Single / double metal atom modified covalent organic framework catalytic material as well as preparation method and application thereof

Abstract

The invention provides a single / double metal atom modified covalent organic framework catalytic material and a preparation method and application thereof, and belongs to the technical field of Fenton-like method wastewater treatment, 1, 3, 5-triformyl phloroglucinol and 2, 2 '-bipyridine-5, 5'-diamine are used for preparing TB-COF, the TB-COF is used for preparing TB-COF, the TB-COF is used for preparing TB-COF, and the TB-COF is used for preparing TB-COF. One or two metals of iron, manganese, cobalt or nickel are modified to obtain the single / double metal atom modified covalent organic framework catalytic material, and the application of the material in treatment of micropollutants in a water body is also provided. The single / double metal atom modified covalent organic framework catalytic material provided by the invention has relatively high reaction activity, is an excellent Fenton-like catalytic active material, can generate various active oxygen species and chlorine dioxide after being in contact with chlorite, has the removal efficiency of more than 75% on various water body micro-pollutants, and can be used as a catalyst for treating water body micro-pollutants. And after multiple cycles, high catalytic activity and good structural integrity can still be maintained.

Description

Technical Field

[0001] The present invention relates to the technical field of Fenton-like wastewater treatment, and more specifically, to a single / double metal atom modified covalent organic framework catalytic material and a preparation method and application thereof. Background Art

[0002] With the growth of population and economic development, water pollution is becoming more and more serious worldwide. Some trace but highly toxic, persistent and bioaccumulative pollutants in water, such as pharmaceuticals and personal care products (PPCPs), hormones, disinfection byproducts (DBPs), perfluorinated compounds (PFASs), antibiotic resistance genes (ARGs), etc., are called water micropollutants, and are becoming a pollution problem that needs to be solved urgently. Among them, antibiotic pollutants have received widespread attention due to their persistence and ecological risks in the environment. Even trace levels of antibiotics will remain and accumulate in the soil and water environment. Residual antibiotics can induce the accumulation of bacterial resistance and the generation of antibiotic resistance genes in microorganisms, and damage the ecosystem. Long-term contact or drinking of water sources containing antibiotics by animals, including humans, may cause disorders in the metabolic process in the organism, resulting in abnormalities or damage to the organism. Therefore, there is an urgent need for a safe and efficient method to remove micropollutants represented by antibiotics in water.

[0003] The traditional water pollutant treatment technology is the advanced oxidation treatment method represented by the Fenton method. 2+ / H2O2 is a degradation system, and divalent iron ions are used as catalysts to activate H2O2 to produce hydroxyl radicals (·OH), thereby oxidizing pollutants in water into small molecules or mineralizing them into CO2. However, the traditional Fenton system is greatly affected by the background water quality and is difficult to transport and store raw materials. In recent years, Fenton-like technologies have been increasingly developed. Based on this, a series of advanced catalytic oxidation water treatment technologies have been derived. Fenton-like technologies that use chlorite to activate chlorite to produce chlorine dioxide and active free radicals have received widespread attention. As a common oxidant and disinfectant, chlorine dioxide is widely used in the degradation of micropollutants in water bodies, sterilization and disinfection, etc. It has the characteristics of selective oxidation and shows high selective oxidation characteristics for pollutants with electron-donating functional groups. At the same time, chlorine dioxide undergoes oxidation reactions by electron transfer, almost no chlorination reaction occurs, almost no disinfection by-products are produced, and it has low dependence on pH.

[0004] At present, there have been studies on the degradation of micropollutants by using metal oxides containing surface oxygen vacancies, bismuth oxyhalides (BiOX) as chlorite activation materials, or by using sunlight and ultraviolet light as light sources to activate chlorite, but there are still disadvantages such as insufficient catalytic activity, metal ion leaching, and the need for external energy drive. Compared with previous materials, covalent organic frameworks have the advantages of clearer internal unit structure, lower density, and easier interface modification and regulation. Bipyridine functional groups have attracted attention due to their rich functionality. Their electron-rich groups can not only act as Brønsted basic sites and proton coordination to form pyridinium, but also act as Lewis base sites to combine with Lewis acids such as electron-poor metal ions to construct rich and stable surface active metal sites, which has attracted people's research interest.

[0005] The prior art discloses a metal-modified covalent organic framework material, in which a metal-modified covalent organic framework M-TfpBpy-COF with piezoelectricity is constructed by modifying different metals on TfpBpy-COF. The metal-modified COF exhibits excellent piezoelectric catalytic performance and can be used in the piezoelectric catalytic preparation of hydrogen peroxide. The COF material contains bipyridine functional groups and certain surface active metal sites, but cannot be used as an activation material for chlorite, that is, it cannot be used in a Fenton-like system.

[0006] Therefore, the development of a single / double metal atom-modified covalent organic framework catalytic material with good chlorite activation ability to degrade water micropollutants and its preparation method and application have important research significance and application value. Summary of the invention

[0007] The present invention aims to overcome the technical problems of poor catalytic activity and insufficient activation ability of covalent organic framework catalytic materials in the prior art in Fenton-like systems, and to provide a single / double metal atom-modified covalent organic framework catalytic material with good chlorite activation ability to degrade micropollutants in water bodies, as well as a preparation method and application thereof.

[0008] Therefore, the primary object of the present invention is to provide a method for preparing a single / double metal atom modified covalent organic framework catalytic material.

[0009] Another object of the present invention is to provide a single / double metal atom modified covalent organic framework catalytic material prepared by the above preparation method.

[0010] Another object of the present invention is to provide an application of the above-mentioned single / double metal atom modified covalent organic framework catalytic material in treating antibiotics in water.

[0011] Another object of the present invention is to provide a method for degrading antibiotics in water.

[0012] To achieve the above object, the present invention adopts the following technical solutions:

[0013] The present invention provides a method for preparing a single / double metal atom modified covalent organic framework catalytic material, comprising the following steps:

[0014] One or two metals selected from iron, manganese, cobalt or nickel are used to modify TB-COF by a solvothermal method to obtain M-TB-COF;

[0015] The covalent organic framework TB-COF is synthesized using 1,3,5-triformylphloroglucinol and 2,2'-bipyridine-5,5'-diamine as precursors.

[0016] The present invention provides a method for preparing a diatomic metal-modified covalent organic framework catalytic material, wherein different metals are loaded on a bipyridyl covalent organic framework TB-COF in a single or diatomic form through a specific process, thereby constructing a series of M-TB-COFs with good chlorite activation ability. The metal-loaded COF exhibits excellent antibiotic degradation performance, can effectively cope with the influence of background ions in water quality, and provides a safe and efficient method for removing antibiotics from water.

[0017] Among them, TB-COF has a bipyridine functional group, which can not only serve as a Brønsted basic site and proton coordination to form pyridinium, but also as a Lewis base site to combine with Lewis acids such as electron-poor metal ions to construct surface active metal sites. Therefore, the present invention uses TB-COF as a substrate for material modification.

[0018] The M-TB-COF of the present invention may be at least one of Fe-TB-COF, Co-TB-COF, Mn-TB-COF, Ni-TB-COF, FeCo-TB-COF, FeMn-TB-COF, FeNi-TB-COF, CoMn-TB-COF, CoNi-TB-COF or MnNi-TB-COF.

[0019] Preferably, the metal is derived from a metal compound, and the mass ratio of the metal to TB-COF is 0.5 to 2.5:1.

[0020] More preferably, the mass ratio of the metal compound to TB-COF is 1 to 2:1.

[0021] The inventors found that the catalytic performance of M-TB-COF after synthesis with different metal loadings is different, which affects the degradation efficiency of antibiotics. By increasing the mass ratio of metals, the degradation efficiency obtained shows a volcano curve that first increases and then decreases. A lower metal loading will result in fewer reactive sites on the covalent organic framework and a poor catalytic effect. Excessive metal loading does not significantly improve catalytic performance. Excessive metals may form atomic islands or metal clusters on the surface of the covalent organic framework, resulting in changes or shielding of active sites, inhibiting the activation of chlorite.

[0022] Preferably, the solvothermal method is carried out for 6 to 8 hours.

[0023] Preferably, the temperature of the solvothermal method is 65-80°C.

[0024] Preferably, the reaction solvent of the solvothermal method is anhydrous ethanol.

[0025] Preferably, the molar ratio of the 1,3,5-triformylphloroglucinol to the 2,2'-bipyridine-5,5'-diamine is 1:0.7-3.

[0026] More preferably, the molar ratio of the 1,3,5-triformylphloroglucinol to the 2,2'-bipyridine-5,5'-diamine is 1:1.5.

[0027] Preferably, the method for preparing the single / double metal atom modified covalent organic framework catalytic material further comprises the following steps:

[0028] After the reaction, centrifugal washing and vacuum drying were performed to obtain M-TB-COF.

[0029] Preferably, the solvent for the centrifugal washing is anhydrous ethanol, methanol, or pure water, and the washing times are 3 to 5 times.

[0030] Preferably, the vacuum drying temperature is 70° C. to 90° C., and the vacuum drying time is 12 h to 24 h. More preferably, the temperature is 80° C., and the vacuum drying time is 14 h.

[0031] The above-mentioned certain raw material ratio, activation temperature and time condition range are preferably selected to improve the utilization rate of raw materials for synthesizing the covalent organic framework, and the catalytic performance of the obtained covalent organic framework catalyst is better.

[0032] Preferably, the method for preparing the covalent organic framework TB-COF comprises the following steps: dissolving 1,3,5-triformylphloroglucinol and 2,2'-bipyridine-5,5'-diamine in an organic solvent, and reacting them under acidic conditions to synthesize TB-COF.

[0033] Preferably, the organic solvent is a mixture of dimethylacetamide and o-dichlorobenzene.

[0034] Preferably, the acidic condition is adjusted with 4-8 M acetic acid.

[0035] Preferably, the amount of acetic acid added is 0.4-0.8 mL.

[0036] More preferably, the preparation method of the covalent organic framework TB-COF is:

[0037] 1,3,5-triformylphloroglucinol and 2,2'-bipyridine-5,5'-diamine are uniformly dispersed in a mixed solution of dimethylacetamide and o-dichlorobenzene, acetic acid is added, and the mixture is degassed by freeze-vacuum-thaw cycles and then dried; the mixture is washed and filtered with one or more of dimethylacetamide, dichloromethane, acetone or methanol; and the obtained solid is vacuum activated.

[0038] Preferably, the uniform dispersion method is ultrasonic treatment for 8 to 12 minutes.

[0039] Preferably, the vacuum activation temperature is 70-150°C, more preferably 120°C.

[0040] Preferably, the vacuum activation time is 8 to 16 hours, more preferably 12 hours.

[0041] The reason for preferring the above steps to prepare the covalent organic framework TB-COF is that the TB-COF material structure prepared by this step is more complete and stable, and the reaction conditions are easier to control in application.

[0042] The invention protects a single / double metal atom modified covalent organic framework catalytic material, which is prepared by the above preparation method.

[0043] The application of the above-mentioned single / double metal atom modified covalent organic framework catalytic material in treating micro-pollutants in water bodies is also within the protection scope of the present invention.

[0044] The present invention also protects a method for degrading antibiotics in water, comprising the following steps:

[0045] The single / double metal atom modified covalent organic framework catalytic material is added into water containing antibiotics, chlorite is added, and the reaction is stirred at 450-700 rpm.

[0046] A stirring rate that is too slow will reduce the chance of contact and activation between the material and chlorite, while a stirring rate that is too fast will increase energy consumption and reduce the stability of the system.

[0047] Preferably, the stirring is performed at room temperature, and the stirring time is 10 min to 120 min, more preferably 15 min to 30 min.

[0048] Preferably, the dosage of the single / double metal atom modified covalent organic framework catalytic material is 3 mg to 15 mg, more preferably 3 mg, 5 mg, 10 mg, 15 mg, and even more preferably 5 mg.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] 1. The present invention provides a method for preparing a covalent organic framework catalytic material modified with a single or double metal atom. TB-COF is prepared by using 1,3,5-triformylphloroglucinol and 2,2'-bipyridine-5,5'-diamine as precursors, and then single or double metal atoms are loaded to obtain M-TB-COF. The M-TB-COF has high reaction activity and is an excellent Fenton-like catalytic active material. After contacting with chlorite, the M-TB-COF can produce a variety of active oxygen species and chlorine dioxide, and the removal efficiency of various water micropollutants can reach more than 75%.

[0051] 2. The single / double metal atom modified covalent organic framework catalytic material prepared by the present invention has good thermal stability and strong chemical stability, and can still maintain high catalytic activity and good structural integrity after multiple cycles. The material has the advantages of simple synthesis, non-toxicity, environmental protection and high efficiency, is easy to recycle and separate, can be reused, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a scanning electron microscope (SEM) image of the TB-COF material prepared in Comparative Example 2;

[0053] Figure 2 This is a scanning electron microscope (SEM) image of the FeCo-TB-COF material prepared in Example 1;

[0054] Figure 3 The X-ray diffraction (XRD) pattern of the FeCo-TB-COF material prepared in Example 1;

[0055] Figure 4 The electron spin resonance (ESR) spectrum of the hydroxyl radical of the FeCo-TB-COF material activated with chlorite prepared in Example 1;

[0056] Figure 5 The superoxide radical electron spin resonance (ESR) spectrum of the FeCo-TB-COF material prepared in Example 1 activated chlorite;

[0057] Figure 6 This is a UV-visible absorption spectrum of the FeCo-TB-COF catalyst prepared in Example 1 during the chlorite activation process;

[0058] Figure 7Performance test diagram of the M-TB-COF catalyst prepared in Examples 1, 5, 11, 12, and 13 for degrading the micropollutant sulfamethoxazole (SMX);

[0059] Figure 8 This is a test diagram of the cyclic stability performance of the FeCo-TB-COF catalyst prepared in Example 1;

[0060] Fig. 9 Performance test diagram of the M-TB-COF catalyst prepared in Examples 1, 14, 15, and 16 for degrading different micropollutants. DETAILED DESCRIPTION

[0061] In order to more clearly and completely describe the technical solution of the present invention, the present invention is further described in detail through specific embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention. Various changes can be made within the scope of the rights of the present invention.

[0062] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0063] The preparation methods of TB-COF in Examples 1 to 16 of the present invention and the comparative examples are as follows:

[0064] Add 63 mg of 1,3,5-triformylphloroglucinol (Tp) and 83.7 mg of 2,2'-bipyridine-5,5'-diamine (Bpy) to a high temperature resistant reaction bottle, add 4.5 mL of chromatographic grade DMAC and 1.5 mL of o-dichlorobenzene mixed solution to dissolve, and stir to disperse the solution evenly. Quickly add 0.6 mL of 6M acetic acid solution, adjust the pH, stir evenly for 10 minutes by ultrasonic, and quickly freeze the suspension into a solid with liquid nitrogen, and use a vacuum pump to evacuate the reactor to a vacuum state. After thawing, the aforementioned freezing and vacuuming process is cycled again. After a total of 5 freeze-vacuum-thaw cycles of degassing, the sealed vacuum reaction bottle is placed in a vacuum drying oven and reacted for 72 hours at 120°C. After the reaction is completed, the material is cooled to room temperature and centrifuged and washed with DMAC, acetone, dichloromethane and methanol until the supernatant is clear and colorless. The washed solid is placed in a vacuum drying oven at 150°C for 12 hours. After the reaction is completed, the material is cooled to room temperature and ground to obtain TB-COF.

[0065] Example 1 A bimetallic atom-modified covalent organic framework catalytic material (FeCo-TB-COF) and its preparation method and application

[0066] The method for preparing the bipyridine-based covalent organic framework catalytic material modified with iron and cobalt diatomic metals comprises the following steps:

[0067] 50 mg TB-COF, 25 mg ferric chloride (FeCl3), and 25 mg cobalt chloride (CoCl2) were added to a 100 mL round-bottom flask, and 30 mL of methanol was added to the flask as a solution. A corrosion-resistant stirring bar was added, and a condenser was added to the top of the round-bottom flask. The flask was placed in a water bath and stirred at 65°C for 6 hours. The obtained solid was washed with ethanol and pure water by centrifugation for 4 times, and dried at 80°C in a vacuum drying oven for 12 hours to obtain FeCo-TB-COF, a bipyridine-based covalent organic framework catalytic material modified with iron and cobalt diatomic metals.

[0068] 5 mg of the FeCo-TB-COF prepared above was added to the sulfamethoxazole solution and uniformly dispersed, and 0.5 mg of sodium chlorite was added to degrade the sulfamethoxazole in the water.

[0069] Example 2 A single metal atom modified covalent organic framework catalytic material (Co-TB-COF) and its preparation method and application

[0070] The method for preparing the bipyridine-based covalent organic framework catalytic material modified by cobalt single atom metal comprises the following steps:

[0071] 50 mg TB-COF and 50 mg cobalt chloride (CoCl2) were added to a 100 mL round-bottom flask, and 30 mL methanol was added to the flask as a solution. A corrosion-resistant stirring bar was added, and a condenser was added to the top of the round-bottom flask. The flask was placed in a water bath and stirred for 6 hours at 70°C. The obtained solid was washed by centrifugation with ethanol and pure water for 4 times, and dried in a vacuum drying oven at 80°C for 12 hours to obtain a cobalt single-atom metal-modified bipyridine-based covalent organic framework catalytic material Co-TB-COF.

[0072] 5 mg of the Co-TB-COF prepared above was added to the sulfamethoxazole solution and uniformly dispersed, and 0.5 mg of sodium chlorite was added to degrade the sulfamethoxazole in the water.

[0073] Example 3 A single metal atom modified covalent organic framework catalytic material (Mn-TB-COF) and its preparation method and application

[0074] The method for preparing the bipyridine-based covalent organic framework catalytic material modified by manganese single atom metal comprises the following steps:

[0075] 50 mg TB-COF and 50 mg manganese chloride (MnCl2) were added to a 100 mL round-bottom flask, and 30 mL of methanol was added to the flask as a solution. A corrosion-resistant stirring bar was added, and a condenser was added to the top of the round-bottom flask. The flask was placed in a water bath and stirred at 65°C for 6 hours. The obtained solid was washed with ethanol and pure water by centrifugation for 4 times, and dried at 80°C in a vacuum drying oven for 12 hours to obtain a cobalt single-atom metal-modified bipyridine-based covalent organic framework catalytic material Mn-TB-COF.

[0076] 5 mg of the Mn-TB-COF prepared above was added to the sulfamethoxazole solution and uniformly dispersed, and 0.5 mg of sodium chlorite was added to degrade the sulfamethoxazole in the water.

[0077] Example 4 A single metal atom modified covalent organic framework catalytic material (Ni-TB-COF) and its preparation method and application

[0078] The method for preparing the bipyridine-based covalent organic framework catalytic material modified by nickel single atom metal comprises the following steps:

[0079] 50 mg TB-COF and 50 mg manganese chloride (MnCl2) were added to a 100 mL round-bottom flask, and 30 mL methanol was added to the flask as a solution. A corrosion-resistant stirring bar was added, and a condenser was added to the top of the round-bottom flask. The flask was placed in a water bath and stirred for 6 hours at 70°C. The obtained solid was washed by centrifugation with ethanol and pure water for 4 times, and dried in a vacuum drying oven at 80°C for 12 hours to obtain a cobalt single-atom metal-modified bipyridine-based covalent organic framework catalytic material Ni-TB-COF.

[0080] 5 mg of the Ni-TB-COF prepared above was added to the sulfamethoxazole solution and uniformly dispersed, and 0.5 mg of sodium chlorite was added to degrade the sulfamethoxazole in the water.

[0081] Example 5 A single metal atom modified covalent organic framework catalytic material (Fe-TB-COF) and its preparation method and application

[0082] The method for preparing the bipyridine-based covalent organic framework catalytic material modified by iron single atom metal comprises the following steps:

[0083] 50 mg TB-COF and 50 mg ferric chloride (FeCl3) were added to a 100 mL round-bottom flask, and 30 mL of methanol was added to the flask as a solution. A corrosion-resistant stirring bar was added, and a condenser was added to the top of the round-bottom flask. The flask was placed in a water bath and stirred at 65°C for 6 hours. The obtained solid was washed with ethanol and pure water by centrifugation for 4 times, and dried at 80°C in a vacuum drying oven for 12 hours to obtain Fe-TB-COF, a bipyridine-based covalent organic framework catalytic material modified by iron single atom metal.

[0084] 5 mg of the Fe-TB-COF prepared above was added to the sulfamethoxazole solution and uniformly dispersed, and 0.5 mg of sodium chlorite was added to degrade the sulfamethoxazole in the water.

[0085] Example 6 A bimetallic atom-modified covalent organic framework catalytic material (FeMn-TB-COF) and its preparation method and application

[0086] The method for preparing the bipyridine-based covalent organic framework catalytic material modified with iron and manganese diatomic metals comprises the following steps:

[0087] 50mg TB-COF, 25mg ferric chloride (FeCl3), and 25mg manganese chloride (MnCl2) were added to a 100mL round-bottom flask, and 30mL methanol was added to the flask as a solution. A corrosion-resistant stirring bar was added, and a condenser was added to the top of the round-bottom flask. The flask was placed in a water bath and stirred at 65°C for 6h. The obtained solid was washed by centrifugation with ethanol and pure water for 4 times, and dried at 80°C in a vacuum drying oven for 12h to obtain FeMn-TB-COF, a bipyridine-based covalent organic framework catalytic material modified with iron and cobalt diatomic metals.

[0088] 5 mg of the FeMn-TB-COF prepared above was added to the sulfamethoxazole solution and uniformly dispersed, and 0.5 mg of sodium chlorite was added to degrade the sulfamethoxazole in the water.

[0089] Example 7 A bimetallic atom-modified covalent organic framework catalytic material (FeNi-TB-COF) and its preparation method and application

[0090] The method for preparing the bipyridine-based covalent organic framework catalytic material modified with iron and nickel diatomic metals comprises the following steps:

[0091] 50 mg TB-COF, 25 mg ferric chloride (FeCl3), and 25 mg nickel chloride (NiCl2) were added to a 100 mL round-bottom flask, and 30 mL methanol was added to the flask as a solution. A corrosion-resistant stirring bar was added, and a condenser was added to the top of the round-bottom flask. The flask was placed in a water bath and stirred at 65°C for 6 hours. The obtained solid was washed with ethanol and pure water by centrifugation for 4 times, and dried at 80°C in a vacuum drying oven for 12 hours to obtain FeNi-TB-COF, a bipyridine-based covalent organic framework catalytic material modified with iron and nickel diatomic metals.

[0092] 5 mg of the FeNi-TB-COF prepared above was added to the sulfamethoxazole solution and uniformly dispersed, and 0.5 mg of sodium chlorite was added to degrade the sulfamethoxazole in the water.

[0093] Example 8 A bimetallic atom-modified covalent organic framework catalytic material (CoMn-TB-COF) and its preparation method and application

[0094] The method for preparing the bipyridine-based covalent organic framework catalytic material modified with cobalt and manganese diatomic metals comprises the following steps:

[0095] 50mg TB-COF, 25mg cobalt chloride (CoCl2), and 25mg manganese chloride (MnCl2) were added to a 100mL round-bottom flask, and 30mL of methanol was added to the flask as a solution. A corrosion-resistant stirring bar was added, and a condenser was added to the top of the round-bottom flask. The flask was placed in a water bath and stirred at 65°C for 6h. The obtained solid was washed by centrifugation with ethanol and pure water for 4 times, and dried at 80°C in a vacuum drying oven for 12h to obtain the bipyridine-based covalent organic framework catalytic material CoMn-TB-COF modified with cobalt and manganese diatomic metals.

[0096] 5 mg of the CoMn-TB-COF prepared above was added to the sulfamethoxazole solution and uniformly dispersed, and 0.5 mg of sodium chlorite was added to degrade the sulfamethoxazole in the water.

[0097] Example 9 A bimetallic atom-modified covalent organic framework catalytic material (CoNi-TB-COF) and its preparation method and application

[0098] The method for preparing the bipyridine-based covalent organic framework catalytic material modified with cobalt and nickel diatomic metals comprises the following steps:

[0099] 50mg TB-COF, 25mg cobalt chloride (CoCl2), and 25mg nickel chloride (NiCl2) were added to a 100mL round-bottom flask, and 30mL of methanol was added to the flask as a solution. A corrosion-resistant stirring bar was added, and a condenser was added to the top of the round-bottom flask. The flask was placed in a water bath and stirred at 65°C for 6h. The obtained solid was washed by centrifugation with ethanol and pure water for 4 times, and dried at 80°C in a vacuum drying oven for 12h to obtain a bipyridine-based covalent organic framework catalytic material CoNi-TB-COF modified with cobalt and nickel diatomic metals.

[0100] 5 mg of the CoNi-TB-COF prepared above was added to the sulfamethoxazole solution and uniformly dispersed, and 0.5 mg of sodium chlorite was added to degrade the sulfamethoxazole in the water.

[0101] Example 10 A bimetallic atom-modified covalent organic framework catalytic material (MnNi-TB-COF) and its preparation method and application

[0102] The method for preparing the bipyridine-based covalent organic framework catalytic material modified with manganese and nickel diatomic metals comprises the following steps:

[0103] 50mg TB-COF, 25mg manganese chloride (MnCl2), and 25mg nickel chloride (NiCl2) were added to a 100mL round-bottom flask, and 30mL methanol was added to the flask as a solution. A corrosion-resistant stirring bar was added, and a condenser was added to the top of the round-bottom flask. The flask was placed in a water bath and stirred for 6 hours at 70°C. The obtained solid was washed by centrifugation with ethanol and pure water for 4 times, and dried at 80°C in a vacuum drying oven for 12 hours to obtain a bipyridine-based covalent organic framework catalytic material MnNi-TB-COF modified with manganese and nickel diatomic metals.

[0104] 5 mg of the MnNi-TB-COF prepared above was added to the sulfamethoxazole solution and uniformly dispersed, and 0.5 mg of sodium chlorite was added to degrade the sulfamethoxazole in the water.

[0105] Example 11 A single metal atom modified covalent organic framework catalytic material (Fe 0.25 -TB-COF) and its preparation method and application

[0106] The method for preparing the bipyridine-based covalent organic framework catalytic material modified by iron single atom metal comprises the following steps:

[0107] 50 mg TB-COF and 25 mg ferric chloride (FeCl3) were added to a 100 mL round-bottom flask, and 30 mL of methanol was added to the flask as a solution. A corrosion-resistant stirring rod was added, and a condenser was placed on the top of the round-bottom flask. The flask was placed in a water bath and stirred at 65°C for 6 hours. The obtained solid was washed with ethanol and pure water by centrifugation for 4 times, and dried at 80°C in a vacuum drying oven for 12 hours to obtain a bipyridine-based covalent organic framework catalytic material Fe modified by an iron single atom metal. 0.25 -TB-COF.

[0108] Take 5 mg of Fe prepared above 0.25 -TB-COF was added to the sulfamethoxazole solution and dispersed uniformly, and 0.5 mg of sodium chlorite was added to degrade sulfamethoxazole in the water.

[0109] Example 12 A single metal atom modified covalent organic framework catalytic material (Fe 0.75 -TB-COF) and its preparation method and application

[0110] The method for preparing the bipyridine-based covalent organic framework catalytic material modified by iron single atom metal comprises the following steps:

[0111] 50 mg TB-COF and 75 mg ferric chloride (FeCl3) were added to a 100 mL round-bottom flask, and 30 mL of methanol was added to the flask as a solution. A corrosion-resistant stirring rod was added, and a condenser was placed on the top of the round-bottom flask. The flask was placed in a water bath and stirred at 65 ° C for 6 hours. The obtained solid was washed with ethanol and pure water by centrifugation for 4 times, and dried at 80 ° C in a vacuum drying oven for 12 hours to obtain a bipyridine-based covalent organic framework catalytic material Fe modified by an iron single atom metal. 0.75 -TB-COF.

[0112] Take 5 mg of Fe prepared above 0.75 -TB-COF was added to the sulfamethoxazole solution and dispersed uniformly, and 0.5 mg of sodium chlorite was added to degrade sulfamethoxazole in the water.

[0113] Example 11 A single metal atom modified covalent organic framework catalytic material (Fe 1.00 -TB-COF) and its preparation method and application

[0114] The method for preparing the bipyridine-based covalent organic framework catalytic material modified by iron single atom metal comprises the following steps:

[0115] 50 mg TB-COF and 100 mg ferric chloride (FeCl3) were added to a 100 mL round-bottom flask, and 30 mL of methanol was added to the flask as a solution. A corrosion-resistant stirring rod was added, and a condenser was placed on the top of the round-bottom flask. The flask was placed in a water bath and stirred at 65 ° C for 6 hours. The obtained solid was washed with ethanol and pure water by centrifugation for 4 times, and dried in a vacuum drying oven at 80 ° C for 12 hours to obtain a single-atom metal-modified bipyridine-based covalent organic framework catalytic material Fe 1.00 -TB-COF.

[0116] Take 5 mg of Fe prepared above 1.00 -TB-COF was added to the sulfamethoxazole solution and dispersed uniformly, and 0.5 mg of sodium chlorite was added to degrade sulfamethoxazole in the water.

[0117] Example 14 A bimetallic atom-modified covalent organic framework catalytic material (FeCo-TB-COF) and its preparation method and application

[0118] The method for preparing the bipyridine-based covalent organic framework catalytic material modified with iron and cobalt diatomic metals comprises the following steps:

[0119] 50 mg TB-COF, 25 mg ferric chloride (FeCl3), and 25 mg cobalt chloride (CoCl2) were added to a 100 mL round-bottom flask, and 30 mL of methanol was added to the flask as a solution. A corrosion-resistant stirring bar was added, and a condenser was added to the top of the round-bottom flask. The flask was placed in a water bath and stirred at 65°C for 6 hours. The obtained solid was washed with ethanol and pure water by centrifugation for 4 times, and dried at 80°C in a vacuum drying oven for 12 hours to obtain FeCo-TB-COF, a bipyridine-based covalent organic framework catalytic material modified with iron and cobalt diatomic metals.

[0120] 5 mg of the FeCo-TB-COF prepared above was added to the acetaminophen solution and uniformly dispersed, and 0.5 mg of sodium chlorite was added to degrade acetaminophen in the water.

[0121] Example 15 A bimetallic atom-modified covalent organic framework catalytic material (FeCo-TB-COF) and its preparation method and application

[0122] The method for preparing the bipyridine-based covalent organic framework catalytic material modified with iron and cobalt diatomic metals comprises the following steps:

[0123] 50 mg TB-COF, 25 mg ferric chloride (FeCl3), and 25 mg cobalt chloride (CoCl2) were added to a 100 mL round-bottom flask, and 30 mL of methanol was added to the flask as a solution. A corrosion-resistant stirring bar was added, and a condenser was added to the top of the round-bottom flask. The flask was placed in a water bath and stirred at 65°C for 6 hours. The obtained solid was washed with ethanol and pure water by centrifugation for 4 times, and dried at 80°C in a vacuum drying oven for 12 hours to obtain FeCo-TB-COF, a bipyridine-based covalent organic framework catalytic material modified with iron and cobalt diatomic metals.

[0124] 5 mg of the FeCo-TB-COF prepared above was added to the bisphenol A solution and uniformly dispersed, and 0.5 mg of sodium chlorite was added to degrade bisphenol A in the water.

[0125] Example 16 A bimetallic atom-modified covalent organic framework catalytic material (FeCo-TB-COF) and its preparation method and application

[0126] The method for preparing the bipyridine-based covalent organic framework catalytic material modified with iron and cobalt diatomic metals comprises the following steps:

[0127] 50 mg TB-COF, 25 mg ferric chloride (FeCl3), and 25 mg cobalt chloride (CoCl2) were added to a 100 mL round-bottom flask, and 30 mL of methanol was added to the flask as a solution. A corrosion-resistant stirring bar was added, and a condenser was added to the top of the round-bottom flask. The flask was placed in a water bath and stirred at 65°C for 6 hours. The obtained solid was washed with ethanol and pure water by centrifugation for 4 times, and dried at 80°C in a vacuum drying oven for 12 hours to obtain FeCo-TB-COF, a bipyridine-based covalent organic framework catalytic material modified with iron and cobalt diatomic metals.

[0128] 5 mg of the FeCo-TB-COF prepared above was added to a p-nitrophenol solution and uniformly dispersed, and 0.5 mg of sodium chlorite was added to degrade p-nitrophenol in the water.

[0129] Example 17 A bimetallic atom-modified covalent organic framework catalytic material (FeCo-TB-COF) and its preparation method and application

[0130] The experimental scheme is the same as that of Example 1, except that the TB-COF used is TfpBpy-COF, and the preparation method is:

[0131] Weigh 63 mg of 2,4,6-triformylphloroglucinol and 83.7 mg of 5,5'-diamino-2,2'-bipyridine in a 15 mL internal threaded reaction bottle, add 4.5 mL of chromatographic grade N,N-dimethylacetamide and 1.5 mL of o-dichlorobenzene, mix well and quickly add 0.6 mL of 6M acetic acid solution, mix well, quickly freeze with liquid nitrogen, evacuate the internal pressure to vacuum, seal the reaction bottle, thaw and cycle liquid nitrogen freezing-vacuum degassing-thawing three times, and place the sealed reaction bottle at 120 ° C for 72 hours. After the reaction is completed, cool to room temperature, wash with analytically pure N,N-dimethylacetamide, dichloromethane, acetone, and methanol, and place the washed solid in a 150 ° C vacuum drying oven for activation for 12 hours. After cooling to room temperature, grind to obtain TfpBpy-COF. Comparative Example 1 Removal of Sulfamethoxazole by Chlorite

[0132] 0.5 mg of chlorite was added to 50 mL of sulfamethoxazole solution without catalytic material and stirred for 30 minutes.

[0133] Comparative Example 2 A covalent organic framework catalytic material (TB-COF) and its preparation method and application

[0134] 5 mg of the TB-COF prepared above was added to the sulfamethoxazole solution and uniformly dispersed, and 0.5 mg of sodium chlorite was added to degrade the sulfamethoxazole in the water.

[0135] Comparative Example 3 A diatomic metal modified covalent organic framework catalytic material (CuMg-TB-COF) and its preparation method and application

[0136] 50mg TB-COF, 25mg copper chloride (CuCl2), and 25mg magnesium chloride (MgCl2) were added to a 100mL round-bottom flask, and 30mL of methanol was added to the flask as a solution. A corrosion-resistant stirring bar was added, and a condenser was added to the top of the round-bottom flask. The flask was placed in a water bath and stirred for 6 hours at 75°C. The obtained solid was washed by centrifugation with ethanol and pure water for 4 times, and dried at 80°C in a vacuum drying oven for 12 hours to obtain CuMg-TB-COF, a bipyridine-based covalent organic framework catalytic material modified with copper and magnesium diatomic metals.

[0137] The performance test methods and experimental results of M-TB-COF of various embodiments and comparative examples of the present invention are as follows:

[0138] 1. X-ray diffraction (XRD) test

[0139] The FeCo-TB-COF material prepared in Example 1 was subjected to XRD test, and the obtained XRD spectrum is shown in Figure 3. As can be seen from the comparison in the figure, after metal loading treatment, no peaks related to metals or metal oxides appear in the XRD spectrum, and the metal is loaded on the covalent organic framework material in the form of single atoms. The peak at 2θ=3.67° corresponds to the (100) crystal plane, and the broad peak at 2θ=26° corresponds to the stacking at the (002) crystal plane. The above results prove that metal modification does not change the original structure of the covalent organic framework and maintains the integrity of the structure.

[0140] 2. Scanning electron microscope (SEM) test

[0141] The FeCo-TB-COF material prepared in Example 1 and the TB-COF material prepared in Example 1 were subjected to scanning electron microscopy (SEM) detection. Figure 1 , 2 As can be seen from the figure, the metal-loaded covalent organic framework materials prepared in Example 1 and Comparative Example 1 present a coral reef-like structure, and the linear structures intersect and tend to agglomerate into a spherical shape.

[0142] 3. Electron spin resonance (ESR) free radical capture test

[0143] In order to fully demonstrate the active oxygen species generated by the FeCo-TB-COF diatomic metal-modified bipyridyl-based covalent organic framework during the activation of chlorite, the FeCo-TB-COF material prepared in Example 1 was subjected to superoxide free radical capture experiments using a DMPO dimethyl sulfoxide solution, the FeCo-TB-COF material prepared in Example 1 was subjected to hydroxyl free radical capture experiments using a DMPO deionized water solution, and the FeCo-TB-COF material prepared in Example 1 was subjected to singlet oxygen capture experiments using a TEMP deionized water solution. The results are shown in Figure 4 , 5 As can be seen from the figure, the response signal of DMPO combining with hydroxyl radicals and the response signal of DMPO combining with superoxide radicals are generated in the catalytic system. This proves that the above-mentioned material system can generate hydroxyl radicals and superoxide radicals in the process of activating chlorite, which participate in the degradation of pollutants.

[0144] 4. UV-visible absorption spectrum test

[0145] The generation of ClO2 produced by the FeCo-TB-COF diatomic metal-modified bipyridyl covalent organic framework in the process of activating chlorite was fully demonstrated. 3 mL of the reaction solution at 0 min, 2 min, 5 min, 10 min, 20 min, 30 min, 45 min, and 60 min were taken, and the absorbance of the filtrate at 359 nm was tested after filtering through a 0.22 μm filter head. The results are shown in Figure 6 As can be seen from the figure, the absorbance at 359nm gradually increases in the catalytic system, indicating the generation of ClO2.

[0146] 5. Antibiotic degradation performance test

[0147] Take 50mL of 10mg / L pollutant solution in a 100mL beaker, add the M-TB-COF catalyst prepared in Experimental Examples 1 to 13, add Teflon wear-resistant stirring bar and stir at 500rpm for 30 minutes to make the catalyst disperse evenly in the pollutant solution and reach the adsorption equilibrium of the catalyst on the pollutant. Then add 0.5mg of sodium chlorite, take 2mL of the reaction solution at 0min, 2min, 5min, 10min, 15min, 20min, and 30min respectively, filter through a 0.22μm filter head and absorb 1mL of the filtrate, add 10μL of sodium thiosulfate solution to quench, mix well, measure the pollutant concentration in the sample by high performance liquid chromatography, and obtain the pollutant degradation effect curve. The test results are shown in Table 1.

[0148] Table 1 Experimental results of antibiotic degradation performance determination

[0149] Example / Comparative Example Antibiotic degradation rate (%) Example / Comparative Example Antibiotic degradation rate (%) Example 1 99.68 Embodiment 11 89.93 Example 2 90.15 Example 12 96.32 Example 3 82.69 Example 13 80.16 Example 4 75.36 Embodiment 14 99.35 Example 5 95.87 Embodiment 15 99.89 Example 6 94.85 Example 16 85.36 Example 7 92.69 Embodiment 17 83.68 Example 8 96.45 Comparative Example 1 3.78 Example 9 90.32 Comparative Example 2 21.85 Example 10 83.65 Comparative Example 3 48.95

[0150] As can be seen from Table 1, the degradation rate of pollutants in Comparative Examples 1 and 2 of the present invention is very low, indicating that single chlorite has no ability to remove pollutants, and the activation ability of the covalent organic framework without metal loading is also very limited for chlorite, with only a degradation rate of 21.85%. The diatomic metal-modified bipyridyl-based covalent organic framework catalytic materials and the single-atom metal-modified bipyridyl-based covalent organic framework catalytic materials prepared in Examples 1 to 13 of the present invention have good degradation effects on pollutants in water bodies, among which the pollutant degradation rate of Example 1 is as high as 99.68%. The comparison of Examples 2 to 5 proves that the different types of metal loadings of the catalyst can be simply regulated to achieve a better chlorite activation effect, among which the covalent organic framework material loaded with iron has the best catalytic performance. The comparison of Examples 1 and 6 to 10 proves that through the strategy of diatomic metal loading, the diatomic metal-modified bipyridyl-based covalent organic framework catalytic material can achieve a faster pollutant degradation effect. Comparison of Examples 10 to 12 explored the effects of different metal modification amounts of the catalyst on the performance of the catalyst. Within the appropriate loading range, as the amount of metal loaded on the covalent organic framework increases, the catalytic efficiency also increases. However, further increasing the mass ratio of the metal resulted in an increase in the degradation efficiency that then decreased. A lower metal loading will result in fewer reaction active sites and a poorer catalytic effect. Excessive metal loading will not significantly improve catalytic performance, resulting in a waste of raw materials and reduced cost-effectiveness. Excessive metal loading will lead to a decrease in catalytic performance. It may be that the metal forms atomic islands or metal clusters on the surface of the covalent organic framework, resulting in changes or shielding of active sites, inhibiting the activation of chlorite. The test results of the cyclic stability of chlorite catalyzed by Example 1 are shown in the figure. Figure 8 As shown, after five cycles, the removal rate of sulfamethoxazole (SMX) is still as high as 97.12%, which shows that the stability of the prepared material is very ideal. Comparative Examples 1, 14, 15, and 16, the prepared iron and cobalt diatomic metal modified bipyridine-based covalent organic framework catalytic material has excellent degradation performance for pollutants with high nucleophilic index such as sulfamethoxazole (SMX), acetaminophen (PCM), and bisphenol A (BPA) containing electron-donating groups, while the degradation performance of pollutants with high electrophilic index such as nitrophenol (NB) is slightly reduced, and the selective removal of pollutants can be achieved.

[0151] In Comparative Example 1, no catalytic material was added, and the antibiotic degradation rate was 3.78%, indicating the efficient degradation performance of the catalytic material provided by the present invention; in Comparative Example 2, no metal was loaded, and the activation ability of the catalyst for chlorite was very limited; in Comparative Example 3, copper and magnesium metals were loaded, and the effect was poor.

[0152] 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

1. A method for preparing a single / double metal atom modified covalent organic framework catalytic material, characterized in that: The following steps are involved: One or two metals selected from iron, manganese, cobalt or nickel are used to modify TB-COF by a solvothermal method to obtain M-TB-COF; The covalent organic framework TB-COF is synthesized using 1,3,5-triformylphloroglucinol and 2,2'-bipyridine-5,5'-diamine as precursors.

2. The preparation method according to claim 1, characterized in that: The metal is derived from a metal compound, and the mass ratio of the metal to TB-COF is 0.5 to 2.5:

1.

3. The preparation method according to claim 1, characterized in that: The solvent thermal method takes 6 to 8 hours.

4. The preparation method according to claim 1, characterized in that: The molar ratio of the 1,3,5-triformylphloroglucinol to the 2,2'-bipyridine-5,5'-diamine is 1:0.7-3.

5. The preparation method according to claim 1, characterized in that: The preparation method of the covalent organic framework TB-COF comprises the following steps: dissolving 1,3,5-triformylphloroglucinol and 2,2'-bipyridine-5,5'-diamine in an organic solvent, and reacting under acidic conditions to synthesize TB-COF.

6. The preparation method according to claim 5, characterized in that: The organic solvent is a mixed solution of dimethylacetamide and o-dichlorobenzene.

7. The preparation method according to claim 5, characterized in that: The acidic condition is adjusted with 4-8 M acetic acid.

8. A single / double metal atom modified covalent organic framework catalytic material, characterized in that: Prepared according to any one of claims 1 to 7.

9. Use of the covalent organic framework catalytic material modified with a single or double metal atom according to any one of claims 1 to 7 in treating micropollutants in water.

10. A method for degrading antibiotics in water, characterized in that: The following steps are involved: The single / double metal atom modified covalent organic framework catalytic material according to any one of claims 1 to 7 is added into water containing antibiotics, chlorite is added, and the reaction is stirred at 450 to 700 rpm.

Images