JP2604939B2 - Dechlorinating agent and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dechlorinating agent, and more particularly to a dechlorinating agent for chemically decomposing and removing chlorine dissolved in water and a method for producing the same.

[0002]

2. Description of the Related Art In general, chlorine dissolved in tap water, industrial water and other waters may adversely affect the human body and other living organisms due to its sterilization, bleaching and oxidizing effects, and may be a hindrance in production. Various methods have been adopted as means for removing chlorine dissolved in tap water or other water. Conventionally, as a typical dechlorination method, a method of physically adsorbing free chlorine with activated carbon has been widely used, but dissolved chlorine and dissolved organic acids in water are simultaneously adsorbed on activated carbon, and trihalomethane is generated in the activated carbon. Might be.

On the other hand, as a chemical dechlorination method, there is a method using sodium thiosulfate. However, this method can only be used as a dechlorinating agent for aquarium fish water. There is a problem that thiosulfate ions remain therein, and the thiosulfate ions act as a reducing agent, which adversely affects fish.

As another chemical dechlorination method, for example, Japanese Patent Application Laid-Open No. 54-105844 discloses the use of calcium sulfite as a dechlorinating agent, which makes it easy to handle and can be used for a long time. Therefore, it has been proposed that calcium sulfite powder is kneaded with a binder, molded and used as a tablet.

[0005]

However, although calcium sulfite dihydrate is a crystalline powder, it is a fine powder like the hemihydrate and anhydrous salts and has poor moldability. A binder must be used, and the surface of the calcium sulfite powder particles is inevitably covered with the binder, and the contact area between calcium sulfite and water is reduced.
There was a problem that the dechlorination effect was reduced. Moreover, tablets have a large amount of binder, so that it is difficult to obtain a dechlorinating agent having good water permeability.

Accordingly, an object of the present invention is to provide a dechlorinating agent having a large dechlorination action and good water permeability.

[0007]

According to the present invention, as a result of research on calcium sulfite as a dechlorinating agent, when producing calcium sulfite, in the initial stage, scaly giant particles are produced as an intermediate product. Giant particles are aggregates of a large number of primary particles of calcium sulfite hemihydrate having a prismatic crystal structure, and have a large average particle size and specific surface area, and calcium sulfite dihydrate, hemihydrate and anhydrous salt. Focusing on the fact that it has a higher activity and is more excellent in moldability as compared with the above, as a means for solving the above-mentioned problems, a slime-like coagulation consisting of primary particles of calcium sulfite hemihydrate having a prismatic crystal structure is used. The aggregate is used as a main component of the dechlorinating agent.

The dechlorinating agent according to the present invention is an agglomerate in which a large number of primary particles of calcium sulfite hemihydrate having a prismatic crystal structure as a main component are aggregated, and the purity of the agglomerate is 90% or more. Are preferable, and the specific surface area is ² to 20 m ^2.
/ G and an average particle size of 3 to 30 μm.

Since the agglomerate is a giant particle having an average particle diameter of 3 to 30 μm, it can be used as it is as a dechlorinating agent for water purifiers, bathing agents, water for ornamental fish and other waters. When the water-insoluble binder is added and granulated, the surface of the aggregate is not covered with the binder because the aggregate is in a scaly form, and therefore, it can be granulated while maintaining its activity. . In this case, the addition amount of the water-insoluble binder is preferably 1 to 20% by weight. The crushing strength of spherical or granular particles is 0.2 to
10 kg is preferred.

According to the present invention, the dechlorinating agent is
A calcium compound aqueous solution and an alkali metal sulfite aqueous solution are mixed with stirring and reacted at a temperature of 15 to 45 ° C. for a predetermined period of time to form a scaly mixture of primary particles of calcium sulfite hemihydrate having a prismatic crystal structure. Can be produced by producing an aggregate, filtering and washing the aggregate, and granulating the aggregate with a binder. In addition, as a granulation method, any known method such as extrusion molding, a marmerizer method, a bread granulation method, and a rolling granulation method may be employed.

The primary particles of calcium sulfite hemihydrate constituting the aggregate produced by this method have a prismatic crystal structure, a width of 0.05 to 0.5 μm and a length of 10 to 5 μm.
0 μm.

As the binder, any binder can be used as long as it is stable in water and insoluble in water. Typical examples thereof include ethyl cellulose and other cellulose derivatives, and methacrylic copolymers.

[0013]

The dechlorinating agent according to the present invention oxidizes calcium sulfite as a main component by chlorine dissolved in water and changes into insoluble calcium sulfate. Dechlorination can be performed without mixing sulfite ions into water. The dechlorinating agent according to the present invention is an intermediate product whose main component is highly active, i.e., a giant scoop-shaped average particle size of 3 to 30 μm in which primary particles of calcium sulfite hemihydrate of prismatic crystals are aggregated. An aggregate having a specific surface area of ² to 20 m ²
/ G and remarkably larger than ordinary calcium sulfite dihydrate, hemihydrate and anhydrous salt, the number of reaction points with chlorine dissolved in water is increased, and the crystal structure is It contributes to improvement.

The purity of calcium sulfite is preferably 90% or more. This is because if it is less than 90%, the dechlorination ability is reduced.

The dechlorinating agent according to the present invention has a special physical shape in which the main component is a scaly shape. However, since the dechlorinating agent behaves as a giant particle in which small primary particles are gathered, the dechlorinating agent is easy to handle and process. In addition, even when granulated into a spherical or granular form with a water-insoluble binder, microscopic pores are formed between the surface of the dechlorinating agent particles and the aggregated particles, so that the particles are removed. Does not impair chlorine capacity.
Furthermore, the relatively small diameter of the dechlorinating agent, which is spherical or granular, contributes to the improvement of water permeability.

[0016]

Example 1 28 g of calcium chloride dihydrate was added to 28
It is dissolved in 1 ml of ion-exchanged water to prepare a 1.74 mol / l aqueous solution of calcium chloride.
Dissolve 9.2 g in 400 ml of ion-exchanged water and add 1 mol / l
To prepare an aqueous solution of sodium sulfite. Stir and mix the calcium chloride aqueous solution and the sodium sulfite aqueous solution,
The reaction was carried out while maintaining the liquid temperature of 30 ° C.
After a lapse of minutes, the reaction product was separated by filtration, washed, and then dried to obtain a crystalline powder of calcium sulfite hemihydrate.

[0017]

Example 2 74 g of calcium hydroxide was dissolved in 258 ml of ion-exchanged water to prepare a 3.89 mol / l aqueous solution of calcium hydroxide.
It was dissolved in 00 ml of ion-exchanged water to prepare a 1.46 mol / l aqueous solution of potassium sulfite. The aqueous solution of calcium hydroxide and the aqueous solution of calcium sulfite were stirred and mixed, and reacted while maintaining the liquid temperature at 30 ° C. After a lapse of 30 minutes from the start of the reaction, the reaction product was separated by filtration, washed and dried to obtain a crystalline powder of calcium sulfite hemihydrate.

[0018]

[Comparative Example] 76.5 g of calcium chloride dihydrate was 281 m
dissolved in ion-exchanged water to prepare a 1.74 mol / l aqueous solution of calcium chloride.
2 g was dissolved in 400 ml of ion-exchanged water to prepare a 1 mol / l sodium sulfite aqueous solution. The calcium chloride aqueous solution and the sodium sulfite aqueous solution are stirred and mixed,
The reaction was carried out for 240 minutes while maintaining the liquid temperature of ° C. Then
The reaction product was separated by filtration, washed and dried to obtain a calcium sulfite hemihydrate crystal powder.

The specific surface area of each calcium sulfite hemihydrate obtained in the above Examples and Comparative Examples was measured by the BET method, and the particle size distribution was determined. Table 1 shows the obtained results.

[0020]

[Table 1] Example 1 Example 2 Comparative Example Specific surface area (m ² / g) 7.9 5.3 10.7 Particle size distribution <5 μm 8.66 10.24 59.69 (vol%) 5-10 μm 34.64 47. 93 30.21 10-20 μm 42.34 34.14 9.4 20-30 μm 9.82 6.14 0.7 30 μm <4.54 1.55 0 Average particle size (μm) 12.7 10.67 4 .94

Each of the crystal powders obtained in Examples and Comparative Examples was observed with an electron microscope, and the results shown in FIGS. 1, 2 and 3 were obtained. 1 is an electron micrograph of the calcium sulfite hemihydrate obtained in Example 1, FIG. 2 is an electron micrograph of the calcium sulfite hemihydrate obtained in Example 2, and FIG. 4 is an electron micrograph of the obtained calcium sulfite hemihydrate.

From the results shown in FIGS. 1 to 3, the calcium sulfite hemihydrates of Examples 1 and 2 obtained by stopping the reaction in the course of the production process were formed by aggregation of primary particles to form giant particles. On the other hand, it can be seen that the comparative example in which the calcium sulfite formation reaction was completed was present in the form of primary particles.

Further, a solution prepared by dissolving 200 g of ethyl cellulose in 100 ml of ethyl alcohol was added to the calcium sulfite hemihydrate powder obtained in Example 1, and the solution was granulated in a bread, and then passed through a sieve for 0.5 to 1.5 mm. Dechlorination agent
(Crushing strength: 1.4 kg). This dechlorinating agent was filled in a commercially available water purifier in place of activated carbon, attached to a water tap, and passed through at a rate of 10 to 13 liters per minute. The colorimetric method using an ortho-tolidine reagent (detection limit concentration 0.01 pp
In m), no free chlorine was recognized from the purified water.

A solution prepared by dissolving 200 g of ethyl cellulose in 800 ml of ethyl alcohol was added to the calcium sulfite hemihydrate powder obtained in Example 1, and the mixture was kneaded, extruded and granulated, and then passed through a sieve. 0.5-1.
A 5 mm dechlorinating agent (crush strength: 0.9 kg) was obtained. This dechlorinating agent was filled in a commercial water purifier in place of activated carbon, attached to a water tap and passed through at a rate of 10 to 13 liters per minute.In the above colorimetric method, free chlorine was purified from purified water. Not detected.

[0025]

As is apparent from the above description, the dechlorinating agent according to the present invention is composed mainly of giant particles in which primary particles of calcium sulfite hemihydrate are aggregated, and reduces and removes chlorine by a chemical reaction. Therefore, there is no danger of producing trihalomethane as in the case of using activated carbon as a dechlorinating agent, and since the reaction product is water-insoluble calcium sulfate, it is used as a filter medium for water purifiers or a dechlorinating agent for water for ornamental fish. Even when used, there is no danger that ions harmful to the human body, fish and other organisms are eluted in water as in the case where sodium thiosulfate is used as a dechlorinating agent, and about 10 times less than activated carbon.
Double the dechlorination effect is obtained. In addition, when the dechlorinating agent of the present invention is used as a bath agent or a component thereof, chlorine dissolved in water, which causes atopic dermatitis, can be effectively removed.

The dechlorinating agent according to the present invention has good handling and processability since it has a specially shaped aggregate as a main component, and is a spherical or granular particle. It is possible to reduce the amount of the agglomerate, and therefore, it is possible to granulate without impairing the activity of the agglomerate.

[Brief description of the drawings]

FIG. 1 is a photograph showing the crystal structure of calcium sulfite hemihydrate obtained by the method of the present invention,

FIG. 2 is a photograph showing the crystal structure of calcium sulfite hemihydrate obtained by the method of the present invention,

FIG. 3 is a photograph showing a crystal structure of calcium sulfite hemihydrate obtained by a conventional method.

Claims (5)

(57) [Claims] The present invention is characterized in that a main component is a scaly aggregate formed of primary particles of calcium sulfite hemihydrate having a prismatic crystal structure, and the aggregate is bound with a water-insoluble binder of 1 to 20% by weight. A dechlorinating agent comprising spherical or granular particles. 2. The aggregate comprises calcium sulfite hemihydrate having a purity of 90% or more, and has a specific surface area of 2 to 20 m.
The dechlorinating agent according to claim 1, wherein {2} / g and the average particle size are 3 to 30 µm. 3. The dechlorinating agent according to claim 1, wherein the crushing strength of the particles is 0.2 to 10 kg. 4. The dechlorinating agent according to claim 1, wherein the water-insoluble binder is a binder selected from the group consisting of a cellulose derivative and a methacrylic copolymer. 5. A mixture of a calcium compound aqueous solution and an alkali metal sulfite aqueous solution, which are reacted at a temperature of 15 to 45 ° C. to form a coagulated coagulate consisting of primary particles of calcium sulfite hemihydrate having a prismatic crystal structure. A method for producing a dechlorinating agent, comprising: stopping the reaction at the time when an aggregate is formed; filtering and washing the aggregate; and adding 1 to 20% by weight of a water-insoluble binder to perform granulation.