JP2005224703A - Auto-regenerating filter for removing harmful gas, its manufacturing method, air purifier and air conditioning system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an auto-regenerating filter for removing harmful gas, by which harmful gas in the indoor air, particularly, harmful gas such as formaldehyde and acetaldehyde being main causative agents of a sick house syndrome can be removed efficiently, which exerts a very rapid action on harmful gas when air is purified and whose function of removing harmful gas can be regenerated automatically without necessitating a special regenerating means. <P>SOLUTION: This filter for removing harmful gas has such a structure that the main body portion 11 of this filter or the surface layer portion of an air passage is composed of a material obtained by combining a moisture absorbing material 12 and a normal temperature-active catalyst 13, and a condensed water curtain 14 for dissolving water-soluble harmful gas contained in the air is formed on the surface of the moisture absorbing material 12. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a self-regenerative harmful gas removal filter that removes pollutants contained in the air, particularly VOC gas considered to be the cause of so-called sick house syndrome, and purifies contaminated air, and a method for producing the same. . The present invention also relates to an air purifier or an air conditioning system that removes and purifies water-soluble VOC gas, formaldehyde or acetaldehyde.
Here, VOC is an abbreviation for volatile organic compounds, and is a volatile organic compound that easily volatilizes at room temperature. There are various materials such as formaldehyde, acetaldehyde, toluene, xylene, ethylbenzene, and styrene.

  In recent years, contamination of indoor air has become a problem as heat insulation and airtightness of living spaces progress in order to enhance the cooling and heating effect. Gaseous pollutants include odorous gases and harmful gases. The former is uncomfortable, but the latter causes so-called sick house syndrome, which is a big social problem. A volatile organic compound (VOC) is mentioned as a causative substance of sick house syndrome. Examples of the VOC gas include formaldehyde, acetaldehyde, toluene, xylene, ethylbenzene, styrene, and the like. The main causative substance of sick house syndrome is said to be formaldehyde. In addition, examples of the generation source of such harmful gases include interior building materials such as flooring, walls, and ceilings, and furniture. As a means of removing harmful gas, it is common to purify the indoor polluted air using an air purifier, and the activated air purification method, catalyst method, photocatalyst method are used as air purification methods in practical use. Etc.

  For example, since a harmful gas removal filter made of activated carbon is installed in an air passage, it can quickly adsorb harmful gases in the air stream and has a high air purification effect. However, the adsorption performance of formaldehyde and acetaldehyde is basically low. When the harmful gas molecules are adsorbed on the pore surface of the activated carbon and the entire pore surface is covered with these molecules, the purification effect is lost and the life is extended. The activated carbon method is excellent in air purification performance, but it is not preferable from the standpoint of economic efficiency and global environmental conservation because it is disposable.

  Catalytic system that purifies by oxidative decomposition of harmful gases in the airflow with a catalyst installed in the air passage, and generates active molecules by irradiating fine particles of titanium oxide with ultraviolet rays, causing chemical reaction with harmful gases in the airflow In the photocatalyst method that purifies by generating water, the chemical reaction rate is slower than the adsorption rate of the activated carbon method, so the immediate effect of the purification effect is low.

  There are no conventional examples regarding regeneration of harmful gas removal filters, but there are various conventional examples regarding regeneration of odor gas removal filters. For example, Patent Documents 1 to 4 show means for desorbing and regenerating odor molecules adsorbed for using the odor gas removal filter for a long period of time with an electric heater. Further, for example, Patent Document 5 discloses a means for regenerating the adsorbed odor molecule by photolysis with a photocatalyst.

JP 63-127759 A (Claim 1, FIG. 1) Japanese Patent Laid-Open No. 2-78418 (Claim 1, FIG. 1) JP-A-3-233237 (Claim 1, FIG. 1) JP-A-9-187624 (Claim 1, FIG. 1) Japanese Patent Laid-Open No. 10-227469 (Claim 1, FIG. 1, FIG. 2)

However, the methods of regenerating the deodorizing function of the filter using an electric heater as disclosed in Patent Documents 1 to 4 require a special regenerating means called an electric heater to be assembled to the filter. In addition, since the deodorizing function is interrupted during the regeneration period, there is a problem in that no harmful gas removal and air purification are performed during that time.
Further, even in a method for regenerating the deodorizing function of the photocatalyst by introducing light from the outside as disclosed in Patent Document 5, a special regenerating means called light from the outside must be provided in the apparatus, There is a problem similar to the regeneration method using an electric heater.

The present invention has been made in view of the above-mentioned problems, and the first problem is to efficiently use harmful gases in room air, particularly harmful gases such as formaldehyde and acetaldehyde, which are the main causative substances of sick house syndrome. The object is to obtain a self-regenerative harmful gas removal filter that can be removed well, has a high air purification effect, and can regenerate the harmful gas removal function without requiring a special regenerating means.
A second problem is to obtain a manufacturing method capable of manufacturing such a self-regenerating harmful gas removal filter at low cost.
A third problem is to provide an air purifier and an air conditioning system that purify indoor air by using such a self-regenerating harmful gas removal filter.

  The self-regenerating harmful gas removal filter according to the present invention comprises a composite of a hygroscopic material and a room temperature active catalyst, and further, condensed water that dissolves water-soluble harmful gas in the air on the surface of the hygroscopic material. It has a film.

  The present invention efficiently removes water-soluble harmful gases by dissolving water-soluble harmful gases such as formaldehyde and acetaldehyde, which are the main causative substances of sick house syndrome, in the water film condensed on the surface of the hygroscopic material. And has a high air purification effect. Moreover, since the room temperature active catalyst combined with the hygroscopic material gradually oxidizes and decomposes the water-soluble harmful gas dissolved in the water film, the harmful gas removing function can be self-regenerated.

Embodiment 1 FIG.
FIG. 1 is a conceptual diagram showing the principle of a self-regenerative harmful gas removal filter according to Embodiment 1 of the present invention, and FIG. 2 is a schematic enlarged cross-sectional view showing a portion A of FIG.
As shown in FIG. 2, the self-regenerative harmful gas removal filter 10 is composed of a composite of a hygroscopic material 12 and a normal temperature active catalyst 13 as shown in FIG. It has the water film 14 formed with the water | moisture content condensed on the surface. That is, if it is a high performance hygroscopic material, the condensed water film 14 exists on the surface of the hygroscopic material 12 even at low humidity at room temperature. In FIG. 1, G indicates a water-soluble harmful gas in the air and shows a state in which it is dissolved in the water film 14.

  It is preferable that the hygroscopic material 12 has a concavo-convex surface so as to dissolve a large amount of water-soluble harmful gas and to increase the surface area. As the hygroscopic material 12, hygroscopic ceramics which is a hygroscopic porous material is used. As the hygroscopic ceramic, a material based on silica gel or zeolite is preferably used.

  As the room temperature active catalyst 13 combined with the hygroscopic material 12, a catalyst in which a noble metal and a metal oxide are combined is used. As the noble metal, gold, platinum, iridium, palladium, rhodium and ruthenium are used. As the metal oxide, tin oxide, manganese oxide, tantalum oxide, zirconium oxide, titanium oxide, cerium oxide, or the like is used.

  A catalyst mainly composed of a metal oxide can also be used as the room temperature active catalyst 13 that is combined with the hygroscopic material 12. As the metal oxide in this case, tin oxide, manganese oxide, tantalum oxide, zirconium oxide, titanium oxide, cerium oxide, or the like is used.

  The self-regenerative harmful gas removal filter 10 is made of, for example, a fine powder of silica gel as the hygroscopic material 12 and a fine particle of manganese oxide, for example, as a room temperature active catalyst 13 and a fine inorganic binder (not shown). It is manufactured by adding to water, forming by adding water, drying and firing. Then, water vapor in the air is adsorbed on the surface of the silica gel, and the condensed water is distributed so as to cover the surface of the pores. As a result, the condensed water film 14 is formed on the surface of the silica gel that is the hygroscopic material 12. The thickness of the water film 14 is 1 μm or less.

  Next, a harmful gas to be removed by the self-regenerating harmful gas removal filter 10, particularly a VOC gas will be described.

  As described above, VOC gas generated from building materials and furniture is considered to be the cause of sick house syndrome. Examples of the VOC gas include formaldehyde, acetaldehyde, toluene, xylene, ethylbenzene, styrene, and the like. The main causative substance of sick house syndrome is said to be formaldehyde.

  Formaldehyde and acetaldehyde, which are the main components of VOC gas, are lower aldehydes and have a property of dissolving in water. The aldehyde is characterized by being a water-soluble harmful gas that dissolves in the presence of moisture.

  According to one theory, formaldehyde in indoor air reacts with oxidizing gases in the air (NOx and oxidants that are air pollutants) to produce formic acid, which is a lower fatty acid. Some say that it is the causative agent. Acetaldehyde also produces acetic acid, which is a lower fatty acid, when chemically reacted with oxidizing gas in the air.

  Formic acid and acetic acid, which are the lower fatty acids, are also water-soluble, and are characterized by being water-soluble gases that dissolve in the presence of moisture.

  Therefore, the action of the self-regenerating harmful gas removal filter 10 on the contaminated indoor air mainly composed of the VOC gas as described above will be described.

  When air containing contaminants such as water-soluble VOC is passed through the filter 10 and the water-soluble harmful gas G in the air contacts the condensed water film 14 covering the surface of the hygroscopic material 12, the water-soluble harmful gas G is dissolved and taken into the water film 14. Since the hygroscopic material 12 is a composite of the normal temperature active catalyst 13, the normal temperature active catalyst 13 gradually oxidizes the water-soluble harmful gas G dissolved in the water film 14, and finally harmless. It oxidizes until it becomes water and carbon dioxide. Carbon dioxide is released into the air. Thus, the filter 10 is self-regenerated by oxidizing and decomposing the water-soluble harmful gas G dissolved in the water film 14 by the room temperature active catalyst 12 in contact with the water film 14.

  According to the present embodiment, polluted air containing water-soluble harmful gas as a main component is passed through the filter 10, and the water-soluble harmful gas is dissolved in the water film 14 condensed on the surface of the hygroscopic material 12. Water-soluble harmful gas can be removed and air can be purified. Accordingly, it is possible to quickly and efficiently remove formaldehyde and acetaldehyde, which are causative substances of sick house syndrome. Furthermore, since these dissolved water-soluble harmful gases are gradually oxidized and decomposed by the room temperature active catalyst 13 combined with the hygroscopic material 12, the self-regeneration of the filter is possible, and the water-soluble harmful gas removal function is achieved. No special reproduction means for reproduction is required. Therefore, since the filter can self-regenerate, the water-soluble harmful gas removing function of the filter is not interrupted during the regeneration period, and can be used for a long period of time without maintenance. Moreover, since it is not disposable, it is economical and advantageous from the standpoint of global environmental conservation.

  Moreover, since the hygroscopic material is a hygroscopic ceramic, it can be easily combined with a room temperature active catalyst, and the life of the filter can be extended.

  Furthermore, since the room temperature active catalyst is a catalyst in which a noble metal and a metal oxide are combined, there is an effect of promoting the oxidative decomposition action of the water-soluble harmful gas.

  In the following, more specific embodiments to which the present invention is applied will be described.

Embodiment 2. FIG.
FIG. 3 is an exploded perspective view of the self-regenerating harmful gas removal filter according to Embodiment 2 of the present invention.
In the present embodiment, as shown in FIG. 3A, the filter main body portion is constituted by a honeycomb structure 16 having a plurality of lattice-like through holes (air passages) 15.

  In other words, silica gel is used as a hygroscopic material, and a rectangular honeycomb structure 16 having a plurality of lattice-like through holes (air passages) 15 is produced through a normal ceramic manufacturing process. Specifically, the raw material is formed into a lattice shape using cordierite (bitumenite) as a binder and fired in a firing furnace. Next, the self-regenerating harmful gas removal filter 10A is obtained by supporting manganese oxide as a metal oxide and platinum as a noble metal on the surface of the honeycomb structure 16 mainly through the through holes 15.

  The self-regenerating harmful gas removal filter 10A can be used in the form (honeycomb structure) as shown in FIG. 3A, but is further made of metal or synthetic resin as shown in FIG. It can reinforce by incorporating in the filter frame 17. As a fixing means for the honeycomb structure 16, general bonding, screwing, or the like is used. Alternatively, the elastic force of the cut and raised pieces (not shown) provided in the filter frame 17 is used, and the cut and raised pieces are engaged with the recesses (not shown) provided on the outer peripheral portion of the honeycomb structure 16. It is good also as a structure to match.

  In the self-regenerating toxic gas removal filter 10A of the present embodiment, the water-soluble state as described in the first embodiment in the process in which contaminated air passes through the plurality of lattice-like through holes 15 of the honeycomb structure 16. It removes and decomposes harmful harmful gases, purifies air, and performs self-regeneration of the filter. Furthermore, since it is formed into a honeycomb shape with a hygroscopic material, it is possible to realize a low pressure loss of the filter, and an immediate effect of removing water-soluble harmful gas is extremely high.

Embodiment 3 FIG.
FIG. 4 is an exploded perspective view of the self-regenerating harmful gas removal filter according to Embodiment 3 of the present invention.
In the present embodiment, as shown in FIG. 4A, the filter main body portion is provided with wave plate portions 18a and flat plate portions 18b alternately up and down (or may be alternately left and right in the vertical direction) to form a plurality of half-moon shaped air. A honeycomb structure 18 having a passage 18c is used.

  Specifically, zeolite is used as the hygroscopic material, and a mixed aqueous solution of zeolite and inorganic fiber pulp is wet-made to make a zeolite-mixed paper. By subjecting this zeolite mixed paper to corrugation processing partially and intermittently, a honeycomb-like structure 18 having corrugated plate portions 18a and flat plate portions 18b alternately above and below is obtained. Next, manganese oxide as a metal oxide and platinum as a noble metal are supported on each surface of the corrugated plate portion 18a and the flat plate portion 18b of the honeycomb structure 18, that is, the surface of each air passage 18c. By incorporating this into a filter frame 19 made of metal or synthetic resin, a self-regenerating harmful gas removal filter 10B reinforced in strength can be obtained.

  In the self-regenerating harmful gas removal filter 10B of the present embodiment, a gap formed by the corrugated plate portion 18a and the flat plate portion 18b of the honeycomb structure 18 becomes a passage through which air passes (air passage 18c). The effect is the same as that of the second embodiment. However, the cost is lower than that of the second embodiment.

  The basic functions and effects of the self-regenerating harmful gas removal filters 10A and 10B produced in the second embodiment and the third embodiment are as described above. Here, in order to compare and evaluate the performance of the filters 10A and 10B, the test results of the pressure loss of the filter and the removal efficiency of the water-soluble harmful gas are shown below.

(1) About the pressure loss of the filter Since the pressure loss of the filter depends on the wind speed, the filter for each of the self-regenerating harmful gas removal filters 10A and 10B at a wind speed of 0.2 to 1.0 m / s which is a general use range. The pressure loss of was measured. The results are shown in Table 1.

  From Table 1, the filter 10A shows a lower pressure loss value than the filter 10B, but any filter 10A, 10B can be used practically and can be used as a water-soluble harmful gas removal filter. It was confirmed that the pressure loss was.

(2) About removal efficiency of water-soluble harmful gas The removal performance of harmful gas is the ratio of removal of harmful gas when air containing harmful gas passes through each filter 10A, 10B once. It shall be expressed as Transient removal efficiency was measured for typical formaldehyde, acetaldehyde, formic acid and acetic acid as water-soluble harmful gases. Since the transient removal efficiency depends on the wind speed, Table 2 shows the measurement results of the transient removal efficiency of the filters 10A and 10B at wind speeds of 0.2 m / s, 0.5 m / s, and 1.0 m / s.

From Table 2, it can be seen that each of the filters 10A and 10B has high transient removal efficiency.
In addition, as a result of using a self-regenerating harmful gas removal filter for formaldehyde and acetaldehyde, which are the main causative substances of sick house syndrome, the above harmful gases can be removed with high efficiency, and the self-regenerating function can be used for a long time without maintenance. It was confirmed.

  In addition, as a result of using a self-regenerative harmful gas removal filter for formic acid and acetic acid produced by chemical reaction of formaldehyde and acetaldehyde with oxidizing gas in the air, the harmful gas is removed with high efficiency, and It was confirmed that the self-regeneration function can be used for a long time without maintenance.

  Further, another self-regenerative harmful gas removal filter in which only the metal oxide mainly composed of manganese oxide is supported on the surface of each air passage of the honeycomb structures 16 and 18 is obtained, and the harmful gas removal performance is obtained. As a result of the evaluation, the performance was lower than in Table 2, but it was confirmed that the transient removal efficiency was 50% or more at a wind speed of 1 m / s, and there was practicality. In this case, there is an advantage that the cost is low because no precious metal is used.

(Other variations)
In Embodiment 1 described above, the filter main body portion is entirely composed of a composite of a hygroscopic material and a room temperature active catalyst. In the second and third embodiments, the filter portion is made of a hygroscopic material. However, since the filter body portion only needs to have some strength such as impact, it is not necessary to manufacture the entire filter body portion from the above-described material. In light of the problem of the present invention, any filter may be used as long as it exhibits the above-described function of removing harmful gases in the portion of the passage of air through the filter. That is, in FIG. 1 described above, the portion indicated by reference numeral 11 can also be regarded as the surface layer portion of the air passage. In this case, only the surface layer portion of the air passage only needs to be composed of a composite material of a hygroscopic material and a room temperature active catalyst. For example, a surface layer portion having characteristics close to that of a porous material can be obtained by applying a composite material on the surface of the air passage using coating, spraying, or the like.

  Note that the outer shape of the filter and the cross-sectional shape of the air passage are not particularly limited. The shape may be any shape such as a circle, a rectangle, an ellipse, or a polygon.

Embodiment 4 FIG.
FIG. 5 is a schematic configuration diagram of an air cleaner according to Embodiment 4 of the present invention.
In the present embodiment, the self-regenerating harmful gas removal filter 10A (or 10B) shown in the second embodiment or the third embodiment is used.
In FIG. 5, a dust removal filter 24, a self-regenerative harmful gas removal filter 10 </ b> A (10 </ b> B), and a blower 25 are installed in the air passage 22 in the casing 21 of the air purifier 20 in order from the air intake 23. The air cleaned from 26 is blown into the room.

  In the air cleaner 20, air containing formaldehyde and acetaldehyde is sucked into the casing 21 from the air intake 23 by the blower 25. The suction air passage 22 is provided with a dust removal filter 24 and a self-regenerating harmful gas removal filter 10A (10B) according to the present invention. Particulate matter contained in room air is first collected by the dust removal filter 24, Formaldehyde and acetaldehyde, which are water-soluble harmful gases, are dissolved and removed by the self-regenerating harmful gas removal filter 10A (10B). The cleaned air is blown out into the room from the air outlet 26. As described above, the indoor air is circulated by the blower 25, thereby purifying the indoor air.

  It was confirmed that formaldehyde and acetaldehyde dissolved and removed in the water film condensed on the surface of the hygroscopic material of the self-regenerative harmful gas removal filter were gradually oxidized and decomposed by the normal temperature active catalyst, and the harmful gas removal filter was self-regenerated. .

  In the case of using an air cleaner provided with a dust removal filter and a self-regenerating harmful gas removal filter as in the present embodiment, particulate matter contained in the indoor air is collected by the dust removal filter, Formaldehyde and acetaldehyde, which are toxic harmful gases, are dissolved and removed by a self-regenerating harmful gas removal filter, and the dissolved harmful gases can be regenerated by gradually oxidizing and decomposing with the above-mentioned normal temperature active catalyst, so maintenance-free and long-term It can be used over a wide range, and is advantageous from the standpoints of economic and global environmental conservation.

Embodiment 5 FIG.
FIG. 6 is a schematic configuration diagram of an air conditioning system according to Embodiment 5 of the present invention.
In the present embodiment, the self-regenerating harmful gas removal filter 10A (or 10B) shown in the second embodiment or the third embodiment is used.
In FIG. 6, the air conditioning system 30 includes an air duct 32 communicating with an air conditioner (not shown) in a casing 31, and the air passage from the air duct 32 and the air passage from the air intake port 33 are blown by the blower 34 in the casing 31. It has come to join. A dust collection filter 35 is installed in the air duct 32, and the self-regenerating harmful gas removal filter 10 </ b> A (10 </ b> B) is installed in the vicinity of the air intake 33.

  In the air conditioning system 30, air containing formaldehyde or acetaldehyde is sucked into the casing 31 from the air intake 33 by the blower 34. Similarly, air-conditioned room air is also sucked into the casing 31 from the air duct 32. The particulate matter contained in the indoor air mainly conditioned by the dust filter 35 provided in the air duct 32 is collected, and formaldehyde and acetaldehyde, which are water-soluble harmful gases, are provided in the air intake 33. It is dissolved and removed by the self-regenerating harmful gas removal filter 10A (10B). The cleaned air is blown out into the room from the air blowing port 36. In this way, the indoor air is circulated by the blower 35, whereby the purification of the indoor air proceeds in parallel with the air conditioning.

  It was confirmed that the water-soluble harmful gas dissolved and removed in the water film condensed on the hygroscopic material surface of the self-regenerative harmful gas removal filter was gradually oxidized and decomposed by the normal temperature active catalyst, and the harmful gas filter was self-regenerated. .

  When an air conditioning system provided with a dust removal filter and a self-regenerating harmful gas removal filter is used as in the present embodiment, particulate matter contained in the indoor air is collected by the dust removal filter and is soluble in water. Hazardous formaldehyde and acetaldehyde are dissolved and removed with a self-regenerative harmful gas removal filter, and the dissolved harmful gas can be regenerated by gradually oxidizing and decomposing with the above-mentioned normal temperature active catalyst. It can be used, and it is advantageous from the standpoints of economic protection and global environmental protection.

It is a conceptual diagram which shows the principle of the self regeneration type | mold harmful gas removal filter in Embodiment 1 of this invention. It is a typical expanded sectional view of the A section of FIG. It is a disassembled perspective view of the self reproduction | regeneration type | mold harmful gas removal filter which shows Embodiment 2 of this invention. It is a disassembled perspective view of the self-regenerative harmful gas removal filter showing Embodiment 3 of the present invention. It is a schematic block diagram of the air cleaner which shows Embodiment 4 of this invention. It is a schematic block diagram of the air conditioning system which shows Embodiment 5 of this invention.

Explanation of symbols

10, 10A, 10B Self-regenerating harmful gas removal filter, 11 Filter body part, 12 Hygroscopic material, 13 Normal temperature active catalyst, 14 Water film, 15 Through hole, 16 Honeycomb structure, 17 Filter frame, 18 Honeycomb structure Body, 19 Filter frame, 20 Air cleaner, 21 Casing, 22 Air passage, 25 Blower, 30 Air conditioning system, 31 Casing, 34 Blower.

Claims (13)

  A self-regenerating harmful gas removal filter comprising a composite of a hygroscopic material and a normal temperature active catalyst, and having a condensed water film that dissolves water-soluble harmful gas in the air on the surface of the hygroscopic material.   2. The self-regenerative harmful gas removal filter according to claim 1, wherein the filter body portion or the surface layer portion of the passage through which air passes is formed by combining a hygroscopic material and a room temperature active catalyst.   The self-regenerative harmful gas removal filter according to claim 1 or 2, comprising a mixture containing at least a hygroscopic material, a room temperature active catalyst, and an inorganic binder.   The self-regenerating harmful gas removal filter according to any one of claims 1 to 3, wherein the hygroscopic material is a hygroscopic ceramic.   The self-regenerative harmful gas removal filter according to any one of claims 1 to 3, wherein the room temperature active catalyst is a catalyst in which a noble metal and a metal oxide are combined.   4. The self-regenerating harmful gas removal filter according to claim 1, wherein the room temperature active catalyst is a catalyst mainly composed of a metal oxide.   The self-regenerating harmful gas removal filter according to any one of claims 1 to 6, wherein the filter main body portion is formed of a honeycomb structure.   The self-regenerating harmful gas removal filter according to any one of claims 1 to 7, which has a function of removing formaldehyde or acetaldehyde which is a water-soluble harmful gas.   A method for producing a self-regenerating harmful gas removal filter, wherein a hygroscopic material is formed into a honeycomb shape and a room temperature active catalyst is supported on the surface of a passage through which air passes.   The method for producing a self-regenerating harmful gas removal filter according to claim 9, wherein the honeycomb structure is formed into a honeycomb shape using hygroscopic ceramics.   A method for producing a self-regenerating harmful gas removal filter, wherein a mixed paper made of a hygroscopic material and inorganic fibers is formed into a honeycomb shape, and the honeycomb structure is incorporated into a filter frame.   A blower that circulates indoor air is provided in the air passage in the casing, and a hygroscopic material and a normal temperature active catalyst are combined in the air passage. Water-soluble harmful gases in the air are formed on the surface of the hygroscopic material. An air purifier provided with a self-regenerating harmful gas removal filter having a condensed condensed water film. A blower that circulates indoor air is provided in the air passage in the casing, and a hygroscopic material and a normal temperature active catalyst are combined in the air passage. Water-soluble harmful gases in the air are formed on the surface of the hygroscopic material. An air conditioning system comprising a self-regenerating harmful gas removal filter having a condensed water film that dissolves.

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