JP7174413B2 - Method for synthesizing saponite-type clay mineral - Google Patents

Description

The present invention relates to a method for synthesizing a saponite-type clay mineral.

Clay minerals are generally layered silicates, and because they can incorporate water, metal ions, and organic matter between the layers, they are used in a wide range of fields as functional materials such as ion exchange, catalysts, and humidity control. . Among them, saponite, which is a trioctahedral layered silicate composed of silicon, aluminum, magnesium, sodium, oxygen, and hydrogen, has excellent oil adsorption performance and is also used as an auxiliary agent for detergents. there is
In the use of clay minerals, there are cases where natural products are refined to a higher degree of purity, and there are cases where highly pure synthetic products are used. It is required to be able to synthesize with

Against this background, developments have also been made on the synthesis of saponite, and various synthesis methods have been proposed.

One method for synthesizing saponite is a method of heating and melting solid raw materials.
For example, Patent Document 1 describes that a silica raw material, an alumina raw material, a magnesium raw material, a sodium and/or lithium raw material, and a fluoride raw material are heated and melted at 790 to 930° C. in a solid state to produce a synthetic saponite. It is

As another method, there is a method of hydrothermal synthesis using a raw material aqueous solution.
For example, in Patent Document 2, excess alkali, especially ammonia hydrated gel is precipitated from a mixed solution of water glass, magnesium salt, and aluminum salt, and after washing and removing by-product solutes, monovalent or divalent positive It is described that ions and fluorine ions are added and synthesized by a hydrothermal reaction at about 300°C.

Further, in Patent Document 3, water glass, magnesium chloride, and aluminum chloride are used as raw materials, and after washing with ammonia, hydrothermal treatment is performed at 300° C. to synthesize a clay mineral similar to saponite. The patent document states that the compound can be synthesized without adding fluorine ions.

Furthermore, in Patent Document 4, a swelling synthetic saponite-type clay mineral is produced by hydrothermally treating a mixture of basic magnesium carbonate, sodium silicate, and sodium aluminate. In this synthesis method, by using basic magnesium carbonate as a magnesium component, it does not contain fluorine ions, which are essential components in the conventional saponite synthesis, and hydrothermal conditions at low temperatures (100 to 300° C., 0.00 to 100° C.). 5 to 20 hours) made it possible to synthesize saponite.

JP-A-1-160817 Japanese Patent Publication No. 63-6486 Japanese Patent Publication No. 6-62290 JP-A-2-48411

As described above, saponite has been synthesized by various methods.
However, in the method described in Patent Document 1, since the melting reaction is performed in a solid phase state, it is performed under a high temperature condition of 700° C. or higher, which is necessary for heating and melting, and a fluoride raw material is required. There was a problem of
In addition, the methods described in Patent Documents 2 and 3 are synthesized by hydrothermal synthesis using inexpensive acidic magnesium such as magnesium sulfate and magnesium chloride as magnesium raw materials, and the method described in Patent Document 1 It can be synthesized at a relatively low temperature. However, the method described in Patent Literature 2 produces a large amount of by-product salts due to the multistage reaction operation and the use of a large amount of ammonia or alkali. In addition, in both the methods described in Patent Documents 2 and 3, water glass (a concentrated aqueous solution of sodium silicate (Na ₂ SiO ₃ )) is used as a raw material, and in water glass, SiO ₄ tetrahedrons are polymerized in a complicated manner. Therefore, synthesis was performed at a high temperature of about 300°C.
On the other hand, in the method described in Patent Document 4, sodium silicate is used as a raw material, and hydrothermal conditions at low temperatures (100 to 300° C.) are possible. However, in this method, if magnesium carbonate, magnesium hydroxide, or a mixture thereof is used as the basic magnesium carbonate used as the magnesium component, saponite cannot be obtained in a high yield and high purity, so hydromagnesite is expensive. It is particularly desirable to use

The present invention has been made in view of the above circumstances, and provides a method for synthesizing saponite, which can be synthesized at a lower temperature and at a lower cost than before, without using ammonia or fluorine. It is intended for

The inventors of the present invention have made studies to achieve the above object, and have found that the problem can be solved by using sodium orthosilicate (Na ₄ SiO ₄ ) as a raw material for silicic acid. Based on this knowledge, as a result of further investigation, acidic magnesium salt, sodium orthosilicate, and aluminum salt were used as raw materials, and after mixing these aqueous solutions, pH was adjusted, and after desalting, 130 We found that it can be synthesized by hydrothermal synthesis at ~200°C. The saponite obtained by synthesis is hereinafter referred to as "saponite-type clay mineral".

The present invention has been completed based on these findings, and is as follows.
[1] Using acidic magnesium salt, sodium orthosilicate, and aluminum salt as raw materials, mixing these aqueous solutions, adjusting the pH to 9 to 12, desalting, and heating at 130 to 200 ° C. By doing so, in the powder X-ray diffraction pattern using Cu as the X-ray source, there are peaks near 2θ = 5.2 to 6.5 ° and 2θ = 60.5 °, and 2θ = 5.2 to 6 A method for synthesizing a saponite-type clay mineral, characterized in that the peak at 0.5° is shifted to 2θ=4.3-5.1 by ethylene glycol treatment.
[2] An aqueous solution of an acidic magnesium salt, an aqueous solution of sodium orthosilicate, and an aqueous solution of an aluminum salt were mixed in a molar ratio of Mg:Si:Al of 5.0-6.0:6.8-7.5:0. The method according to [1], characterized in that the mixing ratio is from 5 to 1.2.

According to the present invention, by using acidic magnesium salt, sodium orthosilicate, and aluminum salt as raw materials, a saponite-type clay mineral can be easily and inexpensively produced at a low temperature of 130 to 200° C. without using ammonia or fluorine. We can provide a synthetic method.

1 is a powder X-ray diffraction pattern of the product obtained in Example 1. FIG. Powder X-ray diffraction pattern of the product obtained in Example 2. Powder X-ray diffraction pattern of the product obtained in Example 3. Powder X-ray diffraction pattern of the product obtained in Comparative Example.

Next, the present invention will be described in more detail.
The saponite-type clay mineral of the present invention has silicon (Si), aluminum (Al), magnesium (Mg), sodium (Na), oxygen (O) and hydrogen (H) as main constituent elements, and is composed of Si tetrahedrons. It is a trioctahedral type layered silicate clay mineral formed from a combination of tetrahedral layers and octahedral layers composed of Al and Mg.

In the present invention, acidic magnesium salt, sodium orthosilicate, and aluminum salt are used as raw materials for synthesizing this layered silicate clay mineral. It is synthesized by forming an octahedral layer made of Mg.
This layered silicate clay mineral is obtained by mixing an acidic magnesium salt aqueous solution, a sodium orthosilicate aqueous solution, and an aluminum salt aqueous solution with a Mg:Si:Al molar ratio of 5.0 to 6.0:6.8. ~7.5: 0.5 ~ 1.2 by mixing, adjusting the pH to 9 ~ 12 with acid, then desalting and heating at 130 ~ 200 ° C. artificially It is possible to obtain

Specific examples of acidic magnesium salts include magnesium chloride, magnesium nitrate, magnesium sulfate, and the like, which are suitable.
Also sodium orthosilicate is used as a silicon source.
Furthermore, aluminum salts may be aluminum ions, and specific examples thereof include aluminum compounds such as aluminum chloride, aluminum nitrate, aluminum sulfate, and sodium aluminate. These silicon sources and aluminum sources are not limited to the above-mentioned compounds, and can be used similarly as long as they have the same effect.

These raw materials are dissolved in an appropriate aqueous solution to prepare a solution with a predetermined concentration. In order to synthesize the saponite-type clay mineral for this purpose, Mg, Si, and Al are mixed so that the molar ratio is 5.0 to 6.0: 6.8 to 7.5: 0.5 to 1.2. It is necessary to. The concentration of the acidic magnesium salt aqueous solution in the solution is 0.1 to 1 mol/L, the concentration of the sodium orthosilicate aqueous solution is 0.1 to 1 mol/L, and the concentration of the aluminum salt aqueous solution is 0.01 to 0.1 mol/L. L, but suitable concentrations include 0.1 to 0.6 mol/L aqueous solution of acidic magnesium salt, 0.1 to 0.6 mol/L aqueous solution of sodium orthosilicate, and 0.01 to 0 It is preferable to mix an aqueous solution of aluminum salt at 0.06 mol/L. Based on these ratios and concentrations, an aqueous solution of sodium orthosilicate is mixed with a solution of acidic magnesium salt and aluminum salt, and an acid or alkali is added to adjust the pH to 9 to 12 to obtain a precursor. After forming, the coexisting ions in the solution are removed by centrifugation, filtration, membrane separation, or the like. The solid content recovered after the desalting treatment is dispersed in pure water, the solid content is recovered again by desalting treatment, and the solid content dispersed in the pure water is the saponite-type clay mineral. is a suspension containing a precursor material.

A saponite-type clay mineral can be obtained by heating a suspension containing this precursor substance at 130 to 200°C.

EXAMPLES Next, the present invention will be specifically described based on Examples and Comparative Examples, but the present invention is not limited by the following Examples.
(Example 1)
As Mg and Al sources, magnesium chloride and aluminum chloride were dissolved in pure water, and 175 mL of an aqueous solution with a Mg concentration of 0.34 mol/L and an Al concentration of 0.047 mol/L was used. As a Si source, 175 mL of an aqueous solution of sodium orthosilicate dissolved in pure water and having a Si concentration of 0.41 mol/L was used. An aqueous solution in which magnesium chloride and aluminum chloride were dissolved was added to the sodium orthosilicate aqueous solution, and the mixture was stirred by rotating a stirrer at a speed of 600 rpm for about 2 hours until the solution became homogeneous. 48 mL of 1 mol/L HCl was added until the pH was 10.1 for about half of the stirred solution and stirred overnight.
After stirring overnight, the solid liquid is separated by centrifugation. Pure water is added to the collected solids and stirred for 10 minutes. The solid-liquid was again separated by centrifugation, pure water was added to the recovered solid content to make the total volume of the solution 200 mL, and the mixture was further stirred overnight.
After stirring, about 18 mL of the suspension was placed in a Teflon (registered trademark) cup and heated at 200° C. for 7 days. After heating at a speed of 11,000 rpm, solid-liquid separation was performed by centrifugation. A part of the collected solid content was pasted on a slide glass, and the remaining solid content was dried at 60° C. for one day or longer.

The composition of the product obtained in Example 1 was analyzed by fluorescent X-rays. The chemical composition of the product obtained was as follows.
_Mg5.7 ( _Si7.5 , _Al0.5 ) _O20 (OH) ₄

The product obtained in Example 1 was subjected to powder X-ray diffraction measurement.
FIG. 1 shows the powder X-ray diffraction pattern of the product obtained. As seen in FIG. 1(a), a peak was observed at 2θ=6.0°, which was shifted to 2θ=5.0° by ethylene glycol treatment. Moreover, as seen in FIG. 1(b), a peak was observed at 2θ=60.7°.
From the chemical composition and powder X-ray diffraction results, it was confirmed that the substance of Example 1 was a saponite-type clay mineral.

(Example 2)
As Mg and Al sources, magnesium chloride and aluminum chloride were dissolved in pure water, and 175 mL of an aqueous solution with a Mg concentration of 0.34 mol/L and an Al concentration of 0.047 mol/L was used. As a Si source, 175 mL of an aqueous solution of sodium orthosilicate dissolved in pure water and having a Si concentration of 0.41 mol/L was used. An aqueous solution in which magnesium chloride and aluminum chloride were dissolved was added to the sodium orthosilicate aqueous solution, and the mixture was stirred by rotating a stirrer at a speed of 600 rpm for about 2 hours until the solution became homogeneous. 48 mL of 1 mol/L HCl was added until the pH was 10.1 for about half of the stirred solution and stirred overnight.
After stirring overnight, the solid liquid is separated by centrifugation. Pure water is added to the collected solids and stirred for 10 minutes. The solid-liquid was again separated by centrifugation, pure water was added to the recovered solid content to make the total volume of the solution 200 mL, and the mixture was further stirred overnight.
After stirring, about 18 mL of the suspension was placed in a Teflon cup and heated at 200° C. for 2 days. After heating at a speed of 11,000 rpm, solid-liquid separation was performed by centrifugation. A part of the collected solid content was pasted on a slide glass, and the remaining solid content was dried at 60° C. for one day or more.

The composition of the product obtained in Example 2 was analyzed by fluorescent X-rays. The chemical composition of the product obtained was as follows.
_Mg5.7 ( _Si7.5 , _Al0.5 ) _O20 (OH) ₄

The product obtained in Example 2 was subjected to powder X-ray diffraction measurement.
FIG. 2 shows the powder X-ray diffraction pattern of the product obtained. As seen in FIG. 2(a), a peak was observed at 2θ=6.0°, which was shifted to 2θ=5.0° by ethylene glycol treatment. Moreover, as seen in FIG. 2(b), a peak was observed at 2θ=60.7°.
From the chemical composition and powder X-ray diffraction results, it was confirmed that the material of Example 2 was a saponite-type clay mineral.

(Example 3)
As Mg and Al sources, magnesium chloride and aluminum chloride were dissolved in pure water, and 175 mL of an aqueous solution with a Mg concentration of 0.34 mol/L and an Al concentration of 0.047 mol/L was used. As a Si source, 175 mL of an aqueous solution of sodium orthosilicate dissolved in pure water and having a Si concentration of 0.41 mol/L was used. An aqueous solution in which magnesium chloride and aluminum chloride were dissolved was added to the sodium orthosilicate aqueous solution, and the mixture was stirred by rotating a stirrer at a speed of 600 rpm for about 2 hours until the solution became homogeneous. To about one-sixth of the stirred solution, 13.5 mL of 1 mol/L HCl was added until the stirred pH was 12.0, and stirred overnight.
After stirring overnight, the solid liquid is separated by centrifugation. Pure water is added to the collected solids and stirred for 10 minutes. The solid-liquid was again separated by centrifugation, pure water was added to the recovered solid content to make the total volume of the solution 200 mL, and the mixture was further stirred overnight.
After stirring, about 18 mL of the suspension was placed in a Teflon cup and heated at 130° C. for 7 days. After heating at a speed of 11,000 rpm, solid-liquid separation was performed by centrifugation. A part of the collected solid content was pasted on a slide glass, and the remaining solid content was dried at 60° C. for one day or longer.

The composition of the product obtained in Example 3 was analyzed by fluorescent X-rays. The chemical composition of the product obtained was as follows.
_Mg5.7 ( _Si7.5 , _Al0.5 ) _O20 (OH) ₄

The product obtained in Example 3 was subjected to powder X-ray diffraction measurement.
FIG. 3 shows the powder X-ray diffraction pattern of the product obtained. As seen in FIGS. 3(a) and (b), a peak was observed at 2θ=5.3°, and this peak was shifted to 2θ=4.5° by ethylene glycol treatment. Moreover, as seen in FIG. 3(c), a peak was observed at 2θ=60.5°.
From the chemical composition and powder X-ray diffraction results, it was confirmed that the material of Example 3 was a saponite-type clay mineral.

(Comparative example)
As Mg and Al sources, magnesium chloride and aluminum chloride were dissolved in pure water, and 175 mL of an aqueous solution with a Mg concentration of 0.34 mol/L and an Al concentration of 0.047 mol/L was used. As a Si source, 175 mL of an aqueous solution of sodium orthosilicate dissolved in pure water and having a Si concentration of 0.41 mol/L was used. An aqueous solution in which magnesium chloride and aluminum chloride were dissolved was added to the sodium orthosilicate aqueous solution, and the mixture was stirred by rotating a stirrer at a speed of 600 rpm for about 2 hours until the solution became homogeneous. To about one sixth of the stirred solution, add 16.5 mL of 1 mol/L HCl and 0.6 mL of 1 mol/L NaOH to a pH of 8.9 after stirring overnight. Stirred.
After stirring overnight, the solid liquid is separated by centrifugation. Pure water is added to the collected solids and stirred for 10 minutes. The solid-liquid was again separated by centrifugation, and pure water was added to the recovered solid to make the total volume of the solution 80 mL, and the mixture was further stirred overnight.
After stirring, about 18 mL of the suspension was placed in a Teflon cup and heated at 200° C. for 7 days. After heating at a speed of 11,000 rpm, solid-liquid separation was performed by centrifugation. A part of the collected solid content was pasted on a slide glass, and the remaining solid content was dried at 60° C. for one day or more.

A powder X-ray diffraction measurement was performed on the product obtained in the comparative example. FIG. 4 shows the powder X-ray diffraction pattern of the product obtained.
As shown in FIG. 4, no peaks were observed in the powder X-ray diffraction pattern, confirming that no saponite-type clay mineral was synthesized.

(Example 4)
Next, the following experiment was conducted in order to investigate the pH range during heating in which the saponite-type clay mineral is formed.
As Mg and Al sources, magnesium chloride and aluminum chloride were dissolved in pure water, and 175 mL of an aqueous solution with a Mg concentration of 0.34 mol/L and an Al concentration of 0.047 mol/L was used. As a Si source, 175 mL of an aqueous solution of sodium orthosilicate dissolved in pure water and having a Si concentration of 0.41 mol/L was used. An aqueous solution in which magnesium chloride and aluminum chloride were dissolved was added to the sodium orthosilicate aqueous solution, and the mixture was stirred by rotating a stirrer at a speed of 600 rpm for about 2 hours until the solution became homogeneous. The stirred solution was divided into several beakers, and different amounts of 1 mol/L HCl and 1 mol/L NaOH were added to each, and the pH was adjusted to 2.8, 8.3, 8.9, 9.3, 9. .8, 10.1, 11.4, 12.0, 13.1 and stirred overnight.
After stirring overnight, the solid liquid is separated by centrifugation. Pure water is added to the collected solids and stirred for 10 minutes. The solid-liquid was again separated by centrifugation, and pure water was added to the recovered solid to make the total volume of the solution 80 to 230 mL, and the mixture was further stirred overnight.
After stirring, about 18 mL of the suspension was placed in a Teflon cup and heated at 200° C. for 7 days. After heating, solid-liquid separation was performed by centrifugation at a speed of 11,000 rpm, a portion of the collected solid content was pasted on a slide glass, and the remaining solid content was dried at 60° C. for 1 day or more.

Powder X-ray diffraction measurement was performed on each of the obtained products. As a result, saponite-type clay minerals were formed at pH values of 9.3, 9.8, 10.1, 11.4, and 12.0, but at pH values of 2.8, 8.3, 8.9, No saponite-type clay mineral was formed at 13.1.
From this result, it was shown that the pH range at which the saponite-type clay mineral is formed when the solutions are mixed is 9-12.

(Example 5)
Furthermore, the following experiments were conducted to investigate the temperature range during heating in which saponite-type clay minerals are formed.
As Mg and Al sources, magnesium chloride and aluminum chloride were dissolved in pure water, and 175 mL of an aqueous solution with a Mg concentration of 0.34 mol/L and an Al concentration of 0.047 mol/L was used. As a Si source, 175 mL of an aqueous solution of sodium orthosilicate dissolved in pure water and having a Si concentration of 0.41 mol/L was used. An aqueous solution in which magnesium chloride and aluminum chloride were dissolved was added to the sodium orthosilicate aqueous solution, and the mixture was stirred by rotating a stirrer at a speed of 600 rpm for about 2 hours until the solution became homogeneous. The stirred solution was divided into several beakers and 1 mol/L HCl was added to each to bring the pH to 10-12 and stirred overnight.
After stirring overnight, the solid liquid is separated by centrifugation. Pure water is added to the collected solids and stirred for 10 minutes. The solid-liquid was again separated by centrifugation, and pure water was added to the recovered solid to make the total volume of the solution 80 to 230 mL, and the mixture was further stirred overnight.
After stirring, about 18 mL of the suspension was placed in a Teflon cup and heated at 130-200° C. for 7 days. After heating, solid-liquid separation was performed by centrifugation at a speed of 11,000 rpm, a portion of the collected solid content was pasted on a slide glass, and the remaining solid content was dried at 60° C. for 1 day or longer.

Powder X-ray diffraction measurement was performed on each of the obtained products. As a result, saponite-type clay minerals were formed at temperatures of 130, 140, 150, 180 and 200°C, but no saponite-type clay minerals were formed at temperatures of 100 and 120°C.
This result indicates that the temperature range at which the saponite-type clay mineral is formed when the suspension is heated is 130 to 200°C.

Claims (2)

Acidic magnesium salt, sodium orthosilicate and aluminum salt are used as raw materials, and after mixing these aqueous solutions, the pH is adjusted to 9 to 12, desalted, and then heated at 130 to 200 ° C. In the powder X-ray diffraction pattern using Cu as the X-ray source, there are peaks near 2θ = 5.2 to 6.5° and 2θ = 60.5°, and 2θ = 5.2 to 6.5°. A method for synthesizing a saponite-type clay mineral, characterized in that the peak is shifted to 2θ=4.3-5.1 by ethylene glycol treatment. An aqueous solution of an acidic magnesium salt, an aqueous solution of sodium orthosilicate, and an aqueous solution of an aluminum salt were mixed in a molar ratio of Mg:Si:Al of 5.0-6.0:6.8-7.5:0.5-1. 2. A method according to claim 1, characterized by mixing to .2.

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