JPS6144969B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to fibrous activated carbon for dechlorination, which is particularly effective in removing chlorine from tap water. It is well known that tap water contains chlorine for disinfection. Such tap water has an inferior taste when used for drinking purposes, and if the chlorine content is too high, it may cause health and hygiene problems such as destruction of cell membranes. Furthermore, in pharmaceutical applications, residual chlorine in water may become a problem. Chlorine can be removed by boiling or aerating tap water, but this method requires a lot of effort and equipment and is not practical. Methods of using various inorganic sulfites as dechlorinators are also known, but these salts have side effects on the human body and cannot be used for drinking water. A relatively effective method is to adsorb and decompose chlorine using granular or powdered activated carbon, and for this purpose various water purifiers incorporating these activated carbons have been developed. However, granular activated carbon adsorbs and decomposes chlorine at a slow rate and requires a long contact time to completely remove chlorine. If the bed height of activated carbon is increased in an attempt to shorten the contact time, the pressure loss will increase and the equipment will become larger, which is disadvantageous. Powdered activated carbon is advantageous because it adsorbs and decomposes chlorine quickly and allows the height of the activated carbon layer to be reduced. The disadvantage is that the amount of water is significantly reduced. It has been proposed to use fibrous activated carbon (ACF) instead of such granular or powdered activated carbon. ACF has an adsorption rate that is 10 to 100 times higher than general granular activated carbon, making it possible to downsize the device and increase water flow rate, making it effective as a dechlorination agent.However, on the other hand, the packing density of granular activated carbon ACF is small, less than 1/10 of that of chlorine, which poses problems in terms of sustainability of its performance.Furthermore, ACF is expensive, which limits its usage, and it is not always satisfactory as a dechlorinator. In view of the above-mentioned circumstances, the present inventors have developed an ACF with excellent performance that enables inexpensive and effective water purification treatment.
As a result of studies to develop a dechlorination agent, the present invention was arrived at. That is, the present invention is obtained by activating a raw material fiber containing an aluminum compound and at least one compound selected from iron, manganese, calcium, magnesium, or titanium compounds, Aluminum from 0.05
This is a fibrous activated carbon for dechlorination which contains 0.5% by weight and 0.01 to 1% by weight of iron, manganese, calcium, magnesium or/and titanium. Such ACF has an excellent dechlorination effect and is extremely effective in purifying water. In particular, since the dechlorination effect is long-lasting, it is possible to purify a large amount of water with a small amount. The fibrous activated carbon of the present invention may have a specific surface area of 500 to 200 m ² /g and is derived by a known method from acrylonitrile fibers, cellulose fibers, pitch fibers, poval fibers, aromatic polyamide fibers, etc. Either method may be used. Fibrous activated carbon derived from acrylonitrile fibers has unique adsorption and catalytic performance due to the nitrogen atoms it contains, and has a high dechlorination effect itself, so the effects of the present invention are particularly remarkable. The raw material fibers in the present invention include acrylonitrile fibers, cellulose fibers, phenol resin fibers, pitch fibers, poval fibers, aromatic polyamide fibers, etc., and these fibers are prepared in an oxidizing atmosphere such as air or in an inert atmosphere. Refers to the fibers obtained by processing the oxidized fibers before activation. Aluminum compounds, iron, and
Manganese, calcium, magnesium, titanium compounds are inorganic salts, organic salts, oxides, etc. of these metals. For example, aluminum compounds include polyaluminum chloride, aluminum sulfate, aluminum nitrate, aluminum phosphate, aluminum oxide,
Basic aluminum acetate, etc., and iron compounds include ferric chloride, ferric nitrate, and ferrous sulfate.
Examples include various compounds such as iron and ferric ammonium sulfate, and similar salts for other metal compounds. These metal compounds need to be contained in the raw material fiber. It is important that the material is incorporated into the raw fiber and then subjected to an activation treatment, or an oxidation treatment (flame resistance treatment) and an activation treatment to undergo a thermal history. These metal compounds have no effect even if they are attached to the fibrous activated carbon after the activation treatment. If this product is heat treated at 400°C or higher, the desired product can be obtained, but this is not preferable as it causes loss of fibrous activated carbon. Aluminum and other metals having the above-mentioned thermal history cannot exhibit an excellent dechlorination effect unless they are simultaneously contained in the fibrous activated carbon. For example, various fibrous activated carbons (nonwoven fabrics) with a specific surface area of 750 m ² /g obtained by oxidizing and then activating acrylic fibers containing aluminum, iron, calcium, and magnesium, either singly or simultaneously, have been deactivated. Comparing the effects of chlorine, it ranks first.
It is as shown in the table.

[Table] Chlorine concentration in test water From the above results, it is clear that the fibrous activated carbon of the present invention has excellent dechlorination performance. Although the reason for such an effect is unknown, it is thought that aluminum and other metals act as promoters to enhance the catalytic activity. In order to exhibit the effects of the present invention as described above, aluminum is used as a metal in an amount of 0.05 to 0.5% by weight, preferably 0.1 to 0.3% by weight, and one or more other metals are contained in an amount of 0.01 to 1% by weight, preferably 0.05～
It is necessary to contain it in a range of 0.5% by weight. Below these ranges, the dechlorination effect of the present invention will not be sufficient, and beyond this range, the surface area and pore volume of the fibrous activated carbon will decrease during activation, reducing the dechlorination effect and causing damage to the fibrous activated carbon. This is not preferred because mechanical performance is significantly impaired. The relationship between metal content and dechlorination effect for fibrous activated carbon with a specific surface area of 900 m ² /g is shown in Figure 2.
As shown in the table.

[Table] (Note) ○ indicates an example of the present invention. The method for obtaining the fibrous activated carbon for dechlorination of the present invention, for example, when acrylonitrile-based material is used as a raw material, is as follows. That is, an aluminum compound and a compound of iron, manganese, calcium, magnesium, and titanium are contained in either the acrylonitrile-based fiber or the acrylonitrile-based oxidized fiber. When it is added to acrylonitrile fibers, it may be added after the fibers are formed or it may be added to the polymer solution before spinning. In order to incorporate the metal compound into the raw material fibers, a commonly used application method such as preparing an aqueous solution of a predetermined metal compound and immersing the fibers in this solution or spraying the aqueous solution may be used. It is preferable to apply a metal compound to acrylonitrile fibers before oxidation treatment as raw material fibers, since this allows for uniform adhesion. The chemical structure of the metal compounds contained in the raw fibers changes due to oxidation or reaction with carbon during subsequent processes (oxidation treatment, activation treatment), but the metal elements remain in the fibrous activated carbon without scattering. Therefore, the amount added to the raw material fiber is determined according to the yield at the time of activation. The raw material fiber to which the metal compound has been added is subjected to oxidation treatment and activation treatment by a conventional method. As mentioned above, the oxidation treatment is carried out by heat treatment in an oxidizing atmosphere, for example, in air at 200 to 400°C under tension for 0.3 to 20 hours. In addition, the activation treatment is performed in an atmosphere of water vapor, carbon dioxide, ammonium, etc. at a temperature of 700°C or higher, preferably 850°C or higher.
This is done by heating at 1000°C for a few seconds to 2 hours. The fibrous activated carbon thus obtained has a specific surface area of 500 to 2000 m ² /g. Generally, as the specific surface area of fibrous activated carbon increases, the dechlorination effect increases, but when the specific surface area is 1000 m ² /g or more, the dechlorination effect tends to be saturated, and the price increases as the specific surface area increases. preferably 700
A range of ~1000 m ² /g is preferable. In addition, even if it has a high specific surface area, if it does not contain the metal of the present invention,
Needless to say, it does not exhibit an excellent dechlorination effect. The present invention will be specifically explained below using Examples. Example 1 Acrylonitrile fiber bundle (fineness: 3
Denier, total denier 540,000), Al ₂
(OH) _2.8 (SO _{4 ) 0.8 Cl 1.8} It was immersed in a dilute aqueous solution of polyaluminum chloride and ferric chloride, and squeezed and dried to give 0.03% by weight of aluminum and 0.03% iron _. A fiber bundle with 0.05% by weight attached was obtained. A fiber bundle having 0.03% by weight of aluminum and 0.1% by weight of calcium attached was obtained in the same manner using calcium chloride instead of the ferric chloride. These two types of fiber bundles were each placed in the air for 250 min.
The fibers were oxidized for 1 hour at 270°C and then for 1.3 hours at 270°C to obtain oxidized fibers with a specific gravity of 1.40. The two types of oxidized fibers obtained were each treated in steam at 900°C to produce a fibrous activated carbon having a specific surface area of 800 m ² /g and containing 0.11% by weight of aluminum and 0.19% by weight of iron. A fibrous activated carbon containing 0.11% by weight of aluminum and 0.3% by weight of calcium was obtained. These two types of fibrous activated carbon were each processed into a felt shape using a nonwoven fabric manufacturing apparatus, and their dynamic adsorption performance for chlorine was measured as follows. That is, a glass adsorption tower with an inner diameter of 75 mm was filled with 20 g of these fibrous activated carbons (absolutely dry) to a bed height of 100 mm, and tap water containing 2 ppm chlorine was continuously poured into this at a flow rate of 10/min. The chlorine concentration in the water that passed through the activated carbon layer was measured. For comparison, similar measurements were performed on the same fibrous activated carbon as above except that it did not contain metal, and on commercially available granular activated carbon (Shirasagi S, manufactured by Takeda Pharmaceutical Co., Ltd.). However, 300g of granular activated carbon was filled. The breakthrough curves for each activated carbon of the above-mentioned inventive examples and comparative examples are shown in Figure 1, and the effective adsorption amount (adsorption amount up to outlet concentration/inlet concentration = 0.05) is calculated from this curve as shown below. As shown in Table 3.

[Table] As is clear from the results, the fibrous activated carbon of the present invention has an effective adsorption amount that is 2 to 10 times higher than that of the comparative example, and this excellent dechlorination effect makes it possible to purify water. When used in containers, it is extremely economical as only a small amount is required. Example 2 Titanium dioxide with a particle size of 0.1 to 0.3μ was added to a polymer solution (concentration 10%) consisting of 5.3% by weight of methyl acrylate and 94.7% by weight of acrylonitrile, and spun to obtain a fineness of 2 denier and a total denier of 560,000 denier. , a fiber with a titanium oxide content of 0.1% by weight was added with aluminum sulfate. This fiber was heated in air at 250℃ for 1 hour, then
Oxidation treatment was performed at 270°C for 1.5 hours. The obtained oxidized fibers were immersed in an aqueous magnesium chloride solution, passed through a crimper to be crimped, and then made into oxidized fiber felt using a nonwoven fabric manufacturing device. The above oxidized fiber felt was treated in steam at 930°C to obtain a specific surface area of 1000 m ² /g, aluminum, titanium, and magnesium content of 0.25% by weight each.
Fibrous activated carbon (felt) of 0.3% by weight and 0.02% by weight was obtained. A cartridge was prepared by winding 25 g of this product around a cylinder having an inner diameter of 30 mm and a length of 250 mm and having a large number of small holes. Place this cartridge in the water purifier as shown in Figure 2 and move from the outside of the cartridge to the inside.
The performance of the cartridge was examined by passing water containing 1 ppm chlorine at a flow rate of 10/min. For comparison, fibrous activated carbon (felt) with a specific surface area of 1000 m ² /g was obtained by activating fibers that were exactly the same as the acrylic oxidized fibers except that they did not contain metal. A cartridge was made from this material in a similar manner and a water flow test was conducted. The above results are shown in Table 4.

[Table] Example 3 Phenol resin (trade name: Kynol) was immersed in a mixed aqueous solution of aluminum sulfate and manganese acetate (PH 4 or less) to contain 0.09% by weight of aluminum and 0.043% by weight of manganese, and then steamed at 900°C. 0.36% by weight of aluminum by activation treatment in
Specific surface area 1470m ² / containing 0.17% manganese by weight
g of fibrous activated carbon was obtained. The dynamic adsorption performance of this fibrous activated carbon for chlorine was measured using the same method as that used in Example 1. As a comparative example, fibrous activated carbon derived from the above raw material fibers and containing no metal;
The performance against chlorine was similarly evaluated for those containing either aluminum or manganese, and those containing both aluminum and manganese but whose content was outside the scope of the present invention. The results are summarized in Table 5.

【table】 [Brief explanation of the drawing]

FIG. 1 is a chlorine adsorption breakthrough curve diagram of various activated carbons of the present invention example and comparative example in Example 1, and FIG. 2 is a water purifier in which a cartridge of fibrous activated carbon is set. 1: Water purifier, 2: Cartridge.

Claims (1)

[Claims] 1. It is obtained by activating raw material fiber containing an aluminum compound and at least one compound selected from iron, manganese, calcium, magnesium, or titanium compounds, and contains 0.05 to 0.5 of aluminum as the metal. A fibrous activated carbon for dechlorination containing 0.01 to 1% by weight of iron, manganese, calcium, magnesium or/and titanium.