JP3013275B2 - Method for modifying carbonaceous fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for modifying carbon fiber.

[0002] In this specification, "%" means
It means “% by weight”.

[0003]

2. Description of the Related Art In recent years, tap water contains trace amounts of organic substances as a result of pollution of rivers, lakes and marshes by industrial water, municipal sewage and the like. These organic substances cause the mold odor of tap water, and some of them react with chlorine to generate harmful substances (eg, trihalomethane) which are said to have carcinogenicity. Therefore, it is necessary to perform more advanced processing in the future.

[0004] As a typical example of the advanced water treatment method, an activated carbon treatment method is known. Recently, it has been attempted to carry out water treatment using a low-priced, high-adsorbing-pitch fibrous activated carbon (hereinafter referred to as ACF unless otherwise required) in place of the granular activated carbon used so far. . In particular, JP-B-63-67566 discloses magnesium, calcium, barium, carbonaceous fibers having a surface area of 30 to 1200 m ² / g and a pore diameter of 30 to 300 angstroms and a pore volume of 0.1 cc / g or less. Method for producing activated carbon fiber in which at least one compound of iron, cobalt, nickel and manganese is supported, and the activated carbon fiber is subjected to a heat treatment at 650 to 1050 ° C. in an oxidizing gas or a combustion waste gas to be activated. And shows that the pore volume increases from 30 to 300 angstroms in pore diameter after treatment. However, since many precursors of trihalomethane (hereinafter referred to as THM) have relatively large molecular weights, the ACF generally has a large proportion of micropores having a radius of 10 Å or less.
Then, sufficient adsorption removal of the THM precursor cannot be performed. Further, it is difficult to increase the number of pores having a pore diameter of 20 to 300 Å by the method disclosed in the above document. In particular, with regard to pitch-based ACF, it has been found that it is impossible to increase the number of pores of 20 to 300 Å by the method described in the above document.

[0005]

Accordingly, the present invention provides a T
A main object of the present invention is to provide a method for producing an ACF capable of effectively removing and removing an HM precursor.

[0006]

Means for Solving the Problems The present inventor has conducted various studies in view of the state of the art as described above, and as a result, has performed a hydrophilization treatment with an oxidizing agent on a carbonaceous fiber, and specified a specific substance as a catalyst. After activation, when activating by steam,
It has been found that pores (mesopores) having a radius of about 15 to 150 angstroms are increased to obtain a modified ACF capable of sufficiently adsorbing and removing the THM precursor.

That is, the present invention provides the following method for modifying carbonaceous fibers: "Specific surface area 0.1 to 1".
A method for modifying carbonaceous fiber, comprising: performing a hydrophilization treatment with an oxidizing agent on 200 m ² / g of carbonaceous fiber, and then carrying an activation treatment by supporting an alkaline earth metal. "
The carbonaceous fiber used as a raw material in the present invention is a carbonaceous fiber having a specific surface area of 0.1 to 1200 m ² / g by a BET method.

In the present invention, first, the carbon fiber is subjected to a hydrophilic treatment (oxidation treatment of the surface of the carbon fiber) with an oxidizing agent, and then an alkaline earth metal is carried thereon to perform an activation treatment. Examples of the oxidizing agent include sodium hypochlorite, potassium hypochlorite, hydrogen peroxide, and chlorine gas (containing moisture). Examples of the alkaline earth metal source include calcium acetate, calcium formate, and calcium oxalate. , Barium acetate, barium acetate, calcium citrate and the like. The method of treatment with the oxidizing agent and the method of applying the alkaline earth metal are not particularly limited, but a method of immersing the carbonaceous fiber in an aqueous solution containing the same under normal pressure or reduced pressure, including the method of including the carbonaceous fiber There are a method of immersing in an aqueous solution under normal pressure or reduced pressure and boiling, and a method of spraying an aqueous solution containing these on carbonaceous fibers. Hydrophilic treatment with an oxidizing agent such as sodium hypochlorite (hereinafter, unless otherwise required, simply sodium hypochlorite) and treatment of an alkaline earth metal such as calcium acetate (hereinafter, simply referred to as calcium acetate unless otherwise required) It is more preferable that the carbon fiber is immersed in an aqueous solution of sodium hypochlorite under normal pressure, boiled, and then immersed in an aqueous solution of calcium acetate.

The amount of the oxidizing agent applied to the carbonaceous fiber and the amount of the alkaline earth metal carried can vary depending on the degree of modification of the carbonaceous fiber.
Sodium hypochlorite (effective chlorine 5% or more) 1 to 25%
Calcium acetate (as Ca) is in the range of about 0.1 to 2%. When the amount of sodium hypochlorite is too small, the surface of carbon is not sufficiently hydrophilized, so that the amount of Ca supported as a catalyst decreases, and the reaction rate of the activation treatment decreases. At this time, when the activation temperature is increased to increase the reaction rate, the yield of the modified ACF decreases. On the other hand, if the amount of sodium hypochlorite is too large, the strength of the modified ACF may decrease. On the other hand, if the amount of calcium acetate is too small,
Mesopores cannot be sufficiently opened, and only micropores increase. If the amount of calcium acetate is too large, erosion of the carbon surface will occur other than at the opening of the fine pores, which causes a problem of a decrease in the yield and a decrease in the strength of the modified ACF.

Next, the carbonaceous fiber treated with the oxidizing agent and carrying the alkaline earth metal as described above is subjected to activation treatment with steam. The steam activation treatment for this reforming may be performed according to a conventional method, and is not particularly limited. For example, a carbonaceous fiber treated with an oxidizing agent and carrying an alkaline earth metal is contained in a container. After the air in the container is replaced with an inert gas (such as He, Ar, or N ₂ ), the temperature is raised to about 400 to 900 ° C., and then steam is introduced. Hold for about a minute.

The modified carbonaceous fiber can be
Demineralized by acid washing or the like, and washed to obtain the desired product.

According to the method of the present invention, the conditions of the oxidizing agent treatment,
By appropriately adjusting the amount of alkaline earth metal carried, the activation conditions, and the like, carbonaceous fibers having various pore characteristics can be produced. For example, when performing the adsorption removal of the THM precursor, the pore volume of a mesopore having a pore diameter of about 15 to 150 Å is 0.25 to 0.6 c.
What is necessary is just to produce a modified carbonaceous fiber of about c / g. In addition, other uses (catalyst carrier, material for removing and removing harmful gas in gas phase, material for removing and removing harmful components in liquid phase, etc.)
The modified carbonaceous fibers having different pore characteristics can also be obtained depending on the conditions.

[0013]

According to the present invention, a novel means of first treating raw carbonaceous fiber with an oxidizing agent is used.
A modified carbonaceous fiber having pore characteristics suitable for adsorption removal of the M precursor is obtained. Such a modified carbonaceous fiber is particularly suitable for advanced treatment of tap water.

According to the present invention, the pore characteristics of the carbonaceous fiber can be arbitrarily adjusted by appropriately adjusting the conditions of the oxidizing agent treatment, the supported amount of the alkaline earth metal, the activation conditions, and the like. Modified carbonaceous fibers suitable for uses other than tap water treatment can also be produced.

[0015] Furthermore, the method of the present invention is characterized in that 0.1 m ² /
This is useful because it can modify carbonaceous fibers having an extremely small surface area of about g.

[0016]

EXAMPLES Examples and experimental examples will be shown below to further clarify the features of the present invention.

Example 1 ACF (trade name "A-10", manufactured by Ador Co., Ltd., BET)
The pore volume of pores having a specific surface area of 1080 m ² / g and a radius of 10 angstrom or less is determined by the total method.
3 g of 57 ml / g (95%) is immersed in 400 ml of a 1.8% aqueous solution of sodium hypochlorite (effective chlorine 5% or more), boiled at 100 ° C. for 20 minutes, and then placed in a 4.8% aqueous solution of calcium acetate. Immersion for 5 minutes and put under reduced pressure condition to allow the calcium component to be adsorbed on the pores in the ACF.
CF was subjected to centrifugal dehydration. As a result, 3.0% of calcium acetate was supported on the ACF.

Next, the ACF treated as described above
Was placed in a tubular furnace, and the inside of the furnace was replaced with He. Then, the temperature was started. When the temperature in the tube reached 600 ° C., steam was introduced, and 95% of steam was introduced under the conditions of a partial pressure of steam of 50% and 700 ° C. For 5 minutes, then immersed in a diluted hydrochloric acid solution, left for 12 hours, and further boiled in deionized water.
Decalcification was performed to obtain 1.9 g of the modified ACF of the present invention.

The modified ACF thus obtained has a specific surface area of 1100 m ² / g, and the pore volume of mesopores having a radius of 15 to 150 Å is the total pore volume (1.
0 ml / g).

Experimental Example 1 0.2 g of the modified ACF obtained in Example 1 was added to 120 ml of molasses-phosphate buffer, and the mixture was shaken at 60 ° C. for 60 minutes to adsorb molasses, and the filtrate was subjected to membrane filtration. UV filtrate
When the chromaticity was measured by ( _E420 ) and the decolorization rate was obtained,
90% or more. The bleaching ratio similarly obtained for the ACF before the modification was 2.3%.

Since molasses molecules are known to be adsorbed by pores having a radius of 14 Å or more, the above results indicate that the pore properties of ACF are significantly improved by the method of the present invention. it is obvious.

Experimental Example 2 Aluminum sulfate was added as a coagulant at a ratio of 40 ppm as aluminum to Edogawa river water, subjected to coagulation sedimentation treatment, and then filtered.

Next, 300 ml of the above treated water was placed in an Erlenmeyer flask, and the modified ACF30 obtained in Example 1 was added thereto.
After adding mg, the Erlenmeyer flask was stoppered tightly,
The mixture was stirred with a magnetic stirrer for an hour to adsorb the THM precursor contained in the treated water.

Next, the modified A
When the adsorption performance of the THM precursor by CF was measured, it was 340 μg / g. T by ACF before reforming
Since the adsorption performance of the HM precursor (forming ability) was 60 μg / g, it is clear that the adsorption performance of the THM precursor was significantly improved.

The concentration of the THM precursor in the raw water used in the experiment was 43 μg / l.

Example 2 A pitch-based carbonaceous fiber having a specific surface area of 0.2 m ² / g by a BET method was put into a cylindrical furnace, and the air in the furnace was replaced with He.
The temperature was raised and heat treatment was performed at 700 ° C. for 10 minutes. The heat-treated pitch-based carbonaceous fiber is immersed in a 5% aqueous sodium hypochlorite solution, boiled at 100 ° C. for 20 minutes, and then immersed in a 9.6% aqueous calcium acetate solution for 15 minutes. Was carried.

Next, the pitch-based carbonaceous fiber treated as described above is put into a tubular furnace, and the inside of the furnace is replaced with He. Then, the temperature is increased. When the temperature in the tube reaches 600 ° C., Water vapor was introduced, and the temperature was maintained at 820 ° C. in the furnace for 120 minutes to perform an activation reforming treatment, thereby obtaining a modified carbonaceous fiber of the present invention.

Experimental Example 3 0.2 g of the modified carbonaceous fiber obtained in Example 2 was added to 120 ml of molasses-phosphate buffer, the molasses was adsorbed at 60 ° C. for 60 minutes, and the filtrate was subjected to membrane filtration. And the filtrate was UV (E
₄₂₀ ), the chromaticity was measured, and the decolorization rate was determined.
It was 6.8% or more.

From the above results, it is apparent that the pore characteristics of the carbonaceous fiber are significantly improved by the method of the present invention.

Example 3 (A) A carbonaceous fiber (A) having a specific surface area of 1050 m ² / g by a BET method was kept in a hydrogen gas at 800 ° C. for 80 minutes, cooled, and cooled to 0.6% of calcium acetate (as Ca). %
After Ca was immersed in the solution for 10 minutes to carry Ca, steam reforming was performed under the conditions shown in Table 1 to obtain ACF (B).

(B) Specific surface area by BET method 1050
m ² / g of carbonaceous fiber (A) was immersed in a 0.6% solution of calcium acetate (as Ca) for 10 minutes to carry Ca, then steam reformed under the conditions shown in Table 1, and ACF
(C) was obtained.

(C) Specific surface area of 1050 by BET method
m ² / g carbonaceous fiber (A) is immersed (hydrophilized) in 0.1% hydrogen peroxide solution at 100 ° C. for 20 minutes and then in a 0.6% solution of calcium acetate (as Ca) for 10 minutes After immersion to carry Ca, steam reforming was performed under the conditions shown in Table 1 to obtain ACF (D).

(D) Specific surface area by BET method 1050
m ² / g carbonaceous fiber (A) is immersed in a 20% aqueous sodium hypochlorite solution at 100 ° C. for 20 minutes (hydrophilization treatment)
Then, the resultant was immersed in a 0.6% solution of calcium acetate (as Ca) for 10 minutes to carry Ca, and then subjected to steam reforming under the conditions shown in Table 1 to obtain ACF (E).

The four types of ACF thus obtained were subjected to the same test as in Example 3 to measure the molasses decolorization rate.
Table 1 also shows the results of the yield and the decolorization rate.

Table 1 Activation temperature x time yield Molasses decolorization rate (° C) (min) (%) (%) ACF (A)--2.3 ACF (B) 840 x 150 65.0 10.7 ACF (C) 830 × 150 66.2 27.2 ACF (D) 815 × 150 66.8 39.1 ACF (E) 740 × 87 61.8 99.0 From the results shown in Table 1, Ca was added to the ACF. After activation (see ACF (B) to (E)), AC
It is clear that the molasses decolorization rate of F is improved.

In the case where a hydrophilization treatment is performed in advance using an oxidizing agent prior to the application of Ca (ACF (D)
And (E)), the molasses decolorization rate is higher than when no hydrophilization treatment is performed (see ACF (B) and (C)), and activation can be performed at low temperature and in a short time. it is obvious.

────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI D06M 11/44 D06M 7/00 A D06M 101: 04 11/00 B (72) Inventor Tadahiro Mori 23 Uji Kozakura, Uji City, Kyoto Unitika (72) Inventor Keizo Kajioka 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka Osaka Gas Co., Ltd. (56) References JP-A-59-1771 (JP, A) Akira Tokubo 63-67566 (JP, B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) D01F 9/12-11/16

Claims (1)

(57) [Claims] A carbonaceous fiber characterized in that a carbonaceous fiber having a specific surface area of 0.1 to 1200 m ² / g is subjected to a hydrophilization treatment with an oxidizing agent, and then an alkaline earth metal is carried thereon to perform an activation treatment. For improving the quality of fiber.