Preparation method, product and application of photocatalyst

Abstract

The invention relates to the field of photocatalyst preparation, in particular to a preparation method, a product and application of a photocatalyst. The preparation method of the photocatalyst comprises the following steps: uniformly mixing a ferric salt solution and a perylenetetracarboxylic dianhydride solution, and then adding an H2O2 solution to obtain a mixed solution; and carrying out a hydrothermal reaction on the mixed solution, centrifuging, and washing and drying the obtained precipitate to obtain the photocatalyst. The photocatalyst FeOOH (at) PTCDA is prepared by adopting a hydrothermal method, a heterojunction formed between FeOOH and PTCDA remarkably blocks compounding of photo-generated electrons and photo-generated holes, the photocatalytic electron transfer capacity is improved, a large number of hydroxyl free radicals and superoxide anion free radicals are generated, and the photocatalytic activity of the photocatalyst is improved. Therefore, the strong degradation and reduction capability on oxytetracycline and heavy metal ions in sewage is brought.

Description

Technical Field

[0001] The present invention relates to the field of photocatalyst preparation, and particularly to a preparation method, product and application of a photocatalyst. Background Art

[0002] In recent years, the widespread use of antibiotics has posed a serious threat to human health and the ecological environment. Antibiotics in water bodies affect water quality and may pose potential risks to human health through the food chain. Therefore, it is particularly urgent to find effective water treatment technologies. Among various water treatment technologies, semiconductor photocatalysis is considered to be a highly potential advanced oxidation process (AOPs) due to its advantages of high efficiency, environmental protection and sustainability. This technology can generate hydroxyl radicals with strong oxidation ability by irradiating the catalyst with light, and can effectively degrade difficult-to-treat organic pollutants. However, the current photocatalysis technology still faces some major challenges, such as low migration efficiency of photocatalysts and insufficient redox performance, resulting in a fast recombination rate of photo-generated carriers and thus reducing the reaction activity. Therefore, it is urgent to develop new photocatalysts. Summary of the Invention

[0003] Based on the above, the present invention provides a preparation method, product and application of a photocatalyst (FeOOH@PTCDA).

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] One of the technical solutions of the present invention is a preparation method of a photocatalyst, including the following steps:

[0006] Mix an iron salt solution and a perylene tetracarboxylic dianhydride solution evenly and then add an H2O2 solution to obtain a mixed solution;

[0007] Perform a hydrothermal reaction on the mixed solution, then centrifuge, wash and dry the obtained precipitate to obtain the photocatalyst.

[0008] Another technical solution of the present invention is a photocatalyst prepared according to the above preparation method.

[0009] Another technical solution of the present invention is the application of the above photocatalyst in photocatalytic degradation of antibiotics.

[0010] The present invention discloses the following technical effects:

[0011] The present invention uses a hydrothermal method to prepare the photocatalyst FeOOH@PTCDA. The heterojunction formed between FeOOH and PTCDA significantly blocks the recombination of photo-generated electrons and photo-generated holes, improves the ability of photocatalytic electron transfer, and generates a large number of hydroxyl radicals and superoxide anion radicals, thereby bringing its strong degradation ability for organic matter (oxytetracycline) in sewage.

[0012] The FeOOH@PTCDA of the present invention is applied to a photocatalytic system, which can efficiently generate oxygen-containing free radicals, thereby rapidly removing antibiotics in water. In addition, the photogenerated electrons generated in the system can also treat other heavy metal ions (hexavalent chromium ions) that are difficult to reduce in sewage. Description of the Drawings

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0014] Figure 1 XRD patterns of the photocatalysts prepared in Example 3 and Comparative Examples 4 and 5.

[0015] Figure 2 Scanning electron microscope images of the photocatalysts prepared in Example 3 and Comparative Examples 4 and 5; among them, (a) is the photocatalyst prepared in Comparative Example 4, (b) is the photocatalyst prepared in Comparative Example 5, and (c) and (d) are the scanning electron microscope images of the photocatalyst prepared in Example 3 at different magnification factors.

[0016] Figure 3 Results of photocatalytic degradation of oxytetracycline by the photocatalysts prepared in Example 3 and Comparative Examples 1, 2, 3, 4, and 5.

[0017] Figure 4 Results of photocatalytic reduction of hexavalent chromium ions by the photocatalysts prepared in Example 3 and Comparative Examples 1, 2, 3, 4, and 5.

[0018] Figure 5 Photocatalytic experiment cycle diagram of the photocatalyst prepared in Example 3. Detailed Embodiments

[0019] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0020] It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention. In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0021] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although only preferred methods and materials are described in this invention, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0022] Without departing from the scope or spirit of this invention, various improvements and changes can be made to the specific embodiments of the specification of this invention, which are obvious to those skilled in the art. Other embodiments obtained from the specification of this invention are obvious to those skilled in the art. The specification and examples of this invention are merely exemplary.

[0023] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0024] The "%" mentioned in this invention represents mass percentage unless otherwise specified.

[0025] A first aspect of this invention provides a method for preparing a photocatalyst, comprising the following steps:

[0026] Mix an iron salt solution and a perylene tetracarboxylic dianhydride solution evenly and then add an H2O2 solution to obtain a mixed solution;

[0027] Perform a hydrothermal reaction on the mixed solution, then centrifuge, wash and dry the obtained precipitate to obtain the photocatalyst.

[0028] In a preferred embodiment of this invention, the mass ratio of the iron salt in the iron salt solution to the perylene tetracarboxylic dianhydride in the perylene tetracarboxylic dianhydride solution is (2.08 - 2.12):(4.87 - 4.95); the iron salt is FeSO4·7H2O.

[0029] In this invention, too much or too little addition amount of the iron salt will lead to a significant reduction in the degradation efficiency of the prepared photocatalyst for oxytetracycline. Only when the mass ratio of the iron salt to the perylene tetracarboxylic dianhydride is within the above ratio range, the degradation efficiency of the prepared photocatalyst for oxytetracycline is the best.

[0030] This invention does not make a special limitation on the concentration of the iron salt solution. The amount of solvent water used in the iron salt solution only needs to enable the iron salt to be fully dissolved.

[0031] This invention does not make a special limitation on the concentration of the perylene tetracarboxylic dianhydride solution. The amount of solvent water used in the perylene tetracarboxylic dianhydride solution only needs to enable the perylene tetracarboxylic dianhydride to be fully dissolved.

[0032] In a preferred embodiment of the present invention, the mass concentration of the H2O2 solution is 30%; the mass-volume ratio of the iron salt in the iron salt solution to the H2O2 solution is (2.08 - 2.12) g: 18 ml.

[0033] In a preferred embodiment of the present invention, the temperature of the hydrothermal reaction is 150 degrees Celsius and the time is 24 hours.

[0034] In the present invention, if the temperature of the hydrothermal reaction is too high, it will cause thermal decomposition of the catalyst; if the temperature is too low, it will result in too low a yield of the catalyst; if the time of the hydrothermal reaction is too long, it will cause a change in the structure of the catalyst; if the time is too short, it will lead to a decrease in the activity of the catalyst. Only when the temperature and time of the hydrothermal reaction are the above parameters, the photocatalyst prepared has the highest degradation efficiency for oxytetracycline.

[0035] In a preferred embodiment of the present invention, the drying is specifically vacuum drying at 80 degrees Celsius for 12 hours.

[0036] The second aspect of the present invention provides a photocatalyst prepared by the above preparation method.

[0037] The third aspect of the present invention provides the application of the above photocatalyst in photocatalytic degradation of antibiotics.

[0038] In a preferred embodiment of the present invention, the antibiotic is oxytetracycline.

[0039] In a preferred embodiment of the present invention, the photocatalyst as claimed in claim 6 is added to the wastewater containing antibiotics, and the antibiotics are degraded by visible light irradiation for 20 min.

[0040] In a preferred embodiment of the present invention, the addition amount of the photocatalyst in the wastewater containing antibiotics is 0.5 mg / mL.

[0041] In the actual application process, after the degradation of antibiotics is completed, the residual photocatalyst in the reaction system can be recovered through a filter membrane.

[0042] The present invention also experimented with using the prepared photocatalyst to degrade tetracycline. The results showed that the highest degradation efficiency for tetracycline was 51%, which was not as good as the degradation efficiency for oxytetracycline.

[0043] The technical solutions of the present invention, unless otherwise specified, are all conventional solutions in the art. The reagents or raw materials used, unless otherwise specified, are all purchased from commercial channels or have been made public.

[0044] The following is a detailed description of the technical solutions provided by the present invention in conjunction with the examples, but they should not be construed as limiting the scope of protection of the present invention.

[0045] Example 1

[0046] Dissolve 2.12 g of FeSO4·7H2O in 30 ml of deionized water to form solution A. Dissolve 4.90 g of PTCDA (perylene tetracarboxylic dianhydride) in 35 ml of water to obtain solution B. Under stirring, mix solution A and B and gradually add 18 ml of H2O2 (30%) dropwise. After no bubbles are generated, obtain solution C. Transfer solution C into a hydrothermal reactor, place it in an oven, and set the temperature and time to 150 °C for 24 hours. After the reaction is completed, take out the mixture and centrifuge to obtain precipitate E. Wash precipitate E several times with deionized water and ethanol. After removing impurities, dry it in vacuum at 80 °C for 12 hours to obtain the photocatalyst (FeOOH@PTCDA).

[0047] Example 2

[0048] Dissolve 2.10 g of FeSO4·7H2O in 30 ml of deionized water to form solution A. Dissolve 4.87 g of PTCDA (perylene tetracarboxylic dianhydride) in 35 ml of water to obtain solution B. Under stirring, mix solution A and B and gradually add 18 ml of H2O2 (30%) dropwise. After no bubbles are generated, obtain solution C. Transfer solution C into a hydrothermal reactor, place it in an oven, and set the temperature and time to 150 °C for 24 hours. After the reaction is completed, take out the mixture and centrifuge to obtain precipitate E. Wash precipitate E several times with deionized water and ethanol. After removing impurities, dry it in vacuum at 80 °C for 12 hours to obtain the photocatalyst (FeOOH@PTCDA).

[0049] Example 3

[0050] Dissolve 2.08 g of FeSO4·7H2O in 30 ml of deionized water to form solution A. Dissolve 4.88 g of PTCDA (perylene tetracarboxylic dianhydride) in 35 ml of water to obtain solution B. Under stirring, mix solution A and B and gradually add 18 ml of H2O2 (30%) dropwise. After no bubbles are generated, obtain solution C. Transfer solution C into a hydrothermal reactor, place it in an oven, and set the temperature and time to 150 °C for 24 hours. After the reaction is completed, take out the mixture and centrifuge to obtain precipitate E. Wash precipitate E several times with deionized water and ethanol. After removing impurities, dry it in vacuum at 80 °C for 12 hours to obtain the photocatalyst (FeOOH@PTCDA).

[0051] Example 4

[0052] Dissolve 2.11 g of FeSO4·7H2O in 30 ml of deionized water to form solution A. Dissolve 4.95 g of PTCDA (perylene tetracarboxylic dianhydride) in 35 ml of water to obtain solution B. Under stirring, mix solution A and B and dropwise add 18 ml of H2O2 (30%) until no bubbles are generated to obtain solution C. Transfer solution C into a hydrothermal reaction kettle, place it in an oven, and set the temperature and time to 150 °C for 24 hours. After the reaction is completed, take out the mixture and centrifuge to obtain precipitate E. Wash precipitate E several times with deionized water and ethanol, and after removing impurities, dry it in vacuum at 80 °C for 12 hours to obtain the photocatalyst (FeOOH@PTCDA).

[0053] Comparative Example 1

[0054] Dissolve 0.7 g of FeSO4·7H2O in 30 ml of deionized water to form solution A. Dissolve 6.3 g of PTCDA (perylene tetracarboxylic dianhydride) in 35 ml of water to obtain solution B. Under stirring, mix solution A and B and dropwise add 18 ml of H2O2 (30%) until no bubbles are generated to obtain solution C. Transfer solution C into a hydrothermal reaction kettle, place it in an oven, and set the temperature and time to 150 °C for 24 hours. After the reaction is completed, take out the mixture and centrifuge to obtain precipitate E. Wash precipitate E several times with deionized water and ethanol, and after removing impurities, dry it in vacuum at 80 °C for 12 hours to obtain the photocatalyst (FP-1).

[0055] Comparative Example 2

[0056] Dissolve 3.5 g of FeSO4·7H2O in 30 ml of deionized water to form solution A. Dissolve 3.5 g of PTCDA (perylene tetracarboxylic dianhydride) in 35 ml of water to obtain solution B. Under stirring, mix solution A and B and dropwise add 18 ml of H2O2 (30%) until no bubbles are generated to obtain solution C. Transfer solution C into a hydrothermal reaction kettle, place it in an oven, and set the temperature and time to 150 °C for 24 hours. After the reaction is completed, take out the mixture and centrifuge to obtain precipitate E. Wash precipitate E several times with deionized water and ethanol, and after removing impurities, dry it in vacuum at 80 °C for 12 hours to obtain the photocatalyst (FP-5).

[0057] Comparative Example 3

[0058] Dissolve 4.9 g of FeSO4·7H2O in 30 ml of deionized water to form solution A. Dissolve 2.1 g of PTCDA (perylene tetracarboxylic dianhydride) in 35 ml of water to obtain solution B. Under stirring, mix solution A and B and add 18 ml of H2O2 (30%) dropwise. After no bubbles are generated, obtain solution C. Transfer solution C into a hydrothermal reactor, place it in an oven, and set the temperature and time to 150 °C for 24 hours. After the reaction is completed, take out the mixture and centrifuge to obtain precipitate E. Wash precipitate E several times with deionized water and ethanol, and after removing impurities, dry it in vacuo at 80 °C for 12 hours to obtain the photocatalyst (FP-7).

[0059] Comparative Example 4

[0060] Dissolve 6.96 g of FeSO4·7H2O in 75 ml of deionized water to form solution F. Under stirring, add 18 ml of H2O2 (30%) dropwise to solution F. After no bubbles are generated, obtain solution G. Transfer solution G into a hydrothermal reactor, place it in an oven, and set the temperature and time to 150 °C for 24 hours. After the reaction is completed, take out the mixture and centrifuge to obtain precipitate H. Wash precipitate H several times with deionized water and ethanol, and after removing impurities, dry it in vacuo at 80 °C for 12 hours to obtain the photocatalyst (FeOOH).

[0061] Comparative Example 5

[0062] Dissolve 6.96 g of PTCDA (perylene tetracarboxylic dianhydride) in 75 ml of deionized water to form solution I. Under stirring, add 18 ml of H2O2 (30%) dropwise to solution I. After no bubbles are generated, obtain solution J. Transfer solution J into a hydrothermal reactor, place it in an oven, and set the temperature and time to 150 °C for 24 hours. After the reaction is completed, take out the mixture and centrifuge to obtain precipitate K. Wash precipitate K several times with deionized water and ethanol, and after removing impurities, dry it in vacuo at 80 °C for 12 hours to obtain the photocatalyst (PCA).

[0063] Apply the photocatalysts prepared in Examples 1-4 and Comparative Examples 1-5 to the photocatalytic degradation of oxytetracycline. The specific steps are as follows: Take 30 mg of the photocatalyst and add it to 100 mL of an oxytetracycline aqueous solution with a concentration of 15 mg / L. Use a 500 W xenon lamp as the light source (380 - 750 nm) to carry out the photocatalytic degradation reaction. The dark reaction is 30 minutes. After illumination, use a 3 mL pipette to aspirate 3 mL of the suspension every 20 minutes, and repeat 4 times. Then analyze the oxytetracycline content in the suspension on a UV-visible absorption spectrometer, calculate and record the degradation rate.

[0064] Table 1 Degradation rate of oxytetracycline by the catalysts prepared in Examples and Comparative Examples under 120 min of illumination

[0065]

[0066]

[0067] The photocatalysts prepared in Examples 1-4 and Comparative Examples 1-5 were applied to the photocatalytic reduction of hexavalent chromium ions. The specific steps were as follows: 30 mg of the photocatalyst and 30 mg of citric acid were added to 100 mL of potassium dichromate at 15 mg / L, and a 500 W xenon lamp was used as the light source (380 - 750 nm) for photocatalytic degradation reaction. The dark reaction was carried out for 30 minutes. After illumination, 3 mL of the suspension was aspirated every 20 minutes using a 3 mL pipette and repeated 4 times. Then, the content of hexavalent chromium ions in the suspension was analyzed on a UV-visible absorption spectrometer, and the reduction rate was calculated and recorded.

[0068] Table 2 Reduction rates of the catalysts prepared in Examples and Comparative Examples for hexavalent chromium ions at 120 min of illumination

[0069] Reduction rate % Example 1 91.69％ Example 2 92.07％ Example 3 93.51％ Example 4 90.63％ Comparative Example 1 79.25％ Comparative Example 2 87.87％ Comparative Example 3 85.87％ Comparative Example 4 54.25％ Comparative Example 5 49.55％

[0070] Figure 1 The X-ray diffraction (XRD) patterns of the photocatalysts prepared in Example 3, Comparative Example 4, and Comparative Example 5 were shown. Analysis was carried out using a Malvern Panalytical Empyrean device under operating conditions of 40 kV voltage and 40 mA current, with Cu Kα radiation. The XRD pattern of FeOOH showed 8 spectral bands at 2θ = 63.9 nm, 61.4 nm, 59.2 nm, 53.1 nm, 41.2 nm, 36.6 nm, 33.2 nm, and 21.2 nm, corresponding to the (061), (002), (151), (221), (140), (111), (130), and (110) crystal planes respectively. While the XRD pattern of PTCDA showed one spectral band at 2θ = 27.5 nm, corresponding to the (102) lattice plane. The main spectral bands of FeOOH@PTCDA were in good agreement with those of FeOOH and PTCDA, further confirming the successful synthesis of the photocatalyst.

[0071] Figure 2 The scanning electron microscope (SEM) images of Example 3 and Comparative Examples 4 and 5 were shown. Analysis was carried out using a Hitachi SU8010 field emission scanning electron microscope in Japan. Figure 2 In (A), (B), (C), and (D) are images of Comparative Example 4 (FeOOH monomer), Comparative Example 5 (PCA), and two different magnification images of Example 3 respectively.

[0072] From Figure 2 As can be seen from (A) in, the FeOOH monomer of Comparative Example 4 showed obvious granular fine-grain characteristics, with a rough surface and significant interactions between particles. Figure 2In (B), it shows that the PCA of Comparative Example 5 has an obvious rod-like structure and a relatively smooth surface, indicating that the reaction in Comparative Example 5 did not change the structure of the PTCDA monomer.

[0073] Figure 2 In (C) and Figure 2 In (D), the FeOOH@PTCDA composite photocatalysts at different magnifications are shown respectively. It is clearly observed that the powdery FeOOH monomer wraps the rod-like PTCDA monomer, and the surface roughness increases significantly. This increase in roughness helps to increase the surface area of the photocatalyst, thereby improving the reaction rate of the photocatalyst. This result further verifies the successful preparation of the photocatalyst.

[0074] Figure 3 The photocatalysts of Example 3 and Comparative Examples 1, 2, 3, 4, and 5 in the degradation of oxytetracycline are shown. The results show that the photocatalyst prepared in Example 3 has the fastest degradation efficiency compared with the photocatalysts prepared under different ratios of FeSO4·7H2O and PTCDA (Comparative Examples 1, 2, 3, 4, and 5), and the degradation rate reaches 64.09% within 120 minutes. Compared with the monomer FeOOH (Comparative Example 4), the rate is increased by 29.7%.

[0075] Figure 4 The photocatalysts of Example 3 and Comparative Examples 1, 2, 3, 4, and 5 in the reduction of hexavalent chromium ions are shown. The results show that the photocatalyst prepared in Example 3 has the fastest reduction efficiency compared with the photocatalysts prepared under different ratios of FeSO4·7H2O and PTCDA (Comparative Examples 1, 2, 3, 4, and 5), and the reduction rate reaches 94.5% within 120 minutes. Compared with the monomer FeOOH (Comparative Example 4), the rate is increased by 72%.

[0076] To verify the stability of the prepared FeOOH@PTCDA composite photocatalyst, the photocatalyst prepared in Example 3 was subjected to a photocatalytic cycle test. The experimental results are as Figure 5 shown. The degradation rate of oxytetracycline decreased slightly after five cycles, and the degradation rate in the fifth cycle decreased by 1.9%. This may be attributed to the loss of the catalyst during the sampling process and the accumulation of oxytetracycline pollutants in the residues of each cycle. This indicates that the FeOOH@PTCDA photocatalyst has good stability.

[0077] The above-described embodiments are only described in a preferred manner of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. A preparation method of a photocatalyst, characterized in that, It includes the following steps: Mix the iron salt solution and the perylene tetracarboxylic dianhydride solution evenly, and then add the H2O2 solution to obtain a mixed solution; Perform a hydrothermal reaction on the mixed solution, then centrifuge, wash and dry the obtained precipitate to obtain the photocatalyst.

2. The preparation method of the photocatalyst according to claim 1, characterized in that, The mass ratio of the iron salt in the iron salt solution to the perylene tetracarboxylic dianhydride in the perylene tetracarboxylic dianhydride solution is (2.08 - 2.12):(4.87 - 4.95); the iron salt is FeSO4·7H2O.

3. The preparation method of the photocatalyst according to claim 1, characterized in that, The mass concentration of the H2O2 solution is 30%; the mass-to-volume ratio of the iron salt in the iron salt solution to the H2O2 solution is (2.08 - 2.12) g:18 ml.

4. The preparation method of the photocatalyst according to claim 1, characterized in that, The temperature of the hydrothermal reaction is 150 °C and the time is 24 hours.

5. The preparation method of the photocatalyst according to claim 1, wherein The drying is specifically vacuum drying at 80 °C for 12 hours.

6. A photocatalyst prepared by the preparation method according to any one of claims 1 to 5.

7. Use of the photocatalyst according to claim 6 in photocatalytic degradation of antibiotics.

8. The application according to claim 7, wherein The antibiotic is oxytetracycline.

9. The application according to claim 7, wherein Add the photocatalyst according to claim 6 to the wastewater containing antibiotics, and irradiate with visible light for 20 min to achieve the degradation of antibiotics.

10. The application according to claim 9, wherein The addition amount of the photocatalyst in the wastewater containing antibiotics is 0.5 mg / mL.

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