JP2017024963A - Active carbon for liquid phase and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high performance active carbon which is capable of being used for purifying water quality and uses apple pruning branch or the like and a manufacturing method therefor.SOLUTION: There is provided active carbon having a constitution having mesopore volume with 4.2 to 20 nm of 0.1 cm/g or more, high in methylene blue adsorptivity and having specific surface area of 1000 m/g or more. There is provided active carbon for liquid phase obtained by carbonizing and gas activating a raw material without adding chemicals for activation at a specific temperature under specific atmosphere.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a liquid-phase activated carbon and a method for producing the same, and particularly to a highly functional activated carbon having a high methylene blue adsorption characteristic and a method for producing the same, targeting water purification as an application of the activated carbon.

  So far, the applicant has repeatedly studied on the production of activated carbon from tree branches such as apple pruned branches and published the results (Patent Documents 1 to 3 below). Newly, the pore structure of activated carbon prepared by air activation was evaluated by ash analysis, physical properties of the pores and microscopic observation, and compared with cedar activated carbon prepared under the same conditions. It was found that a large number of pores in the range of 4 to 20 nm were generated. This was thought to be because trace metals such as calcium contained acted catalytically on activation and promoted the formation of pores in the above-described range.

  The adsorbent is a substance (porous body) having a large number of voids (pores) inside the particles, and the pores are classified by their diameters. The International Pure and Applied Chemistry Union (IUPAC) defines a diameter of 50 nm or more as a macropore, 2-50 nm as a mesopore, and 2 nm or less as a micropore. In addition, considering the adsorbate molecular diameter and the like, the activated carbon for gas phase such as gas adsorption is concentrated in the micropores, and the activated carbon for liquid phase such as decolorization has many mesopores distributed. Yes.

  Now, radioactive materials were released into the environment due to an accident at a nuclear power plant following the Great East Japan Earthquake, and radioactive iodine and cesium were detected in purified water and tap water. As a means, powdered activated carbon treatment and the like have come to be performed. On the other hand, odorous substances have recently been generated at water purification plants in Aomori Prefecture, and activated carbon is used for the purpose of removing them. In the future, the demand and market for water purification using such activated carbon is expected to expand further.

There have been a considerable number of technical proposals regarding activated carbon and its use. For example, Patent Document 4 listed below discloses air purification, radioactive substance adsorption, iodine trap, methane occlusion, hydrogen occlusion, purified water production, and solvent recovery. , Activated carbon having a volume ratio of 40% or more in the total pore volume of pores (mesopores) having a pore diameter of more than 2.0 nm and less than 50.0 nm for purposes such as decolorization, water treatment and gas masking Has been. Patent Document 5 is characterized in that the specific surface area is 800 to 4000 m ² / g, and the mesopore volume Vm having a pore width of 2.0 nm or more and less than 50 nm is 0.1 to 0.5 cm ³ / g. An activated carbon is disclosed. Further, Non-Patent Document 1 describes that in the case of activated carbon for gas phase such as gas adsorption, it is concentrated in the micropores, and in the case of activated carbon for liquid phase such as decolorization, it is distributed in mesopores.

Japanese Patent Application Laid-Open No. 2011-177656 “Adsorbent material derived from tree branches and method for producing the same” JP 2013-173633 A1 "Activated carbon and manufacturing method thereof" JP 2014-047087 A "Method for producing supported activated carbon, supported activated carbon, and filter using the same" JP 2013-249234 A "Activated carbon and its manufacturing method" 2011-93774 "Activated carbon and its manufacturing method, liquid purification method using the same, and fuel cell system"

Yuzo Sanada, Motoyuki Suzuki, Satoshi Fujimoto: New Edition Activated Carbon Fundamentals and Applications, 8th Edition, Kodansha Scientific, p21 (1997)

As described above, activated carbon used in the liquid phase such as water purification is characterized by the fact that many mesopores are distributed. Such activated carbon is prepared by chemical activation using zinc chloride, phosphoric acid or the like. It is common. But this method
1) Almost all production facilities require corrosion-resistant materials and corrosion-resistant treatments, so capital investment is high and affects production costs 2) Problems such as complicated production processes, difficulty in expanding production scale and automating production have.

  In view of the problems of the prior art and the social background in which the demand for water purification technology using activated carbon is increasing, there are many mesopores distributed using tree branches such as apple pruned branches as waste. There is a need for a technology that enables the production of activated carbon to reduce manufacturing costs while reducing capital investment. There is also a need for a manufacturing technique that can facilitate the expansion of production scale and automation of production by a simpler manufacturing process. By providing such technology, it is possible to contribute to the effective use of resources and the promotion and activation of industries.

  Further, in order to enhance the adsorption characteristics as activated carbon, it is desirable to use activated carbon with a specific pore distribution for each adsorbate, depending on the application. In this regard, each of the above prior art documents does not disclose the use of activated carbon, the range of effective mesopores in individual adsorbates, etc., and the focus is on limiting the pore range with methylene blue adsorption characteristics as Merckmar. Not shown.

  Therefore, the problem to be solved by the present invention is based on the state of the prior art, targeting water purification as an application of activated carbon made from apple pruned branches, or activated carbon from other raw materials, without using chemical activation, In particular, it is to provide a highly functional activated carbon having a high methylene blue adsorption property and a method for producing the same.

  The inventor of the present application has studied the above-mentioned problem with water purification as a target for the use of apple pruned activated carbon. That is, it was confirmed that activated carbon in which many mesopores were distributed by gas activation using tree branches such as apple pruned branches as a raw material. In addition, we measured and compared the basic physical properties of apple pruned activated carbon and commercial products, the pore distribution range involved in the adsorption of methylene blue, which is one of the items in the Japan Water Works Association standard "activated carbon for water supply", and the amount of adsorption As a result, the activation condition for exceeding the standard value was found. And based on this result, it came to complete this invention. That is, the invention claimed in the present application, or at least the disclosed invention, as means for solving the above-described problems is as follows.

[1] A mesoporous volume of 4.2 to 20 nm and a mesopore volume of 0.1 cm ³ / g or more, and a liquid phase activated carbon characterized by high methylene blue adsorption performance.
[1b] is at 4.2722nm than 20nm following mesopore volume 0.1 cm ³ / g or more, and wherein the methylene blue adsorption performance is high, the liquid-phase activated carbon.
[2] The liquid phase activated carbon according to [1] or [1b], wherein the specific surface area is 1000 m ² / g or more.
[3] The liquid phase activated carbon according to any one of [1] to [2], which is obtained by carbonizing and gas activating a raw material without adding a chemical.
[4] The liquid phase activated carbon according to any one of [1] to [3], wherein a tree branch is used as a raw material.

[5] The liquid phase activated carbon according to any one of [1] to [3], wherein the pruned apple branch is used as a raw material.
[6] It is characterized in that activated carbon with high methylene blue adsorption performance with a mesopore volume of 0.1 cm ³ / g or more of 4.2 nm nm or more and 20 nm or less is obtained by carbonization and gas activation of the raw material without adding chemicals. , Liquid phase activated carbon production method.
[6b] It is characterized in that activated carbon with high methylene blue adsorption performance with a mesopore volume of at least 0.1 cm ³ / g of 4.2722 nm nm or more and 20 nm or less is obtained by carbonizing and activating the raw material without adding chemicals. , Liquid phase activated carbon production method.
[7] The method for producing activated carbon for liquid phase according to [6] or [6b], wherein the carbonization and gas activation are performed by a single treatment.

[8] The treatment is a treatment in which the raw material charged in the carbonization activation furnace is heated in a nitrogen gas circulation state, and the water heated when the maximum temperature is reached is included in the nitrogen gas and allowed to flow for a predetermined time or more. The method for producing activated carbon for liquid phase according to [7], wherein the method is a treatment.
[9] The method for producing activated carbon for liquid phase according to [8], wherein the maximum temperature reached is 800 ° C. or higher.
[10] The method for producing activated carbon for liquid phase according to [7] or [9], wherein the predetermined time is 90 minutes or more.
[11] The method for producing activated carbon for liquid phase according to any one of [6] to [10], wherein the raw material is a pruned apple branch.

  Since the liquid phase activated carbon and the method for producing the same of the present invention are configured as described above, according to this, there are many mesopores of 2.4 to 20 nm without using chemical activation, and in particular, methylene blue adsorption characteristics. It is possible to provide a high-performance activated carbon for liquid phase that has improved Moreover, the activated carbon for liquid phase in which many mesopores are distributed can be obtained by a low-cost and simpler manufacturing process, and the expansion of production scale and automation of production can be facilitated.

  Moreover, since it discovered that the hole of 2.4-20 nm raises methylene blue adsorption | suction, it can use not only for a pruning branch of an apple but the activated carbon which used other raw materials as a raw material, and its manufacture. Further, in the present invention using tree branches such as apple pruned branches as raw materials, tree branches such as apple pruned branches as waste can be used as raw materials, which not only can reduce manufacturing costs but also contribute to waste reduction. You can also.

It is the graph which showed the pore distribution of each activated carbon. It is the graph which expanded the principal part of FIG. It is the graph which showed the methylene blue adsorption | suction performance of each activated carbon.

Hereinafter, the present invention will be described in more detail.
The liquid phase activated carbon of the present invention has a mesopore volume of 0.1 cm ³ / g or more of 4.2 nm or more and 20 nm or less and a high configuration of methylene blue adsorption performance. Such a numerical range has been clarified in the research process described later in the examples, and specifically, is based on a pore interval that can be set in the pore distribution measuring apparatus used. More precisely, the lower limit set point is 4.2722 nm, the next set point is 4.8532 nm, and the liquid phase activated carbon has a mesopore volume of 0.1 cm ³ / g or more of any of these and 20 nm or less.

Further, the activated carbon for liquid phase of the present invention has a specific surface area of 1000 m ² / g or more, and is obtained by carbonization and gas activation of raw materials without adding chemicals, that is, chemical activation. Moreover, tree branches such as apple pruned branches can be suitably used as the raw material, but the present invention is not limited to this, and any material can be used as long as it can obtain mesopores with the above characteristics. Can do.

The liquid phase activated carbon production method of the present invention has high methylene blue adsorption performance of 4.2 to 20 nm mesopore volume of 0.1 cm ³ / g or more without adding chemicals by carbonizing and activating the raw material. Activated carbon is obtained, and this carbonization and gas activation can be performed by a single treatment. The raw material is not limited, and tree branches such as apple pruned branches can also be used as described above.

  Carbonization and gas activation treatment is a treatment in which the raw material charged in the carbonization activation furnace is heated in a nitrogen gas circulation state, and when heated to the maximum temperature, the heated water is included in the nitrogen gas and distributed for a predetermined time or more. It is a process to make. A satisfactory result can be obtained by setting the maximum temperature to 800 ° C. or more and setting the predetermined time to 90 minutes or more.

Hereinafter, although the present invention will be described with reference to an example of activated carbon derived from apple pruned branches, the present invention is not limited thereto. In addition, it is set as an Example with the summary description of the research progress leading to completion of this invention.
1. Study on adsorption of methylene blue on activated carbon derived from apple pruned branches Targeting water purification as an application of apple pruned activated carbon, basic physical properties of apple pruned activated carbon and commercial products and one of the items in the Japan Water Works Association standard "activated carbon for water supply" The amount of methylene blue adsorbed was measured and compared.

2. Experimental Method 2.1 Charcoal made from pruned apples as raw material for activated carbon (social welfare corporation, Kiri no Sato Co., Ltd., Aomori Charcoal) was crushed with a hammer and passed through a 0.3-2 mm sieve ( The following: A0) was used. Activation was performed using an activated carbon activation test apparatus (manufactured by Tanaka Tech Co., Ltd., RK-S20). After drying A0 at 105 ° C. for 24 hours, 100 g was charged into a 6 L kiln container.

  Carbonization and gas activation treatment were performed at a kiln container rotational speed of 2.2 rpm and a nitrogen gas flow rate of 1 L / min. In gas activation, when the inside of the kiln container reaches the maximum temperature of 1000 ° C., heat 1.67 mL / min of water at 130 ° C. and allow it to flow while being included in nitrogen gas, and hold for 90 minutes or 120 minutes. It went by. In this way, samples were prepared four times for each condition (hereinafter, gas activation 90 minutes: A2, gas activation 120 minutes: A3).

The yield Y (%) of the apple pruned activated carbon was obtained from the following equation [1] from the mass of the sample before activation: Ws (g) and the mass of the sample after activation: Wc (g), and the average Value.
Y = Wc / Ws × 100 [1]
For comparison, commercially available activated carbon (hereinafter referred to as S1) was used. This was pulverized using Milcer (manufactured by Iwatani Corporation) and used for the test.

2.2 Physical property evaluation of activated carbon The particle diameter of powdered activated carbon was measured using a laser diffraction / scattering particle size distribution measuring device (LA-300, manufactured by Horiba, Ltd.), and the median diameter: Mps (μm) was calculated. . Further, the specific surface area and pore volume of the activated carbon were determined by isothermal adsorption / desorption of nitrogen at −196 ° C. after degassing at 250 ° C. for 5 hours using a specific surface area / pore distribution measuring device (BELSORP-mini manufactured by Nippon Bell Co., Ltd.). A line is measured, specific surface area: S (m ² / g) by BET method, external surface area: So (m ² / g) by t-plot method, micropore volume: VtN (cm ³ / g) The mesopore volume: ViN (cm ³ / g) was calculated by the BJH method. Further, the micropore distribution was calculated by the MP-plot method, and the mesopore distribution was calculated by the BJH plot method.

2.3 Adsorption performance of methylene blue The amount of methylene blue adsorbed was measured according to JISK1474 (activated carbon test method). The amount of adsorption was calculated from the average of three tests for the methylene blue adsorption performance for 1 g of each sample.

3. Results and Discussion 3.1 Basic Physical Properties of Activated Carbon FIG. 1 is a graph showing the pore distribution of each activated carbon, and FIG. 2 is an enlarged graph of the main part of FIG. As described above, activated carbon A2 was prepared with an activation time of 90 minutes, and activated carbon A3 with 120 minutes. When the activated carbon A2 and the commercial product S1 were compared, the commercial product S1 had a higher value than the activated carbon A2 at 2.1 nm, but the value was reversed at 2.4 nm, and thereafter the relationship was maintained. All the activated carbons had almost the same value around 20 nm.

3.2 Adsorption performance of activated carbon FIG. 3 is a graph showing the methylene blue adsorption performance of each activated carbon. The activated carbon A2 and A3 were higher in methylene blue adsorption performance than the commercial product S1. The reason why the adsorption performance is improved is that there are many pores related to the adsorption of methylene blue. Therefore, it is clear that the large number of pores of 2.4 to 20 nm increases the adsorption performance of methylene blue. became.

  In addition, in the “powder activated carbon for water supply” which is a standard of the Japan Water Works Association (JWWA), the methylene blue adsorption amount of powder activated carbon that can be used in actual sites is 150 ml / g. In FIG. 3, the activated carbon A2 with an activation time of 90 minutes was below this value, but the activated carbon A3 with the activation time of 120 minutes was much higher. From this, it became clear that there is an optimal activation time for methylene blue adsorption performance between the activation time of 90 minutes and 120 minutes.

4). Summary (1) It was revealed that activated carbon having a large mesopore volume has high methylene blue adsorption performance.
(2) It was revealed that there are pores affecting methylene blue adsorption between 2 nm and 2.4 nm.
(3) Especially, the methylene blue adsorption performance of apple pruned activated carbon with an activation time of 120 minutes showed a value exceeding the standard of powdered activated carbon for water supply.

According to the activated carbon for liquid phase and the method for producing the same of the present invention, a highly functional activated carbon for liquid phase having many mesopores of 2.4 to 20 nm and particularly improved methylene blue adsorption characteristics without using chemical activation Can be provided. Moreover, the activated carbon for liquid phases in which many mesopores are distributed can be obtained by a low-cost and simpler manufacturing process. Therefore, it is an invention with high industrial applicability in all fields related to activated carbon / adsorbent production and water treatment technology and all other related fields.

Claims (11)

A liquid phase activated carbon having a mesopore volume of 0.1 cm ³ / g of 4.2 nm to 20 nm and a high methylene blue adsorption performance. ^{2. The} activated carbon for liquid phase according to claim 1, wherein the specific surface area is 1000 m ² / g or more. 3. The activated carbon for liquid phase according to claim 1, which is obtained by carbonizing and activating a raw material without adding chemicals. 4. The activated carbon for liquid phase according to any one of [1] to [3], wherein a tree branch is used as a raw material. The activated carbon for liquid phase according to any one of claims 1 to 3, wherein a pruned apple branch is used as a raw material. By carbonizing the raw material and activating the gas, it is possible to obtain activated carbon having a high methylene blue adsorption performance with a mesopore volume of 0.1 cm ³ / g or more of 4.2 nm nm or more and 20 nm or less without adding chemicals. Activated carbon manufacturing method. The method for producing activated carbon for liquid phase according to claim 6, wherein the carbonization and gas activation are performed by a single treatment. The treatment is a treatment in which the raw material charged in the carbonization activation furnace is heated in a nitrogen gas circulation state, and is a treatment in which the heated water is included in the nitrogen gas when the maximum temperature is reached and is circulated for a predetermined time or more. The method for producing activated carbon for liquid phase according to claim 7, wherein: The method for producing activated carbon for liquid phase according to claim 8, wherein the maximum temperature reached is 800 ° C or higher. The method for producing activated carbon for liquid phase according to claim 8 or 9, wherein the predetermined time is 90 minutes or more. The method for producing activated carbon for liquid phase according to any one of claims 6 to 10, wherein the raw material is a pruned apple branch.