A novel photocatalytic composite material, preparation thereof and application thereof to degradation of polyfluorinated organic pollutants
By preparing mesoporous mSiO2@CeO2 composite materials, the problems of low visible light utilization and high catalyst cost in photocatalytic degradation of polyfluorinated organic pollutants were solved, achieving efficient degradation and environmentally friendly treatment of polyfluorinated organic pollutants.
Patent Information
- Application Number
- CN202310700960.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-13
- Publication Date
- 2025-12-19
- Estimated Expiration
- 2043-06-13
AI Technical Summary
Existing photocatalytic degradation technologies for polyfluorinated organic pollutants suffer from problems such as low utilization of visible light and solar energy, high catalyst costs, poor environmental compatibility, and lack of effective treatment for mineralized degradation products.
Mesoporous mSiO2@CeO2 composite material was prepared by physical grinding and hydrothermal method. Visible light was used to excite CeO2 for catalytic degradation, and the degradation products were fixed by the adsorption of SiO2 to avoid secondary pollution.
It achieves efficient utilization of visible light and solar energy to degrade polyfluorinated organic pollutants, with a high degradation rate. The degradation products are fixed on the catalyst surface, avoiding environmental pollution. It is low-cost and environmentally friendly.
Smart Images
Figure CN117123208B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the field of environmental remediation and new pollutant treatment, and particularly relates to a novel photocatalytic composite material, preparation thereof, and application of the photocatalytic composite material to degradation of multi-fluorine organic pollutants. BACKGROUND
[0002] Since the 21st century, persistent fluorine-containing fine chemicals have been one of the important categories in the four product systems of fluorine chemical industry, mainly including fluorine-containing organic intermediates, fluorine-containing electronic chemicals, fluorine-containing surfactants, fluorine-containing fine chemicals for lithium batteries, and environmentally friendly fluorine-containing extinguishing agents, which are widely used in medicine, pesticide, dye, semiconductor, and modified material. The use of these industrial chemicals has continuously improved the living standards of human beings, but at the same time, it has silently damaged the environment around us and affected our living space. At present, as one of the new pollutants, persistent organic pollutants (POPs) have attracted widespread attention due to their high toxicity, persistence, bioaccumulation, and long-distance transfer in the environment. For example, chlorinated industrial compounds, polycyclic aromatic hydrocarbons (PAHs), pesticides, liquid crystal monomer materials fluorobiphenyl analogues (FBAs), and perfluoroalkyl and polyfluoroalkyl substances (PFAS). Through the large use of such products and industrial wastewater discharge, the soil and water in the ecosystem are polluted. The high stability and bioaccumulation make them possible to be bioconcentrated and biomagnified in the food chain, and finally have toxic effects on wild animals and humans. Therefore, it is urgent to monitor, control, and develop new treatment technologies for such new persistent organic fluorine pollutants.
[0003] Because of the wide distribution of polyfluoroalkyl substances (PFAS) in nature, their strong toxicity poses a serious threat to human health, so the treatment of PFAS (such as PFOA, PFOS, etc.) in the environment is particularly important. Currently, the reported methods for treating PFAS include traditional treatment techniques such as biodegradation and physical adsorption techniques. Biodegradation is low-cost and has a small environmental impact, but bioremediation has specific selectivity for pollutants, a long cycle, and an uncontrollable reaction process. Adsorption methods using ion exchange resins and activated carbon for perfluorinated compounds are widely used in industrial treatment of PFAS such as PFOA, PFOS, etc. Adsorption methods have the advantages of simple equipment, low cost, easy operation, and the ability to treat high-concentration wastewater. However, adsorption methods only transfer pollutants from the liquid phase to the solid catalyst, which is mainly a transfer and enrichment process, and cannot degrade pollutants into non-toxic or less toxic chemicals. In addition, there is a risk of secondary pollution from adsorbents, exchange resins, or membranes, which need to be further treated. New treatment techniques such as electrochemical technology, ultrasonic oxidation technology, and plasma technology can achieve a high removal rate and defluorination rate of perfluorinated compounds. However, the additional input of electrical and thermal energy increases the cost of perfluoroalkyl substance treatment technology, making it difficult to be widely used in industrial wastewater treatment. Chemical oxidation technology involves adding strong oxidizing chemicals such as S2O8 2- to the wastewater system, which rapidly reacts with PFAS to mineralize organic pollutants. However, strong oxidizing agents have poor environmental compatibility and can cause secondary damage to water quality and soil ecosystems.
[0004] Solar photocatalytic processes can utilize green energy to mineralize most organic compounds into green products, so they have attracted the attention of researchers as a potential way to degrade persistent pollutants. Current photocatalytic treatment techniques can achieve a very high degradation rate of perfluorinated compounds, but the selection of light sources is focused on high-energy deep ultraviolet, ultraviolet, or high-pressure mercury lamps, with low utilization of visible light and solar energy. The catalysts are focused on some heavy metals (Ga2O3) and noble metals (BiOHP), which have poor environmental compatibility and high manufacturing costs. There is little research on the subsequent treatment of degradation products F - and CO2. Zhao et al. used mechanical chemical destruction of PFOA with BaTiO3 as a grinding agent, revealing that the degradation of PFOA is an electron-dominated reduction process, and after degradation, F - forms BaF2 with Ba 2+ , making F - not discharged. Wei et al. used ultrasonic pyrolysis to achieve a defluorination rate of 100% for PFOA, but there is little research on the subsequent treatment of free F -, CO2 and the like are not subjected to further research and treatment. In the photocatalytic degradation system, the secondary pollution risk assessment of degradation products is not involved. SUMMARY
[0005] The present application aims to provide a new photocatalytic composite material and its preparation and application in the degradation of polyfluoro organic pollutants, so as to solve the problems of the existing photocatalytic degradation of polyfluoro organic pollutants, such as low utilization rate of visible light and solar energy, high cost of catalyst manufacturing, poor environmental compatibility, and secondary pollution of degradation products such as CO2, F - lack of further post-treatment research and other problems.
[0006] A preparation method of a new photocatalytic composite material, comprising the following steps:
[0007] (1) Under room temperature conditions, tetraethyl orthosilicate, deionized water, ammonia water, and hexadecyl trimethyl ammonium bromide are stirred uniformly to reach a gel state, repeatedly washed with deionized water, dried at 120-180 DEG C for 1-5h, then physically and mechanically ground uniformly, calcined at 400-600 DEG C in a muffle furnace for 4-8h to obtain mesoporous mSiO2;
[0008] (2) After dissolving Ce(NO3)3.6H2O in deionized water, mesoporous mSiO2 prepared in step (1) is added, and water solvent is removed by a rotary evaporator under reduced pressure, the mixed product is dried for 10-20h, then physically and mechanically ground uniformly, and calcined at 250-300 DEG C in a muffle furnace for 1-4h to obtain mSiO2@CeO2.
[0009] In the present application, tetraethyl orthosilicate is used as a silicon source, and silica gel is formed under the conditions of hexadecyl trimethyl ammonium bromide and alkaline. The silica gel is calcined at high temperature to remove carbon chains and form mesoporous mSiO2. The existing mesoporous mSiO2 particles mainly have a pore size of 2-5nm. In the present application, the agglomeration of the gel is dispersed by sufficient physical grinding, so that the formation of mSiO2 with a large pore size is more favorable during high-temperature calcination. After physical grinding and calcination, mesoporous, mesoporous and macroporous mSiO2 can be observed, and the macropores mainly have a size of 50-60nm. The hydrothermal method of the present application enables in-situ generation of CeO2 on the surface of mSiO2, and the chemical bonding force is stronger. In the present application, the precursor of CeO2 is uniformly dispersed on the surface of mSiO2 by sufficient physical grinding, which is more conducive to the uniform distribution of CeO2 on the surface of mSiO2 during calcination.
[0010] In the present application, Ce(NO3)3.6H2O is dissolved in deionized water, avoiding the introduction of organic solvents.
[0011] Preferably, the molar ratio of tetraethyl orthosilicate, deionized water, ammonia water, and hexadecyl trimethyl ammonium bromide in step (1) is 0.01-1:1.6-3:0.015-0.1:0.002-0.8.
[0012] Preferably, the molar ratio of Ce(NO3)3·6H2O and mSiO2 added in step (2) is 1:20, and the final mSiO2@5% CeO2 composite material can be obtained.
[0013] The new photocatalytic composite material obtained by the preparation method.
[0014] The application of the new photocatalytic composite material, for the degradation of multi-fluorine organic pollutants.
[0015] Preferably, the multi-fluorine organic pollutants include one or more of PFOA, PFOS, F-53B, OFB, DTMDEB, 3,4,5-trifluorobenzenboronic acid, 3,5-difluoroaniline, florfenicol.
[0016] The method for degrading multi-fluorine organic pollutants by the new photocatalytic composite material, comprising the steps of: taking a multi-fluorine organic pollutant aqueous solution as a pollutant water sample, adding the new photocatalytic composite material to the water sample; and degrading under visible light.
[0017] Preferably, the concentration of the new photocatalytic composite material is 2.5g / L.
[0018] Preferably, the pH of the pollutant water sample is 7.
[0019] Preferably, the visible light can be one or more of a 400nm-760nm LED lamp, a 300W xenon lamp, and outdoor sunlight.
[0020] The semiconductor photocatalyst mSiO2@CeO2 of the application degrades fluorine-containing organic pollutants through adsorption-photocatalysis synergistic effect. CeO2 acts as a photocatalyst and plays a leading catalytic role. Its oxidation potential is high by 2.64eV (VS NHE ) and e- and h+ are generated at both ends of the catalyst under light excitation; SiO2 plays a main adsorption role, the mesoporous mSiO2 synthesized in the application can adsorb more organic pollutants, so that they are closely adsorbed with the catalyst, accelerating the attack speed of active free radicals on organic pollutants in the photocatalysis process. Compared with commercial SiO2, the application has more excellent adsorption capacity and can improve the photocatalytic degradation efficiency of multi-fluorine organic pollutants.
[0021] Compared with a series of catalysts such as monatomic Pt modified TiO2, the catalyst of the application uses low-energy-consumption visible light or even outdoor sunlight, and can also adsorb fluorine ions.
[0022] Compared with existing technologies, this invention uses mesoporous mSiO2 to prepare the composite catalyst mSiO2@CeO2, which exhibits visible light response, a band gap of 2.85 eV, and a large specific surface area of 864.7 m². 2 g -1 The mSiO2@CeO2 of this invention can degrade fluorinated organic pollutants through an adsorption-photocatalytic synergistic effect, achieving efficient degradation of polyfluorinated organic pollutants such as PFOA, PFOS, OFB, and DTMDEB under sunlight, and can adsorb and immobilize the degradation product F. - To avoid F in the solution phase after degradation - Fluorides entering the environment cause secondary pollution and toxicity. The mesoporous mSiO2 of this invention is an environmentally friendly material, with inexpensive and readily available raw materials and the ability to adsorb organic pollutants. The low-loading doping of CeO2 (mSiO2@5%CeO2) provides better environmental compatibility and economic benefits. The preparation method of this invention does not require the introduction of strong oxidants, has simple reaction conditions, and does not require high-energy ultraviolet lamps, electrical energy, mechanical energy input, or high-temperature conditions. Attached Figure Description
[0023] Figure 1 This is a schematic diagram of the preparation of the photocatalytic composite material mSiO2@CeO2.
[0024] Figure 2 The UV-Vis diffuse reflectance spectrum (a) and band gap width (b) of the photocatalytic composite material mSiO2@5%CeO2 are shown.
[0025] Figure 3 The image shows the X-ray powder diffraction (XRD) pattern of the photocatalytic composite material mSiO2@CeO2.
[0026] Figure 4 The image shows a scanning electron microscope (SEM) image of the photocatalytic composite material mSiO2@5%CeO2.
[0027] Figure 5 Transmission electron microscopy (TEM) image of the photocatalytic composite material mSiO2@5%CeO2.
[0028] Figure 6 XPS spectra of the composite material mSiO2@5%CeO2 before and after degradation; (a) is the crystal diffraction pattern of the catalyst mSiO2@5%CeO2 before and after degradation; (b) is the high-resolution XPS spectrum of C1s of the catalyst mSiO2@5%CeO2 before and after degradation; (c) is the high-resolution XPS spectrum of F1s of the catalyst mSiO2@5%CeO2 before and after degradation.
[0029] Figure 7EDS images of the composite material mSiO2@CeO2 before (a) and after (b) degradation.
[0030] Figure 8 (a) is a commercial silica gel powder loaded with 5% cerium oxide, and (b) is mesoporous silica (mSiO2) loaded with 5% cerium oxide, and (c) is a summary chart of the degradation effects of two different silica and cerium oxide composites on different model polyfluoroorganic pollutants.
[0031] Figure 9 The degradation effects of different cerium oxide loadings of the photocatalytic composite material mSiO2@5% CeO2, mSiO2@10% CeO2, mSiO2@20% CeO2, mSiO2@40% CeO2, and mSiO2@70% CeO2 on OFB under 400 nm visible light for 4 h are compared.
[0032] Figure 10 (a) is the pore size distribution of mSiO2 and mSiO2@5% CeO2, and (b) is the N2 adsorption-desorption graph of mSiO2 and mSiO2@5% CeO2.
[0033] Figure 11 The degradation effect of the photocatalytic composite material mSiO2@5% CeO2 on OFB is shown in the graph.
[0034] Figure 12 The degradation effect of the photocatalytic composite material mSiO2@5% CeO2 on DTMEDB is shown in the graph.
[0035] Figure 13 The degradation effect of the photocatalytic composite material mSiO2@5% CeO2 on 3,4,5-trifluorobenzoic acid is shown in the graph.
[0036] Figure 14 The degradation effect of the photocatalytic composite material mSiO2@5% CeO2 on 3,5-difluoroaniline is shown in the graph.
[0037] Figure 15 The degradation effect of the photocatalytic composite material mSiO2@5% CeO2 on florfenicol is shown in the graph.
[0038] Figure 16 The degradation effect of the photocatalytic composite material mSiO2@5% CeO2 on ciprofloxacin is shown in the graph.
[0039] Figure 17 The element content distribution graph of the photocatalytic composite material mSiO2@5% CeO2 before and after degradation. DETAILED DESCRIPTION
[0040] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings.
[0041] Example 1
[0042] A preparation method of a new type of photocatalytic composite material, as shown in the figure, comprises the following steps: Figure 1
[0043] (2) Mesoporous mSiO2 is synthesized by a hydrothermal method. 2.2 mL of tetraethyl orthosilicate (TEOS), 28.8 mL of deionized water and 0.28 mL of ammonia are measured, 0.729 g of cetyltrimethylammonium bromide (CTAB) is weighed; under room temperature conditions, stirring is uniform, reaching a gel state, repeatedly washing with deionized water, drying at 150°C for 3 h, putting the precursor powder into an agate mortar, physically and mechanically grinding uniformly, calcining at 500°C in a muffle furnace for 6 h, and obtaining mesoporous mSiO2.
[0044] (2) mSiO2@CeO2 is synthesized by a hydrothermal method, and the mass ratio of Ce(NO3)3·6H2O to mSiO2 is adjusted to synthesize mSiO2 with different CeO2 loadings, including mSiO2@5% CeO2, mSiO2@10% CeO2, mSiO2@20% CeO2, mSiO2@40% CeO2, and mSiO2@70% CeO2. For example, the molar ratio of Ce(NO3)3·6H2O to mSiO2 is 1:20, and finally mSiO2@5% CeO2 composite material can be obtained. The specific synthesis method is as follows: Ce(NO3)3·6H2O is added to a 100 mL round-bottom flask and dissolved with an appropriate amount of deionized water. Then, the previously synthesized mesoporous mSiO2 particles are added to the mixed solution, and the water solvent is removed by a rotary evaporator under reduced pressure. The mixed product is dried for 12 h, the precursor powder is put into an agate mortar, and is physically and mechanically ground uniformly. Finally, the Ce(NO3)3 / mSiO2 is calcined in a muffle furnace at 270°C for 3 h to obtain mSiO2@CeO2.
[0045] XRD, scanning electron microscopy, and UV-visible diffuse reflectance spectroscopy are used to characterize the crystal phase structure, surface morphology and band gap width of the photocatalyst prepared in Example 1.
[0046] Figure 2 In the UV-Vis diffuse reflectance spectrum shown in (a), mSiO2@5%CeO2 exhibits light absorption in the 400nm-450nm range. Visible light at 400nm can be used to catalyze the generation of electrons and holes in mSiO2@5%CeO2, further converting it into active free radicals. mSiO2@5%CeO2 can absorb visible light in the 400nm-800nm wavelength range, allowing for degradation using visible light sources. Figure 2 As shown in (b), the band gap of the catalyst is 2.86 eV, which indicates that the composite catalyst synthesized in Example 1 has visible light response performance.
[0047] Figure 3 These are XRD diffraction patterns of mSiO2 with different CeO2 loadings. In the diffraction patterns of each composite catalyst, the corresponding CeO2 lattice diffraction peaks are clearly visible; and through... Figure 5 Transmission electron microscopy clearly shows the lattice fringes of the 111 crystal plane of CeO2, indicating that the composite catalyst mSiO2@CeO2 was successfully synthesized.
[0048] pass Figure 4 Scanning electron microscopy (SEM) revealed that the morphology of mSiO2@CeO2 was granular, consisting of densely packed microspheres, and its porous structure was visible under transmission electron microscopy (TEM). The particle size was less than 50 nm. Figure 10 The adsorption-desorption of N2 by the catalyst was tested, and the specific surface area of pure mesoporous mSiO2 was found to be as high as 900.7 m². 2 g -1 The specific surface area of mSiO2@5%CeO2 is 864.7 m². 2 g -1 The pore size distribution is mainly concentrated in the 30-60nm and 2-5nm ranges. Small, medium, and large pores are all visible.
[0049] Figure 9 The figure compares the degradation effects of photocatalytic composite materials with different cerium oxide loadings (mSiO2@5%CeO2, mSiO2@10%CeO2, mSiO2@20%CeO2, mSiO2@40%CeO2, and mSiO2@70%CeO2) on OFB after 4 hours of reaction under 400 nm visible light. The figure shows that SiO2@5%CeO2 has the best degradation effect on OFB.
[0050] Example 2
[0051] 1. A novel photocatalytic composite material method for the degradation of polyfluorinated organic pollutants, mainly including:
[0052] (1) The aqueous solution of polyfluorinated organic pollutants is used as a pollutant water sample, and the new photocatalytic composite material mSiO2@5% CeO2 prepared in Example 1 is added to the water sample;
[0053] (2) Under the irradiation of simulated sunlight and sunlight, visible light with a wavelength of 400 nm to 760 nm is used, and water samples are taken at intervals, and the catalyst is filtered with a filter membrane.
[0054] (3) The concentration change of the polyfluorinated organic pollutants is monitored by ultraviolet-visible spectroscopy or liquid chromatography.
[0055] The polyfluorinated organic pollutants in this embodiment include PFOA, PFOS, F-53B, OFB, DTMDEB, 3,4,5-trifluorobenzenboronic acid, 3,5-difluoroaniline, florfenicol.
[0056] In this embodiment, OFB is also used as a model substrate to explore the effects of different concentrations of the new photocatalytic composite material mSiO2@5% CeO2 and the pH in the degradation system on the degradation effect. The concentration of the new photocatalytic composite material is set to 1 g / L, 2.5 g / L, 3 g / L, and 5 g / L in multiple groups; the pH value of the solution in the degradation system is set to 3, 5, 7, and 9 in multiple groups. Figure 11 It can be seen that the concentration of the new photocatalytic composite material mSiO2@5% CeO2 is 2.5 g / L, and the degradation effect is best when the pH in the degradation system is 7.
[0057] The new photocatalytic composite material mSiO2@5% CeO2 of the application degrades fluorine-containing organic pollutants through adsorption-photocatalysis synergistic effect. CeO2 acts as a photocatalyst and plays a leading catalytic role. Its oxidation potential is 2.64 eV (VS NHE ) and e- and h+ are generated at both ends of the catalyst under light excitation. SiO2 plays a major adsorption role, so the synthesized mSiO2 with multiple mesopores can adsorb more organic pollutants, making them tightly adsorbed with the catalyst and accelerating the attack speed of active free radicals on organic pollutants in the photocatalysis process. Compared with general SiO2, it has more excellent adsorption capacity and can improve the photocatalytic degradation efficiency of polyfluorinated organic pollutants. In the process of photocatalytic degradation, the new photocatalytic composite material mSiO2@5% CeO2 of the application is excited by light, e- and h+ are generated at both ends of the catalyst, h+ with oxidizing property can react with water to generate hydroxyl radicals, and the hydroxyl radicals can assist in the oxidative degradation of pollutants. At the same time, SiO2 may combine with hydroxyl radicals and hydrogen ions, and Si-H and Si-OH bonds can be formed on the surface of SiO2. Since the stability of Si-F is greater than that of C-F, and the stability of C-H is greater than that of Si-H, hydrogenation defluorination is realized through Si-H / C-F redistribution, which can simultaneously degrade organic matter through photocatalysis and chemically combine fluorine ions through Si ions.
[0058] The degradation products were tracked by XPS and EDS characterization. As shown in Figure 6 XPS was used to characterize the different valence states and coordination of elements. The photocatalyst mSiO2@5% CeO2 had a characteristic peak of F after degradation. The signal at 684.9 eV was attributed to the characteristic signal of fluorine element. The crystal type derivation result also confirmed that F existed on the catalyst. The EDS element distribution maps of the catalyst before and after degradation were compared, as shown in Figure 7 It can be seen that F element is distributed on the surface of the catalyst after degradation. From Figure 17 The element content distribution maps of the photocatalytic composite mSiO2@5% CeO2 before and after degradation show that the content of fluorine element in the photocatalytic composite mSiO2@5% CeO2 after degradation increased to 2.48%. It is shown that the fluorine ion is not discharged outside after degradation, but is adsorbed on the surface of the catalyst.
[0059] 2. Degradation experiment results
[0060] (1) When the polyfluoro organic pollutant is OFB (polyfluoro biphenyl analogue), as shown in Figure 11 the concentration of the new photocatalytic composite mSiO2@5% CeO2 is 2 g / L, the pH in the degradation system is 7, under 400 nm visible light, 180 min, the degradation rate is 85%; under 300 W xenon lamp, 230 min, the degradation rate is 90%; under sunlight, 360 min, the degradation rate is 85%.
[0061] (2) When the polyfluoro organic pollutant is 4-[difluoro(3,4,5-trifluorophenoxy) methyl]-4'-ethyl-3,5-difluorobiphenyl (DTMEDB), as shown in Figure 12 the concentration of the new photocatalytic composite is 2 g / L, the pH is 7, under 400 nm visible light, 22 h, the degradation rate is 60%; under 300 W xenon lamp, 22 h, the degradation rate is 85%; under sunlight, 22 h, the degradation rate is 20%.
[0062] (3) When the polyfluoro organic pollutant is 3,4,5-trifluorophenylboric acid, as shown in Figure 13 the concentration of the new photocatalytic composite is 2 g / L, the pH is 7, under 400 nm visible light, 5 h, the degradation rate is 99%; under 300 W xenon lamp, 5 h, the degradation rate is 85%; under sunlight, 5 h, the degradation rate is 40%.
[0063] (4) When the polyfluoro organic pollutant is 3,5-difluoroaniline, as shown in Figure 14As shown, the concentration of the new photocatalytic composite material was 2 g / L, the pH was 7, under 400 nm visible light for 5 h, the degradation rate was 19%; under 300 W xenon lamp for 5 h, the degradation rate was 22%; under sunlight for 5 h, the degradation rate was 5%.
[0064] (5) When the polyfluoro organic pollutant was florfenicol, as shown in Figure 15 As shown, the concentration of the new photocatalytic composite material was 2 g / L, the pH was 7, under 400 nm visible light for 6 h, the degradation rate was 75%; under 300 W xenon lamp for 6 h, the degradation rate was 60%; under sunlight for 6 h, the degradation rate was 31%.
[0065] (6) When the polyfluoro organic pollutant was ciprofloxacin, as shown in Figure 16 As shown, the concentration of the new photocatalytic composite material was 2 g / L, the pH was 7, under 400 nm visible light for 6 h, the degradation rate was 75%; under 300 W xenon lamp for 6 h, the degradation rate was 60%; under sunlight for 6 h, the degradation rate was 31%.
[0066] (7) When the polyfluoro organic pollutant was perfluorooctanoic acid (PFOA), since perfluorooctanoic acid was an alkyl chain, the monitoring of its concentration needed to be taken by sampling at intervals, the catalyst in the water sample was filtered out by a filter membrane, and the clear solution was monitored for concentration change by liquid chromatography. The concentration of the new photocatalytic composite material was 2 g / L, the pH was 7, under 400 nm visible light for 48 h, the degradation rate was 12%; under 300 W xenon lamp for 48 h, the degradation rate was 15%; under sunlight for 48 h, the degradation rate was 5%.
[0067] (8) When the polyfluoro organic pollutant was perfluorooctane sulfonic acid (PFOS), the same as perfluorooctanoic acid (PFOA), the concentration change of PFOS was monitored by liquid chromatography. The concentration of the new photocatalytic composite material was 2 g / L, the pH was 7, under 400 nm visible light for 48 h, the degradation rate was 30%; under 300 W xenon lamp for 48 h, the degradation rate was 40%; under sunlight for 48 h, the degradation rate was 15%.
[0068] (9) When the polyfluoro organic pollutant was 2-[(6-chloro-1,1,2,2,3,3,4,4,5,5,6,6-dodecafluorohexyl)oxy]-1,1,2,2-tetrafluoroethane sulfonic acid potassium (F-53B), the same as perfluorooctanoic acid (PFOA), the concentration change of F-53B was monitored by liquid chromatography. The concentration of the new photocatalytic composite material was 2 g / L, the pH was 7, under 400 nm visible light for 36 h, the degradation rate was 20%; under 300 W xenon lamp for 36 h, the degradation rate was 27%; under sunlight for 36 h, the degradation rate was 10%.
[0069] The above degradation examples show the degradation strength of the photocatalyst composite material mSiO2@5% CeO2 on different polyfluorinated organic pollutants.
[0070] Comparative Example 1
[0071] Commercial 800 mesh silica gel powder (SiO2) was purchased and the commercial SiO2@CeO2 was synthesized by hydrothermal method. The specific synthesis method was similar to step (2) of Example 1. From Figure 10 It can be seen that the particle size of the commercial SiO2@CeO2 prepared in Comparative Example 1 is 10-20 uM, spherical shape, and the specific surface area is 230 m 2 g -1 .
[0072] Comparative Example 2
[0073] The photocatalyst composite material synthesized in Comparative Example 1 was used to degrade polyfluorinated organic pollutants by a method similar to Example 2.
[0074] Degradation experiment results
[0075] From Figure 8 It can be seen that the degradation effect of mSiO2@5% CeO2 synthesized in Example 1 on OFB is better than that of commercial SiO2@5% CeO2 synthesized by using commercial silica gel powder in Comparative Example 1. As can be seen, under the condition of 180 min and pH 7, the degradation rate of mSiO2@5% CeO2 on OFB is 85%, and the degradation rate of commercial SiO2@5% CeO2 on OFB is 15%. Similarly Figure 8 (c) it can be seen that for other fluorinated organic matter models, the catalytic effect of the mesoporous mSiO2 of the application is still better than that of the commercial SiO2, and the reason is that the mSiO2 synthesized in the example is a porous structure, and the specific surface area is large, which can adsorb more organic pollutants, thereby improving the degradation efficiency.
[0076] Obviously, the above examples of the application are only examples for clearly illustrating the application, and are not intended to limit the embodiments of the application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, it is not necessary and impossible to exhaust all the embodiments. Any modification, equivalent replacement and improvement made within the spirit and principle of the application shall be included in the protection scope of the claims of the application.
Claims
1. Use of a photocatalytic composite material, characterized in that, Degradation of polyfluoro organic pollutants The preparation method of the photocatalytic composite material comprises the following steps: (1) under room temperature conditions, tetraethyl orthosilicate, deionized water, ammonia, and hexadecyl trimethyl ammonium bromide are stirred uniformly to reach a gel state, repeatedly washed with deionized water, dried at 120-180 ℃ for 1-5 h, then physically and mechanically ground uniformly, calcined at 400-600 ℃ in a muffle furnace for 4-8 h to obtain mesoporous mSiO2; (2) after dissolving Ce(NO3)3·6H2O in deionized water, the mesoporous mSiO2 prepared in step (1) is added, water solvent is removed by a rotary evaporator under reduced pressure, the mixed product is dried for 10-20 h, then physically and mechanically ground uniformly, calcined at 250-300 ℃ in a muffle furnace for 1-4 h to obtain mSiO2@CeO2; In step (1), the molar ratio of tetraethyl orthosilicate, deionized water, ammonia, and hexadecyl trimethyl ammonium bromide is 0.01-1:1.6-3:0.015-0.1:0.002-0.8; In step (2), the molar ratio of Ce(NO3)3·6H2O added to the mesoporous mSiO2 is 1:
20.
2. Use according to claim 1, characterized in that, The polyfluoro organic pollutants include one or more of PFOA, PFOS, F-53B, OFB, 3,4,5-trifluorobenzenboronic acid, 3,5-difluoroaniline, florfenicol.
3. A method of degrading polyfluoroorganic pollutants by photocatalytic composite material, characterized in that, The method comprises the steps of: taking a polyfluoro organic pollutant aqueous solution as a pollutant water sample, adding the photocatalytic composite material to the water sample, and degrading the pollutant under visible light; The preparation method of the photocatalytic composite material comprises the following steps: (1) under room temperature conditions, tetraethyl orthosilicate, deionized water, ammonia, and hexadecyl trimethyl ammonium bromide are stirred uniformly to reach a gel state, repeatedly washed with deionized water, dried at 120-180 ℃ for 1-5 h, then physically and mechanically ground uniformly, calcined at 400-600 ℃ in a muffle furnace for 4-8 h to obtain mesoporous mSiO2; (2) after dissolving Ce(NO3)3·6H2O in deionized water, the mesoporous mSiO2 prepared in step (1) is added, water solvent is removed by a rotary evaporator under reduced pressure, the mixed product is dried for 10-20 h, then physically and mechanically ground uniformly, calcined at 250-300 ℃ in a muffle furnace for 1-4 h to obtain mSiO2@CeO2; In step (1), the molar ratio of tetraethyl orthosilicate, deionized water, ammonia, and hexadecyl trimethyl ammonium bromide is 0.01-1:1.6-3:0.015-0.1:0.002-0.8; In step (2), the molar ratio of Ce(NO3)3·6H2O added to the mesoporous mSiO2 is 1:
20.
4. The method of degrading polyfluoroorganic contaminants according to claim 3, wherein, The concentration of the photocatalytic composite material is 2.5 g / L.
5. The method of degrading a polyfluoroorganic contaminant according to claim 3, wherein, The pH of the pollutant water sample is 7.
6. The method of degrading a polyfluoroorganic contaminant according to claim 3, wherein, The visible light is one or more of a 400nm-760nm LED lamp, a 300W xenon lamp, and outdoor sunlight.