JPH0819717A - Sheet type filter medium for water purification - Google Patents

Abstract

PURPOSE:To obtain a sheet type filter medium for water purification having a good water purification capacity in which active carbon is prevented from falling off and pressure loss during the passage of water is kept low. CONSTITUTION:A sheet type filter medium for water purification contains 100 pts.wt. of active carbon powder with particle size 10-150mum, pare diameter 30-300 angstrom, pore volume 0.15cc/g or more, 10-200 pts.wt. of active carbon fibers, 25-100 pts.wt. of pulp of fibrilated thermoplastic synthetic fibers, and 30-200 pts.wt. of reinforcing fibers, and the active carbon powder is fixed on the fibrils of the pulp by melting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water purifying sheet filter medium capable of adsorbing and removing organic substances contained in water and decomposing and removing free residual chlorine.

[0002]

2. Description of the Related Art Water purification filters are mainly used for the purpose of removing organic substances and chlorine odors in drinking water, and in recent years, as represented by faucet direct connection type water purifiers, downsizing of water purifiers has progressed, Filling the limited space, yet
It is desired to improve the performance of activated carbon so that the water purification performance higher than before can be obtained.

At present, granular activated carbon having a particle size of more than 150 μm is generally used for removing free residual chlorine, which is a causative substance of organic substances and chlorine odor, and the granular activated carbon is filled in a container such as a plastic case. Often used. However, the granular activated carbon cannot be expected to improve the performance of adsorbing and removing organic substances and the performance of decomposing and removing free residual chlorine, so-called water purification performance.

The reason is that the adsorption removal of organic substances from water and the decomposition removal of free residual chlorine are caused by the contact efficiency between activated carbon and water,
That is, the larger the outer surface area of activated carbon, the more it improves.However, since the outer surface area of granular activated carbon cannot be made large due to the size of its particle size, it improves organic matter adsorption removal performance and free residual chlorine decomposition removal performance, so-called water purification performance. Because there is a limit. Therefore, powdered activated carbon and activated carbon fiber have been studied as alternatives to the granular activated carbon.

Powdered activated carbon having a particle size of 150 μm or less has a large outer surface area, good contact efficiency with water, and higher water purification performance than granular activated carbon. However, since the powdered activated carbon is fine, it is not easy to handle, and there is a problem in that it flows out when passing water. Therefore, it has been considered to process the powdered activated carbon into a sheet shape or the like which has good handleability and is easy to filter-form.

Japanese Unexamined Patent Publication (Kokai) No. 3-122008 proposes an activated carbon sheet having a composition in which fibrillated fluororesin is dispersed in powdered activated carbon and a method for producing the same. However, this sheet is not a single-layer sheet, but is laminated so that it has a thickness of several mm, and it is used as water purification by passing water perpendicularly to the sheet. In addition, the activated carbon powder is not held by adhesion or fusion but is mechanically held by the fibrillated fluororesin, so that the activated carbon powder tends to flow out when passing water.

On the other hand, activated carbon fibers can be obtained in the form of sheets such as felt and paper that are easy to filter-form, and have the advantage that the water purification performance per unit weight is superior to that of granular activated carbon. Due to the high rigidity of the activated carbon fiber, the packing density of the sheet becomes low, and as a result, there is a problem that the water purification performance per unit volume is only about granular activated carbon.

On the other hand, Japanese Unexamined Patent Publication No. 63-283749 proposes a wet-molded body in which activated carbon fibers are crushed into a slurry and then sucked into a mold, and a manufacturing method thereof. In this method, if activated carbon fibers are crushed and the fiber length is shortened, a relatively high packing density molded body can be produced. However, if the activated carbon fiber content is high, the molded body strength is weak and Cracks and cracks easily form due to pressure fluctuations and pressure increases due to clogging. Therefore, in order to obtain the strength of the molded body that can withstand practical use, the content of the reinforcing material such as the binder must be increased, and the content of the activated carbon fiber becomes relatively small. Only the water purification performance of can be obtained.

[0009]

SUMMARY OF THE INVENTION In view of the above points, the present invention has a high water purification performance in adsorbing and removing organic substances contained in water, and particularly in decomposing and removing free residual chlorine, while maintaining a pressure loss during water passage. (EN) Provided is a sheet filter medium for water purification, which has a low water content and is easy to filter-form without causing the outflow of activated carbon.

[0010]

As a result of measuring the free residual chlorine removal performance of various powdered activated carbons, the present inventors have found that the pore volume of pore diameters of 30 to 300 angstroms is 0.15 cc / g or more. It was found that the performance of the powdered activated carbon possessed is extremely superior to that of the powdered activated carbon having a pore volume of generally 30 to 300 angstroms of less than 0.15 cc / g, and the adsorption and removal of organic matter contained in water is performed. In order to obtain a sheet filter material for water purification that has high water purification performance, low pressure loss during water passage, and does not cause outflow of powdered activated carbon, in particular, in the decomposition and removal of free residual chlorine, make a mixed paper sheet of the powdered activated carbon. As a result of examination, the present invention has been reached.

The present invention has a particle size of 10 to 150 μm and a pore volume of 30 to 300 angstrom and a volume of 0.1.
A sheet containing 10 to 200 parts by weight of activated carbon fiber, 25 to 100 parts by weight of pulp made of fibrillated thermoplastic synthetic fiber, and 30 to 200 parts by weight of reinforcing fiber to 100 parts by weight of powdered activated carbon of 5 cc / g or more. The present invention relates to a sheet filter medium for water purification, characterized in that powdered activated carbon is retained by fusion bonding of fibrils of pulp made of thermoplastic synthetic fiber.

In the present invention, the most important requirement is that the powdered activated carbon has a pore volume with a pore diameter of 30 to 300 angstroms of 0.15 cc / g or more. The pore volume of 30 to 300 angstrom is 0.15.
The peculiar activated carbon having a residual residual chlorine removal performance of cc / g or more is the same as that of ordinary activated carbon having the same weight and the same particle diameter and specific surface area (pore volume of 30 to 300 angstrom is 0.15 cc / g. Less than 5 times).

Free residual chlorine exists as hypochlorous acid in water, and hypochlorous acid is decomposed by a reduction reaction at a reaction active point on the surface of activated carbon, which is a mechanism of removal of free residual chlorine by activated carbon. Is. It is not clear what causes the excellent residual free chlorine removal performance of the specific activated carbon having a pore volume of 0.15 cc / g or more with a pore diameter of 30 to 300 angstrom, but this reaction active point is the above specific pore. It is conceivable that many of them are present in the pores having a diameter, and that water containing hypochlorous acid easily penetrates into the pores having a pore diameter of 30 Å or more.

In the present invention, as the powdered activated carbon, there is used one obtained by activating and pulverizing raw material carbon such as regenerated cellulose, wood pulp, sawdust, coconut husk, coal and phenol by a special method described later. It is important that these powdered activated carbons have a particle size of 10 to 150 μm. Particle size is 15
When it exceeds 0 μm, the outer surface area of the activated carbon becomes small, so that the water purification performance becomes poor, and when the particle size becomes smaller than 10 μm, the outflow of the activated carbon from the sheet filter for water purification becomes large.

The particle size of the activated carbon is a particle size corresponding to 50% of the volume-based cumulative particle size distribution measured by the light transmission measuring method by the natural sedimentation / centrifugal sedimentation method, and is an automatic particle size distribution measuring device (manufactured by Horiba Ltd. It measured using CAPA-500).

The pore diameter and pore volume of activated carbon are
Using the nitrogen gas adsorption isotherm on the adsorption side at the boiling point of liquid nitrogen under normal pressure (-198.8 ° C.), it was determined by the Craston-Inkley calculation method.

As a method for obtaining the above-mentioned powdered activated carbon having a large pore volume at a specific pore diameter, for example,
After impregnating regenerated cellulose activated carbon with an oxidation catalyst such as ferric chloride or magnesium acetate, it is subjected to reactivation treatment under a high-temperature steam gas atmosphere and then pulverized, or after fine powder of wood pulp or sawdust is carbonized, 900- It may be highly activated in a combustion gas atmosphere containing high temperature steam at 1300 ° C., but is not particularly limited.

In the present invention, 100 parts by weight of powdered activated carbon having a particle size of 10 to 150 μm is added to activated carbon fiber 10 to 10 parts by weight.
200 parts by weight, 25-100 parts by weight of pulp made of fibrillated thermoplastic synthetic fibers, reinforcing fibers 30-200
As a method for forming a sheet containing parts by weight, there is a wet papermaking method, in which case a flocculant, a stabilizer and the like may be added to a slurry containing a uniform mixture of the sheet materials.

In the present invention, it is important that the powdered activated carbon is trapped in the fibrils of pulp made of fibrillated thermoplastic synthetic fibers and held by fusion of the fibrils. This requirement is that after forming a homogeneous mixture containing powdered activated carbon, activated carbon fiber, fibrillated thermoplastic synthetic fiber, and reinforcing fiber into a sheet, the melting point of the fibrillated thermoplastic synthetic fiber is not less than It can be achieved by heating within a temperature range of melting point + 10 ° C. or less. By heating within this temperature range, only the fibrils of pulp are melted, and the powdered activated carbon is fusion-held by the minimum resin coating on the activated carbon surface. Below the melting point of the pulp, the powdered activated carbon is not fused and is only mechanically held, so that the powdered activated carbon easily flows out. On the other hand, when heated at a temperature higher than the melting point + 10 ° C., the entire pulp is melted and many parts of the activated carbon surface are covered with the melted resin, and the water purification performance is significantly lowered.

In the present invention, fibril means several nm to several μ.
A pulp composed of a fibrillated thermoplastic synthetic fiber refers to a fine fibrous structure having a thickness of m, and is a thermoplastic synthetic fiber having a large number of branched fibrils, such as polyethylene, polypropylene, and polystyrene. System, polyvinyl alcohol system, etc., and these pulps can be used.

A homogeneous mixture containing powdered activated carbon, activated carbon fiber, fibrillated thermoplastic synthetic fiber pulp, and reinforcing fiber is formed into a sheet, and thereafter, the melting point is not lower than the melting point of the fibrillated thermoplastic synthetic fiber pulp. +
The method of heating within a temperature range of 10 ° C. or lower is not particularly limited, but it can be performed simultaneously with drying in a drying step after forming into a sheet by a wet papermaking method.

In general, a sheet prepared by mixing powdered activated carbon has a high packing density, which is problematic because of high pressure loss for water purification applications in which water is passed through the sheet at right angles. The rigidity of the fibers results in a low packing density of the sheet. Therefore, in the present invention, activated carbon fibers 10 to 20 are added to 100 parts by weight of activated carbon powder.
By blending 0 parts by weight, preferably 30 to 150 parts by weight, and more preferably 50 to 100 parts by weight, a sheet having a packing density suitable for water purification applications can be obtained.

The activated carbon fiber has a fiber diameter of 5 to 50 μm.
m and a specific surface area of 500 to 2000 m ² / g can be used. Further, the raw material is not limited, and may be any of cellulose type, polyacrylonitrile type, phenol resin type, pitch type and the like.

In the present invention, the synthetic pulp comprising fibrillated thermoplastic synthetic fibers is 25 to 100 parts by weight, preferably 30 to 100 parts by weight, based on 100 parts by weight of powdered activated carbon.
80 parts by weight, more preferably 40 to 60 parts by weight, is added. Below this range, the amount of powdered activated carbon that is not retained in the fibrils of the synthetic pulp increases, and the outflow of powdered activated carbon easily occurs. Above this range, the amount of powdered activated carbon contained in the water purification sheet filter medium is relatively small. Therefore, the water purification performance deteriorates.

The water-purifying sheet filter medium of the present invention is often actually used as a molded body that is rolled into a cylindrical shape, but if the sheet strength is weak during the production of the molded body, workability deteriorates. Therefore, in order to obtain the strength of the sheet filter for water purification, in the present invention, the reinforcing fiber is 30 to 200 parts by weight, preferably 50 to 100 parts by weight with respect to the powdered activated carbon.
150 parts by weight, more preferably 50 to 100 parts by weight, is added. If it is less than this range, the strength of the water purification sheet filter medium is not sufficient, and if it exceeds this range, the amount of powdered activated carbon contained in the water purification sheet filter medium becomes relatively small and the water purification performance deteriorates.

In the present invention, examples of the reinforcing fiber include semi-synthetic fibers such as cellulose and viscose, polyester, polyolefin, polyamide, acrylic, polysulfone, polyamideimide, polyimide, polyphenylene sulfide, polyvinylidene fluoride, and the like. There are inorganic fibers such as glass, carbon, and metal, and these can be used alone or in combination. Hereinafter, the present invention will be described in more detail with reference to Examples.

[0027]

EXAMPLES The present invention will be described in detail based on examples, but the present invention is not limited to these examples. The evaluation method used in the present invention is described below. 1) Sheet strength A sheet filter for water purification is cut into a width of 15 mm in the length direction, and J
The breaking strength was measured at a pulling speed of 20 mm / min according to IS P8113 to evaluate the sheet strength.

2) Amount of activated carbon outflow A sheet of filter medium for water purification was punched out to a diameter of 47 mm, and water 300
It was put in a 500 ml beaker containing ml and stirred with a magnetic stirrer at 500 rpm for 5 minutes, and the outflow amount of activated carbon was evaluated by the weight reduction rate of the sheet.

3) Removal performance of free residual chlorine A sheet filter for water purification has an inner diameter of 30 with many holes on the circumference.
mm, outer diameter 34 mm, length 245 mm, wrapped around a polypropylene pipe to an outer diameter of 65 mm, then the outermost layer has a polypropylene core and a sheath has a melting point of 1
Fabric weight 16 composed of polyethylene composite fiber at 30 ℃
A non-woven fabric of g / m ² was wound, and a metal plate heated to 135 ° C. was applied and fixed by heat fusion to obtain a water purification filter molded body.

After sealing materials made of silicone rubber were attached to both end surfaces of the purified water filter molded body, the purified water filter molded body was mounted on a commercially available housing for a 10-inch cartridge filter. Water having a free residual chlorine concentration adjusted to 2 ppm was supplied to the housing at a flow rate of 5 liters / minute, and the total water flow amount until the free residual chlorine concentration in the water discharged from the housing reached 0.4 ppm was measured. ,
The free residual chlorine removal performance of the water purification filter molded body was evaluated. The free residual chlorine concentration is measured by a direct reading water quality analyzer (HA
It was measured by the DPD method using CH-made DR-2000).

4) Pressure Loss The water purification filter molded body obtained above was mounted on a commercially available housing for a 10-inch cartridge filter,
Water was supplied at a flow rate of 5 l / min, and the pressure loss was measured.

[0032]

Example 1 A particle size of 19μ obtained by crushing sawdust carbides after highly activated in a combustion gas atmosphere containing high temperature steam.
m, specific surface area 1150 m ² / g, pore diameter 30 to 300
100 parts by weight of activated carbon powder having an Angstrom pore volume of 0.21 cc / g, fiber diameter of 18 μm, specific surface area of 1450
100 parts by weight of m ² / g cellulosic activated carbon fiber, 67 parts by weight of polyethylene pulp having a melting point of 132 ° C., and 33 parts by weight of polyester fiber having a melting point of 255 ° C., a fiber fineness of 1.5 denier and a fiber length of 10 mm as reinforcing fibers. 33 parts by weight of a composite fiber having a fiber fineness of 2 denier and having a core of polypropylene and a sheath of polyethylene having a melting point of 130 ° C. is dispersed in water to prepare a uniform slurry, which is formed into a sheet by a wet papermaking method, and the sheet is formed at 135 ° C. for 5 minutes. Heated. The obtained sheet had a basis weight of 86 g / m ² , a thickness of 0.60 mm, and a packing density of 0.143 g / cc. Further, it was observed by a microscope that the powdered activated carbon was fused and held by the pulp fibrils.

[0033]

EXAMPLE 2 Ferric chloride was impregnated on regenerated cellulosic fibrous carbon, which was highly activated and pulverized to obtain a particle size of 15 μm, a specific surface area of 1500 m ² / g, and a pore diameter of 30 to 300 angstrom. Powdered activated carbon with a pore volume of 0.35 cc / g 1
00 parts by weight, fiber diameter 18 μm, specific surface area 1450 m ² /
g of cellulosic activated carbon fiber, melting point 132
50 parts by weight of polyethylene pulp at 70 ° C., and a reinforcing fiber made of polypropylene having a core of polypropylene and a sheath having a melting point of 130 ° C. Polyethylene having a fiber fineness of 2 denier 75
Parts by weight were dispersed in water to prepare a uniform slurry, which was formed into a sheet by a wet papermaking method and heated at 135 ° C. for 5 minutes. The obtained sheet has a basis weight of 45 g / m ² and a thickness of 0.
It was 20 mm and the packing density was 0.225 g / cc. Further, it was observed by a microscope that the powdered activated carbon was fused and held by the pulp fibrils.

[0034]

Example 3 A particle size of 17 obtained by highly activating and pulverizing a carbide of wood pulp in a combustion gas atmosphere containing high temperature steam.
μm, specific surface area 1020 m ² / g, pore diameter 30 to 30
100 parts by weight of powdered activated carbon having a pore volume of 0 Å, 0.44 cc / g, fiber diameter 18 μm, specific surface area 145
100 parts by weight of 0 m ² / g cellulosic activated carbon fiber,
67 parts by weight of polyethylene pulp having a melting point of 132 ° C., a reinforcing fiber having a melting point of 255 ° C., a fiber fineness of 1.5 denier,
33 parts by weight of a polyester fiber having a fiber length of 10 mm, 33 parts by weight of a composite fiber having a fiber fineness of 2 denier and made of polypropylene having a core of polypropylene and a sheath having a melting point of 130 ° C. are dispersed in water to prepare a uniform slurry. It was formed into a sheet and heated at 135 ° C for 5 minutes. The weight of the obtained sheet is 84 g / m ² , the thickness is 0.58 mm,
The packing density was 0.145 g / cc. Further, it was observed by a microscope that the powdered activated carbon was fused and held by the pulp fibrils.

[0035]

[Comparative Example 1] A raw coal of coconut husk was activated by steam and finely pulverized to obtain a particle diameter of 13 µm, a specific surface area of 1800 m ² / g, and a pore volume of 30 to 300 angstrom and a pore volume of 0.1.
100 parts by weight of 0 cc / g powdered activated carbon, 50 parts by weight of polyethylene synthetic pulp having a melting point of 132 ° C., reinforcing fiber having a melting point of 255 ° C., fiber fineness of 1.5 denier, fiber length of 1
50 parts by weight of 0 mm polyester fiber was dispersed in water to prepare a uniform slurry, which was formed into a sheet by a wet papermaking method and heated at 100 ° C. for 5 minutes. The weight of the obtained sheet was 84 g / m ² , the thickness was 0.30 mm, and the packing density was 0.280 g / cc.

[0036]

[Comparative Example 2] A raw coal of coconut husk was activated by steam and finely pulverized to obtain a particle size of 13 µm, a specific surface area of 1800 m ² / g, and a pore volume of 30 to 300 angstrom and a pore volume of 0.1.
100 parts by weight of powdered activated carbon of 0 cc / g, fiber fineness of 7 denier, 100 parts by weight of cellulosic activated carbon fiber having a specific surface area of 1450 m ² / g, 67 parts by weight of polyethylene pulp having a melting point of 132 ° C., melting fiber of 255 ° C. as a reinforcing fiber, 33 parts by weight of polyester fiber having a fiber fineness of 1.5 denier and a fiber length of 10 mm, a polypropylene core, and a melting point of 1 sheath.
33 parts by weight of a composite fiber having a fiber fineness of 2 denier and made of polyethylene at 30 ° C. is dispersed in water to prepare a uniform slurry, which is formed into a sheet by a wet papermaking method, and then at 5 ° C. at 135 ° C.
Heated for minutes. The obtained sheet has a basis weight of 88 g / m ² ,
The thickness was 0.62 mm and the packing density was 0.142 g / cc.

[0037]

[Comparative Example 3] Grain size 19 obtained by highly activating and finely pulverizing sawdust carbide in a combustion gas atmosphere containing high temperature steam.
μm, specific surface area 1150 m ² / g, pore diameter 30 to 30
100 parts by weight of powdered activated carbon having a pore volume of 0 angstrom, 0.21 cc / g, fiber diameter 18 μm, specific surface area 145
250 parts by weight of 0 m ² / g cellulosic activated carbon fiber,
75 parts by weight of polyethylene pulp having a melting point of 132 ° C., polypropylene as a reinforcing fiber and melting point of 13 as a sheath as reinforcing fibers
28 parts by weight of a composite fiber having a fiber fineness of 2 denier made of polyethylene at 0 ° C. was dispersed in water to prepare a uniform slurry, which was formed into a sheet by a wet papermaking method, and heated at 135 ° C. for 5 minutes. The resulting sheet had a basis weight of 62 g / m ² , a thickness of 1.02 mm, and a packing density of 0.061 g / cc.

The evaluation results are shown in Table 1. Comparative Example 1 has a pore volume of 30 to 300 angstroms and a pore volume of 0.
A general powdered activated carbon of less than 15 cc / g is wet-papered with pulp and reinforcing fibers to form a sheet, but the powdered activated carbon is not fusion-held to the fibrils of the pulp, so the activated carbon has a large outflow amount. Also, since the packing density of the sheet filter medium is high, it shows a very high pressure loss,
The ability to remove free residual chlorine is also low.

In Comparative Example 2, general powdered activated carbon having a pore volume of 30 to 300 angstrom and a pore volume of less than 0.15 cc / g was wet paper-made with activated carbon fiber, pulp and reinforcing fiber to form a sheet. However, the ability to remove free residual chlorine is low.

In Comparative Example 3, peculiar powdered activated carbon having a pore diameter of 30 to 300 angstrom and a pore volume of 0.15 cc / g or more was wet paper-made with activated carbon fiber, pulp and reinforcing fiber to form a sheet. However, since the content of the activated carbon fiber is large, the packing density of the sheet filter medium is low, and the amount of the sheet filter medium that can be packed per unit volume cannot be increased, so that the free residual chlorine removing performance is low. Also,
Since the amount of reinforcing fibers was small, the sheet strength was low, and when wrapped around a polypropylene pipe at the time of producing a filter molded body, the sheet was broken and the workability was poor.

In comparison with the above comparative example, the particle size is 10 to 150.
An example in which a specific powdered activated carbon having a pore volume of 30 μm and a pore volume of 30 to 300 angstrom and a pore volume of 0.15 cc / g or more was wet paper-made into a sheet with a predetermined composition together with activated carbon fiber, pulp and reinforcing fiber. All had high free residual chlorine removal performance, low pressure loss, small outflow of activated carbon, and sheet strength sufficient to withstand molding.

[0042]

[Table 1]

[0043]

EFFECTS OF THE INVENTION As described above, the present invention has the excellent effects of high water purification performance, particularly high performance of removing residual residual chlorine, good flowability of activated carbon, good handleability, and low pressure loss during water passage. A sheet filter material for water purification having the above can be provided.

Claims (1)

[Claims] 1. A particle diameter of 10 to 150 μm and a pore diameter of 30 to
Pore volume of 300 angstrom is 0.15cc / g
With respect to 100 parts by weight of the above powdered activated carbon, 10 to 200 parts by weight of activated carbon fiber, 25 to 100 parts by weight of pulp made of fibrillated thermoplastic synthetic fiber, and 30 to reinforcing fiber.
A sheet filter medium for water purification, comprising a sheet containing 200 parts by weight, wherein the powdered activated carbon is retained by fusion of fibrils of pulp composed of thermoplastic synthetic fibers.