JPH04200634A - Active carbon for deodorization - Google Patents

Abstract

PURPOSE:To obtain a deodorant having excellent in particular removing ability of basic gas by allowing a raw active carbon to react with sulfuric acid in the presence of acetic anhydride and fixedly and chemically combining with surface part of the active carbon. CONSTITUTION:The raw active carbon is allowed to react with sulfuric acid in the presence of acetic anhydride. At this time, sulfonic group as a functional group fixedly and chemically combines with end of active carbon molecule and the structure having the surface part of active carbon surrounded with sulfonic group is obtained. Then the sulfonic group does not eliminate in the use and does not fall out in the case of wet molding. The deodorant obtained in such a way has excellent removing ability of basic gas.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to deodorizing activated carbon, and more specifically,
The present invention relates to deodorizing activated carbon in which a sulfonic acid group as a functional group is fixedly bonded to a surface site. The activated carbon for deodorization of the present invention has excellent deodorizing performance, especially against basic malodorous components (for example, ammonia odor), and can maintain this performance for a long period of time. It can be used advantageously for the purpose.

[Conventional technology]

There are various deodorization methods such as chemical cleaning method, direct combustion method, catalytic oxidation method, biological deodorization method, and adsorption deodorization method, but the most commonly used method for boat fishing is adsorption deodorization using activated carbon. It is the law. This is because activated carbon adsorbs and removes a wide range of malodorous components. Unfortunately, however, this adsorption deodorization method has a low adsorption capacity for polar components (acidic/basic malodorous components) such as acetaldehyde and ammonia, and this point needs to be improved. Therefore, recently, impregnated activated carbon has come to be used to compensate for the drawback of low adsorption capacity for polar components.

As is well known, impregnated activated carbon is a salt of a metal such as copper, zinc, silver, or copper, or an acid (organic acid, etc.) such as phthalic acid or sulfuric acid.
An impregnant consisting of an inorganic acid is attached to the surface of activated carbon by physical means, and it has good adsorption ability for polar components. However, as mentioned above, these impregnated activated carbons have the impregnant attached to the surface of the activated carbon through physical adsorption, so they may come off during use, or the impregnant may fall off during wet molding, resulting in a significant drop in performance. There is a problem with that.

[Problem to be solved by the invention]

Therefore, an object of the present invention is to provide an improved deodorizing system that has excellent deodorizing performance, particularly against basic malodorous components such as ammonia odor, and that can stably maintain this performance over a long period of time. The purpose is to provide activated charcoal for use.

[Means to solve the problem]

As a result of intensive research to achieve the above object, the present inventors focused on the molecular structure of activated carbon (which is thought to correspond to an aromatic polycyclic compound in which aromatic rings are connected like a honeycomb), We found that it is effective to directly immobilize a sulfonic acid group for adsorbing basic odor components to the aromatic ring by chemical bonding, and completed the present invention as detailed below.

The present invention is characterized in that it is obtained by reacting raw material activated carbon and sulfuric acid in the presence of acetic anhydride, and has a sulfonic acid group fixedly chemically bonded to its surface site. There is activated carbon for deodorization.

[Function] As described above, the deodorizing activated carbon of the present invention is obtained by reacting raw material activated carbon and sulfuric acid in the presence of acetic anhydride. When sulfonation is carried out in this manner, the sulfonic acid group as a functional group is fixedly chemically bonded to the terminal end of the activated carbon molecule, resulting in a structure in which the surface portion of the activated carbon is surrounded by sulfonic acid groups. For example, this reaction formula is as follows (a part of the possible molecular structure of activated carbon is shown):Activated carbon
Activated Carbon Containing Immobilized Sulfonic Acid Groups The sulfonic acid groups (-5O3M) immobilized on the surface of activated carbon in this way do not come off during use or fall off during wet molding. In addition, while sulfuric acid-impregnated activated carbon for general basic odors loses its performance due to sulfuric acid being released when washed with water or left at high temperatures, the sulfonated activated carbon synthesized as described above has sulfonic acid groups chemically bonded to the activated carbon. Since it is immobilized by bonding, no deterioration in adsorption performance is observed at all. Furthermore, in the case of sulfuric acid-impregnated activated carbon, the sulfuric acid aggregates and does not work effectively, whereas in the case of sulfuric acid groups, the sulfonic acid groups are uniformly immobilized on the activated carbon surface.
The basic gas removal performance is extremely excellent. Furthermore, regarding the sustainability of adsorption performance, since the initial adsorption performance has already been significantly improved compared to conventional products, the period during which the adsorption performance loses the same level as conventional products will be longer. Sustainability also improves (see Figure 2).

Furthermore, in the conventional technique, sulfonic acid groups are introduced into activated carbon by treatment with only sulfuric acid, but the amount of sulfonic acid groups introduced by this method is small, and therefore the deodorizing effect is also small.

In contrast, in the present invention, sulfuric acid is added dropwise in the presence of acetic anhydride and the reaction is carried out under optimal temperature conditions, so the amount of sulfonic acid groups immobilized on the activated carbon surface is significantly increased. Therefore, the deodorizing efficiency is also extremely high. Here, one of the reasons why the reaction efficiency of sulfonation was improved by the presence of acetic anhydride is that when a cation intermediate is generated as a reaction intermediate, acetic anhydride as a solvent stabilizes the cation intermediate. The second reason is that acetic anhydride reacts with the generated water molecules, removes the water molecules, and promotes sulfonation. .

Incidentally, the ammonia adsorption characteristics of the immobilized sulfonic acid group-containing activated carbon, the sulfuric acid impregnated activated carbon, and the non-impregnated activated carbon according to the present invention are shown in graphs as shown in FIG. The initial concentration of ammonia is 200pp.
It was set to m. From this figure, the excellent ammonia adsorption properties of the activated carbon of the present invention can be understood.

[Example] The deodorizing activated carbon of the present invention can be prepared by treating raw material activated carbon with sulfuric acid in the presence of acetic anhydride.

As the raw material activated carbon, commercially available activated carbon such as activated carbon fibers, powdered or granular activated carbon, and others can be arbitrarily selected and used. Conditions such as the form, powder size, and particle size of the raw material activated carbon to be used can also be changed arbitrarily depending on the purpose of use.

Although the raw activated carbon can be treated with sulfuric acid according to various methods, it is preferable to mix the raw activated carbon and acetic anhydride and then gradually drop sulfuric acid into the resulting mixture. Concentrated sulfuric acid (concentration of about 98%) is preferable as the sulfuric acid, and use of dilute sulfuric acid diluted or sulfuric acid containing a large amount of water should be avoided since sulfonation will not proceed sufficiently. That is, the presence of water molecules in the sulfonation reaction system makes it extremely difficult for the reaction to occur. Although the amount of sulfuric acid added can be varied within a wide range, it is preferably about 60 sulfuric acid per 100 s of raw activated carbon.
% by weight or more. If the amount of sulfuric acid added is less than about 60% by weight, it will be difficult to achieve a removal rate of malodorous components (eg ammonia) of 90% or more. The temperature of this sulfuric acid treatment is preferably about 50 to 90°C, more preferably about 60 to 70°C.

An example of a preferred process for preparing the deodorizing activated carbon of the present invention is as follows: (1) Filling the raw material activated carbon into a reactor (2) Adding acetic anhydride (3) Reaction Raising the temperature of the contents of the vessel (60 to 70°C) and stirring (4) Adding concentrated sulfuric acid dropwise (with stirring) (5) Stirring (6) Cooling (7) Filtration (8) Washing with alcohol (9) Washing with water (to adjust the pH) Adjustment to neutrality) (10) Drying In this way, the activated carbon containing immobilized sulfonic acid groups according to the present invention is obtained.

The immobilized sulfonic acid group-containing activated carbon according to the present invention can be processed into various forms and used for deodorizing purposes and other purposes. For example, the activated carbon of the present invention can be made into paper and used as an element of an air purifier or deodorizing paper (shoji paper, sliding door paper, wrapping paper, etc.). Furthermore, the granular activated carbon can be used as a deodorizing agent for refrigerators, shoe cabinets, etc. by filling the container as is.

Hereinafter, the preparation of the immobilized sulfonic acid group-containing activated carbon according to the present invention and its excellent deodorizing performance will be explained in detail with reference to specific examples. The evaluation of ammonia adsorption performance was conducted using a batch method.
Fill with p- ammonia gas and place 0.5 of the sample into it.
g was added thereto, and the ammonia concentration was measured using an ammonia detection tube inside the container. The ammonia residual rate 30 minutes after the start of adsorption was determined from the measured ammonia concentration, and the ammonia removal rate was calculated from this ammonia residual rate.

200 g of activated carbon fibers were uniformly dispersed in acetic anhydride 1000 II 11, and concentrated sulfuric acid (98%) 90 was added dropwise at a rate of 3 d/min over a period of 30 minutes at a treatment temperature of 60-70°C. Thereafter, reaction treatment was carried out for 1 hour while stirring to complete the sulfonation. After the reaction was completed, the sulfonated activated carbon fibers were separated by filtration using a glass filter, washed with alcohol, and washed with water repeatedly until the PTT value became neutral. After drying the obtained activated carbon fiber containing immobilized sulfonic acid groups at 120°C, the ammonia adsorption performance was evaluated. The results obtained are shown in Table 1 below and the attached Figure 3.

Further, the sulfonic acid group content of the obtained immobilized sulfonic acid group-containing activated carbon fiber was measured by elemental analysis of sulfur, and was found to be 9.7 Xl0-' mol/g.

Incidentally, from the results of this example and other experiments conducted by the present inventors, in order to achieve an ammonia removal rate of 90% or more, the amount of sulfonic acid groups contained in the activated carbon of the present invention is 7. O
It is preferable that it is Xl0-'mol/g or more.

! Crude carbon 200 g of activated carbon (powder) was uniformly dispersed in 400 d of acetic anhydride, and the same treatment as in Example 1 was performed.

The ammonia adsorption performance of the obtained immobilized sulfonic acid group-containing activated carbon was evaluated in the same manner as in Example 1 above. The results obtained are shown in Table 1 below and the attached Figure 3.

In addition, when the sulfonic acid group content of the obtained immobilized sulfonic acid group-containing activated carbon was measured by elemental analysis of sulfur,
It was 10.6 x 10-' mol/g.

Furthermore, in order to evaluate the sustainability of the ammonia adsorption properties of the activated carbon of the present invention, the same adsorption performance evaluation was carried out three times and five times.
The test was repeated 3 times, 6 times, and 7 times, and the results are plotted in FIG. For comparison, the same operation was repeated for raw activated carbon (non-impregnated activated carbon).
The respective results are plotted in Figure 2. These results show that the activated carbon of the present invention not only has a markedly superior initial ammonia adsorption property, but also maintains it for a long time, and only after repeated use six times does it surpass the conventional activated carbon (non-impregnated activated carbon). It can be seen that the ammonia adsorption properties are almost the same as new products.

Kitadono Goko concentrated sulfuric acid (98%) 90 ae was added to 200 g of activated carbon, and reaction treatment was carried out at a treatment temperature of 60 to 70° C. for 3 hours to complete the sulfonation. After the reaction is completed, the sulfonated activated carbon is separated by filtration using a glass filter, and the pH is adjusted.
Washing with water was repeated until the value became neutral.

The ammonia adsorption performance of the obtained immobilized sulfonic acid-containing activated carbon was evaluated in the same manner as in Example 1 above.

The results obtained are shown in Table 1 below.

In addition, when the sulfonic acid group content of the obtained immobilized sulfonic acid group-containing activated carbon was measured by elemental analysis of sulfur,
It was 2.5 x 10-' mol/g. The reason for such a small content of sulfonic acid groups is thought to be that the sulfonation was performed in the absence of acetic anhydride, resulting in a very poor reaction efficiency.

The procedure described in Example 1 above was also repeated. However, in this example, for comparison, the treatment temperature was changed to 35 to 45°C. The results obtained are shown in Table 1 below and the attached Figure 3. In this example as well, only a small sulfonic acid group content was obtained, but this cannot be increased even by extending the treatment time because the activation energy for the reaction to proceed cannot be exceeded due to the low temperature. It is.

The procedure described in Example 1 above was repeated. However, in this example, the treatment temperature was changed to 100 to 110°C for comparison. The results obtained are shown in Table 1 below and the attached Figure 3. In this example as well, only a small content of sulfonic acid groups was obtained, but this is thought to be because the surface of the activated carbon was attacked by sulfuric acid due to the high treatment temperature. That is, it is thought that the carbon constituting the activated carbon reacted with sulfuric acid, causing carbon to be missing from the activated carbon and the activated carbon to be eroded. It is believed that because sulfuric acid was used in the above reaction rather than in sulfonation, the amount of sulfonic acid groups was reduced as a result.

The procedure described in Example 1 above was repeated. However, in this example, for comparison, the amount of concentrated sulfuric acid added to 200 g of activated carbon fiber was changed to 60 d. The results obtained are shown in Table 1 below and the attached Figure 3.

In this example as well, only a small content of sulfonic acid groups was obtained, but this is thought to be due to a decrease in the efficiency of sulfonation due to the small amount of concentrated sulfuric acid added.

The procedure described in Example 1 above was repeated. However, in this example, for comparison, 400ad of acetic anhydride and 90j of concentrated sulfuric acid!
l! Add 200g of activated carbon to the mixed solution and set the treatment temperature to 60~
The reaction treatment was carried out at 70°C for 3 hours.

The results obtained are shown in Table 1 below and in the accompanying Figure 3.The procedure described in Example 1 above was repeated. However, in this example, for comparison, the treatment temperature was changed to 50 to 60°C.

The results obtained are shown in Table 1 below and the attached Figure 3.

Comparison ±1 The procedure described in Example 1 above was repeated. However, in this example, for comparison, the treatment temperature was changed to 80 to 90°C. The results obtained are shown in the following Table 1 and the attached Figure 3.

11 From the results shown in Table 1, the activated carbon for deodorization according to the present invention has a higher content of sulfonic acid groups than the conventional activated carbon for deodorization, and due to this, its ammonia adsorption properties are also significantly superior. That is understood.

Furthermore, from the attached Figure 3, the treatment temperature greatly affects the ammonia removal rate, and in the case of the deodorizing activated carbon of the present invention, if an ammonia removal rate of 90% or more is desired, the treatment temperature is preferably 50% to 50%. 90°C1 more preferably 60
It is understood that ~70°C.

Implementation (2) Main The procedure described in Example 1 above was repeated. However, in this example, in order to investigate the effect of the amount of concentrated sulfuric acid added on the ammonia removal rate, the amount of concentrated sulfuric acid added was varied. The attached FIG. 4 is a plot of the obtained results. From the graph in FIG. 4, it is understood that in order to achieve an ammonia removal rate of 90% or more, the amount of concentrated sulfuric acid added (based on 100% activated carbon) must be at least 60% by weight.

〔Effect of the invention〕

The deodorizing activated carbon according to the present invention has sulfonic acid groups fixed to the activated carbon through chemical bonds, whereas the performance of general sulfuric acid-impregnated activated carbon for basic odors is degraded by desorption of sulfuric acid when washed with water or left at high temperatures. Because of this, no deterioration in adsorption performance is observed at all. In addition, in the case of activated carbon impregnated with sulfuric acid, the sulfuric acid aggregates and does not work effectively, whereas in the activated carbon of the present invention,
Since the sulfonic acid groups are uniformly immobilized on the surface of activated carbon, the basic gas removal performance is extremely excellent.

Since the activated carbon for deodorization of the present invention has particularly excellent adsorption properties for basic gases, it can be widely and advantageously used for deodorization.

[Brief explanation of the drawing]

Figure 1 is a graph plotting the ammonia adsorption characteristics of various activated carbons, Figure 2 is a graph plotting the ammonia adsorption characteristics (repetitive tests) of various activated carbons, and Figure 3 is a graph plotting the ammonia adsorption characteristics of various activated carbons. FIG. 4 is a graph plotting the effect of treatment temperature on the ammonia removal rate, and FIG. 4 is a graph plotting the effect of the amount of concentrated sulfuric acid added on the ammonia removal rate. Adsorption time (minutes) Ammonia adsorption characteristics of various activated carbons No. 11 Curve 1...Curve 2 of activated carbon containing immobilized sulfonic acid groups...
・Sulfuric acid impregnated activated carbon curve 3...Non-impregnated activated carbon adsorption time (minutes) 2nd 1111 Non-impregnated activated carbon Effect of treatment temperature on ammonia removal rate Figure 3a Amount of sulfuric acid added (wt%) Ammonia removal rate Figure 4 Effect of added amount of concentrated sulfuric acid on

Claims (1)

[Claims] 1. A deodorizing product obtained by reacting raw material activated carbon and sulfuric acid in the presence of acetic anhydride, and having a sulfonic acid group fixedly chemically bonded to its surface site. activated carbon for use.