TW201526987A - Method of producing titania sol with nano silver particle, photo-catalyst coating solution, photo-catalyst component and the use - Google Patents

Abstract

This invention declares the method to produce ag/titania sol. The suspended complex nanosized particles of anatase structure titania in aqueous solution were synthesized by a sol-gel method using titanium tetrachloride as the precursors and nanosized silver particle were synthesized by silver nitrate Titanium tetrachloride is dissolved in aqueous solution of hydrogen chloride at low temperature. Ammonia solution is then added to form titanium tetrahydroxide. Hydrogen peroxide and silver nitrate are then added. The mixture is then heated between 60-100 DEG C to form titania sol.

Description

Preparation method of nano silver composite titanium dioxide sol photocatalyst

The invention discloses a method for preparing a titanium dioxide sol photocatalyst, which can be used as a raw material for a coating carrier, and discloses its application in decontamination, self-cleaning and antibacterial treatment, in particular to a nano-silver composite titanium dioxide sol photocatalyst. System of law.

A photocatalyst is a substance that promotes a chemical reaction by irradiation of light. The materials currently available as photocatalysts include oxides such as titanium dioxide (TiO ₂ ) and sulfides such as CdS. Among them, titanium dioxide is most commonly used as a photocatalyst because of its strong redox ability, high chemical stability and non-toxic properties. substance. Photocatalyst is good at treating extremely low concentrations of harmful chemicals in the air and does not release harmful substances by itself. Therefore, it is an excellent catalyst for environmental purification. Photocatalysts can produce functions such as deodorization, sterilization, antibacterial, antifouling and removal of harmful substances.

The crystal structure of titanium dioxide has three types of a tetragonal high-temperature rutile type, a low-temperature anatase type, and an orthorhombic brookite type. Among them, only anatase structure has the effect of photocatalyst. The photolysis mechanism of the photocatalytic treatment process is to excite the photocatalyst by ultraviolet light or sunlight to generate electrons and holes in the catalyst, thereby oxidizing the substances adsorbed on the surface, thereby cracking the substances adsorbed on the surface into small molecules. Taking titanium dioxide as an example, the titanium dioxide reaction starts from a wavelength of 400 nm (because the energy difference of titanium dioxide is about 3.1 eV, and the wavelength of light at 400 nm provides about 3.1 eV), and the titanium dioxide absorbs light energy to generate electrons (e- And the hole (h+), which has a relatively strong oxidizing power, can directly oxidize the pollutant molecules adsorbed on the surface of the material to decompose it, or oxidize water molecules adsorbed on the surface of the substance to hydroxyl radicals. (‧OH). The contaminants of the original macromolecules cleave the macromolecules into small molecules through photocatalytic photoreaction to achieve the purpose of contaminant removal.

Photocatalysts are widely studied and applied in environmental protection, energy, sterilization, and self-cleaning. Since 1972, Fujishma and Honda published in Nature for the first time in the journal Nature that TiO ₂ will decompose water to produce H ₂ and O ₂ after illuminating. More and more people are investing in research on the photocatalytic properties of TiO ₂ and are committed to various possibilities. Modification method to improve the effect of TiO ₂ photocatalyst.

The photocatalytic mechanism of surface metal modified titanium dioxide is reported by John T. Yates et al. in Chemical Review 1995, Volume 95, pp. 735-758. K. Rajeshwar et al., Pure Applied Chemistry, Vol. 73, No. 12, pp. 1849-1860, 2001, found that silver addition can increase the efficiency of reduction of Cr(VI) to Cr(III) by titanium dioxide. P. Falaras et al., Applied Catalysis B: Environmental 42 (2003) pp. 187-201, utilizes a silver-added titanium dioxide film to photocatalytically decompose methyl orange. Pierre Pichat et al., Photochem. Photobiol. Sci., 2004, 3, pp. 142-144, also disclose that silver addition enhances the rate at which titanium dioxide removes 2-chlorophenol from water; however, the prior patent documents are both powdered, large-grained titanium dioxide. And all use ultraviolet light as a light source.

The photocatalytic reaction of the titanium dioxide catalyst by ultraviolet light irradiation can be used to decompose organic substances in wastewater or drinking water. The photochemical reaction is a heterogeneous photocatalytic reaction in which titanium dioxide with a semiconductor nature is used to excite electrons from a covalent band to a conductive band under appropriate wavelength radiation to generate holes and electrons, and holes and Electrons react with water and oxygen to form hydroxyl radicals and peroxidic free radicals, which can react with organic matter to form new substances.

The principle of photocatalytic reaction is explained below. The electrons in the outer layer of the semiconductor material can be divided into two electron energy bands, which are a covalent band and a conduction band. The energy difference between the two bands is called Can have a band gap. While electrons are located in different energy bands, their ability to move is different. If the electrons are in the covalent band, they cannot move. The electrons in the conduction band can move freely in the crystal lattice. Reaction mechanism for heterogeneous photocatalytic catalysts. To carry out the photocatalytic reaction, the catalyst must be activated first, that is, a light source with a larger energy than the band gap is applied, and the electronic transition of the covalent band is excited to the conduction band to generate electrons and holes, and the electrons of the conduction band can be moved to the touch. The surface of the medium interacts with an electron acceptor (such as O ₂ ) adsorbed on the surface of the catalyst, allowing the oxygen molecules to carry away the electrons of the conduction band to form a radical species; likewise, the holes generated by the covalent band can be It interacts with an electron supply adsorbed on the surface of the catalyst (such as OH groups on the surface, multi-electron organic matter), and then further oxidizes the organic matter.

Titanium dioxide can be made into powder, directly into the waste water, or applied to the surface of the substrate. The ultraviolet light can accelerate the decomposition of organic substances in water and air, but it will face the surface area of how to recover powder and catalyst. Fully accepting problems such as exposure to ultraviolet light. In order to improve these problems, titanium dioxide is coated into a transparent film, and it is desired to increase the exposed area of titanium dioxide to increase the photocatalytic effect. This will not only solve the above problems, but also increase the use of titanium dioxide photocatalyst.

At present, the antibacterial effect of titanium dioxide itself has no good antibacterial effect under the condition of no ultraviolet irradiation, so how to improve the antibacterial effect of the material is how to compound with other materials.

Further, in order to produce a titanium dioxide film, several major preparation methods have been developed in recent years. A substrate having a large surface area is usually formed by chemical vapor deposition, and the principle is to use a chemical reaction to form a solid species in the reaction region by a chemical reaction, and further deposit a deposition technique on the surface of the carrier. The adsorption force is strong, there must be high temperature equipment, and the process is complicated.

The Republic of China Patent Application No. 92112034 discloses a method for synthesizing a crystalline titanium dioxide photocatalyst which is diluted with titanium tetrachloride or titanium sulfate, adjusted to pH with ammonia water, added with an appropriate oxidizing agent and inorganic acid, and combined with operating conditions to generate Titanium dioxide photocatalyst sol. This application does not clearly disclose the use of hydrogen peroxide as the oxidant and the photocatalyst content is between 0.5 and 10%.

The Republic of China Patent Application No. 96142648 discloses a transparent water-based nano sol gel coating composition which does not reduce visible light and solar transmittance of a transparent substrate, and a coating method thereof, which is mainly composed of a zeolite sol, the zeolite sol In order to prepare with alkoxide, the process is complicated.

The Republic of China Patent Application No. 95129291 is a "method of preparing a nano film by a low temperature process" which discloses a method for preparing titanium oxide.

The Republic of China Patent Application No. 92128954 discloses a method for preparing titanium dioxide nano-powder, which is modified by an oxide or an inorganic acid such as perchloric acid, and added with a modifier and a surfactant, and the method needs to be modified. Agents and surfactants, the process is more complicated.

The invention uses a titanium tetrachloride as a raw material to study a method for preparing a transparent nano titanium dioxide photocatalyst stable suspension agent, wherein the titanium dioxide is anatase crystal and the particles are nanometer. The titanium tetrachloride aqueous solution is first added with ammonia water to become titanium hydroxide, and then hydrogen peroxide is added thereto, and then heated at 70-100 degrees Celsius for several hours to obtain a transparent nano titanium dioxide crystal photocatalyst suspension agent. The product was analyzed by an X-ray diffractometer and a transmission electron microscope. The silver-containing titanium dioxide obtained by the present invention was a long-shaped nanoparticle having a major axis of about 10 nm and a minor axis of about 4 nm. The titanium oxide particle solution is plated on the carrier by an immersion coating method to obtain a transparent and strong titanium oxide film. Irradiation with ultraviolet light or fluorescent lamps shows strong photocatalytic activity. Since the present invention firstly adds titanium tetrachloride in an ice bath (0-5 ^o C) to an aqueous solution of hydrochloric acid, and then adds an aqueous solution of ammonia to prepare titanium hydroxide, a long strip of titanium dioxide nanoparticles can be formed, which Fluorescent or ultraviolet light irradiation has high photocatalytic effect and antibacterial effect.

Generally, when titanium dioxide is prepared at low temperature, most of the non-crystalline particles are formed, and it must be calcined at about 300 ° C to form anatase crystals. This type of crystal has a photocatalytic effect, but some carriers, such as general glass, Leather, cloth, etc. cannot withstand such high temperatures, and the present invention discloses that anatase nanocrystalline crystal particles are formed at the time of preparation, and when it is coated on a carrier, it is not required to be calcined at a high temperature. Titanium dioxide film can be used as a photocatalyst. However, the generally coated titanium dioxide aqueous solution is made of titanium alkoxide as a raw material, which is expensive and complicated in the production process. The invention uses a cheaper titanium tetrachloride as a raw material to prepare an aqueous solution of titanium dioxide containing silver and anatase crystals at a low temperature.

The invention is mainly applicable to self-cleaning and decontamination, and utilizes its special reaction mechanism to decompose pollutants by the photocatalytic property of titanium dioxide, and the focus of the invention is to reveal a sol for producing nano-scale silver composite titanium dioxide (sol) ), it is illuminated by fluorescent lamps or ultraviolet light, and has high photocatalytic effect and antibacterial effect.

The invention uses the cheaper titanium tetrachloride as a raw material to prepare an aqueous solution of anatase crystal titanium dioxide and nano silver composite at a low temperature. The nano-silver composite titanium dioxide film was prepared by using nanocrystalline crystal particle suspension coating method to prepare a transparent and stable suspended nanocrystalline crystal particle film. At the time of preparation, anatase nano titanium dioxide crystal particles and nano silver particles are formed, and after being coated on the carrier, it is not required to be calcined at a high temperature. The suspension solution is stable, and the nanoparticles do not aggregate and precipitate in a short time. This solution is neutral and therefore does not corrode the carrier.

The invention adopts a nanocrystalline crystal particle suspension coating method to prepare a titanium dioxide film, and produces a transparent, stable suspension and photocatalytic activity of the titanium dioxide nanocrystal crystal particle solution. The invention adopts the cheaper titanium tetrachloride as a raw material and uses silver nitrate as a silver particle raw material to prepare an aqueous solution of nano-sized silver composite titanium dioxide particles as a raw material for coating, and has a photocatalytic effect after coating. This nano-sized titanium dioxide has an anatase crystal form, so it does not need to be calcined at a high temperature. The suspension solution is very stable, and the nanoparticles do not aggregate and precipitate after more than one year. This solution is neutral and does not corrode the carrier.

First, titanium tetrachloride is added to a hydrochloric acid aqueous solution at 0 to 5 ° C to prepare an aqueous solution, and then 30% aqueous ammonia is added to become a titanium hydroxide colloidal solution. The colloidal solution was centrifuged and washed several times until there was no chloride ion (the titration of silver nitrate until no white silver chloride precipitated). The titanium hydroxide colloidal solution is further added with hydrogen peroxide and silver nitrate, and then heated in a three-necked flask to a condenser tube at a temperature of 60 to 100 degrees Celsius for a period of time to obtain a nano titanium dioxide photocatalyst suspension. The transparent titanium dioxide solution can be coated on glass or any carrier such as ceramics and plastic sheets. It can be applied to ultraviolet light or fluorescent lamps as a light source, which will produce relatively high catalytic activity, and has the functions of decontamination, self-cleaning and antibacterial. It is super hydrophilic. Moreover, the inventors have found that a nano titanium dioxide photocatalyst manufactured according to the method of the present invention has an antiviral effect, and the virus comprises an influenza A virus, an enterovirus.

S110~S118‧‧‧Steps

The first figure is a flow chart of the steps of a method for preparing a titanium oxide sol photocatalyst according to an embodiment of the present invention.

The second picture is an electron micrograph of nano silver composite titanium dioxide.

Please refer to the first figure. The first figure is a flow chart of the steps of preparing a titanium oxide sol photocatalyst according to an embodiment of the present invention. A method for preparing a titanium dioxide sol photocatalyst, the steps comprising:

a. In step S110, titanium tetrachloride is provided, and an aqueous solution of hydrochloric acid is added at 0 to 5 ° C to form an A solution;

b. Step S112, adding an NH ₄ OH alkaline solution to form a titanium hydroxide colloid, the pH of which is in the range of 7 to 12;

c. Step S114, adding silver nitrate, AgNO ₃ /TiO ₂ weight ratio of 1/10 to 1 / 1000, preferably weight ratio of 10% to 0.01%;

d. Step S116, adding hydrogen peroxide to form a B solution, the weight ratio of TiO ₂ /H ₂ O ₂ is between 1/2 and 1/10, and the molar ratio of hydrogen peroxide to titanium is preferably 2 to 1 to 5 to 1. The weight ratio of TiO ₂ /H ₂ O is between 0.01% and 2%, preferably between 1/200 and 2/98;

e. In step S118, the B solution is heated in the range of 60 to 100 ° C until the colloid completely disappears, that is, a silver composite titanium oxide sol is formed, and dispersed in a nanometer scale, and stably suspended in water. The above steps are not particularly limited to the order in which they are performed.

The transparent titanium dioxide glass substrate prepared by the silver composite titanium dioxide particles prepared by the invention has strong photocatalytic activity after being irradiated by ultraviolet light, has the functions of decontamination, self-cleaning and antibacterial, and has super hydrophilicity. Moreover, the inventors have found that a nano titanium dioxide photocatalyst manufactured according to the method of the present invention has an antiviral effect, and the virus comprises an influenza A virus, an enterovirus.

(Example 1)

In an ice bath at 0 ° C, TiCl ₄ was slowly dropped into distilled water to make a concentration of 5 mol (5 M), and then the solution was slowly added with 30% ammonia water, and stirring was continued until the pH of the solution was 7 After several centrifugation and water washing until the concentration of chlorine is less than 5000 ppm, it is added to distilled water at this time, and hydrogen peroxide and silver nitrate are added, and the weight of TiO ₂ /H ₂ O ₂ /H ₂ O/AgNO ₃ is added. The ratio is 1/2/97/0.05 (weight ratio), the solution is heated in a three-necked conical flask and heated at 90 ° C for 2 hours to obtain a nano-sized titanium dioxide sol, as shown in the second figure. Show.

(Example 2)

Same as in Example 1, except that the weight ratio of silver nitrate/titanium dioxide added was 2/100.

(Comparative Example 1)

Titanium dioxide is commercially available from Evonik-Degussa, Inc., model number P-25 to water in a weight ratio of 1/100.

(Comparative Example 2)

Same as in Example 1, except that the weight ratio of silver nitrate/titanium dioxide added was 0.01/100.

(Embodiment 2)

A method of forming a substrate having a surface formed with transparent nano silver composite titanium dioxide:

First, cleaning the substrate

The surface of the unwashed substrate may have oily substances or other impurities, which may cause uneven coating and peeling during calcination; the substrate is cleaned so that the titanium dioxide nanoparticles can adhere more firmly to the substrate. The procedure for cleaning the substrate is as follows:

1. The substrate is placed in a neutral detergent and ultrasonically shaken for one hour.

2. Clean the residual detergent on the surface of the substrate with deionized water and wash it with ultrasonic wave for one hour.

3. The substrate was placed in a sodium hydroxide solution and ultrasonically shaken for one hour.

4. The sodium hydroxide solution remaining on the surface of the substrate was washed with deionized water and ultrasonically shaken for one hour.

5. Place the substrate in an oven and dry it for storage.

Second, the coating method

An immersion coating method or a spray coating method can be employed. The steps in which the immersion coating is performed are as follows:

1. Place the coating liquid on the lifting machine;

2. Fix the glass substrate to the lifter;

3. The substrate is immersed in the coating liquid at a rate of 5-10 cm/min;

4. Start to lift the film, the rate of rise is 5-10cm / min;

5. After the film is finished, it is exposed to ultraviolet light for 30 minutes;

6. The treated substrate is placed in an oven and dried at 60-160 ° C to complete the primary coating of the nano silver composite titanium dioxide;

7. When making a multilayer film, repeat the above steps.

(test decontamination and self-cleaning effect)

The invention utilizes the methylene blue blue-catalyzed reaction as a standard to test the decontamination and self-cleaning effect. The present invention utilizes the sol immersion plating of the embodiment 1-2 on the glass to carry out the methylene chloride blue liquid phase photocatalytic reaction, and the titanium dioxide coating The film substrate is immersed in a methylene methacrylate solution (containing 10,000 ppm of methylene blue), surrounded by ultraviolet light having a wavelength of 254 nm (two 10 W lamps) or a fluorescent tube (two 10 W lamps), every After 10 minutes of sampling, the absorption value at a wavelength of 662 nm was measured by an ultraviolet-visible spectrometer after centrifugation, and the disappearance rate of methylene blue was judged by the change of the absorbance. The disappearance rate of methylene blue after the test for 4 hours was as follows.

Methylene blue disappearance rate (after 4 hours of light irradiation)

(testing the efficacy of antiviral)

The test virus types were enterovirus and influenza A virus. Example 1. A titanium dioxide sol was added in an amount of 2.5% according to the method specified in ASTM E 1052-96, and its antiviral rate was tested to be 99.9%. Comparative Example 1. According to the method specified in ASTM E1052-96, no titanium dioxide sol was added, and its antiviral rate was tested to be 0%.

S110~S118‧‧‧Steps

Claims (10)

A method for preparing a nano silver composite titanium dioxide sol photocatalyst, the steps comprising:
Providing titanium tetrachloride, adding an aqueous solution of hydrochloric acid at 0 to 5 ° C to form an A solution;
Adding an aqueous ammonia solution to form a titanium hydroxide colloid, the pH of which is in the range of 7 to 12;
Adding hydrogen peroxide to form a B solution, wherein the ratio of solid weight of titanium dioxide to water is 0.01% to 2%, and the molar ratio of hydrogen peroxide to titanium is between 2:1 and 5:1;
Adding silver nitrate to the B solution, at which time the ratio of silver nitrate is from 0.01% to 10% by weight of the solids of the titanium dioxide;
The B solution is heated in the range of 60 to 100 ° C until the colloid is completely hydrolyzed to form a stable transparent titanium oxide sol. The method for preparing a nano silver composite titanium dioxide sol photocatalyst according to claim 1, wherein the transparent titanium dioxide sol-based nano-sized solid particles are suspended in water, and the pH thereof is 6.5-10. For example, the method for preparing a nano-silver composite titanium dioxide sol photocatalyst according to claim 1 wherein the pH of the titanium hydroxide colloid is between 8 and 10, the titanium dioxide is a diamond-shaped pull, the long axis is ten nm, and the short axis is Four nanometers, nano silver is granular less than 100 nm. For example, the method for preparing a nano-silver composite titanium dioxide sol photocatalyst according to claim 1 wherein the molar ratio of titanium dioxide/hydrogen peroxide is between 1/2 and 1/10. For example, the method for preparing a nano silver composite titanium oxide sol photocatalyst according to claim 1 wherein the temperature of the B solution to which silver nitrate is added is between 80 and 99 °C. An antibacterial nano photocatalyst coating liquid comprising a solution of a nano silver composite titanium dioxide sol photocatalyst prepared by the method for preparing a nano silver composite titanium dioxide sol photocatalyst according to claim 1 of the patent application. An antibacterial photocatalyst member is a titanium dioxide sol obtained by a method for preparing a nano silver composite titanium dioxide sol photocatalyst according to claim 1 of a patent surface. An anti-viral photocatalyst member is a titanium dioxide sol obtained by a method for preparing a nano-silver composite titanium dioxide sol photocatalyst on the surface of a substrate. A method for utilizing an antibacterial photocatalytic member according to claim 7 of the patent application is a method of decomposing an organic substance by ultraviolet light, fluorescent lamp or sunlight to make the substrate have self-cleaning and decontaminating effects, and the base The material has antibacterial effect. A method for utilizing an anti-viral photocatalytic member according to claim 8 of the patent application is a method for decomposing an organic substance by ultraviolet light, fluorescent lamp or sunlight to make the substrate have self-cleaning and decontaminating effects, and The substrate has antiviral properties.