JPH04346831A - Production of composition having air purifying performance - Google Patents

Abstract

PURPOSE:To obtain an air purifying material and deodorizing filter showing high performance of removing CH3SH by bringing iron or iron alloy into contact with an aq. soln. containing bivalent and/or trivalent iron ion, leaving the iron or iron alloy in an oxidative atmosphere, and allowing the product to adsorb hydrogen sulfide. CONSTITUTION:A fine powder of pig iron is applied on urethane foam and baked in a nonoxidative atmosphere to obtain an iron porous body. This iron porous body is dipped in an aq. soln. of mixture of bivalent and/or trivalent iron ion such as iron (II) sulfate, iron (III) sulfate, iron (II) chloride, iron (III) chloride, etc., and tannic acid, L-ascorbic acid, and sodium hydroxide or calcium hydroxide, etc., as a neutralizer. Then the porous body is dried in air, and allowed to adsorb hydrogen sulfide. Thereby, the obtd. filter has good performance of removing CH3SH while maintaining the performance of removing NH3, (CH3)3N, and H2S.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an air purifying material that purifies contaminated air containing malodorous gases such as NH3 and H2S, and this air purifying material is used, for example, as a household deodorizer. be able to.

0002

[Prior Art] Foul-smelling gases in the air are removed or their discomfort is reduced by adsorption methods using activated carbon, masking methods using other fragrances, and chemical methods that chemically react the odors. ing. However, the adsorption method using activated carbon has the problem that the deodorizing performance deteriorates in a short period of time, and the masking method using other fragrances may give a new unpleasant sensation, so it is not a fundamental solution. A chemical method of causing a chemical reaction includes, for example, a method of oxidizing and decomposing malodorous gases using ozone, but excessive ozone is harmful to the human body and causes new harm. In other words, it is difficult to control the amount of chemical substances that react with the foul-smelling gas, which results in the generation of unnecessary chemical substances, making it difficult to achieve a fundamental solution.

[0003] As a technique for solving these problems, the Journal of the Japan Textile Society (Textiles and Industry) Vol. 42, No. 12 (1
986), pp. 18-26, it is stated that a complex compound obtained by reacting a ferrous compound and ascorbic acid in an aqueous solution has deodorizing power against nitrogen compound-based odor gases. However, according to the findings of the present inventors, this complex compound has a problem in that it has a weak deodorizing power against sulfur compound-based odor gases. Furthermore, according to the findings of the present inventors, this complex compound also had the problem that its deodorizing ability deteriorated in a relatively short period of time.

The present inventors invented a composition in which a reaction product produced by contacting metals such as iron and manganese with ascorbic acid and the like coexists with unreacted iron and manganese, and previously filed a patent application. A patent application was filed under No. 1-280776. This composition can be manufactured at low cost, has extremely low deterioration in air purifying ability, and solves the problems of the prior art.

[0005]

[Problem to be solved by the invention] The present inventor has
This product was created by further extensive research on the composition of No. 280776, and aims to provide a new material with air purifying power through a simpler process. In particular, a deodorizing material that improves the CH3SH removal rate and exhibits CH3SH removal performance over a long period of time is desired.

[0006]

[Means for Solving the Problems] The present invention provides bivalent or trivalent
After bringing iron or an iron alloy into contact with an aqueous solution containing iron ions of valence or both and leaving it in an oxidizing atmosphere to react,
A method for producing a composition having air purifying power, characterized in that the product adsorbs hydrogen sulfide, and
A method for producing a composition having air purifying power, characterized in that an aqueous solution containing valent, trivalent, or both iron ions is produced using iron sulfate, iron chloride, or iron hydroxide; A method for producing a composition having air purifying power, characterized in that at least one organic acid selected from L-ascorbic acid, gallic acid, and tannic acid is present in the aqueous solution, and calcium hydroxide and chloride are added to the aqueous solution. This is a method for producing a composition having air purifying power, characterized in that a basic substance such as sodium or potassium chloride is added to adjust the pH to 2 to 11.

[0007]

[Effect] According to the research of the present inventors, NH3 and (CH3
) Nitrogen gases such as 3N are very well adsorbed to metal complexes and iron oxides, which are reaction products of acids and metals, but H2S gas has weak adsorption power. One solution to this problem is the method of disposing a solid base in a metal complex, as described by the present inventors in Japanese Patent Application No. 63-273195. However, subsequent research revealed that the substances that strongly adsorb acidic gases such as H2S are ferrous hydroxide and ferrous oxide, which are produced when metallic iron is dissolved in an aqueous solution. It is generally known that iron oxide has a decomposition effect on H2S, but the reaction rate is slow at room temperature, so it is necessary to maintain the atmosphere at 200° C. or higher. However, research by the inventors has revealed that ferrous hydroxide and ferrous oxide decompose H2S at an extremely high rate even at room temperature and can be fully utilized as deodorizing materials.

However, in general, when ferrous hydroxide and ferrous oxide are left in the atmosphere, they easily oxidize into magnetite, hematite, goethite, etc., and become H2S at room temperature.
In order to make a practical material, it is necessary to generate ferrous oxide efficiently and prevent the generated ferrous oxide from progressing to oxidation into ferric oxide. A method of stabilizing this is needed. Furthermore, since ferrous oxide alone does not have NH3 removal performance or CH3SH removal performance, conditions for coexistence with other materials are also required.

The reason why the CH3SH removal performance improves as the H2S removal performance improves is thought to be that H in the -SH group has properties similar to H2S. Therefore, it can be inferred that it is effective to effectively generate ferrous hydroxide and ferrous oxide. However, good H2S removal performance means CH3S removal.
The inventors' research has revealed that H performance is not a sufficient condition for good performance. For example, the reaction product obtained by contacting iron with an aqueous L-ascorbic acid solution in air and heat-treating the resulting complex salt and iron coexistence product at 150°C for 24 hours contains ferrous oxide and has extremely good H2S removal performance. is removed from CH3SH
Performance is slightly inferior. As a result of investigating and researching various measures to improve the CH3SH removal performance, we found that the pH of an aqueous solution containing divalent or trivalent iron ions was adjusted to 2 to 11, and the aqueous solution was brought into contact with metallic iron and released in the atmosphere. When left to dry, ferrous oxide is efficiently produced on the iron surface, resulting in a composition with extremely excellent H2S removal performance.

[0010] If the pH is too low, complexes of iron and acid will be produced excessively and form a protective film, which will suppress the formation of ferrous oxide and ferrous hydroxide, reducing the ability to remove nitrogen compound-based odors. However, the ability to remove hydrogen sulfide decreases. On the other hand, if the pH is too high, the formation of ferrous oxide and ferrous hydroxide increases, increasing the ability to remove hydrogen sulfide, but weakening the ability to remove nitrogen compound-based odors. Therefore, in order to have comprehensive air purifying power, it is necessary to adjust the pH to 2-11.

The optimum pH point is the iron ion concentration in the aqueous solution,
It has elements that change depending on the ratio of divalent to trivalent and the composition of the metal iron it comes into contact with. In addition, the optimal pH changes depending on the ambient temperature, humidity, and oxygen partial pressure in which the aqueous solution reacts with metallic iron and ferroalloys, but if the pH is controlled within the above range, the deodorizing ability is practically acceptable. A composition is obtained. As a result of further research on the characteristics of these compositions, it was found that when hydrogen sulfide is adsorbed onto them, the composition changes to a composition with extremely superior CH3SH removal performance compared to the composition before hydrogen sulfide is adsorbed.

[0012] Furthermore, when L-ascorbic acid or tannic acid, etc. is added to the aqueous solution, and calcium hydroxide, sodium hydroxide, etc. are used as a neutralizing agent, iron complexes and ferrous oxide, which improve the NH3 removal performance, are simultaneously released. formation, deNH3,
It has been found that it is possible to produce a material that is excellent in both (CN3)3N and H2S removal performance. We also found that when H2S is adsorbed onto it, the CH3SH removal performance is dramatically improved while maintaining the NH3 removal, (CN3)3N, and H2S removal performance.

Furthermore, the material produced in this way can maintain its performance for a long time due to the coexistence of metallic iron, and forms a structure in which the surface of metallic iron or iron sulfide is covered with iron complexes, iron oxide, and iron sulfide. It was discovered that deodorizing performance could be maintained for a longer period of time by doing so, and the present invention was completed.

[0014] CH3 removal by adsorbing hydrogen sulfide
Although the mechanism of the improvement effect on SH performance has not been fully elucidated, the hydrogen desulfide performance shows almost no deterioration even after repeated use, and the analysis results of the composition after hydrogen sulfide adsorption indicate that the hydrogen sulfide that has been adsorbed It is estimated from the fact that most of the CH3SH has been decomposed and that the residual sulfur content of the deodorizing filter is almost comparable to the sulfur content of the adsorbed hydrogen sulfide. It is considered that this has improved significantly. Next, examples of the present invention will be described.

[0015]

[Example] A porous iron body was produced by applying fine pig iron powder of 10 μm or less to a urethane foam having a mesh roughness of 20 PPI and firing it at 1150° C. for 2 hours in a non-oxidizing atmosphere. Some iron porous bodies contain fine iron sulfide powder of less than 20μ.
Alternatively, a porous iron body containing about 10% sulfur was prepared by mixing fine cobalt oxide powder. The size of one piece was about 90 mm x 80 mm x 10 mm, and the weight was about 40 g.

[0016] The iron porous body is made of ferrous sulfate, ferric sulfate,
It was immersed in an aqueous solution prepared by appropriately mixing ferrous chloride, ferric chloride, tannic acid, L-ascorbic acid, Ca(OH)2 powder, and sodium hydroxide, and was dried in the air for about two weeks. . Two deodorizing filters were manufactured using the same aqueous solution, and the deodorizing performance of each filter was evaluated as is, and the deodorizing performance of each filter was evaluated after adsorbing 100 cc of H2S in advance and leaving it for 24 hours. . Typical examples of specific compounding ratios are shown in Table 1, and the pH of the corresponding aqueous solutions and the results of the deodorizing performance evaluations are shown in Table 2.

[0017]

[Table 1]

[0018]

[Table 2]

[0019] Deodorizing performance is 40 liters in a sealed container.
Install a circulation fan with a blowing capacity of 0 liters/minute.
NH3, (CH3)3N, H2S,
The removal performance of CH3SH was investigated. The initial value is 10 for NH3.
00ppm, (CH3)3N is set to 100ppm, H2S is set to 500ppm, and CH3SH is set to 50ppm.
The residual concentration after 0 to 30 minutes was measured and the removal rate was determined as the deodorization rate. The deodorizing performance of CH3SH was significantly improved by adsorption of H2S, and other deodorizing performances were hardly affected. It was confirmed that the improvement effect continued even in subsequent repeated CH3SH removal tests.

[0020]

Effects of the Invention According to the present invention, air purifiers and deodorizing filters with high CH3SH removal performance can be produced.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the structure of a test device for evaluating deodorizing performance.

[Explanation of symbols]

1: Sealed container, 2: Circulation fan, 3: Deodorizing filter, 4: Gas inlet, 5: Gas sample collection port, 6: Direction of gas circulation.

Claims (4)

[Claims] Claim 1: Bringing iron or an iron alloy into contact with an aqueous solution containing divalent, trivalent, or both iron ions, leaving it in an oxidizing atmosphere to react, and then adsorbing hydrogen sulfide to the product. A method for producing a composition having a characteristic air purifying power. 2. A method for producing a composition having air purifying power, which comprises producing the aqueous solution according to claim 1 using iron sulfate, iron chloride, or iron hydroxide. 3. Production of a composition having air purifying power, characterized in that the aqueous solution of claim 1 or 2 is coexisting with at least one organic acid selected from L-ascorbic acid, gallic acid, and tannic acid. Method. 4. Adding a basic substance such as calcium hydroxide, sodium chloride, potassium chloride, etc. to the aqueous solution of claim 3,
A method for producing a composition having air purifying power, characterized in that the pH is adjusted to 2 to 11.