JPH10226508A - Glucomannan activated carbon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a glucomannan activated carbon to supplement the lack of the source material for activated carbon which largely depends on import, by drying a hydrated gel prepared from glucomannan as the main source material, carbonizing the obtd. dry solid and then activating. SOLUTION: Glucomannan, a coagulating agent such as calcium hydroxide, and if necessary, a carbon-contg. material which can be used as a carbon having high porous structure (such as plant-based, natural and synthetic materials) are mixed, to which 5 to 10 pts.wt. of water is added to 1 pt.wt. of the glucomannan. The mixture is stirred and kneaded to obtain a hydrated gel essentially comprising glucomannan. The amt. of water is preferably as small as possible in such a range that the glucomannan particles and the coagulating agent are uniformly and sufficiently in contact with each other in the hydrated gel. The hydrated gel is dried to obtain a dry solid. The dry solid is heated at 600 to 800 deg.C to carbonize and then heated at 850 to 1150 deg.C to activate in an atmosphere containing water vapor, air and combustion gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to activated carbon, and more particularly to activated carbon produced using glucomannan as a main raw material.

[0002]

BACKGROUND OF THE INVENTION Konjac potato, a plant of the taro family, contains the polysaccharide glucomannan (in a narrow sense) and other mannans in its corm, and these are collectively referred to as glucon mannan (in a broad sense). It is also called konjac mannan (konjac fine powder) because it is a commercially available konjac raw material.

[0003] Glucomannan to be used in the method for producing activated carbon of the present invention is not necessarily a pure product (glucomannan in a narrow sense), and konjac mannan (glucomannan in a broad sense) can of course be used. It is. Thus, in the following description, glucomannan in a narrow sense and a broad sense may be simply abbreviated as "mannan" unless otherwise specified, unless otherwise specified.

Now, the aqueous solution of mannan is Ca (OH)
_When it comes into contact with alkaline compounds (coagulants) such as _2, it gels, and when the resulting hydrated gel is heated, it becomes an irreversible elastic gel, a traditional Japanese food "konjac"
Is well known. More specifically, for example, after stirring mannan in water, konjac is left for about 60 to 120 minutes to completely dissolve the mannan particles (also referred to as swelling or particle opening), and then a coagulant is added. Then, the mixture is thoroughly kneaded to form a gel of mannan hydrate, then molded and heated to obtain an irreversible gel. The characteristics of mannan are:
In this way, konjac is used for foodstuffs.

However, in such a method for producing konjac, a sufficient amount of water must be used in preparing an aqueous solution of mannan in order to completely dissolve (completely swell) mannan and to knead it sufficiently after adding a coagulant. Must. That is, for 1 part by weight of mannan, the water used is 35-45.
Parts by weight are good working areas. For example, below 30 parts by weight, it is impossible to add an alkali agent and sufficiently knead after swelling due to the formation of a strong hydrated gel. It is not possible to add and homogenize. Thus, if the coagulant mannan contact is heterogeneous or insufficient,
Mannan's use of foodstuffs can result in sliminess and neto, as well as exacerbation of a strong aversion to non-edible products. Therefore, the use of foodstuffs by mannan has been hampered today even more than konjac.

[0006] Incidentally, as described above, mannan which can be produced by eliminating the complete dissolution seen during the production of konjac and the subsequent step of adding a coagulant and sufficiently kneading the hydrated mannan gel as described above, Rapidly soluble glucomannan composition according to the invention of the inventor (JP-A-5-3826)
3) can be mentioned as a preferable example.

[0007] In Japan, konjac potatoes are cultivated as upland agricultural products, and mannan obtained therefrom has conventionally been used only as a raw material for konjac, and its excellent properties have not been effectively utilized. The main reason is that the use of about 40 parts by weight of water with respect to 1 part by weight of mannan is a standard process for the production of konjac, and the konjac of the product is strongly alkaline (pH 11.0-13.
0) Mannan, the raw material, is present in an aqueous solution and has a high elasticity, such as requiring special labor for edible use. Has been reached.

The inventor of the present invention, as seen in the aforementioned “quickly dissolving glucomannan composition”, mixes powdered auxiliary materials (starch, coagulant, etc.) with fine powder of mannan, and hydrates and mixes these. Sometimes, the coagulant easily and homogeneously and sufficiently contacts the mannan particles in the mannan hydrate to reach an equilibrium state. For example, 1 part by weight of the mannan powder raw material and, if necessary, 5-10 parts of water. The fact that mannan can be homogeneously coagulated even in a small amount of parts by weight means that the hydration dissolution and hydrate viscosity, which are the characteristics of mannan, and the irreversible coagulation can be used in a wide range of applications. From, for example, from research to be used for multipurpose such as thickening, emulsifying, adhesive, sticky, coating,
Food film, frozen food, animal meat food, confectionery, and other food supplements, paints, fertilizers, pesticides, industrial adjustment and improvement of soil, etc., as well as capsule shells for medical X-ray fluoroscopy Despite extensive research into the development of applications for drug binders and the like, further application development of mannan is desired.

[0009]

SUMMARY OF THE INVENTION Under the background of the prior art described in the preceding paragraph, an object of the present invention is to develop and provide further uses of glucomannan.

[0010]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, glucomannan
In addition to the above-mentioned uses, the present inventors have found that they can be a good raw material for activated carbon, and have completed the present invention based on such findings.

[0011] That is, the present invention is characterized in that it can be produced by drying a hydrated gel containing glucomannan as a main raw material, carbonizing the resulting dried solid, and then activating. Regarding activated carbon.

The activated carbon of the present invention is referred to as glucomannan activated carbon because its main raw material is glucomannan.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

Regarding the method for producing activated carbon, "a zinc chloride solution is added to wood flour and impregnated, and then 600-70 under anoxic condition.
Heat to 0 ° C and carbonize. Alternatively, heating is performed at 800 to 1,200 ° C. while blowing steam into charcoal or coal. "
(Japanese Society of Food Industry, “New Edition of the Food Industry General Encyclopedia” P.2
58, published by Korin Co., Ltd. in 1993), and "After sufficiently carbonizing charcoal, coconut palm, coal char, and other raw materials, high-temperature treatment with steam or impregnation with an aqueous solution such as zinc chloride and high-temperature sintering, etc. It is activated by a method and is manufactured. "(" Chemistry Dictionary "P. 275, published by Tokyo Chemical Industry Co., Ltd., 1994).

Activated carbon is classified into powdered activated carbon, granular activated carbon, fibrous activated carbon, and the like according to the shape of the activated carbon according to the purpose of use. Further, granular activated carbon can be classified into crushed carbon and spherical or cylindrical shaped carbon. it can. The activated carbon of the present invention can be easily made into granular activated carbon, especially crushed carbon.

In Japan, the activation treatment for producing granular activated carbon employs both gas activation and chemical activation.
Activated carbon produced through such activation treatment is used while making the most of each characteristic. However, in the case of granular activated carbon, the development of new products and new technologies is still an issue in fierce international competition. In other words, we need to ensure stable supply of high-quality raw materials, search for alternative raw materials, develop new products using those raw materials (establish demand that meets the purpose of use), and provide products that are stable for reprocessing and other issues. It can be mentioned as.

Activated carbon is a porous carbon material having an adsorbing function. The raw material is, for example, a carbon material obtained by calcining (carbonizing) the material and reacting with an activating gas such as steam at a high temperature to form a porous carbon material. The present inventor has continued his research, since it is a carbon-containing substance that becomes a porous carbon material when it is mixed with an activator such as zinc chloride and then calcined (carbonized, activated). Was.

As a raw material of activated carbon, wood-based,
Plant raw materials including fruit husks, fruit seeds, and others; natural materials including seaweeds and others; synthetic materials including regenerated fibers and others; and, in the case of powdered activated carbon, plant raw materials such as sawdust, peat charcoal, In addition to mineral raw materials such as lignite, special raw materials such as pulp waste liquor are also included. On the other hand, granular activated carbon includes charcoal, coconut shell, low-ash peat coal, lignite, lime blue coal, and anthracite. Most of the raw materials for general-purpose activated carbon depend on imports from overseas, and it is necessary to ensure qualitative and quantitative stability.

Next, the production of activated carbon by a conventional method will be described with reference to examples.

One example is the use of a carbonizer to dry distill and carbonize sawdust (the air is cut off to strongly heat the sawdust solids and recover volatiles and oily substances produced by thermal decomposition), and then to remove the carbides. The activation reaction is promoted by bringing the mixture into contact with a gas in which steam, air, a combustion gas or the like is appropriately mixed in an activation furnace at a temperature of 850 to 1150 ° C. In this case, the obtained carbide of the intermediate raw material is gradually heated to 600 to 800 ° C. so as not to cause the deformation, cracking, fusion, etc. of the particles in the carbonization treatment.
Heat until As for the carbonization treatment, it is desirable that the carbonization operation of the raw material can be easily controlled and that a homogeneous carbide can be continuously produced, and the activation treatment can also be performed according to the application, as in the case of coconut shell activated carbon. It is recommended that the type and size of the activation furnace be selected depending on the type and properties of the desired activated carbon and the activation reaction rate.

The production of granulated activated carbon will be described as another example. For the raw material, for example, the most suitable raw material is selected from charcoal, coconut shell charcoal, coal, coke, and the like. In addition, a catalyst effective for the activation reaction, an acid and a base are appropriately added. The binder is used in an amount of 0.4 to 0.
The mixture was uniformly kneaded while being heated, formed into a uniform particle size, dried, and dried in a combustion gas stream.
It is heated to about 50 ° C. to harden the surface and then carbonized, or the dried product is gradually heated to 600 to 800 ° C. and carbonized to form a dense hard carbide. The activation treatment promotes the activation reaction of the carbide with steam and carbon dioxide at a temperature of 750 to 1050 ° C. Further, the commercialization of the activated carbon involves washing the inorganic matter (ash) in the carbon with dilute hydrochloric acid or the like, deashing it, and further washing with water. After repeated purification, dry and complete.

The activated carbon of the present invention can be produced by appropriately relying on such a conventional method for producing activated carbon, except that glucomannan is used as a raw material. That is, mannan is a good raw material in any of the methods for producing activated carbon.

More specifically, the activated carbon of the present invention can be produced by drying a hydrated gel containing glucomannan as a main raw material, carbonizing the obtained dried solid, and then activating. It can be produced, for example, by molding and drying a hydrated gel (glue) containing glucomannan as a main raw material, subjecting the obtained dried solid to a carbonization treatment, and then performing an activation treatment. .

Here, the hydrated gel (glue) containing glucomannan as a main material is used from the viewpoint of, for example, glucomannan and a coagulant such as calcium hydroxide and, if necessary, carbon having a developed pore structure. It can be prepared by mixing powders of raw materials such as carbon-containing substances (vegetables, natural materials, synthetic materials, etc.), adding water thereto, and stirring and kneading. From the viewpoint of forming and drying the hydrated gel, the amount of water used is preferably as small as possible as long as the glucomannan particles and the coagulant can be uniformly and sufficiently contacted in the hydrated gel. Can be achieved by mixing powder of glucomannan and a coagulant, adding water thereto, and stirring. Specifically, the amount of water used is, for example, 5 to 5 parts by weight of glucomannan.
It can be 10 parts by weight.

The hydrated gel thus obtained is appropriately shaped so as to be easily dried, and then dried. Then, the obtained dried solid is subjected to a carbonizing treatment and an activation treatment sequentially.
As described above, the carbonization treatment and the activation treatment can be appropriately performed by a conventional method. Further, after the activation treatment, a purification treatment is performed as necessary. The purification treatment can also be appropriately performed by a conventional method.

The activated carbon of the present invention is, of course, not limited to the activated carbon produced by the method described above, but is activated carbon produced from a hydrated gel containing glucomannan as a main raw material. These are all included in the glucomannan activated carbon of the present invention as long as they have the same activated carbon properties as those obtained by the various methods.

[0027]

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

Example 1 40 g of mannan (konjac fine powder), 19.8 g of "Avicel" (crystalline cellulose powder manufactured by Asahi Kasei Corporation) and C
a (OH) ₂ 1.2 g (total 60 g) was powder mixed, and the mixture was poured into 480 g of water (20 ° C.) and stirred with a hand mixer. After about 5 minutes when the viscosity increased, the stirring was stopped. Press and extend with a resin spatula for about 1 minute and knead to obtain 540 g of mannan hydrated gel (glue), put it in a vat and spread it, leave it for about 2 hours to stabilize, (4cm × 15cm × 3.3c
m), after drying by heating in a dryer at 60 ° C for 2 hours,
Dry for another 72 hours in a thermostat set at
A dry solid like (6) wood chips was obtained. Next, the solid is heated in a baking oven for about 30 minutes to raise the temperature to 450 ° C., and carbonized by dry distillation.
After activation (activation) by contacting with an appropriate mixed gas of steam and carbon dioxide at 000 ° C., cooling, then washing with dilute hydrochloric acid and decalcification, washing with water and drying, 6 activated carbons (120 g) Was obtained. The activated carbonized carbonized raw material as a raw material of activated carbon, which is a hard coagulate of mannan, progressed to an activated carbon.

To test the adsorption performance (liquid phase) of this product, 20 g of the crushed product
Soaked in 0ml for about 30 minutes (twice every 10 minutes)
As a result, it was confirmed that the color was decolorized to the same degree of coloring as the 0.03% aqueous caramel solution (85% decolorization).

[0030]

The use of activated carbon has been dramatically expanded today, and the demand for the activated carbon has increased remarkably. Activated carbon has an ever-increasing variety of shapes and functions, and its use is complicated, and it is becoming more sophisticated.However, the use of activated carbon will be further developed in the future, and it will play an important role as an essential element in social organizations However, since its raw materials mostly depend on imports from foreign countries, raw materials prices, quality and quantity are extremely unstable, and they are in short supply. Under the present circumstances, glucomannan, which is a raw material of the activated carbon of the present invention, has a long and safe track record of being used as a food product in Japan as an agricultural product, and even under the present circumstances, several times the planned production is possible (Japan Konjac Association, 1995, annual field cultivation results survey report).

According to the present invention, the above-mentioned shortage of activated carbon raw material is compensated for by utilizing glucomannan, and new demand for glucomannan as a raw material for activated carbon is realized, contributing to the promotion of agricultural production. In addition, the economic effect of the activated carbon according to the present invention is extremely large.

Claims (1)

[Claims] 1. A glucomannan activated carbon characterized in that it can be produced by drying a hydrated gel containing glucomannan as a main raw material, carbonizing the resulting dried solid, and then activating it.