JPH0699064A - Filler for water purifier - Google Patents

Abstract

PURPOSE:To obtain a filler for water purifier high in the removability of trihalomethane contained in water, capable of refreshing by hot water and effectively used for a long time 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 >=1300m<2>/g specific surface area, >=0.25cc/g cumulative pore volume occupied by a narrow pore having 9-16Angstrom pore radius measured by the steam adsorption method and >=50% ratio of the cumulative pore volume occupied by the narrow pore having 9-16Angstrom pore radius measured by the steam adsorption method to the cumulative pore volume occupied by a narrow pore having <=100 (1) pore radius. Thus, high removability of trihalomethane in water is attained, particularly chloroform occupying the most part of the trihalomethane in the water can be efficiently removed and the refreshing by hot water is capable and the removability of trihalomethane is not deteriorated even after repeating the process of purifying and refreshing.

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. More particularly, it relates to a filler for a water purifier that can efficiently remove trihalomethane in tap water and that can be easily regenerated by hot water when the ability to remove trihalomethane decreases.

[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 following drawbacks: (3) It has a low ability to remove chloroform, which accounts for most of the trihalomethanes contained in tap water.
At present, an effective activated carbon having a sufficient trihalomethane removing ability has not yet been developed.

Further, since water purifiers have been widely used in homes and various fields in recent years, the adsorbent to be filled in the water purifier can be easily used when trihalomethane or the like is adsorbed and its adsorbability is lowered. However, activated carbon which has high trihalomethane removal ability and is easily regenerated has not been known so far.

[0007]

From the above point of view, the present inventors intend to obtain an activated carbon which has a high trihalomethane removal ability without the drawbacks (1) to (3) described above and which can be easily regenerated. I have been researching for the purpose. 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 their distribution state are all significantly related to the trihalomethane removal ability and regeneration characteristics of activated carbon. It was found that in order to obtain activated carbon having removal ability and excellent reproducibility, the surface area of activated carbon, the diameter of pores in activated carbon, and the volume ratio and proportion of specific micropores should be specified. And completed the present invention.

That is, according to the present invention, (a) the specific surface area is 1
300 m ² / g or more, (b) the cumulative pore volume occupied by pores having a pore radius measured by the water vapor adsorption method of 9Å to 16Å is 0.25 cc / g or more, and (c) the water vapor adsorption method. Characterized in that it comprises fibrous activated carbon having a cumulative pore volume occupied by pores having a pore radius of 9Å to 16Å measured in step 50% or more of the cumulative pore volume occupied by pores having a pore radius of 100Å or less. It is a filling material for water purifiers.

[0009] Here, the "specific surface area" in the present invention (hereinafter referred to as "SA") (m ² / g), it refers to a value determined by the BET method by nitrogen gas adsorption isotherm at liquid nitrogen temperature. In addition, "the pore radius measured by the water vapor adsorption method is 9Å ~
"Cumulative pore volume occupied by 16 Å pores" (hereinafter referred to as " _V9-16 ") (cc / g) and "cumulative pore volume occupied by pores having a pore radius of 100 Å or less" (hereinafter hereafter) "V ₁₀₀ ") (cc / g) is defined based on the pore distribution curve created by the following method.

[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 were 1 atm (absolute pressure) peculiar to the sulfuric acid concentration of the aqueous sulfuric acid solution adopted, and the equilibrium water vapor pressure at 30 ° C. The pore radius of the pore is equal to or smaller than the pore radius (r) obtained from the value (P) based on the Kelvin's formula represented by the following mathematical formula 1. 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.

[0011]

## 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, V _{9 to 16} and V measured above
_From the value of ₁₀₀ , which is the above requirement (c) in the present invention,
The ratio (%) of V _{9 to 16 to} V _{100 is calculated} by the formula: (V _{9 to 16} /
V ₁₀₀ ) × 100.

The fibrous activated carbon used in the filler for a water purifier of the present invention has the three requirements (a) to (c) described above, that is, SA of 1300 m ² / g or more and V ₉ to ₁₆ of 0. 0.25 cc / g or more, and (V _{9 to 16} / V ₁₀₀ ).
It is necessary to have all the characteristics of three requirements that x100 is 50% or more. By having these three requirements, it is possible to remove trihalomethane in water, especially tap water for the first time, even if it is dissolved only at a low concentration, and it is very easy to regenerate with hot water. And lack of any of those requirements will not achieve the intended purpose. Among them, SA is 1500 m ² / g or more, and V _9-16
Is 0.40 cc / g or more, and (V _9-16 /
Fibrous activated carbon having V ₁₀₀ ) × 100 of 70% or more is preferable.

When the SA is less than 1300 m ² / g, even if the requirements of (b) and (c) are satisfied, the trihalomethane adsorption ability is lowered and it cannot be easily regenerated by hot water. When V ₉ to 16 is less than _0.25 cc / g, the trihalomethane removal ability and the regeneration performance are inferior even if the requirements of (a) and (c) are satisfied.

Particularly, in the fibrous activated carbon used in the filler for a water purifier of the present invention, "(V _{9 to 16} / V ₁₀₀ ) × 100"
Is more than 50% ”, the requirement of (c) is also important.
Not satisfying the requirement of (c), (V _{9 to 16} / V ₁₀₀ ) × 100 is 5
If it is less than 0%, the ability to remove trihalomethane is greatly reduced, or regeneration cannot be easily performed.

The inventors of the present invention have investigated the relationship between the pore size distribution and the trihalomethane absorption / desorption ability. As a result, although pores having a pore radius of less than 9Å have excellent trihalomethane adsorption ability, trihalomethane desorption by hot water is performed. It was found that the separation ability was poor, while the pores having a pore radius of more than 16 Å had a markedly poor trihalomethane adsorption ability.

Although the reason is not clear, the pore radius is 9
In the pores of Å or less, trihalomethane is strongly adsorbed and becomes difficult to be desorbed, while in the pores having a pore radius of more than 16Å, trihalomethane is difficult to adsorb, or trihalomethane of It is speculated that this is due to a trihalomethane-forming reaction between the precursor humic substance and chlorine used as a bleaching agent.

The fibrous activated carbon used in the water purifier filler of the present invention preferably has an average fiber diameter of 5 to 30 μm, and particularly preferably 5 to 20 μm. 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 directly filled in a water purifier in the form of fibers such as felt, cut fibers, filaments, tows, etc., and can be cylindrical, columnar, prismatic or plate-like. The water purifier can be filled with various shapes such as shapes. Therefore, the fibrous activated carbon for the water purifier filling material of the present invention is not shaped, and the fibrous activated carbon satisfying the requirements of the above (a) to (c), and with or without using an adhesive. Includes both shaped ones.

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 is predetermined in accordance with 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 fibrous activated carbon having reduced trihalomethane removal ability due to adsorption of trihalomethane is treated by supplying hot water to the fibrous activated carbon to desorb and regenerate the trihalomethane adsorbed on the fibrous activated carbon to obtain purified water. It can be reused as a filling material for vessels. The hot water temperature for regeneration is
The temperature is preferably 10 ° C. or more higher than the trihalomethane adsorption temperature of the fibrous activated carbon, and it is particularly preferable to use hot water of about 60 to 100 ° C.

The fibrous activated carbon can be regenerated by passing hot water through the water purifier with the fibrous activated carbon being filled in the water purifier, or by taking out the fibrous activated carbon from the water purifier and supplying hot water. Alternatively, it may be regenerated by washing in hot water. The amount of hot water used for one-time regeneration is appropriate according to the temperature of the hot water, the size and shape of the water purifier, the amount of fibrous activated carbon filled, the condition of use of the water purifier, the amount of trihalomethane accumulated in the packing material, etc. You can choose.

The fibrous activated carbon according to the present invention does not deteriorate in its ability to remove trihalomethanes not only once but also after being regenerated with hot water a number of times, so that purification water → regeneration → purification → regeneration ... By repeating water purification and regeneration, it can be effectively used for a very long time without being discarded as a water purifier filling material. Hereinafter, the present invention will be specifically described with reference to Examples and the like, but the present invention is not limited thereto. In the examples below, S
A, V _9-16 , V ₁₀₀ and (V _9-16 / V ₁₀₀ ) × 100 were measured by the method described above.

Example 1 Phenolic resin fibers (long fibers having an average fiber diameter of 14 μm) (manufactured by Nippon Kynol Co., Ltd .; Kynol KT2400) were introduced into a vertical slit furnace, and LPG combustion gas (propane / propane) of 1030 ° C. H ₂ obtained by burning a mixed gas with an air volume ratio of about 1/24
O, CO ₂ , CO, H ₂ , C ₃ H ₈ and N ₂ mixed gas) is fed into the furnace and treated under the condition that the residence time in the furnace is 12 minutes, and the average fiber diameter is 10 μm and SA = 2100 m. ² / g, V _9-16 =
0.57 cc / g, V ₁₀₀ = 0.75 cc / g, (V
_{9 to 16} / V ₁₀₀₎ to obtain a × 100 = 76.0% of the fibrous activated carbon. This fibrous activated carbon was cut into a length of 5 mm, and 60 g thereof 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 same phenolic resin fiber used in Example 1 was introduced into a vertical slit furnace of the same type as in Example 1, and a CO ₂ / N ₂ mixed gas (5
(0 volume / 50 volume) is supplied to the furnace while the residence time in the furnace is 7
The average fiber diameter is 10μ, SA = 190
_{^{0m 2 / g, V 9~16 =}} 0.50cc / g, V 100 = 0.
_{65 cc} / g, (V _9-16 / V ₁₀₀ ) × 100 = 76.9
% Fibrous activated carbon was obtained. This fibrous activated carbon was cut into a length of 5 mm, 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 fibrous activated carbon was used as a polyester fiber (single fiber denier) as an adhesive. = 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> Except that the temperature of the CO ₂ / N ₂ mixed gas was 950 ° C. and the residence time in the furnace was 30 minutes,
The same treatment as in Example 2 was performed to obtain an average fiber diameter of 10 μ and S
A = 900 m ² / g, V _9-16 = 0.02 cc / g, V
_{100 = 0.27cc / g, (V} 9~16 / V 100) × 100
= 7.4% of fibrous activated carbon was obtained. This fibrous activated carbon was cut into a length of 5 mm, 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.
Of commercially available fibrous activated carbon having phenol value, V ₁₀₀ value and V ₉ to ₁₆ value (comparative example 2) and acrylic fiber as a raw material (comparative examples 3 and 4) Each 60 g was filled into a cylindrical container of the same type as in Example 1.

Comparative Example 5 The fibrous activated carbon obtained in Comparative Example 1 was cut into a length of about 5 mm, and then pressed with an adhesive in the same manner as in Example 3 to obtain a density of 0.1.
A molded sheet of 5 g / cc is prepared, and this has a diameter of about 8 cm.
It was cut into a disk shape and filled in a cylindrical container of the same type as in Example 1 so that the filling amount was about 60 g.

Examples 1 and 2 and Comparative Examples 1 to 1
The SA value, V _9-16 value, V ₁₀₀ value and (V _9-16 / V ₁₀₀ ) × 100 value of the fibrous activated carbon in _No. 4 are summarized as _follows .
It is as shown in Table 1 below.

[0034]

[Table 1] (V _9-16 / V ₁₀₀ ) SA V _9-16 V ₁₀₀ × 100 (m ² / g) (cc / g) (cc / g) (%) Example 1 2100 0.57 0.75 76.0 Example 2 1900 0.50 0.65 76.9 Comparative Example 1 900 0.02 0.27 7.4 Comparative Example 2 1480 0.19 0.42 45.2 Comparative Example 3 1340 0.21 0.40 52.5 Comparative Example 4 675 0.02 0.09 22.2

<< Trihalomethane Removal Test and Regeneration 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, and chloroform, bromoform and bromodichloromethane were further added. And dibromochloromethane were added so that the respective concentrations were 50 ppb, 20 ppb, 20 ppb and 20 ppb to prepare raw water for the water purification test.

4 liters / minute (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.
00 hr ^-1 ) for 2 hours to pass JIS K01
The amount of chloroform in the treated water and the total amount of the above four trihalomethanes were analyzed by the headspace method according to 25.

Once the water flow is stopped, hot water at 92 ° C. is
After passing through each water purifier for 3 minutes at a flow rate of 1 liter / minute for regeneration, the mixture was again passed at a flow rate of 4 liters / minute (SV600 hr ⁻¹ ) for 2 hours, and treated in the water after treatment by the above headspace method. The amount of chloroform and the total amount of the above four trihalomethanes were analyzed. When this liquid passing / regeneration operation was repeated 5 times in total, the results of analysis of the amount of chloroform and the total amount of the above-mentioned 4 types of trihalomethanes were as follows.
The results are shown in Table 2 below.

[0038]

[Table 2]  Concentration in treated water (ppb) after passing 2 hours Chloroform Total trihalomethane Views 0 1 2 3 4 5 0 1 2 3 4 5  Same as left Same as left Same as left Same as left Same as left Same as left 8 or less Same as left Same left Same left Same left same left Same as left Example 2 2 and below Same left Same left Same left Same left same 5 8 Below 75 Comparative Example 2 2 or less 7 10 18 22 35 8 or less 12 18 32 42 60 Comparative Example 3 51 53 52 − − − 92 95 94 − − − Comparative Example 4 53 55 58 − − − 95 99 105 − − − Example 3 2 or less Same as left Same as left Same as left 5 6 2 or less Same as left Same left Same as left 9 11 Comparative example 5 2 or less Same as left 16 51 58 − 2 or less Same as left 29 92 105 −

From the results shown in Table 2 above, all of SA, V _{9 to 16} and (V _{9 to 16} / V ₁₀₀ ) × 100 satisfy the requirements (a) to (c) in the present invention. The shaped article of Example 3 made from the fibrous activated carbons of Examples 1 and 2 and the fibrous activated carbon of Example 1 efficiently removes chloroform and various other trihalomethanes when a large amount of water containing trihalomethanes is passed through. It can be removed, and its trihalomethane removing ability does not change at all even after being regenerated 5 times, or slightly decreases, and it can be seen that it can be effectively used as a trihalomethane removing material for a long period of time by repeating purification / regeneration.

On the contrary, the requirements (a) to
The fibrous activated carbons of Comparative Examples 1 to 5, which lack even one of (c), have low trihalomethane removal ability from the beginning, or have trihalomethane removal ability at the beginning even though they have trihalomethane removal ability. It can be seen that it cannot be effectively used from the beginning or cannot be regenerated and used without recovery.

[0041]

Industrial Applicability The fibrous activated carbon of the present invention has an extremely high ability to remove trihalomethane contained in water, and in particular, can effectively remove chloroform, which accounts for the majority of trihalomethane, 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 addition, the fibrous activated carbon of the present invention can be regenerated by hot water, its trihalomethane removal ability is hardly deteriorated even after repeating the steps of water purification / regeneration a number of times, and filling for a water purifier for an extremely long period of time. It can be used effectively without being discarded as a material. Moreover, since it can be regenerated with hot water, it does not require a large-scale regenerating facility, and even a home or the like that does not have a normal regenerating facility can simply regenerate it by passing hot water. .

Claims (2)

[Claims] 1. A specific surface area of 1300 m ² / g or more, and a pore radius of 9Å to 1 as measured by a water vapor adsorption method.
The cumulative pore volume occupied by 6Å pores is 0.25 cc / g or more, and (c) the cumulative pore volume occupied by pores having a pore radius measured by the water vapor adsorption method of 9Å to 16Å is Is a fibrous activated carbon which is 50% or more of the cumulative pore volume occupied by pores 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.