KR100669490B1 - Process for surface modification of activated carbon - Google Patents

Abstract

A method for modifying the surface of an activated carbon is provided to increase the adsorption performance of the harmful substances included in the cigarette smoke. An active carbon is immersed into a treatment solution containing the nitric acid with a low concentration of 0.01-0.05M as an oxidizing agent or a treatment solution containing the nitric acid with a low concentration of 0.01-0.05M as an oxidizing agent and the sulfuric acid with a concentration of 0.001-1.0M as an inorganic acid. Thereafter, the active carbon is reacted at 50-100 degrees in centigrade for 1-72 hours. The reacted active carbon is washed by the distilled water and dried at 80-150 degrees in centigrade so that the functional group is introduced to the surface of the active carbon. Thereafter, the active carbon is oxidized at 300-500 degrees in centigrade for 0.5-4 hours so that the functional group is converted.

Description

Process for surface modification of activated carbon

The present invention relates to a surface modification method of activated carbon, and more particularly, harmful substances including vapor phase components such as hydrogen cyanide, acrolein, acetaldehyde, 1,3-butadiene among tobacco smoke components when used as an adsorbent of tobacco filters. It relates to a surface modification method for introducing a large amount of various functional groups on the surface of activated carbon in order to increase the adsorption capacity of.

Generally, activated carbon is widely used for the removal of harmful substances, and activated carbon made of coconut, wood, lignite, etc., is also used in tobacco filters to reduce harmful substances in cigarette smoke. Recently, due to the spread of social awareness about the harmfulness of tobacco, filter manufacturers and tobacco companies are conducting research to reduce gaseous components such as hydrogen cyanide and aldehydes in tobacco smoke.

Activated carbon used in cigarette filters generally has a large specific surface area consisting of micropores, which is advantageous for gas phase adsorption. Activated carbon produced by carbonizing coconut, wood, or lignite and then revitalizing with steam or chemicals is activated time and amount of steam input. Alternatively, specific surface area and pore size vary depending on the activating method of adding phosphoric acid, zinc chloride and the like and the basic characteristics of the raw material. The pores are generally composed of micropores of 2 nm or less and mesopores of 2 to 50 nm, and have a high nonpolar surface property, and thus have high adsorptive ability to benzene, naphthalene, etc., which are nonpolar materials, and have a high alkalinity of about 10 to 11 pH. Therefore, it is known that the adsorption characteristic of acid gas is excellent.

By raw materials, activated carbon produced by activating coconut has good adsorption capacity of small molecules or gaseous substances in tobacco smoke, and activated carbon made of wood or lignite has relatively high molecular weight. It is used for adsorption, waste water purification, and decolorization of sugar. It is also advantageous in removing large boiling point substances with large molecular size from tobacco smoke. However, since such activated carbon has a high pH, adsorption capacity of basic gas such as ammonia is greatly decreased.

Accordingly, filter manufacturers, tobacco manufacturers, and activated carbon manufacturers have proposed various methods of manufacturing activated carbon in order to increase the adsorption capacity of the activated carbon used in cigarettes and air purification, especially surface modifications in which metals or organic substances are attached to activated carbon. Efforts have been made to increase the adsorption capacity of harmful components and to selectively remove harmful components.

In this regard, US Pat. No. 6,789,547 discloses a technique which has a great effect on the removal of harmful substances in cigarette smoke by attaching alkali and transition metal materials to various activated carbons in various ways. However, this technology is difficult to use because the metal material itself is transferred to the human body in the smoking process and harmful to the human body.

In addition, US 6,595,218 discloses a technique for attaching 2-aminopropyl silane to silica gel and activated carbon, and silica gel or activated carbon prepared in this way has a high removal efficiency of HCN, aldehyde, etc. in tobacco smoke. There is this. In this technique, the impregnation of activated carbon was more efficient than that of silica gel. However, in the case of impregnation with activated carbon, the impregnated material blocks pores of the activated carbon, thereby lowering the overall efficiency of removing gaseous components.

In addition, Korean Patent Laid-Open Publication No. 1990-15652 discloses ene, citric acid, glycine, histidine and the like, which are compounds having high nucleophilic acidity and reacting with an aldehyde in an adsorbent such as activated carbon or zeolite to remove formaldehyde components in tobacco smoke. A technique for adding a synergistic composition consisting of a reagent having a diol functional group is disclosed. However, the addition of such compositions has the disadvantage that the composition deposited on the surface of the activated carbon can be transferred to the human body by particulate matter produced and carried out during the smoking process.

In addition, Korean Patent Laid-Open Publication No. 1999-16260 discloses hydrophilic effect by allowing oxygen in the air to react with the surface of the activated carbon by leaving the activated carbon made from various raw materials under the air atmosphere at 250 to 400 ° C. for 60 to 120 minutes. It has been disclosed a technique to increase the. In this case, the efficiency of activated carbon can be increased by reducing the amount of activated carbon suspended in the waste water during the purification of the wastewater.However, the activated carbon produced is lower than the sample treated with nitric acid, although the number of functional groups including oxygen increases. Since the use of activated carbon having a large particle size can reduce the amount of activated carbon suspended in water, there is a problem that does not significantly affect the removal ability of gaseous substances other than wastewater treatment.

As described above, when a substance such as a metal or an alkali metal is attached to the surface or pores of activated carbon, the substance adhered to the surface may be inhaled into the human body by an aerosol having a size of 0.1 to 1 μm constituting a smoke component, Even when trimethyl amine and the like, which are known to be highly reactive with hydrogen cyanide and aldehydes, are attached to tow or an adsorbent, the impregnated molecules may be transferred by the smoke constituents. Although they block the pores of activated carbon, there is an effect of the impregnated material, but there is a disadvantage that the physical adsorption effect is reduced by reducing the specific surface area.

In order to compensate for these disadvantages, methods of modifying the surface of activated carbon with a strong acid, a strong base, microwave, or air, without impregnating metals or organic substances with activated carbon, are known. Among them, a method of treating activated carbon with a strong acid is widely known. . In the case of surface modification of activated carbon by treating with strong acid, high concentration of strong acid has been generally used because the concentration of strong acid does not introduce a large amount of functional groups on the surface of activated carbon, so that synergistic effect of adsorption of harmful substances is not high.

However, treatment of activated carbon with high concentrations of strong acids can cause problems in commercial manufacturing. In particular, the treatment of activated carbon with high concentration of nitric acid has the advantage of being very effective in developing the surface functional groups, but it is difficult to manufacture commercially because the working environment becomes very poor due to the generation of harmful nitrogen oxide (NOx) gas during the nitric acid treatment. The mainstream smoke produced in the process not only has a problem that the nitric oxide gas which is very harmful to the human body remaining in the pores of activated carbon can be carried out after nitric acid treatment, but also the specific surface area is decreased due to the high concentration of acid, thereby reducing the physical effective adsorption area. There is a problem. In addition, the acid-treated activated carbon has a large amount of surface functional groups but is not effective for removing gas phase components, and thus, it is widely used as a pretreatment method for uniformly dispersing metal particles or salts on the surface.

Due to the problem of acid treatment, a method of oxidizing the surface by treating activated carbon at a high temperature in an air atmosphere has been introduced. The oxidation treatment by air is a simple and fast method for surface modification of activated carbon, Since there are not more functional groups than the acid treated activated carbon, there is a disadvantage in that the effect is not high for removing harmful components in tobacco smoke.

Therefore, it should be possible to commercialize by searching for a method that can minimize the generation of harmful gases while performing acid treatment in the production of activated carbon to selectively remove harmful components in cigarette smoke without impregnating metals or organic substances. To minimize the decrease in surface area and pore size of activated carbon, the physical adsorption area and volume of tobacco smoke should be increased.In addition, functional groups with high reactivity with smoke particles are introduced to increase the adsorption capacity of harmful substances, and like activated carbon impregnated with organic substances. There is a need for a method of surface treatment of activated carbon in which smoking material desorbs and does not migrate into the smoke during smoking.

In response to these demands, the present inventors have found that hydrogen and trace carboxyl groups, carbonyl groups or phenols are bonded to carbon rings, the main atoms constituting activated carbon, in addition to specific surface areas and pore sizes that contribute to physical adsorption of tobacco smoke or gaseous substances in the air. After surface functional groups such as phenolic hydroxyl groups are increased by a predetermined process, reactivation thereof enables the surface functional groups to be diversified into lactones, carbonyls, carboxylic anhydrides, nitrogen groups, and the like. This will prevent the migration of impregnated substances and lower specific surface area of ordinary impregnated activated carbons, and will significantly increase the amount of surface functional groups compared to activated carbon prepared by microwave and simple air oxidation. Same specific surface by increasing reactivity with harmful gaseous substances in the smoke And find out that the pore size and pore volume in the can significantly improve the adsorption capacity of the gaseous component, thereby completing the present invention.

Therefore, the present invention is to modify the surface of the activated carbon by combining the acid treatment and the method of treatment at high temperature in the air atmosphere, while minimizing the generation of harmful gas during acid treatment to introduce the functional group, By minimizing the reduction of the surface area and pore size of activated carbon, it is possible to increase the physical adsorption area and volume of tobacco smoke.In particular, the amount of surface functional groups is significantly increased compared to the existing simple method of oxidizing the surface with air. The purpose of the present invention is to provide a surface treatment method of activated carbon which can improve the adsorption capacity of gaseous components by increasing the reactivity with harmful gaseous substances.

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In order to achieve the above object, the present invention provides a treatment solution containing nitric acid at a low concentration of 0.01 to 0.5M as an oxidant or a nitric acid at a low concentration of 0.01 to 0.5M as an oxidant and sulfuric acid as an inorganic acid. After immersing activated carbon in the treatment solution contained in the concentration of 0.01 ~ 1.0M and reacted for 1 to 72 hours at 50 ~ 100 ℃, washed with distilled water to pH 3 ~ 6 and dried to functional groups on the surface of the activated carbon Introducing a; Activated carbon, comprising the step of oxidizing the functional group introduced on the surface of the activated carbon by oxidizing 0.5 to 5 hours at 300 ~ 500 ℃ while supplying a gas containing at least 10% oxygen to the activated carbon introduced functional group It provides a method of surface modification.

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Hereinafter, the present invention will be described in more detail.

The surface modification method of activated carbon according to the present invention to increase the adsorption capacity is largely by reacting activated carbon in a treatment solution composed of an oxidizing agent or an oxidizing agent and an inorganic acid to introduce a functional group, and oxidizing by heat treatment while supplying an oxygen-containing gas to the activated carbon into which the functional group is introduced. It consists of two steps to diversify the functional group into a functional group having excellent adsorption capacity.

Here, the activated carbon used for surface modification may be made of coconut, wood, lignite, and the like, as well as those manufactured using various materials. Also, activated carbon prepared by a known steam or chemical revival method may be used. It may be used, or by removing the impurities and metal by treating the prepared activated carbon with hydrochloric acid or sodium chloride, it can be used in addition to the activated carbon produced by a variety of known methods can be used.

In order to perform surface modification using the known activated carbon as described above, a functional group is first introduced into the activated carbon. More specifically, after immersing activated carbon in a treatment solution containing an oxidizing agent or an oxidizing agent and an inorganic acid, and reacting for 1 to 72 hours at 50 ~ 100 ℃, washed with distilled water to a pH of 3 to 6 and dried to the surface of the activated carbon The functional group is introduced.

When treated with activated carbon, the carbon ring structure constituting activated carbon is broken by the interaction between the oxidizing agent and the inorganic acid and is oxidized, so that hydrogen and a large amount of carboxyl, carbonyl, phenolic hydroxyl group, phenolic hydroxyl group, Surface functional groups such as nitro groups will be increased. These functional groups are partially contained on the surface of activated carbon before acid treatment, but these functional groups increase when the acid treatment is performed.

In this case, the oxidizing agent in the treatment solution for treating activated carbon may be used by selecting at least one from nitric acid, manganese dioxide (MnO ₂ ), potassium permanganate (KMnO ₄ ), hydrogen peroxide (H ₂ O ₂ ), metaphosphoric acid (HPO ₃ ) or ozone. In addition, various known oxidizing agents can be used, in particular, nitric acid is preferably used. In addition, the inorganic acid may be used by selecting at least one of nitric acid, sulfuric acid or hydrochloric acid, and particularly preferably nitric acid or sulfuric acid. That is, the preferred treatment solution is made of nitric acid or of nitric acid and sulfuric acid.

Here, it is very important that the concentration of nitric acid is low at 0.01 to 0.5 M both in the case where the treatment solution is made of nitric acid or when the treatment solution is made of nitric acid and sulfuric acid. In general, the treatment of activated carbon with nitric acid increases the surface functional groups, but it is known that high concentrations of acid have been used for the development of the surface functional groups. The physical effective adsorption area is reduced, the working environment is very poor due to the generation of nitrates, which are toxic gases in the process of activated carbon treatment, and the use of the activated carbons as an adsorbent for tobacco filters has the disadvantage of transferring the nitrates to mainstream smoke. It is very important to use low concentrations of nitric acid for this purpose. However, if the concentration of nitric acid is too small, the introduction of the functional group is not sufficiently made, it is very important to treat using the appropriate concentration.

At this time, if the concentration of nitric acid is less than 0.01M introduced functional group has a problem that the adsorption capacity of the smoke component is lowered, if the concentration of nitric acid is more than 0.5M introduced functional group is increased but the specific surface area decreases physical Since there is a problem that the adsorption capacity decreases, it is preferable to make the nitric acid in the treatment liquid a low concentration of 0.01 to 0.5M.

In addition, when the treatment solution consists of nitric acid and sulfuric acid, the concentration of sulfuric acid is sufficient to be 0.01 ~ 1.0M. At this time, when the concentration of sulfuric acid is less than 0.01M, the reactivity with the surface of nitric acid and activated carbon is lowered, and thus the functional group generating effect is not improved compared to the case of treating nitric acid only. When the concentration of sulfuric acid is higher than 1.0M, the specific surface area of activated carbon is It is preferable to use sulfuric acid in the above range because the problem that the lowering occurs.

As described above, when the activated carbon is immersed in the treating solution comprising the oxidizing agent or the oxidizing agent and the inorganic acid, and then reacted at 50 to 100 ° C. for 1 to 72 hours, the surface functional groups of the activated carbon are increased by the interaction of the oxidizing agent and the inorganic acid. After the reaction is completed, the mixture is washed repeatedly with distilled water to have a pH of 3 to 6 and then dried. At this time, the drying may be carried out at 80 ~ 150 ℃ until there is no further weight loss in the drying for efficient drying.

In this case, the amount of nitrous oxide, which is a harmful gas, is not generated and the working environment is not deteriorated. Also, the reduction of specific surface area of the dried activated carbon is low, and the activated carbon is treated using a treatment solution containing low concentration of nitric acid. Because it was processed.

According to the present invention, when a functional group is introduced to the surface of activated carbon through the above treatment, the activated carbon is oxidized at 300 to 500 ° C. for 0.5 to 4 hours while supplying a gas containing at least 10% or more of oxygen to the surface of the activated carbon. The functional group is converted.

Through such a process, the functional groups introduced in the above-described acid treatment step are oxidized through oxygen and chemical bonding to be converted into functional groups containing various oxygen. In addition, the added oxygen chemically bonds to the carbon having the active surface of the activated carbon and generates functional groups including various oxygen. Therefore, the heat treatment while supplying the gas containing oxygen can be made as well as diversification of the functional group, and thus the functional group is produced much more than the conventional method of oxidizing by heat treatment in the presence of oxygen activated carbon and has excellent adsorption capacity.

In this case, the gas may have a sufficient effect by containing only at least 10% oxygen, the gas other than 10% of the oxygen may be made of nitrogen, helium or carbon dioxide, etc., which is selectively made as necessary In addition, sufficient effect can be obtained by treating with air.

In addition, the heat treatment temperature is carried out at 300 ~ 500 ℃, if the heat treatment temperature is less than 300 ℃ there is a problem that the oxidation reaction is slow and the amount of functional groups generated is small, when the heat treatment temperature exceeds 500 ℃ activated carbon by oxygen It is good to heat-treat within the said range since there exists a problem of being a ash. Heat treatment of the activated carbon may be carried out in a known rotary kiln or fluidized bed reactor, and other known means may be used if necessary.

The surface-modified activated carbon thus subjected to oxidation treatment has a pore volume of 0.1 cm 3 / g or more provided by pores having a specific surface area of 500 to 3500 m 2 / g and a pore size of 0.3 to 1000 nm, and in particular, various functional groups on the surface. It can be very useful for adsorption of harmful substances.

Such surface-modified activated carbon has a lower surface area and pore size than the conventional heat treatment under oxygen atmosphere alone or slightly acid treatment. Is derived and shows very good results in the adsorption capacity of gaseous materials. In particular, the activated carbon surface-modified according to the present invention has a higher adsorption capacity of gaseous components by 50% or more even in the case of having a lower specific surface area than the activated carbon surface-treated and acid-treated activated carbon under an oxygen atmosphere. As a result, the present invention is excellent in adsorption capacity by heat treatment in a continuous oxygen atmosphere even in the case of low concentration acid treatment, it is possible to obtain a surface-modified activated carbon.

Therefore, the surface-modified activated carbon according to the present invention can be widely used for the purpose of adsorbing gaseous harmful substances, including cigarette filters. In particular, when the surface-modified activated carbon is added to the tobacco filter as an adsorbent, the adsorption capacity of gaseous components such as aldehydes and organic volatile substances (VOC) in tobacco smoke is very high. This is because a large amount of functional groups having excellent adsorption capacity exists on the surface of the activated carbon surface-modified by the present invention.

Here, the cigarette filter is made of a filter member such as acetate tow or paper according to a known method, and may have a filter having various structures in addition to the usual double filter or triple filter using an adsorbent. However, in the present invention, when the surface-modified activated carbon according to the present invention is used as an adsorbent in the production of known double filters and triple filters, it exhibits excellent adsorption of harmful substances.

At this time, in the manufacturing process of the known tobacco filter, the filter is selected from triacetin, triethylene glycol diacetate, dibutyl phthalate, dimethoxyethyl phthalate, etc. in order to maintain the predetermined hardness and to facilitate the connection with citrus herb. The plasticizer is to be added, but when using the activated carbon according to the present invention, it is preferable not to use the plasticizer or to use 2% or less. As such, when calcining is used at 2% or less, it is possible to exhibit more excellent removal efficiency by preventing the degradation of reactivity of the activated carbon surface functional group and the blocking of pores.

Tobacco using the tobacco filter thus prepared contains vapor-based components such as hydrogen cyanide, acrolein, acetaldehyde, and 1,3-butadiene, which are known to be harmful substances contained in the mainstream smoke during the smoking process, as described above. Can be significantly reduced.

Hereinafter, the present invention will be described in more detail with reference to the following examples, which are presented to aid the understanding of the present invention, but the present invention is not limited thereto.

<Example 1>

In the nitric acid solution of which the concentration of nitric acid was adjusted to 0.2 M, the coconut shell raw material was reacted for 5 hours at 70 ° C. while immersing 15 to 80 mesh activated carbon prepared by a well-known steam activating method, and then washed with distilled water. It was confirmed that the pH of 6, it was dried at 100 ℃. The dried activated carbon was oxidized at 410 ° C. for 2 hours while injecting air from a rotary kiln to obtain surface modified activated carbon.

<Example 2>

Except that the concentration of nitric acid was adjusted to 0.05M in the same manner as in Example 1 to obtain a surface-modified activated carbon.

<Example 3>

Except for adjusting the concentration of nitric acid to 0.5M was carried out in the same manner as in Example 1 to obtain a surface-modified activated carbon.

Comparative Example 1

Except that the concentration of nitric acid was adjusted to 0.005M in the same manner as in Example 1 to obtain a surface-modified activated carbon.

Comparative Example 2

Except that the concentration of nitric acid was adjusted to 1.0M in the same manner as in Example 1 to obtain a surface-modified activated carbon.

Comparative Example 3

In the nitric acid solution of which the concentration of nitric acid was adjusted to 0.2 M, the coconut shell raw material was reacted for 5 hours at 70 ° C. while immersing 15 to 80 mesh activated carbon prepared by a well-known steam activating method, and then washed with distilled water. It was confirmed that the pH of 6, it was dried at 100 ℃ to obtain a surface-modified activated carbon.

<Comparative Example 4>

Coconut shell material was oxidized at 15 to 80 mesh activated carbon prepared by a known steam activating method at 410 ° C. for 2 hours while injecting air into a fluidized bed reactor to obtain surface modified activated carbon.

Experimental Example 1

Measurement of surface area and pore size and average pore size of the activated carbon prepared in Examples 1 to 3 and Comparative Examples 1 to 4, and activated carbon (control 1) prepared by steam activating coconut shell raw materials (BET, N ₂ adsorption method) and the results are shown in Table 1 below.

division Specific surface area analysis (㎡ / g) Pore volume Average pore size Specific surface area Micropore area External surface area (cc / g) (Å) Example 1 1395 1019 377 0.413 17.50 Example 2 1456 1097 359 0.427 17.60 Example 3 1382 1012 370 0.420 17.10 Comparative Example 1 1466 1034 432 0.418 17.20 Comparative Example 2 1343 998 345 0.402 17.70 Comparative Example 3 1376 1045 351 0.423 17.17 Comparative Example 4 1410 1040 370 0.423 17.48 Control 1 1484 984 500 0.393 17.18

As shown in Table 1, in Examples 1 to 3, Comparative Example 1 and Comparative Example 2 carried out while changing the concentration of nitric acid, it can be seen that the specific surface area decreases as the concentration of nitric acid is generally higher, in particular, the concentration of nitric acid. In Comparative Example 1 and Comparative Example 2, which is outside the scope of the present invention, Comparative Example 2 having a high concentration of nitric acid can be seen that the specific surface area is greatly reduced. Comparative Example 3 and Comparative Example 4 correspond to the case where only a low concentration of acid treatment and only heat treatment under an air atmosphere, respectively, in Comparative Example 3 it can be seen that the specific surface area characteristics are slightly reduced compared to Comparative Example 4. .

Experimental Example 2

In order to grasp the functional group content of the activated carbon prepared in Examples 1 to 3 and Comparative Examples 1 to 4, and activated carbon (control 1) prepared by the steam regeneration method, the elemental analysis was performed and the results are shown in the following table. 2 is shown.

division Elemental content (%) N C H O Example 1 0.29 92.0 0.23 7.48 Example 2 0.27 92.9 0.22 6.61 Example 3 0.41 91.4 0.24 7.95 Comparative Example 1 0.29 93.9 0.23 5.58 Comparative Example 2 0.49 90.9 0.39 8.22 Comparative Example 3 0.43 91.4 0.47 7.70 Comparative Example 4 0.25 93.1 0.22 6.43 Control 1 0.27 94.3 0.22 5.21

As shown in Table 2, the functional groups (nitrogen, hydrogen and oxygen except carbon) of Examples 1 to 3, Comparative Example 1 and Comparative Example 2, which used nitric acid as an oxidizing agent in the acid treatment for surface modification of activated carbon as shown in Table 2 above. It can be seen that the content increases as the concentration of nitric acid increases. In Comparative Example 2 having the highest concentration of nitric acid, it can be seen that the functional group content is very high. As shown in Table 1, there is a problem in that the specific surface area is reduced. It can be confirmed that the content of the functional group is lower in Comparative Example 3, which performed only low concentration acid treatment, and Comparative Example 4, which performed heat treatment only under an air atmosphere, as compared with Examples 1 to 3.

Experimental Example 3

Activated carbons prepared in Examples 1 to 3 and Comparative Examples 1 to 4 and activated carbons (control 1) prepared by steam quenching of coconut shell raw materials, respectively, in the direction of each grass in the known double filter structure (acetate double filter). Tobacco was added to the tow to prepare a cigarette filter, and the tobacco filter thus prepared was connected to the tobacco to produce tobacco. The smoke component analysis in the mainstream smoke of the tobacco thus prepared was analyzed as follows based on ISO and KOLAS standard analysis methods, and the results are shown in Tables 3 to 7, respectively. In this case, the reduction rate in each result is shown in comparison with Control 1.

In Table 3, 20 cigarettes were harmonized for 48 hours at 22 ± 1 ° C and 60 ± 2% thermohygrostat, and then under the conditions of ISO 4387/1000 (E) using a tobacco smoking device (RM20CS, Heinr Borgwaldt Co.). Smoke smoke condensate obtained by smoking at 1 puff / min, puff time of 2 seconds and 35 ml per puff was collected by Cambridge filter, extracted with 2-Propanol, and the amount of tar, nicotine and CO in the smoke component was measured by GC (Gas It was shown by analysis by chromatography, Waters, Alliance 2695 separation module method.

 In Table 4, after mixing two cigarettes in the same manner as above, the carbonyl component produced while smoking under the conditions of ISO 4387 / 1000E was collected in an acetonitrile solution containing 2,4-DNPH (2,4-dinitrophenylhydrazine) derivative. The results were analyzed using HPLC (High Performance Liquid Chromatography).

In Table 5, the organic volatile components (VOCs) generated while smoking the five cigarettes prepared under ISO 4387 / 1000E were collected in 20 mL of a methanol solution containing 200 μl of an internal standard solution, followed by gas chromatography-mass spectrometry. The results were analyzed using Mass spectrometry (Agilent Technologies, 6890N Network GC system).

Table 6 The five cigarettes prepared above were collected by smoking under the conditions of ISO 4387 / 1000E and collected in a 30 mL aqueous solution containing 0.1 M malic acid, followed by ion exchange chromatography (Ion chromatography Cionex Corp. Dionex DX-500 ion chromatography). The result of analysis using and smoking the prepared five cigarettes under the condition of ISO 4387 / 1000E was collected by connecting a trap containing 50ml of methanol to Duba Frask with dry ice-acetone in duplicate. After UV The analysis results using the Spctrophotometer were included.

Table 7 captures 5 cigarettes under the conditions of ISO 4387 / 1000E, collects phenol components in 1% (w / w) acetic acid solution, and then uses HPLC (High Performance Liquid Chromatography, Waters, Alliance 2695 separation module). The analysis results are shown.

General smoke content shift division Tar (mg / cig.) Nicotine (mg / cig.) CO (mg / cig.) Example 1 5.5 0.49 6.4 Example 2 5.3 0.48 6.2 Example 3 5.2 0.48 5.8 Comparative Example 1 5.8 0.52 6.3 Comparative Example 2 5.8 0.55 6.2 Comparative Example 3 5.5 0.50 6.6 Comparative Example 4 5.3 0.50 6.1 Control 1 5.4 0.52 6.2

Carbonyl content amount and total reduction rate (μg / cig.) division Form- aldehyde Acet-aldehyde Acetone Acrolein Propion-aldehyde Croton- aldehyde M.E.K Butyr- aldehyde Total Reduction Rate (%) Example 1 6.26 55.89 36.55 0.00 2.34 1.19 1.78 1.47 105.5 75.8 Example 2 7.3 108.8 67.3 3.2 6.0 5.7 10.7 6.5 215.5 50.5 Example 3 7.03 65.3 34.85 3.8 5.2 6.23 6.8 6.5 135.7 68.8 Comparative Example 1 8.8 142.6 129.2 16.7 12.8 6.2 15.3 8.2 339.8 21.9 Comparative Example 2 10.7 194.5 162.5 25.1 19.7 9.6 23.9 12.3 458.3 -5.3 Comparative Example 3 11.2 244.8 191.8 25.5 21.5 10.1 25.6 13.6 544.2 -25.0 Comparative Example 4 7.1 154.7 121.2 16.1 13.6 6.4 16.2 8.6 343.9 21.0 Control 1 9.0 195.9 153.5 20.4 17.2 8.1 20.5 10.9 435.3 0.0

Organic Volatile Substances (VOCs) Transfer and Total Decrease (μg / cig.) division 1.3-butadiene Acrylonitrile Isoprene Benzene Toluene Total % Reduction Example 1 5.5 4.5 31.6 2.7 2.7 47.0 77.0 Example 2 10.2 7.8 57.2 9.8 10.6 95.6 53.3 Example 3 5.8 4.1 45.4 2.5 4.5 62.3 69.6 Comparative Example 1 19.9 7.9 95.0 15.5 17.4 155.7 23.9 Comparative Example 2 25.2 13.1 136.2 18.7 26.1 219.3 -7.2 Comparative Example 3 28.7 13.9 148.9 24.4 28.3 244.2 -19 Comparative Example 4 17.1 8.4 97.8 13.2 17.9 154.4 24.6 Control 1 23.7 12.9 124.5 19.3 24.3 204.7 0.0

HCN and Ammonia migration and overall reduction (μg / cig.) division HCN ammonia HCN reduction rate Ammonia reduction rate Example 1 6.0 4.1 81.2 44.0 Example 2 16.8 5.1 47.4 30.5 Example 3 9.2 4.3 71.4 41.1 Comparative Example 1 25.0 5.3 21.9 27.8 Comparative Example 2 33.7 5.9 -5.3 20.3 Comparative Example 3 38.0 9.6 -18.7 -30.8 Comparative Example 4 22.3 5.8 30.4 21.1 Control 1 32.0 7.3 0.0 0.0

Phenol Content Transfer and Total Reduction (μg / cig.) division Hydroquinone Resorcinol Catechol Phenol m + p Cresol o-Cresol Total % Reduction Example 1 25.272 0.849 36.796 5.545 4.624 1.375 74.461 18.20 Example 2 27.310 0.900 37.770 6.070 5.000 1.550 78.600 13.65 Example 3 25.620 0.820 37.190 5.620 4.800 1.470 75.520 17.04 Comparative Example 1 27.650 0.890 40.150 6.550 5.530 2.450 83.220 8.58 Comparative Example 2 31.031 1.376 48.433 10.972 6.184 2.923 100.919 -10.86 Comparative Example 3 31.496 1.212 52.685 10.562 7.273 3.411 106.639 -17.15 Comparative Example 4 28.040 0.960 39.060 6.180 4.860 1.530 80.630 11.42 Control 1 30.100 0.990 41.080 9.390 6.830 2.640 91.030 0.00

As shown in Tables 3 to 7, as a result of measuring the smoke component transition amount of the tobacco produced using the tobacco filter prepared according to the present invention, the concentration of nitric acid in the preferred concentration range of the present invention when nitric acid was used as the oxidant In the case of Examples 1 to 3 heat treated under an air atmosphere after acid treatment, compared to Comparative Example 1 and Comparative Example 2, which were heat treated under an air atmosphere after acid treatment in a state in which the concentration range of nitric acid was outside the range of the present invention. It can be seen that it shows an excellent adsorption performance.

In addition, in the case of Examples 1 to 3 it can be seen that shows a significantly improved adsorption performance compared to the control 1 using the conventional general activated carbon. In particular, in the case of Comparative Example 3, which performed only low concentration acid treatment, and Comparative Example 4, which performed heat treatment only in an air atmosphere, the combination of these results appeared to be similar to or lower than that of the control, according to the present invention. It can be seen that Examples 1 to 3, which were simultaneously subjected to heat treatment under an air atmosphere, showed much improved results, and in the case of aldehyde and organic vapor phase components, the removal rate was increased by about 50% or more.

In addition, in the case of Comparative Example 4 subjected to heat treatment only with air, it can be seen that although the specific surface area is higher than that of Example 1, as shown in Table 1, the adsorption performance is greatly reduced. This is because when the activated carbon is treated according to the present invention as shown in Table 2, the amount of functional groups increases, and the adsorption performance of the introduced functional groups becomes excellent.

<Example 4>

The surface-modified activated carbon was prepared in the same manner as in Example 1, except that a mixed acid aqueous solution having a nitric acid concentration of 0.2 M and a sulfuric acid concentration of 0.5 M was used instead of an aqueous nitric acid solution having the concentration of nitric acid adjusted to 0.2 M. Got it.

Example 5

The surface-modified activated carbon was obtained by the same method as Example 4 except that the concentration of sulfuric acid was adjusted to 0.05 M in the mixed acid aqueous solution.

<Example 6>

Except that the concentration of sulfuric acid in the mixed acid aqueous solution was adjusted to 1.0M in the same manner as in Example 4 to obtain a surface-modified activated carbon.

Comparative Example 5

The surface-modified activated carbon was obtained by the same method as Example 4 except that the concentration of sulfuric acid in the mixed acid aqueous solution was adjusted to 0.005M.

Comparative Example 6

A surface-modified activated carbon was obtained in the same manner as in Example 4 except that the concentration of sulfuric acid in the mixed acid aqueous solution was adjusted to 2.0 M.

Experimental Example 4

Measurement of surface area and pore volume and average pore size of the activated carbon prepared in Examples 4 to 6 and Comparative Examples 5 and 6 and activated carbon prepared by palm steam raw material (control 1) (BET, N ₂₎ Adsorption method) and the results are shown in Table 8 below.

division Specific surface area analysis (㎡ / g) Pore volume Average pore size Specific surface area Micropore area External surface area (cc / g) (Å) Example 4 1358 1020 338 0.406 17.40 Example 5 1389 1023 366 0.417 17.50 Example 6 1335 992 333 0.412 17.60 Comparative Example 5 1402 1016 386 0.421 17.40 Comparative Example 6 1271 835 436 0.400 17.50 Control 1 1484 984 500 0.393 17.18

As shown in Table 8, in the case of Examples 4 to 6, Comparative Example 5 and Comparative Example 6 using a mixed acid of sulfuric acid nitrate during acid treatment, it can be seen that the specific surface area decreases as the concentration of sulfuric acid is higher. In the case of Comparative Example 6, which has the highest concentration, it can be seen that the specific surface area is significantly reduced. In this case, it can be seen that the specific surface area is slightly reduced as compared with the specific surface areas of Examples 1 to 3 (see Table 1) using only nitric acid during acid treatment.

Control Table 1 in Table 8 shows the surface area analysis and the pore volume and the average pore size of Control 1 shown in Table 1 above to facilitate the comparative analysis of the results. The results of Control 1 are shown together to facilitate this.

Experimental Example 5

To analyze the functional group content of the activated carbon prepared in Examples 4 to 6, Comparative Examples 5 and 6, and activated carbon (control 1) prepared by the steam regeneration method, the elemental analysis was performed and the results are shown in the following table. 9 is shown.

division Elemental content (%) N C H O Example 4 0.37 90.7 0.22 8.71 Example 5 0.38 91.1 0.23 8.29 Example 6 0.33 90.5 0.21 8.96 Comparative Example 5 0.30 91.7 0.22 7.78 Comparative Example 6 0.63 90.3 0.39 8.68 Control 1 0.27 94.3 0.22 5.21

As shown in Table 9 above, when nitric acid is used as an oxidizing agent and sulfuric acid is used as an oxidizing agent for acid treatment for activated carbon, the content of functional groups (nitrogen, hydrogen and oxygen except carbon) increases as the concentration of sulfuric acid increases. Can be. In the case of Comparative Example 6 having the highest concentration of sulfuric acid, it can be seen that the functional group content is very high. As shown in Table 8, the specific surface area has a problem of decreasing. At this time, when comparing the functional groups of Examples 4 to 6 with the functional groups of Examples 1 to 3 (see Table 2) using only nitric acid during acid treatment, it can be confirmed that the functional groups increase as a whole.

Experimental Example 6

Activated carbon prepared in Examples 4 to 6, Comparative Examples 5 and 6, and activated carbon (control 1) prepared by steam activating coconut shell raw materials, respectively, in the direction of each grass in the known double filter structure (acetate double filter). Tobacco was added to the tow to prepare a cigarette filter, and the tobacco filter thus prepared was connected to the tobacco to produce tobacco. The smoke component analysis in the mainstream smoke of the tobacco thus prepared was performed in the same manner as in Experiment 3, and the results are shown in Tables 10 to 14, respectively.

General smoke content division Tar (mg / cig.) Nicotine (mg / cig.) CO (mg / cig.) Example 4 5.4 0.51 6.2 Example 5 5.7 0.55 6.4 Example 6 5.6 0.54 6.6 Comparative Example 5 5.9 0.49 6.5 Comparative Example 6 5.8 0.52 6.7 Control 1 5.4 0.52 6.5

Carbonyl content amount and total reduction rate (μg / cig.) division Form- aldehyde Acet-aldehyde Acetone Acrolein Propion-aldehyde Croton- aldehyde M.E.K Butyr- aldehyde Total Reduction Rate (%) Example 4 5.26 25.01 12.55 0.00 1.34 1.12 1.78 1.20 48.2 88.9 Example 5 6.12 31.89 15.75 0.00 1.94 2.12 2.18 1.12 61.1 86.0 Example 6 6.3 46.2 19.9 0.0 2.2 1.0 2.7 1.4 79.8 81.7 Comparative Example 5 6.66 48.89 38.55 0.00 1.93 2.24 1.59 1.53 101.4 76.7 Comparative Example 6 10.0 209.3 161.9 22.9 19.2 9.0 23.0 12.2 467.5 -7.4 Control 1 9.0 195.9 153.5 20.4 17.2 8.1 20.5 10.9 435.3 0.0

Organic Volatile Substances (VOCs) Transfer and Total Decrease (μg / cig.) division 1.3-butadiene Acrylonitrile Isoprene Benzene Toluene Total % Reduction Example 4 3.3 2.9 6.4 1.3 1.3 15.4 92.5 Example 5 4.9 3.0 10.5 2.1 2.2 22.8 88.9 Example 6 5.2 3.6 18.4 2.2 2.3 31.8 84.4 Comparative Example 5 6.6 4.7 34.2 2.7 3.1 51.4 74.9 Comparative Example 6 22.5 11.7 135.2 20.1 28.8 218.3 -6.7 Control 1 23.7 12.9 124.5 19.3 24.3 204.7 0.0

HCN and Ammonia migration and overall reduction (μg / cig.) division HCN ammonia HCN reduction rate Ammonia reduction rate Example 4 2.6 2.5 91.9 65.8 Example 5 4.2 2.6 86.9 64.3 Example 6 5.2 2.8 83.9 62.5 Comparative Example 5 6.3 4.3 80.1 41.1 Comparative Example 6 32.3 7.6 -1.1 -3.8 Control 1 32.0 7.3 0.0 0.0

Phenol Content Transfer and Total Reduction (μg / cig.) division Hydroquinone Resorcinol Catechol Phenol m + p Cresol o-Cresol Total % Reduction Example 4 23.540 0.820 35.000 4.640 3.920 1.120 69.040 24.16 Example 5 24.330 0.800 35.950 4.430 3.820 1.120 70.450 22.61 Example 6 24.490 0.820 36.590 5.710 4.530 1.500 73.640 19.10 Comparative Example 5 25.270 0.850 37.800 5.540 4.630 1.370 75.460 17.10 Comparative Example 6 27.680 0.890 38.570 8.100 6.030 2.160 83.430 8.35 Control 1 30.100 0.990 41.080 9.390 6.830 2.640 91.030 0.00

As shown in Tables 10 to 14, when the smoke component transition amount of the tobacco manufactured using the tobacco filter prepared according to the present invention was measured, a mixed acid of nitric acid and sulfuric acid was used as the activated carbon treatment solution. Examples 4 to 6, which were heat treated under an air atmosphere after acid treatment in the concentration range of sulfuric acid, had excellent adsorption compared to Comparative Examples 5 and 6, which were heat treated under an air atmosphere after acid treatment in a condition that the sulfuric acid concentration was outside the concentration range. You can see that it shows performance.

In particular, in Examples 1 to 3 it can be seen that shows a significantly improved absorption performance compared to the control 1 using the conventional general activated carbon, in the case of aldehydes and organic vapor phase components can be confirmed that the removal rate is increased by about 70% or more. have.

At this time, the smoke component of the tobacco produced using the tobacco filter prepared in Examples 4 to 6 and the smoke component of the tobacco manufactured using the tobacco filter prepared in Examples 1 to 3 using only nitric acid during acid treatment Comparing with the transfer amount (Tables 3 to 7), it can be seen that the absorption performance effect increased as a whole. Therefore, it can be seen that the use of nitric acid at low concentration as an oxidant and the use of sulfuric acid as an inorganic acid at the acid treatment show superior effects compared to the treatment using only low concentration of nitric acid.

<Example 7>

The surface-modified activated carbon was obtained in the same manner as in Example 1, except that 15-80 mesh activated carbon prepared by the chemical activation method was used instead of the steam activation method.

Comparative Example 7

A surface-modified activated carbon was obtained in the same manner as in Comparative Example 3, except that 15-80 mesh activated carbon prepared by the chemical activation method was used.

<Comparative Example 8>

A surface-modified activated carbon was obtained in the same manner as in Comparative Example 4, except that 15-80 mesh of activated carbon prepared by the chemical activation method was used.

Experimental Example 7

Surface area analysis and pore volume and average pore size of the activated carbon prepared in Example 7, Comparative Example 7 and Comparative Example 8, and activated carbon (control control 2) prepared by coconut shell raw material by chemical activation method (BET, N ₂ adsorption method) and the results are shown in Table 15 below.

division Specific surface area analysis (㎡ / g) Pore volume Average pore size Specific surface area Micropore area External surface area (cc / g) (Å) Example 7 1399 490 909 0.208 24.08 Comparative Example 7 1325 434 891 0.219 23.63 Comparative Example 8 1306 394 912 0.205 24.08 Control 2 1537 314 1243 0.192 25.82

In Table 15, Example 7 is a surface modified by heat treatment in an air atmosphere after the acid treatment using the activated carbon prepared by the chemical revival method, not activated carbon prepared by the steam regeneration method, Comparative Example 7 is compared with the case of the acid treatment only, Example 8 corresponds to the case where only heat treatment with air is performed. Comparative Example 7 and Comparative Example 8 show a lower specific surface area than Example 7.

Experimental Example 8

In order to grasp the functional group content of the activated carbon prepared in Example 7, Comparative Example 7 and Comparative Example 8, and activated carbon (control control 2) produced by the coconut shell raw material by the chemical revitalization method, the elemental analysis was performed and the results are as follows. Table 16 shows.

division Elemental content (%) N C H O Example 7 0.18 91.5 0.24 8.08 Comparative Example 7 0.29 91.6 0.35 7.76 Comparative Example 8 0.16 92.4 0.23 7.21 Control 2 0.16 93.8 0.24 5.80

As shown in Table 16, in the case of Example 7 heat treated under an air atmosphere after acid treatment using activated carbon prepared by chemical reactivation, the functional group was compared with Comparative Example 7 subjected to acid treatment only and Comparative Example 8 subjected to air treatment only. It can be confirmed that the content of (nitrogen, hydrogen and oxygen except carbon) is high.

Experimental Example 9

Activated carbon prepared in Example 7, Comparative Example 7 and Comparative Example 8, and activated carbon (Control 2) manufactured by the method of chemical activation of coconut shell raw material, respectively, in the direction of each grass in the known double filter structure (acetate double filter) Tobacco was added to the tow to prepare a cigarette filter, and the tobacco filter thus prepared was connected to the tobacco to produce tobacco. The smoke component analysis in the mainstream smoke of the tobacco thus prepared was performed in the same manner as in Experiment 3, and the results are shown in Tables 17 to 21, respectively.

General smoke content division Tar (mg / cig.) Nicotine (mg / cig.) CO (mg / cig.) Example 7 5.6 0.49 6.2 Comparative Example 7 5.3 0.47 6.1 Comparative Example 8 5.5 0.48 6.3 Control 2 5.6 0.54 6.0

Carbonyl content amount and total reduction rate (μg / cig.) division Form- aldehyde Acet-aldehyde Acetone Acrolein Propion-aldehyde Croton- aldehyde M.E.K Butyr- aldehyde Total Reduction Rate (%) Example 7 13.8 102.9 78.3 10.4 8.8 4.1 10.5 5.6 234.2 61.5 Comparative Example 7 16.9 326.5 263.2 31.7 25.3 10.3 23.2 15.3 712.4 -17.1 Comparative Example 8 15.8 218.5 158.2 12.9 10.8 5.1 12.9 6.9 441.0 27.5 Control 2 14.7 277.7 208.3 32.2 22.5 11.9 26.9 14.2 608.4 0.0

Organic Volatile Substances (VOCs) Transfer and Total Decrease (μg / cig.) division 1.3-butadiene Acrylonitrile Isoprene Benzene Toluene Total % Reduction Example 7 11.8 7.1 55.4 7.5 12.5 94.3 65.4 Comparative Example 7 32.1 21.2 189.2 26.2 35.2 303.9 -11 Comparative Example 8 19.8 12.9 122.3 16.5 19.5 191.0 30.0 Control 2 31.4 17.2 168.6 23.7 31.8 272.7 0.0

HCN and Ammonia migration and overall reduction (μg / cig.) division HCN ammonia HCN reduction rate Ammonia reduction rate Example 7 16.3 4.9 61.7 26.4 Comparative Example 7 39.8 6.4 6.5 4.0 Comparative Example 8 33.2 5.9 22.1 11.8 Control 2 42.6 6.7 0.0 0.0

Phenol Content Transfer and Total Reduction (μg / cig.) division Hydroquinone Resorcinol Catechol Phenol m + p Cresol o-Cresol Total % Reduction Example 7 10.483 0.638 18.802 4.821 3.498 1.729 39.971 55.21 Comparative Example 7 33.728 1.037 44.2528 10.043 5.792 3.559 98.412 -10.28 Comparative Example 8 22.549 0.845 37.636 8.892 5.627 2.128 77.677 12.96 Control 2 29.329 0.955 40.524 9.059 6.829 2.543 89.239 0.00

As shown in Tables 17 to 21, in Example 7, which was treated with acid treatment and air using activated carbon prepared by chemical reactivation as a raw material, Comparative Example 7 which was subjected to acid treatment only and Comparative Example 8 which was subjected to heat treatment only with air It can be seen that it shows a much improved adsorption performance compared to. In addition, in the case of Example 7, it can be seen that it shows a significantly improved adsorption performance compared to the control 2.

Even in the case of using activated carbon prepared by chemical reactivation, Comparative Example 7, which performed only low concentration acid treatment, and Comparative Example 8, which performed heat treatment only under an air atmosphere, showed similar results to those of the control, but in practically the present invention, As a result, Example 7, which was subjected to heat treatment under acid treatment and air atmosphere at the same time, showed much better results than the control. Therefore, if the acid treatment and heat treatment are performed simultaneously with air according to the present invention regardless of the raw material, it is possible to obtain the effect of improving the adsorption performance.

In addition, when compared to Example 1 using activated carbon produced by the steam activating method as a raw material, the fine pores were low, so the adsorption capacity for HCN, aldehydes and organic vapor phase materials was low, but the volatility was high. The removal ability of the large Phenol components was found to be high. This is because activated carbon produced by the chemical revival method has a lot of 2 ~ 50nm sized mesopores are developed rather than micropores, it is advantageous to the adsorption of large molecules, especially the surface effect is shown to increase the superiority.

As described above, the present invention introduces a variety of surface functional groups bound to carbon rings, which are the main atoms constituting activated carbon, in addition to specific surface area and pore size that contribute to physical adsorption of tobacco smoke or gaseous substances in the air. By preventing the migration of impregnated substances and lowering specific surface area of ordinary impregnated activated carbon, it increases the amount of surface functional groups compared to activated carbon prepared by microwave and simple air oxidation, which is harmful to tobacco smoke. The high reactivity with gaseous materials has a useful effect of providing a surface treatment method of activated carbon with the same specific surface area, pore size, and pore volume.

Claims (13)

In the surface modification method of activated carbon, After immersing activated carbon in a treating solution containing a low concentration of 0.01 to 0.5 M as an oxidizing agent or a treating solution containing a low concentration of 0.01 to 0.5 M as an oxidizing agent and a sulfuric acid containing a concentration of 0.01 to 1.0 M as an inorganic acid. Reaction was performed at 50 to 100 ° C. for 1 to 72 hours, washed with distilled water to a pH of 3 to 6, and then dried at 80 to 150 ° C. to introduce functional groups on the surface of activated carbon, and at least 10 to activated carbon into which the functional groups were introduced. A method of surface modification of activated carbon, characterized by converting functional groups introduced on the surface of activated carbon by oxidizing at 300 to 500 ° C. for 0.5 to 4 hours while supplying a gas containing at least oxygen. delete delete The method according to claim 1, Surface treatment method of activated carbon, characterized in that the treatment solution is contained in a low concentration of nitric acid 0.01 ~ 0.5M as an oxidizing agent. delete The method according to claim 1, The treatment solution is a surface modification method of activated carbon, characterized in that the nitric acid is contained in a low concentration of 0.01 to 0.5M as an oxidizing agent and sulfuric acid in a concentration of 0.01 to 1.0M as an inorganic acid. delete delete delete delete delete delete delete