JPH08268708A - Inorganic cation exchanger - Google Patents

Abstract

PURPOSE: To obtain an inorg. cation exchanger having a high cation exchange capacity and a high rate of cation exchange and suitable for use as a water treating agent, a water softening agent, a of a detergent, etc. CONSTITUTION: This inorg. cation exchanger is made of a crystalline alkali metallic silicate hydrate represented by the compositional formula xM2 O.(1-x) Na2 O.ySi2 -zH2 O [where M is an alkali metal other than Na, (x) is a figure of 0.01-1, (y) is a figure of 3-5 and (z) is a figure of 1-20].

Description

Detailed Description of the Invention

[0001]

The present invention relates to a novel inorganic cation exchanger, more specifically, a high cation exchange capacity and a high cation exchange rate, which are useful as water treatment agents, water softening agents, detergents and the like. The present invention relates to an inorganic cation exchanger composed of a crystalline hydrous alkali metal silicate.

[0002]

2. Description of the Related Art Hardness components contained in tap water are clothes,
When washing dishes, bathtubs, toilets, etc., it combines with surfactants contained in detergents and fatty acids contained in dirt,
It has long been known that it produces a water-insoluble salt and significantly reduces the cleaning effect. In order to prevent this, a substance that traps or blocks the hardness component in tap water, that is, a water softening agent is usually added to the cleaning agent. For example, sodium tripolyphosphate has long been used in detergent compositions for clothing. However, due to the problem of eutrophication in rivers, a search for alternative substances for sodium tripolyphosphate has been conducted, and A-type zeolite, which is one of synthetic zeolites, is generally used as an inorganic cation exchanger for water softeners. became.

On the other hand, in recent years, with the recent trend toward compact household cleaning agents, it has been demanded that cleaning agent components be highly functional.
There is a demand for a highly functional inorganic cation exchanger capable of changing the water softener to A-type zeolite. For this purpose,
"Inorganic cation exchanger function" is mainly evaluated by its ability to capture calcium ions, which is the main hardness component in tap water, that is, cation exchange capacity. At the same time, the inorganic cation exchanger is used as a water softener. When used, it is necessary to quickly capture or block the coexisting surfactant or fatty acid in dirt and the hardness component in tap water before binding, so the rate of capturing this calcium ion (positive It is also important to increase the ion exchange rate).

Various studies have been conducted in order to enhance the function of this inorganic cation exchanger, and up to now, a water softener composed of δ-type sodium disilicate (Japanese Patent Publication No. 41116/1989), periodic tables IIa, IIb, IIIa, IVa or V
A water softener composed of an alkali metal silicate to which a metal belonging to Group III has been added (JP-A-5-184946) has been proposed. However, δ-type sodium disilicate is disadvantageous in that it is water-soluble and, when dispersed in water, its crystal structure changes and its calcium ion-trapping ability is lower than that of A-type zeolite. Alkali metal silicates are also produced by firing,
It is converted to an anhydride, which inevitably lowers the ion exchange rate. In order to improve the ion exchange rate, a crystalline alkali metal silicate containing sodium and potassium has also been proposed (Japanese Patent Laid-Open No. 6-128590), but this one has a large amount of potassium. Since it becomes water-soluble, hygroscopic, and deliquescent, it is difficult to handle.

[0005]

Under the circumstances described above, the present invention has an inorganic cation having a high cation exchange capacity and a high exchange rate, and having neither water solubility, hygroscopicity, nor deliquescent. It is made for the purpose of providing an ion exchanger.

[0006]

Means for Solving the Problems As a result of intensive studies to develop an inorganic cation exchanger having improved properties, the present inventors have found that crystalline hydrous alkali metal silicic acid having a specific composition formula. It was found that an inorganic cation exchanger composed of a salt has a high cation exchange capacity and a large exchange rate, and does not exhibit water solubility, hygroscopicity, or deliquescent, and based on this finding, the present invention was completed. It was

That is, the present invention provides a compositional formula xM ₂ O. (1-x) Na ₂ O.ySiO ₂ .zH ₂ O (I) (wherein M is an alkali metal other than sodium, x is 0.
The present invention provides an inorganic cation exchanger consisting of a crystalline hydrous alkali metal silicate represented by the formula: 01 to 1, y is 3 to 5, and z is 1 to 20).

By the way, crystalline hydrous alkali metal silicate
As the acid salt, kanemite (NaHSi₂O_Five・ 3H
₂O), macatite (Na₂Si_FourO₉・ 5H₂O), eye
Raaite (Na₂Si₈O₁₇・ 10H₂O), Magadi
Ait (Na₂Si₁₄O₂₉・ 10H ₂O), Kenyaite
(Na₂Si₂₀O₄₁・ 10H₂O) etc. are generally known
There is. All of these are layer structures consisting of silicates only
Alkali metals that are usually considered to be interchangeable between and
Contains ions.

As the inorganic cation exchanger of the present invention, the crystalline hydrous alkali metal silicate represented by the above general formula (I) is used, but those having a structure similar to the above-mentioned macatite and macatite are particularly preferable. Is. Although powder X-ray diffraction is usually used to identify these crystal structures, the diffraction pattern also changes with changes in the type and composition of metal ions contained in the layers. It is not easy to determine which one. The crystallinity referred to in the present invention means that a diffraction peak is observed in X-ray diffraction.

[0010] Macatite is a product of Kenya ["Am. Mine
ral. , Vol. 55, p. 358 (1970)]
And Russia ["Dokl Akad Nauk SSS
R ”, 255, 971 (1980)], it can be used as the inorganic cation exchanger of the present invention by modifying the natural product. However, in order to use this macatite for the purpose of the inorganic cation exchanger, it is preferable that the amount of impurities is small because of problems such as performance and coloring, but natural products are unsuitable because of the large amount of impurities.

High-purity macatite can be obtained by synthesizing it. However, examples of actually synthesizing macatite have hitherto been synthesized by a hydrothermal reaction of SiO ₂ —Na ₂ O—H ₂ O system [ "Z. Kristallogr."
Vol. 197, page 1 (1991)] and synthesized by adding diethanolamine [“Z. Krist”
allgr. 159, pp. 203 (198
Only 2 years)], and the synthesis conditions are unclear in the latter report. The composition of both natural and synthetic macatites is sodium silicate,
Until now, there has been no known example in which a part or all of the interlayer sodium ions is replaced with potassium.

The crystalline hydrous alkali metal silicate used as the inorganic cation exchanger of the present invention is represented by the composition formula xM ₂ O. (1-x) Na ₂ O.ySiO ₂ .zH ₂ O (I). It has a structure that is In this composition formula, M is an alkali metal other than sodium, but potassium is preferable because of its high effect of improving the cation exchange rate. x is a number in the range of 0.01 to 1, and 0.0
If it is less than 1, the cation exchange rate becomes slow. y is a number in the range of 3-5. When the range of y deviates from the above range, the crystalline hydrated alkali metal silicate having a layered structure becomes unstable, or a part of the alkali metal ions is exchanged with hydrogen ions, and the metal ions to be trapped. Exchangeability with From the viewpoint of stability and cation exchangeability, the preferable y is in the range of 3.5 to 4.5. On the other hand, z is a number in the range of 1 to 20, and therefore this crystalline hydrous alkali metal silicate always contains water in the crystal molecule. The distinction between water contained in a crystal molecule and water adsorbed on the surface of a crystal particle is that the water adsorbed on the particle surface is desorbed at a low temperature, but the water contained in the crystal molecule is more Since desorption is carried out at a high temperature, it is possible to quantitatively utilize this property. The amount of water contained in the crystal molecule, that is, z, is preferably in the range of 3 to 7 from the viewpoint of properties. The crystalline alkali metal silicate used as the inorganic cation exchanger of the present invention is essential to contain water of crystallization as described above.
It is essentially different from the crystalline alkali metal silicate produced by firing at a temperature of 00 ° C. or higher.

Next, an example of the method for producing the crystalline hydrous alkali metal silicate used as the inorganic cation exchanger of the present invention will be described. The simplest production method is described in "Z. Kristalllog." Vol. 197, Vol.
An example is an application of the method described on page (1991). Specifically, SiO ₂ / (Na ₂ O +
M ₂ O) molar ratio 0.05 to 6, H ₂ O / (Na ₂ O + M
₂ O) molar ratio 0.5 to 10 and M ₂ O / (Na ₂ O + M
₂ O) A hydrothermal reaction is carried out using a water-containing amorphous or aqueous solution of an alkali metal silicate having a molar ratio of 0.01 to 1 (M is an alkali metal other than sodium).

There are no particular restrictions on the raw materials used in this reaction, and various materials can be used. However, from the viewpoint of production costs, water glass, alkali metal hydroxides, and alkali metal hydroxides, which are generally readily available, are used. A combination of an aqueous carbonate solution and powdered silica is suitable. If necessary, the raw material is sufficiently homogeneously mixed with water so as to have the above composition to prepare a reaction mixture, which is then usually heated to 80 to 2 in a closed container.
Crystallization is performed at a temperature of 50 ° C., preferably 90 to 200 ° C.

In this production method, although it usually takes several hundred hours for crystallization to obtain a desired crystalline hydrous alkali metal silicate, it is possible to add an organic salt or an inorganic salt to the above reaction system. The crystallization time can be greatly shortened. As the organic salt and the inorganic salt, various ones can be used, but particularly alkali metals such as citric acid, tartaric acid, acetic acid, sulfuric acid, hydrochloric acid, hydrogen bromide, hydrogen iodide, thiocyanic acid, nitric acid, and chloric acid. Salt is preferable in terms of effect.
These organic salts and inorganic salts may be used alone or in combination of two or more. These organic salts and inorganic salts are preferably added in a proportion of 0.1 to 300% by weight based on the solid content of the water-containing amorphous substance of the alkali metal silicate or the aqueous solution. This addition amount is 0.
If it is less than 1% by weight, the effect of adding a salt is not sufficiently exerted, and if it exceeds 300% by weight, the effect is not improved for the amount, and it is substantially meaningless. From the point of effect,
The preferable addition amount of salt is 0.1 to 10 relative to the solid content.
It is in the range of 0% by weight.

The method of adding the organic salt or the inorganic salt is not particularly limited, and may be added as a powder, or in the form of an aqueous solution in order to enhance the homogeneity of the reaction system. It may be added at room temperature or under heating. It is necessary to stir at the time of addition. When adding salt under heating, it is advantageous to add an effective device for condensing evaporated water vapor and returning it to the mixture, if necessary, so that abnormal thickening and solidification of the mixture do not occur. Is. When salt is added in a closed system, a self-generated pressure is generated in the container, so it is desirable to use a pump that can deliver liquid even under such conditions.

The water content of the water-containing amorphous or aqueous solution of the alkali metal silicate thus prepared and the organic salt or the inorganic salt is adjusted as necessary. This adjustment of water content is performed by adjusting H ₂ O / (Na ₂ O + M in the reaction mixture.
₂ O) (Na and M are not derived from the above organic salts or inorganic salts, but are contained in a water-containing amorphous or aqueous solution of an alkali metal silicate) and have a molar ratio of 0.5 to 10 It is better to do so. This water content adjustment may be performed by any method and conditions, for example, simply heating, or a method utilizing spray drying or reduced pressure drying may be used. Also, by heating during this moisture adjustment,
Crystallization to the target substance can occur at the same time. In this case, it is advantageous to adjust the water content at a temperature of 250 ° C. or lower. If it exceeds 250 ° C, it is difficult to obtain a desired crystalline hydrous alkali metal layered silicate.

The reaction mixture thus prepared is
By heat treatment, the desired crystalline hydrous alkali metal silicate can be obtained. This heat treatment is from 80 to 250 ° C
It is desirable to carry out at a temperature in the range. If the heat treatment temperature is lower than 80 ° C, the treatment takes a long time and is not practical, and if it exceeds 250 ° C, a desired silicate is difficult to be produced. In order to efficiently obtain the desired silicate in a short treatment time, the heat treatment temperature is preferably in the range of 90 to 200 ° C. This heat treatment may be maintained at a certain constant temperature, or the temperature may be gradually raised or lowered in some cases. Further, the material that has been heated during the above-mentioned water content adjustment can be directly transferred to this heat treatment. In this case, the water content adjusting step and the heat treatment step are inseparable, but the amount of water finally remaining in the mixture is H ₂ O / (Na ₂ O + M ₂ O) (Na and M are derived from organic salts or inorganic salts). It is desirable that the molar ratio of the alkali metal silicate contained in the water-containing amorphous substance or the aqueous solution) is in the range of 0.5 to 10. Also,
This heat treatment can also be carried out with the reaction mixture under the flow of steam.

The time required for this heat treatment is determined depending on the degree of progress of crystallization, but it can be completed within 100 hours at the longest, usually within several tens of hours. Further, in order to promote crystallization, it is also effective to add a seed crystal of the objective crystalline hydrous alkali metal silicate to the above reaction mixture.

The desired crystalline hydrous alkali metal silicate can be obtained by washing the reaction mixture thus heat-treated in this manner with water, solid-liquid separation and drying treatment. The solid-liquid separation method is not particularly limited, and any method may be used. Further, if the drying treatment is carried out at an excessively high temperature, the crystal structure will change, and it will be difficult to obtain the desired crystalline hydrous alkali metal silicate.
It is preferable to carry out at the following temperature.

When the cation exchange capacity of the natural crystalline hydrous alkali metal silicate produced by such a method or the natural hydrate is also low, it can be modified by the following method. The most effective modification method is to treat the crystalline hydrous alkali metal silicate with an acidic substance to once transform it into a crystalline silicate or crystalline silicic acid, and then to dissolve the alkali metal salt or hydroxide. It is a method of treating with a thing. At this time, the treatment with an acidic substance is advantageously performed using an aqueous solution containing an acidic substance and having a pH of 6 or less, preferably 4 or less. As the acidic substance, for example, a mineral acid such as hydrochloric acid, sulfuric acid or nitric acid is suitable from the viewpoints that the amount used is small and the price is low. These acidic substances may be used alone or in combination of two or more.

By the treatment with such an acidic substance,
The amount of the alkali metal contained in the crystalline hydrated alkali metal silicate is preferably 50% or less before the treatment, and in particular, all of the alkali metals are replaced with hydrogen atoms, that is, the crystalline hydrate. More preferably, it is derived from silicic acid. Furthermore, in the treatment with this acidic substance, it is important that the layer structure of the crystalline hydrous alkali metal silicate is not destroyed. It should be noted that the phrase "the layer structure is not destroyed" does not mean that the layer structure is exactly the same as that of the original crystalline alkali metal silicate, and that at least a part of the crystalline alkali metal silicate is treated after the treatment with the acidic substance. It suffices to have a layered structure with. The treatment with this acidic substance is
It is preferably carried out by dispersing the crystalline alkali metal silicate in an aqueous solution in which an acidic substance is dissolved or added, and this condition is selected within a range in which the degree of ion exchange by hydrogen and the retention of the layer structure are achieved. Thus, the crystalline silicate or crystalline silicic acid obtained by treating with an acidic substance, if washed after treatment, used the following alkali metal salt or hydroxide regardless of the presence or absence of drying. It can be used for processing.

Next, the treatment with the alkali metal salt or hydroxide is carried out at a pH containing the alkali metal salt or hydroxide.
It is advantageous to carry out by using an aqueous solution of 7.5 or more, preferably 9 or more, and mixing this with a crystalline silicate or crystalline silicic acid obtained by treating with the above-mentioned acidic substance. The alkali metal is selected in consideration of the composition of the modified crystalline hydrous alkali metal silicate, and sodium or potassium is preferable. As the salt, for example, water-soluble chloride, sulfate, nitrate, carbonate and the like are suitable. These alkali metal salts and hydroxides may be used alone or in combination of two or more. In this treatment, the pH of the aqueous solution is 7.5.
If the amount is less than the above, the hydrogen ions in the crystalline silicate or crystalline silicic acid are not sufficiently exchanged with the alkali metal, and even if the exchange is sufficiently performed, it takes time, which is not preferable. The processing conditions are chosen such that the exchange of hydrogen ions for alkali metal is achieved to the desired extent and the layered structure of the modified crystalline hydrous alkali metal silicate is at least partially retained. The concentration of the aqueous solution of the alkali metal salt or hydroxide is not particularly limited, but the amount is preferably equivalent or more, particularly preferably 2 equivalents or more with respect to the crystalline silicate or crystalline silicic acid. If this amount is less than the equivalent amount, the hydrogen ions in the crystalline silicate or crystalline silicic acid are not sufficiently exchanged with the alkali metal.

When a crystalline hydrous alkali metal salt containing two or more kinds of alkali metals between layers is desired as the inorganic cation exchanger of the present invention, a salt or hydroxide of the two or more kinds of alkali metals is used. The crystalline silicate or the crystalline silicic acid obtained by the treatment of the acidic substance is used. That is, if such a modification method is used, any metal ion may be contained in the interlayer of the unmodified crystalline hydrous alkali metal silicate.

At this time, the amount of salt or hydroxide used in the treatment must be increased or decreased depending on the ease of ion exchange between hydrogen ions and the alkali metal ions used.
For example, the desired crystalline hydrous alkali metal silicate (N
a _n K _m ) ₂ Si ₄ O ₉ (macatite, n + m = 1, H ₂ O omitted), the crystalline silicic acid before treatment with the salt of Na and K or hydroxide is H ₂ Si ₄ O ₁₇ (acid-type macatite, H
₂ O is omitted), and in this case, Na ions are easier to exchange with hydrogen ions than K ions. Therefore, when the acid-type macatite is treated with an aqueous solution in which salts or hydroxides of Na and K (probably NaA and KA ') are dissolved, the quantitative ratio of NaA and KA' is set to the desired crystalline hydrous alkali metal silicate. It is necessary to increase K more than the composition ratio K / Na = m / n in the acid salt, that is, to increase the amount of those that are difficult to exchange. The ease of cation exchange depends on the type of crystalline silicic acid (salt).

The crystalline hydrous alkali metal silicate used in the inorganic cation exchanger of the present invention can be obtained by washing the crystalline hydrous alkali metal silicate treated as described above and, if necessary, drying it. . The crystalline hydrous alkali metal silicate treated by this modification method has a large cation exchange capacity as compared with the unmodified one.

The inorganic cation exchanger of the present invention can be obtained by the above-mentioned production method or modification method, and the obtained crystalline hydrous alkali metal silicate has a high cation exchange capacity and exchange rate. Show.

[0028]

INDUSTRIAL APPLICABILITY The inorganic cation exchanger comprising the crystalline hydrated alkali metal silicate of the present invention has a high cation exchange capacity and a high cation exchange rate, and therefore, for example, a water treatment agent or water. It can be suitably used as a softening agent, a cleaning agent and the like.

[0029]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, each physical property was calculated | required as follows.

(1) Identification of Crystal Structure Using powder X-ray diffractometry, as to the makatites and acid-type makatites, "Z. Kristalllog." No. 19
Volume 7, page 1 (1991) was compared with the measurement results.

(2) Composition analysis The surface adsorbed water was obtained from the weight loss after drying at 105 ° C for 72 hours, and the crystal water was obtained by subtracting the surface adsorbed water from the ignition loss at 800 ° C for 1 hour. . Fluorescent X-ray method was used for Si and alkali metal.

(3) Cation exchange capacity It was evaluated by the Ca exchange capacity. Sample 0.5g (solid content)
Is ultrasonically dispersed in 200 ml of ion-exchanged water, and separately, 25 ml of a calcium chloride aqueous solution of 6000 ppm in terms of CaO and 300 ml of an aqueous solution containing 3 ml of ammoniacal ammonium chloride pH 10 buffer are prepared and added to the sample dispersion liquid at 25 ° C. And ion-exchanged for 10 minutes. Then, the mixture was filtered, and the calcium ion concentration of the filtrate was quantified using EDTA and calculated from the following equation. Cation exchange capacity (CaCO ₃ mg / g) = [[Ca amount of test (mol) -Ca amount in filtrate (mol)] / sample amount (solid content: g)] × 10 ⁵

(4) Cation exchange rate The cation exchange capacity was evaluated in a short time. That is, in the method for measuring the cation exchange capacity, the sample dispersion liquid and the aqueous solution containing calcium ions were mixed and filtered after 1 minute. Hereinafter, the same operation was performed. However, the unit is CaC
o ₃ mg / g · min.

Example 1 The SiO ₂ / Na ₂ O molar ratio was 3.07 and the solid content was 37.6.
The water content of a commercially available aqueous solution of sodium silicate (No. 3 water glass) at wt% was adjusted at 120 ° C. so that the molar ratio of H ₂ O / Na ₂ O (Na is derived from the sodium silicate aqueous solution) was 7. Place this mixture in a stainless steel closed container 1
Crystallization was carried out at a temperature of 20 ° C. for 30 days, after which it was discharged from the container, washed with water to separate solid and liquid, and dried at 50 ° C. The resulting powder had a composition of Na ₂ Si _4.1 O _9.2 .
It was confirmed that the substance was macatite with the result of powder X-ray diffraction in 9H ₂ O, but the cation exchange capacity was 55CaC.
It was O ₃ mg / g.

Next, 20 parts by weight (as solid content) of this unmodified macatite was dispersed in 1000 parts by weight of 1N hydrochloric acid. After continuing stirring for 1 hour, filtration and washing with ion-exchanged water were performed. When the composition of the obtained powder was analyzed, it was Na ₂ O / 4SiO ₂ = 0.01 and the crystal structure was acid-type macatite.

Further, 15 parts by weight of this acid-type macatite was added to a 0.5N aqueous solution of NaOH and KOH [Na: K = 1: 1].
1 (molar ratio)] and stirred for 1 hour, followed by filtration, washing with ion-exchanged water, solid-liquid separation, and then drying at 60 ° C. The obtained powder shows crystallinity similar to that of macatite and its composition is 0.1K.
Was _{2 O · 0.9Na 2 O · 4.1SiO} 2 · 5.5H 2 O. Tables 1 and 2 show the cation exchange capacity, cation exchange rate, water of crystallization and amount of attached water.

Example 2 100 parts by weight of an aqueous sodium silicate solution (No. 3 water glass) having a SiO ₂ / Na ₂ O molar ratio of 3.1 prepared using powdered silica gel and sodium hydroxide was stirred,
Aqueous solution 7 in which 17.5 parts by weight of sodium chloride (47% by weight based on the solid content of the sodium silicate aqueous solution) is dissolved
7.5 parts by weight were added. This mixture is then placed at 120 ° C.
The water content was adjusted to adjust the total amount to 77.5 parts by weight. At this time, the molar ratio of H ₂ O / Na ₂ O (Na is derived from an aqueous solution of sodium silicate) was 7. This mixture was placed in a stainless steel closed container and crystallized at a temperature of 120 ° C. for 48 hours, then discharged from the container, washed with water, solid-liquid separated, and dried at 60 ° C. The obtained powder has a composition of Na ₂
It was observed Si _3.9 O _8.8 · 4.7H together with the results of powder X-ray diffraction at ₂ O is makatite. The cation exchange capacity was 83 CaCO ₃ mg / g.

Next, this unmodified macatite was used in Example 1.
Treated with acidic material as in. When the composition of the obtained powder was analyzed, it was Na ₂ O / 4SiO ₂ = 0.004 and the crystal structure was acid-type macatite.

Further, 15 parts by weight of this acid-type macatite was added to an aqueous solution of 0.5N NaOH and KOH [Na: K = 1: 1].
2 (molar ratio)] and stirred for 1 hour, followed by filtration, washing with ion-exchanged water, solid-liquid separation, and then drying at 60 ° C. The obtained powder shows crystallinity and has a composition of 0.19K ₂ O.0.81Na ₂ O.4.
It was 0SiO ₂ · 5.6H ₂ O. Cation exchange capacity,
Tables 1 and 2 show the cation exchange rate, the water of crystallization, the amount of attached water, and the like.

Example 3 The same as Example 2 up to the production method and the treatment with the acidic substance. Next, 0.5 part by weight of the obtained acid-type macatite is added to 0.5.
It was added to 1000 parts by weight of an aqueous solution of N NaOH and KOH [Na: K = 1: 8 (molar ratio)], stirred for 1 hour, filtered, washed with ion-exchanged water, solid-liquid separated, and then at 60 ° C. It was dried. The resulting powder showed crystallinity, _{composition, 0.4K 2 O · 0.6Na 2 O} · 4.0Si
It was O ₂ · 5.2H ₂ O. Tables 1 and 2 show the cation exchange capacity, cation exchange rate, water of crystallization and amount of attached water.

Example 4 The same as Example 2 up to the production method and treatment with an acidic substance.
It Next, 0.5 part by weight of the obtained acid-type macatite is added to 0.5.
An aqueous solution of N NaOH and LiOH [Na: Li = 2: 1
(Mole ratio)] 1000 parts by weight, and stirred for 1 hour
After that, filtration, washing with deionized water, solid-liquid separation, next
Then, it was dried at 60 ° C. The powder obtained is crystalline.
The composition is 0.27 Li₂O ・ 0.73Na₂O.3.
9 SiO ₂・ 5.9H₂It was O. Cation exchange capacity,
The cation exchange rate, water of crystallization and amount of attached water are shown in Table 1 and
It is shown in Table 2.

Comparative Example 1 13 parts by weight of sodium hydroxide was added to 100 parts by weight of an aqueous solution of sodium silicate (No. 3 water glass) having a SiO ₂ / Na ₂ O molar ratio of 3.0. This was dried at 200 ° C. and then calcined at 730 ° C. for 1 hour. The obtained powder was pulverized and the composition was analyzed. As a result, it was found that the crystal structure of Na ₂ O · 2SiO ₂ was an alkali metal disilicate in which α and β types were mixed in δ type. The cation exchange capacity and the cation exchange rate are shown in Tables 1 and 2.

Comparative Example 2 In Comparative Example 1, the amount of sodium hydroxide was adjusted to 5.5 parts by weight, and further 1.3 parts by weight of potassium hydroxide was added. Hereinafter, the same treatment as in Comparative Example 1 was performed except that the firing time was 3 hours. The obtained powder has a composition of 0.05 K ₂
O ・ 0.95Na ₂ O ・ 2.0SiO ₂ , the crystal structure is δ
It was a type alkali metal disilicate. The cation exchange capacity and the cation exchange rate are shown in Tables 1 and 2.

COMPARATIVE EXAMPLE 3 The alkali metal disilicates obtained in Comparative Examples 1 and 2 were treated by the same modification method as in Example 1, and at the stage of treatment with an aqueous solution of potassium hydroxide and sodium hydroxide. , 9
8% has dissolved.

Comparative Example 4 Silica gel and sodium hydroxide were used to produce SiO ₂ / N.
An aqueous solution of alkali metal silicic acid having a molar ratio of a ₂ O of 4.0 was prepared. After drying it at 200 ℃, 700
Firing was performed at 38 ° C. for 38 hours. This powder was confirmed by X-ray diffraction to be crystalline, but had a cation exchange capacity of 62C.
It was as small as aCO ₃ mg / g. Table 1 shows the properties of this product.
And shown in Table 2.

Comparative Example 5 The alkali metal disilicate obtained in Comparative Example 4 was used in Example 1
The same modification method as described above was used. Although 20% was dissolved during the treatment process, the properties of the remaining product are shown in Tables 1 and 2.

Comparative Example 6 In Example 2, 15 parts by weight of acid-type macatite was added to 0.1 parts by weight.
Aqueous solution of 5N NaOH and KOH [Na: K = 1: 2
(Mole ratio)] The same treatment as in Example 2 was carried out except that 1000 parts by weight was added. The obtained material was crystalline, but the composition was 0.16K ₂ O.0.84Na ₂ O.5.5S.
It was iO ₂ · 6.2H ₂ O. Table 1 and Table 2 show the cation exchange capacity, cation exchange rate, water of crystallization and amount of attached water.
Shown in

Comparative Example 7 In Example 2, 15 parts by weight of acid-type macatite was added to 0.5 parts.
Except that 1000 parts by weight of N NaOH aqueous solution was added.
Processed as in Example 2. The obtained substance has the same crystal structure as macatite, and the composition is Na ₂ O.3.9Si.
It was O ₂ · 4.9H ₂ O. Tables 1 and 2 show the cation exchange capacity, cation exchange rate, water of crystallization and amount of attached water.

[0049]

[Table 1]

[0050]

[Table 2]

Claims (2)

[Claims] 1. A composition formula: xM ₂ O. (1-x) Na ₂ O.ySiO ₂ .zH ₂ O (wherein M is an alkali metal other than sodium, x is 0.
An inorganic cation exchanger comprising a crystalline hydrated alkali metal silicate represented by the formula: 01 to 1, y is 3 to 5, and z is 1 to 20). 2. The inorganic cation exchanger according to claim 1, wherein the alkali metal other than sodium is potassium.