JPH01288336A - Adsorbent for aldehydes - Google Patents

Abstract

PURPOSE:To exhibit an excellent adsorption property for aldehydes in a gas phase by using an activated charcoal impregnated with toluidine and/or phenylenediamine in a specified proportion as an adsorbent. CONSTITUTION:An activated charcoal is impregnated with 1-50wt% (of the activated charcoal) o-, m- or p-toluidine and/or o-, m- or p-phenylenediamine as an adsorbent for aldehydes. The impregnated charcoal thus obtained is very excellent in adsorption property for aldehydes and this impregnated charcoal itself is almost odorless. Furthermore, it has such a good performance even for a low concentration aldehyde that it is usable for a household air-cleaning agent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an adsorbent having excellent adsorption performance for aldehydes in a gas phase.

[Prior art and problems to be solved by the invention] Lower aliphatic aldehydes such as formaldehyde and acetaldehyde are typical malodorous gases in daily life. For example, formaldehyde is generated from furniture such as cupboards and wardrobes, and new construction materials using synthetic resin sheets.

In addition, acetaldehyde is extremely abundant in cigarette smoke in daily life, and is also generated during drying of chicken manure, manufacturing of printing ink, and manufacturing of coke.

Conventionally, wet and dry methods are known for deodorizing these lower aliphatic aldehydes. The wet method is a method in which gas is cleaned with water or a chemical solution, but this method inevitably causes the water or chemical solution to scatter, making it difficult to use indoors and posing problems in the treatment of wastewater. In addition, the dry method uses activated carbon to remove adsorption, but conventional activated carbon has a low aldehyde storage rate, and the aldehyde concentration in a home environment is much lower than in a factory where aldehydes are used. Adsorption efficiency is not necessarily good in terms of total aldehyde amount. In addition, special activated carbon impregnated with ammonium salt, sulfite, or acid sulfite (Japanese Unexamined Patent Publication No. 53-29292), and one impregnated with aniline (Japanese Unexamined Patent Publication No. 60-54095) have been devised.
The effect is not completely satisfactory.

[Means to solve the problem]

Therefore, the present inventors conducted various studies in search of an even stronger adsorbent, and found that an adsorbent obtained by impregnating toluidine and/or phenylenediamine on activated carbon can absorb aldehydes such as formaldehyde and acetaldehyde in the gas phase. The present invention has been achieved based on the discovery that this is an extremely effective adsorbent for these species.

That is, the present invention provides activated carbon with one or more selected from the group consisting of ortho-, meta-, and para-toluidine and ortho-, meta-, and para-phenylenediamine.
The present invention provides an adsorbent for aldehydes, characterized in that it is impregnated with 50% by weight (based on activated carbon).

Toluidine and phenylenediamine exhibit similar properties to aniline toward aldehyde groups, so their adsorption performance for aldehydes is not inferior to aniline. Moreover, activated carbon generally has a property that the larger the molecule, the easier it is to adsorb.
When impregnating a reagent with activated carbon, toluidine and phenylenediamine are more easily adsorbed than aniline.

When toluidine or phenylenediamine is impregnated according to the present invention, the adsorption effect is superior to that of conventional aniline impregnation.

The reason for this is that toluidine has a larger molecular weight than aniline and is easily adsorbed on activated carbon, and the methyl group, which is an electron donating group, is bonded to the aromatic ring, which increases the electron density of the amine group nitrogen. It is thought that this increases the probability of condensation with the aldehyde group of the malodorous gas (formation of a Schiff base). Similarly, phenylenediamine has a larger molecular weight than aniline and is easily adsorbed on activated carbon. In addition, while aniline has one functional group in one molecule that can condense with the aldehyde group of malodorous gas to form a Schiff base, phenylenediamine has two functional groups in one molecule. It is believed that diamine-impregnated carbon exhibits superior effects than aniline-impregnated carbon.

Furthermore, toluidine and phenylenediamine have much lower odor than aniline, whether ortho-, meta-, or para-. Among them, para-toluidine and ortho-, meta-, and para-phenylenediamine are solid at room temperature and have almost no odor, making them easy to handle and having a wide range of applications, making them the most suitable for impregnating activated carbon.

The amount of reagent impregnated for activated carbon impregnated with toluidine or phenylenediamine to exhibit sufficient performance as an adsorbent depends on the type of impregnated reagent, but the amount of reagent impregnated is 1.
The content is preferably in the range of 50% by weight (based on activated carbon). If it is less than 1% by weight, the duration of the adsorbent's effect will be shortened, which is undesirable.On the other hand, if it exceeds 50% by weight, the reagent will have a slight odor, and liquids such as meta-toluidine and ortho-toluidine may be used. In the case of reagent-impregnated charcoal, it becomes a little sticky, making it impractical as an adsorbent.

The activated carbon used to obtain the adsorbent of the present invention is not particularly limited, and commercially available coconut shell activated carbon, coal-based activated carbon, bone charcoal, etc. of various particle sizes can be used. The particle size of the activated carbon is appropriately selected depending on the purpose of the adsorbent, how it is used, etc.

Examples of the method for impregnating activated carbon with the above-mentioned reagent include a method in which the above-mentioned activated carbon is immersed in a reagent solution to allow the activated carbon to adsorb the reagent, followed by filtering and drying. In this case, the solvent for dissolving the reagent is preferably a polar solvent, such as water, methanol, or a mixed solvent of both solvents. If a non-polar solvent is used, the solvent will be more easily adsorbed onto the activated carbon, which may hinder the adsorption of the reagent onto the activated carbon. Other methods include (i) a gas phase adsorption method in which a carrier gas containing a reagent is brought into contact with activated carbon;
ii) a sprinkle method in which the reagent is directly sprinkled onto the activated carbon, (ii)
i) Equilibrium adsorption method, in which a reagent and activated carbon are placed in a sealed container and heated at high temperature to cause adsorption, can be mentioned.

The adsorbent of the present invention can be used in any method that allows contact with gas. For example, in a method of adsorbing gas by aerating gas into a fixed bed, moving bed or fluidized bed,
Alternatively, the adsorbent of the present invention can be used in a method of adsorbing gas by contacting it with a gas by a stationary method.

As described above, the adsorbent of the present invention is extremely excellent as an adsorbent for aldehydes in the gas phase.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is of course not limited thereto.

Example 1 Commercially available coconut shell activated carbon (particle size 42-80 mesh) was
It was dried at 0°C for 3 hours and immersed in a 10% by weight bara-toluidine methanol solution for 2 hours. Thereafter, the activated carbon was collected by filtration and air-dried to remove excess methanol adsorbed on the activated carbon. The baratoluidine-added charcoal thus obtained had 16.0% by weight of baratoluidine impregnated therein.

Bara-toluidine-impregnated carbon 10 obtained by the above method was placed in a 6.5 β desiccator with an acetaldehyde concentration of 50 ppm.
0 mg was added, and the acetaldehyde concentration in the desiccator was measured over time by gas chromatography with FID. As a control, 100 mg of activated carbon not impregnated with para-toluidine was operated in the same manner. (Concentration of acetaldehyde in the desiccator after 30 minutes)/(initial concentration of acetaldehyde) was determined to be 0.07 for the para-toluidine-impregnated charcoal and 0.55 for the control unimpregnated charcoal.

Example 2 The same procedure as in Example 1 was repeated except that a 10% by weight methanol solution of meta-phenylenediamine was used instead of the 10% by weight para-toluidine methanol solution in Example 1. As a result, impregnated carbon with 13.8% by weight of meta-phenylenediamine impregnated was obtained.

As a result of gas chromatography analysis in the same manner as in Example 1, meta-phenylenediamine-impregnated carbon 3
Acetaldehyde concentration in the desiccator after 0 minutes)/(
The initial concentration of acetaldehyde) was 0.12.

〔Effect of the invention〕

As shown in the above examples, the impregnated carbon of the present invention has extremely excellent aldehyde adsorption performance. Moreover, these impregnated carbons themselves are almost odorless. Furthermore, it has good adsorption and deodorizing performance even at low aldehyde concentrations, and can be used as a general household air cleaner.

Claims (1)

[Claims] Activated carbon is impregnated with 1 to 50% by weight (based on activated carbon) of one or more selected from the group consisting of ortho-, meta-, para-toluidine and ortho-, meta-, para-phenylenediamine. Characteristic adsorbent for aldehydes.