JP3122205B2 - 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. More specifically, the present invention relates to a filler for a water purifier that can efficiently remove trihalomethane from tap water and that can be easily regenerated with hot water when the ability to remove trihalomethane is reduced.

[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 disadvantages that it may promote, (3) the ability to remove chloroform, which accounts for most of the trihalomethanes contained in tap water, is low,
At present, an effective activated carbon having sufficient trihalomethane removal 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 therein can be easily used when trihalomethane or the like is adsorbed and its adsorbing ability is reduced. It has been demanded that the activated carbon has a high trihalomethane removal ability and can be easily regenerated.

[0007]

SUMMARY OF THE INVENTION In view of the above, the present inventors have made it possible to obtain an activated carbon which does not have the above-mentioned disadvantages (1) to (3), has a high trihalomethane removing ability, and can be easily regenerated. I have been conducting research for the purpose. 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 significantly involved in the trihalomethane removal ability and regeneration characteristics of the activated carbon, and trihalomethane In order to obtain activated carbon with removal ability and excellent regenerative properties, it was found that 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. Thus, the present invention has been completed.

That is, according to the present invention, (a) the specific surface area is 1
300m and ² / g or more, (b) the cumulative pore volume pore radius as measured by water vapor adsorption method occupied by pores 9Å~16Å is not less 0.25 cc / g or more, and (c) a water vapor adsorption method Characterized in that the cumulative pore volume occupied by pores having a pore radius of 9 to 16 ° measured by the above is 50% or more of the cumulative pore volume occupied by pores having a pore radius of 100 ° or less. It is a filler for water purifiers.

Here, 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, “the pore radius measured by the water vapor adsorption method is 9Å-
"Cumulative pore volume occupied by 16 _mm pores" (hereinafter referred to as " _V9-16 ") (cc / g) and "cumulative pore volume occupied by pores having a pore radius of 100 _{mm or less} " (hereinafter referred to as " _V9-16 ") (cc / g). (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 a sulfuric acid aqueous 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. It has a pore radius equal to or smaller than the pore radius (r) obtained from the value (P) based on Kelvin's formula represented by the following equation 1. 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.

[0011]

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

Where: 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

Then, V _9-16 and V
_From the value of ₁₀₀ , the above requirement (c) in the present invention,
The ratio (%) of V _{9-16 to} V _{100 is calculated} by the formula: (V _9-16 /
V ₁₀₀ ) × 100.

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 1300 m ² / g or more, and V ₉ to ₁₆ is 0. is a .25cc / g or more, and _(V 9~16 / V ₁₀₀₎
It is necessary to have all the characteristics of the three requirements that x100 is 50% or more. Having these three requirements, for the first time, efficiently remove trihalomethanes, especially chloroform, in water, especially tap water, even if only dissolved at low concentrations, and regenerate them very easily with hot water. And lack of any of these 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 /
Activated carbon fiber V ₁₀₀₎ × 100 is 70% or more is preferable.

If the SA is less than 1300 m ² / g, even if the requirements (b) and (c) are satisfied, the ability to adsorb trihalomethane is reduced, and it cannot be easily regenerated by hot water. When V _9-16 is less than _0.25 cc / g, the trihalomethane removing ability and the regenerating performance are still 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 _9-16 / V ₁₀₀ ) × 100"
Is more than 50% ”is also important.
The condition of (c) was not satisfied, and (V _9-16 / V ₁₀₀ ) × 100 was 5
If it is less than 0%, the ability to remove trihalomethane is greatly reduced, or it cannot be easily regenerated.

The present inventors have studied the relationship between the pore diameter distribution and the ability to absorb and desorb trihalomethane. As a result, pores having a pore radius of less than 9 ° have excellent trihalomethane adsorption ability, but desorption of trihalomethane by hot water. It was found that the separation ability was inferior, while the pores having a pore radius of more than 16 ° had remarkably inferior trihalomethane adsorption ability.

Although the reason is not clear, the pore radius is 9
In the pores of Å or less, the trihalomethane is strongly adsorbed and hardly desorbed, while in the pores having a pore radius of more than 16Å, it is difficult to adsorb the trihalomethane or in the pores having a large diameter, It is presumed that the reaction is caused by a trihalomethane formation reaction between the precursor humic substance and chlorine used as the bleaching agent.

The fibrous activated carbon used in the filler for a water purifier of the present invention preferably has an average fiber diameter of 5 to 30 μm, and particularly preferably has an average fiber diameter of 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 into a water purifier as it is in the form of fibers such as felt, cut fiber, filament and tow. It can be shaped into various shapes such as a shape and filled into a water purifier. Therefore, the fibrous activated carbon for a filler for a water purifier according to the present invention is a fibrous activated carbon that satisfies the above-mentioned requirements (a) to (c), and uses or does not use an adhesive. Includes both shaped forms.

From the viewpoint that the water purifier can be easily filled and a predetermined amount of the fibrous activated carbon can be filled into 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.

The fibrous activated carbon having reduced trihalomethane removing ability due to adsorption of trihalomethane is purified by supplying hot water to the fibrous activated carbon to desorb and regenerate the trihalomethane adsorbed on the fibrous activated carbon. It can be reused as dexterity filler. The hot water temperature for regeneration is
The temperature is preferably at least 10 ° C. 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 regeneration of the fibrous activated carbon can be carried out by passing hot water through the water purifier while the fibrous activated carbon is filled in the water purifier, or by removing the fibrous activated carbon from the water purifier and supplying hot water. Alternatively, regeneration may be performed by washing in hot water. The amount of hot water used for one regeneration is appropriately determined according to the temperature of the hot water, the size and shape of the water purifier, the filling amount of the fibrous activated carbon, the usage state of the water purifier, the accumulation amount of trihalomethane in the filling material, and the like. You can choose.

In the fibrous activated carbon of the present invention, the trihalomethane removal ability does not decrease even after the regeneration with hot water is repeated not only once but also many times. By repeatedly purifying and regenerating water, it can be effectively used without being disposed of as a filler for a water purifier for an extremely long time. 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 example, S
A, V _9-16 , V ₁₀₀ and (V _9-16 / V ₁₀₀ ) × 100 were measured by the methods 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 1030 ° C. was introduced. H ₂ obtained by burning a mixed gas having a volume ratio of air of about 1/24
O, CO ₂ , CO, H ₂ , C ₃ H ₈ and a mixed gas of N ₂ ) were supplied into the furnace and treated under the conditions of a residence time of 12 minutes in the furnace, and an average fiber diameter of 10 μm and SA = 2100 m ² / g, _V9-16 =
0.57 cc / g, V ₁₀₀ = 0.75 cc / g, (V
_9-16 / V ₁₀₀ ) × 100 = 76.0% of fibrous activated carbon was obtained. This fibrous activated carbon was cut into a length of 5 mm, and 60 g of the cut carbon was filled into 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 as 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) into the furnace while the residence time in the furnace is 7
Min, the average fiber diameter is 10 μ, SA = 190
0 m ² / g, V _9-16 = 0.50 cc / g, V ₁₀₀ = 0.
_{65cc / g, (V 9~16 /} V 100) × 100 = 76.9
% Of fibrous activated carbon was obtained. This fibrous activated carbon was cut to a length of 5 mm, and 60 g of the cut carbon was filled in 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 a 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 A CO ₂ / N ₂ mixed gas was set at a temperature of 950 ° C. and a residence time in a furnace was set at 30 minutes.
The same treatment as in Example 2 was performed to obtain an average fiber diameter of 10 μm,
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 to a length of 5 mm, and 60 g of the cut carbon 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
Value and has a V ₁₀₀ value and V _{9 to 16} values, commercial phenolic fiber fibrous activated carbon as a raw material (Comparative Example 2) and acrylic fibers fibrous activated carbon 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 pressed using an adhesive in the same manner as in Example 3 to obtain a density of 0.1%.
A molded sheet of 5 g / cc was produced, and this was approximately 8 cm in diameter.
And cut into a disc shape, and filled into a cylindrical container of the same type as in Example 1 so that the filling amount was about 60 g.

The above Examples 1, 2 and Comparative Examples 1 to
The SA value, V _9-16 value, V ₁₀₀ value and (V _9-16 / V ₁₀₀ ) × 100 values 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 at concentrations of 50 ppb, 20 ppb, 20 ppb and 20 ppb to prepare raw water for a water purification test.

The raw water for a water purification test prepared as described above was placed in each of the cylindrical containers containing fibrous activated carbon prepared in Examples 1 to 3 and Comparative Examples 1 to 5 at a rate of 4 liters / min (SV6).
00 hr ^-1 ) for 2 hours.
The amount of chloroform in the treated water and the total amount of the above four types of trihalomethanes were analyzed by the headspace method according to No. 25.

Once the water flow was stopped, hot water at 92 ° C.
After regenerating by passing through each water purifier at a flow rate of 3 liter / min for 3 minutes, the solution was passed again at a flow rate of 4 liter / min (SV 600 hr ^-1 ) for 2 hours, and the water in the treated water was treated by the above headspace method. The amount of chloroform and the total amount of the above four kinds of trihalomethanes were analyzed. When this flow-through / regeneration operation was repeated a total of five times, the results of analysis of the amount of chloroform and the total amount of the above four types of trihalomethanes were as follows:
The results are shown in Table 2 below.

[0038]

[Table 2]  Concentration in treated water after passing water for 2 hours (ppb) Chloroform Trihalomethane total Views 0 1 2 3 4 5 0 1 2 3 4 5  Example 1 2 and below Same as left Same as left Same as left Same as left 8 and below Same as left Same as left Same as left Same as left Same as left 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 5 6 2 or less Same as 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 in Table 2 above, it is found that SA, V _{9 to 16} and (V _{9 to 16} / V ₁₀₀ ) × 100 all satisfy the requirements (a) to (c) of the present invention. The shaped body of Example 3 prepared from the fibrous activated carbon of Examples 1 and 2 and the fibrous activated carbon of Example 1 efficiently converts chloroform and various other trihalomethanes when passing a large amount of water containing trihalomethane. The trihalomethane-removing ability can be removed, and the trihalomethane-removing ability does not change at all or is reduced only slightly after regeneration five times. It can be seen that by repeating purification / regeneration, the trihalomethane can be effectively used as a trihalomethane removing material for a long time.

On the other hand, the requirements (a) to
The fibrous activated carbons of Comparative Examples 1 to 5 lacking even one of (c) have low trihalomethane removing ability from the beginning, or even if they have trihalomethane removing ability at first, the trihalomethane removing ability by regeneration is reduced. It does not recover, indicating that it cannot be used effectively from the beginning or that it cannot be reproduced and used.

[0041]

The fibrous activated carbon of 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, 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 with hot water, its trihalomethane removing ability hardly decreases even after repeating the water purification / regeneration process many times, and the filling for the water purifier can be performed for an extremely long time. It can be used effectively without being discarded as material. In addition, since regeneration can be performed using hot water, a large-scale regeneration facility is not required, and even homes without ordinary regeneration facilities can simply perform regeneration by simply passing hot water through. .

Continuation of the front page (56) References JP-A-6-99065 (JP, A) JP-A-6-23268 (JP, A) JP-A-63-283749 (JP, A) JP-A-62-152533 (JP) 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) The specific surface area is 1300 m ² / g or more, and (b) the pore radius measured by a water vapor adsorption method is 9Å to 1
The cumulative pore volume occupied by 6% of the pores is 0.25 cc / g or more, and (c) the cumulative pore volume occupied by the pores having a pore radius of 9 ° to 16 ° measured by the water vapor adsorption method is the pore radius. Of fibrous activated carbon having a pore size of 50% or more of the cumulative pore volume occupied by pores 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.