KR100337979B1 - A preparation of titanium dioxide film by sol-gel method for the removal of indoors harmful gases - Google Patents

Abstract

The present invention relates to the production of a titanium dioxide membrane for effectively removing the harmful indoor gases frequently generated in homes, offices, and industrial sites, and more particularly, to a titanium dioxide membrane for removing trichlorethylene and aldehydes in the indoor harmful gases. It relates to the development of a photocatalytic reactor. The present invention relates to the production of titanium dioxide by the sol-gel method and to immobilization of titanium dioxide in a glass reactor.

Description

A preparation of titanium dioxide film by sol-gel method for the removal of indoors harmful gases}

The present invention relates to the production of a titanium dioxide membrane for effectively removing the harmful indoor gases frequently generated in homes, offices, and industrial sites, and more particularly, to a titanium dioxide membrane for removing trichlorethylene and aldehydes in the indoor harmful gases. It relates to the development of a photocatalytic reactor.

Today, as the industry develops, millions of chemicals are used and are under development. Among them, there are about 500,000 kinds of odor-causing substances and about 10,000 kinds are classified as odorous substances. These odor-causing substances are harmful to human health and cause a lot of mental damage. Typical examples are industrial sites using various solvents, odors in automobiles, various chemicals present in laboratories, as well as the smell of kitchens and toilets at home.

As a method of removing the harmful gases, many methods such as incineration, adsorption, cooling condensation, and bio-filtration have been studied. The adsorption method is a method of adsorption, recovery or removal of harmful gas substances by using an adsorbent such as activated carbon, which removes harmful gas substances having a concentration of 25% or more, and when installation costs are low and the harmful gas substances adsorbed on activated carbon are expensive. The operating cost can be reduced in recovery. However, harmful gas substances such as ketones, aldehydes, or esters tend to polymerize on the surface of activated carbon to prevent fine pores of activated carbon, thereby degrading the adsorption function, and treatment of wastes generated through adsorption is a problem. . It is also unsuitable for processes with large flow rates because of its smaller capacity compared to existing hazardous gas treatment methods. The incineration method has a direct combustion method and a catalytic combustion method, and the direct combustion method has the advantage of treating a large amount of harmful gas substances by directly burning and removing the harmful gas substances at a high temperature of 700 to 1000 ° C. However, if the load fluctuates severely, or the concentration is low and the flow rate is low, it is uneconomical. The system is relatively large, and the installation area is large, which makes it difficult to expand the equipment. The operation temperature is relatively high due to the high reaction temperature, and secondary air pollutants such as NOx and dioxin may be generated depending on the reaction conditions.

The catalytic combustion method is a method of burning and removing harmful gas substances generated from a fixed source by using a catalyst, and the catalytic combustion method can be effectively removed at lower reaction temperatures than the direct combustion method. Therefore, it is economical because the fuel cost is low because the reaction temperature is low, and the system is simple and the equipment is easy to expand. However, as a catalyst for removing harmful gas substances developed so far, precious metal catalysts such as Pt, Pd, and Rh, and expensive catalysts such as Cr, Co, Ni, Mn, and Fe are used. However, these catalysts have problems in terms of cost and endothelial toxicity, and thus, new catalysts need to be developed. In addition, the actual VOC material is emitted as a mixed gas mixed with various components rather than exist in a single phase. In addition, such a catalytic reaction reacts at a high temperature and shows many problems in actual commercialization.

And cooling condensation and bio-filtration methods are limited in their efficiency. Therefore, in recent years, photocatalytic methods for removing harmful gas substances by irradiating appropriate light to semiconductors to remove organic substances as a method for effectively and economically removing organic compounds have attracted attention.

Hazardous gas treatment technology using photocatalyst is a method of decomposing organic materials by coating titanium dioxide and activated carbon with high adsorption power on glass that is well exposed to sunlight, and adsorbing harmful gases even when there is no sunlight. It can be said to be an efficient process that can be removed. In addition, the use of a photocatalyst has the advantage of being semi-permanent and having little maintenance, so it is economical and there is no fear of secondary pollution.

It is known to cause photocatalytic action when light is irradiated to a semiconductor material. Among them, titanium dioxide has a very strong photocatalytic action. This reactivity can effectively remove indoor harmful gases. The photocatalytic reaction is described in detail as a complex photochemical surface reaction caused by cleavage of chemical bonds on the surface of titanium dioxide, formation of lattice defects and adsorption of oxygen molecules in the atmosphere. These reactions must be ultra-fine particles with light wavelength below 400nm and have a large specific surface area.

On the other hand, in the conventional method, when titanium dioxide is used in a powder state, it can fly even in a fine air flow and act as a particulate matter floating in the air, thus becoming a new air pollutant. Therefore, a technique for effectively attaching and immobilizing titanium dioxide on a glass film is required. In addition, the activity of the photocatalytic reaction should be high at the same time.

Accordingly, an object of the present invention relates to the production of a titanium dioxide membrane for effectively removing the indoor harmful gases frequently generated in homes, offices and industrial sites, and more particularly to the removal of trichlorethylene and aldehydes in indoor harmful gases. The present invention relates to the development of a photocatalytic reactor equipped with a titanium film.

The object of the invention described above is achieved by a titanium dioxide photocatalyst immobilized on a glass reactor.

Hereinafter, the present invention will be described in detail.

To prepare a titanium dioxide sol, titanium isopropoxide is first added to five times ethanol in a molar ratio and then slowly dissolved in a high speed stirrer. At this time, distilled water and hydrochloric acid are mixed slowly. The dropping time of distilled water was performed for 10 to 120 minutes, depending on the ratio of water / titanium isopropoxide, for 60 minutes or more for hydrochloric acid and for about 30 minutes for titanium isopropoxide. The mixed solution was mixed in a high speed stirrer for about 5 to 6 hours, washed and filtered, and then dried at 80 ° C. for 24 to 36 hours to obtain titanium dioxide powder. The dried titanium dioxide powder was calcined for at least 2 hours in a high temperature electric furnace at 400 ° C or higher.

Moreover, the method to fix to a glass reactor is demonstrated.

To immobilize the photoreactor, titanium dioxide was first mixed with an appropriate amount of ethyl alcohol to make a suspension. This titanium dioxide suspension was brought into uniform contact with the inner wall of the outer tube of the photoreactor and the outer wall of the inner tube. The photoreactor in contact with the titanium dioxide suspension was placed in a drier and dried at 120 ° C. for 1 hour. This process was repeated several times until the desired mass of titanium dioxide was immobilized. And finally, it was calcined in an air atmosphere at 400 ° C. for 1 hour at a temperature range in which the crystal structure of anatase of titanium dioxide did not change, thereby minimizing the influence of impurities other than titanium dioxide. .

The reactor prepared as described above is a double tube reactor made of Pyrex, the total length of the reactor is 300mm, the outer diameter of the outer tube is 25mm, the inner diameter is 20mm, the thickness of the tube is 2.5mm, the outer diameter of the inner tube Is 16mm, the inner diameter is 13mm, the tube thickness is 1.5mm and the volume is about 34ml. There is a narrow gap of about 2 mm between the inner wall of the reactor and the outer wall of the inner tube so that when harmful gas flows between the outer and inner walls of the inner tube, Designed to contact

An 8W black light lamp was used as the light source irradiated to the reactor, and experiments were carried out by installing one to three lamps around the reactor. The maximum wavelength of this lamp is 365nm. Due to the heat from the lamp, the temperature of the reactor was maintained at about 50 ± 2 ℃, and the experiment was carried out in a dark box manufactured by the reactor to minimize the influence of other light energy such as sunlight.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

The reactor was irradiated with an ultraviolet lamp while passing 22,860 ppm of trichlorethylene and air at a flow rate of 50 ml / min. After light irradiation, the concentration of trichlorethylene began to decrease rapidly, and after about 10 minutes, the concentration decreased to 100 ppm or less.

Comparative Example 1

The same experiment was carried out in a glass reactor in which titanium dioxide was not immobilized under the same conditions as in Example 1, and the concentration of trichlorethylene hardly decreased, and the concentration was maintained at approximately 22,000 ppm even after 24 hours of reaction.

Example 2

The reactor was irradiated with an ultraviolet lamp while passing 22,860 ppm of trichlorethylene, 9,047 ppm of water and air at a flow rate of 50 ml / min to a reactor immobilized with 0.5 g of titanium dioxide prepared in the reactor. After irradiation of light, the concentration of trichlorethylene began to decrease rapidly, and after about 5 minutes, the concentration decreased to 200 ppm or less.

Comparative Example 2

The reactor was irradiated with an ultraviolet lamp while passing 22,860 ppm of trichlorethylene, 9,047 ppm of water, and air at a flow rate of 50 ml / min to a reactor immobilized with 0.5 g of commercially available anatase type titanium dioxide. After irradiation of light, the concentration of trichlorethylene decreased, but even after 24 hours, the concentration remained almost 10,000 ppm.

Example 3

The reactor was irradiated with an ultraviolet lamp while passing 2,450 ppm of acetaldehyde, 9,047 ppm of water and air at a flow rate of 50 ml / min to a reactor immobilized with 0.5 g of titanium dioxide prepared according to the present invention. After light irradiation, the concentration of trichlorethylene began to decrease rapidly, and after about 10 minutes, the concentration decreased to 10 ppm or less.

Comparative Example 3

The same experiment was carried out in a glass reactor in which titanium dioxide was not immobilized under the same conditions as in Example 1, and the concentration of acetaldehyde was hardly reduced, and the concentration was maintained at about 2,400 ppm even after 24 hours of reaction.

When using the photocatalyst in which the titanium dioxide prepared by the sol-gel method is immobilized in the glass reactor, the case of the embodiment and the comparative example in which the titanium dioxide is immobilized or the commercially available anatase type titanium dioxide are immobilized will be described. If not, almost no trichlorethylene or acetaldehyde was decomposed, while the trichlorethylene or acetaldehyde was decomposed within 10 minutes in the sol-gel-titanium-immobilized reactor.

As described above, the present invention relates to the production of a titanium dioxide membrane for effectively removing the indoor harmful gases frequently generated in homes, offices and industrial sites.

Claims (1)

Titanium dioxide prepared by the sol-gel method is immobilized in a glass reactor to deodorize indoor harmful gases