CN114931777A

CN114931777A - Removing device and removing method

Info

Publication number: CN114931777A
Application number: CN202210407480.8A
Authority: CN
Inventors: 藤岛昭; 益田秀树; 细田和夫
Original assignee: University of Shanghai for Science and Technology
Current assignee: University of Shanghai for Science and Technology
Priority date: 2021-04-13
Filing date: 2022-04-08
Publication date: 2022-08-23
Also published as: JP2022162667A

Abstract

The invention provides a removing device and a removing method, which enable the removing rate of target micro-substances such as bacteria and viruses in gas or liquid to be higher than that of the prior art. The removing device is provided with a gas or liquid flow channel and a porous film arranged in the flow channel, wherein the film is made of metal oxide, the average pore diameter of the film is more than 5nm and less than 1000nm, and the relative standard deviation of the pore diameter distribution of the fine pores is less than 10%.

Description

Removing device and removing method

Technical Field

The present invention relates to a removing device and a removing method.

Background

Various water and air purification techniques have been proposed so far, and recently, attention to influenza virus and new coronavirus has been increased, and related techniques for removing harmful substances in gas and liquid are receiving much attention.

For example, patent document 1 (Japanese patent laid-open No. 2017-124179) describes a method for removing viruses using a filter medium, which has a retrovirus Log Reduction Value (LRV) of more than about 6. The medium can be used to remove minute substances such as viruses from a liquid sample.

However, in the conventional technique, since the pore size of the filter medium is not uniform, the removal rate of bacteria or viruses (target minute substances) which are the target of removal is not high, and thus it is desired to improve. In the conventional art, the fine pores of the filter medium partially intercept fine substances other than the target fine substances or pass through the fine pores without intercepting the target fine substances.

Disclosure of Invention

For this reason, the present invention is intended to provide a removing apparatus that enables the removal rate of target minute substances such as bacteria and viruses in gas or liquid to be higher than that of the conventional art.

In order to solve the above problems, the removing device of the present invention has the following features: a flow channel provided with a gas or liquid, and a porous membrane disposed in the flow channel, the membrane being made of a metal oxide, having an average pore diameter of 5nm or more and 1000nm or less, and having a pore diameter distribution of pores having a relative standard deviation of less than 10%.

The invention can make the removal rate of target micro-substances such as bacteria and viruses in gas or liquid higher than that of the traditional technology.

Drawings

Fig. 1A is an SEM image of the thin film of example 1.

Fig. 1B is an SEM image of the thin film of comparative example 1.

Fig. 2 shows an example of pore size distribution of the thin films of example 1 and comparative example 1.

FIG. 3 is a reference graph of the relationship between the standard deviation and the cumulative probability in a normal distribution.

FIG. 4 is an explanatory view (A) showing an example of the removal of a thin film in the present invention and an SEM image (B) thereof.

Fig. 5 is an explanatory view of the variation of pore period depending on the anodizing conditions.

FIG. 6 is a schematic cross-sectional view of an example of a film according to the present invention.

FIG. 7 is a schematic cross-sectional view of another example of a membrane in the present invention.

FIG. 8 is a schematic diagram of a key portion of an example of the removing apparatus of the present invention.

FIG. 9 is a schematic diagram of a key portion of another embodiment of the removing device of the present invention.

FIG. 10 is a schematic diagram of a key portion of another embodiment of the removing device of the present invention.

FIG. 11 is a schematic diagram of a key portion of another embodiment of the removing device of the present invention.

FIG. 12 is a schematic diagram of a key portion of another embodiment of the removing device of the present invention.

FIG. 13 is a schematic diagram of a key portion of another embodiment of the removing device of the present invention.

FIG. 14 is a schematic diagram of a key portion of another embodiment of the removing device of the present invention.

In the figure: 6-target micro substance, 8-micro substance, 12-film, 14-pore, 16-photocatalytic layer, 18-film attached with photocatalytic layer, 20-flow channel, 21-inlet, 22-outlet, 25-push rod, 32-prefilter, 34-supporter, 40-irradiator, 42-irradiation light, 42 a-transmission light, 44-lens, 46-prism.

Detailed Description

The removing device and the removing method of the present invention will be explained below with reference to the drawings. The present invention is not limited to the following embodiments. Any modification within the range that can be conceived by a person skilled in the relevant art, such as addition, modification, and deletion, by other implementation methods is included in the scope of the present invention as long as the operation and effect of the present invention can be achieved.

The removing device of the present invention is provided with a flow channel for gas or liquid, and a porous membrane disposed in the flow channel, the membrane being made of metal oxide, having an average pore diameter of 5nm or more and 1000nm or less, and having a pore diameter distribution of pores having a relative standard deviation of less than 10%.

The removing method of the present invention is to arrange a porous membrane in a flow path of a gas or a liquid and allow the gas or the liquid to flow therethrough. The thin film is made of a metal oxide, has an average pore diameter of 5nm or more and 1000nm or less, and has a pore diameter distribution standard deviation of less than 5 nm.

Film(s)

The thin film of the present invention is disposed in the flow channel of the device, has a plurality of pores, and is made of a metal oxide. The average pore diameter of the fine pores is 5nm to 1000nm, and the relative standard deviation of the pore diameter distribution of the fine pores is less than 10%. The algorithm for the relative standard deviation is the standard deviation of pore size distribution/mean pore size of the fine pores. The fine pores of the thin film may also be referred to as through-holes.

Fig. 1A shows an SEM (scanning electron microscope) image of an example of the thin film of the present invention. Fig. 1A illustrates an example of an alumina thin film obtained by anodic oxidation (example 1). In the present embodiment, the film made of alumina is referred to as an alumina film.

The film of example 1 had an average pore size of 50nm and a standard deviation of 2.1 nm. The relative standard deviation (standard deviation/average) was 4.2%. In the thin film of the present embodiment, the fine pores formed are highly ordered, and therefore, the thin film is also referred to as a highly ordered thin film.

The average pore diameter of the thin film in the present embodiment is measured by SEM image and image analysis software, the pore size distribution is obtained by using image analysis software, and the standard deviation is measured by the pore size distribution thereof.

Fig. 1B shows an SEM image of the alumina thin film of comparative example 1. Since the alumina thin film of comparative example 1 had an average pore diameter of 50nm, a standard deviation of 5.2nm and a relative standard deviation of 10.4%, this example is not included in the present invention. A film with a low pore order formed like this is called a low order film.

Fig. 2 shows the pore size distribution of example 1 and comparative example 1. Fig. 2 shows the distribution of the pore diameters of the fine pores formed in the alumina thin films of example 1 and comparative example 1, which are normally distributed. As shown in the figure, the distribution of example 1 is steeper, and the distribution of comparative example 1 is gentler. In the example of fig. 2, the ratio of the pore diameter of the thin film of example 1 to about 50nm is high, whereas the ratio of the pore diameter of the thin film of comparative example 1 to about 50nm is small.

In general, the standard deviation is expressed as σ, with a cumulative probability of about 68.2% within a mean ± 1 σ. Likewise, the cumulative probability in the ± 2 σ, ± 3 σ.

1 σ: about 68.2%

+ -2 σ: about 95.4%

3 σ: about 99.7%

4 σ: about 99.99%

+ -5 σ: about 99.9999%

+ -6 σ: about 99.999999%.

FIG. 3 shows the standard deviation of a normal distribution versus cumulative probability for reference. Where the abscissa is labeled as standard deviation and may also be labeled as aperture.

The LRV (Log Reduction Value) index is used herein to illustrate the degree of removal of bacterial viruses and the extent to which they can be removed. The LRV can be determined by the ratio of the number of bacterial viruses before and after the treatment, the infectious titer, and the like. The LRV data is generally obtained by indicator bacteria or indicator viruses, and in some cases, by PCR detection or the like.

It will be explained that the removing device of the present invention has a high removing rate. The following discussion of LRV is based on the assumption of a perfect sphere that does not deform.

In the example of fig. 2, the cumulative probability is converted to LRV, and theoretically, LRV in the ± 5 σ range is about 6, LRV in the ± 6 σ range is about 8, and in the film of example 1(σ ═ 2.1nm), the LRV of about 6 corresponds to 10.5nm, and the LRV of about 8 corresponds to 12.6 nm. In contrast, in the film of comparative example 1(σ ═ 5.1nm), the portion with an LRV of about 6 corresponded to 25.5nm, and the portion with an LRV of about 8 corresponded to 30.6 nm. Therefore, in example 1, the pore size distribution is more increased in the portion where the LRV value is higher than in comparative example 1.

Further, since the pore diameter of the fine pores in example 1 is relatively regular, fine substances slightly larger than the average pore diameter are more easily removed (intercepted). As shown in FIG. 2, the film of example 1 can intercept fine particles having a size of about 55nm to 65nm, while the film of comparative example 1 is more difficult to intercept fine particles having a size of about 55nm to 65nm and let them pass through.

And further explained with reference to fig. 2. In the case of comparative example 1, the corresponding pore size distribution of the fine particles having a size of about 55nm to 65nm was in the range of 1 σ (5.1nm) to 3 σ (15.5nm), which corresponds to a cumulative probability of about 15.7% (see fig. 3), that is, about 15.7% of the fine pores of the thin film of comparative example 1 were allowed to pass through the fine particles. Therefore, comparative example 1 cannot have a high removal rate. In the example of FIG. 2, for example, the minute substance having a size of about 35nm to 45nm can be intercepted in example 1, but the minute substance passes through about 15.7% of the pores in comparative example 1.

It can be seen from this that, in the example of fig. 2, if the removal of only minute substances having a size of about 45nm to 55nm is aimed at, example 1 has a high removal rate, whereas comparative example 1 does not have a high removal rate. For example, in comparative example 1, minute substances having a size of about 55nm to 65nm directly pass through, while minute substances having a size of about 35nm to 45nm are intercepted.

Fig. 4 shows a specific case where the minute substance is removed. Fig. 4(a) is a schematic view showing the passage of the target fine substance 6 and the fine substance 8 in the air or the liquid on the film 12. The target fine substance 6 is larger than the pore diameter of the fine pore 14 and is intercepted on the surface of the thin film 12. In contrast, the fine substance 8 passes through the thin film 12 by being smaller than the pore diameter of the fine pore 14.

Fig. 4(B) is an SEM image of the thin film 12 intercepting the target minute substance 6. As shown, the target minute substance 6 is well intercepted. In the figure, the target fine substance 6 and the fine substance 8 are shown in the form of a ball as an example.

The present invention can make the removal rate of the target minute substance in the gas or liquid higher than that of the conventional art by adopting the thin film having the average pore diameter corresponding to the size of the target minute substance in consideration of the size of the target minute substance. Since some of the bacteria, viruses, and the like in gas or liquid may be present in a small amount enough to cause a malignant effect depending on the kind, the removal rate can be improved as described above, which is more effective than the conventional technique.

The "thin film having an average pore diameter corresponding to the size of the target fine substance" is not limited to the case where the size of the target fine substance completely matches the average pore diameter of the fine pores. Of course, the size of the target fine substance may be the same as or substantially the same as the average pore diameter, but the correspondence between the size of the target fine substance and the average pore diameter of the fine pores may be appropriately changed.

The average pore diameter of the film in the present invention is 5nm or more and 1000nm or less. If the conditions within this range are satisfied, a membrane having an evenly distributed pore diameter can be produced, and a membrane having a pore diameter suitable for filtering target fine substances such as viruses, bacteria, organic substances, garbage, and the like can be selected. The average pore diameter of the film is preferably 300nm or less, more preferably 200nm or less. Such a thin film has a higher virus removal rate when it is exposed to a virus as a target minute substance. Depending on the type of virus, a membrane having an average pore diameter of 100nm or less may be selected.

The membrane of the present invention preferably has a pore size distribution of pores having a relative standard deviation of 5% or less, more preferably 2% or less. The removal rate of the target micro-substances in the gas or the liquid is higher.

The thin film of the present invention preferably has a pore size distribution standard deviation of 5nm or less, more preferably 4nm or less. The removal rate of the target micro-substances in the gas or the liquid is higher.

The method for producing the thin film of the present invention will be explained below.

The fine-pored thin film can be prepared by a conventionally known method using a metal oxide. For example, one method is to form a porous oxide film on the surface of a metal such as aluminum by anodizing the metal in an electrolyte liquid and then changing the formation voltage.

When the anodic oxidation method is used for preparing the highly ordered film, a two-step anodic oxidation method is suitably adopted. In the two-step anodization method, first, a metal substrate such as aluminum in an electrolyte is electrified to complete a first anodization to form an oxide film, and the formed oxide film is removed. Then, the anodic oxidation treatment (second anodic oxidation) is performed again to form an oxide film again. After the first anodic oxidation, pits which are regularly arranged can be formed on the substrate, and after the second anodic oxidation, an oxide film with an ordered pore array can be formed. Removing a part of the oxide film from the substrate to obtain a thin film.

In addition to the above methods, a mold having an ordered array of bumps may be used to texture the metal surface so that it forms an array of depressions for anodization. When the metal is depressed by using the mold to perform anodic oxidation, the depressions are the starting points for the generation of fine pores, and thus a highly ordered thin film can be produced.

The highly ordered film can be prepared by reasonably adjusting the anodic oxidation conditions, so that the average pore diameter and the standard deviation of the pore diameter distribution meet the requirements of the research range. The order of the pore array of the alumina film is affected by the anodizing conditions, and when the anodizing is performed under suitable conditions, an ideal long-distance ordered structure in which pores are arranged in a long distance can be obtained. Under self-organized conditions, an ordered array of pores will advance as anodization proceeds. At the initial stage of monitoring of anodization, the generation of pores is random and the order of the pore array is low, but under the self-organization condition, when anodization proceeds, pores at the bottom of the thin film (also referred to as a barrier layer or the like) are rearranged with time, and a structure having a highly ordered array can be obtained.

The pore diameter and pore period of the thin film in the present invention, for example, an aluminum oxide film, are proportional to the conversion voltage during the anodic oxidation. Therefore, by changing the formation voltage while optimizing the formation conditions (the type of formation bath, etc.), it is possible to prepare thin films having different pore diameters and periods. Therefore, in order to obtain a thin film having an average pore diameter and a relative standard deviation satisfying the scope of the present invention, anodization may be performed by selecting an appropriate formation voltage and formation conditions.

Fig. 5 shows that the pore period of the alumina film is changed by changing the formation voltage during the anodic oxidation. (Electrochemistry, 83 (11)), 1006-. As shown, the pore period varies with the formation voltage. The pore size will also vary with formation voltage and formation conditions. In FIG. 5, 0.5M sulfuric acid electrolyte was used at a formation voltage of 25V (pore period 63nm), and 0.3M phosphoric acid electrolyte was used at a formation voltage of 195V (pore period 500 nm).

As for the preparation conditions of the anodic oxidation, for example, when the formation tank is oxalic acid 0.3M, the formation voltage is 40V, and the formation time is 160 hours, a highly ordered film having a pore period of 100nm and a pore diameter of 30nm to 70nm can be obtained. The film of example 1 (FIG. 1A) was prepared under conditions similar to those described above. The film of comparative example 1 was prepared under conditions different from those described above, and thus a highly ordered film could not be obtained.

In the present invention, "removing minute substances in a gas or liquid" may be referred to as "film intercepting minute substances". Further, "removing" includes "attaching to, adsorbing to, and preventing fine substances from being present on the film". When the film has a photocatalytic layer, the process of decomposing minute substances by the photocatalytic layer is also included in the range of "removal" as mentioned below.

The term "gas" as used herein includes, but is not limited to, air and other gas mixtures.

The term "liquid" as used herein is not limited to water, but may also include other solutions. In addition, the gas and the liquid may be mixed.

The "target minute substance in gas or liquid" referred to herein is not particularly limited and may be appropriately selected as appropriate, and includes viruses, bacteria, organic matter, garbage, and the like. The standard deviation of the pore size distribution of the membrane in the invention is very small, so the invention is suitable for removing the small-volume micro substances such as bacterial viruses. In addition, the removal device of the present invention is used for removing bacterial viruses, and therefore, may also be referred to as a bacterial virus removal device.

The "bacterial virus" referred to herein is not particularly limited and includes bacteriophage (about 20nm), feline calicivirus (about 30nm), influenza virus (about 100nm), coronavirus (about 100nm), gram-positive bacteria (about 1 μm), and the like. Retroviruses (about 80 to 130nm) such as HIV can also be targeted for removal. In addition, the numerical values in parentheses are merely for reference, and should be actually determined according to whether the virus has peaks or changes in shape.

The purpose of use of the removing apparatus and removing method of the present invention is not particularly limited. For example, the air or water can be purified for use, and harmful substances in the air or water can be removed, so that harm to human bodies is reduced. In addition, it can be used for medical purposes such as dialysis.

The present invention is also applicable to a measuring instrument and a measuring method. For example, in a device having a membrane, a gas or liquid is allowed to pass therethrough, and after a predetermined period of time, the membrane is removed from the device and measured by another measuring device. Thus, the minute substance intercepted on the film can be determined, and the kind and amount of the minute substance contained in the gas or liquid can be determined.

Gas or liquid is allowed to pass through the membrane, and after a period of time, the pores of the membrane may have bacterial virus attached. For this purpose, a method of providing a photocatalytic layer to decompose the attached bacterial virus can be used. In addition, bacteria, viruses, etc. attached to the membrane may be removed by, for example, purging (or washing). In this case, care should be taken to prevent spread of the purged bacterial virus.

The porosity of the film may be selected according to circumstances, and is preferably 20% or more and 40% or less. More than 20%, the obstruction to the gas or liquid flow can be reduced; below 40%, the pores may be tightly connected to each other to prevent the occurrence of a region having no independent pores.

The porosity of the film can be measured using SEM images and image analysis software.

The "pore period" referred to herein is not particularly limited. In general, it is preferably 10nm or more and 600nm or less, more preferably 100nm or less. In this case, the porosity is easily adjusted to the recommended range. The pore cycle is a distance from a pore adjacent to a pore when the pore is formed on a straight line.

The pores are preferably formed perpendicular to the surface of the film. This can reduce the probability that non-target fine substances, such as fine substances smaller than the average pore diameter, are difficult to pass through. Whether or not the fine pores are vertically formed can be confirmed by observing the SEM image of the cross section of the thin film. Further, the number of vertically formed fine holes may be measured by using image analysis software.

The proportion of the number of pores formed vertically is preferably 90% or more, more preferably 95% or more, and most preferably 99% or more. In this case, the removal efficiency of the minute substance can be improved. The film of example 1 (FIG. 1A) had a pore number of 99% or more.

The shape of the pore opening of the fine pore formed in the film may be selected according to circumstances, and may be a polygonal opening such as a triangle, a quadrangle, or the like, in addition to a circle. It may be not a regular polygon. Among them, a circular shape is preferable. Highly ordered films with circular orifice shapes are easier to prepare.

Although not particularly limited, the number ratio of the fine pores having a roundness of 0.9 in the orifice is preferably 90% or more, more preferably 95% or more, and most preferably 99% or more. Pore shapes can be obtained, for example, by SEM imaging, and analytically determined by imaging software.

The thickness of the film is not particularly limited, but is preferably 10 μm or more and 200 μm or less. It is easy to prepare a film within this range while ensuring strength.

The size of the film (length in the surface direction) is not particularly limited and may be selected as appropriate. The selection may be based on the configuration of the reference device, such as the size of the flow channel. The selection may be made according to the kind of the target fine substance. Such as a circle having a diameter of 10mm or more, or a circle having a diameter of about 30 cm. The shape is not limited to a circle, and may be selected according to the shape of the flow channel, etc.

The thin film used in the present invention is made of metal oxide. In the traditional virus removing device and method, a filter medium made of organic fiber is mostly adopted. In the invention, the film material is selected from metal oxide, so that ordered array of pores can be formed more easily. Among the metal oxides, alumina is particularly suitable for the preparation of highly ordered thin films in view of the convenience of the preparation process.

In addition to aluminum oxide, metal oxide such as titanium oxide, zirconium oxide, tungsten oxide, niobium oxide, cobalt oxide, tantalum oxide, hafnium oxide, iron oxide, vanadium oxide, or the like can be selected. In addition, when a metal oxide such as titanium oxide, tungsten oxide, iron oxide, or vanadium oxide is used, the thin film itself has a photocatalytic effect.

As for the thin film prepared by using the above metal oxide, reference is made to Electrochemistry, 83(11), 1006-.

The film used in the present invention preferably has a photocatalytic layer. The surface of the membrane with the photocatalytic layer is more easily decomposed and attached with bacteria and viruses, thereby reducing the blocking condition of the membrane. It is easier to remove the bacterial virus attached to the membrane, and it is also easier to use the membrane in a clean state.

The formation position of the photocatalytic layer is not particularly limited and may be selected according to circumstances. As shown in fig. 6 and 7.

Fig. 6 is a schematic cross-sectional view of a membrane 12 illustrating several cases where the membrane 12 has pores 14. The arrows in the figure indicate the direction of flow of the gas or liquid. In this example, photocatalytic layer 16 is formed on the surface of film 12, i.e., at the upstream surface position through which gas or liquid flows. Even if the photocatalytic layer 16 is formed on a part of the surface of the membrane 12 in this manner, the above-described effects can be achieved.

Fig. 7 is a schematic cross-sectional view of the film 12 as in fig. 6. The difference from the above example is that photocatalytic layer 16 in this example is formed so as to cover the entire surface of film 12. In this case, the photocatalytic layer 16 can decompose bacteria and viruses and the like adhering to the inside of the pores 14 of the thin film 12.

As described above, the formation position of the photocatalytic layer can be selected according to circumstances. As exemplified in fig. 6, the photocatalytic layer is preferably formed on one side surface of the membrane, and this surface is located upstream of the flow channels. Although the photocatalytic layer may be formed inside the pores, there is a problem in that the irradiated light may hardly reach the inside of the pores. Therefore, if the photocatalytic layer is formed on one side surface of the membrane, more photocatalysis can be provided to help decompose bacteria, viruses and the like. In addition, the formation of the photocatalytic layer can prevent the pore diameter of the pores from becoming small.

If the photocatalytic layer is formed on the thin film, the average pore diameter and standard deviation value of the thin film should be measured in a state where the photocatalytic layer is formed. Therefore, the pores of the thin film forming the photocatalytic layer should satisfy the aforementioned range, i.e., the average pore diameter is 5 to 1000nm and the relative standard deviation of the pore diameter distribution is less than 10%.

The photocatalytic layer can be selected according to circumstances, and for example, titanium oxide, tungsten oxide, cadmium sulfide, iron oxide, vanadium oxide, or the like can be used. Among them, titanium oxide is most preferable.

The thickness of the photocatalytic layer may be selected according to circumstances, but should be kept in proportion to the average pore diameter of the fine pores, and a thickness of 1% to 50% is preferable. For example, when the average pore diameter is 50nm, the thickness is preferably 0.5nm to 25 nm. In this range, the filtration is not impeded and the light can better promote the decomposition.

The method of forming the photocatalytic layer on the thin film may be selected according to circumstances. For example, an ALD (atomic layer deposition) method may be employed. Other methods are sol-gel (sol-gel) methods. Thin film coatings may also be formed using alkoxides. When the heat treatment method is employed, a uniform photocatalytic layer is more easily formed.

Example of the device Structure

An example of the apparatus structure of the removing apparatus of the present invention will be described. Hereinafter, "device" is also referred to as "removal device".

FIG. 8 is a schematic view of a key part of the apparatus installed in example 2. The device in this embodiment is provided with flow channels 20 through which gas or liquid flows, as well as membrane 12 and other corresponding necessary components. The arrows in the figure indicate the direction of flow of the gas or liquid.

According to the removing apparatus of this embodiment, the gas or liquid flowing through the flow channel 20 passes through the membrane 12, and the bacteria and viruses in the gas or liquid can be removed. Furthermore, the apparatus configuration of the removal device of the present embodiment is the same for both gas and liquid flows, which has the advantage that the apparatus can be easily assembled and switched.

The arrangement of the membrane 12, for example, the direction of the pores, is preferably the same as the direction of the flow of the gas or liquid in the flow channel 20. As illustrated in fig. 5, the direction of the fine pores 14 is the same as the direction of the gas or liquid flowing through the flow channel 20. This can reduce the obstruction of the gas or liquid flow when fine substances other than the target fine substance pass through the thin film.

Other embodiments are described below. FIG. 9 is a schematic view of the apparatus of example 3. The device in this embodiment is provided with a prefilter 32 having a larger average pore size than the membrane 12, located further upstream in the flow channel 20 than the membrane 12. The pre-filter 32 can remove large-sized garbage, organic matter, and the like, and prevent the membrane 12 from being clogged.

The pores of the pre-filter 32 may or may not be uniform.

The average pore size of the pre-filter 32 is preferably 2 times or more and 10 times or less the average pore size of the membrane 12. In this range, the gas or liquid in the flow channel 20 can be prevented from flowing slowly while removing dust and organic matter from the gas or liquid.

The material of the pre-filter 32 is not particularly limited and may be selected according to circumstances, such as metal, resin, and the like.

The apparatus of this embodiment is provided with a support 34 having an average pore size larger than that of the membrane 12, the support 34 being located downstream of the membrane 12 and in contact with the membrane 12. The support 34 may prevent breakage or deformation of the film 12 as much as possible.

The material of the support 34 is not particularly limited, and may be selected according to circumstances, such as metal, resin, and the like.

The holes of the support 34 may or may not be uniform.

The average pore diameter of the support 34 is preferably 2 times or more and 10 times or less the average pore diameter of the membrane 12. Within this range, the gas or liquid in the flow channel 20 can be prevented from flowing slowly, and the film 12 can be prevented from being damaged.

The apparatus for carrying out the method is preferably provided with a pressure regulator for regulating the pressure of the gas or liquid in the flow channel. The pressure regulator should apply pressure upstream of the membrane or reduce pressure downstream of the membrane. This increases the gas or liquid flow rate (the amount of gas or liquid passing through per unit time) of the membrane 12.

The pressure regulator may be selected according to circumstances, such as compressor, cylinder, etc. The method for applying pressure to the solution (liquid) flowing in the flow channel may be that inert gas (air, nitrogen, etc.) is first adjusted to a proper pressure in a compressor or a cylinder and then added into the solution; or the downstream of the membrane is decompressed, sucked and filtered, and negative pressure is added. When gas is in the flow channel, the gas at the upstream can be pressurized by a compressor and the like; it is also possible to add a negative pressure to the membrane downstream of it.

When a pressure regulator is used, it is preferable to use the support 34 at the same time, whereby breakage or deformation of the film 12 can be prevented as much as possible.

Other embodiments are described below. FIG. 10 is a schematic diagram of a key portion of the apparatus of example 4. As shown in the present embodiment, the structure of the flow path 20 may be changed as appropriate. The flow channel 20 is provided with an inlet 21 and an outlet 22, and allows pressurized gas or liquid to flow in through the inlet 21 and filtered gas or liquid to flow out through the outlet 22.

In this embodiment, the flow channel 20 may be made of a metal member. There is no particular limitation. The flow channel 20 can be prepared by using a member manufactured by Toyo Filter paper.

Other embodiments are described below. FIG. 11 is a schematic diagram of a key portion of the apparatus of example 5. As shown in the present embodiment, the structure of the flow path 20 may be changed as appropriate, and a flow path similar to a syringe may be used. In this embodiment, the gas or liquid in the flow channel 20 is pushed by the push rod 25 (plunger) towards the membrane 12, so that the filtered gas or liquid flows out of the outlet 22.

The push rod 25 may be used as an example of a pressure regulator.

The flow path 20 may be formed of a transparent member made of resin or the like. In this case, when the membrane 12 has the photocatalytic layer, the flow channel 20 can be irradiated with light from the outside.

Other embodiments are described below. FIG. 12 is a schematic diagram of a key portion of the apparatus according to example 6. The device of the present embodiment is provided with a film 18 to which a photocatalytic layer is attached, and an irradiator 40 that irradiates light to the photocatalytic layer.

The irradiator 40 irradiates the photocatalytic layer-attached film 18 with light 42 such as ultraviolet rays, thereby decomposing or removing bacteria and viruses on the photocatalytic layer-attached film 18 and keeping the film clean.

The configuration of illuminator 40 may be selected depending on the circumstances. As shown in this embodiment, it may be placed in flow channel 20 upstream of photocatalytic layer-attached membrane 18. Illuminator 40 may be disposed outside flow channel 20 or downstream of photocatalytic layer-attached film 18.

The structural member of the flow path may be made of a transparent material, and in this case, the irradiator may be disposed outside the flow path. When the irradiator is disposed outside the flow passage to pressurize the gas or liquid in the flow passage, the installation of the apparatus is simple.

The light irradiated by the irradiator 40 may be selected according to circumstances, such as ultraviolet light.

The light source of the illuminator 40 may be selected according to circumstances, such as an LED, UV light, and the like. The number of the light sources can be only 1 or more.

The irradiation time of the irradiator 40 may be selected depending on the situation, and may be long-term irradiation or irradiation at predetermined time intervals.

The light source can be placed outside the flow channel, and a light pipe (or called light pipe) or other components can be used to irradiate the film 18 with the photocatalytic layer in the flow channel.

In the present embodiment, if the pre-filter 32 is to be installed, the illuminator 40 may be disposed either upstream or downstream of the pre-filter 32. When illuminator 40 is disposed upstream of pre-filter 32, pre-filter 32 is preferably a transparent material. In this case, the loss of light emitted from the irradiator 40 can be reduced.

Other embodiments are described below. FIG. 13 is a schematic diagram of a key part of the apparatus of example 7. The apparatus of the present embodiment is provided with a film 18 having a photocatalytic layer attached thereto, and an irradiator 40 for emitting light thereto. In this embodiment, the light irradiator 40 is disposed outside the flow channel 20 on the side of the membrane 18 with the photocatalytic layer. In the present embodiment, the light 42 emitted from the light irradiator 40 is focused by the lens 44 and irradiated onto the film 18 with the photocatalytic layer.

Light irradiated from the side surface of the photocatalytic layer-attached film 18 propagates in the center direction of the photocatalytic layer-attached film 18. The thin film used in this embodiment has a higher refractive index than the surrounding medium, and thus does not leak light, and light can be efficiently transmitted, thereby realizing an efficient photocatalytic reaction.

In this embodiment, light may be irradiated from the side of the film 18 with a photocatalytic layer, and the constituent members of the flow channel 20 may be transparent or opaque. So long as the side of the film 18 having the photocatalytic layer attached thereto or the vicinity of the side is a transparent material.

Other embodiments are described below. FIG. 14 is a schematic diagram of a key portion of the apparatus according to example 8. In this embodiment, the lens in embodiment 7 is not used, but the coupler prism 46 is used as an optical coupling system. Illuminator 40 is also disposed outside flow channel 20, on the side of membrane 18 having a photocatalytic layer. This embodiment also enables efficient photocatalytic reactions.

In this embodiment, the light may be irradiated to the prism 46, for example, a transparent material may be selected at a part of the flow channel 20, so that the prism 46 can receive the light irradiation. In this embodiment, light impinging on the prism 46 is refracted or reflected within the prism 46 and is directed into the film from the bottom of the prism 46. The arrangement of the prism 46 may be changed depending on the situation.

Claims

1. A removal device, characterized by:

is provided with a flow passage through which gas or liquid flows,

a porous membrane disposed in the flow channel,

the thin film is made of a metal oxide,

the porous film has pores with an average pore diameter of 5nm to 1000nm, and a relative standard deviation of pore diameter distribution of 10% or less.

2. The removal apparatus of claim 1, wherein the bacteria and viruses in the gas or liquid can be removed.

3. The removal apparatus of claim 1 or claim 2, wherein the relative standard deviation of the pore size distribution is below 5%.

4. A removal apparatus as claimed in claim 3, wherein the relative standard deviation of the pore size distribution is below 2%.

5. A removing apparatus as claimed in any one of claims 1 to 4, characterised in that the porosity of the porous membrane is in the range 20% to 40%.

6. A removing device according to any one of claims 1 to 5, characterized in that the holes are formed perpendicularly to the surface direction of the porous film.

7. A removal device as claimed in any one of claims 1 to 6, wherein the aperture is circular in shape.

8. The removal device of any one of claims 1 to 7, wherein the metal oxide is alumina.

9. The removing device according to any one of claims 1 to 8, wherein the porous film has a thickness of 10 μm or more and 200 μm or less.

10. The removal device according to any one of claims 1 to 9, wherein the porous membrane has a photocatalytic layer.

11. The removing device according to claim 10, wherein the photocatalytic layer is formed on a surface of one side of the porous membrane, the surface of the photocatalytic layer being formed upstream in the flow channel.

12. The removing device as set forth in claim 10 or claim 11, wherein:

the photocatalytic layer is provided with an irradiator that irradiates light,

the illuminator is disposed in the flow channel, upstream of the porous membrane, or outside the flow channel, on a side of the porous membrane.

13. The removing device according to any one of claims 1 to 12, wherein a prefilter having a larger average pore size than the porous membrane is provided in the flow channel upstream of the porous membrane.

14. The removing device as set forth in any one of claims 1 to 13, wherein:

is provided with a support having an average pore size larger than that of the membrane,

the support is located at the downstream of the porous membrane and is in contact connection with the porous membrane.

15. The removing device as set forth in any one of claims 1 to 14, wherein:

provided with a pressure regulator for regulating the pressure of the gas or liquid in the flow passage,

the pressure regulator applies pressure upstream of the porous membrane or reduces pressure downstream of the porous membrane.

16. A removing method for disposing a porous membrane in a flow path through which a gas or a liquid flows, and allowing the gas or the liquid to pass, characterized in that:

the porous membrane is made of a metal oxide,