JPH0699065A - Filler for water purifier - Google Patents

Abstract

PURPOSE:To obtain a filler high in the removability of trihalomethane particularly chloroform contained in water, capable of being effectively used for a domestic water purifier or the like by using a fibrous active carbon having a specified specific surface area, a specified cumulative pore volume and specified cumulative pore volume ratio. CONSTITUTION:This filler is composed of the fibrous active carbon having >=800m<2>/g specific surface area, >=0.20cc/g cumulative pore volume occupied by a narrow pore having <=9Angstrom pore radius message by the steam adsorption method and >=50% ratio of the cumulative pore volume occupied by the narrow pore having >=9Angstrom pore radius measured by the steam adsorption method to the cumulative pore volume occupied by a narrow pore having <=100Angstrom pore radius. And av. fiber diameter of the fibrous active carbon is 5-30mum and the fibrous active carbon is stuck to each other by an adhesive. Thus, high removability of trihalomethane particularly chloroform in water is attained and is exhibited even when the conc. of trihalomethane in water is several tens ppb.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Although a slight amount of trihalomethane is dissolved in tap water, it has been suspected that trihalomethane itself is a carcinogen, so that in recent years, with increasing concern about health, The presence of trihalomethane is highlighted. Trihalomethane is a general term for organic compounds in which 3 hydrogen atoms out of 4 hydrogen atoms of methane are replaced by halogen, and chloroform, bromoform, bromodichloromethane, dibromochloromethane, etc. are contained in it, and tap water Chloroform comprises about 40-50% of the trihalomethanes contained.

It is known that this trihalomethane is produced by the reaction of humic substances contained in tap water raw water with chlorine used for the purpose of sterilization, and the process of sterilizing tap water with a chlorine-based bactericide is known. In the current situation, which is indispensable, it is extremely difficult to prevent the occurrence. Therefore, the removal of trihalomethane generated in tap water has become an important issue.

Conventionally, it has been proposed to use various types of activated carbon such as granular, powdery and fibrous substances for the purpose of removing trihalomethane from water. And, JP-A-62-15
As described in Japanese Patent No. 2533, among these activated carbons, fibrous activated carbon is said to have high trihalomethane removal ability.

However, the conventional activated carbon including the above-mentioned fibrous activated carbon is (1) the concentration of trihalomethane contained in tap water is usually as low as several tens of ppb, which is very low. (2) The humic substance, which is a precursor of trihalomethane contained in tap water, and chlorine used as a bactericide, react on the surface of the activated carbon to rather generate trihalomethane. It has the drawbacks that it may promote (3) the ability to remove chloroform, which accounts for most of the trihalomethanes contained in tap water, is low, and an effective activated carbon that has sufficient ability to remove trihalomethanes The current situation is that it has not been developed yet.

[0006]

From the above point of view, the present inventors have conducted research for the purpose of obtaining an activated carbon having a high trihalomethane removal ability without the above-mentioned drawbacks (1) to (3). . As a result, in addition to the surface area of activated carbon, the diameter of pores in activated carbon, and the volume ratio of specific fine pores and its distribution state are all significantly involved in the trihalomethane removal ability of activated carbon, and the above-mentioned conventional techniques. In order to obtain an activated carbon with high trihalomethane removal ability without the drawbacks described in 1., it is advisable to make the surface area of the activated carbon, the diameter of the pores in the activated carbon, and the volume ratio and ratio of specific micropores specific. Then, the present invention was completed.

That is, according to the present invention, (a) the specific surface area is 8
The cumulative pore volume occupied by pores having a pore radius of 9 Å or less measured by the water vapor adsorption method (b) is not more than 0. 00 m ² / g.
A cumulative pore volume of 20 cc / g or more and (c) pores having a pore radius of 9 Å or less measured by a water vapor adsorption method is 50, which is a cumulative pore volume of pores having a pore radius of 100 Å or less.
% Of the fibrous activated carbon is a filler for a water purifier.

Here, the "specific surface area" (hereinafter referred to as "SA") (m ² / g) in the present invention means a value obtained by the BET method by the nitrogen gas adsorption isotherm at the liquid nitrogen temperature. Also, "cumulative pore volume occupied by pores having a pore radius of 9 Å or less measured by a water vapor adsorption method" (hereinafter referred to as "V ₉ ")
(Cc / g) and measured by the same method Sita "pore radius 100Å
The following cumulative pore volume occupied by pores "(hereinafter referred to as" V ₁₀₀ ") (cc / g) is defined based on a pore distribution curve was prepared as follows.

[Method of creating pore distribution curve] Since the equilibrium water vapor pressure of a sulfuric acid aqueous solution having a constant concentration has a constant value, there is a uniform relationship between the sulfuric acid concentration of the sulfuric acid aqueous solution and the equilibrium water vapor pressure. Fibrous activated carbon was placed in the vapor phase part of the adsorption chamber in which a sulfuric acid aqueous solution having a predetermined concentration was present, and contacted with water vapor under the conditions 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 are 1 atm (absolute pressure) peculiar to the sulfuric acid concentration of the adopted sulfuric acid aqueous solution, and the equilibrium water vapor pressure at 30 ° C. Kelv expressed by the following formula 1 from the value (P)
It has a pore radius equal to or smaller than the pore radius (r) obtained based on the formula of in. That is, the cumulative pore volume of pores having a pore radius or less, which is obtained based on the Kelvin equation, is the volume of water at 30 ° C. corresponding to the saturated adsorption amount in the measurement test. Similarly, using the same kind of fibrous activated carbon, 13 kinds of sulfuric acid aqueous solutions having different sulfuric acid concentrations (that is, having a specific gravity of 1.05 to 1.30 at intervals of 0.025 11 Seed sulfuric acid aqueous solution, sulfuric acid aqueous solution having a specific gravity of 1.35, and sulfuric acid aqueous solution having a specific gravity of 1.40), a saturated adsorption amount measurement test was performed, and in each measurement test, The cumulative pore volume was determined. The pore distribution curve of the fibrous activated carbon can be obtained by plotting the cumulative pore volume against the pore radius based on the data of the cumulative pore volume thus obtained.

[0010]

## EQU1 ## Kelvin's formula : r =-[2Vm γ cos θ] / [RT ln (P / P ₀ )]

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

Then, 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 I asked from.

The fibrous activated carbon used in the filler for a water purifier of the present invention has three requirements (a) to (c) described above, 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 0% or more. By providing these three requirements, trihalomethane in water, especially tap water, especially chloroform, can be efficiently removed even if it is dissolved only at a low concentration. 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 /
A fibrous activated carbon having a g or more and a (V ₉ / V ₁₀₀ ) × 100 of 70% or more is preferable.

If the SA is less than 800 m ² / g, even if the requirements of (b) and (c) are satisfied, the trihalomethane adsorption capacity is lowered and it becomes unpractical as a filler for water purifiers. Further, when V ₉ is less than 0.20 cc / g, the trihalomethane adsorption ability is lowered even if the requirements (a) and (c) are satisfied.

Particularly, in the fibrous activated carbon used in the filler for water purifiers of the present invention, the requirement of (c) that "(V ₉ / V ₁₀₀ ) × 100 is 50% or more" is important, and this (c) When the ratio of the cumulative pore volume occupied by pores having a pore radius exceeding 9Å is not larger than the cumulative pore volume occupied by pores having a pore radius of 9Å or less, the trihalomethane removal ability is Drastically reduced.

Although the reason is not clear, the pore radius is 9
Trihalomethane, which is a low molecular weight compound, is strongly adsorbed in the pores of Å or less, while it is desorbed and contained in tap water even when trihalomethane is adsorbed in the pores with a radius of more than 9Å. It is presumed that this is due to the substitution of a substance having a high adsorption capacity for the humic substance, or the occurrence of a trihalomethane formation reaction between the humic substance, which is a precursor of trihalomethane, and chlorine used as a bleaching agent in the pores of large diameter. It

The fibrous activated carbon used in the filler for water purifiers of the present invention preferably has an average fiber diameter of 5 to 30 µ, and particularly preferably 5 to 20 µ. When the average fiber diameter of the fibrous activated carbon is less than 5 μ,
When used as a filler for water purifiers, water resistance increases, making it difficult to efficiently purify water. On the other hand, when the average fiber diameter exceeds 30μ, the fibers themselves become brittle, and when filling water purifiers or When the molded body is manufactured from the granular activated carbon by adhesion or the like, it tends to be crushed to generate fine powder. The length of the fibrous activated carbon is not particularly limited, and may be short fiber or long fiber.

The fibrous activated carbon for the water purifier filling material of the present invention may be any fibrous activated carbon satisfying all of the above three requirements (a) to (c). Raw materials used for producing the activated carbon powder, production conditions (for example, infusibilization conditions, carbonization conditions, activation conditions, etc.),
The manufacturing device and the like are not particularly limited. As an example of a preferable manufacturing method, a raw material fiber such as a phenolic resin fiber is prepared by about 60
Whether to treat with steam and / or carbon dioxide gas in a nitrogen stream by selecting conditions under which a fibrous activated carbon having the above three requirements (a) to (c) can be obtained at a high temperature of 0 to 1400 ° C. Alternatively, a method of activation treatment with combustion gas can be used.

The fibrous activated carbon in the present invention can be filled in a water purifier in a fiber form such as a felt form, a cut fiber form, a filament form, and a tow form, and is also cylindrical, columnar, prismatic or plate-like. And the like, and the fibrous activated carbon for a water purifier filling material according to the present invention has the above-mentioned (a) to (c).
Also included are fibrous activated carbons satisfying the requirement of 1) which are shaped with or without an adhesive.

From the standpoint that the water purifier can be easily filled and a predetermined amount of fibrous activated carbon can be filled in the water purifier, the fibrous activated carbon can be preliminarily specified according to the internal shape and size of the water purifier. It is convenient to shape the shape.
As for shaping, as long as the ability to remove trihalomethane is not deteriorated, any method such as a method of directly pressing with light pressure, a method of joining fibers with an adhesive and shaping, or the like can be adopted.

When an adhesive is used for shaping, various adhesives such as fibrous or powdery thermoplastic resins and polymer solutions can be used. It is preferable to use a fibrous thermoplastic resin from the viewpoint of less clogging, and it is particularly preferable to use a core-sheath type composite fiber composed of 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.

The present invention will be specifically described below 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 Phenolic resin fibers (long fibers having an average fiber diameter of 14 μ) (manufactured by Nippon Kynol Co., Ltd .; Kynol KT2400) were introduced into a vertical slit furnace, and LPG combustion gas (propane / propane / 980 ° C.) was introduced. H obtained by burning a mixed gas with an air volume ratio of about 1/24
₂ O, CO ₂ , CO, H ₂ , C ₃ H ₈ and N ₂ mixed gas) is supplied into the furnace, and the treatment is performed under the condition that the residence time in the furnace is 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% fibrous activated carbon was obtained. This fibrous activated carbon was cut into a length of 5 mm, and 6
0 g was filled in a cylindrical container for water purification having an inner diameter of 8 cm and a length of 8 cm.

Example 2 The temperature of the LPG combustion gas was set to 1
The same treatment as in Example 1 was performed except that the temperature was set to 000 ° C. and the residence time in the furnace was set to 7 minutes, and the average fiber diameter was 10 μ and SA =
1100 m ² / g, V ₁₀₀ = 0.273 cc / g, V ₉ =
0.250 cc / g, (V ₉ / V ₁₀₀ ) × 100 = 91.
6% fibrous activated carbon was obtained. 5 mm of this fibrous activated carbon
Was cut to a length of 60 g, and 60 g thereof was filled in a cylindrical container of the same type as in Example 1.

Example 3 The fibrous activated carbon obtained in the same manner as in Example 1 was cut into a length of 5 mm, and then 100 parts by weight of the activated fibrous carbon was used as an adhesive for polyester fibers (single fiber denier). = 1 denier, length 5mm) 2
Add 0 parts by weight and make a paper with a tappy paper machine.
A sheet of g / m ² was obtained. The obtained sheet at 130 ° C.
The sheet was pressed under a condition of 8 kg / cm ² for 3 minutes, and then this sheet was put between hot plates with controlled gaps and pressed at 260 ° C. for 2 minutes to prepare a molded sheet having a density of 0.15 g / cc. This sheet was cut into a disk shape having a diameter of about 8 cm, and filled in 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 set to 1
The treatment was performed in the same manner as in Example 1 except that the temperature was set to 010 ° C. and the residence time in the furnace was set to 5 minutes, and the average fiber diameter was 10 μm and SA =
1550 m ² / g, V ₁₀₀ = 0.430 cc / g, V ₉ =
0.210 cc / g, (V ₉ / V ₁₀₀ ) × 100 = 48.
8% fibrous activated carbon was obtained. 5 mm of this fibrous activated carbon
Was cut to a length of 60 g, and 60 g thereof was filled in a cylindrical container of the same type as in Example 1.

Comparative Examples 2 to 4 SA shown in Table 1 below
Fibrous activated carbon made of commercially available phenolic fiber as raw material (Comparative Example 2) and fibrous activated carbon made of acrylic fiber as raw material (Comparative Examples 3 and 4) having values of ₁₀₀ , V ₁₀₀ and V ₉
60 g of each of the above 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 that used in Comparative Example 3 was cut into a length of about 5 mm,
A molded sheet having a density of 0.15 g / cc was prepared by pressing with an adhesive in the same manner as in Example 3, cut into a disk having a diameter of about 8 cm, and the filling amount was about 6
A cylindrical container of the same type as that of Example 1 was filled so that the amount became 0 g.

<< Trihalomethane Removal Test >> Sodium hypochlorite was added to river water having a total organic carbon (TOC) concentration of 2.5 ppm at a ratio of a free chlorine concentration of 2 ppm,
Chloroform, bromoform, bromodichloromethane and dibromochloromethane were added at a concentration of 50 p
Raw water for the water purification test was prepared by adding pb, 20 ppb, 20 ppb and 20 ppb.

4 liter / min (SV6) of the raw water for water purification test prepared 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 described above.
Flow rate of 00 hr ⁻¹ ), and the trihalomethane in the water after the treatment was analyzed every 2 hours by the headspace method according to JIS K0125, and the total amount of the above-mentioned 4 types of trihalomethanes and the amount of chloroform were graphed to remove them. When the total water flow rate capable of maintaining the rate of 90% was investigated, the results shown in Table 1 below were obtained.

[0031]

[Table 1] (V ₉ / V ₁₀₀ ) Removal rate 90% Maintenance total water amount 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 (shaped object) Comparative Example 5 − − − − 440 510 (shaped object)

From the results of Table 1 above, Examples 1 and 2 in which all of SA, V ₉ and (V ₉ / V ₁₀₀ ) × 100 satisfy the above-mentioned requirements (a) to (c) in the present invention.
The shaped body of Example 3 prepared from the fibrous activated carbon of Example 1 and the fibrous activated carbon of Example 1 has a high trihalomethane removal ability for a long period of time even when a large amount of water containing trihalomethane is passed through, and particularly, the chloroform has a high rate of removal. You can see 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 /
V ₁₀₀ ) × 100 is less than 50% and is out of the requirement (c) of the present invention, Comparative Example 1 and SA are in the range of the requirement (a) in the present invention, but V ₉ and (V ₉ / V ₁₀₀ )
Comparative Example 2 in which x100 is outside the requirements (b) and (c) of the present invention, and Comparative Examples 3 and Comparative Examples in which SA and V ₉ are out of the ranges of requirements (a) and (b) in the present invention. 4 and the shaped bodies of Comparative Example 5 produced from the fibrous activated carbon of Comparative Example 3 all had a very small amount of passage of water containing trihalomethane, and the ability to remove trihalomethane and the ability to remove chloroform decreased. And
It can be seen that it cannot be used as an effective trihalomethane removal material.

[0034]

INDUSTRIAL APPLICABILITY The fibrous activated carbon according to the present invention has an extremely high ability to remove trihalomethane contained in water, and in particular, 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. When the fibrous activated carbon in the present invention is used, the trihalomethane can be removed at a high rate even when the concentration of trihalomethane in the tap water is extremely low, such as several tens of ppb. It does not cause a trihalomethane formation reaction on the surface of activated carbon between the precursor humic substance and chlorine used as a bactericide.

Claims (2)

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