KR100703032B1 - Nano porous photocatalytic membrane, method of manufacturing the same, water treatment purification system and air purification system using the nano porous photocatalytic membrane - Google Patents

Abstract

The present invention provides a nanoporous photocatalyst membrane and a method for preparing an electrochemical electrolyzer containing an electrolytic solution, and forming a nanoporous metal oxide film having nanoporous pores by applying voltage to the anode and the cathode, which are spaced apart from each other. The present invention relates to a water treatment purification system and an air purification system using nanoporous photocatalyst membranes. According to the present invention, it is possible to manufacture a photocatalyst membrane having a nano-sized pore with high efficiency of photocatalyst by increasing the area of substantial contact with the fluid, and to reduce the processing cost by applying the nanoporous photocatalyst membrane to a water treatment or air purification system. It is possible to implement a water treatment or air purification system that is easy to carry and treat and has excellent treatment efficiency.

Photocatalytic, membrane, anodizing, porous, anatase, bulk micromachining, water treatment, air purification

Description

Nano porous photocatalytic membrane, method of manufacturing the same, water treatment purification system and air purification system using the nano porous photocatalytic membrane

1 is a view schematically showing a nano-porous metal oxide film production apparatus.

FIG. 2 is a view schematically showing a nanoporous titanium oxide film (TiO ₂ ) formed on a titanium (Ti) film.

3 to 5 are cross-sectional views illustrating a method of manufacturing a photocatalyst membrane by applying a silicon bulk micromachining process.

FIG. 6 is a view schematically showing a nanoporous aluminum oxide film (Al ₂ O ₃ ) formed on an aluminum (Al) film.

FIG. 7 is a diagram illustrating a method of manufacturing a photocatalyst separator including a nanoporous titanium oxide film and a nanoporous aluminum oxide film.

8 is a view schematically showing a water treatment purification system according to a preferred embodiment of the present invention.

9 is a view schematically showing an air purification system according to a preferred embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

10: electrolytic cell 20: electrolyte solution

30: anode 40: cathode

50: power supply means 60: silicon substrate

65: titanium oxide film 70: nano sized pores

75: etching mask 80: micro-sized holes

100: reactor 110: water treatment inlet

120: water treatment outlet 130: nano porous photocatalyst membrane filter

140: UV lamp 150: transparent cover

160: sludge outlet 175, 180: pump

185: valve 190: circulating water inlet pipe

200: air purification system 210: pre-filter

220: activated carbon fiber filter 230: nano porous photocatalyst membrane filter

240: differential pressure gauge

The present invention relates to a photocatalyst separation membrane and a method of manufacturing the same, a water treatment purification system and an atmospheric purification system using a photocatalyst, and more particularly, a photocatalyst separation membrane having a nanoporous structure and a manufacturing method thereof, and a water treatment purification system using a nanoporous photocatalyst separation membrane. And an atmospheric purification system.

Industrial wastewater and household wastewater are the main causes of water pollution, and air pollution due to industrial development is a major cause of destruction of natural environment and ecosystem.

Commonly used wastewater treatment methods include biological treatment and chemical treatment.

The activated sludge process is a representative example of biological treatment. The activated sludge process requires a long time to decompose organic compounds, requires a large space to prepare a treatment facility, and in the case of waste water containing an aromatic organic substance which is a hardly decomposable substance, The disadvantage is that it does not decompose well.

Chemical treatment methods include iron oxidation, Fenton oxidation, ozone oxidation, and the like. The iron oxidation method uses oxidation and flocculation using ferrous iron and ferric iron, which is less expensive and easy to treat wastewater, but has a disadvantage of poor treatment efficiency. Although the Fenton oxidation method appears to be relatively excellent in treatment efficiency, a large amount of sludge in the form of iron hydroxide is generated, and in the case of wastewater containing hardly decomposable organic matter, it is rarely treated. Ozone oxidation is widely used for drinking water treatment, but the gas generated after ozone treatment has to be adsorbed with activated carbon, treatment costs are high, there is concern about secondary pollution by ozone, and wastewater containing various organic substances is treated. There is a disadvantage in that it is not suitable.

As described above, various treatment methods have been proposed to more efficiently treat wastewater and air pollution, which are necessarily accompanied with industrial development, but have not yet reached a satisfactory level.

Patent application No. 2001-004275, a prior art document relating to wastewater treatment, discloses an advanced wastewater treatment apparatus and method for purifying wastewater by configuring an ozone treatment process and an activated carbon treatment process in a single reactor. In addition, Patent Application No. 2001-0025969 discloses an advanced wastewater treatment apparatus and method using a metal film combined with an intermittent ozone injection backwashing method.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a photocatalyst separation membrane having nano-sized pores having a high efficiency of photocatalyst due to an increase in the area in contact with the fluid.

Another technical problem to be achieved by the present invention is to provide a method for producing a photocatalyst separation membrane having a nano-sized pore having a high efficiency of the photocatalyst due to an increase in the area substantially in contact with the fluid.

Another technical problem to be achieved by the present invention is to provide a water treatment purification system using a nanoporous photocatalyst membrane having a low water treatment cost, an easy treatment method, and an excellent treatment efficiency.

Another technical problem to be achieved by the present invention is to provide an air purification system using a nanoporous photocatalyst membrane having a low air purification cost, an easy treatment method, and an excellent treatment efficiency.

The present invention, in the photocatalyst separation membrane having a front, rear, edge edge portion and the region between the front and rear, wherein the region between the front and rear includes a metal oxide film having a nano-sized pores while functioning as a photocatalyst, The nano-sized pores provide nanoporous photocatalyst membranes which are formed to penetrate from the front side to the rear side of the photocatalyst membrane.

The photocatalyst separator may further include a metal film formed under the metal oxide film and made of a component necessary for the metal oxide film to be oxidized, and the metal film may be formed to penetrate through the nano-sized pores.

The photocatalyst separator may include a silicon substrate on which a plurality of micro-sized holes are selectively formed rather than the nano-sized pores, a buffer layer formed on the silicon substrate, and formed on the buffer layer. The metal oxide film may further include a metal film made of a component necessary for oxidizing, wherein the metal oxide film is formed on the metal film, and the metal film and the buffer layer may be formed to penetrate through the nano-sized pores. .

In addition, the photocatalyst separator has a metal film formed under the metal oxide film and necessary components for oxidizing the metal oxide film, an aluminum film formed under the metal film, and nano-sized pores formed under the aluminum film. An aluminum oxide film may be further included, and the metal film and the aluminum film may be formed to penetrate through the nano-sized pores.

In addition, the present invention, the step of preparing an electrochemical electrolyzer containing the electrolyte, a positive voltage is applied and the anode is formed a nano-porous metal oxide film, and a negative voltage is applied to the negative electrode for supplying electrons to the metal cations are separated from each other Disposing the power supply means for supplying voltage to the positive electrode and the negative electrode, applying a voltage to the positive electrode and the negative electrode, and adjusting the voltage applied to the electrolyte solution using an anodizing process. Forming a nano-porous metal oxide film having nano-sized pores on the metal film provided at the anode, and contacting the metal film at the bottom so as to penetrate through the nano-sized pores and exposed through the nano-sized pores Selectively removing the metal oxide layer and selectively removing the remaining metal layer to form a photocatalyst separation membrane. It provides a nanoporous photocatalyst membrane manufacturing method comprising the step of forming.

The forming of the nano-porous metal oxide film may include electrolyzing water molecules (H ₂ O) in the electrolyte into hydrogen ions (H ⁺ ) and hydroxyl group ions (OH ⁻ ) by electrolysis. Hydrogen ions (H ⁺ ) move toward the cathode, combine with electrons, and are released as hydrogen gas (H ₂ ), and the hydroxyl group ions (OH ⁻ ) move toward the anode to form oxygen ions (O ^{2 −} ) and hydrogen. Separating the ions (H ⁺ ), reacting the separated oxygen ions (O ^{2 −} ) with a metal cation to form a metal oxide film, and separating the hydrogen ions (H ⁺ ) from the metal oxide film Reacting to partially break the bond between the metal and the oxygen to form a hydroxide, and forming oxide-sized pores by generating an oxide etching on the surface between the metal oxide film and the electrolyte.

The metal film is a metal film deposited on a front surface of a silicon substrate, and after forming the nanoporous metal oxide film, a micro-sized microparticle having a larger size than the nano-sized pores on the back surface of the silicon substrate using a silicon bulk micromachining process. and selectively forming a hole having a micro size.

The metal film is a metal film deposited on the entire surface of the aluminum substrate, while forming the nanoporous metal oxide film on the metal film to form an aluminum oxide film having nano-sized pores on the back of the aluminum substrate, while etching the metal film The method may further include selectively etching the aluminum substrate remaining under the aluminum oxide layer to penetrate through the pores.

A wet etching method, a dry etching method, a sand blast method, a blowing method, or an ion milling method is performed on the remaining metal film so that the front and rear surfaces of the remaining metal film penetrate through the pores. Can be selectively removed using law.

The metal film is a titanium (Ti) film, the metal oxide film is a titanium oxide film (TiO ₂ ) made of an anatase phase, and the pore size is preferably smaller than 100 nm.

The present invention also provides a water treatment purification system for purifying wastewater, sewage, or drinking water, comprising: a reaction tank for purifying and discharging introduced raw water, a water treatment inlet for introducing raw water into the reaction tank, and raw water introduced into the reaction tank A plurality of nanoporous photocatalyst separator filters containing a water treatment outlet discharged after treatment and purification, a metal oxide film having nano-sized pores for photocatalytic reaction, and performing physical and chemical fluid purification through the nano-sized pores; It provides a water treatment purification system using a nano-porous photocatalyst membrane comprising an ultraviolet lamp for irradiating the ultraviolet to the photocatalyst membrane filter in order to increase the activity of.

The photocatalyst membrane filter includes a photocatalyst membrane including the metal oxide layer having nano-sized pores and a metal membrane provided under the metal oxide layer and penetrating through the pores, wherein at least one photocatalyst membrane is arranged or mutually disposed. It can be a photocatalyst separator filter bonded and surrounded by a nonwoven fabric or metal mesh. The photocatalyst separator may further include a silicon substrate penetrating through the micro-sized hole rather than the nano-sized pores under the metal layer. The photocatalyst separation membrane may further include an aluminum oxide film disposed under the metal film and penetrated through the nano-sized pores, and an aluminum oxide film having nano-sized pores formed under the aluminum film.

The nanoporous metal oxide film is a titanium oxide film (TiO ₂ ) having a nano-sized pore and made of an anatase phase, and the pore diameter is preferably smaller than 100 nm.

In addition, the present invention is an air purifying system for collecting and removing dust or harmful gas in the air or adsorbing odors, the pre-filter for collecting large particles in the dust contained in the air, and the active carbon fiber Activated carbon fiber filter for adsorbing and deodorizing malodorous substance through small pores, and metal oxide film having nano sized pores for photocatalytic reaction, and performing physical and chemical air purification through the nano sized pores Provided is an air purification system using a nanoporous photocatalyst membrane comprising a nanoporous photocatalyst membrane filter.

The photocatalyst membrane filter includes a photocatalyst membrane including the metal oxide layer having nano-sized pores and a metal membrane provided under the metal oxide layer and penetrating through the pores, wherein at least one photocatalyst membrane is arranged or mutually disposed. It can be a photocatalyst separator filter bonded and surrounded by a nonwoven fabric or metal mesh. The photocatalyst separator may further include a silicon substrate penetrating through the micro-sized hole rather than the nano-sized pores under the metal layer. The photocatalyst separation membrane may further include an aluminum oxide film disposed under the metal film and penetrated through the nano-sized pores, and an aluminum oxide film having nano-sized pores formed under the aluminum film.

The nanoporous metal oxide film is a titanium oxide film (TiO ₂ ) having a nano-sized pore and made of an anatase phase, and the pore diameter is preferably smaller than 100 nm.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the following embodiments are provided to those skilled in the art to fully understand the present invention, and may be modified in various forms, and the scope of the present invention is limited to the embodiments described below. It doesn't happen. Like numbers refer to like elements in the figures. Nano size is a term commonly used in the art to those skilled in the art, and nano size generally means a size of 1 nm or more and less than 1000 nm (size of nano units of 1 nm or more and less than 1 μm). do.

A photocatalyst is a substance that absorbs light and shows a catalytic action, and helps to induce the initial reaction. The photocatalyst can oxidize and decompose hardly decomposable organic toxic substances such as benzene, phenol, TCE, etc., and also acts as antifouling, antibacterial, and deodorant.

When light energy above the energy gap between the valence band and the conduction band of the photocatalyst is received, electrons are excited in the conduction band at the valence band. Since the excited electrons have enough energy to cause the desired chemical reaction, the reactants can be used as an adsorbent to reduce the reactants, and the holes generated when the electrons are excited in the valence band can oxidize the reactants. Electrons and holes formed through such a process cause a photocatalytic reaction. This photocatalytic reaction utilizes the principle of converting light energy such as ultraviolet rays into chemical energy and causing a chemical reaction.

As a photocatalyst material, a titanium oxide film (TiO ₂ ) may be used. The titanium oxide film (TiO ₂ ) has an energy gap of 3.2 eV, is chemically and biologically stable, does not easily cause corrosion, and is very inexpensive. Titanium oxide (TiO ₂₎ is present in both the form of the anatase phase (anatase phase) and daily doubles, a titanium oxide film on the anatase (TiO ₂₎ can be processed in high temperature more than 1100Å is changed into rutile daily. The titanium oxide film (TiO ₂ ) may be manufactured to have an anatase phase in nanoporous form by using an anodizing process according to a preferred embodiment of the present invention.

Hereinafter, a process of forming a titanium oxide film (TiO ₂ ) made of an anatase phase in nanoporous form using an anodizing process will be described.

1 is a view schematically showing a nano-porous metal oxide film production apparatus.

Referring to FIG. 1, an apparatus for manufacturing a nanoporous metal oxide film includes an electrochemical bath 10, an anode 30 to which a positive voltage is applied and a nanoporous metal oxide film is formed, and a metal to which a negative voltage is applied. A cathode 40 for supplying electrons to the cation, an electrolyte solution 20 contained in the electrolytic cell 10, and a power supply means 50 for supplying voltage to the anode 30 and the cathode 40. do. The anode 30 and the cathode 40 are spaced apart from each other at a predetermined distance. The anode 30 is composed of the same components as the metal components of the nanoporous metal oxide film to be obtained. For example, when forming a titanium oxide film (TiO ₂ ), a titanium (Ti) film is used as the anode 30. The titanium film may be a titanium film deposited on a substrate such as silicon (Si). As the electrolyte solution 20, an acid solution such as hydrofluoric acid (HF), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), oxalic acid, or a mixture thereof may be used.

In order to form a nanoporous titanium oxide film (TiO ₂ ), a titanium film or a titanium (Ti) film deposited on a silicon substrate is prepared, and mounted on the anode 30. As the cathode 40, an acid resistant metal electrode such as platinum (Pt) or tantalum (Ta) is used. The positive electrode 30 is installed to be immersed in the electrolyte 20 by maintaining a constant interval with the negative electrode 40. In order to facilitate electrolysis or chemical reaction, an ultraviolet light source (not shown) may be positioned above the electrolytic cell 10 so that ultraviolet light may be irradiated onto the electrolyte solution 20. The anode 30 and cathode 40 are connected to a power supply 50 for applying a voltage or current. The voltage applied to the anode 30 is about 0V to 200V, and the voltage applied to the cathode 40 is about 0V to -200V. The voltage difference between the positive electrode 30 and the negative electrode 40 is appropriately adjusted in consideration of the size of the formed pores, the depth of the pores, the size of the cells, the thickness of the metal oxide film formed, and the like, and preferably at least 0.5V do. The electrolytic cell 10 may be provided with a constant temperature maintaining device (not shown) to prevent a sudden temperature rise due to an exothermic reaction during the anodizing process and to increase the uniformity of the electrolysis or chemical reaction throughout the metal film.

As the electrolyte solution 20 for forming the titanium oxide film, an acid solution such as hydrofluoric acid (HF), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), or a mixture thereof may be used. The electrolyte 20 facilitates the movement of charged electrons or ions to form a metal oxide film on the metal surface. In particular, metal ions (eg, Ti ⁴⁺ ) of the positive electrode material are dissolved in the electrolyte solution 20 at the electrolyte solution 20 and the oxide film interface, and the electrolyte solution 20 may form O ^{2 −} to form an oxide film at the oxide film and the metal interface. , OH ^- serves to supply radicals.

Looking at the anodizing process, the electrolytic solution 20 in the water molecule (H ₂ O), by the electrolysis of hydrogen ions as in reaction scheme 1 below (H ⁺⁾ and hydroxyl ion (OH ^-) are delivered in.

^{_{H 2 O → H + + OH}} -

Hydrogen ions (H ⁺ ) move toward the cathode 40 and are released as hydrogen gas (H ₂ ) by bonding electrons between the electrolyte solution 20 and the surface of the cathode 40.

The hydroxyl group ion (OH ⁻ ) moves toward the anode 30 and is separated into oxygen ions (O ^{2 −} ) and hydrogen ions (H ⁺ ) in a natural oxide film formed on the surface of the anode 30 (titanium film). At this time, the separated oxygen ions (O ^{2 −} ) penetrate the natural oxide film and react with titanium ions (Ti ⁴⁺ ) between the natural oxide film and the titanium film to form a titanium oxide film (TiO ₂ ) as shown in Equation 2 below.

^{Ti 4 + + O 2 - →} TiO 2

In addition, hydrogen ions (H ⁺ ) react with the titanium oxide film (TiO ₂ ) to partially break the bond between titanium (Ti) and oxygen to form a hydroxide, which is dissolved in the electrolyte solution 20. That is, oxide etching occurs on the surface between the titanium oxide film TiO ₂ and the electrolyte solution 20. The titanium oxide film TiO ₂ is formed at the interface between the natural oxide film and the titanium film, and the titanium oxide film TiO ₂ is etched at the interface between the titanium oxide film TiO ₂ and the electrolyte, as shown in FIG. 2. An anatase titanium oxide film (TiO ₂ ) 65 having the same nano size porous is formed. The surface of the titanium oxide (TiO ₂ ) 65 has a cell structure arranged as shown in FIG. 2, and nano-sized pores 70 are formed in the center of the cell. Although the exact theory has not been established for nano-sized pore-forming processes, local overcurrent occurs in the titanium oxide film (TiO ₂ ) and the exothermic reaction caused by such overcurrent accelerates the local etching of the oxide by the electrolyte. It is believed that nano-sized pores are formed.

The nanoporous titanium oxide film (TiO ₂ ) formed as described above may be applied as a water purification filter or an air purification filter. By forming the titanium oxide film (TiO ₂ ) into a structure having nano-sized pores, the area of the surface of the photocatalyst substantially in contact with the fluid or air can be maximized. Anodizing using a titanium (Ti) film is not only formed into a titanium oxide film having nano-sized pores, but also an oxide film can be formed in an anatase phase that can act as a photocatalyst, thereby applying it to water treatment or air purification. The castle is very big.

The thickness (d _ox = tp + tb) of the titanium oxide film TiO ₂ is expressed by Equation 1 below by the voltage U _a supplied from a power supply 50 and the electric field strength E _a of the oxide film. Is determined accordingly.

_{d ox = U a / E a} = K a · U a

Here, K _a is an anodizing constant determined by the type and quality of the oxide film.

In the case of forming a nanoporous titanium oxide film (TiO ₂ ), the pore size (d), the pore depth (tp), the cell size (D), and the oxide film thickness (tp + tb) are the concentration of the electrolyte solution and the intensity of the applied voltage. Can be adjusted by appropriately controlling the process time, the temperature of the electrolytic cell, and the like. For example, the temperature of the electrolytic cell 10 may be set in a range of about 0 to 50 ° C. to manufacture a nanoporous titanium oxide film (TiO ₂ ).

Using the above-described process conditions, the pore size is 100 nm or less, the pore size variation is 30% or less, and the thickness of the oxide film is 100 nm or more to form a nanoporous titanium oxide film (TiO ₂ ).

Hereinafter, the manufacturing process of the photocatalyst separation membrane formed after the above-described anodizing process will be described.

When the nanoporous titanium oxide film is formed on the titanium film using the above-described anodizing process, a titanium film not formed of an oxide film may remain under the titanium oxide film. Selectively remove the titanium oxide film exposed through the nano-sized pores while contacting the titanium film at the bottom so as to penetrate through the nano-sized pores, and using the etching solution having an etching selectivity with respect to the titanium oxide film and the titanium film. By selectively etching only the titanium film it can be produced a photocatalyst separator from the front to the back. As the etching solution, hydrofluoric acid (HF), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), hydrogen peroxide (H ₂ O ₂ ), or a mixture thereof can be used. The titanium oxide film exposed through the pores while being in contact with the titanium film at the bottom may be removed by using an anisotropic dry etching method using a reactive gas.

In addition, the remaining titanium film exposed through the pores is dry etching using a reactive gas, a sand blast method by injecting and removing fine particles, a blowing method using a high pressure wind, It can also be drilled using an ion milling method using ions.

A support layer may be needed for the titanium oxide film to support the flow of fluid, and the titanium film may be used as such support layer.

In addition, when the titanium oxide film is formed thick enough to be used as a photocatalyst separator, a nanoporous titanium oxide film is formed on the titanium film using the above-described anodizing process, and the titanium film other than the nanoporous titanium oxide film is cut or etched. It can also be used as a photocatalyst separation membrane by selectively removing.

In the case of using a titanium film deposited on a silicon (Si) substrate as a support layer, a photocatalyst separator may be manufactured by applying a silicon bulk micromachining process used for manufacturing MEMS (MEM). have.

3 to 5 are cross-sectional views illustrating a method of manufacturing a photocatalyst membrane by applying a silicon bulk micromachining process.

Referring to FIG. 3, a titanium film (not shown) is deposited on a silicon substrate 60, and a titanium oxide film 65 having nano-sized pores 70 is formed on the titanium film using the above-described anodizing process. Form.

Although not described above, a buffer layer (not shown) may be further formed on the silicon substrate before the titanium film is deposited. The buffer layer is formed to ensure uniformity of the titanium film and to alleviate the difference in physical properties between silicon and the titanium film. Materials such as tantalum (Ta) and platinum (Pt) may be used as the buffer layer, and may be thinly and uniformly formed at a thickness of about 50 kPa to about 200 kPa, and are removed together when removing the residual metal film exposed to the pores.

Referring to FIG. 4, an etching mask, for example, a photoresist pattern 75, is formed on the rear surface of the silicon substrate 60 (the surface opposite to the surface on which the titanium film is deposited).

Referring to FIG. 5, the plurality of holes 80 having a micro size are formed by wet etching the silicon substrate 60 using an etching solution using the photoresist pattern 75 as an etching mask. The hole 80 is a concept including all types of pores, trenches, and the like, which are dug from the back side to the front side of the silicon substrate 60. Potassium hydroxide (KOH) solution, tetramethylammonium hydroxide (TMAH), etc. can be used as said etching liquid.

Alternatively, dry etching may be performed by using reactive ion etching (RIE) to form a micro-sized hole 80. As an etching gas used for the reaction ion etching, SF ₆ gas or C ₄ F ₈ gas may be used.

After the micro-sized holes 80 are formed in the silicon substrate 60, the photoresist pattern 75 is removed.

The titanium oxide film exposed through the pores while being in contact with the titanium film at the bottom may be removed by using an anisotropic dry etching method using a reactive gas. The titanium film remaining on the silicon substrate 60 under the titanium oxide film 65 (including the buffer layer when the buffer layer is formed) may be wet, dry, sand blast, or blow (described above). Blowing, ion milling (ion milling), etc. can be used to drill through the pores (70).

On the other hand, in the case of using a titanium film deposited on a silicon substrate, using the above-mentioned anodizing process to form a nano-porous titanium oxide film, etching solution having an etching selectivity with respect to the titanium oxide film and the remaining titanium film, titanium oxide film and silicon By using an etching solution having an etching selectivity with respect to the substrate, only a titanium film and a silicon substrate may be selectively etched through the pores to manufacture a photocatalyst separation membrane which is drilled from front to back. This method is applicable to the case where the thickness of the silicon substrate is small and thin.

The photocatalyst separator prepared as described above includes a nanoporous titanium oxide film having a front surface, a rear surface, an edge portion, and a region between the front surface and the rear surface, and functioning at least as a photocatalyst in the region between the front surface and the rear surface.

The photocatalyst separation membrane prepared as described above may be arranged in a manner of at least one or bonded to each other to be surrounded by a nonwoven fabric or a metal mesh to be a water purification filter or an air purification filter.

Photocatalytic titanium oxide film (TiO ₂ ) having nano-sized pores is used as a purification filter for water treatment, and can be used for various purposes such as household water purifiers, wastewater purifiers, and small-scale wastewater treatment devices. In addition, it can also be used as an air purification filter, it can be used in a car or home air purifier or indoor air conditioning system of a large building.

The nano-porous aluminum oxide layer (Al ₂ O ₃ ) may also be formed using the above-described anodizing process. Hereinafter, the process of forming the nanoporous aluminum oxide film (Al ₂ O ₃ ) using the anodizing process will be described. Nanoporous aluminum oxide film (Al ₂ O ₃ ) can be formed using a metal oxide film manufacturing apparatus shown in FIG.

An aluminum (Al) film is prepared and mounted on the anode 30. As the cathode 40, an acid resistant metal electrode such as platinum is used. The positive electrode 30 is installed to be immersed in the electrolyte 20 by maintaining a constant interval with the negative electrode 40. The voltage applied to the anode 30 is about 0V to 200V, and the voltage applied to the cathode 40 is about 0V to -200V. The voltage difference between the positive electrode 30 and the negative electrode 40 is appropriately adjusted in consideration of the size of the formed pores, the depth of the pores, the size of the cell, the thickness of the metal oxide film formed, and the like, and preferably at least 0.5V or more. do.

As the electrolyte solution 20 for forming the aluminum oxide film, an acid solution such as phosphoric acid (H ₃ PO ₄ ), oxalic acid, or a mixture thereof may be used.

Looking at the anodizing process, the electrolytic solution 20 in the water molecule (H ₂ O), by the electrolysis of hydrogen ions as in reaction scheme 3 below (H ⁺⁾ and hydroxyl ion (OH ^-) are delivered in.

^{_{H 2 O → H + + OH}} -

Hydrogen ions (H ⁺ ) move toward the cathode 40 and are released as hydrogen gas (H ₂ ) by bonding electrons between the electrolyte solution 20 and the surface of the cathode 40.

The hydroxyl group ion (OH ⁻ ) moves toward the anode 30 and is separated into oxygen ions (O ^{2 −} ) and hydrogen ions (H ⁺ ) in a natural oxide film formed on the surface of the anode 30 (aluminum film). At this time, the separated oxygen ions (O ^{2 −} ) penetrate the natural oxide film and react with aluminum ions (Al ³⁺ ) between the natural oxide film and the aluminum film to form an aluminum oxide film as shown in Scheme 4 below.

^{2Al 3 + + 3O 2 - →} Al 2 O 3

In addition, hydrogen ions (H ⁺ ) react with the aluminum oxide film (Al ₂ O ₃ ) to partially break the bond between aluminum and oxygen to form a hydroxide, which is dissolved in the electrolyte solution 20. That is, oxide etching occurs at the surface between the aluminum oxide film and the electrolyte solution 20. In this way, an aluminum oxide film is formed at the interface between the natural oxide film and the aluminum film, and an aluminum oxide film is etched at the interface between the aluminum oxide film and the electrolyte solution to form a nano porous aluminum oxide film. As shown in FIG. 6, the surface of the aluminum oxide layer has a hexagonal cell structure, and pores are formed in the center of the cell.

When the nanoporous aluminum oxide film (Al ₂ O ₃ ) is formed, the pore size (d), the depth of the pore (tp), the cell size (D), and the thickness of the oxide film (tp + tb) are the concentration of the electrolyte solution and the applied voltage. This can be controlled by appropriately controlling the strength, process time, and temperature of the electrolyzer. For example, the temperature of the electrolytic cell 10 may be prepared in the nano-porous aluminum oxide film (Al ₂ O ₃ ) in the range of about 0 ~ 50Å.

Using the above-described process conditions, the size of the pores is 100 nm or less, the pore size variation is 30% or less, and the thickness of the oxide film is 100 nm or more, thereby forming a nanoporous aluminum oxide film (Al ₂ O ₃ ). .

Even when the nanoporous aluminum oxide film is formed on the aluminum film by applying the anodizing process, the above-described photocatalytic separator manufacturing process may be applied, and a detailed description thereof will be omitted.

As another preferred embodiment of the present invention, a method of manufacturing a photocatalyst separator comprising a nanoporous titanium oxide film and a nanoporous aluminum oxide film will be described.

Referring to FIG. 7, a titanium film is first deposited on an entire surface of an aluminum substrate (or an aluminum film may be deposited on a titanium substrate). It is also possible to form a buffer layer between the titanium film and the aluminum substrate. A titanium oxide film having nano-sized pores is formed on the titanium film by using the above-described anodizing process, and an aluminum oxide film having nano-sized pores is formed on the rear surface of the aluminum substrate.

In order to fabricate the photocatalyst, wet etching, dry etching, and sand are applied to the titanium film remaining under the titanium oxide film and the aluminum substrate remaining under the aluminum oxide film (including the buffer layer when the buffer layer is formed) as described above. It is etched through the pores by using a blast (sand blast), blowing (ion) method, ion milling (ion milling) method. In this way, a photocatalyst membrane having a front and a rear surface can be made through the pores.

The method of forming the nanoporous metal oxide film using the above anodizing is not only applied to the titanium oxide film (TiO ₂ ) and alumina (Al ₂ O ₃ ), but also tantalum (Ta), niobium (Nb), vanadium (V), and hafnium. The present invention is also applicable to a case where a nanoporous metal oxide film is formed using a valve metal such as (Hf), tungsten (W), or the like.

Applicability using nanoporous oxide can be greatly expanded according to the characteristics of the oxide, nanoporous metal oxide film obtained through the anodizing of various metals can be applied to many fields such as electrical and electronics, environmental field, medical field.

Hereinafter, embodiments using the above-described nanoporous metal oxide film as a photocatalyst as a purification filter for water treatment or an air purification filter will be described.

8 is a view schematically illustrating a water treatment purification system using a nanophotocatalyst membrane.

Referring to FIG. 8, the water treatment purification system includes a reaction tank 100 for purifying and discharging raw water such as introduced waste water, sewage, or drinking water, and raw water, such as waste water, sewage, or drinking water, installed at an upper portion of the reaction tank 100. The water treatment inlet 110, the water treatment outlet 120 is installed on one side of the reaction tank 100, the treated water discharge outlet 120 is purified and discharged, the nano-porous metal oxide film for the photocatalyst (eg, nano-porous titanium oxide film (TiO ₂ ) And a plurality of photocatalyst membrane filters 130 manufactured using a) and an ultraviolet lamp 140 for irradiating ultraviolet rays to the photocatalyst membrane filters in order to increase the activity of the photocatalyst. The photocatalyst separator filter 130 manufactured using the nanoporous titanium oxide film TiO ₂ may be provided between the ultraviolet lamps 140 to activate the photocatalyst more. In addition, the water treatment purification system is provided with a transparent cover 150 so that the upper part of the solar light transmission, and a sludge discharge port 160 for discharging excess sludge at the bottom.

The reactor 100 for the photocatalytic reaction is obtained by immersing the nanoporous titanium oxide film in the photocatalyst separation membrane filter and connecting the pumps 175 and 180 installed outside with pipes or tubes to obtain filtered water by the operation of an external pump. have. The inside of the nanoporous titanium oxide film becomes negative pressure (-) by the operation of the external pumps 175 and 180, and at this time, a feed is introduced into the nanoporous titanium oxide film from the outside by the pressure difference, and at the same time, the nanoporous A photocatalytic reaction occurs on the surface of the titanium oxide film to remove organic matter.

Floating lightweight fine ceramics (not shown) may be further provided in the reactor 100. The floating lightweight fine ceramics is made of a ceramic material floating in water.

The photocatalyst separation membrane is manufactured in the same manner as described above. The nanoporous photocatalyst membrane filter 130 contains a photocatalyst membrane including a nanoporous metal oxide film, such as a nanoporous titanium oxide film (TiO ₂ ) or a nanoporous aluminum oxide film (Al ₂ O ₃ ), manufactured in the anodizing process described above. The photocatalyst separation membrane may include the metal oxide layer (eg, TiO ₂ ) having nano-sized pores and a metal layer (eg, Ti) provided under the metal oxide layer and penetrated through the pores. The photocatalyst separation membrane may further include a silicon substrate penetrating through the micro-sized hole rather than the nano-sized pores under the metal layer. The photocatalyst separation membrane may further include an aluminum oxide film disposed under the metal film and penetrated through the nano-sized pores, and an aluminum oxide film having nano-sized pores formed under the aluminum film.

The photocatalyst membrane filter 130 may be manufactured by arranging at least one or more photocatalyst membranes prepared as described above or bonding them to each other in a nonwoven fabric or a metal net.

The nanoporous titanium oxide film (TiO ₂ ) functioning as a photocatalyst converts hydroxyl group ions (OH ⁻ ) obtained through photolysis of water into hydroxyl radicals for removing hardly decomposable organic substances. The bacteria contained in the water are sterilized by the ultraviolet lamp 140, and when natural light and / or ultraviolet rays are irradiated onto the nanoporous titanium oxide film (photocatalyst), a radical having strong oxidation power is generated, and the organic compound is formed by the radical. Oxidative decomposition.

The lower portion of the reaction tank 100 is preferably provided to be inclined (that is, provided with a sloped slope) so that the sludge gathers to the lower portion and facilitates the discharge through the sludge discharge pipe 160. Since the sludge has a greater specific gravity than water, it is necessary to properly discharge it through the sludge outlet 160 because it is deposited under the reactor 100.

The contaminated fluid is introduced into the reaction tank 100 through the pump 175 and the water treatment inlet 110, and the inflow fluid may be treated with a maintenance component by floating lightweight fine ceramics. The fluid treated with the maintenance component is sprayed onto the photocatalyst membrane filter 130, and the photocatalyst and the contaminated fluid are reacted by the sunlight and the ultraviolet lamp 140 passing through the transparent cover 150 to purify the contaminated fluid. do. The purified sludge is discharged through the sludge outlet 160 and the valve 185, and the purified fluid is discharged to the outside through the water treatment outlet 120 and the pump 180.

The fluid discharged through the water treatment inlet 110 is purified in the reaction tank 100, is introduced into the water treatment inlet 110 again through the circulating water inlet pipe 190, and again through the water treatment inlet 110. It may be repeated to purify by inflow. The above process is repeated until the introduced fluid reaches a sufficiently purified level, and the final treated water may be discharged to the water treatment outlet 120 to obtain a desired level of purified fluid.

On the other hand, by introducing hydrogen peroxide (H ₂ O ₂ ) into the reaction tank, it is possible to further promote the oxidative decomposition of the fluid by using an oxidation reaction.

In the water treatment purification system according to the preferred embodiment of the present invention, a unit process for water treatment such as sewage, waste water, and drinking water is integrated in one reactor 100, thereby reducing the site area required for treatment. The transparent cover 150 is designed to be installed to allow sunlight to penetrate the upper portion thereof, thereby increasing the efficiency of the photocatalyst, and also allowing the treatment of the holding component by floating lightweight fine ceramics. In addition, by using the nanoporous titanium oxide film (TiO ₂ ) deposited in the reaction tank 100 as a photocatalyst, it is possible to secure the desired treated water quality, as well as the ultraviolet sterilization function using an ultraviolet lamp, trace harmful organic substances, volatile organic compounds and organic properties Simultaneous removal of contaminants is possible.

9 is a view schematically illustrating an air purification system using a nanophotocatalyst separator.

Referring to FIG. 9, the air purification system 200 according to an exemplary embodiment of the present invention includes a pre filter 210 and an activated carbon fiber (ACF) filter 220. ), A nanoporous photocatalyst membrane filter 230, and a differential pressure gauge 240.

The prefilter 210 serves to preferentially collect large particles in the dust contained in the air. The prefilter 210 may be made of a fiber nonwoven layer of a polyester base.

The ACF filter 220 serves to deodorize and adsorb malodorous substances through small pores of activated carbon fibers. The ACF filter 220 may have a structure in which activated carbon fibers are surrounded by a nonwoven fabric. In addition, the ACF filter 220 is a filter in which activated carbon particles or activated carbon fibers and thermoplastic or thermosetting fibers are impregnated in a binder on a paste, and then dried and bonded to each other, or a polyurethane sponge in which activated carbon particles are mixed with a foamed urethane solution and foamed. It may be a filter.

The nanoporous photocatalyst membrane filter 230 contains a photocatalytic separator including a nanoporous metal oxide film, such as a nanoporous titanium oxide film (TiO ₂ ) or a nanoporous aluminum oxide film (Al ₂ O ₃ ), manufactured in the anodizing process described above. The photocatalyst separation membrane is manufactured in the same manner as described above. The photocatalyst separation membrane may include the metal oxide layer (eg, TiO ₂ ) having nano-sized pores and a metal layer (eg, Ti) provided under the metal oxide layer and penetrated through the pores. The photocatalyst separation membrane may further include a silicon substrate penetrating through the micro-sized hole rather than the nano-sized pores under the metal layer. The photocatalyst separation membrane may further include an aluminum oxide film disposed under the metal film and penetrated through the nano-sized pores, and an aluminum oxide film having nano-sized pores formed under the aluminum film.

The nanoporous photocatalyst membrane filter may be made by arranging at least one or more photocatalyst membranes manufactured as described above or bonded to each other to surround the nonwoven fabric or a metal network.

Differential pressure gauge 240 functions to control the pressure inside the air purification system.

The contaminated air is first purified by the pre-filter 210 to protect the membrane before being purified by the nanoporous photocatalyst membrane filter 230, and then using the ACF filter 220 having a pore size of about several micrometers. Secondary purification. When the physical purification is completed as described above, physical and chemical purification is performed through nano-sized pores using the nanoporous photocatalyst membrane filter 230 manufactured by the anodizing process. By using the photocatalytic reaction, fine bacteria can be effectively removed.

According to the present invention, the surface of contact with fluid or air is maximized by the nanoporous titanium oxide film to increase sterilization efficiency of viruses, pathogenic bacteria, parasites, and the like in water or air. In addition, toxic and hardly decomposable organic compounds such as dioxins, benzenes, phenols, TCEs, and THMs can be oxidized and decomposed by photocatalysts and ultraviolet lamps without incurring expensive chemical costs, thereby facilitating water quality management and maintenance. In addition, it is possible to effectively remove the fine dust in the air by using a photocatalyst membrane filter, it is possible to implement an air purification system excellent in antibacterial and deodorizing function.

As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to the said embodiment, A various deformation | transformation by a person of ordinary skill in the art within the scope of the technical idea of this invention is carried out. This is possible.

Claims (25)

In a photocatalyst separation membrane having a front surface, a rear surface, an edge portion, and a region between the front surface and the rear surface, the region between the front surface and the rear surface includes a metal oxide layer having nano size pores while serving as a photocatalyst, wherein the nano size pores Nanoporous photocatalyst membrane, characterized in that is formed so as to penetrate from the front to the rear of the photocatalyst membrane. The method of claim 1, wherein the photocatalyst separator further comprises a metal film formed under the metal oxide film and made of a component necessary for the metal oxide film to be oxidized, wherein the metal film is formed to penetrate through the nano-sized pores. Nanoporous photocatalyst membrane. The method of claim 1, wherein the photocatalyst membrane, A silicon substrate in which a plurality of micro-sized holes are selectively formed rather than the nano-sized pores; A buffer layer formed on the silicon substrate; And Further comprising a metal film formed on the buffer layer and made of a component necessary for the metal oxide film is oxidized, The metal oxide film is formed on the metal film, the metal film and the buffer layer is nanoporous photocatalyst membrane, characterized in that formed to penetrate through the nano-sized pores. The method of claim 1, wherein the photocatalyst membrane, A metal film formed under the metal oxide film and formed of a component necessary for oxidizing the metal oxide film; An aluminum film formed under the metal film; And Further comprising an aluminum oxide film having a nano-sized pores formed under the aluminum film, The metal membrane and the aluminum membrane is nanoporous photocatalyst membrane, characterized in that formed to penetrate through the nano-sized pores. The nanoporous photocatalyst membrane of any one of claims 1 to 4, wherein the metal oxide film is a titanium oxide film (TiO ₂ ) made of an anatase phase, and the pore size is smaller than 100 nm. Preparing an electrochemical electrolyzer containing the electrolyte; Disposing a positive electrode to which a positive voltage is applied and a nanoporous metal oxide film is formed, and a negative electrode for supplying electrons to a metal cation by applying a negative voltage; Disposing power supply means for supplying voltage to the anode and the cathode and applying a voltage to the anode and the cathode; Forming a nanoporous metal oxide film having nano-sized pores on the metal film provided at the anode while controlling the voltage applied to the electrolyte solution using an anodizing process; And Forming a photocatalyst separation membrane by selectively removing the metal oxide film exposed through the nano-sized pores and selectively removing the remaining metal film while contacting the metal film at the bottom to penetrate through the nano-sized pores. Nanoporous photocatalyst membrane production method comprising a. The method of claim 6, wherein the forming of the nanoporous metal oxide layer comprises: Electrolyzing the water molecules (H ₂ O) in the electrolyte solution with hydrogen ions (H ⁺ ) and hydroxyl group ions (OH ⁻ ) by electrolysis; Electrolyzed hydrogen ions (H ⁺ ) move toward the cathode, combine with electrons, and are released as hydrogen gas (H ₂ ), and the hydroxyl group ions (OH ⁻ ) move toward the anode, whereby oxygen ions (O ^{2 −} ) ) And hydrogen ions (H ⁺ ) to separate; Reacting the separated oxygen ions (O ²⁻ ) with a metal cation to form a metal oxide film; And The separated hydrogen ions (H ⁺ ) react with the metal oxide film to partially break the bond between metal and oxygen to form a hydroxide, and generate oxide etching on the surface between the metal oxide film and the electrolyte to form nanoporous pores. Nanoporous photocatalyst membrane manufacturing method of claim 1 comprising the step of forming. The method of claim 6, wherein the metal film is a metal film deposited on the entire surface of a silicon substrate, and after forming the nanoporous metal oxide film, The nanoporous photocatalyst membrane manufacturing method of claim 1, further comprising selectively forming a hole having a micro size larger than the nano size pores on a back surface of the silicon substrate using a silicon bulk micromachining process. The method of claim 6, wherein the metal film is a metal film deposited on the entire surface of the aluminum substrate, while forming the nanoporous metal oxide film on the metal film to form an aluminum oxide film having nano-sized pores on the back of the aluminum substrate; And selectively etching the aluminum substrate remaining under the aluminum oxide layer to penetrate through the pores while etching the metal layer. 7. The method of claim 6, wherein wet metal etching, dry etching, sand blast, blowing, or the like is applied to the remaining metal film so that the front and rear surfaces of the remaining metal film penetrate through the pores. Method for producing a nanoporous photocatalyst membrane of claim 1, characterized in that it is selectively removed using an ion milling method. The metal film of claim 6, wherein the metal film is a titanium (Ti) film, the metal oxide film is a titanium oxide film (TiO ₂ ) formed of an anatase phase, and the pore size is smaller than 100 nm. Nanoporous photocatalyst membrane manufacturing method of claim 1 characterized in that. The method of claim 6, wherein the electrolyte solution is characterized in that the acid solution consisting of hydrofluoric acid (HF), sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), oxalic acid solution or a mixture thereof. 1 nanoporous photocatalyst membrane production method. In a water treatment purification system for purifying wastewater, sewage or drinking water, A reactor for purifying and discharging the introduced raw water; A water treatment inlet for introducing raw water into the reactor; A water treatment outlet for treating and purifying raw water introduced into the reactor; A plurality of nanoporous photocatalyst membrane filters containing a metal oxide film having nano-sized pores for the photocatalytic reaction, and performing physical and chemical fluid purification through the nano-sized pores; And The water treatment purification system using the nanoporous photocatalyst membrane of claim 1 comprising an ultraviolet lamp for irradiating the photocatalyst membrane filter with ultraviolet rays to increase the activity of the photocatalyst. The method of claim 13, wherein the photocatalyst membrane filter, The metal oxide film having nano-sized pores; And A photocatalyst separation membrane including a metal membrane provided below the metal oxide layer and penetrating through the pores; The water treatment purification system using the nanoporous photocatalyst membrane of claim 1, wherein the photocatalyst membrane is a photocatalyst membrane filter in which at least one of the photocatalyst membranes is arranged or bonded to each other and surrounded by a nonwoven fabric or a metal network. 15. The water treatment method of claim 14, wherein the photocatalyst separator further comprises a silicon substrate penetrating through the micro-sized hole rather than the nano-sized pores under the metal membrane. Purification system. The method of claim 14, wherein the photocatalyst separation membrane, An aluminum film provided under the metal film and penetrating through nano-sized pores; And The water treatment purification system using the nanoporous photocatalyst membrane of claim 1 further comprising an aluminum oxide film having nano-sized pores formed under the aluminum membrane. The nanoporous metal oxide film according to any one of claims 13 to 16, wherein the nanoporous metal oxide film is a titanium oxide film (TiO ₂ ) having a nano-sized pore and made of an anatase phase, and the pore diameter is smaller than 100 nm. A water treatment purification system using the nanoporous photocatalyst membrane of claim 1. The method of claim 13, wherein the reactor, A transparent cover to allow sunlight to penetrate the upper portion; And The water treatment purification system using the nanoporous photocatalyst membrane of claim 1, further comprising a sludge outlet having an inclined slope for discharging sludge in the lower portion. In the air purification system for collecting and removing dust or harmful gas in the air, A pre-filter for first collecting large particles in dust contained in air; An activated carbon fiber filter for adsorbing and deodorizing malodorous substances through very small pores of activated carbon fibers; And Atmospheric atmosphere using the nanoporous photocatalyst membrane of claim 1, comprising a nanoporous photocatalyst membrane filter containing a metal oxide film having nano-sized pores for photocatalytic reaction and performing physical and chemical air purification through the nano-sized pores Purification system. The method of claim 19, wherein the photocatalyst membrane filter, The metal oxide film having nano-sized pores; And A photocatalyst separation membrane including a metal membrane provided below the metal oxide layer and penetrating through the pores; At least one photocatalyst membrane is an air purification system using the nanoporous photocatalyst membrane of claim 1, characterized in that at least one of the photocatalyst membrane filter arranged or bonded to each other surrounded by a non-woven fabric or a metal network. The atmosphere using the nanoporous photocatalyst membrane of claim 1, further comprising a silicon substrate penetrating through the micro-sized hole in the lower portion of the metal layer rather than the nanopore. Purification system. The method of claim 20, wherein the photocatalyst membrane, An aluminum film provided under the metal film and penetrating through nano-sized pores; And Air purification system using the nanoporous photocatalyst membrane of claim 1 further comprising an aluminum oxide film having a nano-sized pores formed under the aluminum film. 23. The method of any one of claims 19 to 22, wherein the nanoporous metal oxide film is a titanium oxide film (TiO ₂ ) having a nano-sized pore and made of an anatase phase, and the pore diameter is smaller than 100 nm. An air purification system using the nanoporous photocatalyst membrane of claim 1. The air purification system using the nanoporous photocatalyst membrane of claim 1, wherein the prefilter is a filter made of a polyester matrix fiber nonwoven layer. The method of claim 19, wherein the activated carbon fiber filter, It is a filter in which activated carbon fibers are surrounded by a nonwoven fabric, activated carbon particles or a filter in which activated carbon fibers and thermoplastic or thermosetting fibers are impregnated and dried in a binder on a paste and bonded to each other, or a filter in which activated carbon particles are mixed with a foamed urethane solution and foamed. An air purification system using the nanoporous photocatalyst membrane of claim 1.

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