JPH04119913A - Ion exchange treatment of zeolite - Google Patents

Abstract

PURPOSE:To improve weather resistance and whiteness by washing zeolite with an aq. acid soln. before ion exchange treatment. CONSTITUTION:Zeolite is added and dispersed in a prescribed amt. of ion- exchanged water under stirring. A weak acid such as acetic acid and a salt such as sodium acetate as a buffer are dissolved in ion-exchanged water and the resulting aq. soln. adjusted to about pH4-8 is added to the water contg. the dispersed zeolite in 1-100 ratio of the zeolite to the water and the aq. soln. They are stirred for a prescribed time to wash the zeolite. This washing is carried out once or plural times, the washed zeolite is separated with a Buchner filter, etc., and further washed with water to obtain zeolite having high whiteness. This zeolite is dispersed in ion-exchanged water under stirring, an aq. soln. of a metallic salt such as AgNO3 is added and they are stirred for a prescribed time. The treated zeolite is separated, washed with ion-exchanged water and dried at 100-500 deg.C to obtain a product with supported metal ions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of ion-exchanging zeolite, and a zeolite ion-exchanged according to the method.

[Conventional technology] Zeolite has unique pore diameter, surface electric field, ion exchange ability,
It has adsorption and separation capabilities, and is attracting attention as an extremely useful functional material. Zeolites can also support other metal ions through ion exchange, and zeolites with specific metal ions supported exhibit functions ascribed to the metal ions in addition to the zeolite-specific functions. .

For example, French Patent Application No. 1061158, Japanese Patent Publication No. 63-54013, JP-A No. 63-260810 and JP-A-63-270764 disclose that Antimicrobial compositions containing zeolites have been described. Furthermore, catalytic action can be added by supporting a transition metal such as nickel on zeolite.

[Problems to be Solved by the Invention] JP-A-63-260810 and JP-A No. 63-270764 describe in detail the conditions for supporting each metal ion, such as the concentration of metal salt during ion exchange, pH, etc. Although it is disclosed, even if ion exchange of zeolite is performed under these conditions, the product zeolite may become black or its weatherability whitening may be reduced.Also, even if ion exchange is performed under the same conditions, The quality and characteristics of the product zeolite may differ depending on the time of manufacture.

Decreased whitening and weathering resistance not only pose a serious problem when used in fields where aesthetic appearance is required, such as in fibers and polymers. It may have an adverse effect on the effect.

The presence of impurities in zeolite is considered to be one of the causes of the decrease in white discoloration and weathering resistance of zeolite, and the variation of the quality of product zeolite from production to production. According to the present inventor's findings, commercially available synthetic and natural zeolites are contaminated with various impurities. For example, when each of the A-type zeolites from four companies was dispersed in distilled water and left to stand, the anions contained in the supernatant were analyzed. Carbonate ions were detected, and in some cases nitrite and bromine ions were also detected. When producing synthetic zeolite, sodium aluminate is used as one of the raw materials, but commercially available synthetic zeolite also contains unreacted sodium aluminate. Furthermore, when two types of natural zeolites were analyzed, iron and calcium were detected in both, and magnesium was also detected in one. As described above, various zeolites contain various impurities.

Some of these impurities may react with ions in the metal salt solution during ion exchange and adversely affect the product zeolite. For example, the presence of sodium aluminate in a zeolite dispersion may increase the pH of the dispersion and cause deposits of metal hydroxides, metal oxides, etc. on the zeolite surface.

If calcium ions are present, deposits such as CaCO2 may be formed on the zeolite surface depending on the type of metal salt used for ion exchange and the pH during ion exchange.

To specifically explain the case in which silver ions are supported on zeolite, even if the pH during ion exchange is in the acidic region, the presence of halogen ions causes AgX (X=CI
! , B r, I) are formed on the zeolite, reducing the whitening and weathering resistance of the product zeolite. Similarly, the presence of sulfide ions causes deposits such as A g 2 S to precipitate and blacken the product zeolite. Combinations of silver ions and halogens, as well as metal ions such as silver, copper, and mercury, and sulfide ions have a particularly strong tendency to form deposits, and simply controlling the conditions for ion exchange treatment cannot completely prevent the formation of these deposits. cannot be prevented.

Even if the above-mentioned deposits are not formed, if aluminate ions are present, the metal ions to be supported on the zeolite may be consumed in the formation of aluminate, and the amount of metal ions supported on the zeolite may be becomes difficult to control. In order to obtain a product zeolite with high white discoloration and high weatherability white discoloration with a constant quality every time it is produced, it is desirable to perform an ion exchange treatment on the zeolite from which such impurities have been removed. However, although some zeolites currently on the market have specified potassium, calcium, and iron contents, zeolites have been removed from impurities such as halogens and sulfide ions to the extent that they do not have a negative effect on ion exchange. is not commercially available. An object of the present invention is to provide a method for producing a product zeolite with excellent white discoloration and weather resistance using ordinary commercially available zeolite.

[Means for Solving the Problems] The present invention provides a method for supporting metal ions on zeolite by ion exchange, in which, prior to ion exchange treatment,
This method is characterized by washing zeolite with an aqueous acid solution.

Further, the present invention is a zeolide produced according to the above method.

Here, an important requirement of the present invention is to wash the zeolite with an aqueous solution containing an acid (hereinafter sometimes referred to as an acid solution) before subjecting the zeolite to the ion exchange treatment. If the ion exchange treatment is performed without washing, or if the ion exchange treatment is performed after simply washing with water or hot water, it is difficult to obtain a product zeolite with high white discoloration and weather resistance, which is the objective of the present invention. On the other hand, as shown in the following examples, when ion exchange is performed after washing with an acid solution according to the present invention, a product zeolite with significantly increased white discoloration and weathering white discoloration resistance can be obtained. In particular, when washing is carried out under conditions such that the pH of the zeolite dispersion falls within the range of about 4 to 8, or when the aqueous solution contains a buffering agent, very high white discoloration and It is possible to obtain a zeolite that has weathering resistance and whitening.

Acid-containing aqueous liquids are aqueous solutions of various inorganic and/or organic acids. Examples of acids include hydrochloric acid, sulfuric acid,
Inorganic acids such as nitric acid and phosphoric acid, as well as formic acid, acetic acid, oxalic acid,
Organic acids such as tartaric acid can be used. An inorganic acid and an organic acid may be used in combination, or two or more types of inorganic acids or organic acids may be used in combination. Although various conventional acids can be used in the present invention as described above, weak acids such as acetic acid, formic acid, tartaric acid, adipic acid, and boric acid are particularly preferred. Since weak acids act more slowly on zeolites than strong acids, there is less risk of undesirably attacking the zeolite during the cleaning process of the present invention, and therefore impurities trapped in the zeolite framework (this As long as the substances are confined within the zeolite framework, there is little risk of adverse effects during ion exchange), but they will not leach out from the zeolite framework. Further, when a weak acid is added to a zeolite dispersion, unlike a strong acid, the viscosity of the dispersion increases only slightly and foaming occurs, and the washing operation can be easily performed. Water is generally used as the solvent, but a small amount of an organic solvent may also be used.

In a preferred embodiment, a buffer is added to the acid solution. This not only makes it easier to adjust the pH, but also reduces fluctuations in liquid pH and reduces the risk of attack on the zeolite.

The advantages of using buffers are particularly pronounced when cleaning synthetic zeolites. Since synthetic zeolite contains a large amount of alkaline components as impurities, it is desirable to use a sufficient amount of acid during cleaning. From the point of view of ease of cleaning operation and economy, it is preferable to reduce the amount of acid solution as much as possible; however, in this case, using a sufficient amount of acid increases the acid concentration and lowers the pH of the zeolite. Particle erosion is caused. However, when an acid solution or a buffer is contained, the liquid pn does not decrease and erosion of the zeolite by the acid can be prevented. here,
A "buffer" is a reagent for making a buffer solution. Typically combinations of various weak acids and their salts, such as acetic acid and sodium or potassium acetate, tartaric acid and sodium or potassium tartrate, phosphoric acid and sodium or potassium phosphate, lactic acid and sodium or potassium lactate, etc. Other known combinations include a combination of a strong acid and a salt of a weak base, such as a combination of hydrochloric acid and sodium acetate, or a combination of a strong acid and a salt of a strong acid, such as a combination of hydrochloric acid and sodium chloride. ing. There are no particular limitations on the buffer that can be used in the present invention, and various known buffers can be used. A mixture of two or more types of buffering agents may be used. When a weak acid is used for cleaning according to the present invention,
A buffer solution can be created by adding a salt of the weak acid. Preferably, a combination of a weak acid and its salt is used as a buffering agent in the present invention. In particular, when a weak acid is used to prepare the acid solution, it is preferable to use a salt of the weak acid as a buffering agent.

The acid solution of the present invention may also contain a surfactant as an optional component. Furthermore, if necessary, a desulfurizing agent, a dehalogenating agent, etc. can also be used in combination. It is also possible to use an oxidizing agent such as hydrogen peroxide solution.

The washing treatment method is arbitrary and can be carried out under various conditions depending on the type of zeolite, the metal to be supported, the purpose of use, etc. To give an example of preferable processing conditions, p
A solid-liquid ratio of 1:1 to 1:100 with amounts of acid and buffer such that H is about 4 or more and less than about 8, especially about 4.5 to 7.5.
, especially within 1 hour at a ratio of about 1:2 to 1:20, usually from 10 to
Wash by stirring for about 30 minutes. Here, pi of the dispersion liquid
(is more preferably maintained within the above-mentioned preferred range until the end of the cleaning process. Optionally, heating may be performed. It is usually sufficient to perform the cleaning operation - times, but it may be performed multiple times. .

When the cleaning operation is performed multiple times, the cleaning operation does not have to be the same each time, and it is sufficient that one of the cleaning operations is performed using the cleaning method according to the present invention. This is especially true when dechlorinating agents, desulfurizing agents, etc. are used, or when the compounds used during cleaning may react with the compounds used during ion exchange to form deposits (e.g. when using hydrohalic acid for cleaning). , and then when silver ions are supported by ion exchange), it is preferable to perform washing with water or hot water as the final step of the washing treatment.

Following the washing treatment as described above, the zeolite is subjected to an ion exchange treatment. There are no particular restrictions on the ion exchange treatment method, and various conventional methods can be used. As an example, in the case where zeolite supports metal ions having antibacterial effects such as silver, copper, zinc, etc., it is preferable to set the pH during ion exchange to the acidic side and to lower the concentration of the metal salt solution. Ions such as silver and copper may form deposits when the concentration of the metal salt and the pH of the solution increase during ion exchange. Even when performing ion exchange with metal ions other than these, the concentration of the metal salt solution used, p
Those skilled in the art will be able to easily determine conditions such as H depending on the properties of the desired product zeolite.

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, cleaning may be performed using a small amount of distilled water or an acid solution. 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. Further, the ion-exchanged zeolite may then be subjected to treatments such as heating under a hydrogen stream, immersion in an acidic or alkaline solution, and hydrophobization with paraffin, wax, or the like.

If washing treatment with an acid solution is performed prior to ion exchange treatment according to the present invention, a product zeolite with improved white discoloration and weathering resistance can be obtained unless the subsequent ion exchange treatment is inappropriate. Therefore, it is suitable for use in fields requiring high white discoloration and weather resistance, for example, when mixed into fibers, polymers, etc. Furthermore, according to the present invention, the amount of deposits formed on the product zeolite can be reduced, so it is possible to obtain a zeolite with improved functions such as zeolite adsorption, antibacterial properties, and catalytic activity. Furthermore, it is possible to obtain a product zeolite of almost constant quality every time it is produced, without being affected by impurities contained in the zeolite used as a raw material. In particular, when a buffer is used in combination, the zeolite skeleton is not eroded, so the yield is improved, and there are advantages in that impurities in the zeolite skeleton are not mixed into wastewater.

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to the following examples.

[Examples] The white discoloration and weather resistance white discoloration in the Examples and Comparative Examples are Hunter white discoloration measured using a TC-1 colorimeter manufactured by Tokyo Denshoku Kogyo. The test specimen used for the measurement of white discoloration was made by drying the zeolite sample at 105°C for 2 hours, and then
It was made by filling a plastic ring with a diameter of 1.0 mm in diameter and solidifying it by applying a pressure of 10 tons using a press, and had a smooth surface.

For weather resistance white discoloration, the above test specimen after measuring white discoloration was
Referring to the method specified in SL-0842, 4
The measurements were taken after irradiation with arc lamp light for 0 hours.

Example 1. 2a, 3. Comparative Example 1, 0.6 kg of 2A-type zeolide was added to ion-exchanged water5. A solution of various amounts of acetic acid (approx. 100% purity) diluted with 0.51% of ion-exchanged water was added to the mixture, and the mixture was stirred and dispersed in 500% water at room temperature for 1 hour.
Stir at rpm. After solid-liquid separation using a Bluffnal filtration device, ion-exchanged water was poured from the top of the filtration device for washing.

After washing, the zeolite is rehydrated with ion-exchanged water5. Disperse 30 g of silver nitrate in OA at room temperature under stirring at 500 rpm and 2.0 g of ion-exchanged water! ! The solution was added over about 20 minutes. After continuing stirring for another 20 hours, solid-liquid separation was performed using a Brafnal filtration device, washed with ion-exchanged water, dried at 130° C. for 4 hours, and pulverized to obtain a product. For comparison, we performed the same ion exchange treatment as above after performing the above cleaning treatment without adding acetic acid (washed with water) (Comparative Example 1), and performed the same ion exchange treatment as above without performing the cleaning treatment. A zeolite carrying silver ions was produced from the same 8-type zeolide by the following procedure (Comparative Example 2).

The white discoloration of each zeolite was measured in the
Shown in the table. It is clear that according to the invention, zeolites ion-exchanged after washing with an acid solution have a higher white discoloration than those ion-exchanged after washing with water or without washing.

Table 1 Amount of acetic acid 1) pH of dispersion 2) White discoloration 3) Comparative example 1 0
Approximately 11 64.9 Example 1 25
Approximately 7.5 84.9 Example 2a 50
Approximately 5.5 85.4 Example 3100 Approximately 4
．． 5 84.81) Units 2 g2) Initially washed3) Hunter Whiteness Example 2b 50.0 g of acetic acid (100% purity) and 68.5 g
5. of sodium acetate. A buffer aqueous solution having a pH of 4.8 was prepared by dissolving OI in ion-exchanged water. 0.6 in this
kg of type A-zeolide was gradually added over 20 minutes,
Washing was performed at room temperature for 30 minutes while dispersing at a stirring speed of 500 rpm. The pH of the zeolite dispersion after washing was 5.
6, which was only 0.8 higher than before dispersing zeolite. Next, after performing solid-liquid separation using a Brafnal filtration device, 2. ion-exchanged water is poured from the top of the filtration device. OA was added and washed with water.

After washing, the zeolite was poured into ion-exchanged water again under stirring at room temperature and 500 rpm. Dispersed in Ol, 30.0 g
2. Add silver nitrate to ion-exchanged water. Approximately 2 ml of solution dissolved in OI
Added over 0 minutes. After further stirring at room temperature for 20 hours, solid-liquid separation was performed using a Brafnal filtration device, washed with ion-exchanged water, dried at 130° C. for 4 hours, and pulverized to obtain a product. Although concentrated hydrochloric acid was added to the filtrate after the ion exchange treatment, no white precipitation of AgCl occurred, indicating that almost all of the silver ions were supported on the zeolite.

White discoloration of the obtained product zeolite (solder was 87.5).

Examples 4 to 6, Comparative Example 3 0.6 kg of A-type zeolide was added to 5.0 kg of ion-exchanged water. Of
V under stirring at 500 rpm. A solution of 60 g of various acids dissolved in 0.51 g of ion-exchanged water was added over 20 minutes, and then heated to 80°C and heated to 30°C.
Stir for a minute. The pH of each dispersion at the end of acid addition was between about 4.5 and 5.5. After cooling to room temperature, solid-liquid separation was performed using a Brafnal filtration device, washed with ion-exchanged water, dried at 130° C. for 2 hours, and pulverized.

The zeolite (approximately 0.6 kg) that has been subjected to the above washing treatment is washed with ion-exchanged water. Disperse 30 g of silver nitrate in 2 ml of ion-exchanged water, O
After adding the solution in 100 ml over 20 minutes, stirring was continued for an additional 20 hours. Solid-liquid separation was performed using a Brafnal filtration device, washed with ion-exchanged water, and then heated at 130°C for 4 hours.
It was dried for a while and ground into a product.

For comparison, the same A-type zeolide was subjected to the same ion-exchange treatment as above, except that it was washed without adding acid (the pH when the zeolite was dispersed in ion-exchanged water was approximately 11). An operation was performed to perform the following.

The white discoloration and weather resistance of each zeolite are shown in Table 2 along with the type of acid used during the cleaning treatment. It is clear that according to the invention, zeolites that are ion-exchanged after washing with an acid solution have higher whitening and weathering whitening than those that are ion-exchanged after washing with water.

Table 2 Acids used Whitening 1) Weathering whitening 1) Example 4 Acetic acid 92.2 84.9 Example 5 Oxalic acid 89.8 81.6 Example 6
Tartaric acid 89.2 80.4 Comparative example 3 Not used 72.0 51.21) Hunter white discoloration
2) Water washing Example 7 50,0g acetic acid (100% purity) and 68.5g
5.g of sodium acetate. A buffer aqueous solution having a pH of 4.8 was prepared by dissolving it in ion-exchanged water. 0 in this.
After adding 6 kg of Type A zeolide over 20 minutes, the mixture was heated to 80° C. and washed for 30 minutes while being dispersed at a stirring speed of 500 rpm. Next, after performing solid-liquid separation using a Buchner filtration device, 2. ion-exchanged water is poured from the top of the filtration device. OL was added and washed with water.

After washing, the zeolite was poured into ion-exchanged water again under stirring at room temperature and 500 rpm. Dispersed in Ol, 30.0 g
2. Add silver nitrate to ion-exchanged water. The solution dissolved in Ol
Added over 0 minutes. After further stirring at room temperature for 20 hours, solid-liquid separation was performed using a Buchner filter, washed with ion-exchanged water, dried at 130° C. for 4 hours, and pulverized to obtain a product. Although concentrated hydrochloric acid was added to the filtrate after the ion exchange treatment, no white precipitate of AgC1 was produced, indicating that almost all of the silver ions were supported on the zeolite.

The white discoloration of the obtained product zeolite was 92.9, and the weather resistance white discoloration was 88.7 (both Hunter white discoloration), which are higher values compared to Example 4 despite the smaller amount of acid used. Met.

Reference Example This example shows that the erosion of zeolite particles can be suppressed by the combined use of a buffer.

2. OM (120g/A) acetic acid aqueous solution (pH 2.4
) and stirred for 20 hours, this zeolite was dissolved.

On the other hand, even if a small amount of A-type zeolide was added to a buffer solution (pH 5.1) containing acetic acid at a concentration of 2.0M and sodium acetate at a concentration of 4.0M and stirred for 20 hours, zeolite particles remained No particular changes were observed.

Claims (1)

[Scope of Claims] 1. A method for supporting metal ions on zeolite by ion exchange, which comprises washing the zeolite with an aqueous acid solution prior to the ion exchange treatment. 2. The method according to claim 1, characterized in that when washing the zeolite, the initial pH of the dispersion of the zeolite in an aqueous acid solution is within the range of about 4 to 8. . 3. The method according to claim 1 or 2, characterized in that a weak acid is used as the acid. 4. Claims 1 to 3, wherein the aqueous solution contains a buffering agent.
The method described in any one of the paragraphs. 5. The method according to any one of claims 1 to 4, wherein the metal ion is a silver ion. 6. Zeolite ion-exchanged by the method according to any one of claims 1 to 5.