JPH04349934A - Inorganic adsorbent - Google Patents

Abstract

PURPOSE:To improve the safety of an inorganic adsorbent comprising silicate, zinc compound, and active carbon in which the active carbon particles are dispersed uniformly, by preparing the adsorbent in the form of powder or spherical particles. CONSTITUTION:An adsorbent comprizing silicate, zinc compound, and active carbon is characterized not only by an excellent power of deodorizing various gasses with offsensive odor existing in a daily life environment such as hydrogen sulfide, ammonia, mercaptan, amine, and aldehyde but also by a high level safety due to its harmless composition of silicate, zinc compound, and active carbon. Since the adsorbent can be prepared in the form of fine powder, it is mixed easily into paper and sheets. Its thermal stability at up to about 500 deg.C enables mixing into plastic and affords a good processability. The adsorbent of spherical particles is easy in handling and can be used in wide applications.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an adsorbent, and more specifically, it relates to an adsorbent for hydrogen sulfide, ammonia,
It has excellent properties for adsorption and removal of malodorous components such as mercaptans, amines, and aldehydes.

0002

BACKGROUND OF THE INVENTION In recent years, various malodorous gases such as hydrogen sulfide, ammonia, mercaptans, amines, and aldehydes that exist in daily living spaces have become a problem. For this reason, in order to maintain a comfortable living environment, there is growing social interest in deodorizers that have the ability to remove these foul-smelling gases.
Various types of deodorizers are used.

[0003] Since these deodorizing agents are used in daily life, they are required to satisfy at least the following conditions.

[004] (1) It must have good deodorizing performance against various malodorous gases present in everyday living spaces. (2) It must be highly safe. (3) It must be easy to handle. (4) It must be inexpensive.

[0005] Conventionally, however, there has been no deodorizing agent that fully satisfies all of the above conditions. Although activated carbon has an excellent deodorizing effect on malodorous gases such as mercaptans and amines, it is not very effective in deodorizing hydrogen sulfide and ammonia, which are typical malodorous gases present in everyday living spaces. In order to improve this point, a product called impregnated carbon, in which activated carbon is loaded with acid, alkali, or some kind of halogen compound, is also produced. However, products that have undergone such treatment must be treated as a type of dangerous substance, similar to acids or alkalis themselves, and are therefore often unsuitable for use in daily life.

[0006] Products containing iron sulfate and ascorbic acid are also commercially available. This type of product has a good deodorizing effect on basic foul-smelling gases such as ammonia and amines, but it has almost no deodorizing effect on hydrogen sulfide, mercaptans, aldehydes, etc., and it dissolves when wet with water, so it is a wet gas. The disadvantage is that it cannot be used for deodorizing.

Although many other chemical deodorizing agents have been disclosed, many of them are strongly acidic or alkaline, the types of gases that can be deodorized are limited, and they have drawbacks such as being susceptible to moisture absorption or drying.

There are other organic deodorizing agents, but they have low heat resistance, are difficult to process, and are expensive.

[0009]

[Problems to be Solved by the Invention] The present invention is aimed at removing malodorous components present in daily living spaces, and is particularly aimed at removing malodorous gases such as hydrogen sulfide, ammonia, mercaptans, amines, and aldehydes. The object of the present invention is to provide a deodorizing agent having a completely new composition, which has a good deodorizing effect, is highly safe, and is easy to handle.

0010

[Means for Solving the Problems] In order to achieve the above-mentioned objects, the present invention has conducted intensive research on three-component compositions of silicates, zinc compounds, and activated carbon. The inventors have discovered that there are compositions that have excellent deodorizing performance against malodorous gases such as aldehydes and aldehydes, and have arrived at the present invention based on this finding.

That is, the specific gravity of an inorganic adsorbent made of particles made of a silicate, a zinc compound, and activated carbon, with the activated carbon particles uniformly dispersed therein, and an aqueous solution containing a mixture of the silicate and the zinc compound is 1.5. Adjust to ~2.5,
After adding activated carbon particles and mixing, the mixed liquid is dropped into a coagulation bath consisting of two layers: a hydrophobic liquid at the top and a coagulation liquid at the bottom to coagulate spherical particles consisting of silicate, zinc compound, and activated carbon. This is a method for producing an inorganic adsorbent comprising a silicate, a zinc compound, and activated carbon.

The present invention will be explained in detail below.

The adsorbent of the present invention is a particle consisting of a silicate, a zinc compound and activated carbon. The silicate used in the present invention is not particularly limited and a wide range of silicates can be used, but water glass, silicon hydroxide, silica sol, silica gel and the like are preferred. The zinc compound is also not particularly limited, but preferred examples include zinc sulfate, zinc chloride, zinc nitrate, and zinc acetate.

Various activated carbons such as coconut shell, coal, phenol, PAN (polyacrylonitrile), and pitch can be used as the activated carbon, and they can be in the form of granules, fibers, or
Powdered activated carbon can also be used, but fine particles are most preferred for uniform dispersion within the composition.

The properties of the silicate and zinc compound inside the adsorbent particles of the present invention are not particularly limited, but the state in which the silicate is in the form of a gel exhibits the highest adsorptivity. Activated carbon must be uniformly dispersed inside the gel particles. If activated carbon is unevenly distributed, activated carbon and silicates,
The adsorption properties are similar to those in the state where the zinc compound gel exists separately, and no synergistic effect between the two is observed. Therefore, in order to enhance the adsorption properties of the adsorbent of the present invention, it is necessary to use as fine particles of activated carbon as possible and to uniformly disperse them inside the gel particles.

To prepare the adsorbent of the present invention, a silicate and a zinc compound are made into an aqueous solution with a pH around 10, activated carbon is added, and the pH is adjusted to 2 to 7, preferably 2 to 5, with an acid while stirring. The silicate and zinc compound in the aqueous solution coagulate to form a precipitate in which zinc and activated carbon are dispersed inside the gel-like silicic acid. Next, this precipitate is separated from the liquid and then dried to obtain a finely powdered adsorbent of the present invention. Alkali and acids are used to adjust the pH of the solution. Alkaline compounds include sodium hydroxide, calcium hydroxide, barium hydroxide, ammonia, etc., while acids include hydrochloric acid, sulfuric acid, nitric acid, acetic acid, etc. can be used. However, if the zinc compound is a sulfate, using calcium hydroxide or barium hydroxide as an alkaline compound for pH adjustment will produce water-insoluble salts, so it is necessary to select an alkaline compound that does not produce insoluble salts. be.

Similarly, when calcium hydroxide or barium hydroxide is used as an alkaline compound for pH adjustment, P
Use of sulfuric acid as the acid for H adjustment is undesirable because a water-insoluble salt is produced. It is necessary to choose an alkaline compound that does not form insoluble salts.

Furthermore, as a method for manufacturing the adsorbent of the present invention into spherical particles, a silicate and a zinc compound are made into an aqueous solution at pH 9 to 11, activated carbon is added, and the pH is adjusted to pH 6 to 9 with acid while stirring.
Preferably, after adjusting the pH to 7 to 8, it is dropped into a coagulation bath consisting of two layers, in which a hydrophobic liquid is present in the upper layer and a coagulating liquid adjusted to pH 6 to 8 is present in the lower layer, and the upper layer is in a hydrophobic liquid. Spherical particles are generated by the surface tension of the dropped liquid, which is then coagulated in the underlying coagulation liquid to obtain spherical adsorbent particles.

Here, the hydrophobic liquid is a liquid compound insoluble in water, such as higher hydrocarbons, esters, benzene, higher alcohols, and kerosene. Further, the coagulating liquid is an aqueous solution prepared to have a pH of 6 to 8, and is a liquid that easily coagulates and gels when the silicate solution is dropped.

At this time, the specific gravity of the aqueous solution of the silicate and zinc compound is 1.5 to 2.5, preferably 1.5 to 2.2.
, more preferably 1.8 to 2.0. This is because when activated carbon is added to an aqueous solution of silicate and zinc compounds, separation may occur due to the difference in specific gravity.If the specific gravity of the solution decreases below 1.8, the activated carbon will settle, and if the specific gravity decreases to 2. If it is higher than 5, it will float. Therefore, the activated carbon particles are not uniformly dispersed inside the adsorbent and are unevenly distributed, resulting in a decrease in adsorption performance and particle strength.

Furthermore, in order to obtain uniform adsorbent particles,
The temperature of the coagulation bath is preferably 50-70°C, more preferably 55-65°C.

The composition of the silicate, zinc compound and activated carbon in the adsorbent of the present invention has a considerably high adsorption performance at any ratio, but when the ratio of the zinc compound and activated carbon is 1 to 5 parts by weight of the silicate, respectively. A composition within the range of ˜4 is more preferable. That is, the particles obtained by drying the precipitate produced in a region where the weight ratio of zinc compound to activated carbon is more than 4:1, or a composition region where the ratio of activated carbon is more than 1:4, are:
Each exhibits almost the same adsorption properties as the single component zinc compound or activated carbon, and it is recognized that these adsorption properties have a poor synergistic effect compared to the adsorption properties of spherical particles obtained in the composition range of the present invention.

[0023]

[Examples] The present invention will be explained in more detail with reference to Examples below.

(Example 1) Pure water 1 in a 2 liter beaker
Add 60 g of water glass and 224 g of Zn(OH), adjust the pH to 10 with NaOH, stir to make a homogeneous solution, then add 6 g of activated carbon powder and stir again until the solution reaches 40%
The pH was adjusted to 7.3 by adding H2SO4, and the mixture was left at room temperature for 4 hours.

After filtering and washing the product, it was dried at 200° C. for 3 hours to prepare the silicate, zinc compound, and activated carbon-based adsorbent of the present invention. The BET specific surface area of this deodorizer is 610
m2/g, and chemical analysis revealed that the weight ratio of silicate to zinc compound to activated carbon was 5:4:1.

The adsorption properties of this adsorbent for malodorous gases such as hydrogen sulfide, ammonia, mercaptans, amines and aldehydes were measured as follows.

[0027] 100mg of adsorbent with an internal volume of 120ml
After placing the sample in a glass vial and sealing it with a rubber stopper, a predetermined amount of the malodorous gas component is injected into the vial using a microsyringe. Two hours after injecting the gas, the air inside the vial is extracted using microsilidine, and the gas concentration is analyzed using a gas chromatograph.

The results are shown in Table 1.

(Examples 2 to 4) Adsorbents were obtained in exactly the same manner as in Example 1, except that the quantitative ratios of the zinc compound and activated carbon were varied. Table 1 shows the weight ratio of silicate, zinc compound, and activated carbon, as well as the adsorption characteristics for various malodorous gases, as determined by chemical analysis of these adsorbents.

(Comparative Examples 1 to 3) Adsorbents were obtained in exactly the same manner as in Example 1, except that the ratios of silicate, zinc compound, and activated carbon were varied. The BRT specific surface areas of Comparative Examples 1, 2, and 3 are 470, 800, and 580 m2/
It was g. Table 1 shows the adsorption characteristics for various malodorous gases.

(Comparative Example 4) Table 1 shows the adsorption properties of commercially available activated carbon for various malodorous gases.

(Example 1) 1 liter of pure water in a 2 liter beaker
Add 60 g of water glass and 224 g of Zn(OH), adjust the pH to 10 with NaOH, stir to make a homogeneous solution, then add 12 g of activated carbon powder and stir again until the solution reaches 40%
After adjusting the pH to 7.3 by adding H2SO4, the spherical particles were added dropwise to a coagulation bath consisting of two layers: kerosene in the upper layer and coagulation liquid of a dilute sulfuric acid solution with a pH of 6.8 in the lower layer. The spherical particles were coagulated in the coagulation liquid in the lower layer.

After filtering and washing the product, it was dried at 200° C. for 3 hours to prepare the silicate, zinc compound, and activated carbon-based adsorbent of the present invention. The BET specific surface area of this deodorizer is 580
m2/g, and chemical analysis revealed that the weight ratio of silicate to zinc compound to activated carbon was 5:4:2.

The adsorption properties of this adsorbent for malodorous gases such as hydrogen sulfide, ammonia, mercaptans, amines and aldehydes were measured and the results are shown in Table 1.

[0035]

[Table 1]

[0036]

Effects of the Invention: The silicate, zinc compound, and activated carbon-based adsorbent of the present invention exhibits excellent deodorizing performance of various malodorous gases such as hydrogen sulfide, ammonia, mercaptans, amines, and aldehydes that exist in the daily living environment. Not only that, but it is also highly safe because it is composed of non-toxic silicates, zinc compounds, and activated carbon.

Since the present adsorbent can be made into a fine powder, it can be easily supported on paper, sheets, etc., and has a thermal resistance of 500%.
It also has excellent processability, as it is stable up to temperatures around ℃ and can be kneaded into plastics.

[0038] Furthermore, it can be made into spherical particles, which are easy to handle and can be used in a wide range of applications.

Claims (4)

[Claims] 1. An inorganic adsorbent comprising particles consisting of a silicate, a zinc compound, and activated carbon, with activated carbon particles uniformly dispersed therein. 2. The inorganic adsorbent according to claim 1, wherein the deodorant particles are spherical. 3. The inorganic adsorbent according to claim 1, wherein the zinc compound and activated carbon are each contained in an amount of 1 to 4 parts by weight based on 5 parts by weight of the silicate. 4. Adjust the specific gravity of an aqueous solution containing a mixture of silicate and zinc compound to 1.5 to 2.5, add activated carbon particles, and mix. A method for producing an inorganic adsorbent consisting of a silicate, a zinc compound, and activated carbon, which comprises dropping the coagulating liquid dropwise into a coagulation bath consisting of two layers to produce spherical particles consisting of a silicate, a zinc compound, and activated carbon.