CA1151634A - Activated fibrous carbon - Google Patents
Activated fibrous carbonInfo
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- CA1151634A CA1151634A CA000331422A CA331422A CA1151634A CA 1151634 A CA1151634 A CA 1151634A CA 000331422 A CA000331422 A CA 000331422A CA 331422 A CA331422 A CA 331422A CA 1151634 A CA1151634 A CA 1151634A
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Abstract
Abstract A process for producing activated fibrous carbon comprises carbonizing and activating vegetable fibers in the presence of at least a member selected from the group consisting of ammonium salts of inorganic acids, nitric acid and boric acid as well as zinc chloride of about 5 to 80 parts by weight against 100 parts by weight of the vegetable fibers. The process increases remarkably a yield for activated fibrous carbon and there-fore permits the supply of activated fibrous carbon at by far reduced costs as compared with the conventional process, and the resulting activated carbon shows the superior adsorption capability and flexibility.
Description
~5~63~
The present invention relates to a method for producing activated fibrous carbon with the use of vegetable fibers as a raw material.
Activated fibrous carbon is easier to handle and is provided with the improved adsorption capacity, as compared with the powdered one, and has r0cently been drawing greater attraction as the adsorbent.
Activated fibrous carbon has been conventionally produced using acrylic fibers as ~he raw material. In such a conventional process, acrylic fibers are firstly subjected, under tension, to oxidation-treatment under an oxidizing atmosphere at a temperature of about 200 to 300C for a period of time as long as 10 to 20 hours to make them adequately flame-resistant. Thus treated, the materials are then burn~ in an atmosphere of steam at increased temperature up to about 900 to 1000C for a period of about 20 minutes to 3 hours, resulting in activated fibrous carbon.
This known process with the use of acrylic fibers as a raw material is accompanied with the disadvantages that a considerable length of time is required in the step of flame-resistance treatment and that the period of time and temperature for the step of activation must be prolonged and elevated.
There is also known a method for producing activated fibrous carbon comprising immersing cellulose based fibers such as cotton and rayons in an aqueous solution of zinc chloride, and effecting carbonization and activation at 500 to 800C after drying. However, it has been proved that the activated iibrous carbon is not necessarily satisfactory with regard to flexibility.
A thorough and extensive research study has been carried out by the present inventors who have shown that carbonization and activation of vegetable fibers in the presence of at least one member selected from the group consisting of ammonium salts of inorganic acids, boric acid and ni~ric ~i51634 acid as well as a particular ratio of zinc chloride lead to a remarkable increase in the yield of the activated fibrous carbon, along with improved adsorption capacity. It has been found, in particular, that an activated fibrous carbon with an increased degree of flexibility can be produced by carbonizing vegetable fibers in the presence of at least one member selected from the group consisting of ammonium salts of inorganic acids, boric acid and nitric acid, followed by activating the carbonized materials in the presence of zinc chloride of a specific ratio. Further, the yield for the activated fibrous carbon has been proved to be increased remarkably.
The present invention relates to a process for producing activated fibrous carbon comprising simultaneously or sequentially carbonizing and activating vegetable fibers in the presence of at least one member selected from the group consisting of nitric acid, boric acid and an ammonium salt of an inorganic acid as a first component, as well as zinc chloride as a second component in an amount of about 5 ot 80% by weight with respect to the total weight of the vegetable fibers, said first component being present at least during said carbonizing and said second component being present at least during said activating.
In a first embodiment, the vegetable fibres are simultaneously carbonized and activated in the presence of at least one member selected from the group consisting of nitric acid, boric acid and an ammonium salt of an inorganic acid as a first component as well as zinc chloride as a second component.
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In a second embodiment,the vegetable fibres are carbonized in the presence of at least one member selected from the group con-sisting of nitric acid, boric acid and an ammonium salt of an inorganic acid, and the carbonized materials are then activated in the presence of zinc chloride.
Preferably the carbonization temperature is about 250 to In other aspects the invention provides activated fibrous carbon products.
The vegetable fibers which are useful in the present invention include all fibers obtained from plants as starting materials, and are exemplified by seed fibers (e.g. cotton, kapok, bombax cotton, silk cotton, vegetable silk, etc.), bast fibers (e.g. flax, hemp, jute, ramie, kenaf, sunn hemp, etc.), leaf fibers (e.g. Manila hemp, New Zealand flax, sisal hemp, pita fibers, etc.), fibers from fruits (e.g. coconuts, etc.), and others (e.g. rush, straws, fibers from seaweed algae, neetle, etc.) as well as regenerated artificial fibers based on cellulose such as viscose and cupra~monium rayons and semi-synthetic fibers based on cellulose such as acetate fibers and acetylated staple fibers. These fibers may be in the fibrous form or may be in the form of fiber structures such as a woven fibrics, non-- 2a -1~5163~
woven fabrics and felt paper.
As the ammDnium salts of inorganic acids, which are useful in the presen~ invention, are mentioned, for example, ammonium chloride, ammonium nitrate, ammonium sulfat0~ ammonium phosphate, diammonium hydrogen phosphate, amnonium borate, ammonium phosphite, etc., and, among these ammonium salts, ammonium chloride yields the preferred results.
In the present invention, vegetable fibers are carbonized and activated. In the event that the carbonization and activation step is carried out without being divided in two stages, as described later, at least a member selected from the group consisting of ammonium salts of inorganic acids, nitric acid and boric acid, as well as zinc chloride are ordinarily supported on vegetable fibers. Preferably, the supported amounts of them for vegetable fibers, when expressed on the basis of 100 parts by weight of the vegetable fibers, are about 0.5 to 25 parts by weight and preferably, about 10 to 20 parts by weight, in the case of ammonium salts of inorganic acids; about 0.1 to 10 parts by weight, and preferably, about 0.5 to 5 parts by weight, in the case of nitric acid; about 0.1 to 10 parts by weight, and preferably, about 0.5 to 5 parts by weight, in the case of boric acid; and, about 5 to 80 parts by weight, and preferably about 10 to 30 parts by weight, in the case of zinc chlorid0.
The means of supporting the aforementioned compounds on vegetable fibers are for example by immersing vegetable fibers in solutions of the aforementioned compounds, or by spraying solutions of the aforementioned compounds over vegetable fibers.
A concentration in solution of ammonium salts of inorganic acids, nitric acid or boric acid, though being variable with the selected compound, is preferably about 1 to 30% by weight in the case of ammonium salts of inorganic acids; about 0.1 to 5% by weight in the case of nitric acid; and, ~:~5~
about 0.1 to 5% by weiyht in the case of boric acid.
The solutions may be aqueous or those containing alcohol, etc.
A concentration of the solution of zinc chloride is about 5 to 60% by weight, and preferably, about 10 to 50% by weight. In order to increase the solubility of zinc chloride, hydrochloric acid and alcohols may be added, for example, in an amount of up to about 5~ by weight against the whole solution.
The temperature of carbonization and activation is preferably about 400 to 750C, and more preferably, 450 to 650C, while the length of time thereof is about 0.25 to 2 hours, and preferably, about 0.5 to 1 hour. Such a process or operation is ordinarily carried out, for example, in a furnace such as electric and gas-fired furnaces. The heating-up rate, at which the temperature inside the furnace is allowed to reach the prescribed temperatures as mentioned above, is about 5 to 75C/min, and preferably, about 10 to 45C/min. Alternatively, heating may be effected to attain the prescribed temperature after placing vegetable fibers inside a furnace which has been warmed in advance up to an inner temperature of about 100 to 200C. Carbonization and activation are ordinarily carried out in an atmosphere of inert gas such as nitrogen gas, and waste combustion gas from heavy oil, light oil, ~erosene, etc.
In the present invention, the above described operation may be conducted, in two stages of carbonization and activation of vegetable fibers. In this case, vegetable fibers are in the first place carbonized, in the presence of at least a member selected from the group consisting of ammonium salts of inorganic acids, nitric acid and boric acid, in an atmosphere of inert gas as described above, at a temperature of about 250 to 450C, and preferably, about 0.5 to 1 hour. The carbonized materials thus obtained are then activated in the presence of zinc chloride. At least one member - 4a -~1, ~IS163~
selected from the group consisting of ammonium salts of inorganic acids, nitric acid and boric acid, together with zinc chloride, which are used in the aforementioned operations, are ordinarily supported on vegetable fibers and their carboni~ed materials, respectively. Means of supporting zinc chloride on carbonized materials consist for example, of immersing car-bonized materials in a solution of zinc chloride, and of spraying a solution of zinc chloride over carbonized materials. The supported amount of zinc chloride is about 30 to 200 parts by weight, and preferably, 50 to 150 parts by weight, as zinc chloride on the basis of 100 parts by weight of the car-bonized material. Activation is carried out by burning in an atmosphere ofnitrogen or waste combustion ~as from heavy oil, light oil, kerosene, etc., at a temperature of about 350 to 750C, for about 0.25 to 2 hours. In this case, the furnace is heated up in accordance with the operation as described above. When the steps of carbonization and activation for vegetable fibers are conducted separately in two stages, in the manner as described above, the resulting activated fibrous carbon possesses a particularly improved flexibi-lity. The activated fibrous carbon produced in this manner, if necessary, may be further subjected to washing and drying in accordance with conventional methods.
The method according to the present invention remarkably increases the yield of activated fibrous carbon, and can supply activated fibrous carbon at by far reduced costs, as compared with the conventional process, furthermore both adsorption capability and flexibility of the resulting activated carbon are superior.
Example I
Commercially available cotton cloth ~bleached cotton) is immersed for about 5 minutes in an aqueous solution containing 20% by weight of zinc chloride, 15.5% by weight of ammonium chloride and 1% by weight of hydrogen ~516;~4 chloride, and squeezed by use o~ rubber rollers to uniformly support the solution. The supported amounts of the chemicals are, on the basis of 100 g of the raw cloth, 23 g for zinc chloride, 17 g for ammonium chloride, and not more than 1 g for hydrogen chloride. The raw cloth supported with the chemical solution is wound up on a roll of 16-mesh wire net made of stainless steel, and carbonized and activated in a circular type electric urnace, i~
a s~ream of nitrogen gas, at a temperature of 600C, for about 1/2 hour, the heating-up rate is 15/min. The activated fibrous carbon A is obtained with a yield and adsorption capability as shown in Table 1.
Reference ExamPle 1 The activated fibrous carbon B is produced in the same manner as described in Example 1, while using an aqueous solution containing 20% by weight of zinc chloride and 0.2% by weight of hydrogen chloride. The yield and adsorption capability are shown in Table 1. The supported amoun~ of zinc chloride is 35 g/100 g o~ the raw cloth, and that of hydrogen chloride i5 not more than 1 ~/100 g of the raw cloth.
Example 2 Commercially available cotton cloth is immersed for about 5 minutes in an aqueous solution containing 25% by weight of zinc chloride, 2.5% by weight of boric acid and 2% by weight of hydrogen chloride, and then dehyd-rated by means of a centrifuge to have the chemical solution supported uniformly. The supported amounts of the chemicals, on the basis of 100 g of the raw cloth, are 36 g for zinc chloride, 6 g for boric acid, and about 1 g for hydrogen chloride. The raw cloth supported with the chemical solution is wound up on a 16-mesh wire net made of stainless steel, and carbonized and activated in a circular type electric furnace, in the stream of nitrogen gas, at a temperature of 550C, for 3/4 hour, to produce the activated fibrous carbon C. In this case, a heating-up rate is 30C/min. The yield and adsorption capabllity of the activated carbon C are as shown in Table 1.
Example 3 The activated fibrous carbon D is produced in the same manner as described in Example 2, except that an aqueous solution containing 25% by weight of zinc chloride, 12.5~ by weight of ammonium chloride, 5% by weight of boric acid and 1~ by weight of hydrogen chloride.is supported. The yield and adsorption capability of the activated carbon D are as shown in Table 1.
The supported amoun~s are 27 g of zinc chloride relative to 100 g of the raw cloth, 15 g of ammonium chloride relative to 100 g of the raw cloth, 5 g of boric acid relative to 100 g of the raw cloth, and not more than 1 g of hydrogen chloride relative to 100 g of the raw cloth, respectively.
Example 4 The activated fibrous carbon E is produced in the same manner as described in Example 1, except that an aqueous solution containing 15% by weight of zinc chloride, 2% by weight of nitric acid and 1% by weight of hydrogen chloride is supported. The yield and adsorption capability of the activated carbon E are as shown in Table 1.
The supported amounts are 20 g of zinc chloride relative to 100 g of the raw cloth, S g of nitric acid relative to 100 g of the raw cloth and not more than 1 g of hydrogen chloride relative to 100 g of the raw cloth.
Table 1 AdsorDtion caDabilitY
Acetone adsorption Activated fibrous ProductionBET surface capability*, _carbon yield, ~area, m2/g g/lOOg A.C.
Activated fibrous carbon A 46.7 890 19.2 " C 37-9 1170 25.3 " D 45.2 11100 23.8 " E 3~.0 805 19.1 ~5163~
Remarks:
*); Calculated on the basis ot increases in weight determined when adsorption is effected at 25C for 1.5 hours with the use of air containing 37.5 g/m3 of acetone.
Reference Example 2 Commercially available cotton cloth ~bleached cotton) is wound up on a 16-mesh net-like tube made of stainless steel, and carbonized in a silica glass tubel in the stream of nitrogen gas, at a temperature of 350C
for 0.5 hour. The heating-up rate is 15C/min. Following carbonization, inspection after being cooled down to ambient temperature reveals 21% of the carbonization yield. The carbonized materials are immersed for about 5 minutes in an aqueous solution containing 20% by weight of zinc chloride and 1% by weight of hydrogen chloride, and squeezed to remove the excessive solution by rubber rollers, whereby to support zinc chloride uniformly; the supported amolmt is 67 g as zinc chloride/100 g of the carbonized material.
The carboni~ed materials are activated in the stream of nitrogen gas, at a temperature of 550C for 0.5 hour. In this case, the heating-up rate is 15C/min. Following the activation, the material is washed, refined and dried to obtain the activated fibrous carbon F with improved flexibility at a yield of 15~. The maximum amount of acetone to be adsorbed at 25C, when determined on the activated carbon F with the use of air having 37.5 g/m3 of the acetone concentration, is 21% by weight.
Example 5 Commercially available hemp cloth is immersed for 3 minutes in a previously prepared aqueous solution containing 3% by weight of boric acid, and squeezed by means of a centrifuge to be in~re~nated uniformly with boric acid of 2.5 g/100 g of the raw cloth. The cloth impregnated with the chemical solution is, in the same manner as described in Reference Example 2, carbonized at 350C for 0.75 hour. The carbonized material is impregnated with a solution containing 15% by weight of zinc chloride at a rate of 65 g as zinc chloride/100 g of the carbonized ma~erial, and activated at 550C
for 0.5 hour. Then, washing, refining, and drying result in the satisfactorily activated fibrous carbon G at a yield of 3~%. The acetone adsorption capabi-lity of the activated carbon G is 19.8%.
Example 6 Commercially available hemp cloth is immersed for 3 minutes in a previously prepared aqueous solution containing 15.5% by weight of ammonium chloride, and squeezed by means of rubber rollers, to be impregnated uniformly with ammonium chloride of 22 g as ammonium chloride/100 g of the raw cloth.
The cloth impregnated with the solution is, in the same manner as described in Reference Example 2, carbonized at 350C for 1 hour. The carbonized material is impregnated with a solution containing 40% by weight of zinc chloride at a rate of 120 g as zinc chloride/100 g of the carbonized msterial, and activated at 570C for 1 hour. Then, washing, refining and drying result in the satisfactorily activated fibrous carbon H in a yield of 40%. The acetone adsorption capability of the activated carbon is 22%.
Example 7 Commercially available cotton cloth (bleached cotton) is immersed for 5 minutes in a previously prepared aqueous solution containing 20% by weight of ammonium sulfate, and squeezed by means of a centrifuge for unitorm impregnation with the chemical solution at a rate of 18 g as ammonium sulfate/lO0 g of tlle raw cloth. The cloth impregnated with the solution is, in the same manner as described in Reference Example 2, carbonized at 350C
for 1 hour. The carbonized material is impregnated with a solution containing 40% by weight of zinc chloride at a rate of 118 g as zinc chloride/100 g of ~5~L63~
the carbonized material, and carbonized at 600C for 1 hour. Then, washing, refining and drying result in the satisfactorily activated fibrGus carbon I
in a yield of 39.8%. The acetone adsorption capability of the activated carbon is 22.5%.
The activated fibrous carbon to be prepared by the method according to the present invention is useful for -fective removal of organic substances, ill-odoring components, for example, 1. Purification of air in the buildings, restaurants, coffee-houses, hospitals, vehicles ~e.g. automobiles, railway vehicles, airplanes), and the like, Z. Prevention o~ bad or offensive smells in refuse-treatment plants, animal-breeding chambers, etc., 3. Removal of organic solvents to be exhausted from factories engaged in dry-cleaning, rubber processing or manufacture, metal-surface working, fiber reinforced-plastics fabrication, manufacture of synthetic fibers, cellophanes or films, paint application, etc., 4. Medical appliances or supplies such as artificial kidney, artificial liver and hygienic goods ~e.g. masks), 5. Filters to be tipped on cigarettes.
In the application fields mentioned under the i~ems 1 through 3, a filter cloth form may be utilized using activated fibrous carbon from raw materials vegetable fibers forming a fibrous structure material such as woven fabrics, non-woven fabrics and fel~ paper. In the case of the afore-mentioned item 4, the product produced from vegetable ~ibers of a ~ibrous structure material is wrapped by a gauze and the like. In the case mentioned above under the item 5, activated fibrous carbon is crushed, and dispersed in acetate fibers so as to be utilized in a filter form (fiber bundles).
The present invention relates to a method for producing activated fibrous carbon with the use of vegetable fibers as a raw material.
Activated fibrous carbon is easier to handle and is provided with the improved adsorption capacity, as compared with the powdered one, and has r0cently been drawing greater attraction as the adsorbent.
Activated fibrous carbon has been conventionally produced using acrylic fibers as ~he raw material. In such a conventional process, acrylic fibers are firstly subjected, under tension, to oxidation-treatment under an oxidizing atmosphere at a temperature of about 200 to 300C for a period of time as long as 10 to 20 hours to make them adequately flame-resistant. Thus treated, the materials are then burn~ in an atmosphere of steam at increased temperature up to about 900 to 1000C for a period of about 20 minutes to 3 hours, resulting in activated fibrous carbon.
This known process with the use of acrylic fibers as a raw material is accompanied with the disadvantages that a considerable length of time is required in the step of flame-resistance treatment and that the period of time and temperature for the step of activation must be prolonged and elevated.
There is also known a method for producing activated fibrous carbon comprising immersing cellulose based fibers such as cotton and rayons in an aqueous solution of zinc chloride, and effecting carbonization and activation at 500 to 800C after drying. However, it has been proved that the activated iibrous carbon is not necessarily satisfactory with regard to flexibility.
A thorough and extensive research study has been carried out by the present inventors who have shown that carbonization and activation of vegetable fibers in the presence of at least one member selected from the group consisting of ammonium salts of inorganic acids, boric acid and ni~ric ~i51634 acid as well as a particular ratio of zinc chloride lead to a remarkable increase in the yield of the activated fibrous carbon, along with improved adsorption capacity. It has been found, in particular, that an activated fibrous carbon with an increased degree of flexibility can be produced by carbonizing vegetable fibers in the presence of at least one member selected from the group consisting of ammonium salts of inorganic acids, boric acid and nitric acid, followed by activating the carbonized materials in the presence of zinc chloride of a specific ratio. Further, the yield for the activated fibrous carbon has been proved to be increased remarkably.
The present invention relates to a process for producing activated fibrous carbon comprising simultaneously or sequentially carbonizing and activating vegetable fibers in the presence of at least one member selected from the group consisting of nitric acid, boric acid and an ammonium salt of an inorganic acid as a first component, as well as zinc chloride as a second component in an amount of about 5 ot 80% by weight with respect to the total weight of the vegetable fibers, said first component being present at least during said carbonizing and said second component being present at least during said activating.
In a first embodiment, the vegetable fibres are simultaneously carbonized and activated in the presence of at least one member selected from the group consisting of nitric acid, boric acid and an ammonium salt of an inorganic acid as a first component as well as zinc chloride as a second component.
~S~
In a second embodiment,the vegetable fibres are carbonized in the presence of at least one member selected from the group con-sisting of nitric acid, boric acid and an ammonium salt of an inorganic acid, and the carbonized materials are then activated in the presence of zinc chloride.
Preferably the carbonization temperature is about 250 to In other aspects the invention provides activated fibrous carbon products.
The vegetable fibers which are useful in the present invention include all fibers obtained from plants as starting materials, and are exemplified by seed fibers (e.g. cotton, kapok, bombax cotton, silk cotton, vegetable silk, etc.), bast fibers (e.g. flax, hemp, jute, ramie, kenaf, sunn hemp, etc.), leaf fibers (e.g. Manila hemp, New Zealand flax, sisal hemp, pita fibers, etc.), fibers from fruits (e.g. coconuts, etc.), and others (e.g. rush, straws, fibers from seaweed algae, neetle, etc.) as well as regenerated artificial fibers based on cellulose such as viscose and cupra~monium rayons and semi-synthetic fibers based on cellulose such as acetate fibers and acetylated staple fibers. These fibers may be in the fibrous form or may be in the form of fiber structures such as a woven fibrics, non-- 2a -1~5163~
woven fabrics and felt paper.
As the ammDnium salts of inorganic acids, which are useful in the presen~ invention, are mentioned, for example, ammonium chloride, ammonium nitrate, ammonium sulfat0~ ammonium phosphate, diammonium hydrogen phosphate, amnonium borate, ammonium phosphite, etc., and, among these ammonium salts, ammonium chloride yields the preferred results.
In the present invention, vegetable fibers are carbonized and activated. In the event that the carbonization and activation step is carried out without being divided in two stages, as described later, at least a member selected from the group consisting of ammonium salts of inorganic acids, nitric acid and boric acid, as well as zinc chloride are ordinarily supported on vegetable fibers. Preferably, the supported amounts of them for vegetable fibers, when expressed on the basis of 100 parts by weight of the vegetable fibers, are about 0.5 to 25 parts by weight and preferably, about 10 to 20 parts by weight, in the case of ammonium salts of inorganic acids; about 0.1 to 10 parts by weight, and preferably, about 0.5 to 5 parts by weight, in the case of nitric acid; about 0.1 to 10 parts by weight, and preferably, about 0.5 to 5 parts by weight, in the case of boric acid; and, about 5 to 80 parts by weight, and preferably about 10 to 30 parts by weight, in the case of zinc chlorid0.
The means of supporting the aforementioned compounds on vegetable fibers are for example by immersing vegetable fibers in solutions of the aforementioned compounds, or by spraying solutions of the aforementioned compounds over vegetable fibers.
A concentration in solution of ammonium salts of inorganic acids, nitric acid or boric acid, though being variable with the selected compound, is preferably about 1 to 30% by weight in the case of ammonium salts of inorganic acids; about 0.1 to 5% by weight in the case of nitric acid; and, ~:~5~
about 0.1 to 5% by weiyht in the case of boric acid.
The solutions may be aqueous or those containing alcohol, etc.
A concentration of the solution of zinc chloride is about 5 to 60% by weight, and preferably, about 10 to 50% by weight. In order to increase the solubility of zinc chloride, hydrochloric acid and alcohols may be added, for example, in an amount of up to about 5~ by weight against the whole solution.
The temperature of carbonization and activation is preferably about 400 to 750C, and more preferably, 450 to 650C, while the length of time thereof is about 0.25 to 2 hours, and preferably, about 0.5 to 1 hour. Such a process or operation is ordinarily carried out, for example, in a furnace such as electric and gas-fired furnaces. The heating-up rate, at which the temperature inside the furnace is allowed to reach the prescribed temperatures as mentioned above, is about 5 to 75C/min, and preferably, about 10 to 45C/min. Alternatively, heating may be effected to attain the prescribed temperature after placing vegetable fibers inside a furnace which has been warmed in advance up to an inner temperature of about 100 to 200C. Carbonization and activation are ordinarily carried out in an atmosphere of inert gas such as nitrogen gas, and waste combustion gas from heavy oil, light oil, ~erosene, etc.
In the present invention, the above described operation may be conducted, in two stages of carbonization and activation of vegetable fibers. In this case, vegetable fibers are in the first place carbonized, in the presence of at least a member selected from the group consisting of ammonium salts of inorganic acids, nitric acid and boric acid, in an atmosphere of inert gas as described above, at a temperature of about 250 to 450C, and preferably, about 0.5 to 1 hour. The carbonized materials thus obtained are then activated in the presence of zinc chloride. At least one member - 4a -~1, ~IS163~
selected from the group consisting of ammonium salts of inorganic acids, nitric acid and boric acid, together with zinc chloride, which are used in the aforementioned operations, are ordinarily supported on vegetable fibers and their carboni~ed materials, respectively. Means of supporting zinc chloride on carbonized materials consist for example, of immersing car-bonized materials in a solution of zinc chloride, and of spraying a solution of zinc chloride over carbonized materials. The supported amount of zinc chloride is about 30 to 200 parts by weight, and preferably, 50 to 150 parts by weight, as zinc chloride on the basis of 100 parts by weight of the car-bonized material. Activation is carried out by burning in an atmosphere ofnitrogen or waste combustion ~as from heavy oil, light oil, kerosene, etc., at a temperature of about 350 to 750C, for about 0.25 to 2 hours. In this case, the furnace is heated up in accordance with the operation as described above. When the steps of carbonization and activation for vegetable fibers are conducted separately in two stages, in the manner as described above, the resulting activated fibrous carbon possesses a particularly improved flexibi-lity. The activated fibrous carbon produced in this manner, if necessary, may be further subjected to washing and drying in accordance with conventional methods.
The method according to the present invention remarkably increases the yield of activated fibrous carbon, and can supply activated fibrous carbon at by far reduced costs, as compared with the conventional process, furthermore both adsorption capability and flexibility of the resulting activated carbon are superior.
Example I
Commercially available cotton cloth ~bleached cotton) is immersed for about 5 minutes in an aqueous solution containing 20% by weight of zinc chloride, 15.5% by weight of ammonium chloride and 1% by weight of hydrogen ~516;~4 chloride, and squeezed by use o~ rubber rollers to uniformly support the solution. The supported amounts of the chemicals are, on the basis of 100 g of the raw cloth, 23 g for zinc chloride, 17 g for ammonium chloride, and not more than 1 g for hydrogen chloride. The raw cloth supported with the chemical solution is wound up on a roll of 16-mesh wire net made of stainless steel, and carbonized and activated in a circular type electric urnace, i~
a s~ream of nitrogen gas, at a temperature of 600C, for about 1/2 hour, the heating-up rate is 15/min. The activated fibrous carbon A is obtained with a yield and adsorption capability as shown in Table 1.
Reference ExamPle 1 The activated fibrous carbon B is produced in the same manner as described in Example 1, while using an aqueous solution containing 20% by weight of zinc chloride and 0.2% by weight of hydrogen chloride. The yield and adsorption capability are shown in Table 1. The supported amoun~ of zinc chloride is 35 g/100 g o~ the raw cloth, and that of hydrogen chloride i5 not more than 1 ~/100 g of the raw cloth.
Example 2 Commercially available cotton cloth is immersed for about 5 minutes in an aqueous solution containing 25% by weight of zinc chloride, 2.5% by weight of boric acid and 2% by weight of hydrogen chloride, and then dehyd-rated by means of a centrifuge to have the chemical solution supported uniformly. The supported amounts of the chemicals, on the basis of 100 g of the raw cloth, are 36 g for zinc chloride, 6 g for boric acid, and about 1 g for hydrogen chloride. The raw cloth supported with the chemical solution is wound up on a 16-mesh wire net made of stainless steel, and carbonized and activated in a circular type electric furnace, in the stream of nitrogen gas, at a temperature of 550C, for 3/4 hour, to produce the activated fibrous carbon C. In this case, a heating-up rate is 30C/min. The yield and adsorption capabllity of the activated carbon C are as shown in Table 1.
Example 3 The activated fibrous carbon D is produced in the same manner as described in Example 2, except that an aqueous solution containing 25% by weight of zinc chloride, 12.5~ by weight of ammonium chloride, 5% by weight of boric acid and 1~ by weight of hydrogen chloride.is supported. The yield and adsorption capability of the activated carbon D are as shown in Table 1.
The supported amoun~s are 27 g of zinc chloride relative to 100 g of the raw cloth, 15 g of ammonium chloride relative to 100 g of the raw cloth, 5 g of boric acid relative to 100 g of the raw cloth, and not more than 1 g of hydrogen chloride relative to 100 g of the raw cloth, respectively.
Example 4 The activated fibrous carbon E is produced in the same manner as described in Example 1, except that an aqueous solution containing 15% by weight of zinc chloride, 2% by weight of nitric acid and 1% by weight of hydrogen chloride is supported. The yield and adsorption capability of the activated carbon E are as shown in Table 1.
The supported amounts are 20 g of zinc chloride relative to 100 g of the raw cloth, S g of nitric acid relative to 100 g of the raw cloth and not more than 1 g of hydrogen chloride relative to 100 g of the raw cloth.
Table 1 AdsorDtion caDabilitY
Acetone adsorption Activated fibrous ProductionBET surface capability*, _carbon yield, ~area, m2/g g/lOOg A.C.
Activated fibrous carbon A 46.7 890 19.2 " C 37-9 1170 25.3 " D 45.2 11100 23.8 " E 3~.0 805 19.1 ~5163~
Remarks:
*); Calculated on the basis ot increases in weight determined when adsorption is effected at 25C for 1.5 hours with the use of air containing 37.5 g/m3 of acetone.
Reference Example 2 Commercially available cotton cloth ~bleached cotton) is wound up on a 16-mesh net-like tube made of stainless steel, and carbonized in a silica glass tubel in the stream of nitrogen gas, at a temperature of 350C
for 0.5 hour. The heating-up rate is 15C/min. Following carbonization, inspection after being cooled down to ambient temperature reveals 21% of the carbonization yield. The carbonized materials are immersed for about 5 minutes in an aqueous solution containing 20% by weight of zinc chloride and 1% by weight of hydrogen chloride, and squeezed to remove the excessive solution by rubber rollers, whereby to support zinc chloride uniformly; the supported amolmt is 67 g as zinc chloride/100 g of the carbonized material.
The carboni~ed materials are activated in the stream of nitrogen gas, at a temperature of 550C for 0.5 hour. In this case, the heating-up rate is 15C/min. Following the activation, the material is washed, refined and dried to obtain the activated fibrous carbon F with improved flexibility at a yield of 15~. The maximum amount of acetone to be adsorbed at 25C, when determined on the activated carbon F with the use of air having 37.5 g/m3 of the acetone concentration, is 21% by weight.
Example 5 Commercially available hemp cloth is immersed for 3 minutes in a previously prepared aqueous solution containing 3% by weight of boric acid, and squeezed by means of a centrifuge to be in~re~nated uniformly with boric acid of 2.5 g/100 g of the raw cloth. The cloth impregnated with the chemical solution is, in the same manner as described in Reference Example 2, carbonized at 350C for 0.75 hour. The carbonized material is impregnated with a solution containing 15% by weight of zinc chloride at a rate of 65 g as zinc chloride/100 g of the carbonized ma~erial, and activated at 550C
for 0.5 hour. Then, washing, refining, and drying result in the satisfactorily activated fibrous carbon G at a yield of 3~%. The acetone adsorption capabi-lity of the activated carbon G is 19.8%.
Example 6 Commercially available hemp cloth is immersed for 3 minutes in a previously prepared aqueous solution containing 15.5% by weight of ammonium chloride, and squeezed by means of rubber rollers, to be impregnated uniformly with ammonium chloride of 22 g as ammonium chloride/100 g of the raw cloth.
The cloth impregnated with the solution is, in the same manner as described in Reference Example 2, carbonized at 350C for 1 hour. The carbonized material is impregnated with a solution containing 40% by weight of zinc chloride at a rate of 120 g as zinc chloride/100 g of the carbonized msterial, and activated at 570C for 1 hour. Then, washing, refining and drying result in the satisfactorily activated fibrous carbon H in a yield of 40%. The acetone adsorption capability of the activated carbon is 22%.
Example 7 Commercially available cotton cloth (bleached cotton) is immersed for 5 minutes in a previously prepared aqueous solution containing 20% by weight of ammonium sulfate, and squeezed by means of a centrifuge for unitorm impregnation with the chemical solution at a rate of 18 g as ammonium sulfate/lO0 g of tlle raw cloth. The cloth impregnated with the solution is, in the same manner as described in Reference Example 2, carbonized at 350C
for 1 hour. The carbonized material is impregnated with a solution containing 40% by weight of zinc chloride at a rate of 118 g as zinc chloride/100 g of ~5~L63~
the carbonized material, and carbonized at 600C for 1 hour. Then, washing, refining and drying result in the satisfactorily activated fibrGus carbon I
in a yield of 39.8%. The acetone adsorption capability of the activated carbon is 22.5%.
The activated fibrous carbon to be prepared by the method according to the present invention is useful for -fective removal of organic substances, ill-odoring components, for example, 1. Purification of air in the buildings, restaurants, coffee-houses, hospitals, vehicles ~e.g. automobiles, railway vehicles, airplanes), and the like, Z. Prevention o~ bad or offensive smells in refuse-treatment plants, animal-breeding chambers, etc., 3. Removal of organic solvents to be exhausted from factories engaged in dry-cleaning, rubber processing or manufacture, metal-surface working, fiber reinforced-plastics fabrication, manufacture of synthetic fibers, cellophanes or films, paint application, etc., 4. Medical appliances or supplies such as artificial kidney, artificial liver and hygienic goods ~e.g. masks), 5. Filters to be tipped on cigarettes.
In the application fields mentioned under the i~ems 1 through 3, a filter cloth form may be utilized using activated fibrous carbon from raw materials vegetable fibers forming a fibrous structure material such as woven fabrics, non-woven fabrics and fel~ paper. In the case of the afore-mentioned item 4, the product produced from vegetable ~ibers of a ~ibrous structure material is wrapped by a gauze and the like. In the case mentioned above under the item 5, activated fibrous carbon is crushed, and dispersed in acetate fibers so as to be utilized in a filter form (fiber bundles).
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for producing activated fibrous carbon comprising simultaneously or sequentially carbonizing and activating vegetable fibers in the presence of at least one member selected from the group consisting of nitric acid, boric acid and an ammonium salt of an inorganic acid as a first component, as well as zinc chloride as a second component in an amount of about 5 to 80% by weight with respect to the total weight of the vegetable fibers, said first component being present at least during said carbonizing and said second component being present at least during said activating.
2. A process as claimed in claim 1, wherein vegetable fibers are simultaneously carbonized and activated in the presence of at least one member selected from the group consisting of nitric acid, boric acid and an ammonium salt of an inorganic acid as a first component as well as zinc chloride as a second component.
3. A process as claimed in claim 1, wherein vegetable fibers are carbonized in the presence of at least one member selected from the group consisting of nitric acid, boric acid and an ammonium salt of an inorganic acid and the carbonized materials are then activated in the presence of zinc chloride.
4. A process as described in claim 3, wherein the carbon-ization temperature is at about 250 to 450°C.
5. A process as described in claim 1, 2 or 3, wherein the ammonium salt of inorganic acid is ammonium chloride.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP84231/1978 | 1978-07-10 | ||
| JP8423178A JPS5510473A (en) | 1978-07-10 | 1978-07-10 | Production of activated carbon fiber |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1151634A true CA1151634A (en) | 1983-08-09 |
Family
ID=13824694
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000331422A Expired CA1151634A (en) | 1978-07-10 | 1979-07-09 | Activated fibrous carbon |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS5510473A (en) |
| CA (1) | CA1151634A (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57191328A (en) * | 1981-05-13 | 1982-11-25 | Toho Rayon Co Ltd | Preparation of fibrous active carbon |
| JPS5818418A (en) * | 1981-07-21 | 1983-02-03 | Toyobo Co Ltd | Preparation of active carbon fiber |
| JPS58194026U (en) * | 1982-06-22 | 1983-12-23 | 横山綿業株式会社 | pine material |
| GB8422875D0 (en) * | 1984-09-11 | 1984-10-17 | Secr Defence | Fibrous activated carbon |
| JPH06104562B2 (en) * | 1985-07-24 | 1994-12-21 | 大阪瓦斯株式会社 | Activated carbon fiber manufacturing method |
| JPS62141126A (en) * | 1985-12-10 | 1987-06-24 | Agency Of Ind Science & Technol | Production of activated carbon fiber |
-
1978
- 1978-07-10 JP JP8423178A patent/JPS5510473A/en active Granted
-
1979
- 1979-07-09 CA CA000331422A patent/CA1151634A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5510473A (en) | 1980-01-24 |
| JPS6135284B2 (en) | 1986-08-12 |
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