Virus adsorbents and composite materials

Abstract

To provide a virus adsorbent that can selectively adsorb viruses onto bacteria, and a composite material containing the virus adsorbent. [Solution] The material contains at least one selected from the group consisting of calcium phosphate and aluminum oxide, has a zeta potential of 38 mV or less, and a BET specific surface area of ​​220 m². 2 A virus adsorbent with a concentration of less than / g. A composite material containing the virus adsorbent and a photocatalyst.

Description

【Technical Field】 【0001】 The present invention relates to a virus adsorbent and a composite material. 【Background Art】 【0002】 Conventionally, since bacteria and viruses present in water or air have an adverse effect on the health of humans and animals, bacteria and viruses have been removed to purify water and air. For example, Patent Document 1 describes a microorganism adsorbent characterized by using volcanic ash soil in which Al2O3 is 30 wt% or more as a microorganism adsorbent capable of adsorbing and sterilizing microorganisms such as bacteria and viruses. 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 International Publication No. 2020 / 045580 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 Conventionally, the adsorption of bacteria, which are highly likely to directly affect the health of humans and animals, has been emphasized. However, in some cases, such as when removing viruses such as avian influenza in the air in a chicken coop, it is required to preferentially remove viruses rather than bacteria. However, the adsorption of viruses competes with the adsorption of coexisting bacteria. When the adsorption sites of the adsorbent are occupied by bacteria, the adsorption efficiency of viruses decreases. Therefore, it is necessary to selectively adsorb viruses rather than bacteria. 【0005】 <� Therefore, an aspect of the present invention aims to provide a virus adsorbent capable of selectively adsorbing viruses with respect to bacteria and a composite material containing the virus adsorbent. 【Means for Solving the Problems】 【0006】 One aspect of the present disclosure includes, for example, the following [1] to [8]. [1] Containing at least one selected from the group consisting of calcium phosphate and aluminum oxide, having a zeta potential of 38 mV or less, and a BET specific surface area of 220 m 2 / g or less, a virus adsorbent. [2] The virus adsorbent according to [1], wherein the calcium phosphate is tricalcium phosphate. [3] The virus adsorbent according to [1] or [2], wherein the zeta potential is -20 mV or more. [4] The virus adsorbent according to any one of [1] to [3], wherein the BET specific surface area is 80 m 2 / g or less. [5] The virus adsorbent according to any one of [1] to [4], having an average particle size of 11 μm or less. [6] The virus adsorbent according to any one of [1] to [5], having a BET average pore diameter of 10 nm or more. [7] The virus adsorbent according to any one of [1] to [6], having a bulk density of 1.5 g / cm 3 or less. [8] A composite material comprising the virus adsorbent according to any one of [1] to [7] and a photocatalyst. 【Advantages of the Invention】 【0007】 According to one aspect of the present invention, a virus adsorbent capable of selectively adsorbing a virus to bacteria and a composite material containing the virus adsorbent can be provided. 【Modes for Carrying Out the Invention】 【0008】 Hereinafter, embodiments of the present disclosure will be described in detail. 【0009】 In this specification, numerical ranges indicated using "~" represent a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. "A or greater" in a numerical range means A and the range exceeding A. "A or less" in a numerical range means A and the range less than A. In numerical ranges described stepwise in this specification, the upper or lower limit of a numerical range in one step can be arbitrarily combined with the upper or lower limit of a numerical range in another step. In numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with the values ​​shown in the examples. "A or B" means that either A or B is included, or both are included. Unless otherwise specified, the materials exemplified in this specification can be used individually or in combination of two or more. The content of each component in the adsorbent means the total amount of multiple substances present in the adsorbent when there are multiple substances corresponding to each component, unless otherwise specified. The term "process" includes not only independent processes, but also any process that cannot be clearly distinguished from other processes, as long as its intended function is achieved. 【0010】 <Virus adsorbent> A virus adsorbent according to one embodiment comprises at least one selected from the group consisting of calcium phosphate and aluminum oxide, has a zeta potential of 38 mV or less, and a BET specific surface area of ​​220 m². 2 The amount is less than / g. The virus adsorbent can also be called an adsorbent for virus adsorption. By including at least one selected from the group consisting of calcium phosphate and aluminum oxide, the virus adsorbent exhibits excellent adsorption properties to viruses, and by having a zeta potential and BET specific surface area within a specific range, it becomes possible to selectively adsorb viruses to bacteria. The inventors of this application surmise the following reason. 【0011】 In other words, when the virus adsorbent contains at least one selected from the group consisting of calcium phosphate and aluminum oxide, calcium phosphate and aluminum oxide have excellent chemical adsorption properties, and therefore exhibit superior adsorption to viruses. Furthermore, since viruses tend to have a positive surface potential, a relatively small zeta potential of the virus adsorbent suppresses electrostatic repulsion between the virus and the virus adsorbent, making it easier for the virus to be selectively adsorbed onto bacteria. Also, since bacteria are larger than viruses, a larger specific surface area of ​​the virus adsorbent leads to selective adsorption of bacteria. Therefore, a relatively small specific surface area of ​​the virus adsorbent suppresses bacterial adsorption, making it easier for the virus to be selectively adsorbed onto bacteria. For these reasons, a virus adsorbent containing at least one selected from the group consisting of calcium phosphate and aluminum oxide, having a relatively small zeta potential, and having a relatively small BET specific surface area can selectively adsorb viruses onto bacteria. However, the reasons why the present invention is effective are not limited to the reasons stated above. 【0012】 Examples of calcium phosphate include tricalcium phosphate, monocalcium phosphate, dicalcium phosphate, tetracalcium phosphate, octacalcium phosphate, calcium hydroxide phosphate, fluorine apatite, chlorine apatite, carbonate apatite, wittrockite, and their hydrates. Calcium phosphate may also be amorphous calcium phosphate. Tricalcium phosphate may also be used, from the viewpoint of more selectively adsorbing viruses. Tricalcium phosphate may be monoclinic α-tricalcium phosphate, hexagonal α'-tricalcium phosphate, or β-tricalcium phosphate. 【0013】 The calcium phosphate content in the virus adsorbent may be 50% or more by mass, 70% or more by mass, 90% or more by mass, 95% or more by mass, or 100% by mass (in a configuration where the virus adsorbent is substantially composed of calcium phosphate), based on the total mass of the virus adsorbent, from the viewpoint of enabling more selective adsorption of viruses. If the calcium phosphate is tricalcium phosphate, the tricalcium phosphate content in the virus adsorbent may be within the above ranges based on the total mass of the virus adsorbent, from the viewpoint of enabling more selective adsorption of viruses. 【0014】 From the viewpoint of being able to more selectively adsorb viruses, aluminum oxide may be α-alumina or γ-alumina. Compared to α-alumina, γ-alumina tends to have a larger BET specific surface area and a lower bulk density. 【0015】 The aluminum oxide content in the virus adsorbent may be 50% by mass or more, 70% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass (in a configuration where the virus adsorbent is substantially composed of aluminum oxide), based on the total mass of the virus adsorbent, from the viewpoint of more selectively adsorbing viruses. If the aluminum oxide is α-alumina, the α-alumina content in the virus adsorbent may be within the above range, based on the total mass of the virus adsorbent, from the viewpoint of more selectively adsorbing viruses. If the aluminum oxide is γ-alumina, the γ-alumina content in the virus adsorbent may be within the above range, based on the total mass of the virus adsorbent, from the viewpoint of more selectively adsorbing viruses. 【0016】 The shape of the virus adsorbent is not particularly limited. Examples of virus adsorbent shapes include spherical, nearly spherical, ellipsoidal, nearly ellipsoidal, hemispherical, nearly hemispherical, rectangular parallelepiped, and nearly rectangular parallelepiped. 【0017】 The zeta potential of the virus adsorbent is 38 mV or less. The zeta potential of the virus adsorbent can be adjusted, for example, by changing the drying conditions when manufacturing the virus adsorbent, surface-treating the virus adsorbent, or the like. In this specification, the zeta potential means a value measured by the method described in the examples below. 【0018】 From the viewpoint of being able to adsorb viruses more selectively, the zeta potential of the virus adsorbent may be 36 mV or less, 34 mV or less, or 32 mV or less. The zeta potential of the virus adsorbent may be 30 mV or less, 28 mV or less, 26 mV or less, or 25 mV or less. From the viewpoint of being able to adsorb viruses more selectively, the zeta potential of the virus adsorbent may be -40 mV or more, -30 mV or more, -20 mV or more, or -10 mV or more. 【0019】 From the viewpoint of suppressing aggregation of virus adsorbents, the absolute value of the zeta potential of the virus adsorbent may be 3 mV or more, 5 mV or more, 7 mV or more, or 9 mV or more. From the viewpoint of suppressing repulsion between the virus adsorbent and the virus and being able to adsorb the virus more selectively, the absolute value of the zeta potential of the virus adsorbent may be 38 mV or less, 36 mV or less, 34 mV or less, or 32 mV or less. 【0020】 The BET specific surface area of the virus adsorbent is 220 m 2 / g or less. The BET specific surface area of the virus adsorbent can be adjusted, for example, by changing the firing conditions (e.g., firing temperature and firing time) when manufacturing the virus adsorbent, pulverizing the virus adsorbent to change the size of the virus adsorbent, or the like. In this specification, the BET specific surface area means a value measured by the method described in the examples below. 【0021】 From the viewpoint of being able to adsorb viruses more selectively, the BET specific surface area of the virus adsorbent is 200 m 2 / g or less, 180 m 2 / g or less, 150 m 2 / g or less, 120 m 2 / g or less, 100m 2 / g or less, 80m 2 / g or less, 60m 2 / g or less, 40m 2 / g or less, 30m 2 / g or less, 20m 2 / g or less, or 15m 2 It may be less than / g. The BET specific surface area of ​​the virus adsorbent is 0m² from the viewpoint that the amount of virus adsorbed per unit mass of the virus adsorbent increases as the number of adsorption sites increases. 2 / g, 5m 2 / g or more, 10m 2 / g or more, 15m 2 / g or more, 30m 2 / g or more, 50m 2 / g or more, 80m 2 / g or more, 100m 2 / g or more, or 150m 2 It may be more than / g. 【0022】 The average particle size of the virus adsorbent may be 20 μm or less, 15 μm or less, 11 μm or less, 8 μm or less, 6 μm or less, 5 μm or less, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, or 0.5 μm or less, from the viewpoint of suppressing aggregation of virus adsorbents among themselves and enabling more selective adsorption of viruses. The average particle size of the virus adsorbent may be 0.01 μm or more, 0.05 μm or more, or 0.1 μm or more, from the viewpoint of suppressing repulsion between the virus adsorbent and the virus and enabling more selective adsorption of viruses. The average particle size of the virus adsorbent can be measured by the method described in the examples below. 【0023】 The average BET pore diameter of the virus adsorbent may be 5 nm or more, 10 nm or more, 15 nm or more, 20 nm or more, 25 nm or more, or 30 nm or more, from the viewpoint of excellent adsorption to viruses. The average BET pore diameter of the virus adsorbent may be 100 nm or less, 50 nm or less, or 40 nm or less, from the viewpoint of suppressing bacterial adsorption and enabling more selective adsorption of viruses. The average BET pore diameter of the virus adsorbent can be adjusted, for example, by changing the firing conditions (e.g., firing temperature and firing time) when manufacturing the virus adsorbent, or by changing the size of the virus adsorbent by pulverizing it. The average BET pore diameter of the virus adsorbent can be measured by the method described in the examples below. 【0024】 The bulk density of the virus adsorbent is set at 3 g / cm³ from the perspective that increasing the pore volume increases the amount of virus removed per unit mass of the virus adsorbent. 3 Below, 2g / cm 3 Below 1.5g / cm 3 The following, or 1.3 g / cm³ 3 The following is also acceptable: The bulk density of the virus adsorbent should be 0.1 g / cm³ from the viewpoint of suppressing bacterial adsorption and enabling more selective adsorption of viruses. 3 More than 0.5g / cm 3 More than 1g / cm 3 Above, or 1.2 g / cm³ 3 The above is also acceptable. The bulk density of the virus adsorbent can be adjusted, for example, by changing the firing conditions (e.g., firing temperature and firing time) when manufacturing the virus adsorbent, or by changing the size of the virus adsorbent by crushing it. The bulk density of the virus adsorbent can be measured by the method described in the examples below. 【0025】 The Rsp value of the virus adsorbent (Rsp value corrected for BET specific surface area) is set to 0.10 m from the perspective that the higher the hydrophilicity of the virus adsorbent, the easier it is to selectively adsorb viruses compared to hydrophobic bacteria. -2 Above, 0.17m -2 More than 0.20m -2 More than 0.30m-2 Above, 0.40m -2 Above, or 0.50m -2 The Rsp value of the virus adsorbent should be 0.80 m, because if the hydrophilicity becomes too high, it will be difficult to adsorb viruses. -2 Below, 0.70m -2 The following, or 0.60m -2 The following may also be used. The Rsp value of the virus adsorbent can be adjusted by surface treatment or modification of the virus adsorbent with reactive reagents such as acids, alkalis, or silane coupling agents. The Rsp value of the virus adsorbent can be measured by the method described in the examples below. 【0026】 <Method for manufacturing virus adsorbent> As a method for producing calcium phosphate, which is one example of a virus adsorbent, known methods can be used. For example, it can be obtained by adding an aqueous solution of a calcium salt and ammonia water to an aqueous solution of disodium hydrogen phosphate (Na2HPO4), thoroughly washing the resulting white precipitate, and drying it. Also, as a method for producing aluminum oxide, which is another example of a virus adsorbent, known methods can be used. For example, bauxite is washed at 250°C with a hot solution of sodium hydroxide by the Bayer process, impurities are removed by filtration while the aluminum hydroxide remains dissolved, and the mixture is cooled. By heating this to 1050°C, the aluminum hydroxide is dehydrated and aluminum oxide is obtained. 【0027】 The zeta potential and BET specific surface area of ​​virus adsorbents (calcium phosphate, aluminum oxide) can be adjusted by known methods. For example, the particle size of the resulting virus adsorbent can be adjusted and the BET specific surface area adjusted by changing the conditions (temperature, reaction time, precursor concentration, etc.) during the production of the virus adsorbent. In addition, the zeta potential can be adjusted by surface treatment or modification of the virus adsorbent with reactive reagents such as acids, alkalis, and silane coupling agents. 【0028】 <Composite materials> The virus adsorbent described above may be combined with a photocatalyst to form a composite material. That is, another embodiment of the present invention is a composite material comprising the virus adsorbent described above and a photocatalyst. 【0029】 A known photocatalyst can be used. For example, titanium dioxide can be used as a photocatalyst. 【0030】 The composite material may contain materials other than the virus adsorbent and the photocatalyst. For example, the composite material may further contain a binder compound that connects the virus adsorbent and the photocatalyst. The binder compound may be, for example, a resin. 【0031】 The virus adsorbent or composite material described above may be installed, for example, on a membrane through which a fluid (gas, liquid) passes. More specifically, the virus adsorbent or composite material described above may be installed on a membrane installed at the air intake of a chicken coop in a poultry farm to capture viruses in the outside air and inactivate them. [Examples] 【0032】 The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples. 【0033】 [Preparation of virus adsorbent] (Examples 1-6, Comparative Example 1) Virus adsorbents having the parameters shown in Table 2 were prepared and left to stand for 120 hours under conditions of 23°C and 25% RH to thoroughly remove moisture from the virus adsorbents. 【0034】 [Measurement of Zeta Potential] To 0.5 g of virus adsorbent, 10 mL of distilled water was added, and the mixture was dispersed in an ultrasonic bath for 3 minutes as a pretreatment. After pretreatment, the sample aqueous solution was obtained by titration with hydrochloric acid or potassium hydroxide to a pH of 7. Next, the zeta potential of the sample aqueous solution was measured by zeta potential measurement using microscopy electrophoresis (measuring device: Kyowa Interface Science Co., Ltd., Zeta Potentiometer ZC-3000, light source: 660 nm red laser light source, scattered light, lens setting: ×10, measurement environment: 22°C, 53% RH). In microscopy electrophoresis, a DC voltage was applied to the sample aqueous solution packed in a glass cell to electrophores the virus adsorbent suspended between electrodes, and the moving virus adsorbent was observed and automatically tracked under a microscope, and the zeta potential was calculated from its electrophoretic velocity. The spacing between the glass cells is 1.0 mm wide. The first 20% of the 1.0 mm wide area (within 0.2 mm from one wall) and the last 20% of the area (within 0.2 mm from the other wall) are designated as stationary regions. For each stationary region, a total of 500 virus adsorbents were tracked to calculate their zeta potential. The average of the zeta potentials measured from the two stationary regions was used as the zeta potential of the virus adsorbent. The measurement results are shown in Table 2. 【0035】 [Measurement of BET specific surface area and BET average pore diameter] The BET specific surface area of ​​the virus adsorbent was measured using the BET method under the following conditions. The total pore volume was also calculated using the BET method (p / p0 = 0.98), and the average BET pore diameter was measured using the following formula. The measurement results are shown in Table 2. <Condition> Pretreatment method: Vacuum degassing was performed at 120°C for 16 hours using BELPREP-vac II (manufactured by Microtrac-Bel Corporation). Measurement method: Using BELSORP-max II (manufactured by Microtrac-Bel Co., Ltd.), nitrogen adsorption / desorption isotherms were obtained by the constant volume method. Adsorption temperature: 77.35K Adsorbent: Nitrogen Saturated vapor pressure: 101.38 kPa (measured) Adsorbate cross section: 0.162nm 2 (BET average pore diameter) = 4 × (total pore volume) / (BET specific surface area) 【0036】 [Measurement of average particle size] The virus adsorbent was dispersed in water, and the dispersion was filled into the flow cell of a particle size distribution analyzer LA-960 (manufactured by Horiba, Ltd.). The measurement sequence conditions shown in Table 1 were set, and the average particle size (volume basis) of the virus adsorbent was measured. The measurement results are shown in Table 2. Note that "-" in the table means that measurement was not performed. 【0037】 [Table 1] 【0038】 [Measurement of bulk density] Based on JIS R 9301-2-3, the virus adsorbent was gently placed into a 10 mL graduated cylinder using a spatula, and the bulk density was calculated from the mass of the 10 mL adsorbent. The measurement results are shown in Table 2. A "-" in the table indicates that the measurement was not performed. 【0039】 [Measurement of Rsp value] To 0.5 g of virus adsorbent, 10 mL of distilled water was added, followed by pretreatment using an ultrasonic bath for 3 minutes. The pretreated sample aqueous solution was then subjected to pulsed NMR spectroscopy (measurement device: Xigo nanotools, Acorn area, observed nucleus: 1 (H nucleus, measurement temperature: 25°C) Relaxation time T 2s The relaxation time T was measured for the sample aqueous solution without the virus adsorbent. 2b The measured T 2b and T 2sThe index Rsp value was calculated based on the following formula. A larger Rsp value indicates better affinity between the virus adsorbent and the solvent (water), or a larger contact area (interface area) between the virus adsorbent and the solvent. The measured result (index Rsp value) was corrected using the BET specific surface area of ​​the virus adsorbent. Table 2 shows the measured Rsp value after correction using the BET specific surface area of ​​the virus adsorbent. <Formula for calculating the Rsp index value> Index Rsp value = T 2b / T 2s -1 <Formula for calculating the specific surface area corrected Rsp value> Specific surface area correction Rsp(m -2 ) = Index Rsp value ÷ Total BET specific surface area of ​​particles added to 10 mL of solvent (m²) 2 )" 【0040】 [Evaluation of Δ adsorption rate] The virus adsorption rate and bacterial adsorption rate were measured using the following method, and the Δ adsorption rate was calculated from the difference between the virus adsorption rate and bacterial adsorption rate (virus adsorption rate - bacterial adsorption rate) in the evaluation of a 1 mg / mL concentration virus adsorbent. The results of the Δ adsorption rate calculation are shown in Table 2. A higher Δ adsorption rate indicates that the virus can be selectively adsorbed onto bacteria. 【0041】 <Evaluation of virus adsorption rate> The virus adsorption rate of the virus adsorbent was evaluated based on ASTM E1052 and JIS R 1756. Specifically, 5 mL of test solution was prepared using PBS (phosphate-buffered saline) with two concentrations of virus adsorbent powder: 0.2 mg / mL and 1 mg / mL, and a test phage solution (approximately 1 × 10⁻¹⁶) was used. 8 pfu / mL. 0.1 mL of the suspension in PBS was mixed and shaken at room temperature (23°C) at 120 rpm. After shaking for 5 minutes, centrifugation was performed at 5000 rpm for 20 seconds to settle the powder. 1 mL of the supernatant was taken and mixed with 9 mL of SCDLP to prepare the test solution. n=2 Test phage: Bacteriophage Φ6 (NBRC105899) (Host: Pseudomon as syringae (NBRC 14084)) The test solution was gradually diluted with PBS, and the phage infectivity titer was determined using formula (1). N = Z × DF × W·······(1) N: Infectious titer (pfu) Z: Average plaque count (pfu) in two petri dishes DF: Dilution ratio W: Volume of SCDLP medium used for washing (mL) The virus adsorption rate was determined from the obtained results using equation (2). (VI B -VI S ) / VI B ×100[%]·······(2) VI B : Average infectious titer (pfu / mL) of PBS phage fluid VI S : Average infectivity titer (pfu / mL) of the mixture with each powder 【0042】 <Evaluation of bacterial adsorption rate> The bacterial adsorption rate of the virus adsorbent was evaluated based on EN 1040:2005. Specifically, 5 mL of test solution was prepared using PBS (phosphate-buffered saline) with two concentrations of virus adsorbent powder: 0.2 mg / mL and 1 mg / mL, and a test bacterial solution (approximately 1 × 10⁻¹⁶) was used. 8 cfu / mL. 0.1 mL of the suspension in PBS was mixed and shaken at room temperature (23°C) at 120 rpm. After shaking for 5 minutes, centrifugation was performed at 5000 rpm for 20 seconds to settle the powder. 1 mL of the supernatant was taken and mixed with 9 mL of SCDLP to prepare the test solution. n=2 Test bacterium: Staphylococcus aureus (NBRC12732) The test solution was gradually diluted with PBS, and the number of viable bacteria was determined. Based on the obtained results, the bacterial adsorption rate was determined in the same manner as the viral adsorption rate. 【0043】 [Table 2]

Claims

[Claim 1] It comprises at least one selected from the group consisting of calcium phosphate and aluminum oxide, The zeta potential is 38 mV or less. BET specific surface area is 220 m² ２ A virus adsorbent with a concentration of less than / g. [Claim 2] The virus adsorbent according to claim 1, wherein the calcium phosphate is tricalcium phosphate. [Claim 3] The virus adsorbent according to claim 1, wherein the zeta potential is -20 mV or higher. [Claim 4] The BET specific surface area is 80 m². ２ The virus adsorbent according to claim 1, wherein the amount is less than or equal to / g. [Claim 5] The virus adsorbent according to claim 1, wherein the average particle size is 11 μm or less. [Claim 6] The virus adsorbent according to claim 1, wherein the average BET pore diameter is 10 nm or more. [Claim 7] Bulk density is 1.5 g / cm³ ３ The virus adsorbent according to claim 1, which is as follows: [Claim 8] A composite material comprising a virus adsorbent according to any one of claims 1 to 7 and a photocatalyst.