JP2838601B2 - Odor gas adsorbent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION This invention relates to odorous gas adsorbents and, more particularly, to silicates and silver, aluminum, titanium, vanadium, chromium, manganese,
Iron, cobalt, nickel, tin, copper, zinc, cadmium,
It is an adsorbent which is mainly composed of a gel containing one or more kinds of metal salts of lead and has excellent adsorptivity for bad odor gases such as hydrogen sulfide, ammonia, mercaptan, amine and aldehyde.

[0002]

2. Description of the Related Art In recent years, trace amounts of hydrogen sulfide, ammonia, mercaptan,
There is increasing interest in odorous gases such as amines and aldehydes. In order to remove these odorous gases and maintain a comfortable living environment, a deodorant is required, and various odorous gas adsorbents are used in home life.

[0003] Since these malodorous gas adsorbents are used in daily life, they are required to satisfy the following conditions.

(1) It should have excellent deodorizing performance against various odorous gases such as hydrogen sulfide, ammonia, mercaptan, amine and aldehyde which are present in daily living space. (2) High safety.
(3) It should be easy to handle. (4) Be inexpensive.

However, heretofore, there has been no odorous gas adsorbent which sufficiently satisfies all the above conditions. Activated carbon has an excellent deodorizing effect on malodorous gases such as mercaptans and amines, but does not have a very high effect on deodorizing hydrogen sulfide and ammonia, which are trace amounts of malodorous gas in daily living space. For the purpose of improving this point, a product called impregnated carbon in which acid, alkali or a certain halogen compound is supported on activated carbon has been produced. However, products that have undergone such treatment must be handled as a kind of dangerous substance, as is the case with acids or alkalis, and thus are often unsuitable for use in daily life.

[0006] Products obtained by adding ascorbic acid to iron sulfate are also commercially available. This type has a good deodorizing effect on basic malodorous gases such as ammonia and amines, but has little deodorizing effect on hydrogen sulfide, mercaptan and aldehydes, and dissolves when wet with water. There is a drawback that cannot be used for deodorization.

Although many other chemical deodorants have been disclosed, many of them have strong acidity or alkalinity, and the types of gases that can be removed are limited, and some have a disadvantage that they are easily affected by moisture absorption or drying. Many.

In addition, there are organic deodorants, but they have low heat resistance, are difficult to process, and are expensive.

[0009]

SUMMARY OF THE INVENTION The present invention is aimed at removing trace amounts of malodorous components present in daily living space, and particularly has a problem with malodorous gases such as hydrogen sulfide, ammonia, mercaptan, amine and aldehyde. An object of the present invention is to provide a novel odor gas adsorbent having a new composition, which has an excellent deodorizing effect, is safe and easy to handle.

[0010]

Means for Solving the Problems In order to achieve the above object, the present inventors have eagerly studied the relationship between the silicate gel formation process and the specific surface area and the adsorptivity when a zinc compound is included in the gel. As a result of repeated research, they found that a gel composition having excellent adsorption performance for malodorous gases such as hydrogen sulfide, ammonia, mercaptan, amine and aldehyde was present, and based on this, a silicate containing a zinc compound was included. Application for gel deodorant (Japanese Patent Application No. Hei 3-
No. 25295). Furthermore, as a result of studying silicate gels containing other metal salts and silicate gels containing these metal salts in the presence of zinc salts, hydrogen sulfide, ammonia, mercaptans, amines, aldehydes, etc. They have found that they have excellent deodorizing performance, and based on this they have reached the present invention.

That is, one or two selected from the group consisting of silicates and metal salts of silver, aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, tin, copper, zinc, cadmium and lead. After adjusting the pH of the aqueous solution containing the metal salt to 9 to 11 and maintaining the solution at 45 to 70 ° C. to produce a sol containing a silicate and a metal salt, the solution is neutralized with an acid to obtain a specific surface area. It is a malodorous gas adsorbent obtained by incorporating a metal salt inside a silica gel structure of 500 m ² / g or more.

Hereinafter, the present invention will be described in detail. Here, the silicates include not only salts of silicic acid but also silicic acid, silicic anhydride and the like generated in the process of forming silicic acid gel.

The deodorant of the present invention is a composition having a silicate gel structure comprising a silicate and a metal salt. Although a wide range of silicates can be used as the raw material of the deodorant of the present invention, for example, water glass, silicon hydroxide, silica sol, silica gel and the like which are dissolved in an alkaline aqueous solution are preferable.

The metal salt of the present invention is one or more metals selected from the group consisting of silver, aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, tin, copper, zinc, cadmium and lead. It is necessary to use salt. The type of salt is not particularly limited, and a wide variety of salts can be used, but sulfates, chlorides, nitrates,
Acetates and the like are preferred.

Although the content of the metal salt is not particularly limited, the weight ratio of the silicate (a) (in terms of SiO ₂ ) and the metal salt (b) (in terms of metal) is (a) :( b) = 5: 1 to 1 20: 1 is preferred. Even if the ratio of the metal salt is higher than this, the adsorptivity does not improve much. If the metal salt content is lower than this, the adsorptivity of the offensive odor substance is undesirably reduced.

To adjust the pH of the aqueous solution of the silicate and the metal salt, an alkaline compound such as sodium hydroxide, calcium hydroxide, barium hydroxide, ammonia or the like can be used. To neutralize the alkaline aqueous solution, an acid such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid and the like can be used. However, an alkaline compound or acid that produces a water-insoluble salt during the adjustment or neutralization of the pH is not preferred.

In the method for preparing the adsorbent of the present invention, it is necessary to dissolve a silicate and a zinc compound in an alkaline aqueous solution, adjust the pH to 9 to 11, and keep the solution at 50 to 70 ° C. By maintaining the solution under such conditions, the silicic acid molecules in the solution gradually polymerize to form polysilicic acid molecules. At that time, metal atoms contained in most metal salts are replaced with silicon atoms in the polysilicic acid molecule. Therefore, the polysilicic acid molecule serving as the skeleton of the sol generated in the solution has a structure in which some silicon atoms in the silicate molecule are substituted with metal atoms.
Further, it is considered that some metal atoms not substituted with silicon atoms are included in the sol in the form of metal salts.

At this time, the pH and temperature of the solution are closely related to the composition and structure of the sol to be produced, and further, have a very large influence on the fine structure such as the specific surface area, pore volume, and pore distribution of the adsorbent of the present invention. Having. Since the hydroxyl group contained in the solution serves as a catalyst for the polymerization of silicic acid molecules, if the pH is lower than 9, the polymerization does not proceed because the concentration of the hydroxyl group serving as a catalyst is low, that is, the sol does not grow. Therefore, even if the gel is precipitated by neutralizing the solution and dried to prepare an adsorbent, the specific surface area is small because the pore structure is not developed, and the deodorizing property is low, so that the practicality is poor.

On the other hand, when the pH is higher than 11, polymerization is inhibited, and the sol formation rate is significantly reduced. This is considered to be due to an increase in the charge of the polysilicic acid molecules and an increase in the repulsion of the molecules due to an increase in the hydroxyl group concentration.

When the solution temperature is 70 ° C. or higher, the polymerization rate is increased, and the sol formed in the solution has a sparse structure, so that the specific surface area of the deodorant is reduced and the odor adsorbing ability is reduced. When the temperature is lower than 50 ° C., the polymerization rate becomes slow, and the sol formed in the solution has a dense structure, almost no pores are formed, and therefore the specific surface area becomes very small, so that the adsorptivity decreases. It cannot be used as a deodorant.

When the sol is formed while maintaining the solution within the above range, the time is not particularly limited, but may be from 10 to 60.
Of the order of minutes. The metal salt dissolved in the liquid due to the growth of the sol is in a state of being included in the sol.

Next, by neutralizing the solution, the silica sol containing the metal salt undergoes a phase transition to a gel and precipitates. The pH at the time of neutralization is not particularly limited, but is preferably in the range of 6 to 7.
The adsorbent of the present invention is obtained by filtering and drying the precipitated gel.

The specific surface area of the thus obtained gel having a porous structure must be 500 m ² / g or more. When the specific surface area is reduced to 500 m ² / g or less, the adsorptivity to odorous gas is significantly reduced. This is due to the decrease in specific surface area.
It is considered that the physical adsorbability decreases.

The adsorbent comprising a silicate and a metal salt according to the present invention exhibits good adsorptivity up to around 500 ° C. and has excellent thermal stability.

[0025]

The odorous gas adsorbent of the present invention has a pore structure and a specific surface area of 600 to 700 m ² / g. It comprises polysilicic acid gel and one or more metal atoms or metal salts contained therein. Has become. Therefore, it is considered that a high adsorptivity against malodor is exhibited due to a synergistic effect of the physical adsorption of the silica gel and the chemical actions of the metal atoms and some metal salts contained in the polysilicic acid molecules.

Further, since the metal atoms and metal salts are contained in the polysilicate gel structure in such a state, they do not elute to the outside even when they come into contact with water or acid, and the safety is high.

[0027]

The present invention will be described more specifically with reference to the following examples.

(Example 1) Pure water 1 was placed in a 2-liter beaker.
One liter, 270 g of water glass, 25 g of zinc sulfate and 507 g of aluminum sulfate were added, the pH was adjusted to 10 with a sodium hydroxide solution, and the mixture was stirred to form a uniform solution, which was then aged at 50 ° C. for 20 minutes. Next, 40% sulfuric acid was added with stirring to adjust the pH to 7.1, and the product was filtered, washed, and dried at 200 ° C. for 3 hours to prepare a silicate and zinc sulfate adsorbent of the present invention. The specific surface area of this adsorbent is 53 (Brunauer, Emmett & Teller).
It was 0 m ² / g.

The adsorptivity of this adsorbent for malodorous gases such as hydrogen sulfide, ammonia, methyl mercaptan, sulfur dioxide and aldehyde was examined as follows. Sorbent 100mg
Into a vial with an internal volume of 120 ml, and after closing the rubber stopper,
A predetermined amount of malodorous gas component is injected into the vial using microsilidine. Two hours after the gas was injected, the air in the vial was taken out with microsilidine, and the gas concentration was analyzed using a gas chromatograph.

The results are shown in Table 1. In addition, since the metal atom in the metal salt added to the solution is mostly replaced by the silicic acid molecule in the polysilicic acid molecule skeleton, the content is shown in terms of the metal element.

[0031]

[Table 1]

(Comparative Examples 1 to 4) As shown in Table 1, four kinds of adsorbents were obtained by changing the aging conditions at the same compounding ratio as in Example 1. Table 1 shows the BET specific surface area of the adsorbent and the adsorptivity to various odorous gases.

(Examples 2 to 4) By the same method as in Example 1, an adsorbent having a composition as shown in Table 2 and containing a metal salt was obtained. Table 2 shows the weight ratio of the silicate to the metal compound and the adsorptivity to various malodorous gases by chemical analysis of these adsorbents.

[0034]

[Table 2]

[0035]

The odor gas adsorbent comprising a silicate and a metal salt according to the present invention has excellent adsorptivity to various odor gases such as hydrogen sulfide, ammonia, mercaptan, amine and aldehyde which are present in daily living space. Have. Furthermore,
It is composed of a non-toxic silicate compound, and since the metal salt is contained in the inside of the silicate gel, it does not elute to the outside, so that it has high safety and can be used for many applications.

The fine powder can be easily carried on paper and sheets, and is thermally stable up to about 500 ° C. For this reason, it is excellent in processability, such as being able to inject into plastics, and has high industrial applicability as an adsorbent.

Claims (1)

(57) [Claims] 1. One or two kinds selected from the group consisting of silicates and metal salts of silver, aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, tin, copper, zinc, cadmium and lead. After adjusting the pH of the aqueous solution containing the metal salt to 9 to 11 and maintaining the solution at 45 to 70 ° C. to produce a sol containing a silicate and a metal salt, the solution is neutralized with an acid to obtain a specific surface area. An odorous gas adsorbent that contains metal salts inside a silica gel structure of 500 m ² / g or more.