JP2008178788A - Adsorbent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adsorbent which is capable of effectively adsorbing and removing lower aliphatic aldehyde without re-scattering even under low-humidity environment with 5g/m<SP>3</SP>or low of absolute humidity. <P>SOLUTION: The adsorbent for low-humidity environment aldehyde is characterized by having a water-soluble hydrazide carried by a porous material of which the amount of equilibrium adsorption at 40% of the relative humidity is 0.1 mL/g or more and of which the amount of equilibrium adsorption at 95% of the relative humidity is 20% or more in the steam adsorption isotherm of 30°C. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an adsorbent excellent in adsorbing and removing aldehydes, particularly lower aliphatic aldehydes typified by acetaldehyde, and more particularly to an adsorbent suitably used for an air filter.

  There are various types of pollutants in the air, but among these, lower aliphatic aldehydes are a major problem. For example, acetaldehyde contained in tobacco smoke, building materials, and exhaust gas from industrial machinery has a very low concentration of 1.5 μg / L as a threshold, that is, a limit point where it is perceived as odor, and even a small amount causes bad odor. Aldehydes are also regarded as a major cause of sick house syndrome and chemical hypersensitivity, and the Ministry of Health, Labor and Welfare has urged regulations by setting indoor concentration guideline values.

  In order to remove malodorous components in the air, activated carbon is generally used. However, the equilibrium adsorption amount of the lower aliphatic aldehyde on the activated carbon is significantly smaller than other malodorous components. Activated carbon once holds malodorous components in its pores, but is physically adsorbed on the surface, so when it reaches adsorption equilibrium, it re-releases malodorous due to environmental changes such as temperature and humidity. There is.

  Therefore, Patent Document 1 and Patent Document 2 disclose activated carbon impregnated with aniline that chemically reacts with aldehyde. However, since aniline is toxic and causes toxic symptoms in the human body by contact or inhalation, it is not suitable for use in situations where it touches human hands.

  In addition, Patent Document 3 improves the removal performance of lower aliphatic aldehydes by mixing a porous material in which phosphoric acid is added to an adsorbent obtained by attaching an amine-organic acid salt to a porous material such as activated carbon. Is disclosed. Patent Document 4 discloses a method of adding an amine to at least one of an inorganic adsorbent and activated carbon. However, in the methods specifically described in these documents, it is difficult for the drug and the aldehyde to react in an environment in which water as a reaction field is unlikely to exist, that is, in a low humidity environment. In other words, there are many known techniques for chemically adsorbing aldehydes by attaching a general amine-based chemical to a porous material, but a practical effect is shown even in a low humidity environment that is disadvantageous for chemical reaction. Adsorbent is not obtained.

In Patent Document 5, for the purpose of improving the adsorption performance of aldehyde, a method in which hygroscopic ethylene urea and aniline or transition metal nitrates, chlorides, acetates, and phosphates are compositely attached to a porous material. Disclosure. However, in this method, when used in a low humidity environment with an absolute humidity of 5 g / m ³ or less, not only the hygroscopicity of ethylene urea is not fully exhibited, but also the reactivity between urea compounds and aldehydes is not fast so Sufficient adsorption performance cannot be obtained under typical conditions.

  Patent Document 6 discloses a deodorant adhesive in which a water-soluble polyamine is supported on silicon dioxide having a specific pore size and water content. However, since polyamine is a compound having physiological activity, its influence on the human body is questioned. This deodorant adhesive is designed to be used for building materials under static conditions. For example, when used in dynamic applications where high-temperature air is vented, such as air filters for OA equipment, There is a problem that it itself emits an odor.

Thus, there has been a demand for an adsorbent that exhibits high adsorption performance for lower aliphatic aldehydes in a low humidity environment and a dynamic environment, and that does not re-release and does not generate odors.
Japanese Patent Publication No. 60-54095 Japanese Patent Laid-Open No. 3-98642 JP-A-6-7418 JP-A-8-191879 JP-A-11-285619 JP 2000-281998 A

  An object of the present invention is to provide a practical adsorbent that is excellent in removal performance of lower aliphatic aldehydes even in a low humidity environment and that has high removal efficiency even under dynamic conditions where air is circulated. And

  That is, according to the present invention, in a water vapor adsorption isotherm at 30 ° C., the equilibrium adsorption amount at a relative humidity of 40% RH is 0.1 mL / g or more, and the equilibrium adsorption amount at a relative humidity of 40% RH is 95% relative humidity. It is an adsorbent obtained by supporting a water-soluble hydrazide on a porous body that is 20% or more of the equilibrium adsorption amount in RH.

  According to the present invention, it is possible to provide an adsorbent that adsorbs aliphatic aldehydes with high efficiency and a large adsorption capacity even in a low humidity environment and a dynamic environment.

  The adsorbent of the present invention is formed by supporting a water-soluble hydrazide on a porous body. The porous body can obtain a surface area that can be contacted with the processing air and can hold a sufficient amount of water-soluble hydrazide.

  The adsorbent of the present invention has an equilibrium adsorption amount of 0.1 mL / g or more at a relative humidity of 40% RH and an equilibrium at a relative humidity of 40% RH in a water vapor adsorption isotherm at 30 ° C. It is important that the adsorption amount is 20% or more of the equilibrium adsorption amount at a relative humidity of 95% RH. By adopting such a porous body, a sufficient amount of water can be maintained even in a low humidity environment, and adsorption by a chemical reaction between aldehyde and hydrazide can be advanced. The water vapor adsorption isotherm can be measured using an apparatus defined in JIS K 1474: 1991 5.1.2.

  Activated carbon, activated alumina, silica gel, zeolite, etc. can be used as the porous material, but the aldehyde adsorption site is secured even after the water-soluble hydrazide is adhered, and it is constant even in a low humidity environment due to capillary condensation. The porous body whose average pore diameter is 1 nm-10 nm is preferable at the point which can hold | maintain this water | moisture content. Among the porous materials, silica gel having a hydrophilic surface is preferable, and among these silica gels, silica gel having an average pore diameter of 3 nm to 6 nm is preferable because it can retain more water.

  When the average pore diameter of the porous body is too large, the capillary condensation action is reduced, and the water retention ability in a low humidity environment is reduced. In addition, if the average pore diameter is large, the specific surface area becomes small, and it is impossible to secure a hydrazide attachment area that can come into contact with the processing air. If the specific surface area is made sufficiently large, the porosity in the porous body becomes too large, the mechanical strength is lowered, and the porous body is destroyed in the process of attaching hydrazide.

  On the other hand, if the average pore diameter is too small, the specific surface area of the porous body increases, but hydrazide is easily clogged in the pores, resulting in a decrease in aldehyde adsorption sites.

  The pore diameter of the porous body is preferably as small as possible, and silica gel having a sharp pore diameter distribution can be used effectively. The pore size distribution of the porous material is obtained by analyzing the adsorption isotherm data obtained by the gas adsorption method by the BJH (Brrett. Joyner. Halenda) method or the HK (Horbath-Kawazoe) method. be able to.

The specific surface area of the porous body is preferably 50m ² / g~600m ² / g. If it is 50 m ² / g or less, the contact efficiency with the aldehyde gas is lowered, and sufficient adsorption performance cannot be obtained. If it is 600 m ² / g or more, the porosity of the porous body becomes too large, the mechanical strength is lowered, and it becomes easy to break in the process of attaching the water-soluble hydrazide.

    When the porous material is a particulate material, the average particle size is preferably 1 to 5000 μm. More preferably, it is 75-4000 micrometers. If the average particle size is less than 1 μm, handling is difficult and reaggregation tends to occur. On the other hand, if it is larger than 5000 μm, it is bulky when used in a limited volume as a filter adsorbent, and the surface area required for gas adsorption cannot be secured. The average particle size is calculated from the particle size of the porous body. The particle size is measured according to the method described in JIS K 0069: 1992 6.2.5 and using a standard sieve defined in JIS Z 8801-1: 2006, and the ratio of passing through the mesh is measured. Expressed as an integrated weight percentage. The particle size having an integrated value of 50% is defined as “average particle size”. However, if it becomes a fine powder of about several μm, the sieve becomes clogged, so it is dispersed in a liquid and the particle size is measured using diffracted light or scattered light.

  The surface of the porous body may be subjected to any post-treatment such as a treatment for increasing water resistance strength or a treatment for changing pH.

On the other hand, the water-soluble hydrazide used in the present invention is a compound in which a hydroxyl group of an acid is substituted with a hydrazino group (NH ₂ —NH—) and is soluble in water. Here, “water-soluble” means that 1% by mass or more (10 g / L) dissolves in neutral water at room temperature.

  Representative compound groups include monohydrazide, dihydrazide, hydrazide imide, hydrazidine, semicarbazide and the like.

The monohydrazide is represented by the general formula R ₁ —CO—NHNH ₂ (wherein R ₁ represents a hydrogen atom, an alkyl group or an aryl group which may have a substituent), and includes form hydrazide, acetohydrazide, 1, Examples include 5-diphenylcarbonohydrazide, benzohydrazide, pentanohydrazide, cyclohexanecarbohydrazide, benzenesulfonohydrazide, thiobenzohydrazide and the like.

Dihydrazide has the general formula H ₂ NHN—R ₂ —NHNH ₂ [wherein R ₂ represents a group —CO— or a group —CO—A—CO—. A represents an alkylene group or an arylene group], and examples thereof include adipic acid dihydrazide, sebacic acid hydrazide, terephthalic acid dihydrazide, and dodecanedioic acid dihydrazide.

The hydrazide imide is represented by the general formula R ₁ C (═NH) NHNH ₂ [wherein R ₁ represents a hydrogen atom, an alkyl group or an aryl group that may have a substituent], and examples thereof include pentaneimide hydrazide. .

Hydrazine is also called hydrazide hydrazone, and is represented by the general formula R ₁ C (= NNH ₂ ) NHNH ₂ [wherein R ₁ represents a hydrogen atom, an alkyl group or an aryl group which may have a substituent]. And benzohydrazonohydrazide.

Semicarbazide is a hydrazide of carbamic acid, and is represented by the general formula NH ₂ —CO—NHNH ₂ (wherein the nitrogen atom and the carbon atom may be substituted with an alkyl group or an aryl group aryl group), An example is 4,4-dimethyl-1-phenyl semicarbazide.

  Of these, dihydrazide compounds are preferred, carboxylic acid dihydrazides are particularly preferred, and adipic acid dihydrazide is even more preferred in consideration of water solubility, reactivity with lower aliphatic aldehydes, safety, productivity, low odor and the like. preferable.

  Such water-soluble hydrazides may be contained alone or in combination of two or more. The amount of water-soluble hydrazide supported is 0.02 to 1.00 mmol per 1 g of the porous body. If the supported amount is too small, the aldehyde gas adsorption ability cannot be obtained. If the loading is too large, hydrazide will clog the pores and not only provide an effective adsorption site, but also cannot retain moisture by capillary condensation, so the chemisorption capacity in a low humidity environment is extremely low. Become.

  Moreover, it is also preferable to carry | support an acid catalyst in the adsorbent of this invention. By sharing an electron of the carbonyl carbon of the aldehyde with the acid catalyst, the electrophilicity of the carbonyl carbon of the aldehyde can be increased, and the chemical adsorption ability for the aldehyde can be improved.

  Examples of the acid of the acid catalyst include Bronsted acid which is a proton donor and Lewis acid which is an electron pair acceptor. Examples of Lewis acids include hydroxides or oxides such as silicon, aluminum, titanium, zirconium, tungsten, molybdenum, tin, and iron, graphite, ion exchange resins, and the like, sulfate groups, antimony pentafluoride, five Examples include those in which tantalum fluoride, boron trifluoride or the like is attached or supported.

  In addition, various additives such as pH adjusters, preservatives, antibacterial agents, and discoloration inhibitors can be supported on the porous body depending on the intended use. For example, adipic acid hydrazide may decompose and discolor due to repeated light irradiation and contact with oxygen in the air over time. This discoloration can be prevented by adding water-soluble hydrazide and equimolar polyethylene glycol to the porous body. Polyethylene glycol acts as a discoloration inhibitor without interfering with the reactivity of aldehyde and hydrazide. The mechanism of discoloration and its suppression is not clearly understood, but it is presumed that polyethylene glycol present in an associated state with hydrazide may moderate the energy absorption of α-carbonyl of acid hydrazide by light irradiation. .

  The adsorbent of the present invention as described above can be easily obtained by mixing a porous body and an aqueous solution in which water-soluble hydrazide is dissolved. In order to uniformly deposit hydrazide in the pores, it is necessary to prepare an amount of an aqueous hydrazide solution that can sufficiently immerse the porous body, and to impregnate and adhere the porous body in the pore for 1 hour or more. The porous body may be dried or pre-hydrated as a pretreatment for impregnating the aqueous solution.

  The amount of hydrazide supported can be adjusted by changing the concentration of the aqueous hydrazide solution. Moreover, you may stir slowly during impregnation. The complex after the hydrazide is deposited is filtered off by an arbitrary method and dried at a temperature lower than the decomposition temperature of the water-soluble hydrazide used. The obtained composite can be thermally dried at, for example, 50 ° C. to 120 ° C. to obtain the aldehyde gas adsorbent in the present invention.

  When normally transparent silica gel is used as the porous body and amines that are hardly soluble in water, for example, are supported on the silica gel, the amine component of the adsorbent is deposited and becomes white. However, the adsorbent of the present invention is characterized by having a transparent appearance. This is presumed that the water-soluble hydrazide is dissolved in the water slightly contained in the porous body, so that the hydrazide molecules are present in a disordered arrangement, and the irregular reflection of light does not occur.

  The adsorbent of the present invention can be used in various fields that require adsorption of aldehyde gas. In particular, even in a low humidity dynamic environment, the sorbent can be selectively used without being inhibited by other VOC gases. It can be removed with high efficiency. This is achieved by supporting a water-soluble hydrazide having high reactivity with aldehydes on a porous body capable of holding sufficient moisture even under low humidity. That is, it is considered that the moisture contained in the porous body works effectively as a reaction field and promotes the reactivity of hydrazide.

  In particular, since the equipment itself is exposed to a high temperature in the exhaust part of the electrophotographic apparatus, air is supplied and air having a low absolute humidity is supplied. The present invention has a need for an aldehyde adsorbent used for a filter installed in such a low humidity environment.

  Examples of aldehydes to be adsorbed include aliphatic aldehydes such as formaldehyde, acetaldehyde, and propionaldehyde, and aromatic aldehydes such as benzaldehyde and paramethylbenzaldehyde. And this invention expresses favorable chemical adsorption performance with respect to acetaldehyde which was difficult to remove under dynamic conditions because of low reactivity, regardless of the humidity environment.

  Hereinafter, although an example shows the operation effect of the present invention more concretely, the adsorbent of the present invention is not limited only to the following example.

[Measuring method]
(1) Method for measuring water vapor adsorption isotherm About 100 mg of a porous material was sampled and heated and evacuated at 180 ° C. for 2 hours. Next, it was left overnight in a vacuum line under saturated water vapor pressure. Then, vacuum evacuation was performed at room temperature of 30 ° C., and the amount of adsorbed water was gradually increased in a range of relative pressure of water vapor of 0.00 to 1.00 by a constant volume method using a device name BELSORP 18 PLOST-T manufactured by Japan BEL. The sample was measured at 30 points while raising the water vapor adsorption isotherm of the sample.

In addition, the 30 degreeC water vapor | steam equilibrium adsorption amount characteristic of the porous body shown in Table 2 mentioned later is shown by following Formula.
A: Water vapor equilibrium adsorption amount (mL / g) at 30 ° C. and relative humidity 40% RH
B: [(A) / (water vapor equilibrium adsorption amount at 30 ° C., relative humidity 95RH%) × 100] (%)
(2) Measuring method of average pore diameter and BET specific surface area About 100 mg of a porous material was sampled and weighed after vacuum drying at 180 ° C. for 2 hours. Using an automatic specific surface area device manufactured by Micromeritics, the device name Gemini 2375, the adsorption amount of nitrogen gas at the boiling point of liquid nitrogen (-195.8 ° C.) is gradually increased in the range of relative pressure of 0.02 to 1.00. The sample was measured at 40 points while increasing the temperature to obtain a nitrogen adsorption isotherm of the sample. The results at a relative pressure of 0.02 to 1.00 were BET-plotted to determine the BET specific surface area (m ² / g) per weight. Moreover, the pore volume (mL / g) of the porous body was obtained by the BET method of hot springs such as nitrogen adsorption, and the average pore diameter (D) of the porous body was calculated from the following formula.
D = 4 × V / S × 10 ⁴
[V: pore volume (mL / g), S: specific surface area (m ² / g)]
(3) Evaluation of acetaldehyde adsorption capacity (one-pass removal efficiency) A cylindrical sample holder having a diameter of 45 mm was filled with an adsorbent to a height of 10 mm, and the temperature was 23 ° C. and the absolute humidity was 2 g / m ³ (relative humidity). 10% RH) air was blown at a speed of 0.16 m / sec for 30 minutes to sufficiently dry the test system. Further, the dry air was ventilated from the upstream side while supplying acetaldehyde at an upstream concentration of 20 volppm by a standard gas cylinder. Air is sampled on the upstream and downstream sides of the sample holder, and each acetaldehyde concentration is measured over time using an infrared absorption type continuous monitor. From the following formula, aeration starts 5 minutes, 10 minutes, 15 minutes The one-pass removal efficiency after 20 minutes was calculated.
One-pass removal efficiency (%) = (1− (downstream concentration / upstream concentration)) × 100
(4) Evaluation of acetaldehyde re-release property A cylindrical sample holder with a diameter of 45 mm is filled with an adsorbent at a height of 10 mm, and this is dry air at a temperature of 23 ° C. and an absolute humidity of 2 g / m ³ (relative humidity of 10% RH). Was blown at a speed of 0.16 m / sec for 30 minutes to sufficiently dry the test system. Further, acetaldehyde was supplied from the upstream side with a standard gas cylinder so as to have an upstream concentration of 33 vol ppm, and when aerated for 25 minutes, the supply of acetaldehyde was stopped. The sample was sealed and once removed from the test system, and the above dry air was allowed to flow for 5 minutes, and the acetaldehyde adhering to the test system (upstream and downstream of the sample) was cleaned with an air blow. The sample was set again and the dry air was vented for 15 minutes. The downstream acetaldehyde concentration at 5 minutes, 10 minutes and 15 minutes after the start of aeration was measured with an infrared absorption type continuous monitor.

(5) Odor sensory evaluation method after loading with aldehyde gas Remove the sample after completion of the acetaldehyde adsorption capacity evaluation from the test system and remove the odor generated from the sample according to the 6-step odor sensory evaluation criteria (Table 1). A to D).

[Example 1]
The adsorbent of the present invention was obtained using the following.

  As a water-soluble hydrazide, 12 g of adipic acid dihydrazide (manufactured by Nippon Kasei Co., Ltd.) was weighed and dissolved in 200 mL of distilled water at room temperature. The obtained aqueous solution of adipic acid dihydrazide was impregnated with 100 g of the following porous material, and stirred slowly for 1 hour. Next, this porous body was separated by natural filtration and dried at a drying temperature of 100 ° C. for 1 hour to obtain an adsorbent. Table 2 summarizes the conditions for preparing the adsorbent.

  The obtained adsorbent was evaluated for acetaldehyde adsorption capacity, re-release property, and odor after loading. The results are shown in Tables 3-5.

(Porous body)
As a porous body, “CariACT Q-3” manufactured by Fuji Silysia Chemical Ltd. having a pore volume of 0.3 mL / g, a specific surface area of 550 m ² / g, an average pore diameter of 3 nm, and a particle diameter of 0.85 to 1.70 mm is used. It was.

[Example 2]
An adsorbent was obtained in the same manner as in Example 1 except that the porous body was changed to the following and the amount of water-soluble hydrazide supported was changed. The conditions are summarized in Table 2.

  The obtained adsorbent was evaluated for acetaldehyde adsorption capacity, re-release property, and odor after loading. The results are shown in Tables 3-5.

(Porous body)
As a porous body, “CariACT Q-6” manufactured by Fuji Silysia Chemical Ltd. having a pore volume of 0.6 mL / g, a specific surface area of 450 m ² / g, an average pore diameter of 6 nm, and a particle diameter of 1.70 to 4.00 mm is used. It was.

[Example 3]
An adsorbent was obtained in the same manner as in Example 1 except that the porous body was changed to the following and the amount of water-soluble hydrazide supported was changed. The conditions are summarized in Table 2.
The obtained adsorbent was evaluated for acetaldehyde adsorption capacity, re-release property, and odor after loading. The results are shown in Tables 3-5.

(Porous body)
As a porous body, “CariACT Q-10” manufactured by Fuji Silysia Chemical Ltd. having a pore volume of 1.0 mL / g, a specific surface area of 300 m ² / g, an average pore diameter of 10 nm, and a particle diameter of 1.70 to 4.00 mm is used. It was.

[Comparative Example 1]
An adsorbent was obtained in the same manner as in Example 1 except that the porous body was changed to the following and the amount of water-soluble hydrazide supported was changed. The conditions are summarized in Table 2.

  The obtained adsorbent was evaluated for acetaldehyde adsorption capacity, re-release property, and odor after loading. The results are shown in Tables 3-5.

(Porous body)
As the porous body, activated carbon “Kuraray Coal GG10 / 20” manufactured by Kuraray Chemical Co., Ltd. having an average pore diameter of 1.1 nm, a specific surface area of 1450 m ² / g, and a particle diameter of 0.85 to 1.70 mm was used.

[Comparative Example 2]
An adsorbent was obtained in the same manner as in Example 1 except that the porous body was changed to the following and the amount of water-soluble hydrazide supported was changed. The conditions are summarized in Table 2.

  The obtained adsorbent was evaluated for acetaldehyde adsorption capacity, re-release property, and odor after loading. The results are shown in Tables 3-5.

(Porous body)
As a porous body, “CariACT Q-15” manufactured by Fuji Silysia Chemical Ltd. having a pore volume of 1.0 ml / g, a specific surface area of 200 m ² / g, an average pore diameter of 15 nm, and a particle diameter of 1.70 to 4.00 mm is used. It was.

[Comparative Example 3]
Without using water-soluble hydrazide, the following porous material was used as an adsorbent. With respect to this adsorbent, the acetaldehyde adsorption capacity, re-release property, and odor after loading were evaluated. The results are shown in Tables 3-5.

(Porous body)
As a porous body, “CariACT Q-3” manufactured by Fuji Silysia Chemical Ltd. having a pore volume of 0.3 mL / g, a specific surface area of 550 m ² / g, an average pore diameter of 3 nm, and a particle diameter of 0.85 to 1.70 mm is used. It was.

[Comparative Example 4]
Without using water-soluble hydrazide, the following porous material was used as an adsorbent. With respect to this adsorbent, the acetaldehyde adsorption capacity, re-release property, and odor after loading were evaluated. The results are shown in Tables 3-5.

(Porous body)
As a porous body, “CariACT Q-6” manufactured by Fuji Silysia Chemical Ltd. having a pore volume of 0.6 mL / g, a specific surface area of 450 m ² / g, an average pore diameter of 6 nm, and a particle diameter of 1.70 to 4.00 mm is used. It was.

[Comparative Example 5]
An adsorbent was obtained in the same manner as in Example 1 except that tetraethylenepentamine (manufactured by Tosoh Corporation) was used instead of adipic acid dihydrazide and the amount of water-soluble hydrazide supported was changed. The conditions are summarized in Table 2.

  The obtained adsorbent was evaluated for acetaldehyde adsorption capacity, re-release property, and odor after loading. The results are shown in Tables 3-5.

  In Examples 1 and 2, the removal efficiency 5 minutes after the start of measurement is 95% or more, and the initial removal efficiency is high. Since the removal efficiency of 90% or more is maintained even after 20 minutes, it can be seen that the decrease in adsorption performance is gradual and the life is long.

  In Example 3, compared with Examples 1 and 2, the porous body used for the carrier had a low water vapor equilibrium adsorption characteristic, and although the aldehyde removal efficiency was slightly inferior, adsorption performance, re-release property, and sensory evaluation were sufficient. The level.

  In Comparative Example 1, the equilibrium adsorption amount (mL / g) at a relative humidity of 40% RH is 0.029, and the equilibrium adsorption amount at a relative humidity of 40% RH is the equilibrium adsorption amount at a relative humidity of 95% RH. Adipic acid hydrazide is impregnated with 2.5% activated carbon as a carrier. The activated carbon has most pore diameters distributed in the micropore region and exhibits high acetaldehyde removal efficiency, but has the disadvantage of high re-release properties. It is clear from the odor evaluation after loading. This is presumed that, in a low-humidity environment, the water content of the activated carbon is too small, so that only physical adsorption contributes and the chemical adsorption function of the adsorbing drug is not exhibited.

  In Comparative Example 2, silica gel having an average pore diameter of 15 nm was used as a porous material and adipic acid dihydrazide was impregnated, and the adsorption performance was extremely low. This is presumably because the moisture retention due to capillary condensation is insufficient due to the large average pore diameter of silica gel, and the chemisorption characteristics are not exhibited in a low humidity environment.

  In Comparative Examples 3 and 4, the same porous body as in Examples 1 and 2 was a porous body, and water-soluble hydrazide was not added. These have high removal efficiency, but have high re-releasing properties because aldehyde is adsorbed only by the physical adsorption characteristics of the porous material. Actually, the odor level after loading was also high.

  In Comparative Example 5, tetraethylenepentamine, which is a water-soluble polyamine, was supported instead of the water-soluble hydrazide. Due to the low chemical reactivity of polyamine compounds to aldehydes relative to hydrazide, the removal efficiency is lower than that of the adsorbent of the present invention. Moreover, although the re-release concentration of acetaldehyde was low, the result of the high odor level after loading was due to odor due to volatilization of the supported polyamine itself.

  From the above results, it can be seen that the adsorbent of the present invention exhibits excellent aldehyde adsorption performance under dynamic conditions in a low-humidity environment, and further has a feature that the aldehyde once adsorbed is not re-released.

  The adsorbent of the present invention is an adsorbent for adsorbing aldehyde gas in the passenger compartment of automobiles, railway vehicles, etc., for air cleaners used in healthy houses, pet-friendly condominiums, elderly entrance facilities, hospitals, offices, etc. It can be used as an adsorbent for air filters such as filters, air conditioner filters, building air conditioner filters, and industrial clean room filters. In particular, an exhaust filter installed in an electrophotographic apparatus is ventilated with air having a low absolute humidity because the operating temperature of the apparatus is high. The aldehyde adsorbent of the present invention can be preferably used as an adsorbent for a filter assumed to be used in such a low humidity environment.

Claims (2)

In the water vapor adsorption isotherm at 30 ° C., the equilibrium adsorption amount at a relative humidity of 40% RH is 0.1 mL / g or more, and the equilibrium adsorption amount at a relative humidity of 40% RH is an equilibrium adsorption at a relative humidity of 95% RH. An adsorbent obtained by supporting a water-soluble hydrazide on a porous body of 20% or more of the amount. The adsorbent according to claim 1, wherein the porous body is silica gel having an average pore diameter of 1 to 10 nm.