JP5863532B2 - Activated carbon and manufacturing method thereof - Google Patents

Description

  The present invention relates to activated carbon suitable for treating a liquid phase, particularly an aqueous phase.

  Activated carbon is used as an adsorbent in the treatment of water or aqueous solutions to remove impurities and adjust the concentration of dissolved components.

  As raw materials for the activated carbon, plant raw materials such as wood powder and coconut shell, coal-based raw materials such as lignite, lignite, bituminous coal, anthracite, and synthetic raw materials such as phenol resin and vinylidene chloride resin have long been known. (Non-patent Document 1).

  For example, it is known that plant-based raw materials such as coconut husks are useful raw materials that have a stable quality, are low in impurities, can be obtained in large quantities, and can have high hardness. In addition, activated carbon obtained from plant-based raw materials such as coconut shell is rich in micropores with a diameter of 2 nm or less, and can be suitably used for gas phase adsorption or removal of volatile organic compounds in water such as water purifiers. It is said that decolorization performance is not so high.

  On the other hand, activated carbon with various performances can be obtained from coal-based raw materials, but it is difficult to obtain activated carbon with uniform performance due to the large distribution of properties in the ore.

  Therefore, in order to obtain activated carbon with high decolorization performance and uniform performance, a method of obtaining granular activated carbon by a zinc chloride activation method or a phosphoric acid activation method has been industrialized. However, the activated carbon has insufficient hardness, remains zinc and phosphoric acid due to activation chemicals, and has a high environmental load in the manufacturing process, and it is necessary to take pollution measures in manufacturing. It was not satisfactory enough.

  That is, the activated carbon used as an adsorbent has been studied for its decolorization performance, but it is not only high in decolorization effect, but also the desired component required in purification operations using activated carbon in industries such as food and pharmaceuticals. No development has been made from the viewpoint of low adsorption of (low molecular weight components). In addition, the fact is that such an easy method for producing activated carbon has not been realized.

New activated carbon-basics and applications, Kodansha, 1992, p.55

  An object of the present invention is to provide an activated carbon that is easy to prepare and has excellent decolorizing performance, and a method for producing the same. Also, an adsorbent containing activated carbon having excellent decolorization performance, and capable of suppressing loss of necessary components as much as possible while exhibiting excellent decolorization performance when processing a solution containing various components Is to provide.

  In view of the above problems, the present inventors have conducted research to obtain activated carbon having high decolorization performance and reduced adsorption amount of low-molecular substances, and as a result, activated carbon having a specific mesopore volume value is the subject. Found to solve. It has also been found that the activated carbon can be produced by subjecting a carbonaceous raw material to carbonization treatment and activation treatment under specific conditions.

That is, this invention relates to the following activated carbon and its manufacturing method.
Item 1. Activated carbon having a mesopore volume per unit volume of 0.06 ml / ml or more and a mesopore volume ratio of 0.3 or more in the pore volume up to a diameter of 30 nm.
Item 2. The activated carbon according to claim 1, which is granular.
Item 3. Item 3. The activated carbon according to Item 1 or 2, wherein the hardness measured by JIS K1474 is 70% by mass or more.
Item 4. Item 4. An adsorbent for liquid phase treatment comprising the activated carbon according to any one of Items 1 to 3.
Item 5. Item 5. A method for treating water or an aqueous solution using the liquid phase treatment adsorbent according to Item 4.
Item 6. Item 2. The method for producing activated carbon according to Item 1, wherein the activated carbon raw material is carbonized at 500 ° C. or lower and then steam activated.
Item 7. Item 7. The production method according to Item 6, wherein a coconut shell material is used as the activated carbon material.

The activated carbon of the present invention has excellent decolorization performance.
The adsorbent for liquid phase treatment containing the activated carbon of the present invention is excellent in decolorization performance and can suppress the adsorption of the required low molecular weight active ingredient as much as possible. it can.
Therefore, it can be used for a wide range of chemical and food production applications.
The adsorbent of the present invention is easy to prepare.

  Hereinafter, the present invention will be described in detail.

Activated carbon The activated carbon of the present invention is activated carbon having a mesopore volume per unit volume of 0.06 ml / ml or more and a proportion of the mesopore volume in the pore volume up to 30 nm in diameter being 0.3 or more. Here, the mesopore volume means a pore volume of 2 to 30 nm in diameter measured by the nitrogen adsorption method and calculated by the Cranston-Inclay method, and is a pore involved in the adsorption performance of the colored substance. On the other hand, pores having a diameter of 2 nm are called micropores, and are pores having a size that is involved in adsorption of gas phase molecules, volatile organic compounds, and molecules having a molecular weight of 100 or less.

  The mesopore volume per unit volume is a product of the mesopore volume determined by the above method and the packing density.

  In the activated carbon of the present invention, the mesopore volume per unit volume may be 0.06 ml / ml or more, preferably 0.08 ml / ml or more, more preferably 0.1 ml / ml or more. When the mesopore volume has the above numerical value, the decolorization performance is remarkably improved, so the upper limit is not limited, but, for example, a range of about 0.08 to 0.2 ml / ml is more from a practical viewpoint. preferable.

  The ratio of the mesopore volume to the pore volume up to 30 nm in diameter is the mesopore volume determined by the above method up to the diameter of 30 nm calculated from the nitrogen adsorption amount at the relative pressure of 0.931 at the liquid nitrogen boiling temperature. Divided by the pore volume.

  In the activated carbon of the present invention, the proportion of the mesopore volume in the pore volume up to 30 nm in diameter may be 0.3 or more, preferably 0.4 or more, more preferably 0.5 or more. The upper limit value of the mesopore volume ratio is not limited, and can be set as appropriate depending on the type of the target adsorbent. Preferably, it is 0.3-1.0.

  By satisfying a specific value related to the mesopore volume, the above-mentioned problem of the present invention can be solved.

  The hardness of the activated carbon of the present invention measured by JIS K1474 is preferably 70% by mass or more. Preferably it is 80 mass% or more. When the hardness is 70% by mass or more, it is preferable from the viewpoint of generating less fine powder when used as granular coal.

The loss on drying, the packing density, and the specific surface area of the activated carbon are not particularly limited. Usually, the loss on drying is 5.0 mass% or less, the packing density is 0.15 to 0.6 g / mL, and the specific surface area is in the range of 700 to 2500 m ² / g.

  The activated carbon of the present invention may take any form such as powdered activated carbon, granular activated carbon (such as crushed, spherical, cylindrical shaped charcoal), fibrous activated carbon, activated carbon formed into a honeycomb shape, etc. From the viewpoint of adsorption performance and handling, granular activated carbon is preferred. Moreover, you may shape | mold in the column shape or spherical shape.

Production Method The activated carbon of the present invention is produced by carbonizing at 500 ° C. or lower and then performing a steam activation treatment.

  As a raw material for producing the activated carbon of the present invention, generally used raw materials for activated carbon can be widely used. For example, coconut shell (specific examples: palm coconut shell, coconut coconut shell, etc.), coal, coke, wood flour, sawdust, natural fiber (specific example: hemp, cotton, etc.), synthetic fiber (specific example: rayon, polyester, etc.), Synthetic resins (specific examples: polyacrylonitrile, phenol resin, polyvinylidene chloride, polycarbonate, polyvinyl alcohol, etc.) and the like. Among these, a raw material from which granular activated carbon suitable for use in a packed state can be obtained is preferable. From such a viewpoint, a coconut shell is preferable, and a palm coconut shell is particularly preferable.

( Carbonization treatment )
The temperature in the carbonization treatment is preferably 500 ° C. or less, and more preferably about 200 ° C. to 400 ° C. Normally, in the production of activated carbon, from the viewpoint of maximizing the gas adsorption rate of carbides, carbonization is performed at 600 ° C to 800 ° C, but in the present invention, carbonization is performed at 500 ° C or lower, which is lower than conventional. Thus, activated carbon having mesopores developed after the activation reaction can be obtained.

  The carbonization time can be appropriately set depending on the raw materials used and the equipment for carbonization, but is about 0.5 to 10 hours, preferably 0.5 to 5 hours, more preferably about 0.5 to 2 hours.

  The carbonization is performed using a known production facility such as a rotary kiln.

  The volatile content of the carbonized product is 5 to 40% by mass, preferably 10 to 40% by mass, and more preferably 20 to 40% by mass.

( Activation processing )
The activation method is not particularly limited. For example, the activation method described in “Activated carbon industry” heavy chemical industry communication company publication (1974) p.23-37, for example, the activation method by active gases, such as water vapor, oxygen, and carbon dioxide, phosphoric acid, zinc chloride, etc. The activation method with the used chemicals is appropriately used. Among these, steam activation is preferable from the viewpoint of obtaining activated carbon having a hardness suitable for use.

  The activation process is performed in a temperature range of about 750 to 1050 ° C. using known production equipment such as a rotary kiln and a fluidized furnace.

  The activation time varies depending on the raw material used, the activation temperature, the production equipment, etc., and cannot be generally stated, but is preferably about 0.5 to 24 hours. 1 to 24 hours is particularly preferable.

  Thereafter, the activated carbon that has been subjected to the activation treatment is sieved to obtain a uniform particle size.

  The particle size of the activated carbon of the present invention measured by JIS K1474 is not particularly limited, but usually 0.075 to 5 mm, preferably 0.1 to 4 mm, more preferably 0.15 to 3 mm.

  The obtained activated carbon may be washed with a mineral acid such as hydrochloric acid, nitric acid, sulfuric acid or phosphoric acid by a known method. For example, cleaning can be performed by bringing activated carbon into contact with hydrochloric acid. The contact can be carried out by immersing activated carbon in hydrochloric acid having an appropriate concentration and amount, or circulating hydrochloric acid through activated carbon. Thereby, the desired amount of chloride ions can be adsorbed on the activated carbon.

  The concentration of hydrochloric acid may be any concentration that can neutralize the alkali content contained in the activated carbon and dissolve the metal salt contained as an impurity. For example, 0.1-15 mass fraction% as hydrogen chloride, preferably 0.1-5 The mass fraction% is mentioned.

  Activated carbon used for washing may be in an activated state or may be washed with water in advance to remove water-soluble inorganic components.

  After washing with the mineral acid, it may be further washed with water. Further, it may be used as an impregnated activated carbon impregnated with chemicals for various purposes.

Adsorbent for liquid phase treatment The activated carbon of the present invention can be used as an adsorbent for liquid phase treatment.

  The adsorbent for liquid phase treatment in the present invention means an adsorbent used for processing a liquid phase containing water.

  The liquid phase to be treated by the adsorbent for liquid phase treatment of the present invention includes drinking water; groundwater; wastewater; industrial water; aqueous solutions such as intermediates and reaction products produced in chemical factories; For example, unfinished products are exemplified.

  There are no particular limitations on the adsorption target of the adsorbent for liquid phase treatment of the present invention. For example, odorous substances such as diosmin and 2-methylisoborneol contained in the water to be treated, organochlorine compounds such as dichloromethane and chloroform, and alkylbenzene Examples include surfactants such as sodium sulfonate, chromaticity components, humic substances, organic compounds such as waste mineral oil, intermediates such as sodium glutamate, aqueous sugar solution, and iodine, reaction products, and valuables.

  The adsorbent for liquid phase treatment of the present invention can be preferably used as an adsorbent used for removing impurities in the liquid phase, adjusting the concentration of the active ingredient, and collecting the active ingredient. It is particularly suitable for applications that require decolorization while maintaining the desired product and component concentrations. Therefore, it can be suitably used for purification of various aqueous solutions, separation of components, concentration adjustment, etc. in chemical / food factories.

  Hereinafter, the present invention will be specifically described with reference to examples and test examples, but the present invention is not limited thereto.

[Example 1]
Carbonated products were prepared by passing palm coconut shells from Sumatra, Indonesia, through a rotary kiln maintained at 400 ° C. over 1 hour. The volatile content of this carbonized product according to JIS M8812 was 31% by mass. This carbonized product was passed through a sieve and a crusher, and the particle size was adjusted to 2.36 to 0.500 mm (8/32 mesh). 200 g of this carbonized product was put into an external heating electric furnace having an internal volume of 6 L maintained at 900 ° C., taken out after various times shown in Table 1, cooled to room temperature in an inert atmosphere, and adsorbent No. 1 to Got 4.

[Example 2]
Carbonated products were prepared by passing palm coconut shells from Sumatra, Indonesia, through a rotary kiln maintained at 400 ° C. over 2 hours. The volatile content of this carbonized product according to JIS M8812 was 27 mass%. This carbonized product was passed through a sieve and a crusher, and the particle size was adjusted to 2.36 to 0.500 mm (8/32 mesh). 200 g of this carbonized product is put into an external heating electric furnace having an internal volume of 6 L maintained at 900 ° C., taken out after various times shown in Table 1, cooled to room temperature in an inert atmosphere, and adsorbent No. 5 to 8 got.

[Example 3]
Carbonated products were prepared by passing palm coconut shells from Sumatra, Indonesia, through a rotary kiln maintained at 500 ° C. over 2 hours. The volatile content of this carbonized product according to JIS M8812 was 4.4 mass%. This carbonized product was passed through a sieve and a crusher, and the particle size was adjusted to 2.36 to 0.500 mm (8/32 mesh). 200 g of this carbonized product is put into an external heating electric furnace having an internal volume of 6 L maintained at 900 ° C., taken out after various times shown in Table 1, cooled to room temperature in an inert atmosphere, and adsorbent No. 9 to 11 was obtained.

[Example 4]
Carbonated products were prepared by passing palm coconut shells from Sumatra, Indonesia, through a rotary kiln maintained at 400 ° C. over 30 minutes. The volatile content of this carbonized product according to JIS M8812 was 37.1% by mass. This carbonized product was passed through a sieve and a crusher, and the particle size was adjusted to 2.36 to 0.500 mm (8/32 mesh). 200 g of this carbonized product is put into an external heating type electric furnace having an internal volume of 6 L maintained at 900 ° C., taken out after various times shown in Table 1, cooled to room temperature in an inert atmosphere, and adsorbent No. 12 to I got 15.

[Example 5]
Carbonized products were prepared by passing coconut coconut shells from Mindanao, Philippines, through a rotary kiln maintained at 400 ° C. over 2 hours. The volatile content of this carbonized product according to JIS M8812 was 24% by mass. This carbonized product was passed through a sieve and a crusher, and the particle size was adjusted to 2.36 to 0.500 mm (8/32 mesh). Adsorbent No. 16 was obtained by placing 200 g of this carbonized product in an external heating electric furnace having an internal volume of 6 L maintained at 900 ° C., taking it out after 3 hours, and cooling it to room temperature in an inert atmosphere.

[Comparative Example 1]
Carbonized products were prepared by passing coconut coconut shells from Mindanao, Philippines, through a rotary kiln maintained at 400 ° C. over 2 hours. The volatile content of this carbonized product according to JIS M8812 was 24% by mass. This carbonized product was passed through a sieve and a crusher, and the particle size was adjusted to 2.36 to 0.500 mm (8/32 mesh). 200 g of this carbonized product was put into an external heating electric furnace having an internal volume of 6 L maintained at 900 ° C., taken out after various times shown in Table 1, cooled to room temperature in an inert atmosphere, adsorbent No. 17 and 18 was obtained.

[Comparative Example 2]
Carbonized products were prepared by passing coconut coconut shells from Mindanao Island, Philippines, through a rotary kiln maintained at 500 ° C. over 2 hours. The volatile content of this carbonized product according to JIS M8812 was 5% by mass. This carbonized product was passed through a sieve and a crusher, and the particle size was adjusted to 2.36 to 0.500 mm (8/32 mesh). 200 g of this carbonized product was placed in an external heating electric furnace having an internal volume of 6 L maintained at 900 ° C., taken out after various times shown in Table 1, cooled to room temperature in an inert atmosphere, and adsorbent No. 19 and 20 was obtained.

[Comparative Example 3]
A coconut coconut shell from Mindanao, Philippines was passed through a rotary kiln maintained at 400 ° C. for 1 hour to prepare a carbonized product. The volatile content of this carbonized product according to JIS M8812 was 25% by mass. This carbonized product was passed through a sieve and a crusher, and the particle size was adjusted to 2.36 to 0.500 mm (8/32 mesh). 200 g of this carbonized product was put into an external heating electric furnace having an internal volume of 6 L maintained at 900 ° C., taken out after various times shown in Table 1, cooled to room temperature in an inert atmosphere, and adsorbent No. 21- Got 23.

About the obtained activated carbon of an Example and a comparative example, performance was analyzed according to the following measuring method, and the result was shown in Table 1-Table 3.
<Measurement of pore volume>
The pore distribution was calculated from the nitrogen adsorption isotherm at the boiling point of liquid nitrogen by the Cranston-Inclay method.
<Measurement of packing density>
It was measured by the method described in JIS K1474.
<Measurement of mesopore volume>
The mesopore volume per unit volume is obtained by calculating the pore volume in the range of 2-30 nm in diameter from the nitrogen adsorption isotherm by the Cranston-Inclay method and calculating the product with the packing density obtained by the above method. It was.
Further, the ratio of the mesopore volume to the pore volume up to 30 nm in diameter was obtained by dividing the mesopore volume obtained by the above method by the pore volume up to 30 nm in diameter.
<Measurement of hardness>
It was measured by the method described in JIS K1474.
<Measurement of decolorization performance>
Add pulverized activated carbon to 50 mL of commercially available soy sauce (registered trademark: Higashi Maru), shake at 25 ° C for 3 hours, filter, measure the absorbance of the filtrate at a wavelength of 460 nm, and obtain the original absorbance (3.8) The absorbance adsorption amount per unit mass of the activated carbon when decolored to 1/10 was calculated.
<Measurement of iodine adsorption performance>
It was determined by the method described in JIS K1474.

  Although the activated carbon of the example has higher soy sauce decolorization performance than the activated carbon of the comparative example, the iodine adsorption performance is suppressed. That is, the activated carbon of the present invention has a selective adsorptive property that the solution can be effectively decolored in the presence of low molecular components.

The activated carbon of the present invention and the adsorbent containing the activated carbon can be effectively decolorized while leaving an active ingredient having a low molecular weight, and thus can be used for purification of an aqueous solution, adjustment of the concentration of the active ingredient, recovery, and the like.
Therefore, it can be suitably used for purification of various aqueous solutions, separation of ingredients, concentration adjustment, etc. in food, beverage factories and chemical factories.

Claims (2)

The mesopore volume per unit volume is 0.06 ml / ml or more, and the activated carbon raw material is carbonized at 500 ° C. or lower and then steam activated , and the pore volume is up to 30 nm in diameter. A method for producing activated carbon having a mesopore volume ratio of 0.3 or more . Using coconut shell as a raw material of activated carbon raw material, manufacturing method of claim 1.