KR102437453B1 - Preparation method of spherical silica microparticles from Biomass and spherical silica microparticles made by thereof - Google Patents

Abstract

The present invention relates to a method for producing spherical silica particles from biomass and to the spherical silica particles prepared thereby, the method for producing spherical silica particles from biomass is to prepare a silicate solution by reacting biomass with an aqueous alkali solution. Step 1; a second step of preparing a first mixture by mixing polyethylene glycol (PEG) with the silicate solution; a third step of precipitating silica particles by adding an acid to the first mixture, followed by stirring; and a fourth step of washing with distilled water after collecting the silica particles precipitated through the third step. In this case, the silicate solution of the first step may be extracted through reduced pressure filtration, and the silica particles of the fourth step may be collected by vacuum filtration or centrifugation. In addition, the present invention is characterized in that by controlling the process temperature of the third step, the size of the spherical silica particles is controlled. When the third step is performed at a lower temperature than room temperature within the range of 1°C to 100°C, micrometer silica particles can be prepared, and when the third step is performed at room temperature or higher, nanometer silica particles can be prepared . Since the present invention uses an aqueous alkali solution having a low temperature and a low concentration, there are advantageous advantages in terms of process convenience and cost reduction.

Description

Method for producing spherical silica particles from biomass and spherical silica particles prepared thereby

The present invention relates to a method for manufacturing silica (silicon dioxide, SiO ₂ ) particles, and to spherical silica particles prepared thereby, and more particularly, to a spherical and size-controlled silica particle using biomass, PEG and acid. It relates to a method and to spherical silica particles prepared thereby.

[Project unique number] 319109-02

[Name of Ministry] Ministry of Agriculture, Food and Rural Affairs

[Research and Management Specialized Institution] Agriculture, Forestry and Food Technology Planning and Evaluation Institute

[Research project name] Agricultural products safe distribution and consumption technology development project

[Research project name] Development and commercialization of high-functional, high-value-added industrial material processing technology for rice husks

[Contribution rate] 1/2

[Organization] Korea Ceramic Technology Institute

[Research Period] 2019.09.25. ~ 2021.09.24.

[Project unique number] 20183030091950

[Ministry name] Ministry of Trade, Industry and Energy

[Research and Management Specialized Institution] Korea Energy Technology Evaluation and Planning

[Research project name] Energy technology development project-Renewable energy core technology

[Research project name] Bio-sugar production using rice husk and added value of silica by-product

[Contribution rate] 1/2

[Organization] Sugar N Co., Ltd.

[Research period] 2018.10.01. ~ 2021.09.30.

It is known that a large amount of silica is present in biomass, particularly ligrocellulosic biomass, and in particular, it is known that rice husk or rice straw contains silica corresponding to about 10% by weight.

Silica derived from this biomass is a silicon raw material (J.A.Amick, J. Electrochem. Soc.129,864 (1982); L.P.Hunt, J. Electrochem. Soc. 131,1683 (1984)), a raw material of silicon carbide (R.V.Krishnarao, J. Am. Chem. Soc. 74,2869 (1991)), cement additives (Jose James, et. al., J. Sci. Ind. Res. 51, 383 (1992)), etc. have been studied for various uses.

In order to obtain silica from biomass, research on technology development to remove organic matter (cellulose, hemicellulose, lignin, etc.) from biomass has been continuously conducted, but these conventional methods only focus on producing silica, It was difficult to control the shape of silica, so there was a limit to industrialization and commercialization.

J. A. Amick, J. Electrochem. Soc.129,864 (1982); L. P. Hunt, J. Electrochem. Soc. 131,1683 (1984) R.V.Krishnarao, J. Am. Chem. Soc. 74,2869 (1991) Jose James, et. al., J. Sci. Ind. Res. 51, 383 (1992)

The present invention relates to a method for manufacturing silica (silicon dioxide, SiO ₂ ) particles, and to spherical silica particles prepared thereby, and to a method for manufacturing spherical and size-controlled silica particles using biomass, PEG and acid. .

One embodiment of the present invention for achieving the object as described above is a method for producing spherical silica particles from biomass, comprising: a first step of preparing a silicate solution by reacting the biomass with an aqueous alkali solution; a second step of preparing a first mixture by mixing polyethylene glycol (PEG) with the silicate solution; a third step of precipitating silica particles by adding an acid to the first mixture, followed by stirring; and a fourth step of washing with distilled water after collecting the silica particles precipitated through the third step. In this case, the silicate solution of the first step may be extracted through reduced pressure filtration, and the silica particles of the fourth step may be collected by vacuum filtration or centrifugation.

The biomass of the first step may be at least one selected from rice bran, rice husk, rice straw, reeds, corn leaves and corn stalks.

The aqueous alkali solution of the first step is preferably 0.1 to 1M sodium hydroxide (NaOH) aqueous solution.

The first step is preferably carried out in the range of 60 ℃ ~ 100 ℃ temperature.

The PEG of the second step preferably has a number average molecular weight of 1,500 to 20,000.

The acid used in the third step may be at least one selected from acetic acid, hydrochloric acid, nitric acid, and sulfuric acid, and the acid may be added to the first mixture to have a pH value of 6.0 to 8.0.

In addition, it is possible to control the size of the spherical silica particles produced by adjusting the process temperature of the third step, and the stirring of the third step is performed for at least 30 minutes or more and within 24 hours, and 1 to 100 ° C. It can be carried out in a temperature range. At this time, the spherical silica particles of 0.8 to 5 micrometers may be produced at 1°C or more and less than 25°C, and spherical silica particles of 50 to 900 nanometers may be manufactured at 25°C or more and 100°C or less.

After the fourth step, after drying the washed silica particles, heat treatment at a temperature of 500 ~ 700 ℃; may further include.

Meanwhile, another embodiment of the present invention is a spherical silica particle prepared according to the above method.

In the present invention, by preparing a silicate solution using an aqueous alkali solution at a temperature of 100° C. or less and a low concentration, it is possible to separate silica through a reduced pressure filtration method, and it can also be easy to wash the separated silica. Since the present invention uses an aqueous alkali solution at a low temperature and a low concentration, it is advantageous in terms of process convenience and cost reduction.

In addition, in the present invention, spherical and size-controlled silica particles can be prepared by adding a PEG polymer and controlling the temperature of the manufacturing process.

1 is a flowchart of a method for preparing silica particles of the present invention.
2 is a result of observing the silica particles of Examples 1 to 4 with a scanning electron microscope (SEM).
3 is a result of observing the silica particles of Comparative Example with a scanning electron microscope (SEM).

Before describing in detail through preferred embodiments of the present invention, terms or words used in the claims of the present specification should not be construed as being limited to conventional or dictionary meanings, but meanings consistent with the technical spirit of the present invention. and should be interpreted as a concept.

Throughout this specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

1 is a flowchart of a silica manufacturing method according to the present invention. Referring to FIG. 1 , the method for preparing spherical silica particles from biomass according to the present invention includes a first step of preparing a silicate solution by reacting the biomass with an aqueous alkali solution; a second step of preparing a first mixture by mixing polyethylene glycol (PEG) with the silicate solution; a third step of precipitating silica particles by adding an acid to the first mixture, followed by stirring; and a fourth step of washing with distilled water after collecting the silica particles precipitated through the third step. At this time, the silicate solution of the first step is extracted through reduced pressure filtration, and the silica particles of the fourth step are collected by vacuum filtration or centrifugation.

In the present invention, it is preferable that the silica particles of the fourth step are collected by vacuum filtration. The reduced pressure filtration is a filtration method in which the pressure inside the filter paper is manipulated to be lower than atmospheric pressure and suction occurs. By making it low, the principle that filtration proceeds by the pressure difference is used. When vacuum filtration is used, the filtration rate can be increased compared to the case of relying on atmospheric pressure, so a large amount of material can be filtered in a short time, high-purity filtration can be performed stably, and the cost is low. have.

In one embodiment, the first step is a step of preparing a silicate solution by reacting the biomass with an aqueous alkali solution. The biomass may be at least one selected from rice bran, rice hull, rice bran, reed, corn leaf, and corn stalk.

When an aqueous alkali solution is added to the biomass in the first step, a silicon component is extracted from the biomass to produce sodium metasilicate (Na2SiO3) or a silicate such as sodium metasilicate combined with crystal water (Na2SiO3·nH2O). . At this time, it is preferable to add 100-200 ml of aqueous alkali solution to 100 g of biomass. As the aqueous alkali solution, an alkali material such as sodium hydroxide, lithium hydroxide, calcium hydroxide or sodium carbonate may be dissolved in water, but is not limited thereto.

In the first step, the aqueous alkali solution is preferably 0.1 to 1M sodium hydroxide (NaOH) aqueous solution. When the concentration of the aqueous alkali solution is higher than 1M, a large amount of organic matter may be leached out together with the silicate solution. On the other hand, when the concentration of the aqueous alkali solution is lower than 0.1 M, it may be difficult to prepare the silicate solution itself.

In addition, the first step is preferably carried out at a temperature of 60 ℃ ~ 100 ℃. When the temperature is lower than 60° C., it may be difficult to prepare the silicate solution itself. On the other hand, when the temperature exceeds 100 °C, a large amount of organic matter may be leached out together in the silicate solution.

In the first step, 0.1 to 1M sodium hydroxide (NaOH) aqueous solution is used or when the first step is performed at a temperature of 60°C to 100°C, as well as a large amount of organic components in the silicate solution as described above. In the case of extraction, silica particles may be collected by centrifugation in the fourth step.

The present invention is advantageous in terms of unit cost reduction of the entire process by preparing a silicate solution using a low temperature of 60 ° C. to 100 ° C. or less and a low concentration of an aqueous alkali solution in the range of 0.1 M to 1 M in the first step, and the fourth By using the vacuum filtration method in the step, the produced silica can be easily separated and washed.

In one embodiment, the second step is a step of preparing a first mixture by mixing PEG with the silicate solution prepared in the first step. In this case, the number average molecular weight of the PEG (hereinafter referred to as 'molecular weight') is preferably 1,500 to 20,000. If the ethylene oxide chain constituting the PEG polymer is sufficient, it is judged to be advantageous for controlling the spherical shape of silica. When PEG with a low molecular weight is used, it may be difficult to control the sphericity of silica particles due to insufficient ethylene oxide chains.

On the other hand, Na ₂ O in the sodium silicate solution may contain up to 10.6%, SiO ₂ up to 26.5%, the PEG is used in an amount of 0.1 to 2.0 times the weight of the silica component present in the silicate prepared in the first step. It is preferable to be When the amount of PEG used is less than 0.1 times, it may be difficult to control the spherical shape of the silica particles.

In one embodiment, the third step is a step of precipitating silica particles by adding an acid to the first mixture, followed by stirring. In order to produce silica from silicate, it is necessary to adjust the pH using an acid. At this time, the acid used in the third step may be at least one selected from acetic acid, hydrochloric acid, nitric acid, and sulfuric acid, and it is preferable to use acetic acid, and the acid is added to the first mixture to have a pH value of 6.0 to 8.0 it is preferable

When the pH is 6.0 or less, organic matter present in the silicate solution is precipitated together, resulting in a problem that the speed is inhibited during the vacuum filtration in the fourth step. On the other hand, when the pH is adjusted to 8.0 or higher, it may be difficult to control the spherical shape of the produced silica particles.

The present invention is characterized in that the size of the silica particles produced by controlling the process temperature of the third step is controlled. When the third step is performed at a lower temperature than room temperature, micrometer silica particles can be prepared, and when the third step is performed at room temperature or higher, nanometer silica particles can be prepared. That is, as the temperature of the third step increases, the size of the produced silica particles becomes smaller.

In this case, the stirring in the third step is performed at a speed of 100 to 1,500 rpm for a time period of 30 minutes or more and within 24 hours, and is preferably performed in a temperature range of 1 to 100 ° C. If the temperature is lower than 1 ℃, the silicate solution is frozen, it may be difficult to proceed or stir the reaction.

According to an embodiment of the present invention, when the temperature of the third step is controlled from 1°C to less than 25°C, it was confirmed that the size of the silica particles has a size of 1 to 2 micrometers. On the other hand, when the temperature was adjusted to 25°C to 100°C, the size of the silica particles was in the range of 100 to 800 nanometers. That is, within the range of 1°C to 100°C, the size of the prepared spherical silica particles increases in micrometer units as the temperature of the third step of the present invention is lower than room temperature, but as the temperature is higher than room temperature, the silica particles become denser. It was confirmed that it was arranged, and the size became smaller in nanometers and had a relatively clear spherical shape.

On the other hand, in one embodiment, the fourth step is a step of washing with distilled water after collecting the silica particles precipitated through the third step. After the fourth step, after drying the washed silica particles, it may further include the step of heat-treating at a temperature of 500 ~ 700 ℃. A temperature of 500° C. or higher is preferable for removing the residual polymer, and a temperature of 700° C. or lower is preferable for preventing excessive particle agglomeration.

Hereinafter, it will be described with a focus on specific embodiments of the present invention. However, the scope of the present invention is not limited only to the following examples, these examples are only presented by way of example to describe the present invention in more detail, and those of ordinary skill in the art may It is intended to disclose that various modified forms of the described content can be implemented.

[Example 1]

50 g of rice husk is put in a 0.5 M aqueous alkaline solution (NaOH) solution, and after reacting at a temperature of 80° C. for 3 hours, only the silicate solution, which is a liquid component, is extracted and separated by vacuum filtration to prepare a silicate solution. (Step 1)

Then, 3.0 g of a PEG polymer having a molecular weight of 3,000 is dissolved in 400 ml of silicate solution. (Step 2)

The temperature of the solution prepared in the second step is adjusted to 5° C., and acetic acid is added until the pH is 6.5. The silica particles are precipitated by stirring for 2 hours while maintaining the temperature of 5°C. (Step 3)

After stirring, the precipitate was collected by vacuum filtration, and washed with distilled water. (Step 4).

After drying, 6.0 g of spherical silica particles were prepared by heat treatment at a temperature of 550° C. in air for 2 hours. (Step 5).

[Example 2]

It was prepared in the same manner as in Example 1, but the temperature of the third step was adjusted to 25° C. to prepare spherical silica particles.

[Example 3]

Prepared in the same manner as in Example 1, except that the temperature of the third step was adjusted to 60 ℃ to prepare spherical silica particles

[Example 4]

Prepared in the same manner as in Example 1, but the temperature of the third step was adjusted to 80 ℃ to prepare spherical silica particles

[Comparative example]

It was prepared in the same manner as in Example 1, but spherical silica particles were prepared without adding a PEG polymer in the second step.

[Experimental Example 1]

In order to confirm whether spherical silica particles are prepared according to the addition of PEG, the results according to Example 1 and Comparative Example are shown in Table 1, and the results of observation of the silica particles of Example 1 by SEM are shown in FIG. The results of observing the silica particles of the example by SEM are shown in FIG. 3 .

PEG 3rd stage temperature shape Silica particle size Example 1 3.0g 5℃ rectangle 1-2 micrometers comparative example - irregular irregular

As can be seen in Table 1 above, in the case of the comparative example in which PEG was not added, the silica particles prepared did not have a spherical shape and had an irregular size, whereas in the case of Example 1 in which PEG was added, it can be confirmed that spherical silica particles were prepared. .

[Experimental Example 2]

Examples 1 to 4 were prepared as shown in Table 2 below in order to confirm the size change of the silica particles prepared according to the temperature change in the third step in the method for producing silica particles of the present invention, and Examples 1 to 4 The results of observation of the silica particles by SEM are shown in FIG. 2 .

PEG 3rd stage temperature shape Silica particle size Example 1 3.0g 5℃ rectangle 1-2 micrometers Example 2 25℃ 500-800 nanometers Example 3 60℃ 200-550 nanometers Example 4 80℃ 100-300 nanometers

As can be seen in Table 2, in the case of Example 1 in which the temperature of the third step of the present invention is within the range of 1°C or more and less than 25°C, it can be seen that the size of the silica particles produced is in micrometer units. In addition, in the case of Examples 2 to 4, in which the temperature of the third step is 25°C or more and 100°C or less, nanometer-sized silica particles were prepared, and it was confirmed that the size of the prepared silica particles decreased step by step as the temperature increased. can

Claims (12)

A first step of preparing a silicate solution by reacting the biomass with an aqueous alkali solution; a second step of preparing a first mixture by mixing polyethylene glycol (PEG) with the silicate solution; a third step of precipitating silica particles by adding an acid to the first mixture, followed by stirring; and a fourth step of washing with distilled water after collecting the silica particles precipitated through the third step;
The first step is carried out in the range of 60 ℃ ~ 100 ℃ temperature, the aqueous alkali solution of the first step is 0.1 ~ 1M sodium hydroxide (NaOH) aqueous solution,
The stirring of the third step is performed in a temperature range of 1 to 100° C. for a time period of not less than 30 minutes and within 24 hours, and controlling the size of the spherical silica particles by controlling the process temperature of the third step, and not less than 1° C. 25 A method for producing spherical silica particles from biomass, characterized in that 0.8-5 micrometers of spherical silica particles are produced at less than ℃, and 50-900 nanometers of spherical silica particles are produced at 25℃ or more and 100℃ or less . The method of claim 1,
The biomass of the first step is at least one selected from rice bran, rice husk, rice straw, reeds, corn leaves and corn stalks, a method for producing spherical silica particles from biomass. delete The method of claim 1,
The silicate solution of the first step is extracted through reduced pressure filtration,
The method for producing spherical silica particles from biomass, characterized in that the silica particles of the fourth step are collected by vacuum filtration or centrifugation. delete The method of claim 1,
The PEG is a method for producing spherical silica particles from biomass, characterized in that the number average molecular weight is 1,500 to 20,000. The method of claim 1,
The acid used in the third step may be at least one selected from acetic acid, hydrochloric acid, nitric acid, and sulfuric acid,
The method for producing spherical silica particles from biomass, characterized in that the acid is added to the first mixture to have a pH value of 6.0 to 8.0. According to claim 1, After the fourth step,
After drying the washed silica particles, heat treatment at a temperature of 500 ~ 700 ℃; Method for producing spherical silica particles from biomass, characterized in that it further comprises further comprising. delete delete delete delete

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