CN113058606A - Oxygen-enriched vacancy NaFeSi2O6Preparation of photocatalyst and method for photoreduction of Cr (VI) - Google Patents
Oxygen-enriched vacancy NaFeSi2O6Preparation of photocatalyst and method for photoreduction of Cr (VI) Download PDFInfo
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- 239000011941 photocatalyst Substances 0.000 title claims abstract description 51
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims abstract description 32
- 239000001301 oxygen Substances 0.000 title claims abstract description 32
- 229910052760 oxygen Inorganic materials 0.000 title claims abstract description 32
- 238000000034 method Methods 0.000 title claims abstract description 27
- 238000007540 photo-reduction reaction Methods 0.000 title claims abstract description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 39
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 23
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- 238000002360 preparation method Methods 0.000 claims abstract description 10
- SZQUEWJRBJDHSM-UHFFFAOYSA-N iron(3+);trinitrate;nonahydrate Chemical compound O.O.O.O.O.O.O.O.O.[Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O SZQUEWJRBJDHSM-UHFFFAOYSA-N 0.000 claims abstract description 5
- 239000000463 material Substances 0.000 claims abstract description 5
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 3
- 229910052742 iron Inorganic materials 0.000 claims abstract description 3
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 3
- 239000010703 silicon Substances 0.000 claims abstract description 3
- 238000000498 ball milling Methods 0.000 claims description 21
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 12
- 238000001035 drying Methods 0.000 claims description 11
- 239000000203 mixture Substances 0.000 claims description 9
- 229910007270 Si2O6 Inorganic materials 0.000 claims description 8
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 7
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 6
- 229910021260 NaFe Inorganic materials 0.000 claims description 6
- 238000003756 stirring Methods 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- 239000008367 deionised water Substances 0.000 claims description 4
- 229910021641 deionized water Inorganic materials 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 4
- 235000006408 oxalic acid Nutrition 0.000 claims description 4
- 238000007605 air drying Methods 0.000 claims description 3
- 238000001816 cooling Methods 0.000 claims description 3
- 238000005286 illumination Methods 0.000 claims description 3
- -1 polytetrafluoroethylene Polymers 0.000 claims description 3
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 3
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 3
- 230000001376 precipitating effect Effects 0.000 claims description 2
- 230000008569 process Effects 0.000 claims description 2
- 238000005406 washing Methods 0.000 claims description 2
- 230000001699 photocatalysis Effects 0.000 abstract description 13
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- 238000006722 reduction reaction Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
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- 238000004435 EPR spectroscopy Methods 0.000 description 2
- 239000005909 Kieselgur Substances 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 238000003795 desorption Methods 0.000 description 2
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- 239000000523 sample Substances 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- KSPIHGBHKVISFI-UHFFFAOYSA-N Diphenylcarbazide Chemical compound C=1C=CC=CC=1NNC(=O)NNC1=CC=CC=C1 KSPIHGBHKVISFI-UHFFFAOYSA-N 0.000 description 1
- 229910020489 SiO3 Inorganic materials 0.000 description 1
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- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 231100000086 high toxicity Toxicity 0.000 description 1
- 238000000713 high-energy ball milling Methods 0.000 description 1
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- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
- B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/78—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with alkali- or alkaline earth metals
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
- B01J35/39—Photocatalytic properties
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
- B01J35/61—Surface area
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/30—Treatment of water, waste water, or sewage by irradiation
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/20—Heavy metals or heavy metal compounds
- C02F2101/22—Chromium or chromium compounds, e.g. chromates
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2305/00—Use of specific compounds during water treatment
- C02F2305/10—Photocatalysts
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Abstract
Oxygen-enriched vacancy NaFeSi2O6A preparation method of a photocatalyst and a method for photo-reducing Cr (VI) belong to the technical field of new photocatalytic materials. The method comprises the following steps: the method comprises the steps of respectively taking diatomite and ferric nitrate nonahydrate as a silicon source and an iron source, and hydrothermally preparing NaFeSi in a NaOH solution2O6A photocatalyst. (2) Then NaFeSi is added2O6The photocatalyst is mechanically ball-milled to obtain NaFeSi with oxygen-rich vacancy2O6A photocatalyst. With NaFeSi2O6Carrying out photoreduction performance evaluation on Cr (VI) solution with the concentration of 70mg/L by the photocatalyst under visible light (lambda is more than or equal to 420 nm); the oxygen enrichment prepared by the inventionVacancy NaFeSi2O6The photocatalyst has the characteristics of mild conditions, simple operation, low cost, environmental friendliness, obvious performance improvement, easiness in large-scale mass production and the like, and has good development prospect and industrial application potential.
Description
Technical Field
The invention relates to the field of sewage treatment. In particular to NaFe with oxygen-rich vacancy2Si2O6The preparation of the photocatalyst and the efficient photoreduction of Cr (VI) belong to the field of new photocatalyst materials.
Background
The rapid development of the industry brings about the problem of serious water body pollution, wherein Cr (VI) heavy metal ions from the industries of electroplating, tanning, printing and dyeing and the like are the most extensive and serious, and due to the characteristics of high toxicity, difficult decomposition, easy enrichment in human bodies and the like of Cr (VI), Cr (VI) can be reduced into Cr (III) with lower toxicity. At present, the methods for removing Cr (VI) mainly comprise: chemical precipitation, adsorption, ion exchange, electrolysis, membrane separation, and semiconductor photocatalysis. The semiconductor photocatalysis technology is developed in recent years, and the technology for purifying the environment by utilizing solar energy has the advantages of renewable energy sources, environmental friendliness, low cost and the like.
The core of the photocatalytic technology is the design of the photocatalyst. The conventional photocatalyst has various disadvantages: such as high cost, poor stability, low activity and secondary pollution to the environment, which severely limits the application of the photocatalyst. Therefore, the search for a new photocatalyst is urgent. The silicate photocatalyst is a photocatalyst newly developed in recent years, is low in cost and rich in raw materials, is environment-friendly, and cannot generate secondary harm to the environment.
According to the reported ZnSiO4And Bi2O2SiO3The silicate photocatalyst has the defects of low activity, large forbidden band width, poor activity under visible light and the like, and can only be excited under ultraviolet light, so that the application of the silicate photocatalyst is severely limited. NaFe2Si2O6The photocatalyst also has the characteristics as a novel silicate photocatalyst, so that the NaFe can be further modified by a method for introducing oxygen vacancies2Si2O6A photocatalyst. Oxygen vacancies are currently introducedThe method mainly comprises the following steps: a heating hydrogenation method, an ion doping method, an atmosphere deoxidation method, a reducing agent reduction method and the like, and the methods have the characteristics of high cost, complex operation, harsh reaction conditions, certain dangerousness and the like. In order to avoid the defects of the method for introducing the oxygen vacancy, a method for introducing a large number of oxygen vacancies by a mechanical ball milling method is researched, so that the novel oxygen-enriched vacancy NaFeSi is prepared2O6A photocatalyst.
Disclosure of Invention
The invention aims to provide a method for preparing NaFe with rich oxygen-rich vacancy by a simple high-energy ball milling method2Si2O6(denoted as NFS) photocatalyst. Under visible light, the performance of the NFS photocatalyst is tested through the performance of photocatalytic reduction of Cr (VI), and the BM-NaFe oxygen-rich vacancy generated after ball milling is found2Si2O6(written as BM-NFS) photocatalyst ratio NaFe2Si2O6The activity of the photocatalyst is greatly improved.
The invention also aims to provide the BM-NFS photocatalyst with the oxygen-rich vacancy, which can effectively promote the separation of photogenerated electron holes, improve the light absorption range and the utilization rate and obviously improve the efficiency of the photocatalytic reduction of Cr (VI).
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
(1) respectively taking diatomite and ferric nitrate nonahydrate as a silicon source and an iron source, and hydrothermally preparing NaFeSi in a NaOH solution2O6A photocatalyst; then drying;
(2) then NaFeSi is added2O6NaFe from the photocatalyst to oxygen-rich vacancy after dry ball milling for a certain time2Si2O6A photocatalyst;
(3)NaFeSi2O6the photocatalyst reduces Cr (VI) into Cr (III) under illumination;
in the step 1), the mass ratio of the diatomite to the ferric nitrate nonahydrate is 1: 2.1-2.4.
The concentration of the sodium hydroxide solution in the step 1) is 40-60 g/L; 30-50ml of sodium hydroxide solution is added to every 0.45g of diatomite;
the hydrothermal condition in the step 1) is 180 ℃ and 30 hours.
The specific conditions for drying the product in step 1) are: placing the mixture into a forced air drying oven, and keeping the temperature for 12 hours at 60 ℃.
The specific operation steps of the step 1) are as follows: adding diatomite into a sodium hydroxide solution, stirring until the diatomite is completely dissolved, then adding ferric nitrate, and precipitating Fe (OH) generated by the reaction of the added ferric nitrate and NaOH to the surface of the diatomite; transferring the mixture into a polytetrafluoroethylene lining in a high-pressure reaction kettle, then putting the mixture into a blast drying oven, heating to 180 ℃, and keeping the temperature for 30 hours. After cooling to room temperature, the mixture was washed several times with deionized water and ethanol. Drying the yellow-green product.
Step 1) diatomaceous earth is further pretreated:
in the step 2), the ball milling conditions are that the ball-material ratio is 50:1, the rotating speed is 300rpm, and the ball milling time is 30 min.
In the step 3), the illumination condition is (lambda is more than or equal to 420nm) and the concentration of Cr (VI) is 70 mg/L. The conditions for photocatalytic reduction of Cr (VI) are as follows: 15mg of photocatalyst, 50mL of a 70mg/L Cr (VI) solution, and 30mg of oxalic acid.
The invention aims to provide simple and large-scale production of NaFeSi with oxygen-enriched vacancy2O6The method adopts a simple mechanical ball milling method, can effectively and obviously improve the concentration distribution of oxygen vacancies, improve the separation efficiency of electron holes and reduce the recombination rate of the electron holes; the photocatalyst prepared by the method has good photoelectric property and Cr (VI) photocatalytic reduction property. Oxygen-enriched vacancy NaFeSi prepared by the invention2O6The photocatalyst has the characteristics of mild conditions, simple operation, low cost, environmental friendliness, obvious performance improvement, easiness in large-scale mass production and the like, and has good development prospect and industrial application potential.
Drawings
FIG. 1 is an X-ray diffraction pattern of NFS and BM-NFS in examples;
FIG. 2 is a scanning electron micrograph of NFS (a) and BM-NFS (b) in example;
FIG. 3 is a graph of the UV-VIS diffuse reflectance absorption spectra of the NFS and BM-NFS of the examples;
FIG. 4 is a spectrum of forbidden band widths of NFS and BM-NFS in the example;
FIG. 5 is a plot of nitrogen adsorption-desorption isotherms of NFS and BM-NFS in examples;
FIG. 6 is electron paramagnetic resonance spectra of NFS and BM-NFS of the examples;
FIG. 7 shows the photo-reduced Cr (VI) activity spectra of NFS and BM-NFS in examples.
Detailed Description
The present invention will be further illustrated with reference to the following examples, but the present invention is not limited to the following examples.
1): pretreatment of diatomite: continuously stirring diatomite in a dilute sulfuric acid solution for 5 hours, continuously washing the diatomite to be neutral by deionized water, drying the diatomite for 24 hours at the temperature of 60 ℃, and then reserving the diatomite for later use.
0.45g of diatomaceous earth and 2.0g of NaOH were added to 40ml of ultrapure water, and the mixture was stirred for 1 hour.
2) While the mixed solution obtained in step 1) was continuously stirred, 1.010g of Fe (NO) was added3)3·9H2Slowly adding O powder into the mixed solution obtained in the step 1), and continuously stirring for 1h to ensure that Fe (NO) is added3)3·9H2The reaction of the O powder and NaOH completely generates Fe (OH) and precipitates to the surface of the diatomite.
3) Transferring the mixed liquid raw material obtained in the step 2) to a polytetrafluoroethylene lining in a high-pressure reaction kettle, then putting the mixed liquid raw material into a blast drying oven, heating to 180 ℃, and keeping for 30 hours. After cooling to room temperature, the mixture was washed several times with deionized water and ethanol. Drying the yellow-green sample in a forced air drying oven at 60 ℃ for 12h, and collecting the sample to obtain NaFeSi2O6(NFS) photocatalyst.
4) Weighing 0.2g of NaFeSi prepared in step 3)2O6Putting the powder into a ball milling tank, putting 20 agate balls with the diameter of 7.0mm into the ball milling tank, wherein the ball-to-material ratio in the ball milling tank is about 50:1, and carrying out ball milling for 30min at the rotating speed of 300rpm to obtain the NaFeSi with oxygen-rich vacancy2O6(BM-NFS) photocatalyst
5) Measurement of photocatalytic performance: in a 100ml beaker, 15mg of photocatalyst and 30mg of oxalic acid were added to 50ml of a 70mg/L Cr (VI) solution. Before light, stir in dark for 20min to reach adsorption and desorption equilibrium. Then the mixed solution was placed under a xenon lamp, and 2.6ml of the solution was taken every 10min under irradiation with visible light (. lamda.gtoreq.420 nm), and the change in the Cr (VI) concentration in the solution was measured by removing the powder with a 0.22 μm filter head. The Cr (VI) concentration change is measured by a DPC color-developing method, diphenylcarbazide is used as a color-developing agent, and the concentration of the photo-reduced Cr (VI) is measured by a UV-3600Plus Shimadzu UV-visible spectrophotometer at a wavelength of 540 nm.
FIG. 1 is an XRD spectrum of NFS and BM-NFS. As can be seen, the diffraction peak positions of the prepared NFS and BM-NFS are located at 13.9, 20.0, 29.9, 30.8, 35.5, 36.3, 41.0 and 42.7, respectively, which correspond to the (110), (-111), (-221), (310), (002), (221), (040) and (330) crystal planes of the NFS standard pdf card, respectively, indicating that the NFS photocatalyst was successfully prepared. Compared with NFS, BM-NFS diffraction peak intensity is obviously reduced because the chemical structure of NFS is changed in the ball milling process, so that crystallinity is weakened, and the XRD spectrum structure shows that the ball milling can reduce the crystallinity of NFS.
FIG. 2 is an SEM image of NFS and BM-NFS. As can be seen, the NFS topography is unique needle-bundle shaped and is superimposed and clustered together, with each bundle having a dimension length of about 2 μm. After ball milling is carried out on the NFS, the morphology is greatly changed, and the BM-NFS is changed into a random spherical shape from a needle bundle shape.
FIG. 3 is N of NFS and BM-NFS2Adsorption and desorption isotherm spectrogram. As can be seen from the figure, the specific surface areas of NFS and BM-NFS are 21.297 and 38.007m, respectively2(ii) in terms of/g. The significant increase in specific surface area of BM-NFS after ball milling compared to NFS is due to the increase in specific surface area due to morphology change and grain refinement that occurs during ball milling.
FIG. 4 is an EPR diagram of NFS and BM-NFS. From the figure, it can be seen that the EPR signal of the ball-milled BM-NFS is significantly enhanced, indicating that more oxygen vacancy defects are present in the BM-NFS.
FIG. 5 is a UV-visible diffuse reflectance spectrum of NFS and BM-NFS. As can be seen from the figure, compared with NFS, the ultraviolet-visible diffuse reflectance spectrum of the ball-milled BM-NFS undergoes obvious blue shift, and the light absorption range is widened, which is caused by more oxygen defects generated on the surface of the BM-NFS.
Fig. 6 is a diagram of forbidden bandwidths of NFS and BM-NFS. It can be seen that the BM-NFS band gap after ball milling is narrowed from 2.49eV to 2.41 eV.
FIG. 7 is a graph of the activity of photocatalytic reduction of Cr (VI) for NFS and BM-NFS and blank samples. Under the irradiation condition of visible light (lambda is more than or equal to 420nm), oxalic acid is used as a hole trapping agent, the photoreduction rate of Cr (VI) by NFS photocatalysis without ball milling in 30min reaches 13%, and the photocatalytic rate of Cr (VI) by BM-NFS photocatalyst after ball milling in 30min reaches 99%, which shows that the BM-NFS has excellent performance of photocatalytic reduction of Cr (VI).
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and all modifications and variations made according to the spirit of the present invention are included in the scope of the present invention.
Claims (10)
1. Oxygen-enriched vacancy NaFeSi2O6The preparation method of the photocatalyst is characterized by comprising the following steps:
(1) the method comprises the steps of respectively taking diatomite and ferric nitrate nonahydrate as a silicon source and an iron source, and hydrothermally preparing NaFeSi in a NaOH solution2O6A photocatalyst; then drying;
(2) then NaFeSi is added2O6NaFe from the photocatalyst to oxygen-rich vacancy after dry ball milling for a certain time2Si2O6A photocatalyst.
2. An oxygen-rich vacancy NaFeSi as claimed in claim 12O6The preparation method of the photocatalyst is characterized in that the mass ratio of the diatomite to the ferric nitrate nonahydrate in the step 1) is 1: 2.1-2.4.
3. An oxygen-rich vacancy NaFeSi as claimed in claim 12O6Photocatalyst and process for producing the sameThe preparation method is characterized in that the concentration of the sodium hydroxide solution in the step 1) is 40-60 g/L; each 0.45g of diatomite corresponds to 30-50ml of the volume of the sodium hydroxide solution.
4. An oxygen-rich vacancy NaFeSi as claimed in claim 12O6The preparation method of the photocatalyst is characterized in that the hydrothermal condition in the step 1) is 180 ℃ for 30 hours.
5. An oxygen-rich vacancy NaFeSi as claimed in claim 12O6The preparation method of the photocatalyst is characterized in that the specific conditions for drying the product in the step 1) are as follows: placing the mixture into a forced air drying oven, and keeping the temperature for 12 hours at 60 ℃.
6. An oxygen-rich vacancy NaFeSi as claimed in claim 12O6The preparation method of the photocatalyst is characterized in that the specific operation steps in the step 1) are as follows: adding diatomite into a sodium hydroxide solution, stirring until the diatomite is completely dissolved, then adding ferric nitrate, and precipitating Fe (OH) generated by the reaction of the added ferric nitrate and NaOH to the surface of the diatomite; transferring the mixture into a polytetrafluoroethylene lining in a high-pressure reaction kettle, then putting the mixture into a blast drying oven, heating to 180 ℃, and keeping the temperature for 30 hours; after cooling to room temperature, washing with deionized water and ethanol for several times; drying the yellow-green product.
7. An oxygen-rich vacancy NaFeSi as claimed in claim 12O6The preparation method of the photocatalyst is characterized in that the diatomite in the step 1) is further pretreated.
8. An oxygen-rich vacancy NaFeSi as claimed in claim 12O6The preparation method of the photocatalyst is characterized in that the ball milling condition in the step 2) is that the ball-to-material ratio is 50:1, the rotating speed is 300rpm, and the ball milling time is 30 min.
9. Oxygen-rich vacancy NaFeSi prepared by the method of any one of claims 1 to 82O6A photocatalyst.
10. Oxygen-rich vacancy NaFeSi prepared by the method of any one of claims 1 to 82O6The application of the photocatalyst is that Cr (VI) is subjected to photoreduction under the illumination condition that lambda is more than or equal to 420nm and the concentration of Cr (VI) is 70 mg/L; while oxalic acid is added.
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