JPH03270708A - Deodorizing filter - Google Patents

Abstract

PURPOSE:To enhance the adsorbing capacity to a sulfur compound by supporting a hydrated ferric oxide particulate powder having a stripe like microstructure and formed into a bamboo leaf shape having a specific aspect ratio on a synthetic resin foamed body having open voids. CONSTITUTION:Alkali carbonate is added to an aqueous ferrous salt solution in an amount of one equivalent or more with respect to a ferrous salt to be reacted with the ferrous salt and oxygen gas is passed through the formed FeCO3-containing aqueous solution to oxidize FeCO3 to obtain a hydrated ferric oxide particulate powder. A synthetic resin foamed body having air permeable open voids is impregnated with a slurry containing the aforementioned hydrated ferric oxide particulate powder having a stripe like microstructure and showing a bamboo leaf shape having a long axis diameter of 0.2-1.0mum and an aspect ratio of 3-10 and a binder. The adhesion amount of the slurry is controlled by squeezing the foamed body by a roller and hydrated ferric oxide particles are bonded to the surface of the foamed body or infiltrated into the foamed body to prepare a deodorizing filter.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a deodorizing filter that extremely well adsorbs sulfur compounds such as hydrogen sulfide and mercaptans.

[Conventional technology]

Odors from factories, poultry farms, pig farms, human waste treatment plants, garbage dumps, etc. can occur outdoors, while odors from toilets, closets, and sewage rooms can easily occur indoors and disturb a comfortable living environment. drugs are needed. In addition, body odor is trapped in closed spaces such as nursing homes, submarines, and automobiles, so it is necessary to take measures using deodorizers.

For this reason, both in the East and the West, methods have been widely used to reduce discomfort with a so-called pleasant scent, such as the use of perfumes, scented oils, or "burning incense." Recently, physical adsorption methods using activated carbon and reactive adsorption methods using chemical substances have been put into practical use. The former takes advantage of the large specific surface area of activated carbon, while the latter converts the malodorous components themselves into other chemical substances, which requires large equipment and is used as a measure to prevent malodors in factories, etc. It's being used.

[Problem to be solved by the invention]

However, activated carbon has a small adsorption capacity and is not durable because it re-releases. On the other hand, as reaction adsorbents for chemical substances, those that use iron in combination with ascorbic acid and those that immobilize hypochlorous acid are well-known, but the former is expensive, and the latter generates toxic chlorine, so it is not suitable for use. There are limits to Furthermore, since these deodorizing agents are in the form of granules or powder, they are difficult to handle for specific purposes.

For example, most of the deodorizers used in forced ventilation type odor removal equipment and air purification equipment installed to improve work and living environments are in the form of granules, so they have a large ventilation pressure loss and require a large amount of fan power. .

Therefore, when applying to these devices, it is necessary to make the deodorizer layer as thin as possible to reduce pressure loss, and to sandwich granular deodorizers such as activated carbon or zeolite between nets to make handling easier. A method of creating a type of filter was proposed and has already been put into practical use.

In addition, filters in which activated carbon powder is supported on non-woven fabric or porous synthetic resin foam have been developed and have already been put into practical use.
No. 3 and JP-A No. 51-11085> All of them support activated carbon, and therefore have low deodorizing effects.

On the other hand, it is known that hydrous ferric oxide particles have excellent adsorption ability for sulfur-based malodorous substances and sulfur compounds such as sulfur oxides. As a prior art document using hydrous ferric oxide particles as a deodorizing agent for sulfur compounds, there is
Examples include JP-A No. 6-20688 and JP-A-50-60492.

However, in the case of acicular hydrated ferric oxide particles, especially the finer they are, the particles stick together, overlap, and agglomerate, resulting in a dense powder with a small porosity and a high density of air. There is a problem in that the permeability becomes poor and the contact area with sulfur compounds such as sulfur-based malodorous substances and sulfur-based oxides in the atmosphere or gas becomes small, resulting in a decrease in adsorption capacity.

Although the pure T-iron oxyhydroxide particles and the burr-shaped hydrated ferric oxide particles shown in the above-mentioned publications have excellent adsorption ability for sulfur compounds due to their particle morphology, do not have.

In order to solve such conventional drawbacks, the present inventors have repeatedly conducted experimental studies and found that the axial ratio (major axis diameter/ Short axis diameter〉3～
It was discovered that hydrated ferric oxide particles having the shape of a bamboo leaf of No. 10 exhibit an extremely excellent deodorizing effect on malodorous substances such as hydrogen sulfide and mercaptan. ~136902).

The present invention further develops the above-mentioned proposal and aims to provide a deodorizing filter that uses the previously proposed deodorizing agent and has an excellent odor removal and hanging effect.

[Means to solve the problem]

The present invention has demonstrated that a carrier formed by impregnating and adhering the previously proposed hydrous ferric oxide particles together with a binder to a synthetic resin foam consisting of continuous pores is excellent as a deodorizing filter for removing malodorous substances. Heading: The present invention has been completed.

That is, the present invention provides a synthetic resin foam with a long axis diameter of 0.5 mm having a streak-like ultrafine structure in a synthetic resin foam consisting of continuous air-permeable pores.
A slurry of hydrated ferric oxide particles with a bamboo leaf shape of 2 to 1.0 μm and an axial ratio (major axis diameter/minor axis diameter) of 3 to 10 and a binder was impregnated, and the amount of slurry adhered was determined. This is a method for producing a deodorizing filter by controlling the foam by squeezing it with a roller, and then attaching and filling the hydrous ferric oxide particles to the surface or inside of the foam.

[Effect]

First, the most important point in the present invention is that it has a striped ultrafine structure, has a long axis diameter of 0.2 to 1.0 μm, and an axial ratio (major axis diameter/short axis diameter) of 3 to 10. When hydrated ferric oxide particles exhibiting a The fact is that

Furthermore, since the hydrous ferric oxide particles used in the present invention are rounded particles that resemble bamboo leaves, microscopically, the particles are less likely to stick together and overlap, resulting in a large porosity. It also has good air permeability, so the contact area with gas is large. Therefore, the hydrated ferric oxide particles used in the present invention efficiently adsorb sulfur-based malodorous substances in gas, and are an extremely excellent material as a deodorizing agent.

Particles with a major axis diameter of 1.0 μm or more are unsuitable because of their small specific surface area, and particles with a major axis diameter of 0.2 μm or less are too fine and cause agglomeration between the particles, which is undesirable. Further, particles with an axial ratio of 3 or less have a small characteristic of bamboo leaf-like particles having a striped ultrafine structure, and particles with an axial ratio of 10 or more are undesirable because they become nearly acicular.

The hydrous ferric oxide particles used in the present invention can be easily obtained by the following manufacturing method. That is, adding 1 equivalent or more of alkali carbonate to the ferrous salt aqueous solution,
It is obtained by reacting to obtain FeCO3, and then passing an oxygen-containing gas into the resulting aqueous solution containing FeCO3 to cause an oxidation reaction.

In the above manufacturing method, as the ferrous salt aqueous solution, a ferrous sulfate aqueous solution, a ferrous chloride aqueous solution, etc. are used. When adding alkali carbonate to a ferrous salt aqueous solution to obtain FeCO3,
Alkali carbonate and alkali hydroxide may be used in combination. As the alkali carbonate, sodium carbonate, potassium carbonate, ammonium hydrogen carbonate, etc. are used alone, or when these and alkali hydroxide are used in combination, sodium hydroxide, potassium hydroxide, ammonium hydroxide, etc. are used. Further, depending on the case, ripening may be performed in a non-oxidizing atmosphere. The pH of the solution during the oxidation reaction is 7-11. pH
If the pH is below 7 or above 11, it is not possible to obtain hydrated ferric oxide having a bamboo leaf shape.

The reaction temperature during oxidation is preferably 30 to 80°C. This is because if the temperature is below 30°C, hydrous ferric oxide particles having a bamboo leaf shape cannot be obtained, and if the temperature is above 8°C, granular black precipitates are mixed.

The oxidation means is carried out by aerating an oxygen-containing gas (for example, air) into the liquid, or while stirring with the aerated gas or mechanical operation. The precipitate thus obtained is usually filtered, washed with water, dried, and ground into fine powder by conventional methods.

At this time, drying is carried out at 150°C or lower, preferably at 120°C for 5
It is desirable to do this for about an hour. When dried at a temperature of 150° C. or higher or by heating for a long time, oxidation progresses, crystal growth occurs, the specific surface area decreases, and the adsorption capacity decreases.

Note that when used in the present invention, it is not necessarily necessary to dry or crush it, and it may be used in the form of a slurry or cake after washing.

Next, this hydrated ferric oxide particles (hereinafter referred to as deodorizing material)
A method for supporting the filter base material on the filter base material will be explained. First, the filter base material used in the present invention is a synthetic resin foam with a three-dimensional network structure consisting of continuous pores, of which the cell range (number of holes per inch) is preferably 17.
It is preferably 23 or less. Considering the ventilation resistance as a filter, it is better to have a larger pore diameter, but the basis weight (g/+
n2) decreases, the contact area with the gas decreases accordingly, and the adsorption performance deteriorates.

On the other hand, if the pore size is small, the ventilation resistance will be large, which is not preferable as a filter. A caking agent is required to support the deodorizing material on this filter base material, and starch, CMC, PVA, rubber latex, etc. can be used as these materials. Among these, starch is a hydrous oxidized Latex has the effect of improving the bonding between ferric iron particles and the adhesion to the filter base material, so it is preferable to use both in combination.

Next, the amount of the deodorizing material supported on the filter base material and the blending ratio with the binder (starch, latex) in the present invention will be explained.

First, regarding the amount of the binder added to the deodorizing material, it is preferable that the amount of starch is in the range of 5 to 10 parts by weight per 100 parts by weight of the deodorizing material. Starch is effective in bonding between hydrous ferric oxide particles, which are deodorizing materials, and when supported on a filter, the filter itself becomes hard, reducing the likelihood of the supported material peeling off or falling off due to vibration or impact. When starch is used in this way, the adhesion force is strengthened, but if it is added in excess of what is necessary, the adsorption performance will deteriorate, which is not preferable. Latex also has the effect of strengthening the adhesion to the filter base material. The amount of latex added is 2.5 to 5 parts by weight per 100 parts by weight of the deodorizing material.
Parts by weight ranges are preferred. If the amount of latex added is less than this range, the adhesion to the filter base material will be weak, and if it is too much, the adsorption capacity for malodorous substances will decrease, which is not preferable.

Next, a method of supporting the filter base material will be explained.

The above-mentioned binder and water are added to the deodorizing material (hydrated ferric oxide particles) used in the present invention to form a slurry, and a synthetic resin foam is immersed in this slurry, so that the inside of the foam is sufficiently impregnated with the slurry. Thereafter, excess slurry is squeezed out using a rubber roll, and a predetermined amount of deodorizing material is adhered and carried on the inside and surface of the foam. In this case, the supported amount can be arbitrarily selected by the degree of squeezing by the rollers, but if it is squeezed too much, the supported amount will decrease and the adsorption capacity will decrease. Conversely, if the aperture is insufficient, excess deodorizing material remains filled inside the foam, leading to an increase in ventilation resistance. Therefore, the supported amount should be determined depending on the field of application of the deodorizing filter from both adsorption performance and ventilation resistance.For example, if ventilation resistance is 2m+aH-0 (wind speed 1
If the target is m/66 (as) or less, the supported amount is preferably in the range of 20 to 40 g/l.

This supported amount refers to the weight of the slurry after it has been squeezed out and dried.

The deodorizing filter thus obtained can be cut into any size depending on the field of application and used as it is for removing bad odors.

[Example 1] 3.53 mol/j in the reaction vessel! of Na2CL aqueous solution 201 and then 1.0 mol/j! Fe5 of
L aqueous solution 301 was added and mixed, and Fe
Obtained CO3. Air was bubbled through the resulting aqueous solution containing FeC0- at a temperature of 40° C. at a rate of 1,501 liters per minute for 4.0 hours to carry out an oxidation reaction and produce yellowish brown precipitated particles. Note that the pH of the reaction solution during air ventilation was 9.6.

The produced yellow-brown precipitated particles were separated by filtration, washed with water, dried, and pulverized by a conventional method to obtain 2.61 kg of yellow-brown particle powder (a).

As a result of X-ray diffraction, it was confirmed that the obtained yellowish brown particles (a) were hydrated ferric oxide. The results are shown in FIG. As shown in the enlarged electron micrograph (X150.000) shown in Fig. 2, the yellowish brown particles (a) obtained had an average major axis diameter of 0.25 μm and an axial ratio (major axis diameter/short axis diameter). It was confirmed that the particles were composed of hydrous ferric oxide particles having a bamboo leaf shape and a striped ultrafine structure with an axial diameter of 8 and a specific surface area of 106 m'/g.

On the other hand, hydrated ferric oxide (b) with different particle forms.

(C) was prepared by the following method.

0.68 mol/i Fe5On aqueous solution 801 was placed in the reaction vessel, and then 4.32 mol/i Na0)
101 of an aqueous solution was added and mixed, and then the reaction was carried out for 4 hours at a temperature of 40° C. while blowing air at a rate of 1301 per minute to form yellowish brown precipitated particles. Note that the pH of the reaction solution during air ventilation was 5.8 to 4.0.

The produced yellow-brown precipitated particles were filtered, washed with water, dried and pulverized in a conventional manner to obtain 1.83 kg of yellow-brown particle powder (5).

As a result of X-ray diffraction, it was confirmed that the obtained yellowish brown particles (b) were hydrated ferric oxide. The results are shown in FIG. As shown in the enlarged electron micrograph (xlOO,000) shown in Figure 4, the yellowish brown particles (b) obtained have an average long axis diameter of 0.3 μm and an axial ratio (long sleeve diameter/short axis diameter). ) 10. It was confirmed that the material was composed of acicular hydrated ferric oxide particles with a specific surface area of 95 m'/g.

In yet another method, 1.57 mol/l in the reaction vessel
Pe5o and aqueous solution 51 were added and the temperature was adjusted to 30°C. Then, 4 tons of air was blown at a rate of 201 per minute.
0.21 of a nol/1 ammonia aqueous solution (the amount of ammonia corresponds to 5.0% with respect to the total amount of Fe) was added to obtain an aqueous solution containing yellowish brown particles. The pH at this time was about 3.

Subsequently, the reaction temperature was adjusted to 80° C. while blowing air at a rate of 201/min, and an ammonia aqueous solution of 4[IIol/1] was added to maintain the pH in the range of 2.5 to 4.0 to continue the oxidation reaction for 5 hours. went.

The yellow-brown precipitated particles thus obtained were filtered, washed with water, dried, and pulverized in a conventional manner to obtain 629 g of yellow-brown particle powder (C).

As a result of electron microscopy, it was confirmed that the yellowish brown particles (C) were made of burr-shaped hydrated ferric oxide particles. Moreover, this particle powder has an average diameter of 0.
．． 9. ua+, and the specific surface area was 85 m1/g.

Using the three types of hydrous ferric oxide particle powders with different particle forms obtained in this way and activated carbon powder as a comparative material,
For each 100 parts by weight of these, 400 parts by weight of a 2.5 wt% starch solution (corn starch) and latex (
Showa Denko: PBTALUS 300) 5 parts by weight were added, and further 20 parts by weight of water were added and thoroughly stirred and mixed to prepare a slurry. Each slurry is made of synthetic resin foam (urethane foam; Brideston Deaf Everlight Scotto "MR-20 (number of cells 17 to 23))" consisting of interconnected holes.
After thoroughly impregnating the inside of the foam with the slurry, the excess slurry is squeezed out with a rubber roller and dried at 60°C to form the attached deodorizing filters a', b/,
A deodorizing filter impregnated with c/ and activated carbon was obtained.

Cut each of these filters into a size of 60 x 60, stack two of each, and set them in the circulating adsorption evaluation device shown in Figure 5.
Next, test gas containing hydrogen sulfide with a concentration of 5 pptn 1001
A Tetra Vac containing 100 ml was attached to the apparatus, and the test gas was subsequently circulated through ventilation at a flow rate of 23 Q 1 /cnirI. The circulating test gas was sampled at regular intervals, and the residual concentration of hydrogen sulfide in the test gas was measured by gas chromatography. The results are shown in Table 1.

The hydrogen sulfide adsorption capacity values shown in Table 1 are as follows:
The residual concentration after minutes is shown. From Table 1, filter a' carrying bamboo leaf-shaped hydrated ferric oxide particles (a) has needle-shaped or burr-shaped hydrated ferric oxide particles (b), (
It was confirmed that the hydrogen sulfide adsorption performance was superior to filters b' and c' carrying C). Furthermore, it can be seen that the hydrogen sulfide adsorption performance is superior when compared to filters that support activated carbon.

Table 1 [Example 2] 1 of the bamboo leaf-shaped hydrated ferric oxide particles (a) obtained in Example 1
00 parts by weight, starch and latex were blended as shown in Table 2, and water was added to prepare a slurry having a slurry concentration of 20 to 22 wt%. Urethane foam of the same size as in Example 1 was immersed in this, and after squeezing out the excess slurry with a rubber roller, it was dried at 60°C.
I got 0.

Each of the obtained deodorizing filters was cut into a size of 60 x 60, and the weight of each two pieces was measured, and then the hydrogen sulfide adsorption performance was measured in the same manner as in Example 1.

When the supported amount was determined from the weight of the filter, it was in the range of 1.0 g to 1.2 g for each filter sample. (2 pieces of 60X80X5 tmm) Furthermore, in order to examine the adhesion of the supported material to the filter, the pole tapping method (
Place a 6° x 60 x 5 t filter sample in an 80φ sieve, place 10 12φ alumina balls on top of it, close the lid, and use a shaker to hit the sample with the balls (70 times/30 minutes). The rate of peeling was measured.

These results are also shown in Table 2.

The H2S adsorption performance values in Table 2 indicate the residual concentration 20 minutes after the start of passing the H2S-containing gas at a concentration of 5 PPff1 through the filter, as in Example 1.

From Table 2, deodorizing filters 1 and 2 have good H2S adsorption ability, but peeling is large, and deodorizing filters 5.6 and 8.
It can be seen that although No. 10 has good adhesion, the adsorption performance of No. 112S is poor.

[Example 3] 1 of the bamboo leaf-shaped hydrated ferric oxide particles (a) obtained in Example 1
A slurry containing 0.00 parts by weight, 10 parts by weight of starch, and 2.5 parts by weight of latex was prepared, impregnated into urethane foam, and squeezed with a rubber roller to produce deodorizing filters with different supported amounts as shown in Table 3. 11 to 15 were obtained. Each of the filters was cut into a size of 60×60, and the H and S adsorption performance was measured in the same manner as evaluated in Example 1. At the same time, the ventilation resistance of the filter was measured and the results are also shown in Table 3.

As in Example 1, the H2S adsorption performance was expressed as the residual concentration after 20 minutes.

In addition, as a comparative example, slurry was prepared using the same formulation for activated carbon, and filters (16 to 18
) was measured for H2S adsorption performance and ventilation resistance, and the results are also shown in Table 3.

1 Fig. 2 (Magnification +50.(X)0) [Effects of the Invention] The deodorizing filter according to the present invention has excellent adsorption ability for sulfur-based malodorous substances in gas, so it is particularly effective at absorbing malodors such as hydrogen sulfide and mercaptan. It is ideal as a deodorizing filter for air purification equipment, etc.

[Brief explanation of drawings]

Figure 1 is an X-ray diffraction diagram of the hydrous ferric oxide particles used in the present invention obtained in Example 1, and the peak in the figure is α
-Fe001 (215?I) is an enlarged electron micrograph (8150,000) showing the particle morphology. It is an X-ray diffraction diagram of a hydrous ferric oxide particle powder in the form of acicular particles prepared as a comparative example of the invention, and the peak in the figure is α-Fe00)1. FIG. 4 is an enlarged electron micrograph (×100,000) showing the particle morphology. I (51!l is a flow diagram of the device used to evaluate the H, S adsorption performance of the deodorizing filter. Figure 3 2θ Figure 4 (Amour 100,000) Flat Bottom 2nd July 2S Day 5th figure

Claims (1)

[Claims] Long axis diameter 0.2 to 1.0 with a streak-like ultrafine structure
It is characterized by being made by supporting a hydrated ferric oxide particle powder in the shape of a bamboo leaf with an axial ratio (major axis diameter/minor axis diameter) of 3 to 10 μm on a synthetic resin foam consisting of continuous pores. A deodorizing filter.