Polytriazine imide / zinc ferrite photocatalytic composite material, preparation and application thereof

Abstract

The application discloses a preparation method and application of a polytriazimide / zinc ferrite photocatalytic composite material, and the composite material adopts a low-temperature molten salt method to prepare a high-crystallinity polytriazimide hexagonal prism as a structural reference; then zinc ferrite nanoparticles are in-situ grown on the surface of the hexagonal prism. The application in-situ grows visible light response semiconductor zinc ferrite nanoparticles on the surface of a polytriazimide hexagonal prism photocatalytic material for the first time; by constructing an organic / inorganic heterostructure, the defects of low utilization rate of visible light of the polytriazimide and acceleration of photogenerated carrier separation of a single-component material can be effectively solved, so that the overall photocatalytic activity of the composite material is improved. The photocatalytic composite material can be directly applied to removal of pathogenic microorganisms and organic antibiotic pollutants in water under visible light irradiation, and has great application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of functional nanomaterial preparation, solar energy utilization and environmental protection, and relates to a polytriazimide / zinc ferrite photocatalytic composite material and a preparation method thereof. BACKGROUND

[0002] The increasingly serious water pollution problem seriously affects the sustainable development of human beings and nature. Traditional water purification and disinfection methods such as chlorination and Fenton method usually have problems such as easy secondary pollution, high energy consumption, or slow reaction rate. In recent years, solar photocatalytic water purification technology has attracted widespread attention because it can use clean energy solar light as a direct energy source, and is non-toxic and does not produce drug resistance. However, the low photocatalytic efficiency of existing materials is still a key factor restricting the application of photocatalytic technology in practice.

[0003] In the field of photocatalytic water purification, non-metallic polymer photocatalytic material g-C3N4 has attracted widespread attention due to its easy synthesis, environmental friendliness, and good thermal stability and chemical stability. However, the low crystallinity g-C3N4 prepared by traditional direct calcination has a large number of defects and residual hydrogen bonds, which makes it difficult for photo-generated carriers to migrate and separate, resulting in low photocatalytic efficiency. At present, it has been reported that high crystallinity polytriazimide graphite carbon nitride has been prepared by a molten salt assisted method. The relevant experimental results show that it has a greater improvement in carrier separation and migration compared with amorphous graphite carbon nitride. However, the single-phase polytriazimide material has weak light absorption ability, with an absorption cutoff edge of 400 nanometers or less, and almost no visible light response, which seriously restricts its large-scale industrial application. Therefore, it is particularly important to develop high-efficiency visible-light-responsive polytriazimide-based photocatalytic materials.

[0004] A large number of literature shows that the construction of heterojunction can realize the expansion of light absorption range, the increase of separation and transfer efficiency of photo-generated electron-hole pairs, and thus improve the overall photocatalytic efficiency of the composite material. Zinc ferrite is a narrow-bandgap photocatalytic material with visible light response, and its band gap is only 2eV, with a visible light absorption cutoff edge of about 600nm. In addition, zinc ferrite has a suitable energy band position. These unique advantages make it a promising candidate for improving the visible light activity of polytriazimide-based photocatalytic materials. However, so far, there is no related literature report on the construction of polytriazimide / zinc ferrite photocatalytic composite material. SUMMARY

[0005] The application aims to provide a preparation method and application of a polytriazimide / zinc ferrite photocatalytic composite material.

[0006] To achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0007] The application provides a preparation method of a polytriazimide / zinc ferrite photocatalytic composite material, which comprises the following steps:

[0008] (1) preparing a graphite phase carbon nitride (g-C3N4) nanomaterial

[0009] Urea, melamine, thiourea or dicyandiamide are used as raw materials, 5-10 grams of the raw materials are weighed and placed in a corundum crucible, the crucible is transferred into a muffle furnace at 500-600 DEG C after being covered, and is kept for 2-4 hours, and then is ground to obtain the g-C3N4 nanomaterial.

[0010] (2) preparing a high-crystallinity polytriazimide hexagonal prism nanomaterial

[0011] A certain amount of prepared g-C3N4 and a certain amount of potassium chloride and lithium chloride low-temperature molten salt are weighed and ground for a certain time to obtain a uniform mixture; then the mixture is transferred into a corundum crucible, is calcined in a tube furnace under an inert gas atmosphere after being covered, and is cooled, washed, dried and ground to obtain polytriazimide powder.

[0012] (3) preparing a polytriazimide / zinc ferrite photocatalytic composite material

[0013] Firstly, zinc chloride, iron chloride and sodium hydroxide are weighed according to a certain molar ratio and are added into 80 milliliters of anhydrous ethanol, the solid is completely dissolved, and then the polytriazimide hexagonal prism nanomaterial prepared in step (2) is added; after being fully stirred, the mixed solution is transferred into a stainless steel autoclave lined with polytetrafluoroethylene and is heated, finally the sample is washed several times by centrifugation with deionized water and ethanol, is dried in an oven, and is ground to obtain the polytriazimide / zinc ferrite photocatalytic composite material.

[0014] Further, the mass of the g-C3N4 in step (2) is 200-800 milligrams, and the mass of the potassium chloride and lithium chloride low-temperature molten salt is 1-6 grams respectively; the grinding time is 3-15 minutes.

[0015] Further, the reaction conditions for calcining in the tubular furnace in step (2) are as follows: under inert atmosphere, the temperature is raised to 500-600 DEG C at a rate of 5-45 DEG C / min and kept for 12-24 h; the inert atmosphere in the tubular furnace is nitrogen or argon, and the gas flow is 50-200 ml / min.

[0016] Further, the washing agent in step (2) is deionized water boiling water washing, the separation of the material and water is centrifugation, the centrifugal speed is 7000-9000 rpm, and the washing times are 3-5 times.

[0017] Further, the molar ratio of zinc chloride, ferric chloride and sodium hydroxide in step (3) is 1:(1-4):(5-9), and the molar ratio of the amount of polytriazine imide nano material added to zinc chloride is (1-5):1.

[0018] The polytriazine imide / zinc ferrite photocatalytic composite material can be directly applied to photocatalytic purification of organic antibiotic pollutants and pathogenic microorganisms in water under visible light irradiation.

[0019] Invention mechanism:

[0020] The most fundamental starting point of the application is that the main bottleneck restricting the application of semiconductor photocatalytic materials in practice is the easy recombination of photo-generated carriers, which leads to low photocatalytic efficiency. In order to solve this problem, we choose high crystallinity polytriazine imide hexagonal prism photocatalytic material with special crystal face exposure structure as the research object, and construct heterojunction by modifying the surface of the material with visible light responsive narrow band gap semiconductor zinc ferrite nanoparticles, so as to realize the visible light response ability of photocatalytic material and promote the effective separation of photo-generated electrons and holes, and thus fundamentally improve the photocatalytic water purification ability of the photocatalytic material system. The ultimate goal is to design the material so that the organic-inorganic composite semiconductor photocatalytic material system has higher photocatalytic activity and potential commercial value. It can effectively solve the defect of low visible light utilization rate of polytriazine imide and accelerate the separation of photo-generated carriers of single component material, so as to improve the overall photocatalytic activity of the composite material.

[0021] The advantages and beneficial effects of the application are as follows:

[0022] (1) The application first uses narrow band gap zinc ferrite nanoparticles to modify high crystallinity polytriazine imide hexagonal prism photocatalytic material, realizes the simultaneous enhancement of visible light absorption and the solution of the problem of carrier recombination in the bulk phase and surface of photocatalytic material, and provides a train of thought for the design and synthesis of high-efficiency photocatalytic water purification materials in the future.

[0023] (2) The method of the present invention is simple and universal; the obtained polytriazineimide / zinc ferrite photocatalytic composite material has the dual advantages of active crystal face exposure and organic-inorganic hybrid heterojunction, and thus has high photocatalytic activity.

[0024] (3) The polytriazineimide / zinc ferrite photocatalytic composite material prepared by the present invention can be directly used to remove organic pollutants or pathogenic microorganisms in water, and has potential practical application value. Attached Figure Description

[0025] Figure 1 Scanning electron microscope (SEM) images of zinc ferrite, polytriazinimide, and polytriazinimide / zinc ferrite photocatalytic composite materials prepared in Examples 1, 2, and 3.

[0026] Figure 2 Scanning electron microscope (SEM) images and X-ray diffraction (XRD) images of the zinc ferrite, polytriazinimide, and polytriazinimide / zinc ferrite photocatalytic composite materials prepared in Examples 1, 2, and 3.

[0027] Figure 3 The images show a comparison of the light absorption of polytriazineimide and polytriazineimide / zinc ferrite photocatalytic composite materials prepared in Examples 2 and 3.

[0028] Figure 4 The image shows a comparison of the photocatalytic killing effects of zinc ferrite, polytriazinimide, and polytriazinimide / zinc ferrite composite materials prepared in Examples 1, 2, and 3.

[0029] Figure 5 The image shows a comparison of the photocatalytic degradation effects of tetracycline by zinc ferrite, polytriazineimide, and polytriazineimide / zinc ferrite composite materials prepared in Examples 1, 2, and 3. Detailed Implementation

[0030] The technical solution of the present invention will be described more comprehensively and in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the following embodiments are preferred embodiments and are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0031] Example 1

[0032] (1) Weigh 0.136 g of zinc chloride and 0.32 g of ferric chloride, put them into a beaker containing 80 ml of anhydrous ethanol, and stir continuously until the solids are completely dissolved;

[0033] (2) Weigh 0.32 g of sodium hydroxide and add it to the beaker in step (1), then stir magnetically at 700 rpm for 1 hour;

[0034] (3) The liquid mixture obtained in step (2) was transferred into a 100-ml hydrothermal reactor and placed in an oven for solvothermal reaction at 180°C for two hours;

[0035] (4) The material cooled to room temperature was washed with deionized water and anhydrous ethanol, respectively, for 2 times, and dried in a 80°C drying oven for 12 hours to obtain the zinc ferrite nanomaterial (which can be known from the xrd results shown in Figure 2

[0036] Example 2

[0037] (1) 10 grams of urea was weighed into an alumina crucible with a cover, and heated from room temperature to 520°C at a rate of 5°C / min in a muffle furnace and kept for 3 hours, and then programmed cooled to room temperature.

[0038] (2) The light yellow solid material obtained in step (1) was transferred into an agate mortar and ground for 3 minutes to obtain light yellow oligomeric graphite carbon nitride powder;

[0039] (3) 200 milligrams of light yellow powder prepared in step (2) was weighed, and 3.72 grams of potassium chloride and 3.24 grams of lithium chloride were weighed respectively, and they were carefully ground in an agate mortar for 10 minutes to obtain a uniform light yellow mixture;

[0040] (4) The light yellow solid mixture obtained in step (3) was placed in a corundum square boat with a cover, and then placed in a muffle furnace under a nitrogen atmosphere, with a gas flow of 100 ml / min, and heated from room temperature to 550°C at a rate of 30°C / min and kept for 12 hours, and then cooled; The material cooled to room temperature was washed in 98°C hot deionized water, centrifuged (8500 rpm) for a total of three times, and dried in a vacuum drying oven at 60°C for 12 hours to obtain polytriazine imide powder (which can be known from the scanning and Figure 1 xrd results shown in Figure 2

[0041] Example 3

[0042] (1) 0.136 grams of zinc chloride, 0.32 grams of iron chloride and 0.32 grams of sodium hydroxide were weighed into a beaker containing 80 milliliters of anhydrous ethanol, and the stirring was continued until the solids were completely dissolved;

[0043] (2) 100 milligrams of polytriazine imide powder in Example 2 was weighed and added to the beaker of step (1), and ultrasonic was performed for 30 minutes;

[0044] ​​(3) The liquid mixture obtained in step (2) was transferred to a 100-mL hydrothermal reactor, and placed in an oven for solvothermal reaction at 180°C for two hours; the material cooled to room temperature was washed with deionized water and anhydrous ethanol, respectively, and centrifuged (8500 rpm) three times, and dried in a 80°C drying oven for 12 hours to obtain a polytriazine imide / zinc ferrite composite photocatalytic material.

[0045] Example 4

[0046] This example is the application of the zinc ferrite, polytriazine imide and polytriazine imide / zinc ferrite composite materials prepared in Example 1, Example 2 and Example 3 to degrade antibiotic organic pollutants, the process is as follows:

[0047] (1) 20 mg of the product powder obtained in Example 1, 2 and 3 was added to 200 mL of a 50 ppm tetracycline aqueous solution, respectively, and stirred under dark conditions for 30 minutes. Then the suspension was irradiated with a 300W xenon lamp light source, the wavelength of which was visible light of 400-700 nm, and the intensity was 45 mW / cm 2 for 120 minutes.

[0048] (2) Every certain time (0th minute, 5th minute, 10th minute, 20th minute, 40th minute, 60th minute), 10 mL of the suspension was centrifuged to separate the nanopowder, and the supernatant was used to determine the residual tetracycline concentration in the solution. (The formula for calculating the residual rate is residual rate equal to residual concentration divided by initial concentration)

[0049] Example 5

[0050] This example is the application of the zinc ferrite, polytriazine imide and polytriazine imide / zinc ferrite composite materials prepared in Example 1, Example 2 and Example 3 to remove pathogenic microorganisms in water, the process is as follows:

[0051] (1) 10 mg of the product powder obtained in Example 1, 2 and 3 was added to 10 mL of an aqueous solution of Escherichia coli with a concentration of 3*10 7 CFU / mL, respectively, and stirred under dark conditions for 30 minutes. Then the suspension was irradiated with a 300W xenon lamp light source, the wavelength of which was visible light of 400-700 nm, and the intensity was 45 mW / cm 2 for 120 minutes.

[0052] (2) every certain time (15th minute, 30th minute, 45th minute, 60th minute, 90th minute), a certain amount of sample after dilution (to 10 times of the original volume) is coated on solid agar medium, and then placed in a constant temperature incubator for 24 hours, the temperature of the constant temperature incubator is kept at 37°C, and after the incubation is completed, the plate counting method is used for counting. (The calculation formula of the survival rate is equal to the residual bacterial concentration divided by the initial bacterial concentration)

[0053] The experimental results of the above examples and application examples are as follows:

[0054] Figure 1 The scanning electron microscope images of zinc ferrite, polytriazine imide and polytriazine imide / zinc ferrite composite material prepared in Example 1, Example 2 and Example 3 are shown. As can be seen from the figures, the zinc ferrite is a nanoparticle (particle size 20-80 nanometers); the polytriazine imide nanomaterial is a hexagonal prism (diameter (or length of the side of the hexagon perpendicular to the edge) about 50 nanometers (distributed in 40 to 80 nanometers), and the height (or length of the edge) is about 150 nanometers (distributed in 100 to 250 nanometers)) with uniform morphology and smooth surface. For the polytriazine imide / zinc ferrite photocatalytic composite material, it can be seen that there are many very small particles (particle size 20-80 nanometers) distributed on the hexagonal prism of polytriazine imide, which can be confirmed from the morphology that the zinc ferrite nanoparticles are successfully loaded on the polytriazine imide.

[0055] Figure 2 The X-ray diffraction patterns of zinc ferrite, polytriazine imide and polytriazine imide / zinc ferrite composite material prepared in Example 1, Example 2 and Example 3 are shown. As can be seen from the figures: 1) the diffraction peak of zinc ferrite nanoparticles is relatively wide, which is attributed to the ultrafine grain size; 2) the crystal face diffraction peak of polytriazine imide is sharp, indicating its high crystallinity and large grain size. 3) the diffraction peaks of both zinc ferrite and polytriazine imide in the polytriazine imide / zinc ferrite sample further prove that the polytriazine imide / zinc ferrite composite material is successfully prepared.

[0056] Figure 3 The light absorption contrast graph of polytriazine imide and polytriazine imide / zinc ferrite photocatalytic composite material prepared in Example 2 and Example 3 is shown. The absorption cutoff edge of polytriazine imide photocatalytic material is at 390 nanometers, while the light absorption cutoff edge of the composite material reaches 650 nanometers, and its visible light absorption ability far exceeds that of polytriazine imide.

[0057] Figure 4The figure shows the comparison of photocatalytic killing Escherichia coli effect of zinc ferrite, polytriazine imide and polytriazine imide / zinc ferrite composite prepared in Example 1, Example 2 and Example 3. As can be seen from the figure, under the condition of visible light irradiation, the synthesized polytriazine imide / zinc ferrite photocatalytic composite exhibits high photocatalytic bactericidal activity, and more than 99.9999% of the bacteria are completely killed within 2 hours.

[0058] Figure 5 The figure shows the comparison of photocatalytic degradation tetracycline effect of zinc ferrite, polytriazine imide and polytriazine imide / zinc ferrite composite prepared in Example 1, Example 2 and Example 3. As can be seen from the figure, ① under the condition of visible light irradiation, the synthesized single-phase zinc ferrite exhibits weak tetracycline degradation activity, and the polytriazine imide photocatalytic material has almost no visible light activity; ② compared with single-phase photocatalytic material, the construction of heterojunction can significantly improve the photocatalytic activity of the material, and 50 mg / L of tetracycline can be completely degraded by the polytriazine imide / zinc ferrite composite within 60 minutes. Figure 4

[0059] Example 6

[0060] This example is to prepare polytriazine imide / zinc ferrite composites with different contents, and the process and conditions are the same as those in Example 3, except that the mass of polytriazine imide added in step (2) is adjusted. There are two groups of experiments: the first group adds 50 mg of polytriazine imide powder; the second group adds 200 mg of polytriazine imide powder. And respectively according to the operation process and conditions of Example 4, photocatalytic degradation of tetracycline, after 60 minutes of light irradiation, the first group of tetracycline residual rate is 44%, the second group of tetracycline residual rate is 68%, the experiment shows that adding too much or too little polytriazine imide powder will reduce the photocatalytic activity of polytriazine imide / zinc ferrite composite material.

[0061] Example 7

[0062] This example is to prepare different zinc ferrite composites, and the process and conditions are the same as those in Example 3, except that the polytriazine imide added in step (2) is adjusted to use the same mass of g-C3N4 instead of polytriazine imide; and respectively according to the operation process and conditions of Example 4, photocatalytic degradation of tetracycline, after 60 minutes of light irradiation, the tetracycline residual rate is 52%; the experiment shows that compared with the polytriazine imide / zinc ferrite composite photocatalytic material, the photocatalytic activity of the g-C3N4 / zinc ferrite composite material is significantly reduced.

[0063] ​The embodiment results show that the application uses high crystallinity polytriazimide hexagonal prism with special crystal surface exposure structure characteristics as a structure reference; zinc ferrite nanoparticles are grown in situ on the surface, and controllable preparation of polytriazimide / zinc ferrite composite photocatalytic material is successfully realized. By constructing an organic-inorganic hybrid heterojunction, the composite material realizes absorption under visible light and accelerates the separation efficiency of photo-generated carriers. The photocatalytic material excited by visible light can be directly applied to purify organic antibiotic pollutants (tetracycline) and pathogenic microorganisms (escherichia coli) in water, solving the problem of low photocatalytic efficiency of traditional photocatalytic materials.

Claims

1. Use of a polytriazine imide / zinc ferrite photocatalytic composite material, characterized in that, The photocatalytic composite material is directly applied to photocatalytic purification of organic antibiotic pollutants and / or pathogenic microorganisms in water under visible light irradiation, The preparation method of the polytriazine imide / zinc ferrite photocatalytic composite material is as follows: Zinc chloride, iron chloride and sodium hydroxide, and polytriazine imide are added into anhydrous ethanol; after stirring, the mixed solution is heated and reacted in a sealed autoclave, the reaction temperature is 160-190℃, and the reaction time is 1-4 hours; after washing and drying, the polytriazine imide / zinc ferrite photocatalytic composite material is obtained; The molar ratio of zinc chloride, iron chloride and sodium hydroxide is 1:(1-4):(5-9); 0.136 grams of zinc chloride adopts polytriazine imide 80-150 milligrams; 0.136 grams of zinc chloride adopts anhydrous ethanol 60-120 milliliters.

2. Use according to claim 1, characterized in that: The reaction temperature of the heating reaction is 170-180℃, and the reaction time is 2-4 hours.

3. Use according to claim 1, characterized in that: The molar ratio of zinc chloride, iron chloride and sodium hydroxide is 1:(1.8-3):(7-9).

4. Use according to claim 1, characterized in that: The molar ratio of zinc chloride, iron chloride and sodium hydroxide is 1:(1.9-2.5):(7.5-8.5).

5. The use according to claim 1, characterized in that: 0.136 grams of zinc chloride adopts polytriazine imide 90-120 milligrams.

6. The application of claim 1, wherein: The preparation method of the polytriazine imide / zinc ferrite photocatalytic composite material is as follows: first, zinc chloride, iron chloride and sodium hydroxide are added into anhydrous ethanol, and then polytriazine imide is added after the solid is completely dissolved; after stirring, the mixed solution is transferred into a stainless steel autoclave lined with polytetrafluoroethylene and heated; finally, the sample is washed with water and ethanol by centrifugation for 1-6 times in sequence, and then dried in an oven and ground to obtain the polytriazine imide / zinc ferrite photocatalytic composite material; the drying temperature is 60-90℃.

7. The application of claim 1, wherein: 0.136 grams of zinc chloride adopts anhydrous ethanol 70-90 milliliters.

8. The application of claim 1, wherein: 0.136 grams of zinc chloride adopts anhydrous ethanol 75-85 milliliters.

9. The application of claim 1, wherein, The preparation process of polytriazine imide is as follows: g-C3N4, potassium chloride and lithium chloride low-temperature molten salt are ground to obtain a uniform mixture; then the mixture is transferred to a corundum crucible, covered and calcined in a tube furnace under an inert gas atmosphere; after cooling to room temperature, the mixture is washed, dried and ground to obtain polytriazine imide powder; The mass of g-C3N4 is 200-800 milligrams, and the mass of potassium chloride and lithium chloride low-temperature molten salt is 1-6 grams respectively; the grinding time is 3-15 minutes.

10. Use according to claim 9, characterized in that, The calcination reaction conditions in the tube furnace are as follows: under an inert gas atmosphere, the temperature is raised from room temperature to 500-600℃ at a rate of 5-45℃ / min and held for 12-24h; the inert gas in the tube furnace is argon, and the gas flow rate is 50-200 milliliters / minute.

11. Use according to claim 9, characterized in that, The washing is 90-100℃ deionized water washing, and the washing times are 3-5 times.

12. The application of claim 9, wherein, The preparation process of g-C3N4 is as follows: With any one or two or more of urea, melamine, thiourea or dicyandiamide as raw material, 5-10 grams of the above raw material is placed in a corundum crucible, covered and then transferred to a muffle furnace for calcination at 500-600°C, and kept for 2-4 hours. After calcination, grinding is performed to obtain g-C3N4 nanomaterials.

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