JP3122206B2 - Filler for water purifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filler for a water purifier, comprising a specific fibrous activated carbon. Particularly, the present invention relates to a filler for a water purifier suitable for removing trihalomethane in tap water.

[0002]

2. Description of the Related Art Although a small amount of trihalomethane is dissolved in tap water, it has been suspected that trihalomethane itself is a carcinogenic substance. The presence of trihalomethane has been highlighted. Trihalomethane is a generic term for organic compounds in which three of the four hydrogen atoms of methane have been replaced with halogens, and includes chloroform, bromoform, bromodichloromethane, dibromochloromethane, etc. in tap water. Chloroform accounts for about 40-50% of the contained trihalomethane.

[0003] It is known that this trihalomethane is produced by a reaction between humic substances contained in raw tap water and chlorine used for sterilization, and a process of sterilizing tap water with a chlorine-based disinfectant is known. At present, it is extremely difficult to prevent this from happening. Therefore, removal of trihalomethane generated in tap water has become an important issue.

[0004] Conventionally, for the purpose of removing trihalomethane from water, the use of various types of activated carbon, such as granules, powders, and fibers, has been proposed. Japanese Patent Application Laid-Open No. Sho 62-15
As described in Japanese Patent No. 2533, among these activated carbons, fibrous activated carbon is said to have a high ability to remove trihalomethane.

However, conventional activated carbons including the above-mentioned fibrous activated carbon have the following disadvantages. (1) The concentration of trihalomethane contained in tap water is usually very low, usually several tens of ppb, and the concentration of trihalomethane is not so high. (2) Humic substances, which are precursors of trihalomethane contained in tap water, and chlorine used as a bactericide react on the activated carbon surface to reduce the production of trihalomethane. It has the drawbacks that it may promote (3) the ability to remove chloroform, which accounts for the majority of the trihalomethanes contained in tap water, is low. It has not been developed yet.

[0006]

In view of the above, the present inventors have conducted research for the purpose of obtaining an activated carbon having a high trihalomethane removing ability without the above-mentioned disadvantages (1) to (3). . As a result, together with the surface area of the activated carbon, the diameter of the pores in the activated carbon, and the volume ratio occupied by specific micropores and the distribution state thereof are all greatly involved in the trihalomethane removal ability of the activated carbon, and In order to obtain activated carbon with high trihalomethane removal ability without the drawbacks of the above, it is recommended that the surface area of activated carbon, the diameter of pores in activated carbon, and the volume ratio occupied by specific micropores and the ratio be specified. Thus, the present invention has been completed.

That is, according to the present invention, (a) the specific surface area is 8
(B) the cumulative pore volume occupied by pores having a pore radius of 9 ° or less measured by the water vapor adsorption method is 0.1 m ² / g or more.
(C) The cumulative pore volume occupied by pores having a pore radius of 9 ° or less measured by a water vapor adsorption method is 20 cc / g or more and the cumulative pore volume occupied by pores having a pore radius of 100 ° or less is 50%.
% Or more of fibrous activated carbon.

The term “specific surface area” (hereinafter referred to as “SA”) (m ² / g) in the present invention refers to a value determined by a BET method using a nitrogen gas adsorption isotherm at the temperature of liquid nitrogen. In addition, “cumulative pore volume occupied by pores having a pore radius of 9 ° or less measured by a water vapor adsorption method” (hereinafter referred to as “V ₉ ”)
(Cc / g) and measured by the same method.
The “cumulative pore volume occupied by the following pores” (hereinafter referred to as “V ₁₀₀ ”) (cc / g) is defined based on a pore distribution curve prepared by the following method.

[Method of Creating Pore Distribution Curve] Since the equilibrium water vapor pressure of an aqueous sulfuric acid solution having a constant concentration takes a constant value, there is a uniform relationship between the sulfuric acid concentration of the aqueous sulfuric acid solution and the equilibrium water vapor pressure. The fibrous activated carbon is put into the gas phase of the adsorption chamber in which a sulfuric acid aqueous solution having a predetermined concentration is present, and is brought into contact with steam under the condition of 1 atm (absolute pressure) and 30 ° C. The saturated adsorption amount (weight) of water was measured.
On the other hand, the pores of the fibrous activated carbon used for the adsorption of water in the measurement test of the saturated adsorption amount have a pressure of 1 atm (absolute pressure) specific to the sulfuric acid concentration of the sulfuric acid aqueous solution and an equilibrium water vapor pressure at 30 ° C. Kelv represented by the following equation 1 from the value (P)
It has a pore radius equal to or smaller than the pore radius (r) obtained based on the expression of in. That is, the cumulative pore volume of pores equal to or smaller than the pore radius determined based on the Kelvin's formula is the volume of water at 30 ° C. corresponding to the saturated adsorption amount in the measurement test. Similarly, using the same type of fibrous activated carbon, 13 types of sulfuric acid aqueous solutions having a change in sulfuric acid concentration (that is, having a specific gravity of 1.05 to 1.30 having a specific gravity of 0.025 spaced apart from each other). , A sulfuric acid aqueous solution having a specific gravity of 1.35, and a sulfuric acid aqueous solution having a specific gravity of 1.40). The cumulative pore volume was determined. By plotting the cumulative pore volume with respect to the pore radius based on the data of the cumulative pore volume obtained in this way, a pore distribution curve of the fibrous activated carbon can be obtained.

[0010]

Kelvin's equation : r = − [2Vm γ cos θ] / [RT ln (P / P ₀ )]

Wherein: r: pore radius (cm) Vm: molecular volume of water (cm ³ /mol)=18.079
(30 ° C.) γ: surface tension (dyne / cm) = 71.15 (30
° C) θ: Using the contact angle (°) between the capillary wall and water = 55 ° R: Gas constant (erg / deg · mol) = 8.314
3 × 10 ⁷ T: Absolute temperature (K) = 303.15 P: Saturated vapor pressure of water in pores (mmHg) P ₀ : 1 atm (absolute pressure) of water, saturated vapor pressure at 30 ° C.
(mmHg) = 31.824

From the values of V ₉ and V ₁₀₀ measured above, the ratio (%) of V _{9 to} V _100, which is the requirement (c) in the present invention, is calculated by the formula: (V ₉ / V ₁₀₀ ) × 100. Asked from.

The fibrous activated carbon used in the filler for a water purifier of the present invention has the above three requirements (a) to (c), that is, SA is 800 m ² / g or more and V ₉ is 0.20.
cc / g or more, and (V ₉ / V ₁₀₀ ) × 100 is 5
It is necessary to have all the characteristics of the three requirements of being 0% or more. By having these three requirements, it is possible for the first time to efficiently remove trihalomethanes, especially chloroform, in water, especially in tap water, even if they are only dissolved at low concentrations. Even if it lacks, trihalomethane in water cannot be removed efficiently. Among them, S
A is 1000 m ² / g or more, and V ₉ is 0.25 cc /
g or more, and (V ₉ / V ₁₀₀ ) × 100 is preferably 70% or more fibrous activated carbon.

If the SA is less than 800 m ² / g, even if the requirements (b) and (c) are satisfied, the ability to adsorb trihalomethane is reduced, making the material impractical as a filler for water purifiers. Further, when V ₉ is less than 0.20 cc / g, the trihalomethane adsorption ability is reduced even if the requirements (a) and (c) are satisfied.

In particular, for the fibrous activated carbon used in the filler for a water purifier of the present invention, the requirement of (c) that "(V ₉ / V ₁₀₀ ) × 100 is 50% or more" is important. If the ratio of the cumulative pore volume occupied by pores having a pore radius exceeding 9 ° is not larger than the cumulative pore volume occupied by pores having a pore radius of 9 ° or less, the ability to remove trihalomethane is not satisfied. It drops significantly.

Although the reason is not clear, the pore radius is 9
細孔 In the pores below, trihalomethane, which is a low molecular compound, is strongly adsorbed, whereas in pores with a pore radius of more than 9Å, even if trihalomethane is adsorbed, it is desorbed and contained in tap water. It is presumed that the trihalomethane formation reaction occurs between humic substances, which are precursors of trihalomethane, and chlorine used as a bleaching agent in the pores having a large diameter, or is replaced by a substance having a high adsorption capacity. You.

[0017] The fibrous activated carbon used for the filler for a water purifier of the present invention preferably has an average fiber diameter of 5 to 30 µm, particularly preferably 5 to 20 µm. When the average fiber diameter of the fibrous activated carbon is less than 5μ,
When used as a filler for water purifiers, the water flow resistance increases, making it difficult to purify water efficiently. On the other hand, if the average fiber diameter exceeds 30μ, the fibers themselves become brittle, and when filling the water purifier, When a molded body is produced by bonding or the like from activated carbon in the form of powder, it is easily broken and fine powder is easily generated. The length of the fibrous activated carbon is not particularly limited, and may be a short fiber or a long fiber.

The fibrous activated carbon for a filler for a water purifier of the present invention may be any fibrous activated carbon which satisfies all of the above three requirements (a) to (c). Raw materials, production conditions (eg, infusibilization conditions, carbonization conditions, activation conditions, etc.) used to produce the activated carbon in shape,
The manufacturing apparatus and the like are not particularly limited. As an example of a preferred production method, a raw material fiber such as a phenolic resin fiber is used for about 60
Under a high temperature of 0 to 1400 ° C., a condition for obtaining a fibrous activated carbon satisfying the above three requirements (a) to (c) is selected, and is treated with steam and / or carbon dioxide in a nitrogen stream. Or a method of activating with a combustion gas.

The fibrous activated carbon in the present invention can be filled in a water purifier in the form of fibers such as felt, cut fiber, filament, tow, and the like, and can be cylindrical, columnar, prismatic, plate-like. And the like, and can be filled into a water purifier. Therefore, the fibrous activated carbon for a filler for a water purifier referred to in the present invention includes the above (a) to (c)
And fibrous activated carbon which satisfies the requirements of the above with or without an adhesive.

From the viewpoint that the water purifier can be easily filled and a predetermined amount of the fibrous activated carbon can be filled in the water purifier, the fibrous activated carbon is predetermined in accordance with the internal shape and size of the water purifier. It is convenient to shape it into a shape.
In shaping, as long as the ability to remove trihalomethane does not decrease, an arbitrary method such as a method of shaping by lightly pressing as it is or a method of bonding and shaping fibers with an adhesive can be adopted.

In the case of shaping using an adhesive, various adhesives such as a fibrous or powdery thermoplastic resin and a polymer solution can be used. It is preferable to use a fibrous thermoplastic resin from the viewpoint of less blocking, and it is particularly preferable to use a core-in-sheath type composite fiber comprising a sheath component having a low melting point and a core component having a higher melting point. The amount of the adhesive used is not particularly limited, but usually,
It is preferable to use about 5 to 40% by weight based on the weight of the fibrous activated carbon.

Hereinafter, the present invention will be described specifically with reference to Examples and the like, but the present invention is not limited thereto. In the following examples, SA, V ₉ , V ₁₀₀ and (V ₉ / V ₁₀₀ ) × 100 were measured by the method described above.

Example 1 A phenolic resin fiber (a long fiber having an average fiber diameter of 14 μm) (manufactured by Nippon Kainol Co., Ltd .; Kainol KT2400) was introduced into a vertical slit furnace, and LPG combustion gas (propane / propane) at 980 ° C. was introduced. H obtained by burning a mixed gas having a volume ratio of air of about 1/24
While supplying ₂ O, CO ₂ , CO, H ₂ , a mixed gas of C ₃ H ₈ and N ₂ ) into the furnace, the mixture is treated under the condition of a residence time in the furnace of 10 minutes.
Average fiber diameter 10μ, SA = 1310 m ² / g, V ₁₀₀ =
0.532 cc / g, V ₉ = 0.465 cc / g, (V ₉
/ V ₁₀₀ ) × 100 = 87.4% of fibrous activated carbon. This fibrous activated carbon was cut to a length of 5 mm, and
0 g was filled in a cylindrical container for water purification having an inner diameter of 8 cm and a length of 8 cm.

<< Embodiment 2 >> The temperature of the LPG combustion gas is set to 1
The same treatment as in Example 1 was performed except that the temperature was set at 000 ° C. and the residence time in the furnace was set at 7 minutes.
1100 m ² / g, V ₁₀₀ = 0.273 cc / g, V ₉ =
0.250 cc / g, (V ₉ / V ₁₀₀ ) × 100 = 91.
6% of fibrous activated carbon was obtained. 5mm of this fibrous activated carbon
, And 60 g thereof were filled into a cylindrical container of the same type as in Example 1.

Example 3 A fibrous activated carbon obtained in the same manner as in Example 1 was cut into a length of 5 mm, and 100 parts by weight of the fibrous activated carbon was mixed with polyester fiber (single fiber denier) as an adhesive. = 1 denier, length 5mm) 2
0 parts by weight, and the paper was made with a tappy paper machine.
g / m ² were obtained. 130 ° C.
The sheet was pressed for 3 minutes under the condition of 8 kg / cm ² , and the sheet was placed between hot plates with controlled gaps and pressed at 260 ° C. for 2 minutes to produce a molded sheet having a density of 0.15 g / cc. The sheet was cut into a disc having a diameter of about 8 cm, and the disc was filled into a cylindrical container of the same type as that of Example 1 so that the filling amount was about 60 g.

<< Comparative Example 1 >> The temperature of the LPG combustion gas was 1
010 ° C., and the same treatment as in Example 1 except that the residence time in the furnace was 5 minutes.
1550 m ² / g, V ₁₀₀ = 0.430 cc / g, V ₉ =
0.210 cc / g, (V ₉ / V ₁₀₀ ) × 100 = 48.
8% of fibrous activated carbon was obtained. 5mm of this fibrous activated carbon
, And 60 g thereof were filled into a cylindrical container of the same type as in Example 1.

<< Comparative Examples 2-4 >> SA shown in Table 1 below
Value and has a V ₁₀₀ value and V ₉ values, activated carbon fiber (Comparative Example 2) to a commercially available phenol-based fibers as a raw material and the acrylic fiber fibrous activated carbon as a raw material (Comparative Example 3 4)
Was charged into a cylindrical container of the same type as in Example 1.

Comparative Example 5 The same commercially available fibrous activated carbon as used in Comparative Example 3 was cut into a length of about 5 mm.
Pressing was performed using an adhesive in the same manner as in Example 3 to produce a molded sheet having a density of 0.15 g / cc, which was cut into a disc having a diameter of about 8 cm, and the filling amount was about 6 cm.
It was filled in a cylindrical container of the same type as in Example 1 so that the amount became 0 g.

<< Trihalomethane removal test >> To a river water having a total organic carbon (TOC) concentration of 2.5 ppm, sodium hypochlorite was added at a ratio of a free chlorine concentration of 2 ppm.
Further, chloroform, bromoform, bromodichloromethane and dibromochloromethane were each dissolved at a concentration of 50 p.
Raw water for a water purification test was prepared in addition to pb, 20 ppb, 20 ppb and 20 ppb.

The raw water for a water purification test prepared as described above was added to each of the cylindrical containers containing the fibrous activated carbon prepared in Examples 1 to 3 and Comparative Examples 1 to 5 at a rate of 4 liters / min (SV6).
00hr ^-1 ), the trihalomethane in the treated water was analyzed every two hours by the headspace method according to JIS K0125, and the total amount of the above four types of trihalomethane and the amount of chloroform were graphed and removed. When the total water flow that could maintain the rate of 90% was examined, the results shown in Table 1 below were obtained.

[0031]

[Table 1] (V ₉ / V ₁₀₀ ) Total water amount maintained at 90% removal rate SA V ₉ V ₁₀₀ × 100 Trihalomethane Chloroform (m ² / g) (cc / g) (cc / g) (%) (liter) (liter) Example 1 1310 0.465 0.532 87.4 9700 12125 Example 2 1100 0.250 0.273 91.6 4800 5980 Comparative Example 1 1550 0.210 0.430 48.8 1920 2392 Comparative Example 2 1800 0.100 0.640 15.6 980 1250 Comparative Example 3 676 0.070 0.090 77.8 15 20 Comparative Example 4 720 0.150 0.150 100.0 18 25 Example 3----5820 7270 (Shape) Comparative Example 5----440 510 (Shape)

From the results in Table 1 above, it is found that Examples 1 and 2 in which SA, V ₉ and (V ₉ / V ₁₀₀ ) × 100 all satisfy the above requirements (a) to (c) of the present invention.
The shaped body of Example 3 produced from the fibrous activated carbon of Example 1 and the fibrous activated carbon of Example 1 has a high trihalomethane removing ability over a long period of time even when a large amount of water containing trihalomethane is passed, and particularly a high rate of chloroform. It can be seen that it can be removed with.

On the other hand, SA and V ₉ are within the range of the requirements (a) and (b) in the present invention, but (V ₉ /
Comparative Example 1 in which (V ₁₀₀ ) × 100 is less than 50% and deviates from requirement (c) of the present invention, SA is within the range of requirement (a) in the present invention, but V ₉ and (V ₉ / V ₁₀₀ )
Comparative Example 2 in which × 100 is out of the requirements (b) and (c) in the present invention, Comparative Example 3 and Comparative Example in which SA and V ₉ are out of the range of the requirements (a) and (b) in the present invention 4 and the shaped body of Comparative Example 5 produced from the fibrous activated carbon of Comparative Example 3 all have a reduced trihalomethane removing ability and chloroform removing ability with a very small amount of passage when water containing trihalomethane is passed. And
It turns out that it cannot be used as an effective trihalomethane removal material.

[0034]

The fibrous activated carbon of the present invention has an extremely high ability to remove trihalomethane contained in water, and in particular, it can efficiently remove chloroform, which accounts for the majority of trihalomethane in tap water, and is therefore extremely excellent as a filler for water purifiers. It can be effectively used for water purifiers used in various places such as homes, factories, stores, and companies. In the case of using fibrous activated carbon in the present invention, trihalomethane can be removed at a high rate even when the concentration of trihalomethane in tap water is as low as several tens of ppb. It does not cause a trihalomethane formation reaction on the activated carbon surface between the precursor humic substance and chlorine used as a disinfectant.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-99064 (JP, A) JP-A-6-23268 (JP, A) JP-A-63-283749 (JP, A) JP-A-62-1987 152533 (JP, A) JP-A-62-152534 (JP, A) JP-A-58-84180 (JP, A) JP-A-56-168824 (JP, A) JP-A-2-175607 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B01J 20/00-20/34 C01B 31/08 C02F 1/28

Claims (2)

(57) [Claims] (1) When a specific surface area is 800 m ² / g or more, and (b) a cumulative pore volume occupied by pores having a pore radius of 9 ° or less measured by a water vapor adsorption method is 0.20 cc / g or more. And (c) a pore radius of 9 ° measured by a water vapor adsorption method
A filler for a water purifier, wherein the filler has a cumulative pore volume occupied by the following pores of 50% or more of a cumulative pore volume occupied by pores having a pore radius of 100 ° or less. 2. The fibrous activated carbon has an average fiber diameter of 5 to 30 μm.
The filler for a water purifier according to claim 1, wherein the fibrous activated carbon is bonded with an adhesive.