JPH0597414A - Production of silver-containing crystalline zirconium phosphate - Google Patents

Abstract

PURPOSE:To directly synthesize silver-contg. crystalline zirconium phosphate in one stage and to attain a shortened producing process. CONSTITUTION:A zirconium compd., a phosphoric acid compd. and a silver compd. each contg. no halogen ion as a constituent ion are mixed with water to prepare a reactive slurry. At this time, the silver compd. is added and mixed while keeping the slurry at pH <=6. The prepd. slurry is heated to produce silver-contg. crystalline zirconium phosphate represented by a formula AgXAYZr2(PO4)3 (where A is at least one of alkali metal and ammonium ions, X>0, Y>=0 and X+Y=1).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing silver-containing crystalline zirconium phosphate. The compound produced by the present invention is useful as an inorganic ion exchanger having excellent heat resistance, chemical resistance and weather resistance, and is particularly useful as an inorganic antibacterial agent.

[0002]

2. Description of the Related Art Crystalline zirconium phosphate [AZr
₂ (PO ₄ ) ₃ ] (wherein A represents at least one of alkali metal and ammonia), various synthesizing methods such as a calcination method, a wet method or a hydrothermal method have been proposed. However, in order to obtain a compound having a silver ion as a cation component, there is known a method of once synthesizing a crystalline zirconium phosphate having no silver ion and then subjecting this compound to a post-treatment to carry a silver ion. Only there. As a method of post-treatment, for example, a method is known in which crystalline zirconium phosphate is ion-exchanged and supported by stirring in an aqueous solution of silver nitrate or by mixing with a silver compound and firing.

However, when the post-treatment is carried out by ion exchange, silver ions may be carried only on the surface of the crystalline zirconium phosphate particles, and the carrying of the silver ions may become non-uniform. Was very uneconomical because it was a labor-intensive and time-consuming process.

Further, when crystalline zirconium phosphate, which is a compound having no silver ion, contains ammonium or potassium as a cation, it is difficult to carry the silver ion by post-treatment, and therefore, a carrier for silver ion. There is a problem in that the type of cation of crystalline zirconium phosphate is limited.

On the other hand, silver ions are very unstable ions that are easily reduced, and easily become metallic silver in the presence of light or in the alkaline region and discolor to brown or in the neutral region in the presence of phosphoric acid. Produces silver phosphate and turns yellow.
Further, when silver ions and halogen ions come into contact with each other, silver halide is easily produced. Due to such characteristics of silver ions, a one-step synthesis method of silver-containing crystalline zirconium phosphate capable of supporting silver ions irrespective of the kind of cation of crystalline zirconium phosphate is not known.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to crystalline zirconium phosphate [AZr ₂ (PO ₄ ) free of silver ions.
₃ ] is synthesized and then silver ion is supported on this compound by post-treatment, instead of the conventional two-step reaction synthesis method, the silver-containing crystalline zirconium phosphate [Ag _X A _Y Zr ₂ (PO ₄ ) ₃ ] was synthesized to shorten the manufacturing process, and silver ions were uniformly supported in the obtained silver-containing crystalline zirconium phosphate, and it was difficult to support silver ions by the conventional method. Another object of the present invention is to provide a method for easily obtaining a compound carrying silver ions in crystalline zirconium phosphate having ammonium ions or potassium ions by a one-step reaction.

[0007]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors prepared a reaction slurry by adding a silver compound while maintaining the pH value of the reaction slurry at 6 or less. As a result, they have found that the silver-containing crystalline zirconium phosphate can be directly synthesized in one step, and have completed the present invention. That is, in the present invention, a reaction slurry is prepared by mixing a zirconium compound, a phosphoric acid compound and a silver compound, which do not have halogen ions as constituent ions, and water, wherein the silver compound has a pH value of 6 in the reaction slurry. The method for producing a silver-containing crystalline zirconium phosphate represented by the following formula (1) is characterized in that the reaction slurry is heated while maintaining the following addition. Ag _x A _Y Zr ₂ (PO ₄ ) ₃ (1) (wherein A represents at least one kind of alkali metal ion or ammonium ion, X and Y are each X
> 0, Y ≧ 0, and X + Y = 1. )

The zirconium compound, the phosphoric acid compound and the silver compound used as raw materials in the present invention are compounds having no halogen ion as a constituent ion, and among them, water- or acid-soluble compounds are preferable. Specific examples of the zirconium compound include zirconium sulfate, zirconium oxysulfate and basic zirconium sulfate, zirconium nitrate, zirconium carbonate, zirconium dinitrate oxide dihydrate and the like. Specific phosphoric acid compounds include phosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate and dipotassium hydrogen phosphate. There is. Specific silver compounds include silver nitrate, silver sulfate, and silver carbonate. Of these, silver nitrate is particularly preferable because it has excellent water solubility.

The silver content x of the compound represented by the general formula (1) [hereinafter referred to as compound (1)] is determined by the amount of the silver compound added to the reaction slurry, and the silver in the added silver compound is , Most of the constituent ions of the compound (1).

When A in the compound (1) is either an alkali metal ion or an ammonium ion, a compound containing an alkali metal ion or an ammonium ion may be added and mixed alone, and A in the compound (1) is an alkali. When constituted by both metal ions and ammonium ions, their ratio is determined by the concentration of alkali metal ions in the reaction slurry, the concentration of ammonium ions, and the partition ratio of these ions in compound (1). . Therefore, by appropriately adjusting the concentrations of the alkali metal ion and the ammonium ion in the reaction slurry, it is possible to obtain a crystalline zirconium phosphate compound having a desired ratio of the alkali metal ion and the ammonium ion. For example, when the alkali metal ion in the reaction slurry is made to exist in an excess of about 10 times the stoichiometric amount of A in the target compound (1) and the amount of ammonium ion is changed, the ammonium ion is When it is stoichiometric,
A in the compound (1) produced is almost an alkali metal ion, and when the ammonium ion is doubled in stoichiometric amount of A, A in the compound (1) produced is almost an ammonium ion. On the other hand, when the ammonium ion is between the stoichiometric amount of A and twice the stoichiometric amount, a compound (1) in which an ammonium ion and an alkali metal ion coexist can be obtained as A in the produced compound (1). As a method for supplying an alkali metal ion or an ammonium ion to the reaction system, in addition to a method for supplying a zirconium compound containing an alkali metal ion or an ammonium ion, a phosphoric acid compound or a silver compound as a raw material, another method containing these ions There is also a method of supplying a compound as a raw material. Examples of the other compounds that can be used to adjust the concentration of alkali metal ions and ammonium ions in the reaction slurry are alkali metal salts and ammonium salts having no halogen ion as a constituent ion, and preferred examples thereof include alkali. Examples thereof include sulfates and nitrates of metals and ammonium ions, and more specifically, examples thereof include sodium sulfate, sodium nitrate, potassium sulfate, lithium sulfate and ammonium sulfate. In order to supply the alkali metal salt and / or ammonium salt to the reaction system, one or more water-soluble salts selected from the alkali metal salt and ammonium salt are added to an aqueous zirconium compound solution, an aqueous phosphoric acid compound solution, and a silver compound. It may be added to either the aqueous solution or the reaction slurry.

The silver compound in the present invention must be added and mixed while maintaining the pH value of the reaction slurry at 6 or less. When the pH value of the reaction slurry is higher than 6, silver phosphate or silver hydroxide is produced and colored, and amorphous zirconium phosphate is easily produced, which makes it difficult to produce crystalline zirconium phosphate. There's a problem. The pH value of the reaction slurry during addition and mixing of the silver compound is more preferably maintained at 4 or less.

To adjust the pH value of the reaction slurry, an acid or an alkali may be added to the reaction slurry. Preferred acids include mineral acids such as sulfuric acid and nitric acid, and preferred alkalis are ammonium hydroxide and alkali metal. And the like, and specific compounds of the latter include, for example, sodium hydroxide, potassium hydroxide and lithium hydroxide.

The zirconium compound and the phosphoric acid compound are
These compounds may be used as they are, but it is preferable to use these compounds as an aqueous solution because the reaction ratio of each compound can be more precisely controlled and local heterogeneity of the reaction can be prevented. The mixing ratio of the zirconium compound and the phosphoric acid compound when preparing the reaction slurry,
The ratio of PO ₄ ions to Zr ions is preferably in the range of 1.5 to 2.0 which is the stoichiometric ratio in compound (1).

The order of mixing the above raw materials is not particularly limited, but silver phosphate may be formed when a highly concentrated aqueous solution of a phosphoric acid compound and an aqueous solution of a silver compound are brought into contact with each other. It is preferable to lower the pH and mix the phosphoric acid compound aqueous solution and the silver compound aqueous solution, or to add and mix the phosphoric acid compound aqueous solution and the silver compound aqueous solution to the zirconium compound aqueous solution. In these methods, it is desirable to thoroughly stir the reaction slurry so that the phosphoric acid concentration does not become high and then add and mix the silver compound. In addition, the phosphoric acid compound aqueous solution is added to the zirconium compound aqueous solution, the zirconium compound aqueous solution is added to the phosphoric acid compound aqueous solution, or the phosphoric acid compound and the zirconium compound are simultaneously added and dissolved in water, and then the silver compound aqueous solution is added and mixed. You may. The most preferable mixing order of raw materials for efficiently producing the target compound (1) is as follows. First, a zirconium compound and a phosphoric acid compound are mixed, a pH adjusting agent is added if necessary, and then a silver compound is added. Is.

In the present invention, when the zirconium compound aqueous solution and the phosphoric acid compound aqueous solution are mixed in the reactor, a precipitate is formed, which becomes a slurry state under stirring. The solid content concentration of the reaction slurry is not particularly limited, but the crystallization rate tends to decrease as the concentration increases, while the concentration decreases, the yield per unit volume of the reaction vessel decreases, which is not economical. Therefore, in consideration of the time required for crystallization and the volumetric efficiency, the preferable solid content concentration is 5 to 50.
It is in the range of wt%.

The precipitate in the reaction slurry is further reacted and crystallized by heating the reaction slurry by a hydrothermal method, a wet method or the like to form the compound (1). It is practical to add oxalic acid or the like to the reaction slurry as a complexing agent which has low crystallinity and accelerates the reaction, and as a result, the purity of the compound (1) obtained is lowered. Most preferred is heating by. When the reaction slurry is heated by the hydrothermal method, the reaction slurry is sufficiently crystallized if it is heated at a temperature of 105 ° C. or higher in a hydrothermal state in a closed container. The lower the temperature and the lower pressure, the lower the crystallization rate, and the higher the temperature and the higher pressure, the more difficult it is to economically manufacture because it is easily restricted by the manufacturing equipment. In the state, 105 ℃ or higher is suitable and 120-175 ℃
Is more preferable, and further preferable temperature is 130 to 150 ° C.
And the crystallization is usually completed within 12 to 48 hours.

After the crystalline zirconium phosphate compound is obtained as described above, it is subjected to known solid-liquid separation means such as filtration, decantation, centrifugation and filter-pressing.
The product is separated from the liquid phase, washed, dried and pulverized by a conventional method to obtain the powdery silver-containing crystalline zirconium phosphate represented by the above formula (1).

[0018]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the examples. (Example 1) 21.3 g of zirconium sulfate was added to pure water 30
14 g of sodium dihydrogen phosphate in an aqueous solution dissolved in g
Is added to 20 g of pure water while stirring well. The pH value of the resulting slurry is 20
After adjusting to 2 using a wt% sodium hydroxide aqueous solution, an aqueous solution in which 2 g of silver nitrate is dissolved in 10 g of pure water is gradually added while stirring this slurry. The reaction slurry thus obtained was transferred to a Teflon pressure-resistant container and subjected to hydrothermal treatment at 150 ° C. for 36 hours under saturated vapor pressure. The reaction product was washed with filtered water and dried at 105 ° C. The product was determined to be Ag _0.35 Na by measuring the silver content by powder X-ray diffraction analysis (Fig. 1) and atomic absorption spectrophotometry.
It was identified as a silver-containing crystalline zirconium phosphate represented by a composition formula of _0.65 Zr ₂ (PO ₄ ) ₃ .

Example 2 The reaction was carried out in the same manner as in Example 1 except that the amount of silver nitrate added was 5 g. The product was determined to be Ag _0.95 Na _0.05 Zr by measuring the silver content by powder X-ray diffraction analysis (Fig. 2) and atomic absorption spectrophotometry.
It was identified as a silver-containing crystalline zirconium phosphate represented by the composition formula of ₂ (PO ₄ ) ₃ .

Example 3 The reaction was carried out in the same manner as in Example 1 except that ammonium dihydrogen phosphate was used instead of sodium dihydrogen phosphate. The product was analyzed by powder X-ray diffraction analysis (Fig. 3) and atomic absorption spectrophotometry to determine that the product was Ag _0.3 NH _40.7 Zr ₂ (PO
₄ ) It was identified as a silver-containing crystalline zirconium phosphate represented by the composition formula of ₃ .

[0021]

According to the production method of the present invention, since the silver-containing crystalline zirconium phosphate can be efficiently synthesized in one step, the production process is shortened and the obtained silver-containing crystalline phosphoric acid is obtained. Silver ion is uniformly supported on zirconium, and it is difficult to support silver ion by the conventional method. In crystalline zirconium phosphate having ammonium ion or potassium ion,
A compound supporting silver ions can be easily obtained by a one-step reaction.

[Brief description of drawings]

1 is a powder X-ray diffraction pattern of the dry powder obtained in Example 1. FIG.

2 is a powder X-ray diffraction pattern of the dry powder obtained in Example 2. FIG.

FIG. 3 is a powder X-ray diffraction diagram of the dry powder obtained in Example 3.

Claims (1)

[Claims] 1. A reaction slurry is prepared by mixing a zirconium compound having no halogen ion as a constituent ion, a phosphoric acid compound, a silver compound and water, wherein the silver compound has a pH value of 6 or less in the reaction slurry. A method for producing a silver-containing crystalline zirconium phosphate represented by the following formula (1), which is characterized in that the reaction slurry is heated while being added to and mixed with each other. Ag _x A _Y Zr ₂ (PO ₄ ) ₃ (1) (wherein A represents at least one kind of alkali metal ion or ammonium ion, X and Y are each X
> 0, Y ≧ 0, and X + Y = 1. )