KR102314406B1 - Method for manufacturing magnetic silica particle - Google Patents

Abstract

The present invention relates to silica particles having excellent treatment efficiency in a water treatment process and easy recovery after use.

Description

Method for producing silica particles having magnetism TECHNICAL FIELD

The present invention relates to a method for producing silica particles having magnetism.

Contaminants such as organic dyes present in water can arise from dyeing wastewater as well as from various manufacturing industries. In addition, since heavy metal components accumulate not only in the human body but also in fish and shellfish and cause serious diseases, an appropriate removal method is required. These contaminants can be removed by separation and purification processes such as adsorption and extraction, and activated carbon is traditionally used in the adsorption process. However, since activated carbon is relatively expensive, a technique for synthesizing a material such as silica having a large surface area from an inexpensive raw material is being developed for the development of a more economical adsorbent. Among the existing raw materials for synthesizing silica, organometallic compounds have a high unit price, so when an economical raw material such as water glass is used, it has a much more advantageous advantage for industrialization. However, in the water treatment process, if the adsorbent is not properly recovered after use, it may act as an additional pollutant itself, a problem to be overcome.

Since the porous powder has a large specific surface area, it is easy to remove by adsorption of organic substances and heavy metals. Accordingly, the development of catalyst carriers, photocatalysts, adsorbents, etc. utilizing porous powder has been actively conducted. However, in the process of using the porous powder in the water treatment process, the porous powder itself acts as a contaminant, and an appropriate technique such as centrifugation is required for separation and removal by recovery. However, when the size of the porous powder is very small, the rotation speed required for centrifugation increases and energy consumption increases, such as taking a long time, and some powder may remain in water and thus it may be difficult to completely remove it.

In the case of micrometer-sized powder, natural precipitation by gravity is possible, but it can be said that the time required for precipitation is long, which makes it impractical. In addition, when the powder has a size distribution, even if the median diameter or average particle diameter corresponds to a micrometer region, powders having a size of some sub-micrometer regions may coexist, and natural sedimentation may be difficult in such a size region. .

Accordingly, there is a need for a technology capable of effectively recovering the porous powder used in the water treatment process. This is commonly required for the practical use of adsorption and photocatalytic processes.

An object of the present invention is to provide silica particles having excellent treatment efficiency in the water treatment process and easy recovery after use.

However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

An exemplary embodiment of the present invention comprises the steps of preparing a solution for forming silica having magnetic properties by mixing an aqueous solution of silicic acid and an iron oxide solution; forming an emulsion by emulsifying the solution for forming silica having the magnetic properties; heating the emulsion to form a gel; and heat-treating the gel to form silica particles containing iron oxide.

The method for producing silica particles according to an exemplary embodiment of the present invention can easily produce silica particles having excellent treatment efficiency in a water treatment process and easy recovery after use.

However, the effects of the present invention are not limited to the above-described effects, and may be variously expanded without departing from the spirit and scope of the present invention.

1 is a view schematically showing a method of manufacturing silica particles having magnetism according to an embodiment of the present invention.
Figure 2a is a photograph taken through a scanning electron microscope (SEM) of the silica particles prepared according to Example 1 of the present invention, Figure 2b is a graph showing the particle size distribution of the silica particles prepared according to Example 1.
Figure 3a is a photograph taken through a scanning electron microscope (SEM) of the silica particles prepared according to Example 2 of the present invention, Figure 3b is a graph showing the particle size distribution of the silica particles prepared according to Example 2, Figure 3c shows the EDS result data of the silica particles prepared according to Example 2, Figure 3d shows the FT-IR spectrum of the silica particles prepared according to Example 2.
4 shows XRD data of silica particles prepared in Examples 1 and 2 of the present invention.
Figure 5a is a photograph taken through a scanning electron microscope (SEM) of the silica particles prepared according to Example 3 of the present invention, Figure 5b is a graph showing the particle size distribution of the silica particles prepared according to Example 3.
Figure 6a is a photograph taken through a scanning electron microscope (SEM) of the silica particles prepared according to Example 4 of the present invention, Figure 6b is a graph showing the particle size distribution of the silica particles prepared according to Example 4.
7 is a photograph taken through a scanning electron microscope (SEM) of the silica particles prepared according to Comparative Example 1.
Figure 8a is a photograph taken through a scanning electron microscope (SEM) of the silica particles prepared according to Example 5 of the present invention, Figure 8b is a graph showing the particle size distribution of the silica particles prepared according to Example 5.
Figure 9a is a photograph taken through a scanning electron microscope (SEM) of the silica particles prepared according to Example 6 of the present invention, Figure 9b is a graph showing the particle size distribution of the silica particles prepared according to Example 6.
Figure 10a is a graph showing the concentration of methylene blue according to the adsorption time of the silica particles prepared according to Example 1 of the present invention, Figure 10b is methylene according to the adsorption time of the silica particles prepared according to Example 2 of the present invention It is a graph showing the concentration of blue, Figure 10c is a graph showing the concentration of methylene blue according to the adsorption time of the silica particles prepared according to Example 3 of the present invention, Figure 10d is a graph prepared according to Example 4 of the present invention It is a graph showing the concentration of methylene blue according to the adsorption time of silica particles.
11a and 11b are graphs showing the concentration of methylene blue according to the UV irradiation time of the silica particles prepared according to Example 5 of the present invention.
12 is a photograph taken using a magnet after completion of photocatalytic performance evaluation of silica particles prepared according to Example 5 of the present invention.

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

Throughout this specification, when a member is said to be “on” another member, this includes not only a case in which a member is in contact with another member but also a case in which another member is present between the two members.

Hereinafter, the present invention will be described in more detail.

1 is a view schematically showing a method of manufacturing silica particles having magnetism according to an embodiment of the present invention.

An exemplary embodiment of the present invention comprises the steps of preparing a solution for forming silica having magnetic properties by mixing an aqueous solution of silicic acid and an iron oxide solution; forming an emulsion by emulsifying the solution for forming silica having the magnetic properties; heating the emulsion to form a gel; and heat-treating the gel to form silica particles containing iron oxide.

Through the method for producing silica particles according to an exemplary embodiment of the present invention, silica particles having excellent treatment efficiency in the water treatment process and easy recovery after use can be easily produced.

According to an exemplary embodiment of the present invention, the method for producing silica particles having magnetism may include preparing a silicic acid solution from a silica precursor solution, and mixing the silicic acid solution with water to prepare the silicic acid aqueous solution. .

By passing the silica precursor solution through an ion exchange resin, the silicic acid solution may be prepared. Specifically, the silica precursor may be sodium silicate, and the sodium silicate may be passed through an ion exchange resin to remove sodium ions and obtain a silicic acid solution.

In the step of preparing the aqueous solution of silicic acid, a mixing ratio (eg, volume ratio) of the silicic acid solution and the water may be adjusted to control the surface shape and specific surface area of silica particles, which are final products.

According to an exemplary embodiment of the present invention, in the step of preparing the aqueous solution of silicic acid, the silicic acid solution and the water may be mixed in a volume ratio of 1:1 to 1:10. The prepared silicic acid solution may be mixed with water to form the silicic acid aqueous solution. At this time, in order to prepare an aqueous silicic acid solution, the silicic acid solution and water are mixed with 1:1 to 1:10, 1:2 to 1:8, 1:3 to 1:7, 1:4 to 1:5, 1:1. to 1:6, or 1:5 to 1:10 by volume.

In the step of preparing the silicic acid aqueous solution, by mixing the silicic acid solution and the water in the above-described volume ratio, the specific surface area of the produced silica particles can be effectively increased. In addition, when the volume ratio of the silicic acid solution and water is within the aforementioned range, it is possible to suppress excessive deformation of the particle structure of the silica particles to be produced.

According to an exemplary embodiment of the present invention, a solution for forming magnetic silica may be prepared by mixing the prepared silicic acid solution and iron oxide solution. The silica particles prepared through the solution for forming silica having the magnetic properties may be used as an adsorbent to adsorb contaminants and the like in the water treatment process.

In addition, by mixing the iron oxide solution with the silicic acid solution, it is possible to impart magnetism to the produced silica particles. After the silica particles imparted with magnetism are treated in the water treatment process, they can be easily recovered from the water treated water using a magnet.

The iron oxide solid content of the iron oxide solution may be 6% or more and 40% or less.

According to an exemplary embodiment of the present invention, in the step of preparing the solution for forming the magnetic silica, the aqueous solution of silicic acid and the iron oxide solution may be mixed in a volume ratio of 1:1 to 10:1. Specifically, in order to prepare the solution for forming the magnetic silica, the aqueous solution of silicic acid and the iron oxide solution are mixed with 1.5:1 to 10:1, 2:1 to 10:1, 3:1 to 10:1, or 5 It can be mixed in a volume ratio of :1 to 10:1.

In the step of preparing the solution for forming silica having the magnetism, by mixing the aqueous solution of silicic acid and the iron oxide solution in the above-described volume ratio, appropriate magnetism is imparted to the silica particles to be prepared, so that the silica particles can be easily recovered after water treatment have. In addition, when the volume ratio of the aqueous solution of silicic acid and the iron oxide solution is within the above-mentioned range, it is possible to effectively suppress a decrease in the water treatment performance of the silica particles produced.

According to an exemplary embodiment of the present invention, in the step of preparing a solution for forming silica having a magnetic property, a titanium dioxide solution may be additionally mixed with a mixture of the silicic acid aqueous solution and the iron oxide solution. That is, the silica-forming solution may be a mixture of the silicic acid aqueous solution, the iron oxide solution, and the titanium dioxide solution. Through this, the solution for forming silica may have photocatalytic activity and magnetism.

As the titanium dioxide solution is added to the solution for forming silica having magnetic properties, the silica particles prepared from the solution for forming silica may have photocatalytic performance in addition to adsorption performance. Specifically, titanium dioxide (TiO ₂ ) contained in the prepared silica particles does not change even when exposed to light and can be used semi-permanently, and may be a photocatalyst that oxidizes all organic materials and decomposes into carbon dioxide and water.

The titanium dioxide solid content of the titanium dioxide solution may be 6% or more and 40% or less.

That is, the silica particles prepared from the solution for forming silica having photocatalytic activity and magnetism, which is a mixture of the aqueous solution of silicic acid, the iron oxide solution, and the titanium dioxide solution, can serve as an adsorbent and a photocatalyst in the water treatment process, and It can be easily recovered using a magnet after water treatment.

According to an exemplary embodiment of the present invention, in the solution for forming silica having photocatalytic activity and magnetism, a volume ratio of the aqueous silicic acid solution and the titanium dioxide solution may be 1:1 to 3:1. Specifically, in order to prepare a solution for forming silica having photocatalytic activity and magnetism, the aqueous solution of silicic acid and the titanium dioxide solution are mixed with 1:1 to 3:1, 1.5:1 to 3:1, or 1:1 to 2 It can be mixed in a volume ratio of :1.

By adjusting the volume ratio of the aqueous solution of silicic acid and the titanium dioxide solution contained in the solution for forming silica having photocatalytic activity and magnetism to the above-mentioned range, photocatalytic performance can be effectively imparted to the produced silica particles, and the produced silica particles can effectively increase the specific surface area of

According to an exemplary embodiment of the present invention, in the solution for forming silica having photocatalytic activity and magnetism, a volume ratio of the iron oxide solution and the titanium dioxide solution may be 1:1 to 1:5. Specifically, in order to prepare the solution for forming silica, the iron oxide solution and the titanium dioxide solution are mixed with 1:1 to 1:5, 1:1 to 1:4, 1:2 to 1:5, or 1:4. to 1:5 in a volume ratio.

By adjusting the volume ratio of the iron oxide solution and the titanium dioxide solution included in the solution for forming silica having photocatalytic activity and magnetism to the above-described range, photocatalytic performance and magnetism can be effectively imparted to the produced silica particles.

According to an exemplary embodiment of the present invention, in the step of forming the emulsion, the solution for forming the silica may be emulsified using an emulsifier. As the emulsifier, an emulsifier used in the art may be used. For example, tetradecane containing Abil EM 90 emulsifier may be used as the emulsifier, but the type of the emulsifier is not limited.

According to an exemplary embodiment of the present invention, the step of forming the gel may be performed at a temperature of 85 ℃ or more and 95 ℃ or less. By heating the emulsion, the emulsion can be gelled. Specifically, by heating the emulsion, it is possible to form a thin outer film made of silica gel on the outside of the emulsion. By adjusting the temperature at which the emulsion is heated to the above-mentioned range, the emulsion can be more easily gelled.

According to an exemplary embodiment of the present invention, the heat treatment may be performed at a temperature of 450° C. or higher and 550° C. or lower. By heat-treating the gel, silica particles can be produced. Specifically, in the heat treatment step, the gel may be calcined, whereby moisture or organic matter remaining from the gel may be evaporated or removed, and silica particles may be manufactured. In addition, the iron oxide particles are more strongly bound to the silica gel through calcination, so that the physical bonding strength of the two components can be stronger than before calcination.

The heat treatment may be performed for 5 to 20 hours. When the process time of the heat treatment is within the above range, the silica particles may be sufficiently formed from the gel, and the manufacturing time may be shortened.

According to an exemplary embodiment of the present invention, the forming of the gel and the heat treatment may be performed continuously. For example, the emulsion may be heated to form the gel, and then the gel may be continuously heat treated. By successively performing the step of forming the gel and the heat treatment step, it is possible to reduce the manufacturing time and process difficulty of the silica particles.

According to an exemplary embodiment of the present invention, the prepared silica particles may have a spherical shape. In addition, the silica particles may be porous. Specifically, the silica particles may have a porous surface. Silica particles having a spherical shape and a porous surface may easily perform a photocatalytic function of an adsorbent during water treatment.

Hereinafter, examples will be given to describe the present invention in detail. However, the embodiments according to the present invention may be modified in various other forms, and the scope of the present invention is not to be construed as being limited to the embodiments described below. The embodiments of the present specification are provided to more completely explain the present invention to those of ordinary skill in the art.

Preparation of silica particles

Example 1

Sodium silicate (water glass, Na ₂ O(SiO ₂ ) _x xH2O%) as a silica precursor was purchased from Samchun Chemical. Deionized water (18.2MΩcm ^-1 ) was prepared using a distilled water system (Millipore).

Sodium silicate and deionized water were mixed in a volume ratio of 1:2, and the mixture was passed through an ion exchange resin (amberlite IR 120, hydrogen form) purchased from Sigma-Aldrich to obtain a silicic acid solution. Thereafter, an aqueous solution of silicic acid was prepared by mixing the silicic acid solution and deionized water in a volume ratio of 3:4.

Thereafter, the prepared aqueous solution of silicic acid and an iron oxide solution (solid content 20%) purchased from US Research Nanomaterials were mixed in a volume ratio of 10:1 to prepare a solution for forming magnetic silica. Emulsion droplets were prepared by emulsifying the solution for silica formation with tetradecane (Beyond Industries Limited) containing Abil EM 90 emulsifier (Cosnet) using a mechanical homogenizer.

Thereafter, in a complex fluid system without the use of a polymer mold, the prepared emulsion droplets were heated at a temperature of 90° C. for 1.5 hours to form a gel. Thereafter, the gel was calcined at a temperature of 500° C. for 5 hours to prepare silica particles.

Example 2

In Example 1, silica particles were prepared in the same manner as in Example 1, except that the volume ratio of the silicic acid aqueous solution and the iron oxide solution was adjusted to 5:1.

Example 3

In Example 1, silica particles were prepared in the same manner as in Example 1, except that the volume ratio of the silicic acid aqueous solution and the iron oxide solution was adjusted to 3:1.

Example 4

In Example 1, silica particles were prepared in the same manner as in Example 1, except that the volume ratio of the silicic acid aqueous solution and the iron oxide solution was adjusted to 2:1.

Example 5

A silicic acid aqueous solution was prepared in the same manner as in Example 1, and the same iron oxide solution used in Example 1 was prepared. In addition, a titanium dioxide solution (15% solid content) purchased from Nanostructured and Amorphous Materials was prepared.

A solution for forming silica was prepared by mixing an aqueous silicic acid solution, a titanium dioxide solution, and an iron oxide solution in a volume ratio of 3:0.5:2. Then, in the same manner as in Example 1, silica particles were prepared from the solution for forming silica.

Example 6

In Example 5, silica particles were prepared in the same manner as in Example 5, except that the volume ratio of the aqueous silicic acid solution, the titanium dioxide solution, and the iron oxide solution was adjusted to 3:2:2.

Comparative Example 1

In Example 1, silica particles were prepared in the same manner as in Example 1, except that the volume ratio of the silicic acid aqueous solution and the iron oxide solution was adjusted to 3:4.

Evaluation of the physical properties of silica particles

Analysis of the shape and particle size distribution of silica particles

The silica particles prepared in Examples 1 to 6 and Comparative Example 1 were photographed using a scanning electron microscope (FE-SEM, Hitachi-S4700), and particle size distribution of the silica particles using the photographed scanning electron microscope image. was calculated.

Component Analysis of Silica Particles

Using an energy dispersive X-ray spectrometer (EDS; Energy Dispersive X-ray Spectroscopy) and a Nicolet FT-IR spectrometer (Thermo Fisher Scientific co. Ltd), the composition of the silica particles prepared in Example 2 was confirmed.

In addition, XRD analysis of the silica particles prepared in Examples 1 and 2 was performed using an X-ray diffraction apparatus (XRD Ultima IV, Rigaku Co.).

Figure 2a is a photograph taken through a scanning electron microscope (SEM) of the silica particles prepared according to Example 1 of the present invention, Figure 3a is a scanning electron microscope (SEM) of the silica particles prepared according to Example 2 of the present invention ) is a photograph taken through, Figure 5a is a photograph taken through a scanning electron microscope (SEM) of the silica particles prepared according to Example 3 of the present invention, Figure 6a is a photograph prepared according to Example 4 of the present invention It is a photograph taken through a scanning electron microscope (SEM) of silica particles, Figure 7 is a photograph taken through a scanning electron microscope (SEM) of the silica particles prepared according to Comparative Example 1, Figure 8a is an embodiment of the present invention 5 is a photograph taken through a scanning electron microscope (SEM), FIG. 9a is a photograph taken through a scanning electron microscope (SEM) of the silica particles prepared according to Example 6 of the present invention.

Referring to FIGS. 2A, 3A, 5A, 6A, 8A, and 9A, the silica particles prepared in Examples 1 to 6 of the present invention have an overall spherical shape, and have a porous surface. confirmed that.

On the other hand, referring to FIG. 7 , it was confirmed that the silica particles prepared in Comparative Example 1 in which the volume ratio of the aqueous silicic acid solution and the iron oxide solution were adjusted to 3:4 did not maintain a spherical shape. When the content of iron oxide is excessively increased, it was confirmed that the shape of the particles deviated much from the sphere.

Figure 2b is a graph showing the particle size distribution of the silica particles prepared according to Example 1, Figure 3b is a graph showing the particle size distribution of the silica particles prepared according to Example 2, Figure 5b is a graph showing the particle size distribution of the silica particles prepared according to Example 3 It is a graph showing the particle size distribution of silica particles, Figure 6b is a graph showing the particle size distribution of the silica particles prepared according to Example 4, Figure 8b is a graph showing the particle size distribution of the silica particles prepared according to Example 5, 9B is a graph showing the particle size distribution of silica particles prepared according to Example 6.

2b, 3b, 5b, 6b, 8b, and 9b, by adjusting the relative volume ratio between the silicic acid aqueous solution, iron oxide solution, and titanium dioxide contained in the silica-forming solution, the particle diameter of the silica particles produced It was confirmed that the distribution can be controlled in various ways.

Figure 3c shows the EDS result data of the silica particles prepared according to Example 2, Figure 3d shows the FT-IR spectrum of the silica particles prepared according to Example 2. In addition, Figure 4 shows the XRD data of the silica particles prepared in Examples 1 and 2 of the present invention.

Referring to FIG. 3c , it was confirmed that the silica particles prepared in Example 2 contained silica and iron oxide components. At this time, the carbon component shown in the EDS data is thought to be derived from the carbon tape used for fixing the sample.

Referring to FIG. 3D , in the FT-IR spectrum of the silica particles prepared in Example 2, an absorption peak that appears to be derived from iron oxide was observed compared to the FT-IR spectrum of pure silica.

On the other hand, referring to FIG. 4 , it was confirmed that the diffraction peak was strengthened in Example 2, in which the volume ratio of the aqueous silicic acid solution and the iron oxide solution was 5:1, compared to Example 1 in which the volume ratio of the aqueous silicic acid solution and the iron oxide solution was 10:1. That is, it can be seen that as the content of iron oxide contained in the silica particles increases, the diffraction peak becomes stronger, which seems to be due to the fact that silica is an amorphous material and iron oxide is a crystalline material.

Water treatment performance evaluation of silica particles

Adsorbent performance evaluation

The adsorption performance evaluation of the silica particles prepared in Examples 1 to 4 was performed as follows.

Silica particles were added at a concentration of 0.001 g/ml to the treatment solution containing methylene blue, which is the target to be removed, and the decrease in the concentration of methylene blue with the lapse of adsorption time was compared with the initial concentration of methylene blue. The concentration of methylene blue was measured through ultraviolet-visible absorption spectrum equipment (OPTIZEN, POP), and the value of C/C ₀ , which is the ratio of the concentration ( C ) according to the adsorption time to the initial concentration ( C _{0 ) of methylene blue.} shown in the graph.

Figure 10a is a graph showing the concentration of methylene blue according to the adsorption time of the silica particles prepared according to Example 1 of the present invention, Figure 10b is methylene according to the adsorption time of the silica particles prepared according to Example 2 of the present invention It is a graph showing the concentration of blue, Figure 10c is a graph showing the concentration of methylene blue according to the adsorption time of the silica particles prepared according to Example 3 of the present invention, Figure 10d is a graph prepared according to Example 4 of the present invention It is a graph showing the concentration of methylene blue according to the adsorption time of silica particles.

Specifically, in FIGS. 10a and 10b, respectively, when the initial concentration of methylene blue is 0.00001 g/ml and when the initial concentration of methylene blue is 0.000005 g/ml, the silica particles prepared in Examples 1 and 2 are shown in FIGS. Adsorption performance was shown.

In FIG. 10c, when the initial concentration of methylene blue is 0.00001 g/ml, when the initial concentration of methylene blue is 0.000005 g/ml, when the initial concentration of methylene blue is 0.0000025 g/ml, the silica prepared in Example 3 The adsorption performance of the particles was shown.

10c shows the adsorption performance of the silica particles prepared in Example 4 when the initial concentration of methylene blue is 0.000005 g/ml.

Referring to FIGS. 10A to 10D , it was confirmed that the silica particles prepared in Examples 1 to 4 of the present invention had excellent adsorption performance for methylene blue. In particular, it was confirmed that the silica particles prepared in Example 1 in which the volume ratio of the aqueous silicic acid solution and the iron oxide solution were 10:1 and the silica particles prepared in Example 2 in which the volume ratio of the aqueous silicic acid solution and the iron oxide solution was 5:1 were excellent.

Since the silica powder containing iron oxide prepared in the present invention has a negative surface charge under neutral pH conditions, it can be electrostatically bound to methylene blue molecules, which are cationic dyes. Through this electrostatic attraction, it is possible to adsorb and remove the methylene blue dye dissolved in water by using silica powder as an adsorbent.

Photocatalyst Performance Evaluation

The photocatalytic performance evaluation of the silica particles prepared in Example 5 was performed as follows.

Silica particles were added at a concentration of 0.0001 g/ml to a solution to be treated containing methylene blue to be removed, and the concentration of methylene blue over time of UV irradiation was compared with the initial concentration of methylene blue. After stirring the sample in a dark room for 30 minutes for photocatalytic decomposition, the change in the concentration of methylene blue according to the UV irradiation time was measured while irradiating UV light through an UV lamp.

In the silica powder containing titanium dioxide prepared in the present invention, a titanium dioxide component having photocatalytic properties is mixed. Therefore, when irradiated with ultraviolet rays, active radicals are formed from titanium dioxide, and organic substances such as methylene blue dissolved in water can be decomposed. Since the photocatalytic decomposition process occurs simultaneously with the adsorption process of the dye on the silica surface, the dye removal is facilitated. In addition, it can be expected that the organic dye can be removed even when the concentration of the silica powder is lowered compared to the case of using the adsorbent.

11a and 11b are graphs showing the concentration of methylene blue according to the UV irradiation time of the silica particles prepared according to Example 5 of the present invention. 11B is a semi-log plot of the data of FIG. 11A, and the rate constant of the methylene blue decomposition reaction can be estimated through the slope.

Since it was confirmed that the measured values of FIG. 11b are regressed through a straight line, it can be seen that the photocatalytic properties of the silica particles including titanium dioxide and iron oxide prepared in the present invention can be interpreted as a first-order reaction.

Table 1 below summarizes the rate constants of the decomposition reaction of methylene blue derived from FIG. 11b according to the concentration of methylene blue initially dissolved in water. It can be seen that the lower the concentration of methylene blue initially, the faster the rate of decomposition is due to the increase of the rate constant.

Initial concentration of methylene blue 0.000005 g/ml 0.00001 g/ml 0.00002 g/ml Rate constant of methylene blue decomposition reaction 0.0157 min ^-1 0.031 min ^-1 0.0049 min ^-1

11A and 11B , it was confirmed that the silica particles prepared in Example 5 of the present invention had excellent photocatalytic performance.

recovery of silica particles

The silica particles of Example 5, which completed the above-described photocatalytic performance evaluation, were recovered using a magnet.

12 is a photograph taken after the silica particles prepared according to Example 5 of the present invention were recovered using a magnet after the photocatalytic performance evaluation was completed. Referring to FIG. 12 , when the round magnet is fixed to the outside of the bottom of the beaker containing the water treatment solution, it can be seen that the silica particles are collected at the bottom of the beaker according to the shape of the magnet. Therefore, it was confirmed that the silica particles of the present invention possess magnetism and can be easily recovered through a magnet after water treatment is completed.

The above detailed description illustrates and describes the present invention. In addition, the foregoing is merely to indicate and describe preferred embodiments of the present invention, and as described above, the present invention can be used in various other combinations, modifications and environments, the scope of the concepts of the invention disclosed herein, and the writing Changes or modifications are possible within the scope equivalent to one disclosure and/or within the skill or knowledge in the art. Accordingly, the detailed description of the present invention is not intended to limit the present invention to the disclosed embodiments. In addition, the appended claims should be construed to include other embodiments as well.

Claims (9)

mixing an aqueous silicic acid solution and an iron oxide solution in a volume ratio of 1:1 to 10:1 to prepare a solution for forming magnetic silica;
forming an emulsion by emulsifying the solution for forming silica having the magnetic properties;
heating the emulsion to form a gel; and
Including; by heat-treating the gel to form silica particles containing iron oxide;
The silica particles have a spherical shape and a porous surface, and the method for producing a silica particle having magnetism in which the iron oxide nanoparticles are dispersed.
According to claim 1,
Preparing a silicic acid solution from a silica precursor solution, and mixing the silicic acid solution with water to prepare the silicic acid aqueous solution; Method for producing silica particles having magnetism further comprising.
3. The method of claim 2,
The step of preparing the aqueous solution of silicic acid,
A method for producing silica particles having magnetism by mixing the silicic acid solution and the water in a volume ratio of 1:1 to 1:10.
delete According to claim 1,
The step of preparing a solution for forming silica having the magnetic properties,
A method for producing silica particles having magnetism by additionally mixing a titanium dioxide solution with the mixture of the silicic acid aqueous solution and the iron oxide solution.
6. The method of claim 5,
The solution for forming silica having the magnetic properties,
A method for producing silica particles having magnetism in which the volume ratio of the aqueous solution of silicic acid to the titanium dioxide solution is 1:1 to 3:1.
6. The method of claim 5,
The solution for forming silica having the magnetic properties,
A method for producing silica particles having magnetism in which the volume ratio of the iron oxide solution and the titanium dioxide solution is 1:1 to 1:5.
According to claim 1,
The step of forming the gel is a method for producing silica particles having magnetism that is performed at a temperature of 85 ℃ or more and 95 ℃ or less.
According to claim 1,
The heat treatment step is a method for producing silica particles having magnetism is carried out at a temperature of 450 ℃ or more and 550 ℃ or less.

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