CN112642463B - Visible light catalyst for degrading dye in wastewater, preparation method and application thereof - Google Patents
Visible light catalyst for degrading dye in wastewater, preparation method and application thereof Download PDFInfo
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- CN112642463B CN112642463B CN202011644611.1A CN202011644611A CN112642463B CN 112642463 B CN112642463 B CN 112642463B CN 202011644611 A CN202011644611 A CN 202011644611A CN 112642463 B CN112642463 B CN 112642463B
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- 239000003054 catalyst Substances 0.000 title claims abstract description 32
- 238000002360 preparation method Methods 0.000 title claims abstract description 23
- 239000002351 wastewater Substances 0.000 title claims abstract description 22
- 230000000593 degrading effect Effects 0.000 title claims abstract description 14
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 206
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 103
- HZNPCLUBXJLRAA-UHFFFAOYSA-N iron;oxomolybdenum Chemical compound [Fe].[Mo]=O HZNPCLUBXJLRAA-UHFFFAOYSA-N 0.000 claims abstract description 28
- 239000011941 photocatalyst Substances 0.000 claims abstract description 12
- 229940043267 rhodamine b Drugs 0.000 claims description 83
- PYWVYCXTNDRMGF-UHFFFAOYSA-N rhodamine B Chemical compound [Cl-].C=12C=CC(=[N+](CC)CC)C=C2OC2=CC(N(CC)CC)=CC=C2C=1C1=CC=CC=C1C(O)=O PYWVYCXTNDRMGF-UHFFFAOYSA-N 0.000 claims description 82
- 239000000843 powder Substances 0.000 claims description 76
- 239000000243 solution Substances 0.000 claims description 73
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 66
- 229910002804 graphite Inorganic materials 0.000 claims description 64
- 239000010439 graphite Substances 0.000 claims description 64
- 239000002131 composite material Substances 0.000 claims description 63
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 59
- 238000009210 therapy by ultrasound Methods 0.000 claims description 48
- 229910021642 ultra pure water Inorganic materials 0.000 claims description 46
- 239000012498 ultrapure water Substances 0.000 claims description 46
- 239000007787 solid Substances 0.000 claims description 44
- APUPEJJSWDHEBO-UHFFFAOYSA-P ammonium molybdate Chemical compound [NH4+].[NH4+].[O-][Mo]([O-])(=O)=O APUPEJJSWDHEBO-UHFFFAOYSA-P 0.000 claims description 38
- 229940010552 ammonium molybdate Drugs 0.000 claims description 38
- 235000018660 ammonium molybdate Nutrition 0.000 claims description 38
- 239000011609 ammonium molybdate Substances 0.000 claims description 38
- 238000001354 calcination Methods 0.000 claims description 34
- 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 28
- 238000000227 grinding Methods 0.000 claims description 27
- 239000007864 aqueous solution Substances 0.000 claims description 23
- 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 description 22
- 230000001699 photocatalysis Effects 0.000 claims description 18
- 229920000877 Melamine resin Polymers 0.000 claims description 16
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 claims description 16
- 239000000975 dye Substances 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 15
- 238000001816 cooling Methods 0.000 claims description 14
- 238000004108 freeze drying Methods 0.000 claims description 14
- 229910052724 xenon Inorganic materials 0.000 claims description 13
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 claims description 13
- 238000001027 hydrothermal synthesis Methods 0.000 claims description 7
- 239000000725 suspension Substances 0.000 claims description 6
- 238000003756 stirring Methods 0.000 claims description 4
- 230000035484 reaction time Effects 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 1
- 238000006731 degradation reaction Methods 0.000 abstract description 57
- 230000015556 catabolic process Effects 0.000 abstract description 55
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 24
- 230000007547 defect Effects 0.000 abstract description 3
- 229910052751 metal Inorganic materials 0.000 abstract description 3
- 239000002184 metal Substances 0.000 abstract description 3
- 229910000476 molybdenum oxide Inorganic materials 0.000 abstract description 3
- 230000004043 responsiveness Effects 0.000 abstract 1
- 239000006228 supernatant Substances 0.000 description 33
- 230000000052 comparative effect Effects 0.000 description 21
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- 238000003760 magnetic stirring Methods 0.000 description 11
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- 238000000870 ultraviolet spectroscopy Methods 0.000 description 11
- 230000003197 catalytic effect Effects 0.000 description 10
- 239000006185 dispersion Substances 0.000 description 9
- 239000012265 solid product Substances 0.000 description 9
- 238000010438 heat treatment Methods 0.000 description 8
- 238000002156 mixing Methods 0.000 description 8
- 238000000527 sonication Methods 0.000 description 8
- 238000005406 washing Methods 0.000 description 8
- 239000010865 sewage Substances 0.000 description 6
- 238000007146 photocatalysis Methods 0.000 description 5
- 239000000126 substance Substances 0.000 description 4
- 238000000862 absorption spectrum Methods 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 229910044991 metal oxide Inorganic materials 0.000 description 3
- 150000004706 metal oxides Chemical class 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000839 emulsion Substances 0.000 description 2
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- 239000008188 pellet Substances 0.000 description 2
- 238000001782 photodegradation Methods 0.000 description 2
- 239000013535 sea water Substances 0.000 description 2
- GJCOSYZMQJWQCA-UHFFFAOYSA-N 9H-xanthene Chemical compound C1=CC=C2CC3=CC=CC=C3OC2=C1 GJCOSYZMQJWQCA-UHFFFAOYSA-N 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- 239000012028 Fenton's reagent Substances 0.000 description 1
- OWYWGLHRNBIFJP-UHFFFAOYSA-N Ipazine Chemical group CCN(CC)C1=NC(Cl)=NC(NC(C)C)=N1 OWYWGLHRNBIFJP-UHFFFAOYSA-N 0.000 description 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 241001465754 Metazoa Species 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 239000000981 basic dye Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000013505 freshwater Substances 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 238000010335 hydrothermal treatment Methods 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- DSMZRNNAYQIMOM-UHFFFAOYSA-N iron molybdenum Chemical compound [Fe].[Fe].[Mo] DSMZRNNAYQIMOM-UHFFFAOYSA-N 0.000 description 1
- QZRHHEURPZONJU-UHFFFAOYSA-N iron(2+) dinitrate nonahydrate Chemical compound O.O.O.O.O.O.O.O.O.[Fe+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O QZRHHEURPZONJU-UHFFFAOYSA-N 0.000 description 1
- QDLAGTHXVHQKRE-UHFFFAOYSA-N lichenxanthone Natural products COC1=CC(O)=C2C(=O)C3=C(C)C=C(OC)C=C3OC2=C1 QDLAGTHXVHQKRE-UHFFFAOYSA-N 0.000 description 1
- 238000013048 microbiological method Methods 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- JMANVNJQNLATNU-UHFFFAOYSA-N oxalonitrile Chemical compound N#CC#N JMANVNJQNLATNU-UHFFFAOYSA-N 0.000 description 1
- 239000000575 pesticide Substances 0.000 description 1
- 238000011197 physicochemical method Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000006862 quantum yield reaction Methods 0.000 description 1
- 150000003254 radicals Chemical class 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000005215 recombination Methods 0.000 description 1
- 230000006798 recombination Effects 0.000 description 1
- 238000004626 scanning electron microscopy Methods 0.000 description 1
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- 238000003911 water pollution Methods 0.000 description 1
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/24—Nitrogen compounds
-
- 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
-
- 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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
-
- 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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
- B01J37/10—Heat treatment in the presence of water, e.g. steam
-
- 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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/34—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation
- B01J37/341—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation
- B01J37/343—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of electric or magnetic fields, wave energy or particle radiation of ultrasonic wave energy
-
- 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
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/722—Oxidation by peroxides
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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
- C02F1/72—Treatment of water, waste water, or sewage by oxidation
- C02F1/725—Treatment of water, waste water, or sewage by oxidation by catalytic oxidation
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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
- C02F2101/30—Organic compounds
- C02F2101/308—Dyes; Colorants; Fluorescent agents
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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
- C02F2101/30—Organic compounds
- C02F2101/34—Organic compounds containing oxygen
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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
- C02F2101/30—Organic compounds
- C02F2101/36—Organic compounds containing halogen
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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
- C02F2101/30—Organic compounds
- C02F2101/38—Organic compounds containing nitrogen
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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
- C02F2305/02—Specific form of oxidant
- C02F2305/023—Reactive oxygen species, singlet oxygen, OH radical
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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
- C02F2305/02—Specific form of oxidant
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Abstract
The invention relates to a visible light catalyst for degrading dye in water, a preparation method and application thereof. The visible light catalyst takes lamellar graphite-phase nitrogen carbide as a main body, iron-molybdenum oxide is loaded on the lamellar graphite-phase nitrogen carbide, and the mass fraction of the iron-molybdenum oxide is 10-40% based on the mass of the graphite-phase nitrogen carbide. The preparation method comprises the steps of preparing lamellar graphite-phase nitrogen carbide, and doping the graphite-phase nitrogen carbide with metal oxide-iron-molybdenum oxide. The preparation method overcomes the defects of complex preparation process, long degradation time and the like in the prior art, has simple preparation method, simple and convenient degradation operation, high degradation efficiency, short degradation time and low cost, and can prepare the photocatalyst which has visible light responsiveness and can degrade the dye in the wastewater.
Description
Technical Field
The invention relates to a visible light catalyst for degrading dye in water, a preparation method and application thereof, belonging to the technical field of photocatalysis.
Background
At present, the existing water resources are seriously short, and particularly the water quality is seriously short. Therefore, in order to alleviate the situation that the fresh water resource is increasingly deficient, the utilization of the seawater resource is one of effective means. However, with the development of society, the types and discharge amount of domestic sewage, industrial sewage and agricultural sewage are increasing, and harmful substances such as inorganic heavy metal ions, pesticides and organic dyes in the sewage have extremely serious influence on the environment. Among them, dye-contaminated water is a relatively troublesome water pollution. If the dye wastewater enters a river without being treated, the dye wastewater threatens living conditions of plants, animals and microorganisms in the water body, thereby causing the water body to deteriorate. And also causes serious troubles in the utilization of seawater. At present, the treatment methods for such sewage mainly include physicochemical methods and microbiological methods. Due to the characteristics of dark color, strong toxicity, difficult degradation and the like of dye sewage, the photocatalytic technology has great application value by virtue of the advantages of stability, high efficiency, low cost and no secondary pollution.
In various types of wastewater, rhodamine b (rhb) is a typical severely harmful xanthene basic dye. The main methods for degrading the RhB dye comprise an ultrasonic chemical method, a Fenton reagent degradation method, a photocatalysis technology and the like. However, the whole degradation process in the prior art is complex, the operation is not simple and convenient, a plurality of catalysts are needed for degradation, and the time consumption of the degradation process is long.
Disclosure of Invention
Technical problem to be solved
In order to solve the defects of complex preparation process, long degradation time and the like in the prior art, the invention provides a visible-light-driven photocatalyst for degrading dye in wastewater.
(II) technical scheme
In order to achieve the purpose, the invention adopts the main technical scheme that:
a visible light catalyst for degrading dye in wastewater takes lamellar graphite-phase nitrogen carbide as a main body, iron-molybdenum oxide is loaded on the lamellar graphite-phase nitrogen carbide, the lamellar graphite-phase nitrogen carbide and the iron-molybdenum oxide form a heterojunction structure, and the mass fraction of the iron-molybdenum oxide is 10-40% of the mass of the graphite-phase nitrogen carbide based on the mass of the graphite-phase nitrogen carbide.
As described above for the visible light photocatalyst, preferably, the degradation dye is rhodamine B.
The preparation method of the visible light photocatalyst comprises the following steps:
s1, dispersing lamellar graphite phase nitrogen carbide in ultrapure water, and performing ultrasonic treatment to uniformly disperse the lamellar graphite phase nitrogen carbide;
s2, dissolving ammonium molybdate powder in ultrapure water, performing ultrasonic treatment to completely dissolve the ammonium molybdate powder to obtain a clear and transparent solution, putting ferric nitrate nonahydrate solid into the solution, continuing ultrasonic treatment until ferric nitrate is completely dissolved, and standing for the solution to be solidified into a gel state;
s3, freeze-drying the gel obtained in the step S2 to obtain a yellow-green block solid, and grinding to obtain yellow-green powder A;
s4, dissolving the powder A in ultrapure water, and performing ultrasonic treatment to obtain an orange-red transparent solution;
s5, adding the lamellar graphite-phase nitrogen carbide solution obtained in the step S1 into the orange-red transparent solution obtained in the step S4, adding ultrapure water to enable the solute concentration to reach 0.5-1 g/L, and performing ultrasonic treatment to obtain uniformly dispersed suspension; and carrying out hydrothermal reaction on the suspension to obtain the photocatalytic composite material.
In the above preparation method, preferably, in step S1, the method for preparing lamellar graphite phase nitrogen carbide is: and calcining melamine for the first time at the temperature of 500-600 ℃ for 3-5 h to obtain blocky graphite phase nitrogen carbide, cooling, grinding into powder, and continuing to calcine for the second time at the temperature of 500-550 ℃ for 1.5-3 h to obtain lamellar graphite phase nitrogen carbide.
Further, the temperature of the first calcination is preferably 550 ℃, and the calcination time is preferably 4 h;
the temperature of the second calcination is preferably 530 ℃, and the calcination time is preferably 2 h.
In the above preparation method, preferably, in step S2, the ammonium molybdate powder and the ferric nitrate nonahydrate are added in a mass ratio of 2:1 to 1: 2; dissolving the ammonium molybdate in ultrapure water to ensure that the concentration of ammonium molybdate solute reaches 0.1-0.5 mol/L.
Further, the ratio of the amount of the ammonium molybdate powder to the amount of the substance of iron nitrate nonahydrate is preferably performed in 1: 1.
In the preparation method described above, preferably, in step S4, the amount of the powder a is such that the ratio of graphite-phase nitrogen carbide to powder a in a mass ratio of 10: 1-10: and 4, carrying out.
In the preparation method, in step S5, the hydrothermal reaction temperature is preferably 140 to 170 ℃ and the hydrothermal time is preferably 5 to 7 hours.
Further, the hydrothermal reaction temperature is preferably 160 ℃ and the time is preferably 6 hours.
Further, numerous experiments have shown that the sonication time is such that the catalyst is completely dispersed without visible precipitation. As long as the catalyst is completely dispersed, the sonication time does not affect.
The visible light catalyst or the visible light catalyst obtained by the preparation method is applied to degrading rhodamine B in wastewater.
The application comprises the steps of adding the visible-light-driven photocatalyst and hydrogen peroxide into an aqueous solution containing rhodamine B, and stirring for 5-90 min under the irradiation of a xenon lamp light source with the wavelength of more than or equal to 400 nm. In the application, the final concentration of the visible-light-driven photocatalyst in the wastewater is preferably more than or equal to 6.25 mu g/mL, and the final concentration of the hydrogen peroxide in the wastewater is preferably 2-20 mmol/L.
Further, the reaction time is preferably 30-90 min, and the final concentration of hydrogen peroxide is preferably 10-20 mmol/L.
After photocatalytic degradation experiments, when the mass fraction of the iron-molybdenum oxide is 30%, the optimal photocatalytic composite material is obtained.
(III) advantageous effects
The invention has the beneficial effects that:
in the method for preparing the visible-light-driven photocatalyst for degrading the dye in the wastewater, compared with the blocky graphite-phase nitrogen carbide, the specific surface area of the adopted lamellar graphite-phase nitrogen carbide is obviously increased, so that the photocatalytic efficiency is greatly improved. Meanwhile, the lamellar graphite phase nitrogen carbide has larger specific surface area and thinner thickness, and can be uniformly dispersed in the aqueous solution so as to improve the absorptivity of light.
In the process of doping metal oxide-iron molybdenum oxide on graphite-phase nitrogen carbide, on one hand, a heterojunction structure can be formed between the graphite-phase nitrogen carbide and the iron molybdenum oxide, the heterojunction structure can effectively improve the separation efficiency of electrons and holes, inhibit the recombination of photoproduction electrons and holes, and improve the quantum yield, so that the photocatalysis efficiency of the composite material is improved, and on the other hand, due to the existence of iron element, the oxide can perform Fenton reaction with hydrogen peroxide, so that the content of hydroxyl free radicals is increased, and the photocatalysis degradation efficiency is improved.
The visible light catalyst provided by the invention can be used for photocatalytic degradation of rhodamine B in wastewater under the irradiation of visible light, the reaction condition is mild, the raw material cost is low, and the synthesis is simple and convenient and easy to realize.
The preparation method of the visible-light-driven photocatalyst for degrading the dye in the wastewater provided by the invention overcomes the defects of complex preparation process, long degradation time and the like in the prior art, is simple and convenient to degrade, has high degradation efficiency, short degradation time and low cost, and can be used for producing the visible-light-responsive photocatalyst for degrading the dye in the wastewater.
Drawings
FIG. 1 shows 100. mu.g/ml of graphite-phase bulk carbon nitride (C)3N4) And the ultraviolet-visible absorption spectrum of lamellar graphite phase nitrogen carbide;
FIG. 2 is a graph of 80mg bulk graphite phase nitrogen carbide (left) and 80mg lamellar graphite phase nitrogen carbide (right) volumes;
FIG. 3 shows a composite material (FMO/C) loaded with iron molybdenum oxide3N4) XRD of (1);
FIG. 4 is an infrared absorption spectrum of a composite material loaded with iron molybdenum oxide;
FIG. 5 shows a sheet C3N4Scanning electron microscope images of;
FIG. 6 shows a composite material (FMO/C) supporting iron molybdenum oxide3N4) Scanning electron microscope images of;
FIG. 7 is a UV-VIS absorption curve of the composite material degrading rhodamine B over time in example 1;
FIG. 8 is a photo-degradation curve of rhodamine B at different hydrogen peroxide concentrations or different catalyst concentrations in example 3 and example 8;
FIG. 9 is a photo-degradation curve of rhodamine B in comparative examples 1-3;
FIG. 10 is a photograph of melamine powders obtained after lyophilization in comparative example 4 (FIG. left) and in comparative example 5 (FIG. right);
fig. 11 is a photograph of the composites obtained by direct calcination of comparative example 4 (left panel) and comparative example 5 (right panel).
Fig. 12 is a photograph of composite powders obtained after calcination and grinding of comparative example 4 (left side of the figure) and comparative example 5 (right side of the figure).
Detailed Description
For the purpose of better explaining the present invention and to facilitate understanding, the present invention will be described in detail by way of specific embodiments with reference to the accompanying drawings.
Example 1
1. And (2) placing melamine in a tubular furnace, calcining at 550 ℃ for 4h to obtain blocky graphite phase nitrogen carbide, cooling, grinding into powder, paving into a thin layer in a crucible, placing the layer into a muffle furnace, and continuously calcining at 530 ℃ for 2h to obtain lamellar graphite phase nitrogen carbide. 10mg of the lamellar graphite-phase nitrogen carbide obtained above was dispersed in 2mL of ultrapure water, and the dispersion was made uniform by ultrasonic treatment.
2. Dissolving ammonium molybdate powder in ultrapure water, performing ultrasonic treatment to completely dissolve the ammonium molybdate powder to obtain a clear and transparent solution, adding ferric nitrate nonahydrate solid into the solution, continuing ultrasonic treatment until the ferric nitrate is completely dissolved, and standing for the solution to be solidified into a gel state. Wherein the mass ratio of ammonium molybdate powder to ferric nitrate nonahydrate solid is 1: 1.
3. Freeze drying the gel to obtain yellow green block solid, and grinding to obtain yellow green powder A.
4. Then 1mg of powder a was dissolved in 1mL of water and sonicated to dissolve it completely to give an orange-red clear and transparent solution.
5. Mixing graphite phase nitrogen carbide water solution and orange-red clear transparent solution, and performing ultrasonic treatment for 30min to mix them uniformly. Then transferred to the autoclave and added to increase the volume of the solution to 10mL, shaken up. Heating the mixture in a heater at 160 ℃ for 6 hours to carry out hydrothermal reaction. After the reaction is finished, removing the upper-layer aqueous solution by using a liquid-transferring gun, and then washing the lower-layer solid product for multiple times by using ultrapure water, wherein the obtained lower-layer solid product takes lamellar graphite-phase nitrogen carbide as a main body, and a metal oxide-iron-molybdenum oxide is loaded on the main body. The composite material with the iron-molybdenum oxide mass fraction of 10% is the visible light photocatalysis composite material, and finally 5mL of ultrapure water is added for storage and standby.
The ultraviolet-visible absorption light of the lamellar graphite phase nitrogen carbide prepared by the present invention and the bulk graphite phase nitrogen carbide (see comparative example 1 for the preparation method) was measured, and the results are shown in fig. 1 as the ultraviolet-visible absorption spectra of 100 μ g/ml of the bulk graphite phase nitrogen carbide and the lamellar graphite phase nitrogen carbide. The result shows that the absorptivity of the lamellar graphite phase nitrogen carbide prepared by the method for preparing the lamellar graphite phase nitrogen carbide is far greater than that of the massive graphite phase nitrogen carbide. This is one of the reasons why the photocatalytic efficiency of the composite material prepared by the present invention to obtain lamellar graphite-phase carbon is high.
FIG. 2 shows the volume of 80mg of bulk graphite phase nitrogen carbide (left) and 80mg of lamellar graphite phase nitrogen carbide (right). The volume of the lamellar graphite phase nitrogen carbide is far larger than that of the blocky graphite phase nitrogen carbide, which indicates that the lamellar graphite phase nitrogen carbide has larger specific surface area. The larger specific surface area allows the lamellar graphite phase carbon to be dispersed in water to a better degree.
The iron-molybdenum oxide-loaded composite material (FMO/C) prepared in this example was used3N4) And sheet C3N4X-ray diffraction was performed, and the result was XRD as shown in FIG. 3. The result shows that the lamellar graphite phase nitrogen carbide still retains two crystal lattices, and the composite material loaded with the iron-molybdenum oxide has the crystal lattices of the iron-molybdenum oxide besides the crystal lattices of the graphite phase nitrogen carbide, so that the iron-molybdenum oxide is successfully loaded to form a heterojunction structure.
The iron-molybdenum oxide-loaded composite material (FMO/C) prepared in this example was used3N4) And sheet C3N4The infrared absorption test was performed, and the results are shown in fig. 4, which indicates that neither the secondary calcination nor the hydrothermal treatment destroyed the structure of the heptazine ring of the graphite phase nitrogen carbide.
The pellets C prepared in this example were cut into pellets3N4Composite material (FMO/C) with supported iron molybdenum oxide3N4) Scanning electron microscopy showed that, as shown in FIGS. 5 and 6, the scale of FIG. 5 is a 1.00 μm plate C3N4Scanning an image by an electron microscope,FIG. 6 shows a 500nm FMO/C scale3N4Scanning Electron microscope, sheet C3N4The surface is only wrinkled, and granular substances exist on the surface of the composite material loaded with the iron-molybdenum oxide, namely the iron-molybdenum oxide, which indicates that the iron-molybdenum oxide is successfully loaded on the flaky C3N4And forming a heterojunction structure on the surface.
And (3) performance testing: taking 150 mu L of the composite material (FMO/C) with the mass fraction of the prepared iron-molybdenum oxide being 10 percent3N4) Adding 20mL of rhodamine B aqueous solution (the final concentration of rhodamine B is 5ppm), then adding 40 mu L of hydrogen peroxide solution (the final concentration of hydrogen peroxide is 20mmol/L), and standing at room temperature for 30min to ensure that the composite material has equilibrium adsorption on rhodamine B; then a 300W xenon lamp light source (lambda max) is used under magnetic stirring>400nm) was illuminated (lamp 20cm from sample) and a timer was started. Sampling at certain time intervals, centrifuging, taking supernatant, measuring the absorbance of the supernatant at the maximum absorption wavelength of rhodamine B by using an ultraviolet-visible spectrophotometer, and evaluating the photocatalytic degradation performance of the supernatant, wherein the method for calculating the degradation rate of the rhodamine B is to divide the absorbance value A of the rhodamine B by the absorbance value A of the original rhodamine B at a specific time0. As shown in FIG. 7, the ultraviolet-visible absorption spectrogram of rhodamine B at different time. The degradation rate of the rhodamine B irradiated by visible light for 10min by using the composite material as a catalyst is 39.7 percent, and the degradation rate of the rhodamine B irradiated by visible light for 30min is 96.4 percent.
Example 2
1. And (2) placing melamine in a tubular furnace, calcining at 550 ℃ for 4h to obtain blocky graphite phase nitrogen carbide, cooling, grinding into powder, paving into a thin layer in a crucible, placing the layer into a muffle furnace, and continuously calcining at 530 ℃ for 2h to obtain lamellar graphite phase nitrogen carbide. 10mg of the lamellar graphite-phase nitrogen carbide obtained above was dispersed in 2mL of ultrapure water, and the dispersion was made uniform by ultrasonic treatment for 60 min.
2. Dissolving ammonium molybdate powder in ultrapure water, performing ultrasonic treatment to completely dissolve the ammonium molybdate powder to obtain a clear and transparent solution, adding ferric nitrate nonahydrate solid into the solution, continuing ultrasonic treatment until the ferric nitrate is completely dissolved, and standing for the solution to be solidified into a gel state. Wherein the mass ratio of ammonium molybdate powder to ferric nitrate nonahydrate solid is 1: 1.
3. Freeze drying the gel to obtain yellow green block solid, and grinding.
4. Then 2mg of the yellowish green solid powder was dissolved in 1mL of water and completely dissolved by sonication to give an orange-red clear and transparent solution.
5. Mixing graphite phase nitrogen carbide water solution and orange-red clear transparent solution, and performing ultrasonic treatment for 30min to mix them uniformly. Then transferred to the autoclave and added to increase the volume of the solution to 10mL, shaken up. Heating in a heater at 160 deg.C for 6 h. After the reaction is finished, removing the upper-layer aqueous solution by using a liquid-moving gun, and then washing the lower-layer solid product for multiple times by using ultrapure water, namely the visible light photocatalytic composite material. Finally, 5mL of ultrapure water was added and stored for further use.
And (3) performance testing: adding 150 mu L of the composite material with the iron-molybdenum oxide mass fraction of 20% obtained in the embodiment into 20mL of rhodamine B aqueous solution (the final concentration of rhodamine B is 5ppm), then adding 40 mu L of hydrogen peroxide solution (the final concentration of hydrogen peroxide is 20mmol/L), and standing at room temperature for 30min to make the composite material achieve balance on rhodamine B adsorption; then irradiated (lamp-to-sample distance 20cm) with a 300W xenon lamp source (λ max >400nm) under magnetic stirring and the timing started. Sampling at certain intervals, centrifuging, taking supernatant, measuring the absorbance of the supernatant at the maximum absorption wavelength of rhodamine B by using an ultraviolet-visible spectrophotometer, and evaluating the photocatalytic degradation performance of the supernatant. The degradation rate of the rhodamine B irradiated by visible light for 10min by using the composite material as a catalyst is 43.5 percent, and the degradation rate in 30min is 97.2 percent.
Example 3
1. And (2) placing melamine in a tubular furnace, calcining at 550 ℃ for 4h to obtain blocky graphite phase nitrogen carbide, cooling, grinding into powder, paving into a thin layer in a crucible, placing the layer into a muffle furnace, and continuously calcining at 530 ℃ for 2h to obtain lamellar graphite phase nitrogen carbide. 10mg of the lamellar graphite-phase nitrogen carbide obtained above was dispersed in 2mL of ultrapure water, and the dispersion was made uniform by ultrasonic treatment for 60 min.
2. Dissolving ammonium molybdate powder in ultrapure water, performing ultrasonic treatment to completely dissolve the ammonium molybdate powder to obtain a clear and transparent solution, adding ferric nitrate nonahydrate solid into the solution, continuing ultrasonic treatment until the ferric nitrate is completely dissolved, and standing for the solution to be solidified into a gel state. Wherein the mass ratio of ammonium molybdate powder to ferric nitrate nonahydrate solid is 1: 1.
3. Freeze drying the gel to obtain yellow green block solid, and grinding.
4. Then 3mg of the yellowish green solid powder was dissolved in 1mL of water and completely dissolved by sonication to give an orange-red clear and transparent solution.
5. Mixing graphite phase nitrogen carbide water solution and orange-red clear transparent solution, and performing ultrasonic treatment for 30min to mix them uniformly. Then transferred to the autoclave and added to increase the volume of the solution to 10mL, shaken up. Heating in a heater at 160 deg.C for 6 h. After the reaction is finished, removing the upper-layer aqueous solution by using a liquid-moving gun, and then washing the lower-layer solid product for multiple times by using ultrapure water, namely the visible light photocatalytic composite material. Finally, 5mL of ultrapure water was added and stored for further use.
And (3) performance testing: 150 mul of the composite material with the iron-molybdenum oxide mass fraction of 30% obtained in the embodiment is added into 20mL of rhodamine B aqueous solution (the final concentration of rhodamine B is 5ppm), and then 40 mul of hydrogen peroxide solution (the final concentration of hydrogen peroxide is 20mmol/L and is marked as FMO/C)3N4+20mM H2O2) Standing at room temperature for 30min to balance the adsorption of the composite material on rhodamine B; then a 300W xenon lamp light source (lambda max) is used under magnetic stirring>400nm) was illuminated (lamp 20cm from sample) and a timer was started. Sampling at certain intervals, centrifuging, taking supernatant, measuring the absorbance of the supernatant at the maximum absorption wavelength of rhodamine B by using an ultraviolet-visible spectrophotometer, and evaluating the photocatalytic degradation performance of the supernatant. The degradation rate of the rhodamine B irradiated by visible light for 10min by using the composite material as a catalyst is 54.9 percent, and the degradation rate in 30min is 98.7 percent.
Example 4
1. And (2) placing melamine in a tubular furnace, calcining at 550 ℃ for 4h to obtain blocky graphite phase nitrogen carbide, cooling, grinding into powder, paving into a thin layer in a crucible, placing the layer into a muffle furnace, and continuously calcining at 530 ℃ for 2h to obtain lamellar graphite phase nitrogen carbide. 10mg of the lamellar graphite-phase nitrogen carbide obtained above was dispersed in 2mL of ultrapure water, and the dispersion was made uniform by ultrasonic treatment for 60 min.
2. Dissolving ammonium molybdate powder in ultrapure water, performing ultrasonic treatment to completely dissolve the ammonium molybdate powder to obtain a clear and transparent solution, adding ferric nitrate nonahydrate solid into the solution, continuing ultrasonic treatment until the ferric nitrate is completely dissolved, and standing for the solution to be solidified into a gel state. Wherein the mass ratio of ammonium molybdate powder to ferric nitrate nonahydrate solid is 1: 1.
3. Freeze drying the gel to obtain yellow green block solid, and grinding.
4. 4mg of the yellowish green solid powder was then dissolved in 1mL of water and sonicated to dissolve completely to give an orange-red clear and transparent solution.
5. Mixing graphite phase nitrogen carbide water solution and orange-red clear transparent solution, and performing ultrasonic treatment for 30min to mix them uniformly. Then transferred to the autoclave and added to increase the volume of the solution to 10mL, shaken up. Heating in a heater at 160 deg.C for 6 h. After the reaction is finished, removing the upper-layer aqueous solution by using a liquid-moving gun, and then washing the lower-layer solid product for multiple times by using ultrapure water, namely the visible light photocatalytic composite material. Finally, 5mL of ultrapure water was added and stored for further use.
And (3) performance testing: adding 150 mu L of the composite material with the iron-molybdenum oxide mass fraction of 40% obtained in the embodiment into 20mL of rhodamine B aqueous solution (the final concentration of rhodamine B is 5ppm), then adding 40 mu L of hydrogen peroxide solution (the final concentration of hydrogen peroxide is 20mmol/L), and standing at room temperature for 30min to make the composite material achieve balance on rhodamine B adsorption; then irradiated (lamp-to-sample distance 20cm) with a 300W xenon lamp source (λ max >400nm) under magnetic stirring and the timing started. Sampling at certain intervals, centrifuging, taking supernatant, measuring the absorbance of the supernatant at the maximum absorption wavelength of rhodamine B by using an ultraviolet-visible spectrophotometer, and evaluating the photocatalytic degradation performance of the supernatant. The degradation rate of the rhodamine B irradiated by visible light for 10min by using the composite material as a catalyst is 42.9 percent, and the degradation rate in 30min is 96.8 percent.
Example 5
1. And (2) placing melamine in a tubular furnace, calcining at 550 ℃ for 4h to obtain blocky graphite phase nitrogen carbide, cooling, grinding into powder, paving into a thin layer in a crucible, placing the layer into a muffle furnace, and continuously calcining at 530 ℃ for 2h to obtain lamellar graphite phase nitrogen carbide. 10mg of the lamellar graphite-phase nitrogen carbide obtained above was dispersed in 2mL of ultrapure water, and the dispersion was made uniform by ultrasonic treatment for 60 min.
2. Dissolving ammonium molybdate powder in ultrapure water, performing ultrasonic treatment to completely dissolve the ammonium molybdate powder to obtain a clear and transparent solution, adding ferric nitrate nonahydrate solid into the solution, continuing ultrasonic treatment until the ferric nitrate is completely dissolved, and standing for the solution to be solidified into a gel state. Wherein the mass ratio of ammonium molybdate powder to ferric nitrate nonahydrate solid is 1: 1.
3. Freeze drying the gel to obtain yellow green block solid, and grinding.
4. Then 3mg of the yellowish green solid powder was dissolved in 1mL of water and completely dissolved by sonication to give an orange-red clear and transparent solution.
5. Mixing graphite phase nitrogen carbide water solution and orange-red clear transparent solution, and performing ultrasonic treatment for 30min to mix them uniformly. Then transferred to the autoclave and added to increase the volume of the solution to 10mL, shaken up. Heating in a heater at 160 deg.C for 6 h. After the reaction is finished, removing the upper-layer aqueous solution by using a liquid-moving gun, and then washing the lower-layer solid product for multiple times by using ultrapure water, namely the visible light photocatalytic composite material. Finally, 5mL of ultrapure water was added and stored for further use.
And (3) performance testing: adding 150 mu L of the composite material obtained in the embodiment into 20mL of rhodamine B aqueous solution (the final concentration of rhodamine B is 5ppm), then adding 20 mu L of hydrogen peroxide solution (the final concentration of hydrogen peroxide is 10mmol/L), and standing at room temperature for 30min to make the adsorption of the composite material on rhodamine B reach equilibrium; then irradiated (lamp-to-sample distance 20cm) with a 300W xenon lamp source (λ max >400nm) under magnetic stirring and the timing started. Sampling at certain intervals, centrifuging, taking supernatant, measuring the absorbance of the supernatant at the maximum absorption wavelength of rhodamine B by using an ultraviolet-visible spectrophotometer, and evaluating the photocatalytic degradation performance of the supernatant. The degradation rate of the rhodamine B irradiated by visible light for 30min by using the composite material as a catalyst is 91.7 percent, and the degradation rate in 60min is 97.6 percent.
Example 6
1. And (2) placing melamine in a tubular furnace, calcining at 550 ℃ for 4h to obtain blocky graphite phase nitrogen carbide, cooling, grinding into powder, paving into a thin layer in a crucible, placing the layer into a muffle furnace, and continuously calcining at 530 ℃ for 2h to obtain lamellar graphite phase nitrogen carbide. 10mg of the lamellar graphite-phase nitrogen carbide obtained above was dispersed in 2mL of ultrapure water, and the dispersion was made uniform by ultrasonic treatment for 60 min.
2. Dissolving ammonium molybdate powder in ultrapure water, performing ultrasonic treatment to completely dissolve the ammonium molybdate powder to obtain a clear and transparent solution, adding ferric nitrate nonahydrate solid into the solution, continuing ultrasonic treatment until the ferric nitrate is completely dissolved, and standing for the solution to be solidified into a gel state. Wherein the mass ratio of ammonium molybdate powder to ferric nitrate nonahydrate solid is 1: 1.
3. Freeze drying the gel to obtain yellow green block solid, and grinding.
4. Then 3mg of the yellowish green solid powder was dissolved in 1mL of water and completely dissolved by sonication to give an orange-red clear and transparent solution.
5. Mixing graphite phase nitrogen carbide water solution and orange-red clear transparent solution, and performing ultrasonic treatment for 30min to mix them uniformly. Then transferred to the autoclave and added to increase the volume of the solution to 10mL, shaken up. Heating in a heater at 160 deg.C for 6 h. After the reaction is finished, removing the upper-layer aqueous solution by using a liquid-moving gun, and then washing the lower-layer solid product for multiple times by using ultrapure water, namely the visible light photocatalytic composite material. Finally, 5mL of ultrapure water was added and stored for further use.
And (3) performance testing: adding 150 mu L of the composite material obtained in the embodiment into 20mL of rhodamine B aqueous solution (the final concentration of rhodamine B is 5ppm), then adding 10 mu L of hydrogen peroxide solution (the final concentration of hydrogen peroxide is 5mmol/L), and standing at room temperature for 30min to make the adsorption of the composite material on rhodamine B reach equilibrium; then irradiated (lamp-to-sample distance 20cm) with a 300W xenon lamp source (λ max >400nm) under magnetic stirring and the timing started. Sampling at certain intervals, centrifuging, taking supernatant, measuring the absorbance of the supernatant at the maximum absorption wavelength of rhodamine B by using an ultraviolet-visible spectrophotometer, and evaluating the photocatalytic degradation performance of the supernatant. The degradation rate of the rhodamine B irradiated by visible light for 30min by using the composite material as a catalyst is 60.4 percent, and the degradation rate of the rhodamine B irradiated by visible light for 90min is 96.5 percent.
Example 7
1. And (2) placing melamine in a tubular furnace, calcining at 550 ℃ for 4h to obtain blocky graphite phase nitrogen carbide, cooling, grinding into powder, paving into a thin layer in a crucible, placing the layer into a muffle furnace, and continuously calcining at 530 ℃ for 2h to obtain lamellar graphite phase nitrogen carbide. 10mg of the lamellar graphite-phase nitrogen carbide obtained above was dispersed in 2mL of ultrapure water, and the dispersion was made uniform by ultrasonic treatment for 60 min.
2. Dissolving ammonium molybdate powder in ultrapure water, performing ultrasonic treatment to completely dissolve the ammonium molybdate powder to obtain a clear and transparent solution, adding ferric nitrate nonahydrate solid into the solution, continuing ultrasonic treatment until the ferric nitrate is completely dissolved, and standing for the solution to be solidified into a gel state. Wherein the mass ratio of ammonium molybdate powder to ferric nitrate nonahydrate solid is 1: 1.
3. Freeze drying the gel to obtain yellow green block solid, and grinding.
4. Then 3mg of the yellowish green solid powder was dissolved in 1mL of water and completely dissolved by sonication to give an orange-red clear and transparent solution.
5. Mixing graphite phase nitrogen carbide water solution and orange-red clear transparent solution, and performing ultrasonic treatment for 30min to mix them uniformly. Then transferred to the autoclave and added to increase the volume of the solution to 10mL, shaken up. Heating in a heater at 160 deg.C for 6 h. After the reaction is finished, removing the upper-layer aqueous solution by using a liquid-moving gun, and then washing the lower-layer solid product for multiple times by using ultrapure water, namely the visible light photocatalytic composite material. Finally, 5mL of ultrapure water was added and stored for further use.
And (3) performance testing:
adding 150 mu L of the composite material obtained in the embodiment into 20mL of rhodamine B aqueous solution (the final concentration of rhodamine B is 5ppm), then adding 4 mu L of hydrogen peroxide solution (the final concentration of hydrogen peroxide is 2mmol/L), and standing at room temperature for 30min to make the adsorption of the composite material on rhodamine B reach equilibrium; then irradiated (lamp-to-sample distance 20cm) with a 300W xenon lamp source (λ max >400nm) under magnetic stirring and the timing started. Sampling at certain intervals, centrifuging, taking supernatant, measuring the absorbance of the supernatant at the maximum absorption wavelength of rhodamine B by using an ultraviolet-visible spectrophotometer, and evaluating the photocatalytic degradation performance of the supernatant. The degradation rate of the rhodamine B irradiated by visible light for 30min by using the composite material as a catalyst is 52.7 percent, and the degradation rate of 90min is 98.2 percent.
Example 8
1. And (2) placing melamine in a tubular furnace, calcining at 550 ℃ for 4h to obtain blocky graphite phase nitrogen carbide, cooling, grinding into powder, paving into a thin layer in a crucible, placing the layer into a muffle furnace, and continuously calcining at 530 ℃ for 2h to obtain lamellar graphite phase nitrogen carbide. 10mg of the lamellar graphite-phase nitrogen carbide obtained above was dispersed in 2mL of ultrapure water, and the dispersion was made uniform by ultrasonic treatment for 60 min.
2. Dissolving ammonium molybdate powder in ultrapure water, performing ultrasonic treatment to completely dissolve the ammonium molybdate powder to obtain a clear and transparent solution, adding ferric nitrate nonahydrate solid into the solution, continuing ultrasonic treatment until the ferric nitrate is completely dissolved, and standing for the solution to be solidified into a gel state. Wherein the mass ratio of ammonium molybdate powder to ferric nitrate nonahydrate solid is 1: 1.
3. Freeze drying the gel to obtain yellow green block solid, and grinding.
4. Then 3mg of the yellowish green solid powder was dissolved in 1mL of water and completely dissolved by sonication to give an orange-red clear and transparent solution.
5. Mixing graphite phase nitrogen carbide water solution and orange-red clear transparent solution, and performing ultrasonic treatment for 30min to mix them uniformly. Then transferred to the autoclave and added to increase the volume of the solution to 10mL, shaken up. Heating in a heater at 160 deg.C for 6 h. After the reaction is finished, removing the upper-layer aqueous solution by using a liquid-moving gun, and then washing the lower-layer solid product for multiple times by using ultrapure water, namely the visible light photocatalytic composite material. Finally, 5mL of ultrapure water was added and stored for further use.
And (3) performance testing: 150 μ L of the composite material obtained in this example was added to 20mL of rhodamine B aqueous solution (final concentration of rhodamine B is 5ppm), and 60 μ L of hydrogen peroxide was added to make the final concentration reach 30mmol/L (final concentration of hydrogen peroxide is 30mmol/, which is denoted as FMO/C)3N4+30mM H2O2) 75 mul of the composite material obtained in the embodiment is added into 20mL of rhodamine B aqueous solution (the final concentration is 5ppm), and then hydrogen peroxide is added to enable the final concentration to reach 20mmol/L (the final concentration of the hydrogen peroxide is 20mmol/, and is recorded as 1/2 FMO/C)3N4+20mM H2O2) Standing at room temperature for 30min to balance the adsorption of the composite material on rhodamine B; then a 300W xenon lamp light source (lambda max) is used under magnetic stirring>400nm) was illuminated (lamp 20cm from sample) and a timer was started. Sampling at certain intervals, centrifuging, taking supernatant, measuring the absorbance of the supernatant at the maximum absorption wavelength of rhodamine B by using an ultraviolet-visible spectrophotometer, and evaluating the photocatalytic degradation performance of the supernatant. The results are shown in FIG. 8, wherein the open circle markers are the degradation curves of the composite material after adding 20mmol/L hydrogen peroxide for photo-Fenton catalytic degradation of rhodamine B along with time. The hollow square mark is a degradation curve of the composite material which is subjected to photo-Fenton catalytic degradation of rhodamine B after 30mmol/L of hydrogen peroxide is added and changes along with time. The results show that 20mmol/L hydrogen peroxide has reached the maximum amount required for the Fenton reaction and that when added further, does not have a significant effect on the degradation efficiency. The hollow triangle mark is a degradation efficiency curve of 6.25 mu g/mL composite catalyst for photocatalytic degradation of rhodamine B.
Wherein, the composite material is used as a catalyst, hydrogen peroxide solution with final concentration of 30m mol/L is added, the degradation rate of rhodamine B in visible light irradiation for 10min is 59.7%, and the degradation rate in 30min is 98.6%. The degradation rate of the rhodamine B irradiated by visible light for 30min by using the composite material of 6.25 mu g/mL as a catalyst is 81.7 percent, and the degradation rate in 60min is 96.8 percent.
The results show that as the catalyst concentration increases, the degradation efficiency also increases.
Comparative example 1
The melamine is placed in a tube furnace, the calcination temperature is 550 ℃, the calcination time is 4 hours, after cooling, the melamine is ground into powder, and blocky graphite phase nitrogen carbide is obtained, such as yellow powder on the left side of the figure 2. Dispersing 10mg of the blocky graphite phase carbonized nitrogen obtained in the previous step into 5mL of ultrapure water, performing ultrasonic treatment for 60min to uniformly disperse the blocky graphite phase carbonized nitrogen, and storing the blocky graphite phase carbonized nitrogen for later use.
And (3) performance testing:
adding 125 mu L of the blocky graphite phase nitrogen carbide obtained in the comparative example into 20mL of rhodamine B aqueous solution (the final concentration of rhodamine B is 5ppm), and standing at room temperature for 30min to ensure that the adsorption of the composite material on the rhodamine B reaches balance; then irradiated (lamp-to-sample distance 20cm) with a 300W xenon lamp source (λ max >400nm) under magnetic stirring and the timing started. Sampling at certain intervals, centrifuging, taking supernatant, measuring the absorbance of the supernatant at the maximum absorption wavelength of rhodamine B by using an ultraviolet-visible spectrophotometer, and evaluating the photocatalytic degradation performance of the supernatant. The result is shown in fig. 9, in which the solid star mark is a degradation curve of pure massive graphite phase nitrogen carbide catalytic degradation rhodamine B.
The degradation rate of the rhodamine B irradiated by visible light for 30min by using the blocky graphite-phase nitrogen carbide as a catalyst is 11.3 percent, and the degradation rate of the rhodamine B irradiated by the visible light for 90min is 27.7 percent.
Comparative example 2
And (2) putting melamine into a tube furnace, calcining at 550 ℃ for 4h to obtain blocky graphite phase nitrogen carbide, cooling, grinding into powder, paving into a thin layer in a crucible, putting into a muffle furnace for continuous calcination at 530 ℃ for 2h to obtain lamellar graphite phase nitrogen carbide, such as pale yellow powder on the right side of the figure 2. 10mg of the lamellar graphite-phase nitrogen carbide obtained above was dispersed in 5mL of ultrapure water, and the dispersion was made uniform by ultrasonic treatment for 60 min.
And (3) performance testing:
adding 125 mu L of lamellar graphite-phase carbonized nitrogen obtained in the comparative example into 20mL of rhodamine B aqueous solution (the final concentration of rhodamine B is 5ppm), and standing at room temperature for 30min to ensure that the adsorption of the composite material on rhodamine B reaches balance; then irradiated (lamp-to-sample distance 20cm) with a 300W xenon lamp source (λ max >400nm) under magnetic stirring and the timing started. Sampling at certain intervals, centrifuging, taking supernatant, measuring the absorbance of the supernatant at the maximum absorption wavelength of rhodamine B by using an ultraviolet-visible spectrophotometer, and evaluating the photocatalytic degradation performance of the supernatant. The result is shown in fig. 9, in which the solid triangle mark is a degradation curve of pure lamellar graphite-phase nitrogen carbide catalyzed degradation of rhodamine B. The degradation rate of the rhodamine B irradiated by visible light for 30min by using lamellar graphite phase nitrogen carbide as a catalyst is 20.0%, and the degradation rate of the rhodamine B irradiated by visible light for 90min is 55.1%.
Comparative example 3
And (3) performance testing: adding 150 mu L of the composite material obtained in the embodiment 3 into 20mL of rhodamine B aqueous solution (the final concentration of rhodamine B is 5ppm), and standing at room temperature for 30min to ensure that the composite material is balanced in rhodamine B adsorption; then irradiated (lamp-to-sample distance 20cm) with a 300W xenon lamp source (λ max >400nm) under magnetic stirring and the timing started. Sampling at certain intervals, centrifuging, taking supernatant, measuring the absorbance of the supernatant at the maximum absorption wavelength of rhodamine B by using an ultraviolet-visible spectrophotometer, and evaluating the photocatalytic degradation performance of the supernatant. As shown in fig. 9, the solid square mark is a degradation curve of lamellar graphite-phase nitrogen carbide loaded with iron-molybdenum oxide for catalytic degradation of rhodamine B without hydrogen peroxide, the degradation rate of the rhodamine B irradiated by visible light for 30min by using the composite material as a catalyst is 50.9%, the degradation rate of the rhodamine B irradiated by visible light is 99.7%, and the catalytic efficiency of the composite catalytic material is far higher than that of pure massive graphite-phase nitrogen carbide and lamellar graphite-phase nitrogen carbide, which indicates that the heterojunction structure formed by the method greatly promotes catalytic degradation. However, the catalytic efficiency continued to increase when hydrogen peroxide was added, indicating that hydrogen peroxide can contribute to the enhancement of the catalytic degradation efficiency of iron molybdenum oxide-supported lamellar graphite-phase nitrogen carbide.
Comparative example 4
1. Dissolving 0.5mmol of ammonium molybdate powder in 100mL of ultrapure water, performing ultrasonic treatment to completely dissolve the ammonium molybdate powder to obtain a clear and transparent solution, then adding 0.5mmol of ferric nitrate nonahydrate solid into the solution, performing continuous ultrasonic treatment until the ferric nitrate is completely dissolved, adding 12.5g of melamine before the ferric nitrate is formed into gel, and stirring for 2 hours to form a uniform light red emulsion.
2. Freeze-drying the suspension to obtain light red block solid, and grinding into powder.
3. And (3) putting the obtained powder into a tube furnace, calcining at 550 ℃ for 4h to obtain black metal oxide at the upper layer and light yellow graphite-phase nitrogen carbide solid at the lower layer, cooling, grinding into powder, and taking a picture.
Comparative example 5
1. Dissolving 1mmol of ammonium molybdate powder in 100mL of ultrapure water, performing ultrasonic treatment to completely dissolve the ammonium molybdate powder to obtain a clear and transparent solution, adding 1mmol of ferric nitrate nonahydrate solid into the solution, performing ultrasonic treatment continuously until the ferric nitrate is completely dissolved, adding 12.5g of melamine before the ferric nitrate is formed into gel, and stirring for 2 hours to form a uniform light red emulsion.
2. Freeze-drying the suspension to obtain light red block solid, and grinding into powder.
3. And (3) putting the obtained powder into a tube furnace, calcining at 550 ℃ for 4h to obtain black metal oxide at the upper layer and light yellow graphite-phase nitrogen carbide solid at the lower layer, cooling, grinding into powder, and taking a picture.
FIG. 10 is a photograph showing the powders obtained after lyophilization in comparative example 4 (left panel) and comparative example 5 (right panel).
FIG. 11 is a photograph of the composite obtained by direct calcination in comparative example 4 (left side of the figure) and comparative example 5 (right side of the figure). It can be seen from the photographs that the metal oxide and graphite phase nitrogen carbide are layered and thus no heterojunction structure is formed.
Fig. 12 is a photograph of the composites after calcination and grinding to powders of comparative example 4 (left panel) and comparative example 5 (right panel). It can be seen from the photographs that the milled composite appears dark black and black, and the material of this color is not conducive to light energy to produce photoelectrons and is not suitable for photocatalytic degradation of wastewater.
The results of the catalytic performance of the catalysts obtained during the preparation of the large number of experiments are only listed in the above examples. From the above, the preparation method provided by the invention is simple and easy to operate and low in cost, the obtained visible-light-driven photocatalyst can effectively degrade the dye rhodamine B in the wastewater, the content of the required catalyst is low, the degradation time is short, the degradation efficiency is high, and the substantial problem of preventing and treating the pollution problem of the wastewater is solved.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in other forms, and any person skilled in the art can change or modify the technical content disclosed above into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.
Claims (7)
1. A preparation method of a visible light catalyst for degrading dyes in wastewater is characterized in that the visible light catalyst takes lamellar graphite-phase nitrogen carbide as a main body, iron-molybdenum oxide is loaded on the main body, and the iron-molybdenum oxide and the graphite-phase nitrogen carbide form a heterojunction structure, wherein the mass fraction of the iron-molybdenum oxide is 10% -40% of the mass of the graphite-phase nitrogen carbide, and the preparation method comprises the following steps:
s1, dispersing lamellar graphite phase nitrogen carbide in ultrapure water, and performing ultrasonic treatment to uniformly disperse the lamellar graphite phase nitrogen carbide;
s2, dissolving ammonium molybdate powder in ultrapure water, performing ultrasonic treatment to completely dissolve the ammonium molybdate powder to obtain a clear and transparent solution, putting ferric nitrate nonahydrate solid into the solution, continuing ultrasonic treatment until ferric nitrate is completely dissolved, and standing for the solution to be solidified into a gel state;
s3, freeze-drying the gel obtained in the step S2 to obtain a yellow-green block solid, and grinding to obtain yellow-green powder A;
s4, dissolving the powder A in ultrapure water, and performing ultrasonic treatment to obtain an orange-red transparent solution;
s5, adding the lamellar graphite-phase nitrogen carbide solution obtained in the step S1 into the orange-red transparent solution obtained in the step S4, adding ultrapure water to enable the solute concentration to reach 0.5-1 g/L, and performing ultrasonic treatment to obtain uniformly dispersed suspension; and carrying out hydrothermal reaction on the suspension to obtain the photocatalytic composite material.
2. The method according to claim 1, wherein in step S1, the lamellar graphite phase nitrogen carbide is prepared by: the method comprises the steps of carrying out primary calcination on melamine at the temperature of 500-600 ℃ for 3-5 hours to obtain blocky graphite phase nitrogen carbide, cooling, grinding into powder, and continuing secondary calcination at the temperature of 500-550 ℃ for 1.5-3 hours to obtain lamellar graphite phase nitrogen carbide.
3. The method according to claim 1, wherein in step S2, the ammonium molybdate powder and ferric nitrate nonahydrate are added in a mass ratio of 2:1 to 1: 2; dissolving in ultrapure water to make the concentration of ammonium molybdate solute reach 0.1-0.5 mol/L.
4. The production method according to claim 1, wherein in step S4, the amount of powder a is such that the ratio of graphite-phase nitrogen carbide to powder a by mass is 10: 1-10: and 4, carrying out.
5. The method according to claim 1, wherein in step S5, the hydrothermal reaction temperature is 140 to 170 ℃ and the hydrothermal time is 5 to 7 hours.
6. The method according to claim 1, wherein the hydrothermal reaction is performed at 160 ℃ for 6 hours in step S5.
7. The application of the visible-light-driven photocatalyst obtained by the preparation method of any one of claims 1 to 6 in degrading rhodamine B in wastewater is characterized by comprising the steps of adding the visible-light-driven photocatalyst and hydrogen peroxide into an aqueous solution containing rhodamine B, and stirring for 5-90 min under the irradiation of a xenon lamp light source with the wavelength of more than or equal to 400 nm;
the final concentration of the visible light catalyst in the wastewater is more than or equal to 6.25 mu g/mL, the final concentration of the hydrogen peroxide in the wastewater is 2-20 mmol/L, and the reaction time is 30-90 min.
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