KR102655710B1 - Synthesis method of layered silicate and layered silicate synthesized by the same - Google Patents

Abstract

The layered silicate synthesis method according to the present invention uses spherical silica particles with an average particle diameter of 20 ㎛ or more as a silica source to synthesize layered silicate, thereby forming a layered silicate in the form of a core-shell where the core is porous and the outer shell has a layered structure. Silicates can be synthesized, and the inside is porous and the outside has a closed structure, so it can be used in various applications such as micro reactors and drug delivery materials. In addition, the layered silicate synthesis method according to the present invention synthesizes layered silicate using spherical silica particles with an average particle diameter of 20 ㎛ or more as a silica source, thereby improving the efficiency of the synthesis process by shortening the hydrothermal synthesis time.

Description

Synthesis method of layered silicate and layered silicate synthesized therefrom {Synthesis method of layered silicate and layered silicate synthesized by the same}

The present invention relates to a method for synthesizing a layered silicate comprising a porous core and a layered shell, and to a layered silicate synthesized therefrom.

Layered silicates, such as magadite or kenyanite, which are representative crystalline layered compounds, are compounds that exhibit a crystalline structure made of pure silicon dioxide (SiO ₂ ), unlike most natural clay minerals made of aluminosilicate, and were discovered in 1960. Since it was first discovered in the middle of 2012, silicon dioxide has been artificially synthesized and used through a hydrothermal reaction in an alkaline atmosphere.

Among layered silicates, margardite and kenyanite, which are easy to disperse in each layer, are representative. Among these, margardite is formed by combining SiO ₄ tetrahedra as a basic unit in a planar shape, and these planar sheets are overlapped to form one layer. It forms layers, and these are stacked to form independent individual plate-shaped structures (plates), and these plate-shaped structures form a bundle like a rose flower. Kenyaite has the same appearance as Magadite, except that it is composed of thicker layers than Magadite due to overlapping SiO ₄ tetrahedral sheets.

Layered silicates such as magadite or kenyanite have an excellent cation exchange capacity of about 130 to 180 meq/100 g, have excellent thermal stability and chemical resistance, and have an elaborately separated plate structure, so they can be used in existing natural products. Alternatively, it has properties that are distinct from synthetic clay. In other words, most natural or synthetic clay minerals have a layered structure, but like magadite or kenyanite, the individual plate structures are very regularly and precisely separated, so rather than being able to be scattered individually, the individual layers clump together and form a lump. In most cases, it is difficult to clearly determine the presence or absence of a layered structure based on the external appearance because it represents the shape.

Recently, as the excellent physical properties of clay-polymer nanocomposite have become known, new light is being shed on these clay minerals. Among various clay minerals, layered silicates such as margardite or kenyanite are known for their unique morphology. As a result, it has been revealed that nanocomposites have various possibilities for optimally improving their physical properties.

However, despite the structural characteristics of layered silicates such as margardite or kenyanite, the development of methods for economically producing them and technologies for using the produced layered silicates is minimal.

In addition, the conventionally known method of synthesizing layered silicates is most commonly produced in a flower-like shape, but it is difficult to control the shape of the layered silicate structure, so the shape of the structure cannot be modified to suit the intended use. It had the disadvantage of having a somewhat narrow application field, and also had the problem that the hydrothermal synthesis time required to synthesize layered silicates took a long time. In relation to this, Korean Patent Publication No. 1992-7002852 describes the synthesis of a kenyanite-type layered silicate material, but even in that document, it takes a relatively long time to proceed with the hydrothermal synthesis reaction, and also requires the shape of the layered silicate structure. I can't control it.

Accordingly, in order to expand the industrial applications of layered silicates, research on synthetic methods that can control the shape of the structure and improve process efficiency is urgently needed.

KR1992-7002852A

The present invention was devised to solve the problems of the prior art, and provides a method for synthesizing a core-shell layered silicate comprising a porous core and a shell with a layered structure.

Another object of the present invention is to provide a method for synthesizing layered silicates that improves process efficiency by shortening the hydrothermal synthesis time during layered silicate synthesis.

Another object of the present invention is to provide a core-shell type layered silicate produced by the above production method and including a porous core and a shell with a layered structure.

In order to solve the above problems, the present invention includes the steps of 1) mixing a silica source, a basic material, and water to form a reactant solution; and 2) hydrothermally synthesizing the reactant solution to form a layered silicate, wherein the silica source is a spherical silica particle having an average particle diameter (D50) of 20 ㎛ or more.

Additionally, the present invention provides a porous core; and a shell having a layered structure, wherein the core and shell are made of silica.

The layered silicate synthesis method according to the present invention uses spherical silica particles with an average particle diameter of 20 ㎛ or more as a silica source to synthesize layered silicate, thereby forming a layered silicate in the form of a core-shell where the core is porous and the outer shell has a layered structure. Silicates can be synthesized.

In addition, the layered silicate of the present invention has a closed structure with a porous interior and a dense layered structure on the outer surface, so that the adsorption capacity of the layered silicate can be further improved, and the specific surface area within the layered structure including a porous core is Since it can be greatly improved, the adsorption capacity can be greatly increased.

In addition, as a porous silica core is formed within the layered shell, substances such as polymers, pharmaceuticals, and enzymes that can be inserted between layers can penetrate more easily, which significantly improves compatibility with substances such as polymers. You can. Due to these characteristics, the application range of the layered silicate of the present invention can be greatly expanded, and it can be used in a variety of applications, such as reinforcing polymer resins, fillers in cosmetics, nanocomposites, microreactors, and drug delivery materials.

In addition, the layered silicate synthesis method according to the present invention synthesizes layered silicate using spherical silica particles with an average particle diameter of 20 ㎛ or more as a silica source, thereby improving the efficiency of the synthesis process by shortening the hydrothermal synthesis time.

Figure 1 shows an SEM photograph of spherical silica particles prepared in Preparation Example 1.
Figure 2 shows an SEM photograph of spherical silica particles prepared in Preparation Example 2.
Figure 3 shows an SEM photograph of amorphous silica particles prepared in Comparative Preparation Example 1.
Figures 4 and 5 show SEM photographs of the layered silicate prepared in Example 1.
Figure 6 shows an SEM photograph of the layered silicate prepared in Example 2.
Figure 7 shows an SEM photograph of the layered silicate prepared in Example 3.
Figure 8 shows an SEM photograph of the layered silicate prepared in Example 4.
Figure 9 shows an SEM photograph of the layered silicate prepared in Example 5.
Figure 10 shows an SEM photograph of the layered silicate prepared in Comparative Example 1.
Figure 11 shows an SEM photograph of the layered silicate prepared in Comparative Example 2.
Figure 12 shows the results of XRD analysis of the layered silicate prepared in Example 1.

Hereinafter, the present invention will be described in more detail to facilitate understanding of the present invention.

Terms or words used in this specification and claims should not be construed as limited to their common or dictionary meanings, and the inventor may appropriately define the concept of terms in order to explain his or her invention in the best way. It must be interpreted with meaning and concept consistent with the technical idea of the present invention based on the principle that it is.

The method for synthesizing layered silicate according to an embodiment of the present invention includes the steps of 1) mixing a silica source, a basic material, and water to form a reactant solution; and 2) hydrothermally synthesizing the reactant solution to form layered silicate, wherein the silica source is a spherical silica particle with an average particle diameter (D50) of 20 ㎛ or more.

Here, the average particle diameter (D50) can be defined as the particle size corresponding to 50% of the cumulative number of particles in the particle size distribution curve. The average particle diameter (D50) can be measured using, for example, a laser diffraction method. The laser diffraction method is generally capable of measuring particle diameters ranging from the submicron region to several millimeters, and can obtain results with high reproducibility and high resolution.

In addition, the layered silicate of the present invention is a silicate crystal made of silicon dioxide, and may include a layered lamellar structure. In particular, the layered silicate according to an embodiment of the present invention has a layered shell and a porous core. It is a silicate containing a structure.

In addition, the layered silicate of the present invention may specifically include margardite or kenyanite, and more specifically, may include margardite or kenyanite including a porous core and a layered shell.

Specifically, the silica source according to an embodiment of the present invention may be a spherical silica particle, and the silica particles are secondary silica particles formed into a sphere by agglomerating primary silica particles on the primary particles. It may be silica particles on particles (secondary silica particles). In addition, the spherical silica particles can be obtained from a reaction product obtained by reacting a silica material with a neutralizing agent and a gelling agent, and can be obtained by selectively adding a surfactant to promote the production of spherical silica particles. You can get it.

More specifically, the spherical silica particles of the present invention may be manufactured by mixing a silica material and an organic solvent to prepare a silica precursor solution, adding a neutralizing agent and a gelling agent, and drying the reacted silica gel. Additionally, optionally, additional surfactant may be added to the silica precursor solution, and phase separation and washing processes may be further included before drying.

Here, the silica material can be used without limitation as long as it can form spherical silica particles, for example, water glass solution, tetramethyl orthosilicate (TMOS), tetraethyl orthosilicate (tetraethyl A silicon-containing alkoxide-based compound such as orthosilicate (TEOS) or methyl triethyl orthosilicate can be used, and in the present invention, more specifically, a water glass solution can be used.

The water glass in the water glass solution has a relatively low raw material cost among realistically available silica materials, so when water glass is used to produce a silica source, it can have an economic effect in terms of production cost.

In the present invention, the water glass solution may represent a diluted solution obtained by adding and mixing distilled water to water glass, and the water glass is sodium silicate (Na ₂ ), an alkali silicate salt obtained by melting silicon dioxide (SiO ₂ ) and an alkali. It may be SiO ₃ ).

In addition, according to one embodiment of the present invention, the neutralizing agent for neutralizing the silica material may include an acid material, and acids that can be used as the neutralizing agent include fluorosilicic acid (H ₂ SiF ₆ ), sulfuric acid (H ₂ SO ₄ ), Inorganic acids including hydrochloric acid (HCl), nitric acid (HNO ₃ ), phosphoric acid (H ₃ PO ₄ ) and hydrofluoric acid (HF), acetic acid (CH ₃ COOH), oxalic acid, maleic acid, malic acid There may be organic acids including malonic acid, citric acid, and propionic acid, and when considering ease of pH adjustment, ease of handling, and safety of the reactants, acetic acid is preferably included. can do.

In addition, the gelling agent according to an embodiment of the present invention can be used without limitation as long as it is a material that can gel the silica precursor into silica gel, specifically isopropanol, sodium hydroxide (NaOH), and potassium hydroxide (KOH). , calcium hydroxide (Ca(OH) ₂ ), ammonia (NH ₃ ), ammonium hydroxide (NH ₄ OH), tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide. (TPAH), tetrabutylammonium hydroxide (TBAH), methylamine, ethylamine, isopropylamine, monoisopropylamine, diethylamine, diisopropylamine, dibutylamine, trimethylamine, triethylamine, trimethylamine Isopropylamine, tributylamine, choline, monoethanolamine, diethanolamine, 2-aminoethanol, 2-(ethyl amino)ethanol, 2-(methyl amino)ethanol, N-methyl diethanolamine, dimethylaminoethanol, It may be one or more selected from the group consisting of diethylaminoethanol, nitrilotriethanol, 2-(2-aminoethoxy)ethanol, 1-amino-2-propanol, triethanolamine, monopropanolamine, dibutanolamine, and pyridine. Preferably, it may be sodium hydroxide, ammonium hydroxide, potassium hydroxide, isopropanol, or a mixture thereof.

In addition, the spherical silica particles according to an embodiment of the present invention may have an average particle diameter (D50) of 20㎛ or more, and in terms of forming a structure of the desired shape and improving process efficiency, the average particle diameter is specifically It may be 20 to 60 ㎛, and more preferably 30 to 55 ㎛.

In the present invention, silica particles on nano-level primary particles are aggregated to form spherical silica particles on secondary particles in the above particle size range, so that when a hydrothermal synthesis reaction for layered silicate synthesis is performed, the silica constituting the particles A layered structure of layered silicate is formed from the surface of the particle due to the crystallization action of the salt component of the basic substance, such as sodium component, present in the solution of the components and reactants. In addition, due to the dissolution and reprecipitation reaction of silica, the pores of the core gradually become larger, and the inner core forms a porous silica structure without a layered structure, and the particles The shell, which is the surface, can form a flower-shaped magadite or kenyanite layered structure surrounding the core.

When amorphous silica particles that are not spherical but have an irregular shape are used as a silica source, the order of reaction locations is not determined and multiple reactions occur randomly, forming a layered silicate in the form of a core-shell with a porous core. Can not. In addition, even if spherical silica particles are used, if the particle size is less than 20 ㎛, the particles are so small that most of the silica components constituting the particles are salts of basic substances in the reactant solution before a layered shell is first formed on the surface of the particles. Since the crystallization reaction is performed in direct contact with components, such as sodium components, the entire silica particle is crystallized only in a layered structure, making it difficult to form core-shell particles containing both a porous core and a layered shell, especially nano This phenomenon appears more clearly when using silica particles of similar size, such as colloidal silica particles.

According to one embodiment of the present invention, the reactant solution may be a mixture of a basic material, a silica source, and water at a molar ratio of 1:1:50 to 1:25:500, specifically 1:1:100 to 1:1:100. It may be mixed at a molar ratio of 1:10:200, more specifically 1:3:120 to 1:7:180, and in the above range, a shell with a layered crystal structure of layered silicate can be more easily created. there is.

In addition, according to one embodiment of the present invention, the basic material can be used without limitation as long as it can form a layered silicate by performing a crystallization reaction with a silica source. Specifically, it may include a basic sodium material, More specifically, it may include one or more selected from the group consisting of sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium carbonate (Na ₂ CO ₃ ), and sodium hydrogen carbonate (NaHCO ₃ ), and more specifically, hydroxide. It could be sodium.

Additionally, according to one embodiment of the present invention, the water in the reactant solution may be, for example, deionized water.

In addition, according to one embodiment of the present invention, the hydrothermal synthesis in step 2) may be performed at a temperature of 100 to 250 ° C. for 1 to 50 hours, and if the temperature range is satisfied, it is performed at the optimal process time. The efficiency of the process can be increased, and the stability of the reaction can be ensured because the pressure, which can rise as the temperature increases, can be controlled. In addition, when the above synthesis time is satisfied, the layered crystal structure and porous core of the layered silicate can be more easily created, and the problem of energy waste due to unnecessarily prolonged reaction can be prevented.

Specifically, hydrothermal synthesis may be performed for 5 to 24 hours, more specifically 7 to 15 hours, and within the reaction time, the porous structure of the core is maintained more firmly, forming a porous core and a layered shell form. can be synthesized in a more complete form.

Hydrothermal synthesis can be performed by stirring the reactant solution at the above temperature conditions for the above time, or leaving it without stirring, and other conditions for hydrothermal synthesis can be appropriately selected to ensure smooth crystallization reaction. there is.

Additionally, according to an embodiment of the present invention, after forming the layered silicate by hydrothermal synthesis, the step of recovering the layered silicate may be further included.

At this time, generally known separation and recovery methods can be applied without limitation, and the layered silicate can be separated and recovered from the mixture after reaction by any method known to those skilled in the art, such as filtration.

In addition, according to an embodiment of the present invention, after the recovery step, the steps of 4) washing the layered silicate and 5) drying the layered silicate may be further included.

The washing may be performed using water as a washing solvent, and more preferably using deionized water. Additionally, the drying may be performed at a temperature of 50 to 200° C. for 1 to 15 hours. Additionally, the drying may preferably be performed under atmospheric pressure, but changing the pressure conditions is not excluded from the scope of the present invention.

According to another embodiment of the present invention, a porous core; and a shell having a layered structure, wherein the core and shell are made of silica to provide a core-shell type layered silicate. Here, the layered silicate may be synthesized using the above-described synthesis method.

Here, the layered structure forming the shell may represent a flower-like lamellar structure formed during the synthesis of magadite or kenyanite.

In addition, the porous core can be of any shape as long as it is silica having a porous structure with many pores, for example, spherical or oval, and is formed by dissolving and reprecipitating silica from the silica source. Therefore, an amorphous porous silica core formed through dissolution and reprecipitation may also be included in the scope of the present invention.

The layered silicate according to an embodiment of the present invention has excellent adsorption and exchange characteristics, so it may be particularly suitable for adsorption of water or organic molecules and exchange of cationic surfaces. In addition, since it is easy to disperse between layers of the layered structure, it can be used as a reinforcing agent, filler, and nanocomposite for organic materials such as polymers and pharmaceuticals. At this time, when forming the core-shell structure according to the present invention, unlike typical magadite or kenyanite, it contains a porous core, so the adsorption capacity can be improved, and the adsorption or exchange capacity can be greatly improved. Since the specific surface area of the core is high, substances such as polymers, pharmaceuticals, and enzymes inserted between layers can penetrate more easily, and as a result, compatibility with substances such as polymers can be significantly improved.

In addition, unlike the porous core, the surface forms a dense layered shell, so the outside of the particle has a closed structure, so it can be used as a microreactor, drug delivery material, etc.

Since the layered silicate according to the present invention can be controlled as a core-shell structure as described above, its application range is very wide compared to general layered silicate and its industrial applicability is very excellent.

Hereinafter, the present invention will be described in more detail through examples and experimental examples. However, the following examples and experimental examples are for illustrative purposes only and do not limit the scope of the present invention.

Manufacturing Example 1

After preparing a water glass solution with a SiO ₂ content of 8% by weight by diluting water glass (sodium silicate, Youngil Chemical, silica content 28 to 30% by weight, SiO ₂ :Na ₂ O = 3.52 : 1) and distilled water, hexane and 1 A silica precursor solution was prepared by mixing at a volume ratio of :1. The surfactant solitan monooleate (SPAN80) was added to the silica precursor solution at a volume ratio of 5%. Afterwards, it was stirred at 800 rpm using a stirrer to form an emulsion. Acetic acid, a neutralizing agent, was added in a volume ratio of 10% of the mixed solution, and isopropanol, a gelling agent, was added in a volume ratio of mixed solution:gelling agent = 1:2 to prepare silica gel. Ethanol was added to the gelled silica to cause phase separation from the hexane layer, and then washed three times with water. Afterwards, ethanol was added again, washed three times, and dried in an oven at 150°C to prepare spherical silica particles. Relatively large particles were removed from the prepared spherical silica particles using a 63 ㎛ sieve, and then small particles were removed using a 45 ㎛ sieve so that the average particle diameter (D50) was 50 ㎛. At this time, the formation of spherical silica particles can be confirmed by the SEM photograph (100 times magnification) in Figure 1.

Production example 2

Spherical silica particles were prepared in the same manner as Preparation Example 1, except that the stirring speed was changed to 900 rpm. Relatively large particles were removed from the prepared spherical silica particles using a 45 ㎛ sieve, and then small particles were removed using a 25 ㎛ sieve so that the average particle diameter (D50) was 35 ㎛. At this time, the formation of spherical silica particles can be confirmed by the SEM photograph (100x magnification) in FIG. 2.

Comparative Manufacturing Example 1

After preparing 100 ml of water glass solution with 8% by weight SiO ₂ content by diluting water glass (sodium silicate, Youngil Chemical, silica content 28 to 30% by weight, SiO ₂ :Na ₂ O = 3.52 : 1) and distilled water, acetic acid Add 6 ml and gel. Afterwards, the prepared gel was crushed into small pieces using a hand mixer, and then dried under the same conditions as Preparation Example 1 to prepare amorphous silica particles. The formation of amorphous silica particles can be confirmed by the SEM photograph (1000 times magnification) in FIG. 3.

Comparative Manufacturing Example 2

Spherical silica particles were prepared in the same manner as in Preparation Example 1 except that the stirring speed was changed to 3000 rpm, and the average particle diameter (D50) of the spherical silica particles was 5 ㎛.

Example 1

The spherical silica particles, sodium hydroxide, and deionized water of Preparation Example 1 were mixed at a molar ratio of 5:1:150, placed in a Teflon-coated autoclave reactor, and heat treated at 195°C for 12 hours to proceed with the hydrothermal synthesis reaction. . Afterwards, the synthesized product was recovered, washed three times with deionized water, and dried at 150°C for 6 hours to prepare the final layered silicate.

Example 2

Layered silicate was prepared in the same manner as Example 1, except that the hydrothermal synthesis reaction was performed by heat treatment for 15 hours.

Example 3

Layered silicate was prepared in the same manner as Example 1, except that the hydrothermal synthesis reaction was performed by heat treatment for 18 hours.

Example 4

Layered silicate was prepared in the same manner as Example 1, except that the hydrothermal synthesis reaction was performed by heat treatment at 185 °C.

Example 5

Layered silicate was prepared in the same manner as Example 1, except that the spherical silica particles of Preparation Example 2 were used.

Comparative Example 1

Layered silicate was prepared in the same manner as Example 1, except that the amorphous silica particles of Comparative Preparation Example 1 were used.

Comparative Example 2

Layered silicate was prepared in the same manner as in Example 1, except that the spherical silica particles prepared in Comparative Preparation Example 2 were used.

Experiment example

1) Layered silicate structure analysis

In order to confirm the shape of the layered silicate prepared in the above examples and comparative examples, it was observed at a magnification of 1000 to 10,000 times using a scanning electron microscope (S4800, Hitachi), and the results are shown in Figures 4 to 11. It was.

As shown in Figures 4 to 11, the layered silicate prepared according to the synthesis method of the example has a core-shell structure including a porous core and a flower-shaped layered shell, whereas the layered silicate manufactured according to the synthesis method of the comparative example It can be seen that the layered silicate formed only a flower-shaped layered structure of general magadite or kenyanite and did not form a porous core.

Specifically, Figures 4 and 5 are SEM photographs taken with the layered silicate of Example 1 at magnifications of 1,000 and 5,000 times. In the layered silicate of FIGS. 4 and 5, it can be confirmed that a flower-shaped layered shell is formed and a core of a porous structure is formed inside, and the shape can be more easily confirmed in the high-magnification photo of FIG. 5.

Figure 6 is an SEM photograph of the layered silicate of Example 2, Figure 7 is an SEM photograph of the layered silicate of Example 3, Figure 8 is an SEM photograph of the layered silicate of Example 4, and Figure 9 are SEM photographs of the layered silicate of Example 5 taken at different magnifications. In Figures 6 to 9, it can be seen that a porous core and a flower-shaped layered shell are formed as shown in Figures 4 and 5.

In addition, when comparing FIGS. 4 to 7 among the examples, it can be seen that the porous core structure of FIGS. 4 and 5 manufactured using the manufacturing method of Example 1 is maintained most firmly.

In contrast, Figure 10 is an SEM photograph of Comparative Example 1 in which layered silicate was manufactured using amorphous silica particles, and Figure 10 is an SEM photograph of Comparative Example 2 in which spherical silica particles were used as a silica source, but the average particle diameter was less than 20 ㎛. 11, it can be seen that a porous core structure is not observed in the prepared layered silicate, and only a flower-shaped layered structure, which is a typical margardite or kenyanite structure, is formed.

2) X-ray diffraction analysis (XRD)

X-ray diffraction analysis was performed on the layered silicate prepared in Example 1, and the results are shown in FIG. 12. At this time, X-ray diffraction analysis was measured at 2 theta 10° to 70° for 87.5 seconds every 0.02° by powder XRD method using Bruker D4.

As shown in the Through this, it can be confirmed that the layered silicate prepared in the examples of the present invention has a core-shell structure.

Claims (12)

1) mixing a silica source, a basic material, and water to form a reactant solution; and
2) hydrothermally synthesizing the reactant solution to form layered silicate,
The silica source is a spherical silica particle with an average particle diameter (D50) of 20 ㎛ or more,
The spherical silica particles are prepared by mixing a silica material and an organic solvent to prepare a silica precursor solution, adding a neutralizing agent and a gelling agent, and drying the resulting silica gel.
According to paragraph 1,
A method for synthesizing layered silicate, wherein the average particle diameter (D50) of the silica particles is 20 to 60 ㎛.
According to paragraph 1,
A method for synthesizing a layered silicate, wherein the silica particles are spherical secondary silica particles formed by agglomerating silica particles on primary particles.
According to paragraph 1,
A method for synthesizing layered silicate, wherein the basic material, silica source and water are mixed at a molar ratio of 1:1:50 to 1:25:500.
According to paragraph 1,
A layered silicate synthesis method wherein the hydrothermal synthesis is performed at a temperature of 100 to 250 ° C. for 1 to 50 hours.
According to paragraph 1,
The layered silicate synthesis method wherein the hydrothermal synthesis is performed for 5 to 25 hours.
According to paragraph 1,
The basic material is a layered silicate synthesis method comprising at least one selected from the group consisting of sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium carbonate (Na ₂ CO ₃ ), and sodium hydrogen carbonate (NaHCO ₃ ).
According to paragraph 1,
A layered silicate synthesis method wherein the layered silicate is margardite or kenyanite.
According to paragraph 1,
A layered silicate synthesis method wherein the silica source is a reaction product produced by reacting a silica material, a neutralizing agent, and a gelling agent.
According to clause 9,
A method for synthesizing layered silicate, wherein the silica material includes a water glass solution.
A porous core without a layered structure; and
It includes a shell with a layered structure,
A layered silicate wherein the core and shell are made of silica.
According to clause 11,
The layered silicate is margardite or kenyanite.