JPH11240707A - Activated carbon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an activated carbon having both of an effective absorbing property for a low molecular compound and an effective absorbing property for a high molecular compound. SOLUTION: This activated carbon has 30-2,500 m<2> /g specific surface area of pores having >=20 Å diameters, and 600-2,500 m<2> /g specific surface area of pores having <20 Å diameters. The activated carbon is, for example, formed into a fibrous shape. The activated carbon is utilized as a material for removing musty smell and trihalomethane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to activated carbon, and more particularly to activated carbon useful as an adsorbent.

[0002]

2. Description of the Related Art Recently, water quality of tap water sources has been deteriorating due to eutrophication and the like. For example, it has been confirmed that raw materials contain organic substances such as humic substances. I have. Such organic substances are recognized as causing off-flavors typified by so-called "mold odor" or reacting with residual chlorine added for disinfection of raw water to produce carcinogenic trihalomethane. Therefore, an attempt has been made to treat raw water with activated carbon in a water purification facility such as a rapid filtration device or a chlorination device, thereby adsorbing and removing organic substances.

[0003] Activated carbon used in such water purification equipment is a carbon material having a porous structure developed from a large number of pores, and its adsorption performance is not determined only by the size of the pore volume. It greatly depends on the relationship between the size of the molecule to be adsorbed and the size of the pore diameter. For example,
When the main purpose is to adsorb and remove the above-mentioned high molecular compounds such as humic substances, generally activated carbon having a large pore diameter is preferably used, and conversely, the adsorption and removal of low molecular weight compounds such as trihalomethane and various odorous substances, and vapor removal. When the main purpose is to adsorb and remove the substance to be adsorbed in the phase, activated carbon having a small pore diameter is preferably used.

However, the pore size and pore size distribution of activated carbon are usually determined by the selection of the raw material (eg, carbonaceous raw material such as coconut shell, sawdust, coal, etc.) and the method of activation. For example, when wood-based raw materials such as coconut shells and sawdust are used, activated carbon with a small pore size suitable for adsorption and removal of low-molecular compounds can be obtained, while when using coal-based raw materials, high-molecular compound adsorption can be obtained. Activated carbon with a large pore diameter suitable for removal can be obtained. Therefore, it is difficult for the conventional activated carbon to simultaneously exhibit effective adsorption and removal performance for low molecular weight compounds and effective adsorption and removal performance for high molecular weight compounds.

An object of the present invention is to realize an activated carbon having both effective adsorption and removal performance for low molecular weight compounds and effective adsorption and removal performance for high molecular weight compounds.

[0006]

The activated carbon of the present invention has a specific surface area of pores having a diameter of 20 angstroms or more of 30 m or more.
² / g or more and 2,500 m ² / g or less and a diameter of 20
The specific surface area of pores smaller than Å is 600 m ² /
g to 2,500 m ² / g.

Here, the activated carbon is formed in, for example, a fibrous form.

[0008] The activated carbon of the present invention is suitable, for example, as a material for removing mold odor and trihalomethane.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The activated carbon of the present invention has a developed porous structure composed of a large number of pores. The specific surface area of pores having a diameter of 20 Å or more is 30 m ² / g or more and 2,500 m ^2. / G or less, preferably 100 m ² / g or more and 2,500 m ² / g or less, more preferably 1,200 m ² / g or less.
m ² / g or more and 2,500 m ² / g or less. When the specific surface area is less than 30 m ² / g, it becomes difficult to effectively adsorb and remove the polymer compound. Conversely, 2,500 m ²
/ G or more, there is a possibility that the strength of the activated carbon itself may be lowered, and the yield is low and the production becomes difficult.

Further, the activated carbon of the present invention have a diameter of the specific surface area of pores less than 20 angstroms is 600 meters ² / g or more 2,500 m ² / g or less, preferably 1,000 m ² /
g or more and 2,500 m ² / g or less, more preferably 1.5 or less.
It is not less than 00 m ² / g and not more than 2,500 m ² / g. When the specific surface area is less than 600 m ² / g, it becomes difficult to effectively adsorb and remove low-molecular compounds. Conversely, 2,50
If it is 0 m ² / g or more, the strength of the activated carbon itself may be reduced, and the production is difficult due to a low yield.

The shape of the activated carbon of the present invention is not particularly limited, and may be formed into various shapes such as a granular shape and a fibrous shape.

The activated carbon of the present invention as described above can be prepared, for example, by the following production process. First,
The organometallic compound and the activated carbon precursor are mixed in a solvent to obtain a mixture. Examples of the organometallic compound used here include, for example, an yttrium compound, a titanium compound, a zirconium compound, a ytterbium compound, a samarium compound, a vanadium compound, a manganese compound, an iron compound,
Mention may be made of magnesium compounds and neodymium compounds.

Here, examples of the yttrium compound include yttrium acetylacetonate, triscyclopentadienyl yttrium, yttrium naphthoic acid, yttrium isopropoxide, trisacetylacetonatodiaquoytrium and the like. Examples of the titanium compound include titanium oxoacetylacetonate. Examples of the zirconium compound include zirconium acetylacetonate. Examples of the ytterbium compound include ytterbium iodide and triscyclopentadienyl. Examples of the samarium compound include samarium isopropoxide and samarium acetylacetonate. Further, examples of the neodymium compound include triscyclopentadienyl neodymium and neodymium acetylacetonate.

Preferred among the above-mentioned organometallic compounds are yttrium compounds, titanium compounds and zirconium compounds in that the effect of controlling pores formed in the activated carbon is high. Incidentally, two or more kinds of the above-mentioned various organometallic compounds may be used in combination.

On the other hand, the activated carbon precursor used here is:
Activated carbon can be easily obtained by a method such as carbonization or infusibilization, and is not particularly limited as long as it can be mixed with the above-mentioned organometallic compound and a solvent. Specific examples include those generally used for producing activated carbon, such as polyacrylonitrile, polyvinyl alcohol, phenolic resin, and pitch. Among them, it is preferable to use the pitch in that the theoretical carbonization yield during carbonization is good.

When preparing a fibrous activated carbon,
It is preferable to use an activated carbon precursor having a degree of polymerization that can be spun or an activated carbon precursor that can increase the degree of condensation to an extent that can be spun by air-blowing treatment described later.

The solvent used for mixing the above-mentioned organometallic compound and the above-mentioned activated carbon precursor is not particularly limited as long as it can dissolve both the organometallic compound and the activated carbon precursor. And various known ones. Specifically, quinoline, tetrahydrofuran, dichloromethane, benzene, toluene, xylene and the like can be exemplified. In addition, such a solvent can be appropriately selected according to the type of the organometallic compound and the activated carbon precursor to be used.

When the above-mentioned organic metal compound and the activated carbon precursor are mixed using the above-mentioned solvent, a method in which the activated carbon precursor is added to and mixed with a solvent in which the organometallic compound is dissolved in advance, and a method in which the activated carbon precursor is mixed A method in which a solvent in which an organometallic compound is previously dissolved is added and mixed therein can be employed. In such a mixing operation, operations such as stirring and heating may be appropriately added to achieve uniform mixing.

When preparing the above-mentioned mixture containing the organometallic compound, the activated carbon precursor and the solvent, the amount of the metal is usually 0.01 to 5% by weight of the activated carbon precursor, preferably 0.1 to 2% by weight. %, More preferably 0.2 to 0.5% by weight, the mixing ratio of the organometallic compound and the activated carbon precursor is set. The amount of metal referred to here is not an amount as an organometallic compound but an amount in terms of a metal element.

When this proportion is less than 0.01% by weight,
In some cases, the above-described porous structure is difficult to be formed in the obtained activated carbon, and as a result, the activated carbon may not be able to exhibit required adsorption removal performance for both the low-molecular compound and the high-molecular compound. is there. On the other hand, when the content exceeds 5% by weight, the metal tends to aggregate in the obtained activated carbon, so that the porous structure as described above is difficult to be formed. As a result, the activated carbon is a low molecular weight compound and a high molecular weight compound. It may be difficult to exhibit the required adsorption removal performance for both. Further, when the intended activated carbon is formed into a fibrous form, the spinnability of the above mixture may be impaired.

Incidentally, when the proportion of the organometallic compound increases, the average pore diameter generally increases.

Next, the above-mentioned mixture (hereinafter referred to as an activated carbon precursor mixture) is subjected to a carbonization treatment or an infusibilization treatment,
Alternatively, both the infusibilization treatment and the carbonization treatment are performed, and then the activation treatment is further performed. At this time, it is preferable to remove the solvent from the activated carbon precursor mixture in advance. As a method for removing the solvent, conventional means such as distillation under reduced pressure can be employed.

The carbonization method, the infusibilization method and the activation method of the activated carbon precursor mixture can be carried out according to a conventional method, and are not particularly limited. For example, in the carbonization treatment, the activated carbon precursor mixture is heated to about 800 to 1,200 ° C. at a rate of about 5 to 10 ° C. per minute under an inert gas atmosphere such as nitrogen, and the maximum temperature at that time is increased. This can be achieved by maintaining for up to 10 minutes. On the other hand, in the infusibilization treatment, the activated carbon precursor mixture is heated from a temperature lower than its melting point to a temperature of not more than 0.1 mg / min in an inert gas atmosphere or an oxygen-containing gas atmosphere.
It can be achieved by heating to about 400 ° C. at a rate of about 1 to 5 ° C. Further, the activation treatment is performed in a gas atmosphere in which steam, carbon dioxide, oxygen, a mixture thereof, or a gas obtained by diluting these gases with an inert gas such as nitrogen is subjected to carbonization treatment, infusibilization treatment, or both treatments. 800 to 1,2
This can be achieved by heating to about 00 ° C. and holding for about 5 to 120 minutes.

When preparing a fibrous activated carbon,
Before applying the above-described carbonization treatment step or the like, the activated carbon precursor mixture is spun in advance. In this case, it is preferable that the activated carbon precursor mixture is subjected to an oxygen-containing gas blowing treatment (air blowing treatment) as necessary to increase the degree of polymerization (condensation degree) of the activated carbon precursor so that the activated carbon can be spun. .

The porous structure peculiar to the activated carbon of the present invention can be obtained by selecting or combining an organometallic compound, a mixing ratio of the organometallic compound and the activated carbon precursor, an activation temperature and an activation treatment time in the above-mentioned production method. , That is, the yield (= weight of carbon material after activation / weight of carbon material before activation) is appropriately set. For example,
When the activation degree is increased by appropriately setting the activation treatment conditions, the generation of pores having a large average pore diameter tends to increase, whereby the specific surface area of pores having a diameter of 20 angstroms or more is set to a required range. can do.

Since the activated carbon of the present invention has a porous structure set as described above, it has large pores suitable for the adsorption of high molecular compounds and small pores suitable for the adsorption of low molecular compounds. And holes at the same time. For this reason, this activated carbon
Good adsorption removal properties can be exhibited for both low molecular weight compounds and high molecular weight compounds. Therefore, if this activated carbon is used for purification of tap water, various substances contained in tap water, for example, low-molecular compounds such as trihalomethane and various odorous substances, and organic substances such as humic substances that cause mold odor are represented. And the like can be effectively adsorbed and removed simultaneously alone. In other words, the activated carbon of the present invention can be preferably used as a water purification material for removing mold odor and trihalomethane.

[0027]

EXAMPLES Examples 1 to 3 and Comparative Examples 1 and 2 Coal tar 1, from which water and quinoline insolubles were removed.
100 g was heated to 80 ° C. under a nitrogen atmosphere, and trisacetylacetonatodiaquoytrium [Y (CH ₃
COCHCOCH ₃₎ the ₂ · 2H ₂ O] quinoline were dissolved 4.0 g 100 ml stirred slowly dropwise added to 5 hours.

Next, this was distilled under reduced pressure, and then reacted at 330 ° C. for 3 hours while blowing air at a rate of 5 l / min to obtain a yttrium-containing coal tar pitch which was a mixture of activated carbon precursors.

The activated carbon precursor mixture thus obtained is charged into a spinner having a nozzle diameter of 0.3 mm, and is spun at a winding speed of 150 m / sec while being heated to a pitch melting temperature. Thus, a pitch fiber was obtained.

The obtained pitch fiber was heated from room temperature to 375 ° C. at a rate of 2 ° C./min in an air atmosphere, and kept at that temperature for 15 minutes to perform infusibility treatment. afterwards,
The infusibilized pitch fiber was activated under the conditions shown in Table 1 in a nitrogen gas atmosphere containing water vapor.

With respect to the fibrous activated carbon thus obtained, the total specific surface area, the specific surface area of mesopores (pores having a diameter of 20 Å or more), the mesopore ratio, and the average pore diameter were examined. Here, the specific surface area, the mesopore specific surface area, and the pore diameter are defined as nitrogen gas adsorption isotherm (BET-BJH) on the adsorption side at the boiling point of liquid nitrogen under normal pressure.
Method). The mesopore volume ratio was determined based on the volume of mesopores having diameters of 20 to 500 angstroms, which was obtained by subtracting the volume of cumulative micropores having pore diameters of less than 20 angstroms from the total pore volume. Table 1 shows the results.

[0032]

[Table 1]

Evaluation The moldy odor adsorption test and the trihalomethane adsorption test described below were performed on the fibrous activated carbon obtained in Examples 1 to 3 and Comparative Examples 1 and 2. The results are shown in FIG. 1 and FIG.

(Mold Odor Adsorption Test) A mold odor, 2-methylisoborneol (2-MIB), was dissolved in methanol to prepare a primary stock solution. After diluting this primary stock solution with methanol, it was dissolved in ultrapure water, and the concentration of 2-MIB was 500 μm.
g / l of raw water was prepared.

A plurality of Erlenmeyer flasks each containing 200 ml of the raw water were prepared, and each of the Erlenmeyer flasks except for one Erlenmeyer flask was individually charged with the fibrous activated carbon of each Example and each Comparative Example. In this state, place the Erlenmeyer flask at 25 ° C.
And shaken for 24 hours. Then, the raw water in each Erlenmeyer flask was collected and the concentration of 2-MIB was analyzed to obtain an adsorption isotherm of 2-MIB shown in FIG.

(Trihalomethane Adsorption Test) Chloroform, a kind of trihalomethane, was dissolved in methanol, and
The next stock solution was used. After diluting this primary stock solution with methanol, it is dissolved in ultrapure water and the concentration of chloroform is 308 ppb.
Was prepared.

A plurality of Erlenmeyer flasks containing 120 ml of this raw water were prepared, and the fibrous activated carbon of each Example and Comparative Example 1 was individually placed in each of the other Erlenmeyer flasks except one Erlenmeyer flask. In this state, place the Erlenmeyer flask at 20 ° C.
And shaken for 24 hours. Thereafter, the raw water in each Erlenmeyer flask was collected and the concentration of chloroform was analyzed to obtain the adsorption isotherm of chloroform shown in FIG.

1 and 2 that the fibrous activated carbons of Examples 1 to 3 were 2-
It can be seen that good adsorption performance is exhibited for both MIB and chloroform.

[0039]

Since the activated carbon of the present invention has the above-mentioned porous structure, it has both effective adsorption and removal performance for low molecular weight compounds and effective adsorption and removal performance for high molecular weight compounds. I have.

[Brief description of the drawings]

FIG. 1 is a graph showing the results of a mold odor adsorption test in Examples.

FIG. 2 is a graph showing the results of a trihalomethane adsorption test in Examples.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tatsuo Katayama 5 Uji Tonouchi, Uji City, Kyoto Prefecture Ador Co., Ltd. (72) Takeshi Maeda 4-1-2, Hirano-cho, Chuo-ku, Osaka City, Osaka Osaka Gas Stock Inside the company (72) Inventor Takuya Ueno 4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Inside Osaka Gas Co., Ltd. (72) Inventor Shigeji 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka No. Osaka Gas Co., Ltd. (72) Inventor Takeshi Kondo 23 Uji Kozakura, Uji-city, Kyoto Pref.

Claims (3)

[Claims] The pores having a diameter of 20 Å or more have a specific surface area of 30 m ² / g or more and 2,500 m ² / g or less, and the pores having a diameter of less than 20 Å have a specific surface area of 600 m ² / g or more. Activated carbon of not more than 500 m ² / g. 2. The activated carbon according to claim 1, which is formed in a fibrous form. 3. The activated carbon according to claim 1, which is a material for removing mold odor and trihalomethane.