A d-a type imine group conjugated microporous polymer catalyst for activating persulfate and a preparation method and application thereof

Abstract

The present application relates to a kind of D-A type imine group conjugated microporous polymer catalyst activated with persulfate and its preparation method and application, the catalyst is prepared by Buchwald-Hartwig coupling reaction of benzothiadiazole monomer and aromatic amine monomer.The catalyst prepared in the present application has high efficient degradation performance to various organic pollutants, wide applicable pH range and confined enhanced mass transfer etc.Characteristics;The catalytic membrane with mass transfer enhancement can be further prepared by the present application.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nanomaterials and water treatment, and particularly relates to a D-A type imine group conjugated microporous polymer catalyst for activating persulfate and application of a preparation method thereof. BACKGROUND

[0002] With the development of the times, the industrial level of human gradually improves, and new pollutants contained in discharged wastewater include persistent organic pollutants (POPs), endocrine disruptors (EDCs), antibiotics and the like, which seriously affect water quality and endanger human health. The persulfate-based advanced oxidation process (AOPs) is considered as a potential water treatment technology for efficiently degrading these pollutants due to its multiple active oxygenated species (ROS), strong oxidation ability, and easy transportation of persulfate solid powder. The catalyst for activating persulfate is the core of the technology. Metal catalysts and non-metal carbon-based catalysts are the mainstream catalysts currently studied. However, the metal catalysts have the problem of secondary pollution of metal leakage, and the non-metal carbon-based catalysts have the problem of weak stability of active sites. Therefore, it is of important research significance to design and develop a new type of high-performance catalyst for activating persulfate for promoting the degradation of new pollutants.

[0003] Polymer-based catalysts have the problem of no metal pollution, and the molecular designability improves the possibility of preparing high-performance persulfate, and are a potential green high-performance activator. However, the polymer catalysts are often attacked by •OH and SO4 - and other non-selective free radicals, resulting in poor stability. In addition, under the flow bed process, the mass transfer of pollutants is limited, the utilization rate of generated free radicals is low, and the polymer is further attacked, resulting in a significant decrease in stability. SUMMARY

[0004] The purpose of the present application is to provide a D-A type imine group conjugated microporous polymer catalyst for activating persulfate and a preparation method and application thereof, so as to solve the technical problems of poor stability of the polymer catalyst and low utilization rate of active free radicals.

[0005] The present application provides a D-A type imine group conjugated microporous polymer catalyst for activating persulfate, which is prepared by generating a conjugated microporous polymer catalyst through Buchwald-Hartwig coupling reaction of a benzothiadiazole monomer and an aromatic amine monomer.

[0006] Preferably, the benzothiadiazole monomer includes at least one of 4,7-dibromo-2,1,3-benzothiadiazole or 4,7-dibromo-benzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole); and the aromatic amine monomer includes tri(4-aminophenyl)amine and the like.

[0007] Preferably, the catalyst has one of the following structures:

[0008] ,

[0009] .

[0010] This invention provides a method for preparing the above-mentioned DA-type imine-based conjugated microporous polymer catalyst for persulfate activation, comprising the following steps: placing a reaction system of benzothiadiazole monomers, aromatic amine monomers, and Buchwald-Hartwig coupling reaction in a molar ratio of 2:1 to 3 in a Schlenk tube and reacting it at 60-150°C for 12-72 h under a nitrogen atmosphere; subsequently filtering and vacuum drying at 25-80°C for 2-72 h to obtain a powdered catalyst.

[0011] Preferably, the reaction system of the Buchwald-Hartwig coupling reaction comprises: a solvent including at least one of toluene, chloroform, tetrahydrofuran, or N,N-dimethylformamide; a palladium catalyst including at least one of palladium acetate, tris(dibenzylacetone)palladium, or bis(dibenzylacetone)palladium; a ligand including at least one of 1,1'-binaphthyl-2,2'-bisdiphenylphosphine, 2-cyclohexylphosphine-2',4',6'-triisopropylbiphenyl, or 1,1-bis(diphenylphosphine)ferrocene; and a base including at least one of sodium tert-butoxide cesium carbonate, sodium tert-butoxide, or potassium tert-butoxide.

[0012] More preferably, during the filtration process, the filtrate is washed sequentially with anhydrous methanol, chloroform, and deionized water until it is colorless and transparent.

[0013] This invention provides an application of the above-mentioned persulfate-activated DA-type imine-conjugated microporous polymer catalyst in the removal of organic pollutants, comprising: adding the above-mentioned catalyst to an organic pollutant solution and placing it in a constant-temperature shaker for shaking at a temperature of 5-50°C for 5-60 min and a rotation speed of 100-400 r / min. -1 The dosage of the catalyst is 0.01~0.5 g / L. -1 .

[0014] Preferably, the organic pollutant solution comprises persulfate and organic pollutants, and has a pH value of 2–11; the persulfate concentration is 0.1–10 mmol / L. -1 The organic pollutant includes at least one of permonosulfate (PMS) or perdisulfate (PDS); the concentration of the organic pollutant is 1-50 mg / L. -1 This includes at least one of phenol, tetracycline, acid red or methylene blue, and bisphenol A (BPA).

[0015] The application also provides a preparation method of a D-A type imine-based conjugated microporous polymer catalytic membrane activated by persulfate, comprising:

[0016] (1) placing the above catalyst in N-methylpyrrolidone, adding carbon nanotubes (CNT), and ultrasonically treating to prepare a dispersion liquid;

[0017] (2) preparing a catalytic membrane by vacuum filtration, and then drying the catalytic membrane in a vacuum drying oven after washing.

[0018] Preferably, the catalyst is added in an amount of 2-50 mg in step (1), the volume of N-methylpyrrolidone is 40-200 mL; the mass ratio of the catalyst to the carbon nanotubes is 1:0.2-4; the ultrasonic temperature is 20-30°C, and the time is 0.5-24 h.

[0019] Preferably, the substrate used for preparing the catalytic membrane in step (2) is an organic Nylon 66 microporous filter membrane with a diameter of 30-60 mm and a pore size of 0.1-0.3 μm; after washing, the catalytic membrane is immersed in deionized water for 3-12 h, and then dried at a temperature of 20-100°C for 3-24 h.

[0020] More preferably, the washing comprises sequentially washing with anhydrous ethanol, 50% ethanol solvent, and deionized water until the filtrate does not contain N-methylpyrrolidone.

[0021] The application also provides an application of the above catalytic membrane in continuous flow removal of organic pollutants, comprising: flowing the organic pollutant solution through the catalytic membrane at a flow rate of 0.5-5 mL min -1 .

[0022] The application is based on a D-A type imine-based conjugated microporous polymer catalyst with characteristics of a polyaniline-like electron donor (D) prepared by Buchwald-Hartwig coupling reaction of a benzothiadiazole electron acceptor (A) and an aromatic amine monomer. The polymer catalyst has the following characteristics: (1) the unique redox characteristics of the imine-based conjugated microporous polymer can oxidize persulfate to O2• - and 1 O2, avoiding oxidation of itself; (2) the D-A effect endows the imine-based conjugated microporous polymer with a narrow band gap, which is beneficial to rapid transmission of electrons, so that the polymer catalyst has a kinetic constant comparable to a metal catalyst; (3) the conjugation characteristics of the polymer make it easy to perform Π-Π conjugation self-assembly with carbon nanotubes, so that a catalytic membrane can be further prepared, mass transfer of pollutants is strengthened, the polymer is effectively prevented from being attacked by free radicals, and the stability is high.

[0023] Advantages

[0024] (1) The powder catalyst prepared by the present application has the characteristics of rapid degradation of pollutants (the removal rate of bisphenol A is nearly 100% within 30 min, the kinetic k value is as high as 0.21 min -1 ), wide applicable pH range, and limited enhancement of mass transfer, and has high-efficiency degradation performance on various organic pollutants.

[0025] (2) The catalytic film with mass transfer enhancement prepared by the present application can keep the removal rate of bisphenol A at more than 99.99% in a continuous degradation process of up to 100 h.

[0026] (3) The present application provides a new idea for the design and preparation of high-performance non-metal-based polymer catalysts, and has potential application value in the field of emerging organic pollutant degradation. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is the SEM graph of TPBT catalyst in Example 1 of the present application.

[0028] Figure 2 It is the degradation rate of bisphenol A-containing wastewater with TPBT catalyst in Example 3 of the present application and carbon nanotube (CNT) catalyst in Comparative Example 1 changing with time.

[0029] Figure 3 It is the treatment flux and degradation rate of bisphenol A-containing wastewater with TPBT@CNT catalytic film in Example 5 of the present application changing with time.

[0030] Figure 4 It is the electron paramagnetic resonance spectrum of TPBT catalyst in Example 6 of the present application. DETAILED DESCRIPTION

[0031] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not used to limit the scope of the present application. In addition, it should be understood that those skilled in the art can make various modifications or changes to the present application after reading the content taught by the present application, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

[0032] Example 1

[0033] The present embodiment provides a D-A type imine group conjugated microporous polymer catalyst for activation of persulfate, and a preparation method thereof, which comprises the following steps:

[0034] Tris(4-aminophenyl)amine (95.81 mg, 0.33 mmol, TCI), 4,7-dibromo-2,1,3-benzothiadiazole (147 mg, 0.5 mmol, Sinopharm) were placed in a Schlenk tube (100 mL), and bis(dibenzylideneacetone)palladium (17.25 mg, 0.03 mmol, TCI), 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (21.42 mg, 0.45 mmol, TCI), sodium tert-butoxide (336.4 mg, 3.5 mmol, Vankel), sodium fluoride (21 mg, 0.5 mmol, TCI) were added under nitrogen atmosphere, 50 mL of toluene, and the coupling reaction was carried out in an oil bath at 110°C for 48 h. After the reaction was completed, the unreacted raw materials and oligomers were removed by washing with anhydrous methanol, chloroform, and deionized water at 60°C for two hours each time. Finally, it was dried in a vacuum oven at 40°C for 24 h to obtain the polymer catalyst (TPBT, corresponding to the P2 structure in the above structural formula), and the SEM image thereof is shown in Figure 1

[0035] Example 2

[0036] The present embodiment provides a D-A type imine-based conjugated microporous polymer catalyst for activating persulfate, and a preparation method thereof, which comprises the following steps:

[0037] Tris(4-aminophenyl)amine (95.81 mg, 0.33 mmol, TCI), 4,7-dibromo-2,1,3-benzothiadiazole (147 mg, 0.5 mmol, Sinopharm) were placed in a Schlenk tube (100 mL), and bis(dibenzylideneacetone)palladium (17.25 mg, 0.03 mmol, TCI), 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (21.42 mg, 0.45 mmol, TCI), sodium tert-butoxide (336.4 mg, 3.5 mmol, Vankel), sodium fluoride (21 mg, 0.5 mmol, TCI) were added under nitrogen atmosphere, 50 mL of toluene, and the coupling reaction was carried out in an oil bath at 110°C for 48 h. After the reaction was completed, the unreacted raw materials and oligomers were removed by washing with anhydrous methanol, chloroform, and deionized water at 60°C for two hours each time. Finally, it was dried in a vacuum oven at 40°C for 24 h to obtain the polymer catalyst (TPBT, corresponding to the P2 structure in the above structural formula), and the SEM image thereof is shown in

[0038] Example 3

[0039] The present embodiment provides an application of a D-A type imine-based conjugated microporous polymer catalyst for activating persulfate in removing organic pollutants, and the specific process comprises: ​

[0040] The polymer catalyst TPBT prepared in Example 1 was added to the organic contaminant solution to obtain a solution containing 25 mg / L of the organic contaminant. - 1 Organic contaminant, 2 mmol / L -1 Peroxydisulfate (PMS), 0.10 g / L -1 The mixed solution of TPBT and PMS with pH 6 was placed in a constant temperature vibration bed at 25°C and shaken at a speed of 300 r / min. Samples were taken at different time points, and the concentration of the organic contaminant in the solution was determined by high performance liquid chromatography (mobile phase: 70% methanol and 30% ultrapure water).

[0041] Bisphenol A was used as a model contaminant, and samples were taken at 2 min, 4 min, 6 min, 12 min, 18 min, 24 min, and 30 min to investigate the degradation effect of the catalyst on the organic contaminant within 30 min. The experimental results are shown in Table 1. Figure 2 As shown in Table 1, the degradation rate of bisphenol A by the catalyst in the TPBT / PMS catalytic system remained above 99.99% within 30 min, and the calculated k was 0.21 min -1 , indicating that the polymer catalyst has a good degradation effect on organic contaminants, and the TPBT / PMS system has good practicability.

[0042] Comparative Example 1

[0043] This comparative example provides an application of a carbon nanotube catalyst in removing organic contaminants. The specific process is as described in Example 3, except that there is no polymer TPBT and PMS. The degradation rate of bisphenol A is shown in Table 1. Figure 2 As shown in Table 1, the degradation effect of the single carbon nanotube catalyst on organic contaminants is significantly worse than that of TPBT / PMS.

[0044] Example 4

[0045] This example provides a preparation method of a D-A imine group conjugated microporous polymer catalyst film activated by persulfate, as follows:

[0046] (1) 15 mg of the polymer catalyst TPBT prepared in Example 1 was added to 200 mL of an N-methylpyrrolidone solution, and 20 mg of carbon nanotubes (CNT) was added at the same time. The mixture was ultrasonically dispersed at 30°C for 24 h to prepare a dispersion liquid.

[0047] (2) The catalytic membrane is prepared by vacuum filtration method. The membrane substrate is an organic Nylon 66 microporous filter membrane with a diameter of 45 mm and a pore size of 0.2 μm. The membrane is sequentially washed with anhydrous ethanol, 50% ethanol solution and deionized water until the filtrate does not contain N-methyl pyrrolidone solution. The catalytic membrane is immersed in deionized water for 3-12 h. The immersed membrane is dried at a temperature of 60°C for 24 h. After washing, the catalytic membrane is dried in a vacuum drying oven to obtain the TPBT@CNT catalytic membrane.

[0048] Example 5

[0049] The present embodiment provides an application of a persulfate-activated D-A imine-based conjugated microporous polymer catalytic membrane in continuous flow removal of organic pollutants, which specifically comprises:

[0050] The TPBT@CNT catalytic membrane prepared in Example 4 is placed in a plug flow reactor, and a flow-through dead-end filtration method is used. The organic pollutant solution (containing 5 mg / L - 1 organic pollutants, 1 mmol / L -1 persulfate (PMS), pH 6) is passed through the catalytic membrane at a pressure of 1 bar. Samples are taken at different time points at the water outlet, and the concentration of organic pollutants in the solution is determined by high performance liquid chromatography (mobile phase: 70% methanol and 30% ultrapure water).

[0051] Bisphenol A is used as a model pollutant, and samples are taken at the water outlet after 5 min, 10 min, 15 min, 30 min, 45 min, 60 min, 90 min, 120 min, 3 h, 4 h, 5 h, 6 h, 8 h, 10 h, and every 5 h thereafter within 100 h. The degradation effect of the catalytic membrane on organic pollutants within 100 h is investigated. The experimental results are shown in Table 1. Figure 3 As shown in Table 1, the degradation rate of the catalytic membrane on bisphenol A in the catalytic filtration system is maintained at more than 99.99% within 100 h, indicating that the catalytic membrane has good degradation effect on organic pollutants, and the TPBT@CNT catalytic membrane / PMS system has good practicability.

[0052] Example 6

[0053] The present embodiment provides a method for detecting active oxygen species in the activation of PMS, which is as follows:

[0054] The polymer catalyst TPBT in Example 1 is added to an organic pollutant solution to obtain an organic pollutant solution containing 25 mg / L - 1 organic pollutants, 2 mmol / L -1 persulfate (PMS), 0.10 g / L -1TPBT, pH 6 mixed solution, which is placed in 25 ℃ constant temperature vibration bed. At 30 min, sample, take 40 μL sample solution into a plastic tube containing 20 μL active oxygen species capture agent (free radical capture agent: dimethylpyridine N-oxide (DMPO), singlet oxygen capture agent: 2,2,6,6-tetramethylpiperidine (TEMP)), shake uniformly, and then use an electron paramagnetic resonance spectrometer (EPR) to test active oxygen species signal intensity, and the results are shown in Figure 4 Fig. 1, wherein (a) is TMEP capturing singlet oxygen, and (b) is DMPO capturing free radicals. As can be seen from the figure, when DMPO and TEMP are used as capture agents, characteristic peaks of superoxide radicals (O2 •- ) and singlet oxygen (O2 1 ) appear, indicating that superoxide radicals and singlet oxygen are the main active radicals in the TPBT / PMS system.

Claims

1. A DA-type imine-based conjugated microporous polymer catalyst for persulfate activation, characterized in that, The catalyst is prepared by a Buchwald-Hartwig coupling reaction of a benzothiadiazole monomer and an aromatic amine monomer; the benzothiadiazole monomer is at least one of 4,7-dibromo-2,1,3-benzothiadiazole or 4,7-dibromobenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole); the aromatic amine monomer is tris(4-aminophenyl)amine.

2. The catalyst according to claim 1, characterized in that, The catalyst has one of the following structures: 、 。 3. A method for preparing a DA-type imine-based conjugated microporous polymer catalyst for persulfate activation as described in claim 1, comprising the following steps: placing a reaction system of benzothiadiazole monomers, aromatic amine monomers, and Buchwald-Hartwig coupling reaction in a molar ratio of 2:1 to 3 in a Schlenk tube and reacting it at 60-150°C for 12-72 h under a nitrogen atmosphere; subsequently filtering and vacuum drying at 25-80°C for 2-72 h to obtain a powdered catalyst.

4. The preparation method according to claim 3, characterized in that, The reaction system for the Buchwald-Hartwig coupling reaction is as follows: the solvent used includes at least one of toluene, chloroform, tetrahydrofuran, or N,N-dimethylformamide; the palladium catalyst used includes at least one of palladium acetate, tris(dibenzylacetone)palladium, or bis(dibenzylacetone)palladium; the ligand used includes at least one of 1,1'-binaphthyl-2,2'-bisdiphenylphosphine, 2-cyclohexylphosphine-2',4',6'-triisopropylbiphenyl, or 1,1-bis(diphenylphosphine)ferrocene; and the base used includes at least one of sodium tert-butoxide cesium carbonate, sodium tert-butoxide, or potassium tert-butoxide.

5. The application of the DA-type imine-based conjugated microporous polymer catalyst for persulfate activation as described in claim 1 in the removal of organic pollutants, characterized in that, The catalyst was added to the organic pollutant solution and placed in a constant-temperature shaker. The temperature was set at 5-50°C, the time at 5-60 min, and the rotation speed at 100-400 r / min. -1 The dosage of the catalyst is 0.01~0.5 g / L. -1 .

6. The application according to claim 5, characterized in that, The organic pollutant solution includes persulfate and organic pollutants, with a pH value of 2–11; the persulfate concentration is 0.1–10 mmol / L. -1 The organic pollutant includes at least one of persulfate or perdisulfate; the concentration of the organic pollutant is 1-50 mg / L. -1 It includes at least one of phenol, tetracycline, acid red or methylene blue and bisphenol A.

7. A method for preparing a DA-type imine-based conjugated microporous polymer catalytic membrane for persulfate activation, comprising the following steps: (1) The catalyst as described in claim 1 is placed in N-methylpyrrolidone, carbon nanotubes are added, and the mixture is sonicated to form a dispersion; (2) The catalytic membrane was prepared by vacuum filtration, washed and then dried in a vacuum drying oven.

8. The preparation method according to claim 7, characterized in that, In step (1), the amount of catalyst added is 2~50mg, the volume of N-methylpyrrolidone is 40~200mL, the mass ratio of catalyst to carbon nanotubes is 1:0.2~4, the ultrasonic temperature is 20~30℃, and the time is 0.5~24h.

9. The preparation method according to claim 7, characterized in that, In step (2), the substrate used to prepare the catalytic membrane is an organic Nylon66 microporous filter membrane with a diameter of 30-60 mm and a pore size of 0.1-0.3 μm. After washing, the catalytic membrane is soaked in deionized water for 3-12 h and then dried at a temperature of 20-100℃ for 3-24 h.

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