JPH04108608A - Method for ion-exchanging of zeolite - Google Patents

Abstract

PURPOSE:To suppress thickening or foaming of a zeolite suspension and to easily exchange ions in order to deposit metal ions on the zeolite by ion exchange method by controlling pH of the zeolite suspension by using a weak acid to a specified acid region. CONSTITUTION:When metal ions are deposited on zeolite by ion exchange method, pH of the zeolite suspension during ion exchanging is controlled to about 4.0-6.5 by using a weak acid. The weak acid is preferably acetic acid, formic acid, oxalic acid, tartaric acid, adipic acid, citric acid, etc. By using silver, copper or zinc as metal ions, an antifungal zeolite can be prepared.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for supporting metal ions on zeolite by ion exchange, and a method for supporting metal ions, particularly metal ions having antibacterial activity, on zeolite. Regarding zeolite.

[Prior Art and its Problems] A known technique is to support metal ions on zeolite through ion exchange, and roughly add the function of metal ions to the original function of zeolite. For example, French Patent No. 1061158, Japanese Patent Publication No. 63-54013@,
JP 63-260810 and JP 6327076
Publication No. 4 describes an antibacterial composition containing zeolite ion-exchanged with antibacterial ions such as copper, zinc, and silver. Also known is a technique in which zeolite supports a transition metal such as nickel to impart catalytic action.

Ion exchange of zeolite is carried out by dispersing zeolite in an aqueous liquid containing metal ions to be supported, as described in the above publication. However, the present inventor has discovered that the synthetic zeolite dispersion exhibits alkalinity with a pH of about 10 or higher. It often exhibits strong alkalinity with a pH of 11 or higher. Under such high DH conditions, precipitation of insoluble compounds of the metal to be ion-exchanged may occur. For example, if the pH of a solution containing silver ions is about 9.5 or higher, Ag2O
or precipitate. If such deposits are formed, the antibacterial properties and other functions of the zeolite product may be reduced.

[Means for solving the problem 1: As a method of preventing the formation of the above-mentioned deposits during ion exchange of zeolite, the pN of the zeolite dispersion is adjusted to about 9.5 or less by adding a mineral acid such as hydrochloric acid or nitric acid. (Precipitates are almost never formed at a pH of 9.5 or less). However, the present inventor has found that when these mineral acids are used to adjust the pH of the zeolite dispersion to about 9 or less, the zeolite dispersion thickens and becomes difficult to manipulate. At a pH below about 7, especially below 6, the degree of thickening is slightly less than at pH about 7 to 8, or intense foaming occurs for a while, so when ion exchange is carried out under these conditions, In preparation for the foaming of the zeolite dispersion, the amount charged per batch must be kept small and a large reaction vessel must be used. Another drawback is that ion exchange treatment cannot be performed while the dispersion is foaming, which increases the processing time.

The inventors have found that ion exchange treatment can be easily carried out when a weak acid is used as the acid for adjusting l)H.

That is, the present invention provides a method for supporting metal ions on zeolite by ion exchange, in which the pH of the zeolite dispersion during ion exchange is adjusted to about 4.0 to 9 using a weak acid.
, 5.

The present invention also provides a zeolite on which metal ions, particularly metal ions having an antibacterial effect, are supported according to the above-described method.

Here, the use of a weak acid as the acid for adjusting the ρ■ of the zeolite dispersion is an important requirement of the present invention. This suppresses thickening and foaming of the zeolite dispersion, and facilitates ion exchange. This was completely unexpected.

For example, when 2N nitric acid or 2N acetic acid is added little by little to distilled water in which zeolite is dispersed, thickening of the dispersion and considerable foaming are observed when nitric acid is added, but a small amount is observed when acetic acid is added. There is only foaming, no thickening occurs, and l)H of the zeolite dispersion becomes almost constant quickly. The reason for this is that when a strong acid is added to the immersion liquid in which zeolite is dispersed, the DH of the immersion liquid decreases locally, and a part of the zeolite is rapidly eroded (
For example, 8-type zeolides are rapidly attacked at pH values below about 4), whereas when using a weak acid such as acetic acid, the local drop in pH of the immersion solution is small, so rapid decomposition of the zeolite hardly occurs. it is conceivable that.

Therefore, the added weak acid is not used to decompose the zeolite, and the treatment of the present invention proceeds gently. Furthermore, since weak acids act more slowly on zeolite than strong acids, there is less risk of undesirably attacking the zeolite during ion exchange treatment.

Zeolites in the present invention include all natural and synthetic zeolites. Zeolites are generally aluminosilicates with a three-dimensionally developed skeletal structure, and generally have a ratio of X M 2 / on the basis of 8 ρ203. 0-A
It is expressed as l2O2·y S + 02ZH20. M
represents an ion-exchangeable metal ion, usually a monovalent or divalent metal, and n is its valence. x, y and 2 indicate the coefficient of metal oxide, the coefficient of silicon dioxide and the number of water of crystallization, respectively. Zeolite has composition ratio, pore diameter,
A wide variety of zeolites with different specific surface areas are known, including natural zeolites such as anarsin, chabasite, clinoptilolite, erionite, phojasite, mordenite, and philipsite, A-type zeolide, and X-type zeolite.
Examples include synthetic zeolites such as type zeolide, Y-type zeolite, and mordenite. Preferred among these are synthetic A-type zeolides, X-type zeolides, Y-type zeolites, and synthetic or natural mordenites.

The shape of the zeolite is preferably in the form of powder particles, and the particle size may be appropriately selected depending on the application. When the antibacterial zeolite of the present invention is mixed into thick molded objects, such as various containers, pipes, granules, or thick denier fibers, the particle size is several microns to several tens of microns or several microns. 10
The particle size may be 0 micron or more, but when forming into -5 fine denier fibers or films, the smaller the particle size is, the better; for example, in the case of clothing fibers, it is preferably 5 micron or less, particularly 2 micron or less.

There are no particular restrictions on the metal ions supported on zeolite.
Iron, zinc, copper, tin, silver, vanadium, tungsten, nickel, barium, molybdenum.

antimony, chromium, calcium, magnesium.

It is possible to use any metal ion that can be ion-exchanged, such as manganese, lithium, aluminum, titanium, gallium, germanium, etc. Moreover, two or more types of metal ions can also be used. Therefore, the metal ions to be supported on the zeolite may be selected depending on the intended use. To specifically explain the production of antibacterial zeolite by way of example, metal ions having antibacterial properties, preferably silver, copper and/or zinc ions, are used.

l)H of the zeolite dispersion during ion exchange is approximately 4 to 9
．． It is preferable to keep it within the range of 5. A pH higher than about 9.5 may result in deposits depending on the type of metal, while a pH below about 4 attacks the zeolide.

A particularly preferred pH range is about 5-9. If ion exchange is performed at a pH within this range, the formation of deposits and the erosion of zeolite can be almost completely suppressed.

1) Examples of weak acids used to adjust H include, but are not limited to, organic acids such as acetic acid, formic acid, oxalic acid, tartaric acid, adipic acid, and citric acid, and inorganic acids such as phosphoric acid. . Particularly preferred acids are organic acids such as acetic acid, formic acid, oxalic acid, tartaric acid, adipic acid, citric acid and the like. In the present invention, inorganic acids and organic acids can also be used together,
Also, two or more types of inorganic acids or organic acids may be used in combination. Some of these weak acids react with metal ions in the solution! ! However, these salts are usually soluble and do not pose any particular disadvantage in the present invention.

The ion exchange treatment method is arbitrary. When carrying out the ion exchange reaction in a batch method, the zeolite material may be immersed in a solution of metal salts.

Here, the concentration of the metal salt solution is preferably maintained in a diluted state (eg, 0.3M or less for silver salts, 1M or less for copper salts, particularly 0.05M or less). When the pH of the zeolite dispersion is adjusted to about 4.0 to 9.5, particularly about 5 to 9, and the concentration of the metal salt solution is lowered, the formation of deposits can be more completely suppressed.

In order to increase the metal content in the zeolite material, the number of batch treatments may be increased. On the other hand, when treating a zeolite material using a column method using a solution of metal salts, the desired metal-zeolide can be easily obtained by filling an adsorption tower with the zeolite material and passing the salt solution through it. . Further, when ion-exchanging two or more types of metal ions, each ion may be supported simultaneously or each may be supported separately. When two or more types of metal ions are supported separately, there is no particular restriction on the order.

After ion exchange, the zeolite is usually separated from the liquid, washed, and dried. Separation can be performed by any method such as filtration or decantation. The cleaning treatment method is arbitrary, and for example, the zeolite may be washed by dispersing it in distilled water under stirring, or it may be washed by pouring distilled water from above the filtration device. The drying treatment is preferably carried out at a temperature of 100 to 500°C under normal pressure or reduced pressure. Particularly preferred drying conditions are 100 to 350°C under reduced pressure.

The zeolite on which metal ions are supported in this manner may be subjected to various treatments such as rough treatment, immersion treatment in an acid or alkaline solution, and heat treatment under a hydrogen stream.

According to the method of the present invention, ion exchange treatment can be easily carried out in a shorter time than conventionally without damaging the zeolide excessively, and moreover, it is possible to reduce the amount of acid used for pH adjustment.

The zeolite of the present invention is similar to zeolite in which metals are supported by the conventional ion exchange method, and even when used in liquids or water containing various other metal ions, metals do not elute from the zeolite and the metals are supported. The functions of the metal ions that have been made are maintained for a long period of time.

Therefore, it is suitable for use in a water system, for example, in the case of antibacterial zeolite, it is suitable for applications such as algae prevention, and for use as an additive to water-based paints. The antibacterial zeolite of the present invention can be widely applied to antibacterial paints, coatings, tile joints, etc.

In addition, the zeolite of the present invention, like zeolite ion-exchanged by conventional methods, also has the original functions of zeolite, so it has the functions of supported metal ions and the original functions of zeolite, such as moisture absorption and adsorption effects. It is possible to use both together. Furthermore, it is also possible to coexist with other functional substances to exhibit a combined function of the above effects and other functions. Other functional substances include activated carbon and silica gel. In the case of activated carbon, the deodorizing and adsorption effects are enhanced, and in the case of silica gel, the moisture absorption effect is enhanced.

Furthermore, the zeolites of the present invention do not have a gritty feel, unlike those ion-exchanged using strong acids.
It has the same slippery feel as the synthetic zeolite from which it is made.

In other words, the surface of the synthetic zeolite is not roughened.

Next, the present invention will be further explained with reference to examples, but the present invention is not limited to the following examples.

[Example] Example 1 Acetic acid (concentration > 98%) was added to a dispersion (solid-liquid ratio 1:1) in which 200 g of 8-type zeolide was dispersed in 20 (7!) of ion-exchanged water (solid-liquid ratio 1:1) with stirring at 10 rpm. was added one drop at a time from a bilulet every minute, and the viscosity of the dispersion at a specific l)H was measured. To measure viscosity, Tokyo Keiki Seisakusho B
A type viscometer was used. Separately, replace acetic acid with concentrated nitric acid (
The same operation was carried out using a standard of about 16 liters. The results are shown in Table 1. It is clear that the viscosity of the dispersion increases markedly when nitric acid is used, whereas the viscosity decreases when acetic acid is used. In addition, when concentrated nitric acid was used, the zeolite dispersion foamed due to the addition of acid, and severe foaming was observed especially in the pi range of 6.7 to 7.5, but when acetic acid was used, foaming was observed. was only slightly recognized.

Example 2 1.0% of ion-exchanged water was placed in a reaction tank with a capacity of 2g and equipped with a stirring device.
Add Il, synthetic zeolite (A type zeolite) 0.5
Ky was added and dispersed by stirring at 25° C. and a stirring speed of 500 rpm. A mixture of ion-exchanged water and various amounts of 6M acetic acid aqueous solution 300IX112 was added to this over 10 minutes, and the mixture was stirred roughly for 30 minutes. Next, silver nitrate 4.59
A solution prepared by dissolving 200 d of ion-exchanged water was added over 1 hour, and after the addition, a zeolite dispersion (solid-liquid ratio 1:
The temperature in step 3) was raised to 60° C., and the mixture was further stirred for 5 hours. Solid-liquid separation is performed using a Bützfner filtration device, and 1.0. l! After washing the zeolite by gradually adding ion-exchanged water, the obtained zeolite particles were
It was dried at 0° C. for 4 hours and pulverized appropriately using a pharmacopoeia mortar.

The obtained zeolite-AQ was filled into an aluminum ring with an inner diameter of 45 #, and a test molded body was obtained by applying a pressure of 10 tons using a press machine, and then measured using a colorimetric colorimeter (Model TC-1, manufactured by Tokyo Heavy Industries, Ltd.). Hunter varus (HW) was measured.

The amount of 6M acetic acid aqueous solution used, l)H immediately after addition of the silver nitrate aqueous solution to the zeolite dispersion and the viscosity of the dispersion at that time, and the Hunter varus of the obtained zeolite-Act are shown in Table 2. Shown below.

Comparative Example The same operation as Example 2 was carried out except that 6M11 was used instead of 6M acetic acid. However, the same p as the corresponding example
More 6M nitric acid was required to reach the H value. Table 2 shows the amount of acid solution used, the I)H and viscosity of the dispersion immediately after the addition of the aqueous silver nitrate solution, and the Hunter's varus of the product zeolite-Ag.

As shown in Table 2, no thickening of the zeolite dispersion was observed in the ion exchange of Example 2 using acetic acid. On the other hand, in the comparative example using nitric acid, a large increase in viscosity was observed. There is a significant difference in the viscosity of the olide dispersion when acetic acid is used as the acid and when nitric acid is used as the acid. Furthermore, when acetic acid was used according to the present invention, the zeolite dispersion only slightly foamed at around pH 6.8, and stirring and filtration were easy, whereas when nitric acid was used, 1) At 87.0 or below, significant foaming of the zeolite dispersion was observed.

Furthermore, from the comparison of Hunter's varus in Table 2, it is clear that zeolite ion-exchanged in the presence of acetic acid according to the method of the present invention.
It is clear that Aq has better product varus than ion exchanged with nitric acid at similar pH.

Procedural amendment May 31, 1991

Claims (1)

[Claims] 1. In a method of supporting metal ions on zeolite by ion exchange, the pH of the zeolite dispersion during ion exchange is adjusted to about 4.0 to 9.5 using a weak acid. A method characterized by: 2. Process according to claim 1, characterized in that the metal ions are metal ions selected from the group consisting of silver, copper and zinc. 3. Process according to claim 1 or 2, characterized in that the weak acid is selected from the group consisting of acetic acid, formic acid, oxalic acid, tartaric acid, adipic acid and citric acid. 4. The pH of the zeolite dispersion during ion exchange is approximately 5.0.
Claim 1, characterized in that it is within the range of ~9.0.
The method according to any one of Items 1 to 3. 5. Zeolite ion-exchanged by the method according to any one of claims 1 to 4.