A photocatalytic antibacterial material responsive to visible light and a preparation method thereof

Abstract

The present invention discloses a visible light-responsive photocatalytic antibacterial material and a preparation method thereof, and its chemical formula is: Ag2TaNb 7‑7x V 7x O 21 , where x is the molar number of vanadium ions V 5+ substituting niobium ions Nb 5+ , and 0 ≤ x ≤ 0.07. The partial substitution of niobium ions Nb 5+ by vanadium ions V 5+ in the lattice causes the optical cut-off light absorption edge of the material to redshift, broadening the light absorption wavelength range of the material in the visible light region; at the same time, the lattice perturbation brought about by doping also improves the separation efficiency of photo-generated charges, not only further enhancing the photocatalytic performance, but also broadening the light response range, achieving a significant improvement in the antibacterial effect under visible light irradiation. The preparation method of the material of the present invention is simple and easy to implement, the raw materials are easily available, the cost is low, the preparation method is pollution-free, its photocatalytic antibacterial activity is high, and it has good application prospects in the antibacterial inactivation of Escherichia coli and Staphylococcus epidermidis.

Description

Technical Field

[0001] The present invention belongs to the technical field of antibacterial materials, and relates to a photocatalytic antibacterial material responsive to visible light and a preparation method thereof. Background Art

[0002] In recent years, photocatalytic technology has become one of the research hotspots worldwide in dealing with the increasingly serious environmental pollution and energy crisis. The research on photocatalytic materials represented by oxide semiconductors such as titanium dioxide and zinc oxide has received extensive attention. The developed photocatalytic antibacterial technology is a potential green antibacterial technology. Semiconductor materials absorb light energy and generate photo-generated charges, producing hydroxyl radicals, superoxide radicals, etc. on the surface of the material. These radicals can destroy the cell structure of bacteria, achieving the effect of eliminating bacteria, and the resulting products are also non-toxic and side-effect-free. Antibacterial based on this technology will not cause microorganisms to develop drug resistance and tolerance, and has the advantages of high efficiency, safety, and environmental protection. Most classic oxide semiconductor photocatalytic materials, such as titanium dioxide, tungsten trioxide, niobium oxide, zinc oxide, etc., have a wide band gap and can only absorb ultraviolet-near ultraviolet light, with the utilization rate of solar energy less than 10%, which greatly limits the utilization rate of sunlight. Therefore, developing semiconductor materials with efficient visible light response is of crucial significance for the development of photocatalytic antibacterial. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a photocatalytic antibacterial material responsive to visible light and a preparation method thereof. The photocatalytic antibacterial material is a vanadium-doped silver niobium tantalate, and its chemical formula is: Ag2TaNb 7-7x V 7x O 21 , where x is the molar number of vanadium ions V 5+ substituting niobium ions Nb 5+ , and 0 ≤ x ≤ 0.07. The photocatalytic antibacterial material of the present invention is prepared by a simple high-temperature solid-phase method. The method has simple operation, mild reaction conditions, short time consumption, and the prepared material has uniform particles, high photocatalytic antibacterial activity, and good inactivation effect on Escherichia coli and Staphylococcus epidermidis.

[0004] According to the first aspect of the present invention, the present invention provides a photocatalytic antibacterial material responsive to visible light, and its chemical general formula is Ag2TaNb 7-7x V 7x O 21 , where x is the molar number of vanadium ions V 5+ substituting niobium ions Nb 5+ , and 0 ≤ x ≤ 0.07.

[0005] According to another aspect of the present invention, the present invention provides a method for preparing a photocatalytic antibacterial material responsive to visible light, comprising the following steps:

[0006] (1) According to the requirements of the element stoichiometric ratio in the chemical formula Ag2TaNb 7-7x V 7x O 21 , weigh compounds containing silver ions (Ag + ), compounds containing tantalum ions (Ta 5+ ), compounds containing niobium ions (Nb 5+ ), and compounds containing vanadium ions (V 5+ ); grind and mix the weighed compounds evenly to obtain a uniform mixture; where 0≤x≤0.07;

[0007] (2) Calcinate the mixture obtained in step (1) under an air atmosphere, with the pre-calcination temperature being 350 - 650 °C and the pre-calcination time being 1 - 10 hours;

[0008] (3) After the pre-calcined mixture obtained in step (2) is naturally cooled, grind and mix it evenly again, and perform a second pre-calcination in an air atmosphere, with the pre-calcination temperature being 650 - 850 °C and the pre-calcination time being 1 - 10 hours.

[0009] (4) After the second pre-calcined mixture obtained in step (3) is naturally cooled, grind and mix it evenly again, and calcine it in an air atmosphere, with the calcination temperature being 850 - 1050 °C and the calcination time being 3 - 10 hours. After the calcined product is naturally cooled, a photocatalytic antibacterial material responsive to visible light is obtained.

[0010] In one embodiment of the present invention, the compound containing silver ions Ag + is silver oxide, silver hydroxide, silver chloride, silver nitrate, preferably silver oxide Ag2O.

[0011] In one embodiment of the present invention, the compound containing tantalum ions Ta 5+ is one of tantalum pentoxide, tantalum hydroxide, and tantalum chloride, preferably tantalum pentoxide Ta2O5.

[0012] In one embodiment of the present invention, the compound containing niobium ions Nb 5+ is one of niobium pentoxide, niobium hydroxide, and niobium chloride, preferably niobium pentoxide Nb2O5.

[0013] In one embodiment of the present invention, the compound containing vanadium ions V 5+ is one of vanadium pentoxide and ammonium metavanadate, preferably ammonium metavanadate NH4VO3.

[0014] In one embodiment of the present invention, the preferred temperature for the pre-calcination in step (4) is 900 - 1000 °C, and the preferred time for the pre-calcination is 4 - 7 hours.

[0015] According to the third aspect of the present invention, the present invention provides a use of a visible light-responsive photocatalytic antibacterial material for inactivating Escherichia coli and Staphylococcus epidermidis under the irradiation of visible light.

[0016] In one embodiment of the present invention, the visible light-responsive photocatalytic antibacterial material is Ag2TaNb 6.51 V 0.49 O 21 、Ag2TaNb 6.65 V 0.35 O 21 、Ag2TaNb 6.93 V 0.07 O 21 or Ag2TaNb7O 21 .

[0017] Compared with the prior art, the present invention has the following remarkable advantages:

[0018] 1) Compared with similar materials, the electronic structure advantage of the material of the present invention is that through the doping of vanadium ions in the silver niobate tantalate matrix, the hybridization of (V3d + Ag4d + O2p) in the valence band of the semiconductor greatly reduces the band gap of the semiconductor and broadens the visible light response range; due to the doping of impurity ions, certain defects are also brought, thereby inhibiting the recombination of photo-generated electrons and holes, and a material with high visible light utilization rate, low recombination rate of photo-generated electrons and holes, and excellent photocatalytic antibacterial performance is prepared.

[0019] 2) The antibacterial material of the present invention has good antibacterial performance against Escherichia coli and Staphylococcus epidermidis under visible light.

[0020] 3) The preparation process of the matrix material of the present invention is simple, the reaction conditions are mild, the preparation principle is simple, it is easy to operate, and the required preparation equipment for the product is common, which is convenient for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Attached Figure 1 is a comparison of the XRD diffraction patterns of the samples prepared in Examples 1, 2, 3, and 4 of the present invention with the X-ray diffraction standard card PDF#21 - 1085;

[0022] Attached Figure 2 is the SEM image of the sample prepared in Example 1 of the present invention;

[0023] Attached Figure 3 is the light absorption spectrum of the samples prepared in Examples 1, 2, 3, and 4 of the present invention;

[0024] Appendix Figure 4 This shows the degradation effect of the samples prepared in Examples 1, 2, 3, and 4 of the present invention on methylene blue dye under visible light irradiation. Detailed implementation manners

[0025] The photocatalytic activity of the photocatalytic antibacterial material of the present invention is implemented by the following method:

[0026] In the photocatalytic experiment in the examples, the degradation activity of methylene blue under visible light irradiation was used for evaluation. The photocatalytic instrument used was the XPA-2 photoreactor produced by Nanjing Xujiang Electromechanical Factory, the light source lamp was a 500-watt cylindrical xenon lamp, and the temperature of the photocatalytic reaction was room temperature. The amount of photocatalytic material used in each experiment was 100 mg, the total solution volume was 250 mL, and the concentration of organic methylene blue was 10 mg / L. The catalyst was added to the reaction solution, and the reaction time was 120 minutes; after turning on the condensed water, the light was randomly turned on, and samples were taken at regular intervals after light irradiation. After centrifugal separation, the upper clear liquid was aspirated, and the light absorption of the methylene blue solution was measured with a UV-visible spectrophotometer at a wavelength of 650 - 670 nm. According to the Lambert-Beer law, the absorbance of the solution is proportional to the concentration. Therefore, the removal rate can be calculated by substituting the absorbance for the concentration, and this is used as the removal rate of the methylene blue solution. Calculation formula: Degradation rate = (1 - C / C0) × 100% = (1 - A / A0) × 100%, where C0 and C are the concentrations before and after photocatalytic degradation respectively, and A0 and A are the absorbance values before and after degradation respectively.

[0027] The inactivation effect of the photocatalytic antibacterial material of the present invention on bacteria is implemented by the following method:

[0028] The antibacterial properties of the photocatalytic antibacterial materials prepared according to the technical solutions of Examples 1, 2, 3, and 4 were studied respectively, and the bacteria not treated with the samples of the examples were used as blank controls for comparison. First, Staphylococcus epidermidis and Escherichia coli were cultured to the logarithmic phase, and they were slowly washed with sterile normal saline (0.9% NaCl) solution respectively to adjust the bacterial density in the solution to 10 5 CFU / mL. 10 mg of the samples prepared in the examples were weighed respectively and added to 50 mL of the bacterial solution with the above bacteria, and magnetic stirring was maintained for photocatalytic antibacterial testing. The light source was a 300W xenon lamp equipped with a 420nm filter, and the light intensity was 40 mW / cm 2 . After 60 minutes of light irradiation, a certain amount of the mixed bacterial solution was taken, diluted and spread on the LB solid medium, and placed in a biochemical incubator at 37°C for 16 hours of incubation. Then, the colony number in the bacterial solution after different light irradiation times was counted by the counting method. The antibacterial experimental results of Examples 1, 2, 3, and 4 on Escherichia coli and Staphylococcus epidermidis under visible light catalysis are shown in Table 1.

[0029] Table 1 Survival rates of bacteria after photocatalytic treatment of the samples prepared in Examples 1, 2, 3, and 4 for 60 minutes

[0030]

[0031]

[0032] Example 1:

[0033] According to the molar ratios of the elements in the chemical formula Ag2TaNb 6.51 V 0.49 O 21 Weigh out 1.853 g of silver oxide Ag2O, 1.768 g of tantalum pentoxide Ta2O5, 6.921 g of niobium pentoxide Nb2O5, and 0.458 g of ammonium metavanadate NH4VO3 respectively; mix the above raw materials in an agate mortar, grind and mix them evenly, then carry out the first pre-calcination in an air atmosphere, the pre-calcination temperature is 350 °C, the pre-calcination time is 10 hours, then cool to room temperature and take out the sample; mix and grind the raw materials of the first calcination evenly again, and carry out the pre-calcination again in an air atmosphere, the pre-sintering temperature is 650 °C, and the pre-calcination time is 10 hours; cool the raw materials of the second calcination to room temperature, mix and grind them evenly again, and calcine in an air atmosphere, the calcination temperature is 1050 °C, and the calcination time is 3 hours, then cool to room temperature, and a photocatalytic antibacterial material responsive to visible light is obtained.

[0034] See Appendix Figure 1 , which is the X-ray powder diffraction pattern of the sample prepared according to the technical scheme of Example 1. The results show that the prepared material is a single-phase material without any other impurity phases. See Appendix Figure 2 , which is the SEM image of the sample prepared according to the technical scheme of Example 1. The sintered sample is spherical, with uniform size, and the particle diameter mostly distributes in the range of 5 - 10 microns. See Appendix Figure 3 , which is the ultraviolet-visible light absorption spectrum of the sample prepared according to the technical scheme of Example 1. It can be seen that due to the doping of vanadium ions, the wavelength of the light absorbed by the sample is greatly redshifted, and the amount of visible light that can be absorbed increases. See Appendix Figure 4 , which is the degradation curve of methylene blue by the sample prepared according to the technical scheme of Example 1. It can be seen from the figure that the degradation rate of the photocatalytic degradation of methylene blue by this sample can reach more than 95% in 90 minutes, and this material has high photocatalytic activity. See Table 1, which is the survival rate of bacteria after photocatalytic treatment of the sample prepared in Example 1 for 60 minutes. The results show that after 60 minutes of visible light irradiation, compared with the control group, the antibacterial activities of the sample prepared in Example 1 against Escherichia coli and Staphylococcus epidermidis are 100%.

[0035] Example 2:

[0036] According to the molar ratio of elements in the chemical formula Ag2TaNb 6.65 V 0.35 O 21 Weigh 2.317 g of silver oxide Ag2O, 2.210 g of tantalum pentoxide Ta2O5, 8.838 g of niobium pentoxide Nb2O5, and 0.409 g of ammonium metavanadate NH4VO3 respectively; mix the above raw materials in an agate mortar, grind and mix them evenly, then conduct the first pre-calcination in an air atmosphere. The pre-calcination temperature is 650 °C, and the pre-calcination time is 1 hour. Then cool to room temperature and take out the sample; mix and grind the raw materials of the first calcination evenly again, and conduct the pre-calcination again in an air atmosphere. The pre-sintering temperature is 850 °C, and the pre-calcination time is 1 hour; cool the raw materials of the second calcination to room temperature, mix and grind them evenly again, and calcine in an air atmosphere. The calcination temperature is 850 °C, and the calcination time is 10 hours. Then cool to room temperature to obtain a photocatalytic antibacterial material that responds to visible light.

[0037] See Appendix Figure 1 , which is the X-ray powder diffraction pattern of the sample prepared by the technical solution of Example 2. The results show that the prepared material is a single-phase material and there is no presence of any other impurity phases. See Appendix Figure 3 , which is the ultraviolet-visible light absorption spectrum of the sample prepared according to the technical solution of Example 2. It can be seen that the light absorption wavelength of the sample is mainly in the ultraviolet and visible light ranges. See Appendix Figure 4 , which is the degradation curve of methylene blue by the sample prepared according to the technical solution of Example 2. It can be seen from the figure that the degradation rate of the photocatalytic degradation of methylene blue by this sample can reach more than 95% in 120 minutes, and this material has high photocatalytic activity. See Table 1, which is the survival rate of bacteria after 60 minutes of photocatalytic treatment of the sample prepared in Example 2. The results show that after visible light irradiation for minutes, compared with the control group, the sample prepared in Example 2 almost completely eliminates Escherichia coli and Staphylococcus epidermidis.

[0038] Example 3:

[0039] According to the chemical formula Ag2TaNb 6.93 V 0.07 O 21For the molar ratios of the elements in [the compound], weigh out silver oxide Ag₂O: 3.707 g, tantalum pentoxide Ta₂O₅: 3.536 g, niobium pentoxide Nb₂O₅: 14.736 g, and ammonium metavanadate NH₄VO₃: 0.131 g respectively; mix the above raw materials in an agate mortar, grind and mix them evenly, then conduct the first pre-calcination in an air atmosphere. The pre-calcination temperature is 450 °C and the pre-calcination time is 3 hours. Then cool to room temperature and take out the sample; mix and grind the raw materials of the first calcination evenly again, conduct the pre-calcination again in an air atmosphere, the pre-sintering temperature is 750 °C and the pre-calcination time is 5 hours; cool the raw materials of the second calcination to room temperature, mix and grind them evenly again, and conduct the calcination in an air atmosphere. The calcination temperature is 1000 °C and the calcination time is 4 hours. Then cool to room temperature to obtain a visible light-responsive photocatalytic antibacterial material.

[0040] See Appendix Figure 1 , which is the X-ray powder diffraction pattern of the sample prepared by the technical solution of Example 3. The results show that the prepared material is a single-phase material and there is no presence of any other impurity phases. See Appendix Figure 3 , which is the ultraviolet-visible light absorption spectrum of the sample prepared according to the technical solution of Example 3. It can be seen that the light absorption wavelength of the sample is mainly in the ultraviolet and visible light ranges. See Appendix Figure 4 , which is the degradation curve of methylene blue by the sample prepared according to the technical solution of Example 3. It can be seen from the figure that the degradation rate of the photocatalytic degradation of methylene blue by this sample can reach more than 90% in 150 minutes, and this material has high photocatalytic activity. See Table 1, which is the survival rate of bacteria after 60 minutes of photocatalytic treatment of the sample prepared in Example 3. The results show that after visible light irradiation for [X] minutes, compared with the control group, the sample prepared in Example 3 almost completely eliminates Escherichia coli and Staphylococcus epidermidis.

[0041] Example 4:

[0042] According to the chemical formula Ag₂TaNb₇O 21 For the molar ratios of the elements in [the compound], weigh out silver oxide Ag₂O: 2.086 g, tantalum pentoxide Ta₂O₅: 1.989 g, niobium pentoxide Nb₂O₅: 8.373 g respectively; mix the above raw materials in an agate mortar, grind and mix them evenly, then conduct the first pre-calcination in an air atmosphere. The pre-calcination temperature is 550 °C and the pre-calcination time is 3 hours. Then cool to room temperature and take out the sample; mix and grind the raw materials of the first calcination evenly again, conduct the pre-calcination again in an air atmosphere, the pre-sintering temperature is 850 °C and the pre-calcination time is 5 hours; cool the raw materials of the second calcination to room temperature, mix and grind them evenly again, and conduct the calcination in an air atmosphere. The calcination temperature is 950 °C and the calcination time is 5 hours. Then cool to room temperature to obtain a visible light-responsive photocatalytic antibacterial material.

[0043] See the appendix Figure 1 , which is the X-ray powder diffraction pattern of the sample prepared by the technical solution of Example 4. The results show that the prepared material is a single-phase material and there is no presence of any other impurity phases. See the appendix Figure 3 , which is the ultraviolet-visible absorption spectrum of the sample prepared according to the technical solution of Example 4. From the light absorption of the sample, the effective effect of vanadium ion doping on reducing the semiconductor bandgap can be experimentally verified. See the appendix Figure 4 , which is the degradation curve of methylene blue by the sample prepared according to the technical solution of Example 4. It can be seen from the experimental data that vanadium ion doping can greatly improve the photocatalytic activity of the material. See Table 1, which is the survival rate of bacteria after 60 minutes of photocatalytic treatment of the sample prepared in Example 4. The results show that vanadium ion doping can greatly improve the inactivation efficiency of the sample against Escherichia coli and Staphylococcus epidermidis.

[0044] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A photocatalytic antibacterial material responsive to visible light, with the chemical general formula Ag2TaNb 7-7x V 7x O 21 , where x is the mole number of vanadium ions V 5+ substituting niobium ions Nb 5+ , and 0 < x ≤ 0.

07.

2. A method for preparing a visible-light-responsive photocatalytic antibacterial material according to claim 1, comprising the following steps: (1) According to the requirements of the element stoichiometric ratio in the chemical formula Ag2TaNb 7-7x V 7x O 21 , weigh a compound containing silver ions, a compound containing tantalum ions, a compound containing niobium ions, and a compound containing vanadium ions; grind and mix the weighed compounds evenly to obtain a uniform mixture; where 0 < x ≤ 0.07; (2) Calcining the mixture obtained in step (1) under an air atmosphere, with a calcination temperature of 350 - 650 °C and a calcination time of 1 - 10 hours; (3) After the pre-calcined mixture obtained in step (2) is naturally cooled, it is ground and mixed evenly again, and then subjected to a second calcination in an air atmosphere, with a calcination temperature of 650 - 850 °C and a calcination time of 1 - 10 hours; (4) After the second pre-calcined mixture obtained in step (3) is naturally cooled, it is ground and mixed evenly again, and then calcined in an air atmosphere, with a calcination temperature of 850 - 1050 °C and a calcination time of 3 - 10 hours. After the calcined product is naturally cooled, a visible-light-responsive photocatalytic antibacterial material is obtained.

3. The method according to claim 2, characterized in that: The compound containing silver ion Ag + is silver oxide, silver hydroxide, silver chloride, silver nitrate.

4. The method according to claim 3, wherein: The compound containing silver ion Ag + is silver oxide Ag2O.

5. The method according to claim 2, wherein: The described compound containing tantalum ion Ta 5+ is one of tantalum pentoxide, tantalum hydroxide, and tantalum chloride.

6. The method according to claim 5, characterized in that: The described compound containing tantalum ion Ta 5+ is tantalum pentoxide Ta2O5.

7. The method according to claim 2, wherein: The described compound containing niobium ion Nb 5+ is one of niobium pentoxide, niobium hydroxide and niobium chloride.

8. The method according to claim 7, wherein: The described compound containing niobium ions Nb 5+ is niobium pentoxide Nb2O5.

9. The method according to claim 2, wherein: The described compound containing vanadium ion V 5+ is one of vanadium pentoxide and ammonium metavanadate.

10. The method according to claim 9, wherein: The described compound containing vanadium ion V 5+ is ammonium metavanadate NH4VO3.

11. The method according to claim 2, wherein: The pre-calcination temperature in step (4) is 900 - 1000 °C, and the pre-calcination time is 4 - 7 hours.

12. Use of a visible-light-responsive photocatalytic antibacterial material according to claim 1 for inactivating Escherichia coli and Staphylococcus epidermidis under visible light irradiation.

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