophotometer to test the absorbance of the solution. Substitute the absorbance into the standard curve equation of methyl orange absorbance with concentration to obtain the methyl orange concentration corresponding to the corresponding absorbance. Calculate the adsorption efficiency of PAM / COF composite material on methyl orange aqueous solution at different times according to the aforementioned formula (1). Plot the adsorption efficiency as the vertical axis and the adsorption time as the horizontal axis, as shown in the figure. Figure 5 As shown in the figure, the adsorption efficiency of the PAM / COF composite material for methyl orange increases with increasing pH, especially under alkaline conditions. This is because under alkaline conditions, the material surface carries more negative charges, enhancing the electrostatic attraction between the material and methyl orange molecules, thus improving adsorption efficiency. Therefore, in practical applications, adsorption is best performed at pH 7–9 to achieve optimal treatment results and cost-effectiveness.

[0054] (iv) Comparison of adsorption effects of PAM / COF composite materials on aqueous solutions of different dyes

[0055] Prepare 50 mL solutions of methyl orange, Congo red, methylene blue, and crystal violet at a concentration of 30 mg / L, respectively. Add 15 mg of PAM / COF composite material to each dye solution and place them in a constant temperature shaker at 30°C for adsorption. Take a certain amount of solution at regular intervals, centrifuge, and take the supernatant. Measure the absorbance of the solution using a TU-1901 UV-Vis spectrophotometer. Substitute the absorbance into the standard curve equation of methyl orange absorbance versus concentration to obtain the methyl orange concentration corresponding to the corresponding absorbance. Calculate the adsorption efficiency of the PAM / COF composite material for different dye solutions at different times according to the aforementioned formula (1). Plot a graph with adsorption efficiency as the ordinate and adsorption time as the abscissa, as shown below. Figure 6As shown in the figure, the PAM / COF composite material exhibits excellent adsorption performance for various dyes, especially methyl orange and Congo red, with an adsorption efficiency exceeding 90% at 180 min. This is likely attributed to the porous structure of COF and the polar functional groups of PAM, which enable effective interactions with these dye molecules. In contrast, the adsorption efficiency for methylene blue and crystal violet is slightly lower, but still exceeds 85% at 180 min. This demonstrates that the PAM / COF composite material prepared in this invention possesses excellent adsorption performance for various dyes.

[0056] (v) Stability test of PAM / COF composite material for adsorption of methyl orange aqueous solution

[0057] Weigh 15 mg of the PAM / COF composite material prepared in step (5) of Example 1 and place it in a beaker. Add 50 mL of methyl orange aqueous solution with pH=9 and concentration of 30 mg / L to the beaker. Place it in a constant temperature shaker and shake it at room temperature for adsorption. The adsorption time is set to 120 min. After completion, take a certain amount of solution, centrifuge it, and take the supernatant. Use a TU-1901 UV-Vis spectrophotometer to test the absorbance. Substitute the absorbance into the standard curve equation of methyl orange absorbance with concentration to obtain the methyl orange concentration corresponding to the corresponding absorbance. Calculate the adsorption efficiency of PAM / COF composite material for methyl orange according to formula (1). The PAM / COF composite material that had adsorbed methyl orange was added to a 5% sodium hydroxide solution and placed in a constant-temperature shaker at 40°C for 30 min to desorb. After desorption, the material was filtered, and the filtered adsorbent was washed several times with distilled water until the washing solution was neutral. The material was then filtered again, dried in an oven, and reused in the adsorption experiment. This cycle was repeated 5 times, and the adsorption efficiency of the PAM / COF composite material for methyl orange after each adsorption was calculated. A graph was plotted between adsorption efficiency and the number of uses, as shown below. Figure 7 As shown, the adsorption efficiency of the PAM / COF composite material for methyl orange remains stable at over 80% after five cycles of use. This indicates that the PAM / COF composite material, as an adsorbent for treating methyl orange wastewater, has good renewability and durability. This demonstrates that the PAM / COF composite material is not only structurally stable but also reusable, thus reducing wastewater treatment costs and showing great potential for application in practical dye wastewater treatment.

[0058] The PAM / COF composite material prepared in this invention exhibits excellent mechanical strength and chemical stability, overcoming the shortcomings of poor mechanical properties in COF materials and enhancing the overall adsorption performance of the composite material. It demonstrates significant adsorption effects on methyl orange dye wastewater, maintaining excellent adsorption capacity across a wide pH range (from acidic to neutral) and varying temperatures (from room temperature to high temperatures), showing minimal influence from environmental conditions and improving its applicability in practical applications. It also exhibits good adsorption performance for other common dyes (such as methylene blue and Congo red). Therefore, the PAM / COF composite material prepared in this invention is suitable for treating various types of dye wastewater and has broad application prospects in the textile, printing, and dyeing industries. Furthermore, the PAM / COF composite material can be regenerated through simple alkaline washing, simplifying the regeneration process, reducing material consumption and costs, and improving economic efficiency. The high adsorption capacity of the PAM / COF composite material can accelerate wastewater treatment, improve treatment efficiency, and enhance the overall economic benefits of the wastewater treatment process.

[0059] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. The present invention can also have other embodiments based on the above structure and function, which will not be listed hereafter. Therefore, any simple modifications, equivalent changes, and alterations made by those skilled in the art to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a PAM / COF composite material for treating dye wastewater, characterized in that... Includes the following steps: (1) Weigh a certain amount of p-toluenesulfonic acid monohydrate and trialdehyde phloroglucinol, add them to deionized water, and sonicate for 10-20 min to obtain mixed solution A; (2) Take another certain volume of deionized water and add acrylamide, N,N-methylenebisacrylamide, polyvinylpyrrolidone, PEG-200 polyethylene glycol and Tween 20 to it in sequence. Disperse by ultrasonication until completely and evenly dispersed to obtain an aqueous phase. (3) Mix benzene, n-heptane and cyclohexane in a volume ratio of 1:1:2.5 and stir thoroughly to obtain the oil phase; (4) According to the volume ratio of water phase to oil phase of 2:1, take a certain amount of water phase prepared in step (2) and oil phase prepared in step (3), add the oil phase to the water phase while stirring. After the oil phase is completely added, continue stirring until a milky white oil-in-water emulsion is formed. Add ammonium persulfate to the oil-in-water emulsion, stir evenly, and then transfer the mixture to a reaction vessel with a polytetrafluoroethylene liner. Add N,N,N',N'-tetramethylethylenediamine to the reaction vessel with a polytetrafluoroethylene liner and stir quickly evenly. Then seal the reaction vessel with a polytetrafluoroethylene liner and place it in an oven at 55°C for 8~20 min. After the reaction is completed, wash the obtained product three times with methanol by centrifugation, and then dry the centrifuged product in a vacuum oven at 50°C for 8~12 h to obtain porous polyacrylamide powder, which is denoted as PAM powder. (5) Add PAM powder to the mixed solution A in step (1) and stir evenly to obtain mixed solution B; add diaminoanthraquinone to mixed solution B, mix and stir evenly, and then transfer to a reaction vessel with a polytetrafluoroethylene liner. Heat the reaction vessel with the polytetrafluoroethylene liner at 120°C for 18 h to allow it to react fully. After the reaction is completed, let the product cool naturally to room temperature and then perform vacuum drying to obtain a porous polyacrylamide / COF composite material, which is denoted as PAM / COF composite material.

2. The method for preparing the PAM / COF composite material for treating dye wastewater as described in claim 1, characterized in that... In step (1), the mass ratio of p-toluenesulfonic acid monohydrate to trialdehyde phloroglucinol is 22:5, and the volume ratio of deionized water to the total mass of p-toluenesulfonic acid monohydrate and trialdehyde phloroglucinol is 8 mL: 27 mg.

3. The method for preparing the PAM / COF composite material for treating dye wastewater as described in claim 1 or 2, characterized in that... In step (2), the mass ratio of acrylamide, N,N-methylenebisacrylamide, polyvinylpyrrolidone, PEG-200 polyethylene glycol, and Tween 20 is 13:1:1:1.2:8; the volume ratio of deionized water in step (2) to that in step (1) is 1:

1.

4. The method for preparing the PAM / COF composite material for treating dye wastewater as described in claim 1, characterized in that... The stirring speed in step (4) is 1500 rpm.

5. The method for preparing the PAM / COF composite material for treating dye wastewater as described in claim 1, characterized in that... In step (4), the concentration of ammonium persulfate in the oil-in-water emulsion is 1.25 mg / mL, and the volume ratio of N,N,N',N'-tetramethylethylenediamine to the volume of the oil-in-water emulsion is 1:

120.

6. The method for preparing the PAM / COF composite material for treating dye wastewater as described in claim 1 or 2, characterized in that... In step (5), the mass ratio of diaminoanthraquinone to trialdehyde phloroglucinol in step (1) is 3:

5.

7. The method for preparing the PAM / COF composite material for treating dye wastewater as described in claim 1, characterized in that... The PAM powder prepared in step (4) is a near-spherical particle with a particle size of 300~600 μm; in the PAM / COF composite material prepared in step (5), the COF material is attached to the pore structure of the PAM material, and the particle size of the COF material is 50~200 nm.

8. The application of the PAM / COF composite material obtained by the preparation method as described in claim 1 in the treatment of dye wastewater.

9. The application as described in claim 8, characterized in that... The concentration of the dye wastewater is 30~50 mg / L, and the mass ratio of the added PAM / COF composite material to the volume of the dye wastewater is 3 mg : 10 mL.

10. The application as described in claim 8, characterized in that... The pH of the dye wastewater is >7, and the adsorption equilibrium time of the PAM / COF composite material for the dye wastewater is 100~120 min.

Images