KR100631337B1 - Preparation of Visible Light Responding Photocatalytic Coating Solution - Google Patents

Abstract

The present invention comprises the steps of mixing 0.1 to 6% by weight of ammonia water, 1 to 10% by weight titanium tetrachloride and 84 to 98.9% by weight of the solvent at 0 to 20 ℃ per weight of the total mixture; Dispersing the mixture with an ultrasonic vibrator for 5 to 30 minutes; Aging the dispersed mixture at 70 to 100 ° C. for 2 hours; After cooling the mixture at the end of the aging step at room temperature and dialyzed until the pH 2 to 5 using a membrane for preparing a photocatalyst coating comprising the step of preparing titanium dioxide doped with colloidal nitrogen and chlorine ions Provided are methods for preparing the sol.

According to the present invention, titanium dioxide and chlorine ions are doped into titanium dioxide, thereby exhibiting photocatalytic activity in the visible light region.

Visible light, titanium dioxide, nitrogen ion, chlorine ion, doping, photocatalyst

Description

Manufacturing method of sol for visible light responsive photocatalyst coating {Preparation of Visible Light Responding Photocatalytic Coating Solution}             

1 is a graph comparing ultraviolet / visible absorbances of titanium dioxide and titanium dioxide (P25) doped with nitrogen and chlorine ions according to the present invention;

2 is an electron microscope (TEM) photograph of titanium dioxide doped with nitrogen and chlorine ions according to the present invention;

3 is a graph showing the resolution of titanium dioxide doped with nitrogen and chlorine ions according to the present invention and conventional titanium dioxide.

The present invention relates to a method for preparing a photocatalyst coating sol, and more particularly, to a method for preparing a photocatalyst coating sol comprising titanium dioxide doped with nitrogen and chlorine ions by mixing and reacting ammonia water, titanium tetrachloride and a solvent. It is about.

After the Industrial Revolution, environmental problems are rapidly intensifying due to the acceleration of industrialization, and as a result, interest in air pollution is increasing, and most of the occupants living in buildings recognize the importance of improving the indoor environment and live in a comfortable indoor environment. I'm trying to. In particular, humans occupy more than 90% of their time indoors, and if indoor air is contaminated, it is not easy to clean, which acts as a threat to the health of inmates.

Accordingly, in order to create a more comfortable indoor environment, a method of removing contaminants has emerged by using photocatalytic photoactivity.

Meanwhile, as a representative material used as the photocatalyst, titanium dioxide, a semiconductor having a solid form, is mainly used. The electronic structure of the photocatalyst, such as titanium dioxide, is described as a band-theory, and the structure thereof. There is a forbidden energy band gap (Eg) between the valence band, which is the highest energy band filled by the electrons, and the electrons do not occupy, so that the electrons cannot occupy.

In particular, the solid form is mainly classified into a conductor, a semiconductor, and an insulator according to the electrical conductivity, which is basically the case where the electron is occupied by the electron occupancy mode of the energy band, and the electron can move freely in the energy band.

The electron-occupying aspects of the semiconductor and the insulator are basically the same, but are classified as insulators if they occupy a range of 0.3 to 3.5 eV depending on the size of the energy band gap, and are occupied in a higher range.

On the other hand, the semiconductor absorbs photons ( hv ≥Eg) having energy above the band gap to excite electrons from the shared band to the conduction band, and form holes in the sharing band to form electrons in the conduction band. In this case, semiconductors having a large band gap (3.0 to 3.2 eV), such as titanium dioxide, absorb only light having a short wavelength and do not absorb light in the visible light region, which occupies most of the solar energy. The photocatalyst shows only photoactivity at and does not show photocatalytic activity in the visible region.

Therefore, the titanium dioxide is very stable chemically and photochemically and its various uses are industrially produced in large quantities and is most widely used as a photocatalyst. However, as described above, the titanium dioxide does not exhibit photoactivity as a catalyst unless subjected to ultraviolet rays. .

In particular, since ultraviolet rays contain about 3 to 4% of sunlight, in order to photoactivate photocatalysts such as titanium dioxide, a light source that artificially emits ultraviolet rays must be separately provided. In view of the fact that only ultraviolet rays are emitted, there is a problem in that, in order to install and use a photocatalyst in a room, a light source for emitting ultraviolet rays must be separately provided to increase the efficiency of the photocatalyst.

Accordingly, the inventors of the present invention have shown that when nitrogen dioxide and chlorine ions are doped in titanium dioxide during the research to develop a photocatalyst coating sol exhibiting photoactivity in the visible region, the photoactive region exhibits photoactivity in the visible region. With this in mind, the present invention has been completed.

The present invention has been made to solve the above problems, and there is a technical problem to provide a method for producing a photocatalyst coating sol exhibiting photoactivity in the visible light region by reacting by mixing ammonia water, titanium tetrachloride and a solvent.

In addition, the present invention has a technical problem to provide a substrate coated with the above-described photocatalyst coating sol.

In one aspect, the present invention comprises the steps of mixing at 0.1 to 6% by weight of ammonia water, 1 to 10% by weight titanium tetrachloride and 84 to 98.9% by weight of the solvent at 0 to 20 ℃ per weight of the total mixture; Dispersing the mixture with an ultrasonic vibrator for 5 to 30 minutes; Aging the dispersed mixture at 70 to 100 ° C. for 2 hours; After cooling the mixture at the end of the aging step at room temperature and dialyzed until the pH 2 to 5 using a membrane for preparing a photocatalyst coating comprising the step of preparing titanium dioxide doped with colloidal nitrogen and chlorine ions Provided are methods for preparing the sol.

In another aspect, the present invention provides a substrate coated with a photocatalyst coating sol prepared according to a method for preparing a photocatalyst coating sol.

The photocatalyst coating sol according to the present invention includes titanium dioxide doped with nitrogen and chlorine ions, and preferably titanium dioxide in the form of colloidal nitrogen and chlorine ions, and the light in the visible region When irradiated, it exhibits photocatalytic activity.

Ammonia water (NH ₄ OH) according to the present invention is used to dope nitrogen ions to titanium dioxide contained in the photocatalyst coating sol, and any ammonia water commonly used in the art may be used. The amount used is preferably 0.1 to 6% by weight based on the total weight of the mixture.

Titanium tetrachloride (TiCl ₄ ) according to the present invention is used to form titanium dioxide constituting the photocatalyst coating sol and to dope chlorine ions into the formed titanium dioxide, and if titanium tetrachloride is commonly used in the art Any may be used, and the amount thereof is preferably used in an amount of 1 to 10% by weight based on the total weight of the mixture.

The solvent according to the present invention is for dissolving the ammonia water and titanium tetrachloride, and any solvent can be used as long as it can dissolve the ammonia water and titanium tetrachloride, but preferably water is used, more preferably. It is preferable to use distilled water, and the amount of use is preferably 84 to 98.9% by weight based on the total weight of the mixture.

Separation membrane according to the present invention is to adjust the pH to 2 to 5 by dialysis of the reactant prepared by the ammonia water, titanium tetrachloride and the solvent is aged, any separation membrane can be used as long as the dialysis membrane to control the pH Preferably, it is preferable to use an ion exchange membrane, and particularly preferably an ion exchange membrane having a molecular weight cut off (MWCO) of 6000 to 8000 Da.

Here, the separator is generally used in the same sense as the "membrane" or "exchange membrane", the separator according to the present invention may be referred to as the membrane or the exchange membrane.

Hereinafter, a method for preparing a photocatalyst coating sol according to the present invention will be described in detail.

First, 0.1 to 6% by weight of ammonia water and 1 to 10% by weight of titanium tetrachloride are added to 84 to 98.9% by weight of a solvent having a temperature of 0 to 20 ° C, and mixed.

Here, to prepare the titanium dioxide contained in the photocatalyst coating sol finally produced due to the aggregation of particles produced when the amount of the titanium tetrachloride exceeds 10% by weight or more, for example, to prepare an ultrafine particle size, for example 10nm or less. If the amount of the ammonia water added exceeds 6% by weight or more, the safety and the photocatalytic efficiency of the photocatalyst coating sol having a colloidal state decrease, so that the amount of the ammonia water is kept constant.

The mixture is then dispersed for 5-30 minutes with an ultrasonic vibrator, preferably an ultrasonic vibrator having about 40 KHz. In this case, for easy dispersion of the mixture, the mixture may be stirred for about 1 hour at room temperature using an stirrer before use of an ultrasonic vibrator as necessary.

The dispersed mixture is then aged for about 2 hours at a temperature in the range of 70 to 100 ° C.

In this case, the aging step is to increase the crystallization of titanium dioxide contained in the photocatalyst coating sol by heating the mixture solution, the aging time may be added or subtracted as needed.

The aged mixture is then cooled to room temperature and then dialyzed using a separator, preferably an ion exchange membrane, until the pH is 2 to 5 so that the nitrogen and chlorine ions in the colloidal state are doped into titanium dioxide.

At this time, the separator is to increase the stability of the solution by reducing the ionic strength (colloidal strength) of the colloid, any separator can be used as long as it is commonly used in the art.

On the other hand, the photocatalyst coating sol according to the present invention is used to coat the surface of the substrate for deodorization, antibacterial and organic decomposition, etc., if the method of coating the photocatalyst coating sol on the substrate is a method commonly used in the art Although any method may be used, Preferably spray method, gravure coating method, immersion method, etc. are used, Especially preferably, the spray method or immersion method is used.

Here, the term "substrate" is an object that can be used by coating the photocatalyst coating sol, for example, interior materials such as wallpaper, wood, glass, fiber and flooring materials, interior and exterior materials such as wall materials, antibacterial, deodorization, pollution prevention, etc. Various carriers requiring various effects, filters for water treatment or filters for air purification, for example, plastics such as metals, alloys, glass, metal meshes, ceramics, polypropylene, polyethylene terephthalate (PET), polyethylene, and nonwoven fabrics. Anything is OK.

Therefore, when the photocatalyst coating sol according to the present invention is used by coating the building interior and exterior materials and the filter for treating contaminants, the photocatalytic activity can be removed only by the light in the visible light region to remove harmful substances and contaminants.

In particular, the photocatalyst coating sol according to the present invention can be easily coated on the building interior and exterior materials, air purification filter, water treatment filter, etc. without using a separate binder and additives used in general coating sol, if necessary A pigment etc. can also be added and used.

Hereinafter, the present invention will be described in detail through examples. However, the following examples are only for illustrating the present invention in detail and are not intended to limit the scope of the present invention by these examples.

<Example>

As a solvent, 2% by weight of 28% aqueous ammonia solution and 2% by weight of titanium tetrachloride are added to 10 ° C of distilled water so that the total volume is 1L.

Then, the mixture was stirred for 1 hour while maintaining the temperature constant, and then dispersed for about 10 minutes by using an ultrasonic vibrator at about 40 KHz.

The dispersed coating was then aged at 80 ° C. for 2 hours, cooled at room temperature, and then the pH was adjusted to about 3 using a Spectra / Por Membrane: MWCO: 6-8000Da, Spectrum Laboratories Inc., USA. Dialysis until it is prepared to prepare a photocatalyst coating sol doped with nitrogen and chlorine ions.

In order to measure the light absorption of the photocatalyst coating sol, a UV-VIS spectrophotometer (DRS U-3501, Hitachi, Japan) was used, and the nitrogen and chlorine ions constituting the photocatalyst coating sol. The crystal structure of doped titanium dioxide was measured using XRD [Rigaku Mdel D / MAX-III B, Rigaku, Japan], surface area and pore size were measured by BET [ASAP 2010 Micro-metrics], particle size TEM [JEM-4010, JEOL, USA].

The results are shown in Table 1 and Figs. 1 and 2.

Table 1

Titanium Dioxide Properties of Photocatalyst Sol

Properties result Particle size (nm) <10 Specific surface area (m ² / g) 320 Pore diameter 23 Type Anatase

Comparative Example

3 wt% of Degusa-P25 [Degusa, Germany] per weight of the total photocatalyst coating sol was dispersed in 97 wt% of distilled water to prepare a photocatalyst coating sol, and the physical properties of the prepared photocatalyst coating sol were Same as the measuring method.

The results are shown in FIGS. 1 and 2.

As shown in Fig. 1 and 2, p25 constituting the photocatalyst coating sol according to the comparative example is light absorption only below 400nm, but doped with nitrogen and chlorine ions constituting the photocatalyst coating sol according to the embodiment Titanium dioxide was red-shifted to the visible light region, and it was confirmed that light absorption occurred at about 530 nm or less. In addition, the size of the titanium dioxide contained in the photocatalyst coating sol prepared according to the embodiment was less than 10nm, the pore size was found to have a specific surface area of 320m ² / g while having a mesopore pore of 20 to 30 ㅕ. Here, the red-shift means that the absorption wavelength band is moved to the visible light region.

Experimental Example

Photocatalytic Activity Experiment

In order to measure the photocatalytic activity of the photocatalyst coating sol prepared according to the embodiment in the visible light region, the photocatalyst coating sol prepared according to the embodiment and the photocatalyst coating sol prepared according to the comparative example were 1.5 cm ㅧ 2 cm in size. Each plate glass was coated by immersion method.

Then, after preparing two sealed quartz glass tubes having a volume of 130 cm ³ as a reaction tank, and installed a flat glass coated with a photocatalyst coating sol according to the embodiment to the bottom of one quartz glass tube, and another quartz glass tube To the photocatalyst coating sol was prepared according to the comparative example was installed flat glass.

Then, BLEDs (Blue-light-emitting diodes, Korea) emitting wavelengths of 427 nm were installed on the respective flat glass to emit light in the visible region.

Then, 830 ppm trichloroethylene (Trichloro ethylene, Aldrich, USA) gas was injected into each quartz glass tube to measure the degree of decomposition of the trichloroethylene.

Here, the experiment was performed while changing the intensity of the light source to BLED from ^{3.5V (122㎼ / cm 2 at 472nm} ) 5.5V (164㎼ / cm 2 at 472 nm).

At this time, the concentration of the trichloroethylene was measured using an FT-IR spectrometer [SPECTRUM 1, Perkin Elmer, UK], the results are shown in FIG.

3, the initial 270 minutes to ^{3.5V (122㎼ / cm 2 at 472nm} ) to increase the intensity of light in a train proceeding to photochemistry ^{5.5V (164㎼ / cm 2 at 472} nm) after that As a result, the slide glass plate coated with the photocatalyst coating sol prepared according to the embodiment was observed to increase the photochemical reaction rate depending on the light intensity, but the photocatalyst coating sol prepared according to the comparative example. In the case of the coated slide glass, no photochemical reaction occurs in the visible light irrespective of the light intensity.

Meanwhile, the change in the reaction rate according to the light intensity of the BLED indicates that the reaction proceeds only by pure visible photochemical reactions without the influence of adsorption.

As described above, those skilled in the art will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. Therefore, the exemplary embodiments described above are to be understood as illustrative in all respects and not as restrictive. The scope of the present invention should be construed that all changes or modifications derived from the meaning and scope of the appended claims and their equivalents, rather than the detailed description, are included in the scope of the present invention.

The photocatalyst coating sol prepared according to the method for preparing a photocatalyst coating sol according to the present invention has an effect of showing photocatalytic activity in the visible light region by doping titanium dioxide with chlorine ions.

In addition, the manufacturing method of the photocatalyst coating sol according to the present invention has an effect that it is easier than the conventional manufacturing method of the photocatalyst coating sol by manufacturing according to the wet manufacturing method that does not require a high temperature sourcing process.

In addition, the photocatalyst coating sol according to the present invention is coated on not only indoor interior materials such as wallpaper, blinds and painted cement, but also on air purification and air conditioning filters and water treatment filters to remove odors, harmful substances and harmful bacteria from visible light sources. It can work.

Claims (5)

Mixing from 0.1 to 6% by weight of ammonia water, from 1 to 10% by weight of titanium tetrachloride and from 84 to 98.9% by weight of the solvent at 0 to 20 ° C. per weight of the total mixture; Dispersing the mixture with an ultrasonic vibrator for 5 to 30 minutes; Aging the dispersed mixture at 70 to 100 ° C. for 2 hours; After the aging step is cooled to room temperature and then dialyzed until the pH 2 to 5 using a dialysis membrane to adjust the pH to control the pH to prepare a titanium dioxide doped with colloidal nitrogen and chlorine ions Method for producing a photocatalyst coating sol comprising the step. The method of claim 1, Method for producing a photocatalyst coating sol, characterized in that the separator is an ion exchange membrane. Building interior and exterior materials coated with a photocatalyst coating sol prepared by the manufacturing method according to claim 1 or 2. delete A filter coated with a sol for coating a photocatalyst prepared by the manufacturing method according to claim 1.

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