CN111282580A - Silver-modified cobalt tungstate/cadmium tungstate nanofiber photocatalytic material and preparation method and application thereof - Google Patents
Silver-modified cobalt tungstate/cadmium tungstate nanofiber photocatalytic material and preparation method and application thereof Download PDFInfo
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- CN111282580A CN111282580A CN202010208010.XA CN202010208010A CN111282580A CN 111282580 A CN111282580 A CN 111282580A CN 202010208010 A CN202010208010 A CN 202010208010A CN 111282580 A CN111282580 A CN 111282580A
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- 230000001699 photocatalysis Effects 0.000 title claims abstract description 142
- 239000000463 material Substances 0.000 title claims abstract description 131
- PBYZMCDFOULPGH-UHFFFAOYSA-N tungstate Chemical compound [O-][W]([O-])(=O)=O PBYZMCDFOULPGH-UHFFFAOYSA-N 0.000 title claims abstract description 87
- 229910052793 cadmium Inorganic materials 0.000 title claims abstract description 76
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 title claims abstract description 75
- OMAWWKIPXLIPDE-UHFFFAOYSA-N (ethyldiselanyl)ethane Chemical class CC[Se][Se]CC OMAWWKIPXLIPDE-UHFFFAOYSA-N 0.000 title claims abstract description 64
- 238000002360 preparation method Methods 0.000 title claims abstract description 33
- MYSWGUAQZAJSOK-UHFFFAOYSA-N ciprofloxacin Chemical compound C12=CC(N3CCNCC3)=C(F)C=C2C(=O)C(C(=O)O)=CN1C1CC1 MYSWGUAQZAJSOK-UHFFFAOYSA-N 0.000 claims abstract description 124
- 239000002131 composite material Substances 0.000 claims abstract description 86
- 229910052709 silver Inorganic materials 0.000 claims abstract description 71
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- 239000002243 precursor Substances 0.000 claims abstract description 68
- 229960003405 ciprofloxacin Drugs 0.000 claims abstract description 62
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 56
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 claims abstract description 36
- 238000006243 chemical reaction Methods 0.000 claims abstract description 33
- -1 silver modified cobalt tungstate Chemical class 0.000 claims abstract description 28
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- 238000006731 degradation reaction Methods 0.000 claims abstract description 25
- 238000000034 method Methods 0.000 claims abstract description 18
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- LHQLJMJLROMYRN-UHFFFAOYSA-L cadmium acetate Chemical compound [Cd+2].CC([O-])=O.CC([O-])=O LHQLJMJLROMYRN-UHFFFAOYSA-L 0.000 claims abstract description 16
- 238000013033 photocatalytic degradation reaction Methods 0.000 claims abstract description 16
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 claims abstract description 15
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- B01J35/39—
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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
- B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
- B01J23/8933—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/8993—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with chromium, molybdenum or tungsten
-
- B01J35/393—
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- B01J35/58—
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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
-
- 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
- C02F2101/38—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
- C02F2305/10—Photocatalysts
Abstract
The invention relates to a silver-modified cobalt tungstate/cadmium tungstate nanofiber photocatalytic material as well as a preparation method and application thereof. The method comprises the steps of preparing a spinnable precursor sol by using ammonium metatungstate, cadmium acetate, cobalt nitrate and polyvinylpyrrolidone as reaction raw materials, and preparing cobalt tungstate/cadmium tungstate nano-fibers through electrostatic spinning and calcination; silver nitrate is used as a reaction raw material, silver particles are deposited on the cobalt tungstate/cadmium tungstate nano-fibers through a silver mirror reaction, and thus the silver modified cobalt tungstate/cadmium tungstate composite nano-fiber photocatalytic material is formed. The silver modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material prepared by the invention realizes efficient photocatalytic degradation of ciprofloxacin under visible light, the degradation rate can reach 93.5% within 90min, the preparation method is simple in steps and low in cost, and can be recycled, so that the application cost is greatly reduced.
Description
Technical Field
The invention relates to a silver-modified cobalt tungstate/cadmium tungstate nanofiber photocatalytic material as well as a preparation method and application thereof, belonging to the technical field of photocatalytic materials.
Background
Since the 21 st century, various activities of human beings have been increasingly frequent, with the consequent enormous energy and environmental problems in addition to the vigorous development of economy and the improvement of the living standard of human beings. Among them, the problem of water pollution associated with human survival is one of the most urgent problems to be solved. In the current environmental problem remediation, semiconductor photocatalytic technology has the unique property of directly utilizing solar energy as a light source to drive redox reaction, and is gradually one of the most promising approaches for human to solve the problem of water pollution.
Since the establishment of a semiconductor titanium dioxide electrode capable of hydrolyzing water to generate oxygen and hydrogen under the irradiation of ultraviolet light in Showa and Benzao in 1972, various TiO-based electrodes have been reported2But TiO, a new visible-light-induced photocatalyst of2The practical application of the photocatalyst in the field of photocatalysis is limited by the defects of large forbidden band width, absorption of ultraviolet light in sunlight, low utilization rate of solar energy and the like. Therefore, the development of a novel visible light photocatalyst is one of the problems to be solved urgently in the practical production of the photocatalytic technology. In recent years, CoWO4,CdWO4The tungstate semiconductor has the advantages of good ultraviolet and visible light absorption, stable structure, good photocatalytic performance and the like, and is widely applied to the field of photocatalysis. For example: the inventor of the present application earlier-stage patent document CN110327914A discloses a tungsten trioxide/cadmium tungstate nanofiber photocatalytic material, a preparation method and an application thereof. Dissolving ammonium metatungstate and cadmium acetate in a mixed solvent consisting of absolute ethyl alcohol and N, N-dimethylformamide, and adding polyvinylpyrrolidone to obtain a spinnable precursor sol; by controlling spinnability of precursorsPreparing precursor fiber by the rheological property of the sol and the spinning process parameters, then calcining the precursor fiber at high temperature at different temperatures to obtain the tungsten trioxide/cadmium tungstate nanofiber photocatalytic material, and preparing the nanofiber photocatalytic material with a tube-in-tube structure by a preferred experimental scheme. The catalytic degradation rate of the photocatalytic material to tetracycline under the illumination condition can reach 93.1% in 120 min.
Studies have shown that metallic Ag plays a critical role in accelerating charge separation and enhancing photocatalytic activity, e.g., ACS Sustainable Chemistry&Engineering 4(6)2016:3017-3023, reported g-C3N4Co-modified Bi with Ag2WO6The photoreactivity of the microspheres under visible light irradiation and the mechanism thereof. However, the composite material prepared by the method is a non-one-dimensional nano material, is not beneficial to transmission and separation of photon-generated carriers, is difficult to recycle, and has high application cost.
Thus, CoWO is prepared using electrospinning4/CdWO4The heterojunction can effectively improve the photocatalytic performance, and meanwhile, a small amount of metal nanoparticles Ag are introduced to serve as additional recombination centers to generate a surface plasmon resonance effect, so that the system has more visible light response, and more effective charge transfer can be established. After the noble metal nano particles are introduced, the effective separation of photoinduced electron-hole pairs can be induced, and then the catalytic performance driven by visible light can be improved, so that strong visible light response and solar energy transmission are realized. Meanwhile, the introduction mode of the Ag nano particles is optimized, and the phenomenon that agglomeration affects the transmission of photo carriers and further affects the catalytic performance is avoided. The invention is therefore proposed.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a silver-modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material, a preparation method and application thereof, so that the efficient photocatalytic degradation of ciprofloxacin under visible light is realized, the silver-modified cobalt tungstate/cadmium tungstate nanofiber photocatalytic material can be recycled, and the production cost is greatly reduced.
Description of terms:
room temperature: the room temperature according to the invention has the meaning known in the art and is generally 20-25 ℃.
The technical scheme of the invention is as follows:
a silver modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material is characterized in that silver particles are loaded on the surface of cobalt tungstate/cadmium tungstate nanofibers in a microscopic shape.
According to the invention, the diameter of the cobalt tungstate/cadmium tungstate nano fiber is 100-400nm, the length of the cobalt tungstate/cadmium tungstate nano fiber is 5-20 mu m, and the silver particles are spherical particles with the diameter of 10-20 nm.
According to the optimization of the invention, the cobalt tungstate/cadmium tungstate nanofiber is prepared by preparing a spinnable precursor sol by taking ammonium metatungstate, cadmium acetate, cobalt nitrate and polyvinylpyrrolidone as reaction raw materials, and performing electrostatic spinning and calcination; the silver particles are formed by taking silver nitrate as a reaction raw material and depositing the silver nitrate on the cobalt tungstate/cadmium tungstate nano-fibers through a silver mirror reaction, so that the silver modified cobalt tungstate/cadmium tungstate composite nano-fiber photocatalytic material is formed.
Further preferably, the mol ratio of Cd and Co in the spinnable precursor sol is 1 (1-4).
According to the invention, the preparation method of the silver modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material comprises the following steps:
preparing a spinnable precursor sol by taking ammonium metatungstate, cadmium acetate, cobalt nitrate and polyvinylpyrrolidone as reaction raw materials, and preparing cobalt tungstate/cadmium tungstate nano fibers by electrostatic spinning and calcining; silver nitrate is used as a reaction raw material, silver particles are deposited on the cobalt tungstate/cadmium tungstate nano-fibers through a silver mirror reaction, and thus the silver modified cobalt tungstate/cadmium tungstate composite nano-fiber photocatalytic material is formed.
According to a preferred embodiment of the present invention, the spinnable precursor sol has a molar ratio of Cd to Co of 1: (1-4); further preferably, the molar ratio of Cd to Co in the spinnable precursor sol is 1: (1-3).
According to the invention, the molar ratio of the cadmium acetate to the ammonium metatungstate is 1: (0.1667-0.3333), i.e., the molar ratio of Cd to W is 1: (2-4).
According to the invention, the spinnable precursor sol preferably has a viscosity of 0.1 to 1.0 Pa.S. The polyvinylpyrrolidone has the function of adjusting the viscosity of the precursor sol to a degree suitable for spinning.
Preferably, according to the invention, the polyvinylpyrrolidone has a weight average molecular weight of 4 to 300 ten thousand; more preferably, the weight average molecular weight of the polyvinylpyrrolidone is 100 to 150 ten thousand; most preferably, the polyvinylpyrrolidone has a weight average molecular weight of 130 ten thousand, and an optimal nanofiber photocatalytic material can be obtained.
Preferably, according to the invention, the acceptance distance of the electrospinning is 10-25 cm; the spraying rate is 1.5mL/h, the voltage is 20-30kV, and the temperature is 20-25 ℃.
Preferably, according to the invention, the calcination temperature is 500-600 ℃; further preferably, the temperature is raised to 500-. Most preferably, the temperature rise in the step (3) is carried out at a rate of 2 ℃/min to 600 ℃ and is kept for 120 min. The cobalt tungstate/cadmium tungstate nano fiber photocatalysis material is prepared under the condition of temperature rise.
According to the invention, the preferable ratio of the mole number of the silver nitrate to the mass of the cobalt tungstate/cadmium tungstate nano fiber is controlled to be (1-4): 1;
further preferably, the molar number of silver nitrate and the mass ratio of cobalt tungstate/cadmium tungstate nano fibers are controlled to be 2.5: 1.
according to the invention, the water bath temperature is controlled to be 40-50 ℃, the pH is controlled to be 9-12, AgNO is preferably used in the silver mirror reaction process3The concentration is 0.01-0.04M, and the concentration of glucose solution is 0.05-0.2M;
further preferably, the temperature of the water bath is controlled to be 50 ℃, the pH value is controlled to be 10, and AgNO is adopted in the silver mirror reaction process3The concentration is 0.03M, and the concentration of glucose solution is 0.05-0.15M.
Preferably, the silver nitrate solution is precipitated by sodium hydroxide, then ammonia water is added to dissolve the precipitate, the obtained solution is a silver ammonia solution, cobalt tungstate/cadmium tungstate nano-fibers are added, and a glucose solution is dropwise added, so that the silver modified cobalt tungstate/cadmium tungstate composite nano-fiber photocatalytic material is obtained. The nano silver particles prepared by the method for reducing silver ions into nano silver by utilizing the silver mirror reaction have small diameter and uniform distribution, and the problem of quantum yield reduction caused by thermodynamic instability, uneven particle size, overlarge particle size and the like of direct light deposition is solved. Meanwhile, the cobalt tungstate/cadmium tungstate nanofiber carrier can also play a role in stabilizing silver nanoparticles and preventing cluster aggregation, the formed nano silver is uniformly distributed on the surface of the fiber by ultrasonic and high-speed uniform stirring in the experimental process, the silver particles on the surface generate strong light absorption by exciting surface plasmon polaritons, and then high-energy or hot carriers are excited and transiently transferred to drive the photocatalysis process. The appropriate silver loading ratio (2.5:1) is optimized and the reaction conditions (water bath temperature, pH and solution concentration) are controlled to maintain the nano-scale size (about 15nm) so as to be beneficial to the effective scattering of resonance photons by the silver nanoparticles and prolong the optical path of photons, thereby increasing the formation rate of current carriers in a semiconductor, but the excessive silver can become an electron hole recombination center, cover partial active sites of the catalyst, block the electron transfer and reduce the contact area of pollutants and the photocatalyst, so that the photocatalytic activity is reduced; meanwhile, excessive nano silver particles are easy to fall off from the surface of the fiber, and are agglomerated due to high surface energy, so that the recycling of the material is not facilitated.
According to the invention, a preferred embodiment of the preparation method of the silver-modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material comprises the following steps:
(1) preparation of spinnable precursor sol
Dissolving ammonium metatungstate, cadmium acetate and cobalt nitrate in a mixed solvent consisting of methanol and N, N-dimethylformamide, adding polyvinylpyrrolidone (PVP) until the viscosity is 0.1-1.0 Pa.S, and uniformly stirring to obtain a spinnable precursor sol;
(2) preparation of cobalt tungstate/cadmium tungstate precursor fiber
Performing electrostatic spinning on the spinnable precursor sol obtained in the step (1) under the conditions that the temperature is 15-35 ℃, the voltage is 10-30kV, and the ejection rate is 0.1-1.5mL/h to obtain precursor fiber;
(3) preparation of cobalt tungstate/cadmium tungstate nano fiber photocatalysis material
And (3) drying the precursor fiber prepared in the step (2) at the temperature of 40-100 ℃ for 12-36h, heating to 400-600 ℃ at the speed of 1-5 ℃/min, and preserving the heat for 60-180min to obtain the cobalt tungstate/cadmium tungstate nanofiber photocatalytic material.
(4) Preparation of silver modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material
13 drops of 0.1-0.3M NaOH are added to 10ml of 0.03M AgNO3Stirring the solution continuously until a brown precipitate appears, and then continuing to add NH3·H2O until the precipitate is dissolved, then 0.02g of the nanofiber prepared in step (3) is added to the solution, and finally 5 drops of 0.05-0.2M glucose solution are added dropwise to the solution and stirring is continued for one minute. And washing and drying to obtain the silver modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material.
According to the present invention, preferably, the volume ratio of methanol to N, N-dimethylformamide in the mixed solvent in step (1) is 1: (1-4); further preferably, the volume ratio of methanol to N, N-dimethylformamide in the mixed solvent is 1: (1.5-3).
According to the invention, the drying condition in the step (3) is preferably 40-60 ℃ for 12-24 h.
According to the invention, the silver modified cadmium tungstate/cobalt tungstate composite nanofiber photocatalytic material is applied to the photocatalytic oxidation degradation of ciprofloxacin.
According to the method for degrading ciprofloxacin by photocatalysis, the silver modified cadmium tungstate/cobalt tungstate composite nanofiber is used as a photocatalysis material.
The method for degrading ciprofloxacin by photocatalysis comprises the following steps:
adding silver modified cadmium tungstate/cobalt tungstate composite nano-fibers as a photocatalytic material into a ciprofloxacin-containing solution, and degrading under the illumination condition; preferably, the photocatalytic degradation is carried out under light conditions while stirring.
According to the present invention, the concentration of ciprofloxacin in the ciprofloxacin-containing solution is 20 to 30 mg/L. Under the concentration range, the photocatalytic degradation efficiency of ciprofloxacin is optimal. Preferably, 0.5-0.8g of silver modified cadmium tungstate/cobalt tungstate composite nano-fiber is added into each liter of solution containing ciprofloxacin as a photocatalytic material.
Dissolving ammonium metatungstate, cadmium acetate and cobalt nitrate in a mixed solvent consisting of methanol and N, N-dimethylformamide, and adding polyvinylpyrrolidone to obtain a spinnable precursor sol; preparing precursor fiber by controlling rheological property and spinning technological parameters of spinnable precursor sol, and then calcining the precursor fiber at high temperature at different temperatures to obtain the cadmium tungstate/cobalt tungstate nanofiber photocatalytic material. The silver-modified cadmium tungstate/cobalt tungstate composite nanofiber photocatalytic material is successfully prepared by loading Ag nanoparticles through silver mirror reaction. The nano silver particles prepared by the method for reducing silver ions into nano silver by utilizing the silver mirror reaction have small diameter and uniform distribution, and the problem of quantum yield reduction caused by thermodynamic instability, uneven particle size, overlarge particle size and the like of direct light deposition is solved. Meanwhile, the cobalt tungstate/cadmium tungstate nanofiber carrier can also play a role in stabilizing silver nanoparticles and preventing cluster aggregation, the formed nano silver is uniformly distributed on the surface of the fiber by ultrasonic and high-speed uniform stirring in the experimental process, the silver particles on the surface generate strong light absorption by exciting surface plasmon polaritons, and then high-energy or hot carriers are excited and transiently transferred to drive the photocatalysis process.
The silver modified cadmium tungstate/cobalt tungstate composite nanofiber photocatalytic material prepared by the invention realizes efficient photocatalytic degradation of ciprofloxacin under visible light, can be recycled, and further reduces the cost.
The invention has the following beneficial effects:
1. for photocatalytic materials, the micro-morphology is one of the key factors affecting their photocatalytic performance. The one-dimensional silver modified cadmium tungstate/cobalt tungstate composite fiber photocatalytic material is beneficial to transmission and separation of photo-generated carriers, so that more photo-generated electrons and holes are ensured to participate in an oxidation-reduction reaction, the photocatalytic efficiency is greatly improved, ciprofloxacin is degraded in a photocatalytic manner under the irradiation of visible light, and the degradation rate can reach 93.5% within 90 min.
2. The prepared silver-modified cadmium tungstate/cobalt tungstate composite cadmium nanofiber photocatalytic material is relatively uniform in fiber diameter and particle size, and overcomes the defect of easy agglomeration of a hydrothermal method; CdWO4In CoWO4After the composite, the material can absorb more visible light, and the Ag nano particles are loaded to generate a surface plasma resonance effect, so that the photocatalytic efficiency is further improved.
3. The invention loads silver particles on the surface of the cadmium tungstate/cobalt tungstate composite cadmium nanofiber through silver mirror reaction, and the nano silver particles prepared by the method for reducing silver ions into nano silver by utilizing the silver mirror reaction have smaller diameter and uniform distribution, thereby avoiding the problem of quantum yield reduction caused by thermodynamic instability, uneven particle size, overlarge particle size and the like of direct light deposition. Meanwhile, the cobalt tungstate/cadmium tungstate nanofiber carrier can also play a role in stabilizing silver nanoparticles and preventing cluster aggregation, the formed nano silver is uniformly distributed on the surface of the fiber by ultrasonic and high-speed uniform stirring in the experimental process, the silver particles on the surface generate strong light absorption by exciting surface plasmon polaritons, and then high-energy or hot carriers are excited and transiently transferred to drive the photocatalysis process.
4. The preparation method has simple steps, easy operation and low cost; and the material with the one-dimensional linear morphology is convenient to recover by a sedimentation method, can be recycled, and further reduces the cost.
Drawings
FIG. 1 shows CoWO obtained in example 14/CdWO4Nanofibers and Ag/CoWO4/CdWO4An X-ray diffraction (XRD) spectrum of the composite nanofiber;
FIG. 2 shows CoWO obtained in example 14/CdWO4SEM images of nanofibers; in the figure, a is CoWO4/CdWO4The SEM image of the nano fiber with low magnification, and b is the SEM image with high magnification;
FIG. 3 shows CoWO obtained in example 14/CdWO4TEM images of nanofibers; in the figure, a is CoWO4/CdWO4Nano-fiberA low magnification TEM image, b is a high magnification TEM image;
FIG. 4 shows Ag/CoWO obtained in example 14/CdWO4TEM images of the composite nanofibers; in the figure, a is Ag/CoWO4/CdWO4The composite nanofiber TEM image with low magnification, and b is the TEM image with high magnification;
FIG. 5 shows Ag/CoWO obtained in example 14/CdWO4The composite nanofiber photocatalytic material can be used for photocatalytic degradation of an absorbance curve of ciprofloxacin under the irradiation of a simulated sunlight source; the curves in the graph sequentially correspond to the curves in the graph from top to bottom for 0-90 min;
FIG. 6 is a CoWO obtained in comparative example 14/CdWO4The nano-fiber photocatalytic material photocatalytically degrades the absorbance curve of ciprofloxacin under the irradiation of a simulated sunlight source; the curves in the graph sequentially correspond to the curves in the graph from top to bottom for 0-90 min;
FIG. 7 shows CoWO obtained in comparative example 24/CdWO4The powder material is used for photocatalytic degradation of an absorbance curve of ciprofloxacin under the irradiation of a simulated sunlight light source; the curves in the graph sequentially correspond to the curves in the graph from top to bottom for 0-90 min;
FIG. 8 is a graph of Ag/CoWO obtained in comparative example 34/CdWO4The composite nanofiber photocatalytic material can be used for photocatalytic degradation of an absorbance curve of ciprofloxacin under the irradiation of a simulated sunlight source; the curves in the graph sequentially correspond to the curves in the graph from top to bottom for 0-90 min;
FIG. 9 shows CoWO obtained in comparative example 14/CdWO4And Ag/CoWO obtained in example 14/CdWO4C/C of ciprofloxacin solution after catalytic reaction of composite nanofiber photocatalytic material0A graph of change with illumination time; in the figure, a is C/C of 60min dark reaction0Variation curve diagram, b is C/C under illumination condition0A variation graph;
FIG. 10 is a CoWO obtained in comparative example 24/CdWO4Powder material and Ag/CoWO prepared in comparative example 34/CdWO4C/C of ciprofloxacin solution after catalytic reaction of composite nanofiber photocatalytic material0A graph of change with illumination time;in the figure, a is C/C of 60min dark reaction0Variation curve diagram, b is C/C under illumination condition0A variation graph;
FIG. 11 shows Ag/CoWO obtained in example 14/CdWO4The composite nanofiber photocatalytic material is used for repeatedly and circularly utilizing the histogram of degradation efficiency of ciprofloxacin for four times under the irradiation of a simulated sunlight source;
FIG. 12 is a CoWO obtained in comparative example 14/CdWO4The degradation efficiency histogram of the ciprofloxacin is repeatedly recycled for four times by the nanofiber photocatalytic material under the irradiation of a simulated sunlight light source;
FIG. 13 is a CoWO obtained in comparative example 24/CdWO4The degradation efficiency histogram of the ciprofloxacin by the powder material under the irradiation of the simulated sunlight source is repeatedly recycled for four times;
FIG. 14 is a graph of Ag/CoWO obtained in comparative example 34/CdWO4The composite nanofiber photocatalytic material is used for repeatedly and circularly utilizing the histogram of degradation efficiency of ciprofloxacin for four times under the irradiation of a simulated sunlight light source.
Detailed Description
The invention will be further illustrated with reference to specific examples, without limiting the scope of the invention thereto. Meanwhile, the experimental methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials, unless otherwise indicated, are commercially available; the equipment used is conventional equipment. Wherein: the polyvinylpyrrolidone is polyvinylpyrrolidone K90, and has a weight average molecular weight of 130 ten thousand.
Example 1
Silver modified cadmium tungstate/cobalt tungstate (Ag/CoWO)4/CdWO4) The preparation method of the composite nanofiber photocatalytic material comprises the following steps:
(1) preparation of spinnable precursor sol: 0.7391g (W: 3mmol) of ammonium metatungstate, 0.2665g (Cd: 1mmol) of cadmium acetate and 0.9046g (Co: 2mmol) of cobalt nitrate are dissolved in a mixed solvent consisting of 3mL of methanol and 7mL of N, N-dimethylformamide, stirred until the cobalt nitrate is completely dissolved, 0.8g of polyvinylpyrrolidone (PVP) is added, and stirred uniformly to obtain a spinnable precursor sol with the viscosity of 0.5 Pa.S;
(2)CoWO4/CdWO4preparing precursor fiber: spraying the spinnable precursor sol into a receiving plate by using a plastic injector with a stainless steel needle, wherein the receiving distance between the stainless steel needle of the injector and the receiving plate is 15cm, the spraying speed of the spinnable precursor sol is 1.5mL/h, the voltage is 20kV, the electrostatic spinning temperature is controlled at 25 ℃, and precursor fiber is obtained;
(3)CoWO4/CdWO4preparing a nanofiber photocatalytic material: drying the precursor fiber prepared in the step (2) in a drying oven at 60 ℃ for 12h, then placing the dried precursor fiber in a high-temperature furnace, heating to 550 ℃ at the heating rate of 2 ℃/min, and preserving heat for 120min to obtain CoWO4/CdWO4A nanofiber photocatalytic material.
(4) Preparation of silver modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material
13 drops of 0.1M NaOH were added to 10ml of 0.03M AgNO3Stirring the solution continuously until a brown precipitate appears, and then continuing to add NH3·H2O until the precipitate was dissolved, then 0.02g of the nanofiber prepared in step (3) was added to the solution, and finally 5 drops of 0.05M glucose solution were added dropwise to the above solution and stirring was continued for one minute. Washing and drying to obtain the silver modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material
FIG. 1 shows CoWO prepared in this example4/CdWO4Nano-fiber photocatalytic material and Ag/CoWO4/CdWO4An X-ray diffraction (XRD) spectrum of the composite nanofiber; FIG. 2 shows CoWO prepared in this example4/CdWO4SEM images of nanofiber photocatalytic materials; FIG. 3 shows CoWO prepared in this example4/CdWO4TEM images of nanofiber photocatalytic materials; FIG. 4 shows Ag/CoWO prepared in this example4/CdWO4TEM images of composite nanofiber photocatalytic materials. As can be seen from FIG. 1, after sintering at 550 ℃ CoWO4/CdWO4Diffraction peak and monoclinic CdWO of nanofiber photocatalytic material4(JCPDS No.14-0676) and monoclinic CoWO4(JCPDS No.15-0867) corresponds well; after loading silver, a diffraction peak of Ag (JCPDS No.41-1402) can be found; as can be seen from FIG. 2, the cobalt tungstate/cadmium tungstate nanofiber photocatalytic material prepared in this example is a nanofiber with relatively uniform diameter and a length of 10-20 μm; FIG. 3 further demonstrates the morphology of the prepared cobalt tungstate/cadmium tungstate nanofiber photocatalytic material; from fig. 4, it can be known that silver particles are successfully loaded on the cobalt tungstate/cadmium tungstate nanofibers.
Example 2
Silver modified cadmium tungstate/cobalt tungstate (Ag/CoWO)4/CdWO4) The preparation method of the composite nanofiber photocatalytic material comprises the following steps:
(1) preparation of spinnable precursor sol: 0.7391g (W: 3mmol) of ammonium metatungstate, 0.2665g (Cd: 1mmol) of cadmium acetate and 0.9046g (Co: 2mmol) of cobalt nitrate are dissolved in a mixed solvent consisting of 3mL of methanol and 7mL of N, N-dimethylformamide, stirred until the cobalt nitrate is completely dissolved, 0.8g of polyvinylpyrrolidone (PVP) is added, and stirred uniformly to obtain a spinnable precursor sol with the viscosity of 0.5 Pa.S;
(2)CoWO4/CdWO4preparing precursor fiber: spraying the spinnable precursor sol into a receiving plate by using a plastic injector with a stainless steel needle, wherein the receiving distance between the stainless steel needle of the injector and the receiving plate is 25cm, the spraying speed of the spinnable precursor sol is 1.5mL/h, the voltage is 30kV, the electrostatic spinning temperature is controlled at 25 ℃, and precursor fiber is obtained;
(3)CoWO4/CdWO4preparing a nanofiber photocatalytic material: drying the precursor fiber prepared in the step (2) in a drying oven at 60 ℃ for 12h, then placing the dried precursor fiber in a high-temperature furnace, heating to 550 ℃ at the heating rate of 1 ℃/min, and preserving heat for 120min to obtain CoWO4/CdWO4A nanofiber photocatalytic material.
(4) Preparation of silver modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material
13 drops of 0.2M NaOH were added to 10ml of 0.03M AgNO3Stirring the solution continuously until a brown precipitate appears, and then continuing to add NH3·H2O until the precipitate dissolvesAnd (3) adding 0.02g of the nano-fibers prepared in the step (3) into the solution, and finally dropwise adding 5 drops of 0.1M glucose solution into the solution and continuously stirring for one minute. And washing and drying to obtain the silver modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material.
Example 3
Silver modified cadmium tungstate/cobalt tungstate (Ag/CoWO)4/CdWO4) The preparation method of the composite nanofiber photocatalytic material comprises the following steps:
(1) preparation of spinnable precursor sol: 0.6159g (W: 2.5mmol) of ammonium metatungstate, 0.2665g (Cd: 1mmol) of cadmium acetate and 0.6784 (Co: 1.5mmol) of cobalt nitrate are dissolved in a mixed solvent consisting of 3mL of absolute ethyl alcohol and 7mL of N, N-dimethylformamide, stirred until the mixture is completely dissolved, 1.2g of polyvinylpyrrolidone (PVP) is added, and stirred uniformly to obtain a spinnable precursor sol with the viscosity of 0.7 Pa.S;
(2)CoWO4/CdWO4preparing precursor fiber: spraying the spinnable precursor sol into a receiving plate by using a plastic injector with a stainless steel needle, wherein the receiving distance between the stainless steel needle of the injector and the receiving plate is 25cm, the spraying speed of the spinnable precursor sol is 1.5mL/h, the voltage is 25kV, the electrostatic spinning temperature is controlled at 25 ℃, and precursor fiber is obtained;
(3)CoWO4/CdWO4preparing a nanofiber photocatalytic material: drying the precursor fiber prepared in the step (2) in a drying oven at 40 ℃ for 24h, then placing the dried precursor fiber in a high-temperature furnace, heating to 550 ℃ at the heating rate of 1 ℃/min, and preserving heat for 120min to obtain CoWO4/CdWO4A nanofiber photocatalytic material.
(4) Preparation of silver modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material
13 drops of 0.2M NaOH were added to 10ml of 0.03M AgNO3Stirring the solution continuously until a brown precipitate appears, and then continuing to add NH3·H2O until the precipitate was dissolved, then 0.02g of the nanofiber prepared in step (3) was added to the solution, and finally 5 drops of 0.05M glucose solution were added dropwise to the above solution and stirring was continued for one minute. Washed and driedAnd drying to obtain the silver modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material.
Example 4
Silver modified cadmium tungstate/cobalt tungstate (Ag/CoWO)4/CdWO4) The preparation method of the composite nanofiber photocatalytic material comprises the following steps:
(1) preparation of spinnable precursor sol: 0.7391g (W: 4mmol) of ammonium metatungstate, 0.2665g (Cd: 1mmol) of cadmium acetate and 1.3568 (Co: 3mmol) of cobalt nitrate are dissolved in a mixed solvent consisting of 5mL of methanol and 10mL of N, N-dimethylformamide, stirred until the mixture is completely dissolved, 1.2g of polyvinylpyrrolidone (PVP) is added, and stirred uniformly to obtain a spinnable precursor sol with the viscosity of 0.8 Pa.S;
(2)CoWO4/CdWO4preparing precursor fiber: spraying the spinnable precursor sol into a receiving plate by using a plastic injector with a stainless steel needle, wherein the receiving distance between the stainless steel needle of the injector and the receiving plate is 20cm, the spraying speed of the spinnable precursor sol is 1.5mL/h, the voltage is 25kV, the electrostatic spinning temperature is controlled at 25 ℃, and precursor fiber is obtained;
(3)CoWO4/CdWO4preparing a nanofiber photocatalytic material: drying the precursor fiber prepared in the step (2) in a drying oven at 40 ℃ for 24h, then placing the dried precursor fiber in a high-temperature furnace, heating to 600 ℃ at the heating rate of 2 ℃/min, and preserving heat for 60min to obtain CoWO4/CdWO4A nanofiber photocatalytic material.
(4) Preparation of silver modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material
13 drops of 0.2M NaOH were added to 10ml of 0.03M AgNO3Stirring the solution continuously until a brown precipitate appears, and then continuing to add NH3·H2O until the precipitate dissolved, then 0.02g of the nanofibers obtained in step (3) was added to the solution, and finally 5 drops of 0.15M glucose solution were added dropwise to the above solution and stirring was continued for one minute. And washing and drying to obtain the silver modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material.
Comparative example 1
In example 1Prepared CoWO4/CdWO4The nanofiber composite was the composite of comparative example 1.
Comparative example 2
Cobalt tungstate/cadmium tungstate (CoWO)4/CdWO4) The preparation method of the nano powder composite material comprises the following steps:
(1) adding 0.8g of polyvinylpyrrolidone (PVP) into a beaker containing 3mL of methanol and 7mL of N, N-dimethylformamide, stirring until the solution is clear and transparent, adding 0.7391g (W: 3mmol) of ammonium metatungstate, 0.2665g (Cd: 1mmol) of cadmium acetate and 0.9046g (Co: 2mmol) of nitric acid, and continuously stirring for 2 hours to obtain a clear precursor sol;
(2) placing the precursor sol prepared in the step (1) in a watch glass, and placing the watch glass in a drying oven to be dried for 12 hours at the temperature of 80 ℃ to obtain a gel block material;
(3) grinding the gel block material prepared in the step (2) by using a mortar for 10-20min to obtain powder particles, and then placing the powder particles in a muffle furnace at 1 ℃ for min-1Heating to 550 deg.C, maintaining for 120min, and naturally cooling to room temperature to obtain cobalt tungstate/cadmium tungstate (CoWO)4/CdWO4) A nano-powder composite material.
Comparative example 3
Silver modified cadmium tungstate/cobalt tungstate (Ag/CoWO)4/CdWO4) The preparation method of the composite nanofiber photocatalytic material comprises the following steps:
(1) preparation of spinnable precursor sol: 0.7391g (W: 3mmol) of ammonium metatungstate, 0.2665g (Cd: 1mmol) of cadmium acetate and 0.9046g (Co: 2mmol) of cobalt nitrate are dissolved in a mixed solvent consisting of 3mL of methanol and 7mL of N, N-dimethylformamide, stirred until the cobalt nitrate is completely dissolved, 0.8g of polyvinylpyrrolidone (PVP) is added, and stirred uniformly to obtain a spinnable precursor sol with the viscosity of 0.5 Pa.S;
(2)CoWO4/CdWO4preparing precursor fiber: spraying the spinnable precursor sol into a receiving plate by using a plastic injector with a stainless steel needle, wherein the receiving distance between the stainless steel needle of the injector and the receiving plate is 15cm, the spraying speed of the spinnable precursor sol is 1.5mL/h, and the voltage is20kV, controlling the electrostatic spinning temperature at 25 ℃ to obtain precursor fiber;
(3)CoWO4/CdWO4preparing a nanofiber photocatalytic material: drying the precursor fiber prepared in the step (2) in a drying oven at 60 ℃ for 12h, then placing the dried precursor fiber in a high-temperature furnace, heating to 550 ℃ at the heating rate of 2 ℃/min, and preserving heat for 120min to obtain CoWO4/CdWO4A nanofiber photocatalytic material.
(4) Preparation of silver modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material
10ml of 0.03M AgNO3And (3) adding 0.02g of the nanofiber prepared in the step (3) into the solution, placing the solution under a 500W xenon lamp, and continuously stirring the solution for 60 min. Washing and drying to obtain the silver modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material
Application example 1
Photocatalytic degradation of ciprofloxacin
The Ag/CoWO prepared in example 14/CdWO4Composite nanofiber photocatalytic material and CoWO prepared in comparative example 14/CdWO4The nanofiber photocatalytic material is applied to photocatalytic degradation of Ciprofloxacin (CIP), a 500W xenon lamp is used as a light source, a sunlight simulating light source is used, the concentration of Ciprofloxacin (CIP) solution is 20mg/L, and the method comprises the following specific steps:
firstly, adding 0.04g of photocatalytic material into 70mL of Ciprofloxacin (CIP) solution at room temperature, then placing the ciprofloxacin solution into a dark box, magnetically stirring the ciprofloxacin solution for 60min to achieve adsorption-desorption balance, and taking out 4mL of solution every 10 min; then, turning on a simulated light source, and taking 4mL of solution every 10 min; centrifuging the solution taken out each time, taking supernatant, and testing the absorbance of the supernatant at the highest peak (270nm) by using a UV-2550 spectrophotometer respectively; and recovering the photocatalytic material.
FIG. 5 shows Ag/CoWO obtained in example 14/CdWO4The absorbance curve of the composite nanofiber photocatalytic material for photocatalytic degradation of Ciprofloxacin (CIP) under the irradiation of a simulated light source is shown in FIG. 6, which is CoWO prepared in comparative example 14/CdWO4The nano-fiber photocatalytic material photocatalytically degrades cyclopropyl under the irradiation of a simulated light sourceAbsorbance profile of CIP; FIG. 7 shows CoWO obtained in comparative example 24/CdWO4The powder material is used for photocatalytic degradation of an absorbance curve of ciprofloxacin under the irradiation of a simulated sunlight light source; FIG. 8 is a graph of Ag/CoWO obtained in comparative example 34/CdWO4The composite nanofiber photocatalytic material can be used for photocatalytic degradation of an absorbance curve of ciprofloxacin under the irradiation of a simulated sunlight source; the detection wavelength is 200-400 nm. As can be seen from FIGS. 5 to 8, the absorbance peak of Ciprofloxacin (CIP) solution was at 270nm, and Ag/CoWO of example 14/CdWO4After the composite nanofiber photocatalytic material is subjected to catalytic reaction for 90min under a simulated light source, the absorbance value of Ciprofloxacin (CIP) solution at 270nm is lower than that of the composite photocatalytic material in comparative examples 1-3, which shows that the silver modified CoWO prepared by the invention4/CdWO4The photocatalysis efficiency of the nano-fiber photocatalysis material is obviously improved, and the Ag/CoWO is enabled to generate the surface plasma resonance effect after silver is loaded4/CdWO4The composite nanofiber photocatalytic material has a better degradation effect on Ciprofloxacin (CIP).
Ag/CoWO obtained in example 14/CdWO4Composite nanofiber photocatalytic material, CoWO prepared in comparative example 14/CdWO4The absorbance curve of the nanofiber photocatalytic material in a dark reaction for 60min is shown in FIG. 9a, and CoWO prepared in comparative example 24/CdWO4Powder material and Ag/CoWO prepared in comparative example 34/CdWO4The absorbance curve of the composite nanofiber photocatalytic material in a dark reaction for 60min is shown in fig. 10 a. The purpose of the dark reaction is to exclude the effect of adsorption of the photocatalytic material.
And (3) calculating the photocatalytic oxidation degradation efficiency of the photocatalytic material to Ciprofloxacin (CIP) according to the formula (I).
Formula (I):
η＝[(C0-Ct)/C0]×100％，
in the formula (I), C0Absorbance, C, measured for the first time of the solutiontAbsorbance measured as time t.
The results show that the absorbance of Ciprofloxacin (CIP) solution is not substantially changed after the materials of example 1 and comparative examples 1 to 3 are subjected to the dark reaction for 10 minutes, indicating that the photocatalytic material does not catalyze degradation of Ciprofloxacin (CIP) under the dark reaction conditions.
Ag/CoWO obtained in example 14/CdWO4Composite nanofiber photocatalytic material and CoWO prepared in comparative example 14/CdWO4The absorbance change curve of the reaction solution of the nanofiber photocatalytic material under different illumination times is shown in fig. 9 b; CoWO prepared in comparative example 24/CdWO4Powder material and Ag/CoWO prepared in comparative example 34/CdWO4The absorbance change curve of the reaction solution of the composite nanofiber photocatalytic material under different illumination times is shown in fig. 10 b. One-dimensional linear structure Ag/CoWO prepared by the invention as shown in FIG. 9b and FIG. 10b4/CdWO4The composite nano-fiber photocatalytic material has obviously higher photocatalytic efficiency, and Ag/CoWO (silver-cobalt-copper) is enabled to generate surface plasma resonance effect after silver is loaded4/CdWO4The composite nanofiber photocatalytic material has a better degradation effect on Ciprofloxacin (CIP).
Application example 2
The photocatalytic degradation cycle performance of ciprofloxacin, and the catalytic degradation efficiency is calculated according to the formula (I).
Ag/CoWO prepared in example 14/CdWO4The degradation efficiency of the composite nanofiber photocatalytic material to Ciprofloxacin (CIP) by repeated recycling four times under the irradiation of a simulated light source is shown in fig. 11. CoWO prepared in comparative example 14/CdWO4The degradation efficiency of the composite photocatalytic material to Ciprofloxacin (CIP) is shown in fig. 12 after four times of repeated cyclic utilization under the irradiation of a simulated light source. Cobalt/cadmium tungstate (CoWO) prepared in comparative example 24/CdWO4) The degradation efficiency of the nano powder composite material to Ciprofloxacin (CIP) by repeated four-time cyclic utilization under the irradiation of a simulated light source is shown in fig. 13. Ag/CoWO prepared in comparative example 34/CdWO4The degradation efficiency of the composite nanofiber photocatalytic material to ciprofloxacin by repeated cyclic utilization for four times under the irradiation of a simulated sunlight light source is shown in fig. 14.
As can be seen from FIGS. 11-14, the first degradation efficiency of example 1 is as high as 93.5%, and four cyclesAfter ring utilization, Ag/CoWO prepared in example 14/CdWO4The photocatalysis effect of the composite nanofiber photocatalysis material is still high and reaches up to 90.8 percent. CoWO prepared in comparative example 14/CdWO4The first degradation efficiency of the composite photocatalytic material is 62%, and after four cycles, the degradation efficiency of a sample is reduced by about 16.9% and is only 45.1%. CoWO prepared in comparative example 24/CdWO4The first degradation efficiency of the nano powder composite material is 59.0%, and after four cycles, the degradation efficiency of a sample is reduced by about 18.9% and is only 40.1%. Ag/CoWO prepared in comparative example 34/CdWO4The first degradation efficiency of the composite nanofiber photocatalytic material is 80.3%, and after four cycles, the degradation efficiency of a sample is reduced by about 4.9% and is only 75.4%.
Comparative examples 1-3, which are inferior in both cycle performance and stability compared to the samples prepared in example 1, demonstrate that the Ag/CoWO prepared according to the present invention4/CdWO4The composite nanofiber photocatalytic material has good stability, can be recycled, and greatly reduces the production cost.
Claims (10)
1. A silver-modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material is characterized in that silver particles are loaded on the surface of cobalt tungstate/cadmium tungstate nanofibers in the microscopic morphology of the photocatalytic material.
2. The silver-modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material as claimed in claim 1, wherein the cobalt tungstate/cadmium tungstate nanofiber has a diameter of 100-400nm and a length of 5-20 μm, and the silver particles are spherical particles with a diameter of 10-20 nm.
3. The silver-modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material as claimed in claim 1, wherein the cobalt tungstate/cadmium tungstate nanofiber is prepared by preparing a spinnable precursor sol from ammonium metatungstate, cadmium acetate, cobalt nitrate and polyvinylpyrrolidone as reaction raw materials, and performing electrostatic spinning and calcination; the silver particles are formed by taking silver nitrate as a reaction raw material and depositing the silver nitrate on the cobalt tungstate/cadmium tungstate nano-fibers through a silver mirror reaction, so that a silver modified cobalt tungstate/cadmium tungstate composite nano-fiber photocatalytic material is formed;
preferably, the mol ratio of Cd to Co in the spinnable precursor sol is 1 (1-4).
4. The preparation method of the silver-modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material as claimed in claim 1, comprising the steps of:
preparing a spinnable precursor sol by taking ammonium metatungstate, cadmium acetate, cobalt nitrate and polyvinylpyrrolidone as reaction raw materials, and preparing cobalt tungstate/cadmium tungstate nano fibers by electrostatic spinning and calcining; silver nitrate is used as a reaction raw material, silver particles are deposited on the cobalt tungstate/cadmium tungstate nano-fibers through a silver mirror reaction, and thus the silver modified cobalt tungstate/cadmium tungstate composite nano-fiber photocatalytic material is formed.
5. The method for preparing the silver-modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material as claimed in claim 4, wherein the molar ratio of Cd to Co in the spinnable precursor sol is 1: (1-4);
preferably, the molar ratio of the cadmium acetate to the ammonium metatungstate is 1: (0.1667-0.3333);
preferably, the viscosity of the spinnable precursor sol is 0.1-1.0 Pa.S;
preferably, the polyvinylpyrrolidone has a weight average molecular weight of 4 to 300 ten thousand.
6. The preparation method of the silver-modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material as claimed in claim 4, wherein the receiving distance of electrostatic spinning is 10-25 cm; the spraying rate is 1.5mL/h, the voltage is 20-30kV, and the temperature is 20-25 ℃;
preferably, the calcination temperature is 500-600 ℃.
7. The preparation method of the silver-modified cobalt tungstate/cadmium tungstate composite nanofiber photocatalytic material as claimed in claim 4, wherein the mass ratio of the mole number of silver nitrate to the mass number of the cobalt tungstate/cadmium tungstate nanofibers is controlled to be (1-4): 1;
preferably, the temperature of the water bath is controlled to be 40-50 ℃ and the pH value is controlled to be 9-12 in the silver mirror reaction process, and AgNO is adopted3The concentration is 0.01-0.04M, and the concentration of glucose solution is 0.05-0.2M;
preferably, precipitating a silver nitrate solution by using sodium hydroxide, then adding ammonia water to dissolve the precipitate to obtain a silver ammonia solution, adding the cobalt tungstate/cadmium tungstate nano-fibers and dropwise adding a glucose solution to obtain the silver modified cobalt tungstate/cadmium tungstate composite nano-fiber photocatalytic material.
8. The silver-modified cadmium tungstate/cobalt tungstate composite nanofiber photocatalytic material as claimed in claim 1, which is applied to photocatalytic oxidation degradation of ciprofloxacin.
9. A method for degrading ciprofloxacin by photocatalysis, which is characterized in that the silver modified cadmium tungstate/cobalt tungstate composite nano-fiber as claimed in claim 1 is adopted as a photocatalytic material.
10. A method for photocatalytic degradation of ciprofloxacin as claimed in claim 9, comprising the steps of:
adding silver modified cadmium tungstate/cobalt tungstate composite nano-fibers as a photocatalytic material into a ciprofloxacin-containing solution, and degrading under the illumination condition; preferably, the photocatalytic degradation is carried out under light conditions while stirring.
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