Method for producing hydrogen peroxide by using organic wastewater based on PDI / PMSO composite photocatalytic system

Abstract

The invention belongs to the cross technical field of environmental catalysis and green chemical industry, and particularly relates to a PDI / PMSO-based composite photocatalytic system and a method for producing hydrogen peroxide by using organic wastewater. According to the invention, a PDI / PMSO composite photocatalytic system is obtained by coupling a PDI supramolecular photocatalyst with methyl phenyl sulfoxide (PMSO) wastewater according to a specific concentration ratio. According to the PDI / PMSO composite photocatalytic system, the yield of H2O2 can be remarkably increased, and when the concentration of PMSO is 10 mM, the yield of H2O2 reaches 137.28 [mu] M.g <-1 >. H <-1 > and is increased by 4.3 times compared with a pure water system. The system promotes photo-induced electron-hole pair separation (steady-state fluorescence intensity is reduced by 37%) through a synergistic effect, enhances electron conduction efficiency (photocurrent is improved by 1.8 times), and keeps excellent cycle stability (the yield is kept above 80% after 10 cycles) and practical water body applicability. The method is simple in process and low in cost, and an integrated solution is provided for recycling of organic wastewater and green synthesis and application of H2O2.

Description

Technical Field

[0001] The invention belongs to the cross-technical field of environmental catalysis and green chemical industry, and specifically relates to a method for producing hydrogen peroxide based on a PDI / PMSO composite photocatalytic system and utilizing organic wastewater. Background Art

[0002] As a new generation of green oxidant, hydrogen peroxide (H2O2) exhibits excellent redox properties due to its unique molecular structure-activity relationship, and has both environmental compatibility (decomposition products are H2O and O2) and industrial universality. This feature makes it have irreplaceable application value in advanced oxidation processes (AOPs), fine organic synthesis and biomedical engineering. However, more than 90% of the global H2O2 production capacity still relies on the traditional anthraquinone cycle method. This process not only involves multi-stage hydrogenation / oxidation steps, but also has significant energy consumption and three waste pollution problems, which is in fundamental contradiction with the carbon neutrality strategy orientation. Therefore, the development of efficient and low-energy H2O2 green synthesis technology has become one of the core challenges for achieving sustainable chemical manufacturing.

[0003] Photocatalytic synthesis technology provides an innovative breakthrough to solve the above difficulties. Its essence is to use the photogenerated carriers (e) of semiconductor photosensitive materials to generate - -h + The two-electron oxygen reduction reaction is considered to be the key pathway for efficient H2O2 synthesis due to its superior thermodynamic driving force and selectivity. However, due to the rapid recombination effect of photogenerated carriers (quantum efficiency is generally <10%), the H2O2 yield of existing photocatalytic systems is still difficult to meet industrial needs.

[0004] Regarding the bottleneck problem of low carrier separation efficiency, strategies such as noble metal cocatalysis, energy band structure regulation, and sacrificial agent assistance have been proposed in the academic community. However, the high cost of noble metals and the large-scale consumption of sacrificial agents severely restrict their practical applications. The latest research shows that introducing a reversible redox mediator (such as the quinone / phenol system) can significantly increase the carrier lifetime through a dynamic electron transfer mechanism. These breakthroughs reveal the key role of electron mediators in optimizing the reaction path and provide a new paradigm for the development of self-sustaining catalytic systems. It is worth noting that sulfoxide pollutants (such as phenyl methyl sulfoxide - PMSO) widely present in industrial wastewater may possess dual functions of pollutant resource utilization and electron transfer promotion due to their unique electronic structure characteristics (the S=O group contains highly active lone pair electrons). Theoretical studies have shown that the S=O group can act as an electron acceptor to capture photo-generated electrons and reduce the activation energy barrier of O2 activation through intramolecular charge transfer. Constructing a photocatalytic / PMSO system to deepen the understanding of the photocatalytic electron transfer mechanism provides theoretical support for the development of "treating waste with waste" environmental catalytic technologies. The main technical problems existing in the prior art are as follows: 1. Low photocatalytic yield of H2O2: The H2O2 yield of traditional PDI-based catalysts in pure water systems is lower than ~25 μM·g -1 ·h -1 , making it difficult to meet industrial demands; 2. High carrier recombination rate: The narrow bandgap characteristic of PDI leads to rapid recombination of photo-generated electron-hole pairs, reducing the quantum efficiency; 3. Insufficient stability: The yield of most modified PDI catalysts decays by more than 30% after 5 cycles of use (Zhang et al., Appl. Catal. B 2021, 298, 120558).

[0005] Existing studies mostly improve performance through noble metal loading (such as Pt modification) or heterostructure construction (such as g-C3N4 / PDI), but there are problems such as high cost and complex processes. The applicant has found through research that after coupling PMSO wastewater with PDI, the above defects can be significantly improved through the interfacial electron transfer effect.

[0006] Therefore, in this application, a composite photocatalytic system is formed by compounding perylene diimide (PDI) and phenyl methyl sulfoxide (PMSO), which can be used for in-situ production of hydrogen peroxide in organic wastewater. Summary of the Invention

[0007] Aiming at the deficiencies of the existing technology, the present invention provides a PDI / PMSO composite photocatalytic system by compounding PDI and phenyl methyl sulfoxide (PMSO), which can improve the H2O2 yield under light conditions and can also efficiently degrade different pollutants (bisphenol A, fluoroquinolone, and dyes) under light conditions.

[0008] To achieve the above technical objectives, the present invention adopts the following technical solutions: A PDI / PMSO composite photocatalytic system, comprising a PDI supramolecular photocatalyst and PMSO, wherein the mass ratio of the PDI supramolecular photocatalyst to PMSO is (0.03~7.5):1, preferably (0.036 - 7.143):1, and more preferably 0.143:1.

[0009] Specifically, in the PDI / PMSO composite photocatalytic system, the concentration of PDI is 0.1~0.5 g / L (preferably 0.2 g / L), and the concentration of PMSO is 0.5~20 mM (preferably 10 mM).

[0010] Furthermore, the present invention also provides a preparation method of the PDI / PMSO composite photocatalytic system. Specifically, the PDI supramolecular photocatalyst and PMSO are sequentially dispersed in water to construct the PDI / PMSO composite photocatalytic system.

[0011] Furthermore, the preparation method of the PDI supramolecular photocatalyst includes the following steps: 1) Under a protective atmosphere, perylene-3,4,9,10-tetracarboxylic dianhydride, β-alanine and imidazole are mixed and placed in a reaction vessel, and then reacted at a certain temperature for a certain time under the protective atmosphere. After the reaction, it is cooled to room temperature (25±5°C) and ground into powder; 2) The product of step 1) is washed with absolute ethanol and HCl solution for 6~18 h in sequence, and then filtered by suction until the pH of the filtrate is neutral; 3) The product of step 2) is dried and then dispersed in water. Triethylamine and HCl solution are added, and after shaking for 1~3 h, it is filtered by suction and dried to finally obtain a powdery PDI supramolecular photocatalyst.

[0012] Specifically, in step 1), the protective atmosphere is an atmosphere formed by nitrogen, argon, etc.

[0013] Specifically, in step 1), the mass ratio of perylene-3,4,9,10-tetracarboxylic dianhydride to β-alanine is 1:(1~2).

[0014] Specifically, in step 1), the mass ratio of β-alanine to imidazole is 1:(4~6).

[0015] Specifically, in step 1), the reaction temperature is 100~120°C, and the reaction time is 2~6 h.

[0016] Specifically, in step 3), the dosage (mass) ratio of the product to triethylamine and HCl solution is (1~2.68):(0.6~1):(2~4).

[0017] Furthermore, the present invention also provides an application of the PDI / PMSO composite photocatalytic system in photocatalytic hydrogen peroxide production.

[0018] Furthermore, based on a general inventive concept, the present invention also provides a method for photocatalytic hydrogen peroxide production using the PDI / PMSO composite photocatalytic system, comprising the following steps: First, prepare a powdered PDI supramolecular photocatalyst, then disperse the powdered PDI supramolecular photocatalyst in water, and then add PMSO to construct a PDI / PMSO composite photocatalytic system; irradiate with a light source for 5 to 60 minutes for a photocatalytic reaction, and measure the concentration of H2O2.

[0019] Specifically, in the PDI / PMSO composite photocatalytic system, the concentration of PDI is 0.1 to 0.5 g / L (preferably 0.2 g / L), and the concentration of PMSO is 0.5 to 20 mM (preferably 10 mM).

[0020] Specifically, the light source is a xenon lamp or a mercury lamp, with a wavelength greater than 400 nm and an illuminance of 100 ± 3 mW·cm -2 .

[0021] Alternatively, the light source is sunlight, with a wavelength greater than 295 nm and an illuminance of 95 mW·cm -2 .

[0022] Preferably, during the photocatalytic reaction, the light source used can also be a blue LED lamp (wavelength 455 - 460 nm, illuminance 6.2 mW cm -2 ), a violet LED lamp (wavelength 390 - 400 nm, illuminance 4.0 mW cm -2 ), a green LED lamp (wavelength 515 - 530 nm, illuminance 6.0 mW cm -2 ), a yellow LED lamp (wavelength 590 - 595 nm, illuminance 4.0 mW cm -2 ), a red LED lamp (wavelength 655 - 660 nm, illuminance 11.0 mW cm -2 ).

[0023] Specifically, during illumination, the power is (100 - 300) W, preferably 300 W.

[0024] Preferably, before irradiation, the PDI / PMSO composite photocatalytic system is first subjected to a dark reaction (10 - 60) minutes under dark conditions.

[0025] Furthermore, the PDI / PMSO composite photocatalytic system can be reused when photocatalytically producing hydrogen peroxide, and the number of reuse times is 1 - 10 times, specifically, it can be 1 time, 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times or 10 times.

[0026] Specifically, the water is domestic tap water, rainwater, domestic sewage, industrial sewage, agricultural sewage, river water, lake water or seawater, etc.

[0027] Furthermore, the present invention also provides an application of the PDI / PMSO composite photocatalytic system in photocatalytic degradation of organic pollutants.

[0028] Specifically, the PDI / PMSO composite photocatalytic system of the present invention can efficiently degrade various water pollutants under the condition that multiple water pollutants (bisphenol A pollutants, fluoroquinolone pollutants and / or dye pollutants) coexist.

[0029] Furthermore, based on a general inventive concept, the present invention also provides a method for photocatalytic degradation of water pollutants using the PDI / PMSO composite photocatalytic system, including the following steps: First, prepare a powdered PDI supramolecular photocatalyst, then disperse the powdered PDI supramolecular photocatalyst in water containing water pollutants, and then add PMSO to construct a PDI / PMSO composite photocatalytic system; irradiate with a light source for 5 - 60 min for photocatalytic reaction.

[0030] Specifically, in the PDI / PMSO composite photocatalytic system, the concentration of PDI is 0.1 - 0.5 g / L (preferably 0.2 g / L), and the concentration of PMSO is 0.5 - 20 mM (preferably 10 mM).

[0031] Preferably, before irradiation, the PDI / PMSO composite photocatalytic system is first subjected to a dark reaction for (10 - 60) min under dark conditions.

[0032] Specifically, the light source is a xenon lamp or a mercury lamp, with a wavelength greater than 400 nm and an illuminance of 100 ± 3 mW·cm -2 .

[0033] Or, the light source is sunlight, with a wavelength greater than 295 nm and an illuminance of 95 mW·cm -2 .

[0034] Preferably, during the photocatalytic reaction, the light source used can also be a blue LED lamp (wavelength 455 - 460 nm, illuminance 6.2 mW cm -2 )、a violet LED lamp (wavelength 390 - 400 nm, illuminance 4.0 mW cm-2 ), green LED lights (wavelength: 515 - 530 nm, illuminance: 6.0 mW cm -2 ), yellow LED lights (wavelength: 590 - 595 nm, illuminance: 4.0 mW cm -2 ), red LED lights (wavelength: 655 - 660 nm, illuminance: 11.0 mW cm -2 ).

[0035] Specifically, during illumination, the power is (100 - 300) W, preferably 300 W.

[0036] Specifically, the water pollutants are bisphenol A pollutants, fluoroquinolone pollutants, and / or dye pollutants.

[0037] Preferably, it is one or more of BPA (bisphenol A), BPAF (bisphenol AF), BPB (bromophenol blue), BPF (bisphenol F), CIP (ciprofloxacin), ENX (enoxacin), NOR (norfloxacin), OFX (ofloxacin), RMB (rhodamine B), MLB (methylene blue), NGB (naphthol green B), MTO (methyl orange).

[0038] Specifically, the concentration of the water pollutants is 1 - 5 mg / L, preferably 2 mg / L.

[0039] Specifically, the water is tap water for domestic use, rainwater, domestic sewage, industrial sewage, agricultural sewage, river water, lake water, seawater, etc.

[0040] The present invention has significant innovation and for the first time reveals the non - linear enhancement effect of the PMSO concentration gradient (0.5 - 20 mM) on the photocatalytic H2O2 production performance of PDI. Compared with traditional modification technologies, the present invention breaks through the limitation of relying on complex chemical modifications. By simply mixing PDI with PMSO wastewater, a substantial increase in the production rate is achieved, successfully realizing the technological breakthrough of "wastewater photocatalytic resource utilization".

[0041] Through a simple preparation process, the present invention adds PDI to PMSO wastewater, which can achieve a 4.3 - fold increase in the production rate and break through the complexity of traditional processes. The wastewater treatment method of the present invention can be applied to scenarios such as the treatment of wastewater after H2O2 synthesis and the treatment of various types of wastewater.

[0042] Compared with the prior art, the advantages of the present invention are as follows: 1. Production rate breakthrough: Compared with the traditional pure PDI catalyst, the H2O2 production rate of the PDI / PMSO composite photocatalytic system of the present invention has increased by 4.3 times (as Figure 1As shown). This significant increase in productivity indicates that the composite system has great potential for application in photocatalytic resource-based synthesis of H2O2.

[0043] 2. Carrier regulation: 1) Enhancement of photocurrent intensity. Photocurrent intensity is an important indicator to measure the separation and transport efficiency of photo-generated carriers. The experimental results show that when the concentration of PMSO is 10 mM, the photocurrent intensity is increased by 1.8 times compared with pure PDI (as Figure 2 shown). This indicates that the addition of PMSO effectively promotes the transport of photo-generated electrons and reduces the recombination of carriers; 2) Reduction of steady-state fluorescence intensity. The steady-state fluorescence spectrum can reflect the recombination of photo-generated carriers. Pure PDI has a strong fluorescence peak at 674 nm, while when 10 mM PMSO is added, the fluorescence intensity is reduced by 37% (as Figure 3 shown). This further proves that the composite system can effectively inhibit the recombination of photo-generated electron-hole pairs and improve the quantum efficiency.

[0044] 3. Cycling stability: To evaluate the stability of the composite photocatalytic system, a cycling stability test was carried out. The results show that after 10 cycles of use, the H2O2 productivity of the system can still maintain more than 80% of the initial value (as Figure 4 shown). This excellent cycling stability indicates that the PDI / PMSO composite photocatalytic system has good durability and can meet the long-term operation requirements of actual industrial production.

[0045] 4. Structural stability: The materials before and after the reaction were analyzed by means of TEM (as Figure 5 a-d shown), DRS (as Figure 5 e shown), and FT-IR (as Figure 5 f shown), etc. The results show that the crystal structure, optical properties, and functional groups of PDI have not changed significantly before and after the reaction. This indicates that the composite photocatalytic system has good structural stability during the photocatalytic reaction process, providing a strong guarantee for its long-term stable operation.

[0046] 5. Application reliability: Evaluate the activity of the PDI / PMSO composite photocatalytic system under different light sources (such as Figure 6 ), different co-existing pollutants (such as Figure 7 ), and different water bodies (such as Figure 8 ); the results show that the PDI / PMSO composite photocatalytic system has good adaptability and high H2O2 productivity and activity for multiple types of scenarios. Description of the Drawings

[0047] Figure 1 It is a comparison chart of the productivity of H2O2 produced by the PDI / PMSO composite photocatalytic system described in Example 2 under different PMSO concentrations; Figure 2 Photocurrent response curves of PDI and different composite photocatalytic systems; Figure 3 Steady-state fluorescence spectra in systems of PDI and different PMSO concentrations; Figure 4 Cyclic stability test of H2O2 production by the PDI / PMSO composite photocatalytic system described in Example 2 at a certain concentration of PMSO; Figure 5 For material characterization comparison, where, Figure 5 a - d are TEM images, Figure 5 a and 5c are before turning on the light, Figure 5 b is after reacting for 60 minutes, Figure 5 d is PDI; Figure 5 e is a DRS image, Figure 5 f is an FT-IR image; Figure 6 H2O2 production test of the PDI / PMSO composite photocatalytic system described in Example 2 under different light sources; Figure 7 Photocatalytic degradation test of the PDI / PMSO composite photocatalytic system described in Example 2 under the condition of coexistence of different pollutants; Figure 8 H2O2 production test of the PDI / PMSO composite photocatalytic system described in Example 2 under different water body conditions. Detailed implementation manners

[0048] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0049] Unless otherwise specified, the instrument equipment used in the following embodiments are all commercially available conventional instrument equipment; unless otherwise specified, the reagents, raw materials, etc. used in the following embodiments are all conventional commercially available products and can be obtained through commercial channels.

[0050] Example 1 A preparation method of a PDI supramolecular photocatalyst, the specific steps are as follows: 1) Under an argon atmosphere, 6 mmol of perylene-3,4,9,10-tetracarboxylic dianhydride (2.353 g), 40 mmol of β-alanine (3.563 g) and 18.0 g of imidazole are mixed and placed in a reaction vessel, and then under an argon atmosphere at 5 °C·min -1The temperature was raised to 100 °C at a certain rate and reacted for 4 h. After the reaction, it was cooled to room temperature (25 ± 5 °C) and ground into powder. 2) The product of step 1) was stirred and washed successively with 100 mL of absolute ethanol and 300 mL of 2.0 M HCl solution for 12 h, and then filtered until the pH of the filtrate was neutral. 3) The product of step 2) was dried at 60 °C and then dispersed in 200 mL of ultrapure water. 0.83 mL of triethylamine and 27.30 mL of 4.0 M HCl solution were added. After shaking for 3 h, it was filtered and dried to finally obtain a powdered PDI supramolecular photocatalyst.

[0051] Example 2 Construction of PDI / PMSO composite photocatalytic system: 0.01 g of powdered PDI supramolecular photocatalyst was dispersed in 50 mL of ultrapure water. Then, PMSO was added respectively to a final concentration of 0, 0.5, 1, 5, 10, 20 mM to construct a PDI / PMSO composite photocatalytic system.

[0052] Application Test 1 Test on photocatalytic production of H2O2 using the PDI / PMSO composite photocatalytic system described in Example 2. The specific steps are as follows: 1. The PDI / PMSO composite system of Example 2 (where the final concentration of PMSO is 0, 0.5, 1, 5, 10, 20 mM respectively) was first placed in a dark environment for adsorption for 30 min, and then reacted under simulated sunlight (PLS-SXE300 / 300UV light source (xenon lamp), light intensity 100 ± 3 mW·cm -2 , wavelength greater than 400 nm, light power is 300 W) for 60 min; 2. Samples were taken regularly (once every 10 min, the sampling volume was 1 mL), and the concentration of H2O2 was measured by the iodometric method (measurement method reference: Environmental Science & Technology, 1988, 22(7): 798 - 806).

[0053] The test results are as Figure 1 shown. It can be seen from Figure 1 that for the optimal group (the final concentration of PMSO is 10 mM), the H2O2 production rate reaches 137.28 μM·g -1 ·h -1 . Compared with the traditional pure PDI catalyst, the H2O2 production rate of the PDI / PMSO composite photocatalytic system has increased by 4.3 times (as Figure 1 shown). This significant increase in the production rate indicates that this composite system has great application potential in the photocatalytic resource synthesis of H2O2.

[0054] Performance Test of PDI / PMSO Composite Photocatalytic System 1. Photocurrent response test: The photocurrent response curve measurement experiment was carried out using a CHI-760E electrochemical workstation (CH Instruments, USA).

[0055] The test results are as Figure 2 shown. The test groups are: pure PDI, PDI + 1 mM PMSO, and PDI + 10 mM PMSO respectively.

[0056] The photocurrent intensity is an important indicator to measure the separation and transport efficiency of photo-generated carriers. Figure 2 The results show that when the concentration of PMSO is 10 mM, the photocurrent intensity is increased by 1.8 times compared with pure PDI (as Figure 2 shown). This indicates that the addition of PMSO effectively promotes the transport of photo-generated electrons and reduces the recombination of carriers.

[0057] 2. Steady-state fluorescence spectrum: It was detected using a Hitachi F7000 fluorescence spectrometer (Japan). Different concentrations of PMSO were configured in the PDI mixture, stirred and mixed evenly, and 1 mL was taken and placed in the fluorescence detector for analysis. The excitation wavelength was 390 nm.

[0058] The test results are as Figure 3 shown. The test groups are: pure PDI, 1 mM PMSO, 5 mM PMSO, and 10 mM PMSO respectively; it can be seen from Figure 3 this that the position of the characteristic peak: there is a strong fluorescence peak at 674 nm in the pure PDI group, and the fluorescence intensity in the 10 mM PMSO group is reduced by 37%.

[0059] The steady-state fluorescence spectrum can reflect the recombination of photo-generated carriers. Figure 3 The results show that pure PDI has a strong fluorescence peak at 674 nm, while when 10 mM PMSO is added, the fluorescence intensity decreases from the peak intensity of 418 a.u. at 674 nm to 263 a.u., and the fluorescence intensity is reduced by 37% (as Figure 3 shown). This further proves that this composite system can effectively inhibit the recombination of photo-generated electron-hole pairs and improve the quantum efficiency.

[0060] 3. Material characterization comparison and catalyst characterization method: Under the condition of an accelerating voltage of 200 kV, the morphology, surface characteristics, and aggregation of the photocatalyst were analyzed by transmission electron microscopy (TEM, JEM-2100F, JEOL Ltd., Japan). The spectral characteristics of the prepared photocatalyst were tested in the wavelength range of 200 - 800 nm using a UV-vis diffuse reflectance spectrometer (UV-vis / DRS, UV-3600 plus, SHIMADZU, Japan). The covalent bonds and special groups in the photocatalyst were determined using a Nicolet 6700 Fourier transform infrared spectrometer (FTIR, Thermo Fisher Scientific, USA).

[0061] The concentration of PDI in the system was 0.2 g / L, and the concentration of PMSO was 10 mM.

[0062] Through TEM (as shown in Figure 5 a - d; TEM images of PDI before turning on the light (a) and (c), and after 60 minutes of reaction (b) and (d)), DRS (as shown in Figure 5 e), and FT-IR (as shown in Figure 5 f) and other characterization methods were used to analyze the materials before and after the reaction. Figure 5 The results showed that in the TEM images: there was no significant change in the morphology of PDI before and after the reaction; in the DRS images: the position of the absorption edge remained the same; in the FT-IR images: there was no obvious shift in the characteristic functional groups. The results showed that the crystal structure, optical properties, and functional groups of PDI did not change significantly before and after the application test 1. This indicates that the composite photocatalytic system has good structural stability during the photocatalytic reaction process, providing a strong guarantee for its long-term stable operation.

[0063] Application test 2: Cycling stability test The cycling stability of the PDI / PMSO composite photocatalytic system described in Test Example 2 was tested. The specific steps were as follows: The stability of the catalyst was evaluated by recovering the PDI catalyst and repeatedly placing it in PMSO (10 mM) wastewater (referring to Application Test 1, adding PMSO to ultrapure water to simulate wastewater) for multiple rounds of photocatalytic synthesis of H2O2 experiments. The concentration of PDI was 0.2 g / L, and the light source was a xenon lamp (light intensity 100 ± 3 mW·cm -2 , wavelength greater than 400 nm, and light power of 300 W).

[0064] The results of the cycling stability test are as shown in Figure 4 (PMSO concentration was 10 mM). Figure 4 In it, the horizontal axis: the number of cycles (1 - 10 times), and the vertical axis: on the left is the H2O2 production rate (μM·g -1 ·h-1 ); The right side is the retention rate of H2O2 production rate (%).

[0065] As can be seen from Figure 4 , the morphology and spectral characteristics of the catalyst remain unchanged before and after the reaction. After 10 cycles of use, the H2O2 production rate of this system can still maintain more than 80% of the initial value (as Figure 4 shown). This excellent cycle stability indicates that the PDI / PMSO composite photocatalytic system has good durability and can meet the long-term operation requirements of actual industrial production.

[0066] Application Test 3: Testing with Different Light Sources Under different light source conditions, an experiment on photocatalytic production of H2O2 using the PDI / PMSO composite photocatalytic system described in Example 2 was carried out. The test method was the same as that of Application Test 1, except that after the dark reaction, light with different wavelengths was used as the reaction light source for photocatalytic reaction, and the usage power of each lamp was the same as that of Application Test 1.

[0067] The test results are as Figure 6 shown, Figure 6 in (PMSO concentration is 10 mM), the lower horizontal axis: PDI light source absorption and corresponding sunlight spectrum; the upper horizontal axis: different light sources, the left vertical axis: absorbance; the right vertical axis: H2O2 production rate.

[0068] As can be seen from Figure 6 , under different light source conditions (direct sunlight, wavelength greater than 295 nm, illuminance is 95 mW / cm 2 ; blue LED lamp, wavelength is 455 - 460 nm, illuminance is 6.2 mW / cm -2 ; purple LED lamp, wavelength is 390 - 400 nm, illuminance is 4.0 mW / cm -2 ; green LED lamp, wavelength is 515 - 530 nm, illuminance is 6.0 mW / cm -2 ; yellow LED lamp, wavelength is 590 - 595 nm, illuminance is 4.0 mW / cm -2 ; red LED lamp, wavelength is 655 - 660 nm, illuminance is 11.0 mW / cm -2 ), the PDI / PMSO composite photocatalytic system described in Example 2 has good H2O2 production rate. Among them, there is an obvious phenomenon of H2O2 production rate improvement under different light source conditions in actual sunlight and simulated sunlight. Even under long-wavelength red light, there is an obvious production rate, which is 0.76 times higher than that of the single xenon lamp system (Vis-PDI). This again indicates that the addition of PMSO can not only effectively enhance the ability of PDI to photocatalytically synthesize H2O2, but also has great potential in photocatalytic synthesis of H2O2 under renewable sunlight.

[0069] Application Test Four: Degradation Test of Different Coexisting Pollutants An experiment was conducted to photocatalytically degrade various water pollutants using the PDI / PMSO composite photocatalytic system described in Example 2. The test method was the same as that of Application Test One, except that photocatalytic degradation was carried out under the condition of coexistence of different water pollutants, including BPA (bisphenol A), BPAF (bisphenol AF), BPB (bromophenol blue), BPF (bisphenol F), CIP (ciprofloxacin), ENX (enoxacin), NOR (norfloxacin), OFX (ofloxacin), RMB (rhodamine B), MLB (methylene blue), NGB (naphthol green B), and MTO (methyl orange). Specifically, the concentration of each water pollutant was 2 mg / L.

[0070] The experimental conditions were as follows: reaction for 60 min under simulated sunlight (PLS-SXE300 / 300UV light source (xenon lamp, light intensity 100 ± 3 mW·cm -2 , wavelength greater than 400 nm, and light illumination power of 300 W).

[0071] The test results are shown as Figure 7 follows, Figure 7 (with PMSO concentration of 10 mM). Horizontal axis: different pollutants (bisphenol A type, fluoroquinolone type, and dye type); left vertical axis: pollutant degradation rate; inset: degradation situation of PMSO.

[0072] The results showed that in the pre-produced H2O2 + mercury lamp system, the PDI / PMSO composite photocatalytic system described in Example 2 was effective in degrading twelve coexisting (added separately) new pollutants such as bisphenol A type, fluoroquinolone type, and dye type. Compared with the single mercury lamp photocatalytic degradation, the rate constants were significantly improved (23.1% - 352.0%, with an average increase of 98.6%). This indicates that the PDI coupling PMSO system developed in this study has the ability to resourcefully produce H2O2, and the generated H2O2 can be applied to the degradation of new environmental pollutants.

[0073] Application Test Five: Tests in Different Water Bodies An experiment was conducted to photocatalytically produce H2O2 using the PDI / PMSO composite photocatalytic system described in Example 2 under different water body conditions. The test method was the same as that of Application Test One, except that photocatalytic reactions were carried out under different water body conditions, including sea water, lake water, tap water, river water, and ultrapure water.

[0074] The test results are shown as Figure 8 follows, Figure 8Among them, the horizontal axis represents different water bodies; the left vertical axis represents the H2O2 production rate.

[0075] The results show that for the systems containing PMSO pollutants (PMSO concentration is 10 mM) under different water bodies, there is no significant impact on the H2O2 production rate, and all can maintain a relatively high level.

[0076] In summary, the present invention couples a perylene diimide (PDI) supramolecular photocatalyst with methyl phenyl sulfoxide (PMSO) wastewater in a specific concentration ratio to obtain a PDI / PMSO composite photocatalytic system. The system of the present invention promotes the separation of photo-generated electron-hole pairs through synergistic effects (the steady-state fluorescence intensity decreases by 37%), enhances the electron conduction efficiency (the photocurrent increases by 1.8 times), and maintains excellent cyclic stability (the production rate remains above 80% after 10 cycles) and practical water body applicability. The process of the present invention is simple and low-cost, providing an integrated solution for the resource utilization of organic wastewater and the green synthesis and application of H2O2.

[0077] Experiments prove that the PDI / PMSO composite system performs excellently under different light sources, coexistence of different pollutants, and different water body conditions; among them, in terms of degrading pollutants, the degradation rate constant has a significant increase compared with that without pre-treatment for H2O2 production (23.1% - 352.0%, with an average increase of 98.6%). Therefore, it has broad application prospects in sewage treatment, water body reduction, adsorption and degradation, etc.

[0078] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A PDI / PMSO composite photocatalytic system, characterized in that: It includes PDI supramolecular photocatalyst and PMSO, wherein the mass ratio of PDI supramolecular photocatalyst to PMSO is (0.03~7.5):

1.

2. The method for preparing the PDI / PMSO composite photocatalytic system according to claim 1, characterized in that: The specific steps are: dispersing PDI supramolecular photocatalyst and PMSO in water in sequence, thereby constructing a PDI / PMSO composite photocatalytic system; In the PDI / PMSO composite photocatalytic system, the PDI concentration is 0.1-0.5 g / L, and the PMSO concentration is 0.5-20 mM.

3. The PDI / PMSO composite photocatalytic system according to claim 1, characterized in that: The preparation method of PDI supramolecular photocatalyst comprises the following steps: 1) Under a protective atmosphere, perylene-3,4,9,10-tetracarboxylic dianhydride, β-alanine and imidazole are mixed and placed in a reaction container, and then reacted at a certain temperature for a certain time under a protective atmosphere, cooled to room temperature after the reaction, and ground into powder; 2) washing the product of step 1) with anhydrous ethanol and HCl solution for 6 to 18 hours, and then filtering until the pH of the filtrate is neutral; 3) The product of step 2) is dried and dispersed in water, triethylamine and HCl solution are added, and the mixture is shaken for 1 to 3 hours, filtered, and dried to finally obtain a powdered PDI supramolecular photocatalyst.

4. The preparation method according to claim 3, characterized in that: In step 1), the mass ratio of perylene-3,4,9,10-tetracarboxylic dianhydride to β-alanine is 1:(1-2); in step 1), the mass ratio of β-alanine to imidazole is 1:(4-6).

5. The preparation method according to claim 3, characterized in that: The reaction temperature in step 1) is 100-120°C, and the reaction time is 2-6 hours.

6. Use of the PDI / PMSO composite photocatalytic system according to claim 1 in photocatalytic production of hydrogen peroxide.

7. A method for photocatalytically producing hydrogen peroxide using the PDI / PMSO composite photocatalytic system of claim 1, comprising the following steps: Firstly, a powdered PDI supramolecular photocatalyst was prepared, and then the powdered PDI supramolecular photocatalyst was dispersed in water, and then PMSO was added to construct a PDI / PMSO composite photocatalytic system; a light source was used to irradiate for 5 to 60 minutes to carry out a photocatalytic reaction, and samples were taken at regular intervals to measure the H2O2 concentration; In the PDI / PMSO composite photocatalytic system, the PDI concentration is 0.1-0.5 g / L, and the PMSO concentration is 0.5-20 mM.

8. Use of the PDI / PMSO composite photocatalytic system according to claim 1 in photocatalytic degradation of organic pollutants.

9. A method for photocatalytically degrading water pollutants using the PDI / PMSO composite photocatalytic system of claim 1, comprising the following steps: Firstly, a powdered PDI supramolecular photocatalyst is prepared, and then the powdered PDI supramolecular photocatalyst is dispersed in water containing water pollutants, and then PMSO is added to construct a PDI / PMSO composite photocatalytic system; The photocatalytic reaction was carried out by irradiating the light source for 5 to 60 min; In the PDI / PMSO composite photocatalytic system, the PDI concentration is 0.1-0.5 g / L, the PMSO concentration is 0.5-20 mM; the water pollutants are bisphenol A pollutants, fluoroquinolone pollutants and / or dye pollutants; and the concentration of the water pollutants is 1-5 mg / L.

10. The use according to claim 6 or 8, characterized in that: The water is domestic tap water, rainwater, domestic sewage, industrial sewage, agricultural sewage, river water, lake water or sea water.

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