KR20220095952A - Manufacturing method of visible light-responsive photocatalyst and photocatalyst thereof method - Google Patents

Abstract

The present invention relates to a method for manufacturing a visible light-responsive photocatalyst containing tungsten copper oxide colloid, and a visible light-responsive photocatalyst using the same. The visible light-responsive photocatalyst is composed of a mixture which includes 50 to 95 wt% of titanium oxide and 50 to 5 wt% of tungsten oxide (or copper tungsten oxide). The method for manufacturing a visible light-responsive photocatalyst comprises: a mixing step of mixing titanium hydroxide gel or crystallized titanium oxide as a titanium oxide material with tungsten oxide colloid as a tungsten oxide material in a set ratio, wherein the tungsten oxide colloid is made by passing, through a cation exchange resin, sodium tungstate obtained by inputting and heating an aqueous sodium hydroxide solution in tungsten oxide obtained by oxidizing cemented sludge; and a heat treatment step of heat-treating the mixture at 400 to 600℃. The present invention has an excellent photocatalytic effect for decomposing pollution materials.

Description

Manufacturing method of a visible light responsive photocatalyst containing copper tungsten oxide colloid and a visible light responsive photocatalyst using the same

The present invention relates to a photocatalyst and a method for manufacturing the same, and more particularly, to a manufacturing method for manufacturing a visible light responsive photocatalyst using CuWO ₃ colloidal suspension, and to a visible light responsive photocatalyst using the same.

Recently, in order to solve a serious environmental pollution problem worldwide, research on photocatalysts for decomposing or purifying pollutants using sunlight or indoor light is being actively conducted.

The photocatalyst absorbs light energy above the band gap, creates electrons and holes, diffuses to the surface of the photocatalyst particle, and participates in oxidation/reduction reactions, respectively. It refers to a substance that can oxidize or reduce a chemical.

Organic substances such as pesticides and odor substances in water or air using electrons and holes generated by such a photocatalytic reaction are decomposed, but most of them use titanium dioxide (TiO ₂ ). Since titanium dioxide has a band gap of 32 eV, it is active only under irradiation with ultraviolet rays shorter than 400 nm. Therefore, the current application is limited to outdoor or ultraviolet lamps.

Therefore, when developing a photocatalyst that responds to visible light, which accounts for 46% of sunlight, not only can a high-efficiency photocatalyst be made under sunlight, but it can also respond to fluorescent lamps indoors where sunlight cannot reach. be able to

That is, among the methods of removing harmful substances, a photocatalyst using clean and infinite solar energy is attracting attention, and in the case of titanium dioxide, which is known to be the most effective so far, it absorbs only ultraviolet rays with a short wavelength. There is an urgent need to develop a visible light responsive photocatalyst composition that can be absorbed.

Accordingly, studies on the photocatalytic effect on photocatalytic materials other than titanium oxide are being conducted, and one of them is the photocatalytic effect of tungsten oxide. Since tungsten oxide has a smaller energy band gap compared to titanium oxide, it is possible to absorb visible light. However, according to the results of studies to date, it is known that the photocatalytic activity is not great when tungsten oxide is used alone.

In other words, since the conduction band of tungsten oxide is lower than the oxidation-reduction level of oxygen, electrons do not contribute to the reduction reaction of oxygen and recombine with holes. Therefore, by forming an electron-absorbing material (eg, a co-catalyst) on the surface of the tungsten oxide particles, the recombination of electrons excited in the conduction band by light irradiation with holes generated in the valence band is suppressed, thereby enhancing the photocatalytic activity of the tungsten oxide particles. Copper or copper oxide is often used as such a co-catalyst.

It has been known for a long time that copper alone or copper ions have antibacterial properties, and books on bacteriostasis and sterilization by enzyme inhibition of target bacteria, membrane protein denaturation, and cell organelle protein denaturation have been studied until recently. And the copper-containing catalyst produced in anticipation of this effect is prepared by supporting copper oxide in the form of fine particles (Patent Document 1, Patent Document 2, Patent Document 3), and is used as various hygiene products.

However, copper-containing metal oxide has a high catalytic and antibacterial effect in the beginning because the composition of copper is easily changed by the surrounding environment such as light, heat, and moisture, but it deteriorates over time, so it is difficult to expect the effect.

In some cases, it is used in combination with a copper compound in order to enhance the antibacterial effect of the titanium oxide fine particles for a photocatalyst, which is disclosed in Patent Document 4. In addition, in order to obtain a sufficient photocatalytic effect in an indoor space, a visible light responsive photocatalyst must be used. As a visible light responsive photocatalyst, there is a tungsten oxide photocatalyst (Patent Document 5), and there is also a tungsten oxide photocatalyst in which a copper compound is supported on the surface ( Patent Document 6).

In addition, Patent Document 6 discloses a catalyst material in which titanium oxide is used as a core particle and tungsten oxide or copper-containing tungsten oxide is used as a co-catalyst and the entire surface is re-coated. In addition, Patent Document 7 discloses a visible light co-catalyst in which nano-scale titanium dioxide and tungsten oxide are sprayed and complexed by a sol-gel method. In addition, Pt is added to tungsten oxide, and patent document 8 discloses a Pt-added tungsten oxide photocatalyst coating agent. In addition, Patent Document 9 discloses a visible light responsive photocatalyst by preparing a tungsten oxide composite photocatalyst in titanium oxide in which a copper component is dissolved.

However, looking at the patent literature presented as a prior art, it is suggested that a catalyst that produces photocatalytic properties by using copper or Pt as a co-catalyst in titanium oxide fine particles is presented, but when titanium oxide is used as a catalyst, the photocatalytic effect is only in UV. To achieve a catalytic effect in visible light, centering on tungsten oxide, there are difficulties in manufacturing, such as manufacturing tungsten oxide from metal tungsten, or manufacturing a copper oxide tungsten compound using tungsten oxide and pulverized copper, and mechanical mixing over a long period of time There were difficulties such as having to

In addition, when tungsten oxide is used as a photocatalyst, there is a problem in performance as a photocatalyst because it adsorbs well in visible light but does not decompose well in a basic atmosphere, such as corrosion of tungsten oxide.

In order to improve this point, the present inventors conducted research on various methods for good synthesis when various metals or oxides are added as a co-catalyst to titanium oxide and which materials to mix as a co-catalyst. As a result, the present invention A visible light responsive photocatalyst material and a method for manufacturing a visible light responsive photocatalyst using the same were invented.

Patent Document 1: Japanese Patent Laid-Open No. 06-065012: Patent Document 2: Japanese Patent Laid-Open No. 11-349423 Patent Document 3: Japanese Patent Application Laid-Open No. 2007-31551 Patent Document 4: Japanese Patent Laid-Open No. Hei 08-067835 Patent Document 5: Japanese Patent Laid-Open No. 2009-148700 Patent Document 6: (Japanese Patent Laid-Open No. 2009-226299) Patent Document 7: JP 2019-181469 (2019.10.24.) Patent Document 8: KR 10-0578044 (2006.05.11.) Patent Document 9: KR 10-1527592 (2015.06.10.) Patent Document 10: KR 10-0945035 (2010.02.23.)

The present invention is to solve the problems of the prior art, and the main object of the present invention is to provide a visible light responsive photocatalyst capable of adsorbing and decomposing VOCs, viruses and bacteria in visible light.

In addition, the present invention expresses photocatalytic activity only with white light (400 to 800 nm), exhibits high antibacterial performance, and the copper coordination state is stable against heat or ultraviolet exposure, so it is not easily denatured and a durable photocatalytic thin film can be easily manufactured. An object of the present invention is to provide a catalyst in which platinum metal is dispersed as a co-catalyst in titanium oxide copper-containing tungsten oxide composite photocatalyst fine particles containing titanium oxide fine particles, a method for producing the same, and a photocatalyst formed using the dispersion.

As a means for achieving the object of the present invention, the visible light responsive photocatalyst according to the present invention consists of a mixture containing 50 to 95 wt% of titanium oxide and 50 to 5 wt% of tungsten oxide (or copper tungsten oxide) do it with

In addition, another embodiment of the present invention consists of a mixture containing 50 to 95% by weight of titanium oxide, 50 to 5% by weight of tungsten oxide (or copper tungsten oxide), and 0.001 to 0.1% by weight of platinum.

In the method for producing a visible light responsive photocatalyst according to the present invention, as a titanium oxide material, titanium hydroxide gel or crystallized titanium oxide, and as a tungsten oxide material, sodium hydroxide solution is added to tungsten oxide obtained by oxidizing cemented carbide, and sodium obtained by heating. A mixing step of mixing tungsten oxide colloid made by passing tungstate through a cation exchange resin in a certain ratio; It is characterized in that it comprises a heat treatment step of heat-treating the mixture at 400 ~ 600 ℃.

The above-described titanium hydroxide gel is made by dispersing a titanium metal salt solution in a solvent, thermally hydrolyzing it at a temperature of 60 to 100° C., washing with water or alcohol, and then separating and filtering.

The crystallized titanium oxide is made through the step of re-dispersing the titanium hydroxide gel made in the above step again in water and then putting it in a pressure vessel and heat-treating it at 100-300° C. for 100 hours.

The above-described tungsten oxide colloid is prepared by oxidizing cemented carbide sludge at a temperature of 600 to 800 ° C. After stirring to produce sodium tungstate, the prepared sodium tungstate is passed through a cation exchange resin.

In addition, tungsten copper oxide is made by reacting CuCl ₂ in anhydrous state with the tungsten oxide colloid prepared in the above step.

In addition, as a promoter, platinum can be added to either a titanium oxide sol or a tungsten oxide colloid.

In addition, in the method for producing a visible light responsive photocatalyst of the present invention, Ti(OH) ₄ doped with Pt and CuWO ₄ mixed in the above step is dried at 100° C. for 20 hours, and then heat-treated at 400° C. for 2 hours to obtain Pt, and a heat treatment step of preparing CuWO ₄ doped TiO ₂ .

In addition, the manufacturing method of the visible light responsive photocatalyst of the present invention includes the step of milling the TiO ₂ doped with Pt and CuWO ₄ prepared in the above step to prepare a nano-unit fine powder to produce a powder having a size of less than 50 nm. .

Since the visible light responsive photocatalyst prepared according to the present invention is activated in the visible light region such as general lighting including fluorescent lamps, LED and OLED lighting, the photocatalytic effect of decomposing contaminants is excellent.

The visible light responsive photocatalyst of the present invention has a superior photocatalytic effect in visible light than a photocatalyst using TiO ₂ and WO ₃ alone by preparing a nano photocatalyst by mixing tungsten oxide (or copper tungsten oxide) and titanium oxide in a certain ratio. have.

In addition, the method for producing a visible light responsive photocatalyst according to the present invention is made by using a titanium hydroxide gel obtained by hydrolyzing a titanium metal salt solution as a titanium oxide material and oxidizing cemented carbide instead of mixing titanium oxide powder and tungsten oxide powder. Tungsten oxide must be prepared from metallic tungsten by using a tungsten oxide colloid made by passing sodium tungstate obtained by heating aqueous sodium hydroxide solution in tungsten oxide through a cation exchange resin as a tungsten oxide material. There is an effect that can solve problems such as required.

1 is a photograph of a visible light responsive photocatalytic filter made according to the present invention.
2 is a photograph showing a test apparatus for measuring the removal rate of harmful gases of the visible light responsive photocatalytic filter made according to the present invention.

As the photocatalyst material, in addition to TiO ₂ , compounds such as WO ₃ , SrTiO ₃ , Fe ₂ O ₃ , SnO ₂ , ZnO may be used. By a photochemical reaction, the molecules in the ground state go through an excited state according to the region of each wavelength of light, and these are transformed into molecules of a new component with a low energy level.

The visible light responsive photocatalyst according to the present invention is composed of a mixture containing 50 to 95 wt% of titanium oxide and 50 to 5 wt% of tungsten oxide (or copper tungsten oxide).

In addition, the visible light responsive photocatalyst of the present invention comprises a mixture comprising 50 to 95 wt% of titanium oxide, 50 to 5 wt% of tungsten oxide (or copper tungsten oxide), and 0.001 to 0.1 wt% of platinum.

Specifically, the visible light responsive photocatalyst of the present invention uses TiO ₂ and WO ₃ as photocatalyst materials. TiO ₂ was confirmed to have an excellent photocatalytic effect in the ultraviolet region, but has a disadvantage in that the photocatalytic effect is insignificant in the visible region. That is, since ultraviolet light accounts for only about 4% of sunlight, photocatalytic efficiency is greatly reduced in an indoor environment where there is little ultraviolet light. On the other hand, WO ₃ has a photocatalytic effect in the visible region, but in the case of a photocatalyst using tungsten oxide alone, it is effective only at a specific wavelength, and it is known that the photocatalytic effect is generally small in visible light.

In consideration of this point, the present invention prepares a photocatalyst by heat-treating a mixture of TiO ₂ and WO ₃ in a predetermined ratio in order to increase the photocatalytic activity of TiO ₂ and WO ₃ . In this way, the photocatalyst prepared by heat-treating a mixture of TiO ₂ and WO ₃ has better photocatalytic effect in the visible light region than when TiO ₂ and WO ₃ are used alone.

In addition, in the manufacturing method according to the present invention, a mixture of TiO ₂ and WO ₃ is heat-treated in a predetermined ratio to prepare a photocatalyst, tungsten oxide is prepared from metal tungsten, or copper oxide tungsten using tungsten oxide and pulverized copper This is to solve problems such as difficulties in manufacturing in the prior art for preparing compounds and mechanical mixing over a long period of time is required.

To this end, the present invention prepares a mixture in which TiO ₂ and WO ₃ are mixed in a certain ratio, but for the titanium oxide, a titanium hydroxide gel obtained by hydrolyzing a titanium metal salt solution or a titanium oxide crystallized by heat treatment of a hydrated titanium gel is used.

And tungsten oxide uses a tungsten oxide colloid made by heating sodium tungstate obtained by adding an aqueous sodium hydroxide solution to tungsten oxide oxidized from cemented carbide sludge and passing it through a cation exchange resin.

Here, the colloidal suspension or colloid is a mixture in which a solvent and a solute are completely mixed to form a single phase, and an insoluble substance is dispersed and mixed with other substances with a size of 1 to 1000 nm, unlike a solution. Therefore, the tungsten oxide colloid is mixed with other materials in a state in which tungsten oxide fine particles are sprayed. When these tungsten oxide colloids are mixed with titanium hydroxide gel or titanium oxide, mechanical mixing for a long time is not required, and bonding with titanium oxide is easily achieved.

Specifically, the titanium oxide (TiO ₂ ) material is hydrolyzed according to the thermal hydrolysis process after dispersing the titanium metal salt solution in the solvent. At this time, the temperature of the thermal hydrolysis is 60 ~ 100 ℃. By performing the thermal hydrolysis in this way, an amorphous titanium hydroxide gel is obtained. Although the quantitative chemical formula of titanium hydroxide is Ti(OH) ₄ , it is not usually expressed as a quantitative chemical formula because Ti-OH bonds and Ti-O bonds are mixed in an amorphous state.

Then, after washing the titanium hydroxide gel with water or alcohol, it is separated and filtered to be used as a photocatalyst material, or the washed titanium hydroxide gel is re-dispersed in water and then placed in a pressure vessel for heat treatment, for example, heat treatment at 100~300℃ for 100 hours Thus, crystallized titanium oxide can be prepared and used as a photocatalyst material.

Next, since the material of tungsten oxide (WO ₃ ) is difficult to purchase in Korea and it is very difficult to produce tungsten oxide powder in a colloidal state, tungsten oxide colloid is manufactured from cemented carbide sludge and used.

That is, in order to produce colloidal tungsten oxide from cemented carbide sludge, a process of separating tungsten oxide and remaining impurities from cemented carbide sludge is required. Tungsten sludge is produced. Then, the prepared impurity-containing tungsten oxide is put into a solution of sodium hydroxide solution heated to 100° C. and stirred while heating to form sodium tungstate, thereby performing a process of separating it from impurities.

Then, the prepared sodium tungstat (sodium tungstate, sodium tungstate) is passed through a cation exchange resin to prepare a tungsten oxide colloid. A cation exchange resin is a synthetic resin that exchanges its own cations with cations in an aqueous solution. When sodium tungstate is passed through the cation exchange resin, the cations are exchanged to form tungsten oxide colloids.

Meanwhile, a second element such as copper may be added to the material of tungsten oxide (WO ₃ ). For example, copper is prepared by reacting anhydrous CuCl ₂ with colloidal tungsten oxide. That is, the addition of copper is prepared by reaction with a colloid of tungsten oxide.

The titanium dioxide gel prepared in this way and the tungsten oxide colloid (or the tungsten oxide colloid to which the second element is added) are mixed in an appropriate ratio and used as a photocatalyst material.

Preferably, the mixing ratio of titanium oxide and tungsten oxide is 50 to 95 wt% of titanium oxide and 5 to 50 wt% of tungsten oxide (or copper tungsten oxide).

In addition, platinum may be further added as a co-catalyst. Platinum (Pt) may be added to either titanium oxide sol or tungsten oxide colloid, but must be added before synthesizing titanium oxide and tungsten oxide colloid. At this time, platinum is added so as to be 0.001 to 0.1 wt% based on the total weight.

Platinum and tungsten oxide (or copper tungsten oxide) added titanium oxide prepared as described above are heat treated to prepare a visible light responsive photocatalyst. At this time, the heat treatment is carried out in the range of 400 to 600° C. so that the ratio of anatase (titanium dioxide) is 70% or more in the structure of titanium oxide to prepare a visible light responsive photocatalyst.

Hereinafter, examples of the present invention will be described in more detail, but the scope of the present invention is not limited to these examples.

<Example 1-1>

<Preparation of titanium oxide>

As the titanium oxide sol, Ti(OH) ₄ (Titanium Hudroxide, titanium hydroxide) obtained by treating TiCl ₄ was purchased from the market and used as a raw material.

<Manufacture of tungsten oxide>

Cemented carbide sludge produced as waste sludge was purchased from the market, put in a rotary kiln furnace at 700° C., and heated for 2 hours to oxidize tungsten carbide (tungsten carbide) to obtain tungsten oxide (WO ₃ ) powder.

This tungsten oxide powder contains impurities such as iron and nickel. Therefore, in order to obtain high-purity tungsten oxide by removing impurities from the tungsten oxide powder containing impurities, first, the impurity-containing tungsten oxide powder is placed in an aqueous solution of 20% sodium hydroxide and heated to 100°C while stirring to react only the tungsten oxide powder in an aqueous solution Sodium tungstate is prepared. At this time, the impurity becomes less than 0.1%.

Then, the content of sodium tungstate in aqueous solution was adjusted to 0.5 mol and passed through a cation exchange resin to prepare a high-purity tungsten oxide colloid.

<Added Copper>

Copper tungsten oxide (CuWO ₄ ) was prepared by reacting copper dichloride (CuCl 2 ) with high purity tungsten oxide colloid in a double jacket maintained at 5° C. based on 0.5 mol.

<mixed>

The Ti(OH) ₄ aqueous solution obtained above is synthesized by mixing CuWO ₄ in an amount of 5 wt% based on Ti. At this time, platinum as a co-catalyst is added in an amount of 0.1% by weight based on the total weight.

<dry>

The thus synthesized Pt, Ti(OH) ₄ doped with CuWO ₄ was dried at 100° C. for 20 hours, and then heat-treated at 400° C. for 2 hours to prepare TiO ₂ doped with Pt and CuWO ₄ .

<Crushing>

The thus prepared Pt, CuWO ₄ doped TiO ₂ was milled to prepare a nano-scale fine powder, and was prepared as a powder having a size of less than 50 nm.

<Photocatalyst Aqueous Solution>

After mixing the thus-prepared nano photocatalyst and distilled water in a ratio of 9:1, ethanol was mixed at a ratio of 50% by weight of the aqueous solution for dispersion, followed by stirring at 400 rpm at room temperature for 2 hours or more.

<Preparation of binder solution>

In order to attach the nano photocatalyst to the base substrate, an aqueous binder solution is prepared. At this time, the base binder was used as a material based on SMC-374-1 Si of Yeongil Hwaseong. A binder aqueous solution was prepared by mixing the binder and distilled water in a ratio of 1:9 and stirring at room temperature at 400 rpm or more for 2 hours or more.

<Manufacture of photocatalyst filter>

The thus prepared binder aqueous solution and the nano photocatalyst aqueous solution were mixed at a ratio of 9: 1 and stirred at 400 rpm for 2 hours or more to prepare a nano-catalyst binder aqueous solution, and after immersing a nickel alloy mesh of 15 cm × 15 cm, 4T, in a drying furnace at 250 ° C. or higher 1 A catalyst filter as shown in FIG. 1 was prepared by drying for more than an hour.

<Preparation of light source>

As shown in FIG. 2, the LED light source is manufactured by arranging 30 LH502Cs of Samsung Electronics. The LED light source emits white light of 400 to 800 nm. At this time, the illuminance measured on the photocatalytic filter was set to 10,000 lux or more.

<Photocatalytic Effect Experiment>

Using the manufactured photocatalyst filter and LED light source, the gas bag test method is used to test the removal rate of harmful gases with a detection tube. At this time, acetaldehyde was used as the harmful gas, and the initial concentration was set to 100 ppm.

<Example 1-2>

A nano photocatalyst was prepared except for Pt under the conditions of Example 1-1.

<Example 1-3>

A nano photocatalyst was prepared except for Cu under the conditions of Example 1-1.

<Example 2-1>

The heat treatment temperature of Pt and CuWO ₄ of Example 1-1 was performed at 450°C.

<Example 2-2>

A nano photocatalyst was prepared except for Pt under the conditions of Example 2-1.

<Example 2-3>

Under the conditions of Example 2-1, a nano photocatalyst was prepared except for Cu.

<Example 3-1>

The heat treatment temperature of Pt and CuWO ₄ of Example 1-1 was performed at 550°C.

<Example 3-2>

A nano photocatalyst was prepared except for Pt under the conditions of Example 3-1.

<Example 3-3>

A nano photocatalyst was prepared except for Cu under the conditions of Example 3-1.

<Example 4-1>

The heat treatment temperature of Pt and CuWO ₄ of Example 1-1 was performed at 600°C.

<Example 4-2>

A nano photocatalyst was prepared except for Pt under the conditions of Example 4-1.

<Example 4-3>

A nano photocatalyst was prepared except for Cu under the conditions of Example 4-1.

<Example 5-1>

The heat treatment temperature of Pt and CuWO ₄ of Example 1-1 was performed at 700°C.

<Example 5-2>

A nano photocatalyst was prepared except for Pt under the conditions of Example 5-1.

<Execution 5-3>

A nano photocatalyst was prepared except for Cu under the conditions of Example 5-1.

<Example 6-1>

The heat treatment temperature of Pt and CuWO ₄ of Example 1-1 was performed at 800°C.

<Example 6-2>

A nano photocatalyst was prepared except for Pt under the conditions of Example 6-1.

<Execution 6-3>

A nano photocatalyst was prepared except for Cu under the conditions of Example 6-1.

Heat treatment temperature 400℃ Example composition ratio initial concentration Concentration after light irradiation removal amount removal rate Example 1-1 Ti(OH) 95wt% +PtCuWO ₄ 5wt% 100 43 57 57% Example 1-2 Ti(OH) 95wt% + CuWO ₄ 5wt% 100 49 51 51% Examples 1-3 Ti(OH) 95wt% + PtWO ₄ 5wt% 100 52 48 48%

Heat treatment temperature 450℃ Example composition ratio initial concentration Concentration after light irradiation removal amount removal rate Example 2-1 Ti(OH) 95wt% +PtCuWO ₄ 5wt% 100 31 69 69% Example 2-2 Ti(OH) 95wt% + CuWO ₄ 5wt% 100 32 68 68% Example 2-3 Ti(OH) 95wt% + PtWO ₄ 5wt% 100 37 63 63%

Heat treatment temperature 550℃ Example composition ratio initial concentration Concentration after light irradiation removal amount removal rate Example 3-1 Ti(OH) 95wt% +PtCuWO ₄ 5wt% 100 33 67 67% Example 3-2 Ti(OH) 95wt% + CuWO ₄ 5wt% 100 35 65 65% Example 3-3 Ti(OH) 95wt% + PtWO ₄ 5wt% 100 40 60 60%

Heat treatment temperature 600℃ Example composition ratio initial concentration Concentration after light irradiation removal amount removal rate Example 4-1 Ti(OH) 95wt% +PtCuWO ₄ 5wt% 100 41 59 59% Example 4-2 Ti(OH) 95wt% + CuWO ₄ 5wt% 100 43 57 57% Example 4-3 Ti(OH) 95wt% + PtWO ₄ 5wt% 100 55 45 45%

Heat treatment temperature 700℃ Example composition ratio initial concentration Concentration after light irradiation removal amount removal rate Example 5-1 Ti(OH) 95wt% +PtCuWO ₄ 5wt% 100 75 25 25% Example 5-2 Ti(OH) 95wt% + CuWO ₄ 5wt% 100 79 21 21% Example 5-3 Ti(OH) 95wt% + PtWO ₄ 5wt% 100 81 19 19%

Heat treatment temperature 800℃ Example composition ratio initial concentration Concentration after light irradiation removal amount removal rate Example 6-1 Ti(OH) 95wt% +PtCuWO ₄ 5wt% 100 92 8 8% Example 6-2 Ti(OH) 95wt% + CuWO ₄ 5wt% 100 95 5 5% Example 6-3 Ti(OH) 95wt% + PtWO ₄ 5wt% 100 95 5 5%

As shown in the table above, when CuWO ₄ is mixed in Ti(OH) ₄ aqueous solution to 5% by weight based on Ti and heat treated at 400°C, the harmful gas removal rate is 57%, and when heat treated at 450°C, harmful gas removal rate is The gas removal rate is 69%, when the heat treatment at 550°C, the harmful gas removal rate is 67%, when the heat treatment at 600°C, the harmful gas removal rate is 59%, and when the heat treatment at 700°C, the harmful gas removal rate is 25% In the case of heat treatment at 800°C, the harmful gas removal rate was 8%.

Therefore, it was found that the heat treatment temperature of the Ti(OH) ₄ aqueous solution and the CuWO ₄ colloidal mixture was preferably 400 to 600°C. In addition, in the case of excluding platinum, the removal rate fell by about 1 to 6%, and in the case of excluding copper, it was found that the removal rate fell to 9 to 15%. That is, it has been shown to be advantageous to add copper rather than platinum.

<Example 7>

In Example 2-1, a nanophotocatalyst was prepared by mixing 10% by weight of PtCuWO ₄ by weight.

<Example 8>

In Example 2-1, a nano photocatalyst was prepared in an amount of 30% by weight of PtCuWO ₄ by weight.

<Example 9>

In Example 2-1, a nano photocatalyst was prepared in an amount of 50 wt% of PtCuWO ₄ by weight.

<Example 10>

In Example 2-1, a nano photocatalyst was prepared in an amount of PtCuWO ₄ in an amount of 70 wt%.

Heat treatment temperature 450℃ Example composition ratio initial concentration Concentration after light irradiation removal amount removal rate Example 7 Ti(OH) 90wt% +PtCuWO ₄ 10wt% 100 33 67 67% Example 8 Ti(OH) 70wt% +PtCuWO ₄ 30wt% 100 38 62 62% Example 9 Ti(OH) 50wt% +PtCuWO ₄ 50wt% 100 46 54 54% Example 10 Ti(OH) 30wt% +PtCuWO ₄ 70wt% 100 43 47 47%

As shown in the table above, when CuWO ₄ is mixed in Ti(OH) ₄ aqueous solution to 5% by weight based on Ti, the harmful gas removal rate is 69%, and when synthesized to be 10% by weight, the harmful gas removal rate is 67%, When synthesized to be 30% by weight, the removal rate of harmful gas was 62%, when synthesized to be 50% by weight, the removal rate of harmful gas was 54%, and when mixed to 70% by weight, the removal rate of harmful gas was 52%. That is, WO ₄ had the highest removal rate of harmful gases when the mixing ratio was 5 to 50% by weight, but the removal rate of harmful gases was not significantly reduced even when the mixing ratio of WO ₄ was increased to 70% by weight.

<Comparative Example 1>

The removal rate of harmful gas was tested in the same manner as in Example 1 for the nano photochemical solvent made of TiO ₂ alone.

<Comparative Example 2>

The removal rate of harmful gas was tested in the same manner as in Example 1 for a nano-photovoltaic medium composed of CuWO ₄ alone.

Heat treatment temperature 400℃ comparative amount composition ratio initial concentration Concentration after light irradiation removal amount removal rate Comparative Example 1 TiO ₂ 100 90 10 10% Comparative Example 2 CuWO ₄ 100 75 25 25%

As shown in the table above, in the case of the nano photo gunner made of TiO ₂ alone, the harmful gas removal rate was 10%, and in the case of the nano photo gunner made of CuWO ₄ alone, the harmful gas removal rate was 25%. On the other hand, since the nano photocatalyst prepared by mixing tungsten oxide (or copper tungsten oxide) and titanium oxide according to Example 1 has a harmful gas removal rate of 57%, the nano photocatalyst according to the present invention has excellent photocatalytic effect in the visible region. appear.

As described above, in the present invention, by preparing a nano photocatalyst by mixing tungsten oxide (or copper tungsten oxide) and titanium oxide in a certain ratio, a photocatalytic effect superior to that of a photocatalyst using TiO ₂ and WO ₃ alone is shown in visible light.

In addition, the present invention uses a titanium hydroxide gel hydrolyzed by a titanium metal salt solution as a titanium oxide material instead of mixing titanium oxide powder and tungsten oxide powder, and puts sodium hydroxide aqueous solution into tungsten oxide made by oxidizing cemented carbide sludge and heating it. By using the tungsten oxide colloid made by passing the obtained sodium tungstate through a cation exchange resin as a tungsten oxide material, tungsten oxide must be produced from metallic tungsten to solve problems such as manufacturing difficulties and long-term mechanical mixing. have.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art can variously modify and change the present invention within the scope without departing from the spirit and scope of the present invention described in the claims below. You will understand that it can be done.

Claims (10)

A visible light responsive photocatalyst comprising 50 to 95 wt% of titanium oxide and 50 to 5 wt% of tungsten oxide (or copper tungsten oxide).
A visible light responsive photocatalyst comprising 50 to 95 wt% of titanium oxide, 50 to 5 wt% of tungsten oxide (or copper tungsten oxide), and 0.001 to 0.1 wt% of platinum.
As a titanium oxide material, titanium hydroxide gel or crystallized titanium oxide, and, as a tungsten oxide material, a tungsten oxide colloid made by passing sodium tungstate obtained by heating an aqueous solution of sodium hydroxide into tungsten oxide oxidized from cemented carbide sludge through a cation exchange resin. A mixing step of mixing in a certain ratio;
A method for producing a visible light responsive photocatalyst, comprising a heat treatment step of heat-treating the mixture at 400 to 600°C.
4. The method of claim 3,
The above-described titanium hydroxide gel is a visible light responsive photocatalyst, characterized in that it is made by dispersing a titanium metal salt solution in a solvent, thermally hydrolyzing it at a temperature of 60 to 100° C., washing with water or alcohol, and then separating and filtering. manufacturing method.
4. The method of claim 3,
The crystallized titanium oxide is produced by re-dispersing the titanium hydroxide gel made in the above step in water, putting it in a pressure vessel, and heat-treating it at 100 to 300° C. for 100 hours. Preparation of a visible light responsive photocatalyst Way.
4. The method of claim 3,
The above-described tungsten oxide colloid is prepared by oxidizing cemented carbide sludge at a temperature of 600 to 800 ° C. A method for producing a visible light responsive photocatalyst, characterized in that the sodium tungstate is produced by stirring, and then the prepared sodium tungstate is passed through a cation exchange resin.
4. The method of claim 3,
As the titanium oxide material, tungsten copper oxide is used, but the copper oxide is produced by reacting CuCl ₂ in anhydrous state with the tungsten oxide colloid prepared in the above step.
8. The method of claim 7
A method for producing a visible light responsive photocatalyst, wherein platinum is further added as a co-catalyst, and the platinum is added to either a titanium oxide sol or a tungsten oxide colloid.
9. The method of claim 8,
After drying the Ti(OH) ₄ doped with Pt and CuWO ₄ mixed in the above step at 100° C. for 20 hours, heat treatment again at 400 to 600° C. for 2 hours to prepare Pt, CuWO ₄ doped TiO ₂ A heat treatment step A method for producing a visible light responsive photocatalyst, comprising:
10. The method of claim 9,
A method for producing a visible light responsive photocatalyst, comprising: milling the TiO ₂ doped with Pt and CuWO ₄ prepared in the above step to prepare a nano-unit fine powder to a powder of less than 50 nm.

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