CN112958140A

CN112958140A - Co-PCN catalyst capable of regulating and controlling active site as well as preparation method and application thereof

Info

Publication number: CN112958140A
Application number: CN202110253342.4A
Authority: CN
Inventors: 李宁; 李�瑞; 陈冠益; 余洋; 颜蓓蓓; 宋英今
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2021-03-05
Filing date: 2021-03-05
Publication date: 2021-06-15
Anticipated expiration: 2041-03-05
Also published as: CN112958140B

Abstract

A Co-PCN catalyst capable of regulating and controlling an active site and a preparation method and application thereof are provided, the preparation method of the Co-PCN catalyst comprises the following steps: mixing a cobalt nitrate hexahydrate methanol solution with a 2-methylimidazole methanol solution to obtain a first mixed solution, and reacting the first mixed solution to obtain Co-ZIF-L; mixing the dopamine solution and the Co-ZIF-L dispersion liquid to obtain a second mixed solution, adjusting the pH value of the second mixed solution and reacting to obtain a Co-ZIF-L @ PDA composite material; and carrying out heat treatment on the Co-ZIF-L @ PDA composite material to obtain the Co-PCN catalyst. The invention reasonably regulates and controls the parameters of the preparation process, optimizes the crystal structure and the component composition, regulates the generation of active sites in the catalyst, promotes the release of active species in a PMS oxidation system, and solves the problem of low activity of the traditional PMS catalyst.

Description

Co-PCN catalyst capable of regulating and controlling active site as well as preparation method and application thereof

Technical Field

The invention belongs to the field of multifunctional water treatment and purification materials, and particularly relates to a Co-PCN catalyst with adjustable and controllable active sites, and a preparation method and application thereof.

Background

The antibiotics are widely used and are used in large amounts, a large amount of antibiotics directly or indirectly enter the environment in production and use links, and the existence of the antibiotics is detected in natural water bodies in various regions of the world, so that potential hazards are caused to the ecological environment and human health. Among the novel water pollutant removal technologies, Peroxymonosulfate (PMS) oxidation has become a research hotspot in the field of water pollution treatment due to the advantages of strong oxidation capacity, wide water quality application range, convenience in medicament transportation and the like.

The active sites in the catalyst influence the formation of active species in the system, and are particularly important for the efficient removal of water antibiotics. It is reported that divalent cobalt ion (Co)²⁺) Hydroxyl (-OH) is favorable for generating sulfate radical (SO)₄ ^-H) and hydroxyl radical (. OH), a radical-dominated reaction is more likely to occur; and carbonyl (C ═ O) and graphite nitrogen favor singlet oxygen (C ═ O)¹O₂) The formation of (a) is more likely to occur in reactions that are not radical dominated. By regulating and controlling the active sites in the catalyst, the persulfate oxidation system can remove pollutants more efficiently and stably. However, the directional regulation of the active site of the catalyst in a PMS system is not available at present, so that the improvement of the catalytic activity of the catalyst is limited, and the method becomes a main obstacle of practical water treatment application.

Disclosure of Invention

In view of the above, one of the main objectives of the present invention is to provide a Co-PCN catalyst with adjustable active sites, and a preparation method and applications thereof, so as to at least partially solve at least one of the above technical problems.

In order to achieve the above objects, as one aspect of the present invention, there is provided a method for preparing a Co-PCN catalyst with adjustable active sites, comprising:

(1) mixing a cobalt nitrate hexahydrate methanol solution with a 2-methylimidazole methanol solution to obtain a first mixed solution, and reacting the first mixed solution to obtain Co-ZIF-L;

(2) mixing the dopamine solution and the Co-ZIF-L dispersion liquid to obtain a second mixed solution, adjusting the pH value of the second mixed solution and reacting to obtain a Co-ZIF-L @ PDA composite material;

(3) and carrying out heat treatment on the Co-ZIF-L @ PDA composite material to obtain the Co-PCN catalyst.

As another aspect of the invention, the invention also provides a Co-PCN catalyst which is obtained by adopting the preparation method.

As a further aspect of the invention, the application of the Co-PCN catalyst obtained by the preparation method or the Co-PCN catalyst in the field of catalysis is also provided.

As still another aspect of the present invention, there is also provided a degradation method for degrading an antibiotic, comprising:

s1, adding the Co-PCN catalyst into the antibiotic pollutant solution to be treated to obtain a pollutant solution, and stirring the pollutant solution;

s2, adding PMS oxidant into the pollutant solution II obtained in the step S1, and stirring to complete degradation of the antibiotic pollutants.

Based on the technical scheme, compared with the prior art, the Co-PCN catalyst with the adjustable active site and the preparation method and the application thereof have at least one or part of the following advantages:

1. the invention provides a preparation method of a high-activity PMS system catalyst and strengthens the oxidation degradation of antibiotic pollutants by PMS; by reasonably regulating and controlling parameters (such as dopamine concentration, pyrolysis temperature and the like) in the preparation process, the crystal structure and the component composition are optimized, the generation of active sites in the catalyst is regulated, and the release of active species in a PMS oxidation system is promoted;

2. the specific surface area of the Co-PCN nano catalyst is about 6.5 times of that of a Co-ZIF-L precursor, and the number and the types of active sites of Co-PCN derived in situ from Co-ZIF-L are obviously increased;

3. under the action of PMS, the removal rate of the Co-PCN prepared by the method for 20min on antibiotic pollutants reaches 90%; continuous degradation experiments show that the nano catalyst has certain stability.

Drawings

Fig. 1 is an XPS peak profile of C element in x-Co-PCN (x 600, 700, 800, 900) in an example of the present invention;

fig. 2 is an XPS peak profile of N element in x-Co-PCN (x 600, 700, 800, 900) in the example of the present invention;

fig. 3 is an XPS peak profile of O element in x-Co-PCN (x 600, 700, 800, 900) in the example of the present invention;

fig. 4 is an XPS peak profile of Co element in x-Co-PCN (x 600, 700, 800, 900) according to an embodiment of the present invention;

FIG. 5 is a graph of the reaction rate constants for 10min of the catalyzed reaction of x-Co-PCN with ciprofloxacin antibiotic in one to three embodiments of the present invention;

FIG. 6 is a graph of the cyclic degradation rate of ciprofloxacin by the 900-Co-PCN catalyst in the PMS oxidation system in the example of the invention.

Detailed Description

In order that the objects, technical solutions and advantages of the present invention will become more apparent, the present invention will be further described in detail with reference to the accompanying drawings in conjunction with the following specific embodiments.

The invention discloses a preparation method of a Co-PCN catalyst, which comprises the following steps:

In some embodiments of the invention, in the step (1), the concentration of the cobalt nitrate hexahydrate in the first mixed solution is 5-15 g/L, such as 5g/L, 6g/L, 7g/L, 8g/L, 9g/L, 10g/L, 11g/L, 12g/L, 13g/L, 14g/L, 15 g/L;

in some embodiments of the invention, in step (1), the concentration of 2-methylimidazole in the first mixed solution is 10-25 g/L, for example, 10g/L, 11g/L, 12g/L, 13g/L, 14g/L, 15g/L, 16g/L, 17g/L, 18g/L, 19g/L, 20g/L, 21g/L, 22g/L, 23g/L, 24g/L, 25 g/L.

In some embodiments of the invention, in the step (2), the concentration of the dopamine solution in the second mixed solution is 0.1-3 g/L, such as 0.1g/L, 0.2g/L, 0.4g/L, 0.6g/L, 0.8g/L, 1.0g/L, 1.2g/L, 1.4g/L, 1.6g/L, 2.0g/L, 2.4g/L, 2.8g/L, 3 g/L;

in some embodiments of the invention, in the step (2), the concentration of the Co-ZIF-L in the second mixed solution is 10-30 g/L, for example, 10g/L, 11g/L, 12g/L, 13g/L, 14g/L, 15g/L, 17.5g/L, 20g/L, 22.5g/L, 25g/L, 27.5g/L, 30 g/L.

In some embodiments of the invention, in the step (2), the pH of the second mixed solution is adjusted to 6 to 10, for example, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10.

In some embodiments of the invention, in step (3), the heat treating step comprises:

heating the Co-ZIF-L @ PDA composite material to a first temperature within a first time, heating to a second temperature within a second time, maintaining for a period of time, and cooling to obtain a Co-PCN catalyst;

in some embodiments of the present invention, the first time is 10-30 min, such as 10min, 15min, 20min, 25min, 30 min;

in some embodiments of the invention, the first temperature is 100 to 300 ℃, such as 100 ℃, 120 ℃, 150 ℃, 180 ℃, 200 ℃, 220 ℃, 250 ℃, 280 ℃, 300 ℃;

in some embodiments of the invention, the second time is 40-70 min, such as 40min, 50min, 60min, 70 min;

in some embodiments of the invention, the second temperature is 600-900 deg.C, such as 600 deg.C, 620 deg.C, 650 deg.C, 680 deg.C, 700 deg.C, 720 deg.C, 750 deg.C, 780 deg.C, 800 deg.C, 820 deg.C, 850 deg.C, 880 deg.C, 900 deg.C;

in some embodiments of the present invention, the maintaining time is 1 to 3 hours.

The invention also discloses a Co-PCN catalyst which is prepared by the preparation method.

The invention also discloses the application of the Co-PCN catalyst obtained by the preparation method or the Co-PCN catalyst in the field of catalysis.

The invention discloses a degradation method for degrading antibiotics by PMS, which comprises the following steps:

In some embodiments of the invention, in step S1, the concentration of the Co-PCN catalyst in the first contaminant solution is 0.01-0.5 g/L, such as 0.01g/L, 0.02g/L, 0.05g/L, 0.08g/L, 0.1g/L, 0.2g/L, 0.3g/L, 0.4g/L, 0.5 g/L;

in some embodiments of the invention, in step S1, the solution one is stirred at room temperature for 30-90 min, such as 30min, 40min, 50min, 60min, 70min, 80min, 90 min; the stirring speed is 150-300r/min, such as 150r/min, 180r/min, 200r/min, 220r/min, 250r/min, 280r/min, 300 r/min.

In some embodiments of the invention, in step S2, the concentration of PMS oxidizer in the second contaminant solution is 0.1-6 mM, such as 0.1mM, 0.2mM, 0.3mM, 0.4mM, 0.5mM, 0.6mM, 0.8mM, 0.9mM, 1mM, 2mM, 3mM, 4mM, 5mM, 6 mM;

in some embodiments of the present invention, in step S2, the degradation time is 1-60 min, such as 1min, 2min, 5min, 6min, 7min, 8min, 10min, 20min, 30min, 40min, 50min, 60 min.

In an exemplary embodiment, poly-dopamine (PDA) is coated on the surface of a cobalt-containing metal framework material (Co-ZIF-L), a Co-ZIF-L precursor in-situ derived cobalt-nitrogen-carbon composite material (Co-PCN) is prepared through pyrolysis, and the Co-ZIF-L precursor in-situ derived cobalt-nitrogen-carbon composite material is applied to catalytic degradation of antibiotic organic pollutants under the oxidation action of PMS. The method comprises the following specific steps:

firstly, preparing a Co-ZIF-L precursor: dissolving cobalt nitrate hexahydrate in 150mL of anhydrous methanol to obtain a 10-30 g/L cobalt nitrate hexahydrate methanol solution. Dissolving 2-methylimidazole in 150mL of anhydrous methanol to obtain 20-50 g/L2-methylimidazole methanol solution. Transferring the 2-methylimidazole methanol solution into cobalt nitrate hexahydrate methanol solution to obtain 300mL of mixed solution, stirring at room temperature (for example, 10-30 ℃) for 10-60 min, standing for 3-24h, and forming purple crystals by a liquid phase diffusion method. And pouring out the supernatant, centrifuging the suspension at a rotating speed of 2000-10000 r/min for 3-10min, washing the suspension for 3-5 times by using absolute ethyl alcohol and deionized water respectively to remove organic and inorganic impurities remained on the surface of the precipitate, then placing the precipitate in a blast drying oven at 60-80 ℃ for 3-24h for drying, and finally grinding the Co-ZIF-L solid by using an agate mortar.

Secondly, preparing a Co-ZIF-L @ PDA composite material: preparing 100mL of 1-3 g/L Tris (hydroxymethyl) aminomethane (Tris) aqueous solution in deionized water, and dropwise adding dilute hydrochloric acid to adjust the pH value to 6-10 to obtain a Tris-HCl solution. Adding 100-300mg dopamine hydrochloride into the Tris-HCl solution, and stirring for 3-10min to obtain the dopamine solution. Adding 0.1-1 g of Co-ZIF-L precursor powder into 40mL of dopamine solution, dropwise adding ammonia water to adjust the pH value to 6-10, enabling dopamine to perform polymerization reaction on the surface of Co-ZIF-L to form a polydopamine shell, and stirring at room temperature for 1-3 hours. And then centrifuging to obtain a solid suspended substance, respectively washing with absolute ethyl alcohol and deionized water for three times, placing in a 60-80 ℃ forced air drying oven for 3-24h for drying, and finally grinding the Co-ZIF-L @ PDA core-shell structure solid.

Thirdly, regulating and controlling active sites in Co-PCN: and (3) raising the temperature of Co-ZIF-L @ PDA to 100-300 ℃ from room temperature in a tube furnace within 10-30 min, and preheating the equipment to stabilize the equipment so that all the catalysts are pyrolyzed at the same temperature raising rate in the second stage. And then heating from 100-300 ℃ to 600-900 ℃ within 40-70 min, maintaining for 1-3 h, and cooling to obtain the Co-PCN nano material, namely the catalyst for regulating the active sites by controlling the pyrolysis temperature.

Fourthly, a method for degrading antibiotic pollutants by a PMS oxidation system is suitable for removing organic micropollutants in a water body, and comprises the following specific steps:

adding 0.001-0.1 g of Co-PCN catalyst into 100-200 mL of pollutant solution, carrying out 100W ultrasonic treatment for 1-3 min, stirring the mixed solution at room temperature (300r/min) for 1-30 min, taking 1mL of suspension by using an injector, filtering by using a 0.22 mu m filter membrane, and determining the concentration of the pollutant in the sample by using high performance liquid chromatography.

The technical solution of the present invention is further illustrated by the following specific embodiments in conjunction with the accompanying drawings. It should be noted that the following specific examples are given by way of illustration only and the scope of the present invention is not limited thereto.

The chemicals and raw materials used in the following examples were either commercially available or self-prepared by a known preparation method.

Example 1

The application of the method for regulating and controlling the activation of the active site reinforced PMS in the Co-PCN catalyst is carried out by the following steps:

firstly, preparing a Co-ZIF-L precursor: cobalt nitrate hexahydrate is dissolved in 150mL of anhydrous methanol to obtain a methanol solution of cobalt nitrate hexahydrate. 2-methylimidazole was dissolved in 150mL of anhydrous methanol to obtain a 2-methylimidazole methanol solution. Transferring the 2-methylimidazole methanol solution into cobalt nitrate hexahydrate methanol solution to obtain 300mL of mixed solution, stirring at room temperature for 30min, and standing for 12 h. And (3) pouring out the supernatant, centrifuging the suspension for 5min at the rotating speed of 4000r/min, respectively washing the suspension for 3 times by using absolute ethyl alcohol and deionized water, then placing the suspension in a blast drying oven at the temperature of 60 ℃ for 12h for drying, and finally grinding the Co-ZIF-L solid by using an agate mortar.

Secondly, preparing a Co-ZIF-L @ PDA composite material: 100mL of 1.2g/L Tris (hydroxymethyl) aminomethane (Tris) aqueous solution is prepared in deionized water, and diluted hydrochloric acid is dripped to adjust the pH value to 8.5, so as to obtain a Tris-HCl solution. Adding 160mg of dopamine hydrochloride into the Tris-HCl solution, and stirring for 5min to obtain a dopamine solution. Adding 0.5g of Co-ZIF-L precursor powder into 40mL of dopamine solution, dropwise adding ammonia water to adjust the pH value to 8.5, and stirring at room temperature for 2 h. And then centrifuging to obtain a solid suspended substance, washing with absolute ethyl alcohol and deionized water for three times respectively, placing in a 60 ℃ forced air drying oven for 12 hours for drying, and finally grinding the Co-ZIF-L @ PDA solid.

Thirdly, preparing 600-Co-PCN: respectively heating Co-ZIF-L @ PDA in a tube furnace from room temperature to 200 ℃ within 20 minutes, respectively heating from 200 ℃ to 600 ℃ within 40 minutes, maintaining for 2 hours, and cooling to obtain 600-Co-PCN.

Fourthly, preparation of 900-Co-PCN: respectively heating Co-ZIF-L @ PDA in a tube furnace from room temperature to 200 ℃ within 20 minutes, respectively heating from 200 ℃ to 900 within 70 minutes, maintaining for 2 hours, and cooling to obtain 900-Co-PCN.

And fifthly, respectively adding 0.01g of 600-Co-PCN catalyst and 900-Co-PCN catalyst into 100mL of ciprofloxacin solution (15mg/L), carrying out 100W ultrasonic treatment for 1min, stirring the mixed solution (150r/min) at room temperature for 30min, immediately adding 100 mu L of PMS (0.6M), continuing stirring for 20min, taking 1mL of suspension by using a syringe, filtering by using a 0.22 mu M filter membrane, and determining the concentration of pollutants in the sample by using high performance liquid chromatography.

The 600-Co-PCN and 900-Co-PCN prepared above were subjected to characterization and performance tests, as shown in FIGS. 1 to 6, and the results were as follows:

XPS test results show that the graphite nitrogen active site contents of 600-Co-PCN and 900-Co-PCN in the N1 s peak separating result are respectively 13.50% and 45.84%, the-OH active site contents of 600-Co-PCN and 900-Co-PCN in the O1 s peak separating result are respectively 19.77% and 48.54%, the C ═ O active site contents of 600-Co-PCN and 900-Co-PCN in the C1 s peak separating result are respectively 8.00% and 5.97%, and the Co-Nx active site contents of 600-Co-PCN and 900-Co-PCN in the Co 2p3/2 peak separating result are respectively 52.47% and 45.76%. When the pyrolysis temperature is 900 ℃, the content of graphite nitrogen and-OH is increased, and the content of C ═ O and Co-Nx is reduced, compared with the pyrolysis temperature of 600 ℃.

The ciprofloxacin degradation experiment result shows that after the 600-Co-PCN and the 900-Co-PCN are catalyzed, oxidized and degraded for 20min, the removal rates of ciprofloxacin in the pollutant solution II are respectively 41% and 90%, and the pyrolysis temperature rise of Co-ZIF-L @ PDA is favorable for degrading antibiotic pollutants.

The results of the free radical quenching experiments show that excessive anhydrous formazan is respectively added into the pollutant solution IIWhen alcohol tert-butyl alcohol and L-histidine are adopted, the reaction rate constants in a 600-Co-PCN/PMS catalytic system are 0.02996 +/-0.00127, 0.05591 +/-0.00972 and 0.04806 +/-0.00885 min^-1And the reaction rate constants in the 900-Co-PCN/PMS catalytic system are 0.06658 +/-0.01382, 0.22218 +/-0.01146 and 0.01329 +/-0.00135 min respectively^-1It is shown that 600-Co-PCN has a higher reaction rate for degrading contaminants through a free radical reaction pathway than 900-Co-PCN, and a lower reaction rate for degrading contaminants through a non-free radical reaction pathway.

Example 2

firstly, preparing a Co-ZIF-L precursor: cobalt nitrate hexahydrate is dissolved in 150mL of anhydrous methanol to obtain a methanol solution of cobalt nitrate hexahydrate. 2-methylimidazole was dissolved in 150mL of anhydrous methanol to obtain a 2-methylimidazole methanol solution. Transferring the 2-methylimidazole methanol solution into cobalt nitrate hexahydrate methanol solution to obtain 300mL of mixed solution, stirring at room temperature for 30min, and standing for 12 h. And pouring out the supernatant, centrifuging the suspension at the rotating speed of 2000r/min for 10min, respectively washing the suspension for 3 times by using absolute ethyl alcohol and deionized water, then placing the suspension in a forced air drying oven at the temperature of 80 ℃ for 6h for drying, and finally grinding the Co-ZIF-L solid by using an agate mortar.

Secondly, preparing a Co-ZIF-L @ PDA composite material: 100mL of 1.2g/L Tris (hydroxymethyl) aminomethane (Tris) aqueous solution is prepared in deionized water, and diluted hydrochloric acid is dripped to adjust the pH value to 8.5, so as to obtain a Tris-HCl solution. Adding 160mg of dopamine hydrochloride into the Tris-HCl solution, and stirring for 3min to obtain a dopamine solution. Adding 0.5g of Co-ZIF-L precursor powder into 40mL of dopamine solution, dropwise adding ammonia water to adjust the pH value to 8.5, and stirring at room temperature for 2 h. And then centrifuging to obtain a solid suspended substance, washing with absolute ethyl alcohol and deionized water for three times respectively, placing in a forced air drying oven at 80 ℃ for 6h for drying, and finally grinding the Co-ZIF-L @ PDA solid.

Thirdly, preparing 700-Co-PCN: respectively heating Co-ZIF-L @ PDA in a tube furnace from room temperature to 200 ℃ within 20 minutes, respectively heating from 200 ℃ to 700 ℃ within 50 minutes, maintaining for 2 hours, and cooling to obtain 700-Co-PCN.

And fifthly, respectively adding 0.01g of 700-Co-PCN catalyst and 900-Co-PCN catalyst into 100mL of ciprofloxacin solution (15mg/L), carrying out 100W ultrasonic treatment for 1min, stirring the mixed solution at room temperature (200r/min) for 60min, immediately adding 100 mu L of PMS (0.6M), continuing stirring for 20min, taking 1mL of suspension by using a syringe, filtering by using a 0.22 mu M filter membrane, and determining the concentration of pollutants in the sample by using high performance liquid chromatography.

The 700-Co-PCN and 900-Co-PCN prepared above were subjected to characterization and performance tests, as shown in FIGS. 1 to 6, and the results were as follows:

the XPS test result shows that the graphite nitrogen active site contents of 700-Co-PCN and 900-Co-PCN in the N1 s peak separating result are respectively 26.62% and 45.84%, the-OH active site contents of 700-Co-PCN and 900-Co-PCN in the O1 s peak separating result are respectively 28.57% and 48.54%, the C ═ O active site contents of 700-Co-PCN and 900-Co-PCN in the C1 s peak separating result are respectively 7.71% and 5.97%, and the Co-Nx active site contents of 700-Co-PCN and 900-Co-PCN in the Co 2p3/2 peak separating result are respectively 51.48% and 45.76%. When the pyrolysis temperature is 900 ℃, the content of graphite nitrogen and-OH is increased, and the content of C ═ O and Co-Nx is reduced, compared with the pyrolysis temperature of 700 ℃.

The ciprofloxacin degradation experiment result shows that after 700-Co-PCN and 900-Co-PCN are catalyzed, oxidized and degraded for 20min, the removal rates of ciprofloxacin in the pollutant solution II are respectively 60% and 90%, and the pyrolysis temperature rise of Co-ZIF-L @ PDA is beneficial to the degradation of antibiotic pollutants.

The results of free radical quenching experiments show that when excessive absolute methanol tert-butyl alcohol and excessive L-histidine are respectively added into the pollutant solution II, the reaction rate constants in the 700-Co-PCN/PMS catalytic system are 0.04088 +/-0.00377, 0.1212 +/-0.00872 and 0.04236 +/-0.00481 min^-1And the reaction rate constants in the 900-Co-PCN/PMS catalytic system are 0.06658 +/-0.01382, 0.22218 +/-0.01146 and 0.01329 +/-0.00135 min respectively^-1It is shown that 700-Co-PCN has a higher reaction rate for degrading contaminants through a free radical reaction pathway than 900-Co-PCN, and a lower reaction rate for degrading contaminants through a non-free radical reaction pathway.

Example 3

firstly, preparing a Co-ZIF-L precursor: cobalt nitrate hexahydrate is dissolved in 150mL of anhydrous methanol to obtain a methanol solution of cobalt nitrate hexahydrate. 2-methylimidazole was dissolved in 150mL of anhydrous methanol to obtain a 2-methylimidazole methanol solution. Transferring the 2-methylimidazole methanol solution into cobalt nitrate hexahydrate methanol solution to obtain 300mL of mixed solution, stirring at room temperature for 30min, and standing for 24 h. And (3) pouring out the supernatant, centrifuging the suspension for 3min at the rotating speed of 10000r/min, respectively washing the suspension for 3 times by using absolute ethyl alcohol and deionized water, then placing the suspension in a forced air drying oven at 70 ℃ for 24h for drying, and finally grinding the Co-ZIF-L solid by using an agate mortar.

Secondly, preparing a Co-ZIF-L @ PDA composite material: 100mL of 1.2g/L Tris (hydroxymethyl) aminomethane (Tris) aqueous solution is prepared in deionized water, and diluted hydrochloric acid is dripped to adjust the pH value to 8.5, so as to obtain a Tris-HCl solution. Adding 160mg of dopamine hydrochloride into the Tris-HCl solution, and stirring for 5min to obtain a dopamine solution. Adding 0.5g of Co-ZIF-L precursor powder into 40mL of dopamine solution, dropwise adding ammonia water to adjust the pH value to 8.5, and stirring at room temperature for 2 h. And then centrifuging to obtain a solid suspended substance, washing with absolute ethyl alcohol and deionized water for three times respectively, placing in a forced air drying oven at 70 ℃ for 24h for drying, and finally grinding the Co-ZIF-L @ PDA solid.

Thirdly, preparing 800-Co-PCN: respectively heating Co-ZIF-L @ PDA in a tube furnace from room temperature to 200 ℃ within 20 minutes, respectively heating from 200 ℃ to 800 ℃ within 60 minutes, maintaining for 2 hours, and cooling to obtain 800-Co-PCN.

And fifthly, respectively adding 0.01g of 800-Co-PCN catalyst and 900-Co-PCN catalyst into 100mL of ciprofloxacin solution (15mg/L), carrying out 100W ultrasonic treatment for 1min, stirring the mixed solution (300r/min) at room temperature for 90min, immediately adding 100 mu L of PMS (0.6M), continuing stirring for 20min, taking 1mL of suspension by using an injector, filtering by using a 0.22 mu M filter membrane, and measuring the concentration of pollutants in the sample by using high performance liquid chromatography.

The 800-Co-PCN and 900-Co-PCN prepared above were subjected to characterization and performance tests, as shown in FIGS. 1 to 6, and the results were as follows:

XPS test results show that the graphite nitrogen active site contents of 800-Co-PCN and 900-Co-PCN in the N1 s peak separation result are 33.93% and 45.84% respectively, the-OH active site contents of 800-Co-PCN and 900-Co-PCN in the O1 s peak separation result are 25.33% and 48.54% respectively, the C ═ O active site contents of 800-Co-PCN and 900-Co-PCN in the C1 s peak separation result are 9.02% and 5.97% respectively, and the Co-Nx active site contents of 800-Co-PCN and 900-Co-PCN in the Co 2p3/2 peak separation result are 46.91% and 45.76% respectively. When the pyrolysis temperature is 900 ℃, the content of graphite nitrogen and-OH is increased, and the content of C ═ O and Co-Nx is reduced, compared with the pyrolysis temperature of 800 ℃.

The ciprofloxacin degradation experiment result shows that after the 800-Co-PCN and the 900-Co-PCN are catalyzed, oxidized and degraded for 20min, the removal rates of ciprofloxacin in the pollutant solution II are respectively 79% and 90%, and the pyrolysis temperature rise of Co-ZIF-L @ PDA is favorable for degrading antibiotic pollutants.

The results of free radical quenching experiments show that when excessive absolute methanol tert-butyl alcohol and excessive absolute methanol L-histidine are respectively added into the pollutant solution II, the reaction rate constants in the 800-Co-PCN/PMS catalytic system are 0.06048 +/-0.00129, 0.2083 +/-0.0181 and 0.02653 +/-0.00361 min^-1And the reaction rate constants in the 900-Co-PCN/PMS catalytic system are 0.06658 +/-0.01382, 0.22218 +/-0.01146 and 0.01329 +/-0.00135 min respectively^-1It is shown that 800-Co-PCN has a higher reaction rate for degrading contaminants through a free radical reaction pathway and a lower reaction rate for degrading contaminants through a non-free radical reaction pathway than 900-Co-PCN.

Fig. 1 to 4 are peak profiles of XPS results of C, N, O, Co elements in x-Co-PCN (x ═ 600, 700, 800, 900), respectively, where the content changes of graphite nitrogen and — OH active sites integrally show an upward trend with the increase of pyrolysis temperature, and the content changes of C ═ O and Co-Nx active sites integrally show a downward trend with the increase of pyrolysis temperature, indicating that the pyrolysis temperature can effectively regulate and control the active sites in the Co-ZIF-L in-situ derived cobalt-carbon-nitrogen composite material;

FIG. 5 is a graph of the degradation reaction rate constant of ciprofloxacin in a PMS system radical quenching experiment of x-Co-PCN. Excess SO in anhydrous methanol system₄ ^-And OH free radical, tert-butanol and L-histidine quench So in the system respectively₄ ^-And¹o₂. When methanol and tert-butyl alcohol are used as quenchers, the degradation reaction rate constant is increased along with the increase of the pyrolysis temperature; when L-histidine is used as a quenching agent, the degradation reaction rate constant is reduced along with the increase of the pyrolysis temperature, which shows that the pyrolysis temperature of the catalyst can regulate and control the formation of active sites indicated by the catalyst, the generation condition of active species in a PMS oxidation system is regulated, and the degradation reaction rate is influenced.

FIG. 6 is a graph of the cyclic degradation rate of ciprofloxacin by a 900-Co-PCN catalyst in a PMS oxidation system. Through 3 times of cyclic degradation experiments, the removal rate of the ciprofloxacin is reduced by less than 5 percent, which shows that the ciprofloxacin has stronger stability in a PMS oxidation system.

Comparative example 1

Adding Co-PCN catalyst and PMS oxidant simultaneously:

adding 0.01g of 900-Co-PCN catalyst into 100mL of ciprofloxacin solution (15mg/L), carrying out ultrasonic treatment for 1min by 100W, stirring the mixed solution at room temperature (300r/min) for 90min, immediately adding 100 mu L of PMS (0.6M), continuing stirring for 20min, taking 1mL of suspension by using a syringe, filtering by using a 0.22 mu M filter membrane, and determining the concentration of pollutants in a sample by using high performance liquid chromatography. The removal of contaminants was calculated to be 90%.

Addition of Co-PCN catalyst alone:

adding 0.01g of 900-Co-PCN catalyst into 100mL of ciprofloxacin solution (15mg/L), carrying out ultrasonic treatment for 1min by 100W, stirring the mixed solution at room temperature (300r/min) for 90min, immediately adding 100 mu L of water, continuing stirring for 20min, taking 1mL of suspension by using a syringe, filtering by using a 0.22 mu m filter membrane, and determining the concentration of pollutants in a sample by using high performance liquid chromatography. The removal of contaminants was calculated to be 15%.

Addition of PMS oxidant alone:

100mL of ciprofloxacin solution (15mg/L) was subjected to 100W ultrasonic treatment for 1min, the mixed solution was stirred at room temperature (300r/min) for 90min, 100. mu.L of PMS (0.6M) was immediately added, stirring was continued for 20min, 1mL of the suspension was taken out with a syringe and filtered through a 0.22. mu.m filter, and the concentration of contaminants in the sample was measured by high performance liquid chromatography. The removal of contaminants was calculated to be 3.48%.

The experiments show that the Co-PCN catalyst and the PMS oxidant play a synergistic role in degrading pollutants, and the Co-PCN catalyst activates the PMS to release active species, so that the oxidation reaction is promoted, and the content of the pollutants is greatly reduced.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A preparation method of a Co-PCN catalyst comprises the following steps:

2. The production method according to claim 1,

in the step (1), the concentration of cobalt nitrate hexahydrate in the first mixed solution is 5-15 g/L;

in the step (1), the concentration of the 2-methylimidazole in the first mixed solution is 10-25 g/L.

3. The production method according to claim 1,

in the step (2), the concentration of the dopamine solution in the second mixed solution is 0.1-3 g/L;

in the step (2), the concentration of Co-ZIF-L in the second mixed solution is 10-30 g/L.

4. The production method according to claim 1,

in the step (2), the pH value of the second mixed solution is adjusted to 6-10.

5. The production method according to claim 1,

in the step (3), the heat treatment step includes:

wherein the first time is 10-30 min; the first temperature is 100-300 ℃;

wherein the second time is 40-70 min; the second temperature is 600-900 ℃;

wherein the maintaining time is 1-3 h.

6. A Co-PCN catalyst obtained by the production method according to any one of claims 1 to 5.

7. Use of the Co-PCN catalyst obtained by the preparation process according to any of claims 1 to 5 or the Co-PCN catalyst according to claim 6 in the field of catalysis.

8. A degradation method for PMS degradation of antibiotics, comprising:

s1, adding the Co-PCN catalyst of claim 6 into the antibiotic pollutant solution to be treated to obtain a pollutant solution, and stirring the pollutant solution;

9. The degradation method according to claim 8,

in the step S1, the concentration of the Co-PCN catalyst in the pollutant solution I is 0.01-0.5 g/L;

in the step S1, stirring the solution I at room temperature for 30-90 min; the stirring speed is 150-300 r/min.

10. The degradation method according to claim 8,

in the step S2, the concentration of PMS oxidant in the pollutant solution II is 0.1-6 mM;

in step S2, the degradation time is 1-60 min.