JP4314097B2 - Chemical substance adsorbent using bamboo charcoal - Google Patents

Description

  The present invention relates to an adsorbent capable of adsorbing an organic solvent or the like and purifying air or water.

  An adhesive used for building materials, such as wallpaper and floorboard, contains an organic solvent such as toluene, formaldehyde, or ammonia. Various chemical substances are also used in other building materials. Such chemicals continue to volatilize indoors for a long time after the building is completed, and eventually cause sick house syndrome, which adversely affects the human body.

  Sick house syndrome is a very big problem at present, and research on building materials that do not use chemical substances as much as possible, such as adhesives that reduce the amount of organic solvents and adhesives that do not contain ingredients harmful to the human body. Is underway. However, it is almost impossible to build a building that does not use such chemicals at all.

Therefore, research has been conducted on substances capable of adsorbing and decomposing such harmful substances.
Under such circumstances, activated carbon having a pore structure and high adsorptivity has been attracting attention in recent years, and a method of using a catalyst on activated carbon as an adsorbent for gas such as carbon monoxide has been reported. (See Patent Document 1).

JP 2002-126516 A

  As described above, activated carbon or the like carrying a catalyst is used as a gas adsorbent or the like. Further, activated carbon or charcoal that does not carry a catalyst is used for the purpose of deodorizing to remove various odors in the room. However, there are almost no reports on adsorbents having high adsorbability in acidic and basic organic solvents such as toluene, formaldehyde, and ammonia, which are said to cause sick house syndrome.

  The problem to be solved by the present invention is to provide a chemical substance adsorbing material using charcoal, which has a high adsorbing ability for both acidic and basic organic solvents without supporting a catalyst.

The adsorbent according to the present invention made to solve the above problems is bamboo charcoal fine powder 75 ~ that is pulverized so that the average particle diameter is 5 ~ 10μm after baking and carbonizing the bamboo at 650 ~ 900 ° C. 90% by weight, 5-15% by weight of a clay-like inorganic substance, and 5-10% by weight of a binder resin are mixed, and this is extruded into a honeycomb structure having a cell density of about 200 cells / inch ² An adsorbent capable of adsorbing both acidic and basic chemical substances, wherein the clay-like inorganic substance is sepiolite, kaolin, montmorillonite, chlorite, kaolinite, sericite, or a combination of two or more thereof. It is characterized by being.

  The present inventors considered that, among charcoal, bamboo charcoal having a particularly large specific surface area and pores having a wide distribution of several nanometers to several tens of micrometers can adsorb a large amount of substances having various molecular weights. .

  Conventionally, when producing charcoal, wood is fired at about 500 to 1000 ° C., and the pore structure of the charcoal changes depending on the calcining temperature, thereby changing the specific surface area.

  In the case of bamboo charcoal, when fired at a temperature of about 650 to 900 ° C., as shown in FIG. 1 (a), a pore structure in which pores of several nm are collected around pores having a diameter of several tens of μm, Inside the pores of several tens of μm, a tubular structure (hereinafter referred to as “nanotube structure”) having a diameter of the order of nanometers (FIG. 1B) is observed. There are a large number of very fine pores in the nanotube structure, and the presence of the nanotube structure is considered to improve the adsorption ability of a chemical substance having a particularly low molecular weight. However, when firing at 1000 ° C. or higher, as shown in FIG. 2, the nanotube structure is hardly seen.

  Moreover, the functional group of the pore surface of charcoal changes with the difference in calcination temperature. If the carbonization temperature is low, acidic functional groups will be present on the pore surface, and if the temperature is high, basic functional groups will be present. It is said that acidic substances are easily adsorbed when the carbonization temperature is high. For example, in the case of Bincho charcoal, calcination is performed at 1000 to 1100 ° C., and such charcoal tends to adsorb acidic substances.

  The present inventors have found that bamboo charcoal obtained by baking bamboo at 650 to 900 ° C. has a high adsorbing ability for both acidic and basic chemical substances. In order to further enhance the adsorption ability of the chemical substance possessed by this bamboo charcoal, the bamboo charcoal is pulverized and kneaded with a clay-like inorganic substance and a binder resin to form a honeycomb structure as shown in FIG. In order to efficiently adsorb chemical substances and the like.

  The honeycomb structure has 75 to 90% by weight of bamboo charcoal fine powder pulverized so as to have an average particle size of 5 to 10 μm, 5 to 15% by weight of clay-like inorganic material, and 5 to 10% by weight of binder resin, depending on circumstances. Is prepared by mixing an appropriate amount of water, and pressing or extruding the mixture. For the formation of this structure, the firing temperature of bamboo charcoal and the particle size of bamboo charcoal fine powder are important. When the firing temperature is 650 to 900 ° C., a uniform honeycomb structure can be formed. However, when a bamboo charcoal fine powder having a firing temperature of 1000 ° C. or higher is used, it becomes difficult to form a honeycomb structure. Also, when the average particle size is larger than 5 to 10 μm, it becomes difficult to form a honeycomb structure. In addition, the grinding | pulverization method of bamboo charcoal is not ask | required in particular, For example, it can carry out with a jet mill etc.

  As the clay-like inorganic substance, sepiolite, kaolin, montmorillonite, chlorite, kaolinite, sericite, or a combination of two or more thereof can be used. As the binder, it is possible to use celluloses such as methyl cellulose and carboxymethyl cellulose, polysaccharide resins such as dextrin, epoxy resins, furan resins, phenol furan resins, phenol resins, and the like. Select as appropriate. When the adsorbent is used for purification of water in particular, it is necessary to select a binder that does not elute into water and is harmless to the human body.

  The adsorbent according to the present invention has high adsorbability for both acidic and basic chemical substances, and causes chemical substances such as toluene, formaldehyde, and ammonia that cause chemical sensitivity such as sick house syndrome. Can be removed by adsorption.

After adding 150 g of water to a mixture of 800 g of bamboo bamboo charcoal fine powder pulverized to an average particle size of 7 μm, 100 g of clay-like inorganic substance (sepiolite), and 60 g of binder (methylcellulose), this is kneaded thoroughly. Was extruded to form a honeycomb structure. Thereafter, this was dried at 170 ° C. for 24 hours to obtain a honeycomb structure adsorbent having a cell density of about 200 cells / inch ² .

  Next, the adsorption ability of chemical substances (toluene, ammonia, formaldehyde, acetic acid) of this adsorbent was examined. Prepare nitrogen containing 50 ppm of toluene at the start of the experiment, nitrogen containing 60 ppm of ammonia at the start of the experiment, nitrogen containing 50 ppm of formaldehyde at the start of the experiment, and nitrogen containing 55 ppm of acetic acid at the start of the experiment. Changes in the amounts of these chemical substances in the presence were examined using a gas chromatograph, an ammonia detector or a formaldehyde detector.

The results are shown in FIGS. These figures show changes in the amount of chemical substances in the presence of no adsorbent (blank), Bincho charcoal obtained by firing at 1000 ° C, bamboo charcoal obtained by firing at 1000 ° C, and activated carbon. Is also shown.
As can be seen from FIGS. 4 to 7, when the adsorbent of the present invention is used, the amount of chemical substances in nitrogen is reduced to 1/5 or less within 1 hour and almost disappears after 24 hours. is doing. Thus, the adsorbent of the present invention has a high chemical substance adsorbing ability, and in particular, it can be seen from FIG. 5 that the adsorbing ability of ammonia is superior to other adsorbents.

  From the above, it was shown that the chemical substance adsorbing material according to the present invention has an excellent adsorption capacity that rapidly reduces both acidic and basic chemical substances when compared with the same amount of activated carbon and the like. .

In addition, although it showed about the change of the amount of chemical substances which exists in nitrogen in the above, the adsorbent which concerns on this invention shows the high adsorption capability similarly with respect to the chemical substance which exists in water. For this reason, the adsorbent according to the present invention can be used not only as an air cleaning material but also as a water cleaning material. Of course, it is possible to use it as a humidity control agent, a deodorizing agent, etc. like normal charcoal.
Furthermore, if the adsorbent is made in a cube shape as shown in FIG. 8, it can be easily used as an interior decoration or a building material. Although the size of the cube can be set arbitrarily, as an example, the length of each side of the cube is 3.5 cm, the length of each side of the honeycomb is 1 mm, and the thickness of the honeycomb partition walls is 0.3 mm. Examples of mm are listed.

  Moreover, since the chemical substance adsorbing material according to the present invention is easily regenerated by being exposed to sunlight for several hours, it can be used any number of times, and can be said to be an excellent material with a small environmental load.

(a) SEM photograph of the pore structure of bamboo charcoal fired at 800 ° C., (b) SEM photograph of an enlarged part of the nanotube structure of bamboo charcoal fired at 800 ° C. SEM photograph of the pore structure of bamboo charcoal fired at 1000 ° C. 1 is a schematic structural diagram of an adsorbent having a honeycomb structure according to the present invention. The graph which showed the time-dependent change of the amount of toluene contained in nitrogen at the time of using various adsorbents. The graph which showed the time-dependent change of the ammonia amount contained in nitrogen at the time of using various adsorbents. The graph which showed the time-dependent change of the amount of formaldehyde contained in nitrogen at the time of using various adsorbents. The graph which showed the time-dependent change of the amount of acetic acid contained in nitrogen at the time of using various adsorbents. The adsorbent according to the present invention having a cube shape.

Claims (2)

Bamboo charcoal powder baked at 650-900 ° C and carbonized and then ground to an average particle size of 5-10μm 75-90% by weight, clay-like inorganic substance 5-15% by weight, binder resin 5-10 wt% was mixed without supporting the catalyst, and this was extruded into a honeycomb structure having a cell density of ²⁰⁰ cell / inch ² (31 cell / cm ² ) , and toluene, ammonia, formaldehyde, and acetic acid were mixed. An adsorbent adsorbent, wherein the clay-like inorganic substance is sepiolite, kaolin, montmorillonite, chlorite, kaolinite, sericite, or a combination of two or more thereof. Adsorbent.   The adsorbent according to claim 1, wherein the binder resin is any one of cellulose, polysaccharide-based resin, epoxy resin, furan resin, phenol furan resin, phenol resin, or a combination of two or more thereof.

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