Vapor Phase Sterilization Method of Bismuth Tungstate Photocatalytic Coating Coupled with Three-Dimensional Fiber Filter Material

Abstract

The present invention provides a gas phase sterilization method of a bismuth tungstate photocatalytic coating coupled with a three-dimensional fiber filter material, belonging to the technical field of chemical methods and air sterilization. The gas phase sterilization reactor comprises: a cavity defining the gas phase sterilization reactor; a Bi coated on the inner wall of the cavity; 2.15 WO6 photocatalytic coating, a three-dimensional fiber filter material fixed on the inner wall of the cavity and covering the entire cross-section of the cavity, the three-dimensional fiber filter material having a tree-like structure distributed along the air flow direction; and a 2.15 The WO6 photocatalytic coating provides the ultraviolet light source for ultraviolet light irradiation. Under ultraviolet light irradiation, Bi 2.15 The WO6 photocatalytic coating produces active substances that in situ catalyze the moisture in the air of the gas phase sterilization reactor. The produced hydrogen peroxide is captured and dispersed on the tree-like structure surface of the three-dimensional fiber filter material, thereby utilizing ultraviolet light irradiation, photocatalytic reaction and coupled three-dimensional fiber filter material filtration to achieve gas phase sterilization.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical method and air sterilization, and in particular relates to a gas phase sterilization method of a bismuth tungstate photocatalytic coating coupled with a three-dimensional fiber filter material. Background Art

[0002] In recent years, respiratory diseases caused by airborne viruses have continuously threatened human health. In closed indoor air, aerosols account for a large proportion, and it is necessary to develop more environmentally friendly and cost-effective gas phase sterilization methods to control the spread of microorganisms and reduce the rate of airborne infection.

[0003] Although physical methods such as high-efficiency air purifiers (HEPA) and electrostatic adsorption can capture bioaerosols attached to air particles, they are ineffective in capturing bioaerosols with a particle size less than 100 nm. When bioaerosols retained on the filter surface are not completely inactivated, they will become a new source of pollution. Compared with physical methods, ultraviolet (UV) irradiation has the advantage of a broad spectrum. Photons can effectively destroy the DNA and molecular structure of bacteria and reduce the reproductive capacity of bacteria without producing by-products. However, UV irradiation can cause bacteria to enter a viable but uncultivable state. Uninactivated bacteria can be reactivated under light activation and dark repair. In addition, considering that bioaerosols with larger particle sizes usually carry more bacteria, higher doses of UV irradiation are required during the sterilization process, resulting in higher energy consumption. Summary of the invention

[0004] In view of the above technical problems, the present invention provides a gas phase sterilization method of a bismuth tungstate photocatalytic coating coupled with a three-dimensional fiber filter material, in order to at least partially solve the above technical problems. In this regard, the technical solution provided by the present invention is as follows.

[0005] According to an embodiment of the present invention, a gas phase sterilization method of a bismuth tungstate photocatalytic coating coupled with a three-dimensional fiber filter material is provided. The gas phase sterilization method adopts a gas phase sterilization reactor, which comprises: a cavity defining an internal space of the gas phase sterilization reactor; Bi coated on the inner wall of the cavity 2.15 WO6 photocatalytic coating, a three-dimensional fiber filter material fixed on the inner wall of the cavity and covering the entire cross-section of the cavity, the three-dimensional fiber filter material having a tree-like structure distributed along the air flow direction; and a 2.15 The WO6 photocatalytic coating provides an ultraviolet light source for ultraviolet light irradiation.

[0006] The gas phase sterilization method includes: under ultraviolet light, Bi coated on the inner wall of the cavity 2.15The WO6 photocatalytic coating generates active substances in situ, and the active substances react with the moisture in the air of the gas phase sterilization reactor in situ. The generated hydrogen peroxide is captured by the three-dimensional fiber filter material with a tree-like structure distributed along the air flow direction and dispersed on the tree-like structure surface of the three-dimensional fiber filter material, thereby utilizing ultraviolet light irradiation, Bi 2.15 The photocatalytic reaction of WO6 photocatalytic coating is coupled with three-dimensional fiber filter filtration to achieve gas phase sterilization.

[0007] In an embodiment of the present invention, the cavity defining the internal space of the gas phase sterilization reactor is coated with Bi on the inner wall of the cavity. 2.15 WO6 photocatalytic coating is arranged inside the cavity to provide Bi 2.15 The WO6 photocatalytic coating provides a UV light source for UV irradiation and constructs a photocatalytic reaction site so that Bi 2.15 The WO6 photocatalytic coating generates active substances in situ under ultraviolet light irradiation, and the active substances catalyze the moisture in the air in situ to produce highly oxidizing hydrogen peroxide (H2O2). By fixing the three-dimensional fiber filter material on the inner wall of the cavity and covering the entire cross-section of the cavity, and utilizing the high specific surface area and tree-like structure of a certain thickness of the three-dimensional fiber filter material, while intercepting larger particle size particles and pathogens in the bioaerosol, the hydrogen peroxide generated in situ by the photocatalytic reaction can be captured and dispersed. Through the gas phase sterilization method of the present invention, in the gas phase sterilization reactor, the bacteria in the bioaerosol with a larger particle size intercepted on the three-dimensional fiber filter material can be effectively sterilized, and the bacteria in the bioaerosol that passes through the three-dimensional fiber filter material can be sterilized, thereby achieving full-size bioaerosol sterilization and improving the overall sterilization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a schematic diagram of the structure of a gas phase sterilization reactor of a bismuth tungstate photocatalytic coating coupled with a three-dimensional fiber filter material in an embodiment of the present invention;

[0009] Figure 2 3 is a physical picture of the three-dimensional fiber filter material in the embodiment of the present invention, wherein a is a physical picture of the cross section of the three-dimensional fiber filter material, and b is a local magnified scanning electron microscope (SEM) picture of the three-dimensional fiber filter material in a;

[0010] Figure 3 Bi in the embodiment of the present invention 2.15 SEM image of WO6 photocatalyst, where a is Bi 2.15 SEM image of WO6 photocatalyst, b is Bi in a 2.15 Local magnified SEM image of WO6 photocatalyst;

[0011] Figure 4 Schematic diagram of the gas phase sterilization principle of the bismuth tungstate photocatalytic coating coupled with the three-dimensional fiber filter material in the embodiment of the present invention;

[0012] Figure 5 The logarithmic sterilization efficiency diagrams of the Gram-negative bacteria Escherichia coli (E. coli) and the Gram-positive bacteria Staphylococcus aureus (S. aureus) in Example 1 and Comparative Examples 1-7 of the present invention, wherein a is a logarithmic sterilization efficiency diagram of E. coli under ultraviolet light and ultraviolet photocatalytic reaction conditions; b is a logarithmic sterilization efficiency diagram of E. coli under ultraviolet light, ultraviolet photocatalytic reaction coupled with three-dimensional fiber filter material filtration conditions; c is a logarithmic sterilization efficiency diagram of S. aureus under ultraviolet light and ultraviolet photocatalytic reaction conditions; d is a logarithmic sterilization efficiency diagram of S. aureus under ultraviolet light, ultraviolet photocatalytic reaction coupled with three-dimensional fiber filter material filtration conditions;

[0013] Figure 6 The stability test effect diagram of the gas phase sterilization reactor for S. aureus in Example 1 of the present invention and Comparative Example 7 is shown;

[0014] Figure 7 The amount of H2O2 produced and the ultraviolet-visible light absorption spectrum of the present invention, wherein a is the UV / Bi 2.15 b is the UV-visible absorption spectrum of the amount of H2O2 produced over time under the WO6 sterilization system, and b is the linear relationship between the amount of H2O2 produced and the logarithmic sterilization efficiency;

[0015] Figure 8 The graphs of the production of H2O2 and the logarithmic sterilization efficiency at different relative humidities of the present invention are shown in FIG. a, wherein a is a graph of the production of H2O2 at different relative humidities, and b is a graph of the logarithmic sterilization efficiency of S. aureus at different relative humidities;

[0016] Fig. 9 In the embodiment of the present invention, Bi2WO6 and Bi 2.15 Raman spectrum of WO6 under ultraviolet light.

[0017] Reference numerals

[0018] 1-gas phase sterilization reactor, 2-first air pump, 3-purification device, 4-bioaerosol generator, 5-second air pump, 6-adjustable flow control valve, 7-mixing tank, 8-collection bottle, 9-sampling pump, 101-chamber, 102-Bi 2.15 WO6 photocatalytic coating, 103- three-dimensional fiber filter material, 104- ultraviolet light source. DETAILED DESCRIPTION

[0019] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0020] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The term "comprising" used herein indicates the existence of features, steps, operations, but does not exclude the existence or addition of one or more other features.

[0021] In the case of using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.). In the case of using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, or C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0022] Under ultraviolet light, photocatalysts produce oxidative free radicals, which can destroy the structure of microorganisms in the air and achieve gas phase sterilization. Titanium dioxide (TiO2) has been widely used in microbial sterilization, but its low photogenerated electron-hole yield and easy electron-hole recombination have limited its application in gas phase sterilization to a certain extent. Compared with TiO2, bismuth tungstate compounds (Bi 2+x WO6 (x represents the excess of Bi) is a group of bimetallic oxides with a band gap of less than 2.8 eV and high photocatalytic activity. Although the traditional Bi2WO6 has photocatalytic performance, its catalytic performance is not high. In this regard, the present invention proposes to adjust Bi by self-doping without introducing impurity elements. 2+x Compared with Bi2WO6, self-doped Bi 2.15 WO6 has a narrower band gap (2.72 eV) and higher visible light photocatalytic activity.

[0023] Although ultraviolet light can inactivate bacteria, for larger-sized bioaerosols carrying more bacteria, a higher dose of ultraviolet light is required during the sterilization process, which consumes more energy. In this regard, the present invention utilizes the unique tree-like structure and specific surface area of ​​the three-dimensional fiber filter material to intercept larger-sized bioaerosols while 2.15 The hydrogen peroxide generated by the photocatalytic reaction of the WO6 photocatalytic coating is captured and dispersed on the three-dimensional fiber filter material to achieve the sterilization of the biological aerosols with larger particle sizes intercepted on the three-dimensional fiber filter material; the high light transmittance of the three-dimensional fiber filter material can achieve ultraviolet light sterilization while reducing the loss of ultraviolet light. Based on this, the present invention proposes to combine the chemical sterilization of ultraviolet light and photocatalytic reaction with the physical filtration of the three-dimensional fiber filter material to control the biological aerosols in the gas phase. The gas phase sterilization method of the present invention is an economical, suitable and flexible technical solution.

[0024] Figure 1 This is a schematic diagram of the structure of a gas phase sterilization reactor with a bismuth tungstate photocatalytic coating coupled with a three-dimensional fiber filter material in an embodiment of the present invention.

[0025] According to an embodiment of the present invention, the gas phase sterilization method of the bismuth tungstate photocatalytic coating coupled with the three-dimensional fiber filter material adopts the following method: Figure 1 The gas phase sterilization reactor 1 shown in the figure comprises: a cavity 101 defining the internal space of the gas phase sterilization reactor 1; a Bi 2.15 WO6 photocatalytic coating 102, a three-dimensional fiber filter material 103 fixed on the inner wall of the cavity 101 and covering the entire cross-section of the cavity 101, the three-dimensional fiber filter material 103 having a tree-like structure distributed along the air flow direction; and a three-dimensional fiber filter material 103 distributed in the cavity 101 for transmitting Bi 2.15 The WO6 photocatalytic coating 102 provides an ultraviolet light source 104 for ultraviolet light irradiation.

[0026] The gas phase sterilization method includes: under ultraviolet light irradiation, Bi coated on the inner wall of the cavity 101 2.15 The WO6 photocatalytic coating 102 generates active substances in situ, and the active substances react with the moisture in the air of the gas phase sterilization reactor 1 in situ to catalyze the generated hydrogen peroxide. The generated hydrogen peroxide is captured by the three-dimensional fiber filter material 103 having a tree-like structure distributed along the air flow direction and dispersed on the tree-like structure surface of the three-dimensional fiber filter material 103, thereby utilizing ultraviolet light irradiation, Bi 2.15 The photocatalytic reaction of the WO6 photocatalytic coating 102 is coupled with the filtration of the three-dimensional fiber filter material 103 to achieve gas phase sterilization.

[0027] In the embodiment of the present invention, Bi is coated on the inner wall of the cavity 101 in the internal space of the gas phase sterilization reactor 1. 2.15 The WO6 photocatalytic coating 102 is arranged inside the cavity 101 to provide Bi2.15 The WO6 photocatalytic coating 102 provides an ultraviolet light source 104 for ultraviolet light irradiation, thereby constructing a photocatalytic reaction site so that Bi 2.15 The WO6 photocatalytic coating 102 produces more active substances under the irradiation of the ultraviolet light source 104. By fixing the three-dimensional fiber filter material 103 on the inner wall of the cavity 101 and covering the entire cross-section of the cavity 101, the three-dimensional fiber filter material 103 has a high specific surface area and a unique tree-like structure, while physically intercepting the particulate matter and pathogens in the biological aerosol with a larger particle size, it can capture the oxidizing hydrogen peroxide generated by in-situ catalysis of the moisture in the air inside the cavity 101 of the gas phase sterilization reactor 1, and disperse it on the surface of the three-dimensional fiber filter material 103, and sterilize the biological aerosol with a larger particle size intercepted on the three-dimensional fiber filter material 103; and the hydrogen peroxide that passes through the three-dimensional fiber filter material 103 can cooperate with ultraviolet light to achieve gas phase sterilization of the entire gas phase sterilization reactor 1, and then completely kill the biological aerosol of all particle sizes in the gas phase sterilization reactor 1.

[0028] In the conventional sterilization method using ultraviolet light, the ultraviolet light causes the bacteria to be alive but uncultivable. The inactivated bacteria are reactivated under light or repaired in a dark environment. In this regard, the present invention utilizes the unique tree-like structure of the three-dimensional fiber filter material 103 and has a certain elasticity. It is preferred that the ultraviolet light source 104 penetrates the three-dimensional fiber filter material 103 and is parallel to the gas phase sterilization reactor 1 and Bi 2.15 WO6 photocatalytic coating 102 (such as Figure 1 As shown in FIG. 1 ), the ultraviolet light source 104 is a 254nm H-type mercury lamp. The aforementioned ultraviolet light source 104 is arranged in a structure to effectively increase the contact area of ​​the photocatalytic reaction. The unique tree-like structure does not shield the ultraviolet light source 104 and prolongs the time of the bioaerosol intercepted inside the tree-like structure and the photocatalytic oxidation sterilization or ultraviolet light sterilization, thereby maximizing the photocatalytic effect and improving the sterilization efficiency of the entire gas phase sterilization reactor 1.

[0029] Figure 2 3 is a physical picture of the three-dimensional fiber filter material in an embodiment of the present invention, wherein a is a physical picture of a cross section of the three-dimensional fiber filter material, and b is a local magnified scanning electron microscope (SEM) picture of the three-dimensional fiber filter material in a.

[0030] like Figure 2As shown, the three-dimensional fiber filter material 103 includes a plurality of independent knitted surface layers, and a spacer yarn that spatially fixes and connects each two independent knitted surface layers, and the spacer yarn has a tree-like structure distributed along the air flow direction. The two independent knitted surface layers are fixed and kept separated from each other by the spacer yarn having a tree-like structure, which is convenient for assembly and maintenance on the one hand, and can provide a larger contact area on the other hand, so that the three-dimensional fiber filter material 103 is easy to contact with the bioaerosol and hydrogen peroxide generated by photocatalysis, thereby improving the sterilization efficiency.

[0031] According to an embodiment of the present invention, by arranging the three-dimensional fiber filter material 103 with a tree-like structure along the air flow direction, the air permeability is increased while the air resistance is reduced. When the wind speed is 1-2.5 m / s, the pressure drop of the three-dimensional fiber filter material 103 is 20-50 Pa, and the air resistance is low, which effectively avoids the problem of increased air resistance caused by the use of the gas phase sterilization reactor 1, which affects the efficiency of air purification. In order to achieve a large air volume (rated air volume 900-1300m 3 / h) air purification. The material of the three-dimensional fiber filter material 103 in the present invention is selected from polyethylene terephthalate (PET), and the knitted surface layer and the spacer yarn with a three-dimensional tree-like structure are woven from PET yarn, so that the three-dimensional fiber filter material 103 has a three-dimensional tree-like structure and has a certain elasticity, and can effectively fit with the ultraviolet light source 104. The fibers constituting the tree-like structure of the three-dimensional fiber filter material 103 have a diameter of 44.4±10.2μm, and each fiber is staggered. By utilizing the larger diameter of the three-dimensional fiber filter material 103, swinging caused by the impact of air flow during application is avoided. The thickness of the three-dimensional fiber filter material 103 is 3.0~20.0mm, the porosity is 90~95%, and the mass per unit area is 200~260g / m 2 By utilizing the moderate thickness, porosity and specific surface area of ​​the three-dimensional fiber filter material 103, the obtained three-dimensional fiber filter material 103 has good support, high dust holding capacity, light transmittance and the function of accommodating active substances, thereby increasing the contact area and interaction time with the bioaerosol, and helping to improve the overall sterilization efficiency of the gas phase sterilization reactor 1. In an embodiment of the present invention, the three-dimensional fiber filter material 103 is one or more, and the multiple three-dimensional fiber filter materials 103 are evenly spaced to enhance the bactericidal performance of gas phase sterilization.

[0032] According to an embodiment of the present invention, Bi 2.15 WO6 photocatalytic coating 102 is composed of Bi 2.15 WO6 photocatalytic coating is cured; among them, Bi 2.15 WO6 photocatalytic coating includes 1~5% Bi 2.15WO6 photocatalyst, and slurry, the slurry comprises water-based resin, curing agent and solvent, and the solvent is selected from any one of water, ethanol or anhydrous ethanol.

[0033] Specifically, Bi 2.15 WO6 photocatalyst is prepared by mixing sodium tungstate and bismuth nitrate in a molar ratio of bismuth to tungsten of 2.15 through hydrothermal reaction. More specifically, sodium tungstate dihydrate (Na2WO4·2H2O, ≥99.5%) and bismuth nitrate pentahydrate (Bi(NO3)3·5H2O, ≥99.0%) are used as raw materials to prepare Bi 2.15 The WO6 photocatalyst comprises: adding bismuth nitrate solution dropwise to sodium tungstate solution at a molar ratio of bismuth to tungsten of 2.15, mixing to obtain a milky white suspension, and adjusting the pH of the suspension to 1. Then, the suspension is added to a hydrothermal reactor, and a hydrothermal reaction is carried out at 180-200°C for 20-30 hours, and Bi is obtained after washing and drying. 2.15 WO6 photocatalyst. For example: a mixed solution of 5.21g Bi(NO3)3·5H2O and 100mL 1.0M HNO3, Bi(NO3)3, is added dropwise to a mixed solution of 1.65g Na2WO4·2H2O and 100mL NaOH, Na2WO4, at a molar ratio of Bi / W=2.15, and a milky suspension is obtained after mixing, wherein the mixing process is completed under magnetic stirring. Subsequently, the milky suspension is stirred at room temperature in the dark for 30 minutes, and the pH value of the suspension is adjusted to 1.0; the suspension is added to a stainless steel hydrothermal reactor, sealed, and placed in an oven at 180°C for reaction for 24 hours; the collected light yellow solid is repeatedly washed with anhydrous ethanol and deionized water, and dried in an oven at 80°C to obtain Bi 2.15 WO6 solid powder.

[0034] Figure 3 Bi in the embodiment of the present invention 2.15 SEM image of WO6 photocatalyst, where a is Bi 2.15 SEM image of WO6 photocatalyst, b is Bi in a 2.15 Locally enlarged SEM image of WO6 photocatalyst.

[0035] like Figure 3 As shown, the prepared Bi 2.15 WO6 photocatalyst has a flower-like structure assembled from layered nanosheets, which has higher activity under ultraviolet light.

[0036] Specifically, using Bi 2.15 WO6 photocatalyst prepared Bi 2.15 WO6 photocatalytic coating includes: mixing water-based resin and curing agent in a ratio of 4-5:1, and adding 1-5% Bi2.15 WO6 photocatalyst is mixed, and after mixing evenly, it is poured into the solvent and stirred evenly to obtain Bi 2.15 WO6 photocatalytic coating, wherein the water-based resin may be a water-based epoxy resin, such as EPICLON H-502-42W, purchased from DIS Corporation of Japan; and the curing agent may be EP39, purchased from Huntsman Corporation of Germany.

[0037] According to an embodiment of the present invention, Bi is coated on the inner wall of the cavity 101 of the gas phase sterilization reactor 1. 2.15 WO6 photocatalytic coating, Bi 2.15 WO6 photocatalytic coating is cured to form Bi 2.15 WO6 photocatalytic coating 102, wherein the inner wall of the cavity 101 of the gas phase sterilization reactor 1 is the inner wall of the air duct of an air purifier or air conditioner, and the material of the air duct can be Q235 steel plate. For example, a spray gun is used to spray Bi 2.15 WO6 photocatalytic coating was sprayed on Q235 steel plate and then cured at 40℃ for 3h to obtain Bi with smooth surface and dense 2.15 WO6 photocatalytic coating 102.

[0038] According to an embodiment of the present invention, the relative humidity of the air is 30% to 90%. Within this relative humidity range, the bioaerosol with a certain humidity enters the gas phase sterilization reactor 1, and the ultraviolet light irradiates the bioaerosol. 2.15 Active substances are generated in situ on the WO6 photocatalytic coating 102, and the active substances are in situ catalyzed with the moisture in the gas phase sterilization reactor 1 to produce oxidizing hydrogen peroxide to kill the bacteria in the bioaerosol in the gas phase sterilization reactor 1, wherein the active substances generated in situ are ≡Bi-OO•superoxyl radicals and / or ≡Bi-OOH peroxyl radicals.

[0039] Figure 4 Schematic diagram of the gas phase sterilization principle of the bismuth tungstate photocatalytic coating coupled with the three-dimensional fiber filter material in an embodiment of the present invention.

[0040] like Figure 4 As shown, under ultraviolet light, Bi 2.15 The WO6 photocatalytic coating generates electron-hole pairs, and the electrons react with the adsorbed Bi 2.15 The oxygen (O2) molecules on the surface of the WO6 photocatalytic coating react to generate highly oxidizing superoxide radicals (O2 ·- ), the superoxide radical combines with Bi in the photocatalytic coating to form ≡Bi-OO•superoxide radical and / or ≡Bi-OOH peroxide radical (i.e., active species), and the ≡Bi-OOH peroxide radical reacts with a hydrogen donor (i.e., water or hydrogen (H2O / H2) in the air) to form Bi-(H2O2) adAn intermediate, which is unstable, is converted in situ to form hydrogen peroxide (H2O2). Hydrogen peroxide decomposes into hydroxyl radicals (·OH) with stronger oxidizing properties under ultraviolet light irradiation, so that the oxidizing hydrogen peroxide and hydroxyl radicals are used to kill bacteria in bioaerosols. The three-dimensional fiber filter material with a tree-like structure can not only intercept bioaerosols with larger particle sizes, but also capture and disperse hydrogen peroxide and hydroxyl radicals; the tree-like structure and thickness of the three-dimensional fiber filter material are used to extend the ultraviolet light irradiation time and the continuous action time of hydrogen peroxide and hydroxyl radicals, thereby improving the killing efficiency of bioaerosols. Therefore, the present invention couples Bi 2.15 The chemical sterilization working mechanism of WO6 photocatalytic reaction and synergistic ultraviolet light can effectively kill bacteria and provide an effective technical solution for air purification and sterilization.

[0041] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments and drawings. The drugs or reagents used can all be purchased.

[0042] Example 1

[0043] Use Figure 1 The attached drawings show a dynamic gas phase sterilization efficiency evaluation system including a gas phase sterilization reactor, so as to evaluate the gas phase sterilization effect of the gas phase sterilization reactor and the gas phase sterilization method in the embodiments of the present invention.

[0044] Specifically, Figure 1 As shown, the system includes a first air pump 2 for compressing air, a second air pump 5 for compressing air, a purification device 3 for purifying air, a bioaerosol generator 4 for converting liquid bacterial liquid into gaseous bioaerosol, a flow control valve 6, a mixing tank 7 for mixing air and bioaerosol, a gas phase sterilization reactor 1 for gas phase sterilization, a collection bottle 8 (AGI-30) for collecting bacteria, and a sampling pump 9 at the end, wherein the first branch: the first air pump 2 is connected to the purification device 3, the bioaerosol generator 4 and the mixing tank 7 in sequence to pass the compressed air into the purification device 3 for purification, and the purified compressed air enters the bioaerosol generator 4 containing liquid bacterial liquid, and the liquid bacterial liquid is converted into bioaerosol by using the nozzle in the bioaerosol generator 4. The second branch: the second air pump 5 is connected to the flow control valve 6 with an adjustable flow rate to control the flow rate of air or the relative humidity of air. The mixing tank 7 fully mixes the air of the first and second branches and then introduces them into the gas phase sterilization reactor 1. Through the cooperation of the above two branches, the flow rate of the bioaerosol entering the gas phase sterilization reactor 1 is jointly controlled to ensure that there is no influence of other impurities. Finally, at the rear end of the gas phase sterilization reactor 1, the collection bottle 8 and the sampling pump 9 are connected to analyze the sterilization efficiency of the gas phase sterilization reactor 1.

[0045] The gas phase sterilization reactor 1 comprises: a cavity 101 defining the internal space of the gas phase sterilization reactor 1; a Bi 2.15 WO6 photocatalytic coating 102, a three-dimensional fiber filter material 103 fixed on the inner wall of the cavity 101 and covering the entire cross-section of the cavity 101, the three-dimensional fiber filter material 103 having a tree-like structure distributed along the air flow direction; and a three-dimensional fiber filter material 103 distributed in the cavity 101 for transmitting Bi 2.15 The WO6 photocatalytic coating 102 provides an ultraviolet light source 104 for ultraviolet light irradiation. The ultraviolet light source 104 penetrates the three-dimensional fiber filter material 103 and interacts with the Bi 2.15 WO6 photocatalytic coating 102 is parallel. Specifically, the size of the gas phase sterilization reactor 1 is 430cm×130cm×100cm; the ultraviolet light source 104 adopts a 254nm H-type mercury lamp, the thickness of the three-dimensional fiber filter material 103 is 20nm, and the light transmittance of the ultraviolet light source 104 penetrating the three-dimensional fiber filter material 103 reaches more than 30%, so that when the bacteria in the bioaerosol enters the interior of the three-dimensional fiber filter material 103, the ultraviolet light penetrates the three-dimensional fiber filter material 103 to sterilize the bacteria trapped in the three-dimensional fiber filter material 103.

[0046] Preparation of Bi 2.15 The WO6 photocatalytic coating 102 comprises: a water-based epoxy resin and a curing agent (EP39) are fully mixed in a stirrer at a ratio of 4.5:1, water is selected as a solvent, and 2% Bi is added. 2.15 WO6 photocatalyst is mixed and stirred evenly to obtain Bi 2.15 WO6 photocatalytic coating, in which Bi 2.15 WO6 photocatalyst is prepared by mixing sodium tungstate and bismuth nitrate in a molar ratio of bismuth to tungsten of 2.15. 2.15 The WO6 photocatalyst has a flower-like structure assembled from layered nanosheets, with a particle size of 3-4 µm. The thin sheet structure is conducive to improving the charge separation efficiency of the photocatalyst. Subsequently, the inner wall of the steel plate of the cavity 101 of the gas phase sterilization reactor 1 is polished with sandpaper to remove the rust on the inner wall surface of the steel plate, and the inner wall surface of the steel plate is rinsed with deionized water and anhydrous ethanol. After drying, the prepared Bi 2.15 WO6 photocatalytic coating was sprayed onto the inner wall of the steel plate and cured at room temperature to obtain a smooth Bi 2.15 WO6 photocatalytic coating 102, wherein the pressure of the spray gun during the spraying process is 0.3~0.4MPa.

[0047] Preparation of bioaerosol containing bacteria: The bacterial suspension is atomized into a bioaerosol containing bacteria by a bioaerosol generator 4, wherein the spray pressure in the bioaerosol generator 4 is controlled at 0.3 MPa and the flow rate is 0.6 mL / min, thereby obtaining a bioaerosol with a particle size uniformly distributed between 1.0 and 5.0 μm. The bacteria include Gram-negative bacteria Escherichia coli (E. coli, ATCC 25922) and Gram-positive bacteria Staphylococcus aureus (S. aureus, ATCC6538), and the bacterial liquid culture concentration is 10 8 ~10 9 CFU / mL. Subsequently, the obtained bioaerosol was mixed evenly with air in a mixing tank 7, and then entered into a gas phase sterilization reactor 1 for gas phase sterilization, so as to evaluate the gas phase sterilization efficiency of ultraviolet irradiation, synergistic photocatalytic reaction coupled with three-dimensional fiber filter material 103 filtration, wherein the relative humidity of the air was 60%.

[0048] The vapor phase sterilization reactor 1 is used for vapor phase sterilization method (abbreviated as UV / Bi 2.15 WO6 / 3D sterilization system) includes: under ultraviolet light, Bi coated on the inner wall of the cavity 101 2.15 The WO6 photocatalytic coating 102 generates active substances in situ, and the active substances react with the moisture in the air of the gas phase sterilization reactor 1 in situ to catalyze the generated hydrogen peroxide. The generated hydrogen peroxide is captured by the three-dimensional fiber filter material (abbreviated as 3D) 103 having a tree-like structure distributed along the air flow direction and dispersed on the tree-like structure surface of the three-dimensional fiber filter material 103, thereby utilizing ultraviolet light irradiation, Bi 2.15 The photocatalytic reaction of the WO6 photocatalytic coating 102 is coupled with the filtration of the three-dimensional fiber filter material 103 to achieve gas phase sterilization. After the gas phase sterilization reaction is completed, the air sample is collected by the collection bottle 8 for 10 minutes to evaluate the gas phase sterilization effect. At the same time, the sampling pump 9 is used to collect hydrogen peroxide (H2O2) in the gas phase and the N, N-diethyl-p-phenyl diammonium sulfate (DPD) method is used to measure the H2O2 concentration generated in the air.

[0049] In the collection bottle 8, 30 mL of phosphate-buffered saline (PBS) buffer (pH = 7.3 ± 0.2) was used to collect the sample for 10 min. The number of colonies formed (CFU) on each nutrient agar plate was calculated by the plate spreading method to calculate the number of bacteria in the collected PBS buffer, and then the logarithmic sterilization efficiency of the photocatalytic vapor phase sterilization reactor 1 was calculated (the specific test results are shown in Figure 5 The specific logarithmic sterilization efficiency calculation formula is shown in formula (1). The sterilization performance E is the logarithmic order of the reduction in bacterial concentration after sterilization, that is, the blank logarithmic concentration N0 (CFU / m 3 ) and through export of bacterial N t (CFU / m 3) logarithmic concentration ratio, calculated as formula (2).

[0050] (1).

[0051] (2).

[0052] Where N is the sample concentration of bioaerosol, CFU / m 3 ; r is the dilution factor of the plate coating; 0.1 is the volume of the sample taken each time, mL; s is the sampling flow rate, L / min; t is the sampling time.

[0053] Detection of the amount of H2O2 produced during gas phase sterilization: The N,N-diethyl-p-phenyl diammonium sulfate (DPD) method was used, and the absorbance was measured using a UV-visible spectrophotometer to determine the amount of H2O2 produced during the sterilization reaction.

[0054] Comparative Example 1: Sterilization system using UV

[0055] Comparative Example 1 used the same method as in Example 1 (abbreviated as UV / Bi 2.15 WO6 / 3D sterilization system) for gas phase sterilization, the only difference is that the gas phase sterilization reactor is only equipped with ultraviolet lamp (UV) and no Bi 2.15 WO6 photocatalytic coating, three-dimensional fiber filter material, and other reaction conditions were the same. Gas phase sterilization experiments were carried out on E. coli and S. aureus. The specific test results are as follows Figure 5 shown.

[0056] Comparative Example 2: Sterilization system using UV / TiO2

[0057] Comparative Example 2 uses the same system as Example 1 for gas phase sterilization, the only difference being that only an ultraviolet lamp and a titanium dioxide photocatalytic coating (UV / TiO2) are provided in the gas phase sterilization reactor, and no three-dimensional fiber filter material is provided. The other reaction conditions are the same, and gas phase sterilization experiments are carried out on E. coli and S. aureus. The method for forming the TiO2 photocatalytic coating is the same as that in Example 1. 2.15 The formation method of WO6 photocatalytic coating is the same, and the specific test results are as follows Figure 5 shown.

[0058] Comparative Example 3: Sterilization system using UV / H2O2

[0059] Comparative Example 3 uses the same system as Example 1 for gas phase sterilization, the only difference is that an ultraviolet lamp (UV) is set in the gas phase sterilization reactor, and 10μM H2O2 (UV / H2O2) is coated in the gas phase sterilization reactor. The other reaction conditions are the same. Gas phase sterilization experiments are carried out on E. coli and S. aureus. The specific test results are shown in Figure 5 shown.

[0060] Comparative Example 4: Using 3D Sterilization System

[0061] Comparative Example 4 uses the same system as Example 1 for gas phase sterilization, the only difference being that only a three-dimensional fiber filter (3D) is provided in the gas phase sterilization reactor, and the other reaction conditions are the same. Gas phase sterilization experiments are carried out on E. coli and S. aureus. The specific test results are shown in FIG. Figure 5 shown.

[0062] Comparative Example 5: Sterilization system using UV / 3D

[0063] Comparative Example 5 uses the same system as Example 1 for gas phase sterilization, the only difference being that only three-dimensional fiber filter material and ultraviolet lamp (UV / 3D) are provided in the gas phase sterilization reactor, and the other reaction conditions are the same. Gas phase sterilization experiments are carried out on E. coli and S. aureus. The specific test results are shown in FIG. Figure 5 shown.

[0064] Comparative Example 6: Sterilization system using UV / TiO2 / 3D

[0065] Comparative Example 6 uses the same system as Example 1 for gas phase sterilization, the only difference is that only three-dimensional fiber filter material, ultraviolet lamp and TiO2 photocatalytic coating (UV / TiO2 / 3D) are set in the gas phase sterilization reactor, and the other reaction conditions are the same. Gas phase sterilization experiments are carried out on E. coli and S. aureus. The specific test results are shown in the figure. Figure 5 shown.

[0066] Comparative Example 7: Using UV / Bi 2.15 WO6 Sterilization System

[0067] Comparative Example 7 uses the same system as Example 1 for gas phase sterilization, the only difference is that only ultraviolet lamps and Bi are set in the gas phase sterilization reactor. 2.15 WO6 photocatalytic coating (UV / Bi 2.15 WO6), the other reaction conditions were the same, and the gas phase sterilization experiment was carried out on E. coli and S. aureus. The specific test results are as follows Figure 5 shown.

[0068] Figure 5These are logarithmic sterilization efficiency graphs of the Gram-negative bacteria Escherichia coli (E. coli) and the Gram-positive bacteria Staphylococcus aureus (S. aureus) in Example 1 of the present invention and Comparative Examples 1-7, wherein a is the logarithmic sterilization efficiency graph of E. coli under ultraviolet light and ultraviolet photocatalytic reaction conditions; b is the logarithmic sterilization efficiency graph of E. coli under ultraviolet light, ultraviolet photocatalytic reaction coupled with three-dimensional fiber filter material filtration conditions; c is the logarithmic sterilization efficiency graph of S. aureus under ultraviolet light and ultraviolet photocatalytic reaction conditions; d is the logarithmic sterilization efficiency graph of S. aureus under ultraviolet light, ultraviolet photocatalytic reaction coupled with three-dimensional fiber filter material filtration conditions.

[0069] like Figure 5 As shown in the figure, when the residence time (i.e. reaction time) of E. coli and S. aureus in the gas phase sterilization reactor is 12.9s, under UV / Bi 2.15 In the WO6 / 3D sterilization system, the logarithmic sterilization efficiency can reach 4.25 and 3.77. In comparison, in the sterilization system using only UV, the logarithmic sterilization efficiency of E.coli is 2.74, and the logarithmic sterilization efficiency of S.aureus is 1.72. In the sterilization system using only 3D, the logarithmic sterilization efficiency of E.coli is 0.50, and the logarithmic sterilization efficiency of S.aureus is 0.50. In the sterilization system using UV / 3D, the logarithmic sterilization efficiency of E.coli is 3.02, and the logarithmic sterilization efficiency of S.aureus is 2.05. In the sterilization system using UV / TiO2, the logarithmic sterilization efficiency of E.coli is 2.96, and the logarithmic sterilization efficiency of S.aureus is 2.15. In the sterilization system using UV / TiO2 / 3D, the logarithmic sterilization efficiency of E. coli is 3.40, and the logarithmic sterilization efficiency of S. aureus is 2.53. In the sterilization system using UV / H2O2, the logarithmic sterilization efficiency of E. coli is 3.13, and the logarithmic sterilization efficiency of S. aureus is 2.75. 2.15 In the WO6 sterilization system, the logarithmic sterilization efficiency of E. coli is 3.82, and the logarithmic sterilization efficiency of S. aureus is 3.07. 2.15 The catalytic activity of the WO6 coating is superior to that of the commercial TiO2 photocatalytic coating, and the auxiliary effect of the three-dimensional fiber filter material also significantly improves the sterilization efficiency. In addition, during the test, it was found that the bacteria sterilized by ultraviolet light alone showed self-repair ability and formed colonies after 72 hours of incubation, while the bacteria sterilized by UV / Bi 2.15 After the bacteria sterilized by WO6 photocatalytic coating were incubated for the same time, no colonies appeared, indicating that UV light only reduced the culturability of bacteria and put the bacteria in a repairable state.

[0070] Therefore, the above examples and comparative examples prove that the self-doped Bi 2.15 The method of coupling the photocatalytic reaction of WO6 photocatalytic coating with three-dimensional fiber filter material can effectively kill bacteria in the air, improve indoor air quality and prevent respiratory infectious diseases.

[0071] Example 2

[0072] Compare 2.15 The stability of WO6 photocatalytic coating coupled with three-dimensional fiber filter material was studied for 6 months at a relative humidity of 60%. The specific test results are as follows Figure 6 shown.

[0073] Figure 6 The stability test effect diagram of the gas phase sterilization reactor of Example 1 of the present invention and Comparative Example 7 on S. aureus is shown.

[0074] like Figure 6 As shown in the figure, when the residence time of S. aureus in the gas phase sterilization reactor is 3.6s, UV / Bi 2.15 WO6 and UV / Bi 2.15 The logarithmic sterilization efficiency of the WO6 / 3D sterilization system was 1.51 and 1.96 respectively; after 6 months of sterilization cycle, the UV / Bi 2.15 WO6 and UV / Bi 2.15 The logarithmic sterilization efficiency of WO6 / 3D sterilization system was 1.40 and 1.83 respectively. When the residence time of S. aureus in the gas phase sterilization reactor was 12.9s, UV / Bi 2.15 WO6 and UV / Bi 2.15 The logarithmic sterilization efficiency of the WO6 / 3D sterilization system was 3.07 and 3.77 respectively; after 6 months of sterilization cycle, the UV / Bi 2.15 WO6 and UV / Bi 2.15 The logarithmic sterilization efficiencies of the WO6 / 3D sterilization system were 2.95 and 3.60 respectively. 2.15 The WO6 photocatalytic coating still has high reactivity after long-term operation.

[0075] Further, the effect of H2O2 production on sterilization efficiency was investigated. Figure 7 shown.

[0076] Figure 7 The amount of H2O2 produced and the ultraviolet-visible light absorption spectrum of the present invention, wherein a is the UV / Bi 2.15 a is the UV-visible absorption spectrum of the amount of H2O2 produced over time under the WO6 sterilization system, and b is the linear relationship between the amount of H2O2 produced and the logarithmic sterilization efficiency.

[0077] like Figure 7 As shown in the figure, by detecting the H2O2 content in the samples under different working conditions, it was found that the absorbance of the UV-visible spectrophotometer gradually increased over time, indicating that H2O2 was continuously produced in the gas phase sterilization reactor. By analyzing the relationship between the amount of H2O2 produced and the logarithmic sterilization efficiency, the linear correlation coefficient (R 2 ) was 0.985, indicating that the logarithmic sterilization efficiency was closely related to the generation of H2O2.

[0078] In view of the importance of relative humidity in sterilization efficiency, the present invention also conducted a gas phase sterilization experiment involving H2O2 concentration detection under relative humidity conditions of 35% and 60% (the test time was 10 minutes). The specific test results are as follows: Figure 8 shown.

[0079] Figure 8 Graphs showing the production of H2O2 and the logarithmic sterilization efficiency at different relative humidities of the present invention, wherein a is a graph showing the production of H2O2 at different relative humidities, and b is a graph showing the logarithmic sterilization efficiency of S. aureus at different relative humidities.

[0080] like Figure 8 As shown, when the relative humidity is 35%, UV, UV / Bi 2.15 The concentration of H2O2 produced by WO6 is 1.60mg / m 3 and 2.73 mg / m 3 In contrast, at a relative humidity of 60%, UV, UV / Bi 2.15 The concentration of H2O2 produced by WO6 is 2.04 mg / m 3 , 3.80 mg / m 3 , indicating that with the increase of relative humidity, the production of H2O2 increases, and the H2O in the air is the hydrogen donor for the in-situ production of H2O2. Compared with the logarithmic sterilization efficiency at a relative humidity of 35%, the relative humidity of 60% and the use of UV, UV / Bi alone 2.15 The corresponding logarithmic sterilization efficiencies of S. aureus increased by 9.4%, 15.0%, and 9.8% when treated with WO6 and UV / TiO2, respectively, indicating that increasing relative humidity can improve the sterilization efficiency.

[0081] Furthermore, in order to explore 2.15 The mechanism of in-situ generation of H2O2 on the WO6 surface was analyzed by Raman analysis under UV light. Fig. 9 shown.

[0082] Fig. 9 In the embodiment of the present invention, Bi2WO6 and Bi 2.15Raman spectrum of WO6 under ultraviolet light.

[0083] like Fig. 9 As shown in the Raman spectrum, 301cm -1 The vibration peak at Bi 3+ and WO6 6- Translational movement. 2.15 WO6 at 793cm -1 and 822cm -1 The absorption peak at 901 cm is related to the OWO bond in the WO6 octahedron. -1 A new absorption peak appears at 2.15 OO vibration of peroxide species formed on the surface of WO6. 3+ and WO6 6- The characteristic peak related to translational motion is from 301cm -1 Offset to 305cm -1 , while the OWO group is at 793 cm -1 and 822cm -1 There is no shift at 901 cm -1 The OO bond formed at 2.15 ≡Bi-OO•superoxide radical or ≡Bi-OOH peroxide radical at WO6. By obtaining hydrogen donor from H2O in the air, ≡Bi-OO•superoxide radical can be easily converted into ≡Bi-OOH peroxide radical, thereby promoting the in-situ generation of H2O2, which is similar to the aforementioned Figure 4 The mechanism in corresponds to .

[0084] In summary, the gas phase sterilization method and gas phase sterilization reactor provided by the present invention are feasible and have high sterilization efficiency. The gas phase sterilization reactor mentioned in the present invention is suitable for various places (such as factories, indoor buildings, etc.) where air sterilization is required. During the application process, the gas phase sterilization reaction device is installed at the air outlet of the air conditioner, purifier and fan coil unit, etc.

[0085] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A gas phase sterilization method of bismuth tungstate photocatalytic coating coupled with three-dimensional fiber filter material, characterized in that: The gas phase sterilization method adopts a gas phase sterilization reactor, which is installed at the air outlet of the air conditioner, purifier and fan coil unit. The gas phase sterilization reactor includes: a cavity defining the internal space of the gas phase sterilization reactor; Bi coated on the inner wall of the cavity 2.15 WO6 photocatalytic coating, a three-dimensional fiber filter material fixed on the inner wall of the cavity and covering the entire cross-section of the cavity, the three-dimensional fiber filter material having a tree-like structure distributed along the air flow direction; and distributed in the cavity and used to provide the Bi 2.15 The WO6 photocatalytic coating provides a UV light source for UV irradiation; The gas phase sterilization method comprises: Under ultraviolet light, Bi coated on the inner wall of the cavity 2.15 The WO6 photocatalytic coating generates active substances in situ, and the active substances react with the moisture in the air of the gas phase sterilization reactor in situ to catalyze the generated hydrogen peroxide, which is captured by the three-dimensional fiber filter material with a tree-like structure distributed along the air flow direction and dispersed on the surface of the tree-like structure of the three-dimensional fiber filter material, thereby utilizing the ultraviolet light irradiation, Bi 2.15 The photocatalytic reaction of the WO6 photocatalytic coating is coupled with the three-dimensional fiber filter material filtration to achieve gas phase sterilization; The inner wall of the gas phase sterilization reactor cavity is the inner wall of the air duct, and the ultraviolet light source penetrates the three-dimensional fiber filter material and is parallel to the inner wall of the gas phase sterilization reactor and Bi 2.15 WO6 photocatalytic coating.

2. The gas phase sterilization method according to claim 1, characterized in that: The fibers constituting the tree-like structure of the three-dimensional fiber filter material have a diameter of 44.4±10.2 μm; The three-dimensional fiber filter material has a thickness of 3.0-20.0 mm, a porosity of 90-95%, and a mass per unit area of ​​200-260 g / m 2 ; The material of the three-dimensional fiber filter material is selected from polyethylene terephthalate.

3. The gas phase sterilization method according to claim 1, characterized in that: The Bi 2.15 WO6 photocatalytic coating is composed of Bi 2.15 WO6 photocatalytic coating is cured; Among them, the Bi 2.15 WO6 photocatalytic coating includes Bi 2.15 WO6 photocatalyst, and slurry, wherein the slurry comprises a water-based resin, a curing agent and a solvent, and the solvent is selected from any one of water, ethanol or anhydrous ethanol.

4. The gas phase sterilization method according to claim 3, characterized in that: The Bi 2.15 The WO6 photocatalyst has a flower-like structure assembled from layered nanosheets. 2.15 The loading amount of WO6 photocatalyst is 1~5%; Among them, the Bi 2.15 The WO6 photocatalyst is obtained by mixing sodium tungstate and bismuth nitrate in a molar ratio of bismuth to tungsten of 2.15 through a hydrothermal reaction.

5. The gas phase sterilization method according to claim 1, characterized in that: The relative humidity of the air is 30% to 90%.

6. The gas phase sterilization method according to claim 1, characterized in that: The active substance is ≡Bi-OO•superoxyl radical and / or ≡Bi-OOH peroxyl radical.

7. The gas phase sterilization method according to claim 1, characterized in that: There are one or more three-dimensional fiber filter materials, and the three-dimensional fiber filter materials are evenly spaced.

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