JPH10214710A - Magnetic silica gel and method for producing the same - Google Patents

Abstract

[PROBLEMS] To provide a magnetic silica gel having a shape, particle size, pore diameter, and strength physical properties, and a method for producing the same, which can be used as an adsorbent, an adsorption carrier, an extractant, an extraction carrier, a catalyst carrier, and the like. I will provide a. SOLUTION: The content of the magnetic substance is 5 to 50% by weight of the total amount, the average particle diameter is 1 to 200 μm, and the average pore diameter is 3 to 20.
0 nm, pore volume of 0.1-2.5 ml / g,
A magnetic silica gel having a BET specific surface area of 100 to 800 m ² / g and a production method in which a Si alkoxide polymer is produced from a Si alkoxide and a magnetic substance is supported on the polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has magnetism and strength that can be used as an adsorbent, an adsorption carrier, an extractant, an extraction carrier, a catalyst carrier, etc.
The present invention relates to a silica gel whose particle size and pore characteristics can be controlled and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, silica gel and the like are well known as an adsorbent and a solid phase carrier for adsorption. In the case of using these, a centrifugal separation method or filtration with a filter is used for their recovery. It had to be done and was not a convenient method. In addition, in the adsorption and extraction operations, it is necessary to separate the target adsorbate or extract from other substances, but conventional centrifugation, column separation,
In a technique such as an electrophoresis method, there is a problem that it takes a long time only for separation, and it is not a simple method.

[0003] Therefore, as a means for separating a target substance, a method of adding a ferromagnetic substance to a particle and applying a magnetic field to recover the target particle as described in JP-A-60-244251 has been proposed. there were. However, in this method, even when it is desired to carry out the operation in a state where the particles are uniformly dispersed in the adsorption, extraction, reaction operation, etc., the ferromagnetic material itself self-associates, and the state of the particles can be freely determined. It had the disadvantage that it could not be controlled.

In recent years, as a method of eliminating self-association of a ferromagnetic material itself, as described in Japanese Patent Application Laid-Open No. 61-181967,
A method using a superparamagnetic material as a magnetic material is disclosed. Further, as described in Japanese Patent Application Laid-Open No. 4-501957, it is disclosed that magnetic particles containing a superparamagnetic substance can be used as a solid phase for immobilizing a sample, and can be used for separation, analysis, and the like of proteins, cells, and DNA. . Further, Patent No. 255425
No. 0 discloses a reagent carrier having high mobility in which a superparamagnetic magnetically reactive substance is captured in a gel matrix. The superparamagnetic magnetic particles described in the above are ferromagnetic materials such as iron oxide formed into fine particles smaller than the size of a magnetic domain necessary for maintaining permanent magnetism and contained in the particles. It has the properties shown. Utilizing this property, it is a method in which an external magnetic field is not applied when dispersing, and an external magnetic field is applied when aggregating, so that particles in a solution are aggregated. However, even in these methods, it cannot be said that the magnetic particles are obtained by a method in which the physical properties of the magnetic particles are sufficiently controlled, and the physical properties of the magnetic particles are sufficiently controlled in accordance with various uses to produce optimal magnetic particles. A way to do that was desired.

As a method for obtaining magnetic silica gel, as described in JP-A-7-235407, a silica sol is obtained by a neutralization reaction of sodium silicate, a magnetic substance is added to the sol, and the gel is further gelled. There is a way. But,
In this method, a certain amount of the magnetic substance cannot be introduced due to the precipitation of the magnetic substance, and further, the physical properties of the magnetic particles cannot be controlled. In addition, even with a method of obtaining a magnetic gel by adding magnetic particles to sodium silicate and gelling the same, the desired amount of a magnetic substance cannot be contained, and the physical properties of the magnetic particles cannot be controlled. Had.

On the other hand, when such magnetic particles are used as a catalyst carrier, they have high reaction efficiency and can be used as a fixed bed, or they can be separated and recovered after the reaction or treatment. There has been a demand for a method for producing magnetic particles having high pressure resistance and high pressure resistance.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and the like, that is, to provide an adsorbent and a carrier for extraction, an extractant and a carrier for extraction, a catalyst carrier and the like. An object of the present invention is to provide a magnetic silica gel having a suitable shape, particle size, pore size, and strength properties, and a method for producing the same.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a certain amount of a magnetic substance has been added to silica gel to provide magnetism, and the average particle size and
Shapes such as average pore diameter, pore volume, BET specific surface area,
By controlling physical properties such as particle size and pore characteristics, it will be useful as various adsorption carriers, extraction carriers, and catalyst carriers.Furthermore, as a method of producing the same, a Si alkoxide polymer is brought into contact with a magnetic material to form a spheroid. , Then gel, wash,
It has been found that the composition can be easily manufactured by performing a drying treatment, and the present invention has been completed.

That is, according to the present invention, the content of the magnetic substance is 5 to 50% by weight of the total amount, the average particle diameter is 1 to 200 μm, the average pore diameter is 3 to 200 nm, and the pore volume is 0.1 to 2.5. Milliliter / g, BET specific surface area 100-800 m ²
/ G of magnetic silica gel and a method for producing the same.

Hereinafter, the present invention will be described in detail.

First, the magnetic silica gel of the present invention will be described.

The magnetic material used in the magnetic silica gel of the present invention is a material that exhibits so-called superparamagnetism that generates strong magnetism when given a magnetic force and loses the magnetism when the magnetic force is lost. Examples of those exhibiting such properties include spinel-type and plumbite-type ferrites and alloys containing iron, nickel, cobalt, or the like as a main component. Among these, a magnetic fluid obtained by suspending ultrafine particles of magnetite or ferrite in water or an organic solvent is preferably used.

Here, the magnetic fluid used in the present invention will be described in more detail. The term "magnetic fluid" refers to a magnetic fluid having a diameter of about 10 nm or less, such as magnetite or ferrite, suspended in water or an organic solvent. In the method for producing a magnetic silica gel of the present invention described below, which is a colloidal fluid, a surfactant may be added for stabilizing the magnetic fine particles in the magnetic fluid in a solvent.

This magnetic material is included in silica gel to obtain a silica gel having magnetism. The content of the magnetic material must be in the range of 5 to 50% by weight based on the total amount of the magnetic silica gel. is there. When the content of the magnetic material is less than 5% by weight, the magnetic properties of the obtained magnetic silica gel are not sufficient, so that the reaction efficiency,
If the amount exceeds 50% by weight, the shape of the magnetic silica gel cannot be spherical,
There is a problem in physical properties such that sufficient porosity cannot be imparted, and furthermore, it is difficult to chemically modify the surface of the obtained magnetic silica gel, which is not preferable.

The average particle size of the magnetic silica gel of the present invention is in the range of 1 to 200 μm. When the average particle size is less than 1 μm, there are problems that the particles are too small, so that it takes too much time for separation, and that a desired flow rate cannot be obtained when the catalyst is used in a fixed bed as a carrier for a catalyst. Therefore, when the thickness is more than 200 μm, there is a problem that the gel is broken on an actual surface of use and the shape cannot be maintained, which is not preferable.

The range of the average pore diameter of the magnetic silica gel of the present invention is from 3 to 200 nm. Average pore size is 3n
If it is less than m, the diameter is too small and the reaction efficiency as a carrier for adsorption, extraction, and catalyst is deteriorated. If it is more than 200 nm, the shape retention is deteriorated, which is not preferable.

The range of the pore volume of the magnetic silica gel of the present invention is 0.1 to 2.5 ml / g. When the pore volume is less than 0.1 ml / g, the performance as a carrier, particularly the reaction efficiency, is deteriorated, and when the pore volume exceeds 2.5 ml / g, the shape retention is deteriorated. Therefore, it is not preferable.

The range of the BET specific surface area of the magnetic silica gel of the present invention is 100 to 800 m ² / g. BE
Since T ratio surface area is of less than 100 m ² / g smaller surface area of the magnetic silica gel, performance as a carrier, which is the application surface, in particular the reaction efficiency is deteriorated, its shape retention when exceeding 800 m ² / g Is not preferred because it becomes worse.

Next, a method for producing the magnetic silica gel of the present invention will be described.

The starting material of the magnetic substance in the magnetic silica gel of the present invention is desirably a magnetic fluid, and its production method can be carried out by a known method. Can be manufactured.

A) Hydrolysis of Si alkoxide with acid to form S
i) a step of forming an alkoxide polymer b) a step of adding a magnetic substance to the alkoxide polymer c) a step of dispersing a mixed solution of the alkoxide polymer and the magnetic substance in water to form a spheroid and gelling with an alkali d) washing the gel with water and replacing the solvent with water Then, the drying step Here, as the Si alkoxide used in the production method of the present invention, in the production method described below, it can be used without particular limitation as long as it produces a polymer by hydrolysis, for example, Si (OCH ₃ ) ₄ , Si
_{(OC 2 H 5) 4,} Si (O-n-C 3 H 7) 4, Si (O-
_{i-C 3 H 7) 4} , Si (O-n-C 4 H 9) 4, Si (O-
i-C ₄ H ₉₎ can be given ₄ or the like. In the production method of the present invention, other metal alkoxides may be added in addition to the Si alkoxide.

First, the alkoxide of Si is partially hydrolyzed in an acidic solution so as not to gel. As the acidic solution, a mixed solution of an acid, water and an organic solvent is preferable. Examples of the acid used at this time include inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid, and organic acids such as acetic acid and formic acid. As the organic solvent, those which are uniformly mixed with an acid, water and a Si alkoxide are preferable, and alcohols such as methanol and ethanol are particularly preferable. The amount of water to be added is preferably an amount that partially hydrolyzes the Si alkoxide, that is, within 4 moles per mole of the Si alkoxide. As a condition of the hydrolysis reaction, the mixed solution may be stirred at a temperature of 10 to 80 ° C. for 30 minutes to 5 hours in order to uniformly hydrolyze the Si alkoxide.

After completion of the hydrolysis of the Si alkoxide, the Si alkoxide solution is polymerized. The polymerization may be carried out at a temperature in the range of 10 to 200 ° C. for 1 to 48 hours. After the reaction, the solvent or the alcohol produced by the reaction is distilled off to obtain a Si alkoxide polymer.
The polymerization degree of the Si alkoxide polymer can be controlled by the amount of water, the polymerization temperature, the polymerization time and the like. There is a correlation between the degree of polymerization and the viscosity of the Si alkoxide polymer,
The higher the degree of polymerization of the Si alkoxide polymer, the higher the viscosity. The degree of polymerization of the Si alkoxide polymer may be at least 10 centipoise in viscosity at room temperature, and may be such that gelation does not occur. For example, JIS-K-7117
It can be confirmed by measuring the viscosity at 25 ° C according to -1987. Furthermore, in order to uniformly disperse the magnetic material when it is added, the polymerization degree of the Si alkoxide polymer is preferably 20 to 1000 mPa · s (= centipoise) at 25 ° C. If the viscosity is in this range, a spherical gel can be obtained during gelation.

The obtained Si alkoxide polymer is diluted as it is or with an organic solvent. Examples of the organic solvent used for diluting the Si alkoxide polymer with an organic solvent include hydrocarbons such as cyclohexane and benzene, 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, 1-hexanol, Those which hardly dissolve in water, such as alcohols such as hexanol, are preferred. Further, the concentration of the Si alkoxide polymer when diluted with an organic solvent is preferably 20% by weight or more based on the total amount of the solution diluted to obtain a spherical gel.

Next, a magnetic substance is added to the Si alkoxide polymer. The magnetic substance used may be a suspension or a solution dispersed in water or an organic solvent. As the magnetic material, a magnetic fluid is preferably used from the viewpoint of dispersibility in the Si alkoxide polymer. As the magnetic fluid, a commercially available product or the like can be used as it is or after performing solvent substitution or the like.

Here, in dispersing the magnetic substance into the polymer, it is preferable to uniformly disperse the magnetic substance in a mixed solution of the Si alkoxide polymer and its diluting solvent. It is preferable to use a low-polarity organic solvent. As this organic solvent,
For example, hydrocarbons such as cyclohexane and benzene, 1-
Butanol, 2-butanol, 1-pentanol, 2-butanol
Examples include alcohols such as pentanol, 1-hexanol, and 2-hexanol.

Further, in order to disperse and stabilize the magnetic substance mixed with the solvent or the magnetic substance in the magnetic fluid, the surface of the magnetic substance or the vicinity of the surface is treated with a surfactant or the like. It is preferable to add. Further, when mixing the magnetic material with the Si alkoxide polymer, in order to uniformly disperse the magnetic material, the Si alkoxide polymer preferably has a low degree of polymerization, and in particular, the viscosity of the Si alkoxide polymer at 25 ° C. 20-200m
Preferably, the pressure is Pa · s.

As described above, by combining the selection of the magnetic substance, the degree of polymerization of the Si alkoxide polymer, and the dilution solvent of the Si alkoxide polymer, the magnetic substance can be uniformly dispersed in the Si alkoxide polymer.

Next, a mixed solution or a mixture of the Si alkoxide polymer or a mixed solution obtained by adding a diluting solvent to the Si alkoxide polymer and a magnetic material is dispersed in water with stirring to form a spheroid. here,
A dispersant such as a surfactant and polyvinyl alcohol may be added to water for dispersing the mixture.

After spheroidization, a basic substance is added to the above-mentioned mixed solution or mixture to gel. Examples of the basic substance used here include inorganic basic compounds such as ammonia, sodium hydroxide and potassium hydroxide, and organic basic compounds such as amines and urea. In order to completely hydrolyze the alkoxy group in the Si alkoxide polymer at the time of gelation, stirring may be performed at a pH of 8 to 11 and a temperature of 30 to 100 ° C. for 1 to 10 hours.

The formed gel is separated by filtration, centrifugation, etc., washed with water and dried. A known method can be used as a method of filtration and separation. The water used for washing may be any water that can be used normally, such as water or warm water.

Further, as for drying conditions, the gel shrinks and coagulates when the water inside the gel and the surface of the gel are directly evaporated, so that the gel is dried by any of the following three methods.

The first method is to replace the water in the gel with an organic solvent and then remove the organic solvent by heating. As the organic solvent used here, a solvent having a lower surface tension than water is preferable, and a solvent that dissolves in water at an arbitrary ratio is more preferable. Here, the solvent having a lower surface tension than water is defined as W of water.
Since the surface tension against air at 25 ° C. by the ilhelm method is 72 dyn / cm (= 10 ⁻³ Nm ⁻¹ ), a solvent having a surface tension smaller than this can be selected. The selection of the solvent is the same in the first method and the second method described below. The distillation of water and the solvent is usually performed at normal pressure, but may be performed under reduced pressure. Also,
In this method, when the aggregation of the gel is strong, the gel is dispersed again in water or an organic solvent, then replaced with an organic solvent, and the organic solvent is removed by heating, whereby the aggregation of the gel can be eliminated.

The second method is to replace the water in the gel with an organic solvent and then remove the organic solvent by heating. As the organic solvent used here, a solvent having a higher boiling point and a lower surface tension than water is preferable, and a solvent which dissolves in water at an arbitrary ratio is more preferable. For example, formamide, N, N-dimethylformamide, ethylene glycol, propylene glycol and the like can be mentioned. In the case of a solvent that does not dissolve in water at an arbitrary ratio, the solvent can be used by mixing with a solvent that dissolves in an arbitrary ratio with water and a substitution solvent. Examples of such a combination of solvents include a combination of a high-boiling alcohol such as 1-butanol, 1-pentanol, 2-pentanol, 1-hexanol, and 2-hexanol and a low-boiling alcohol such as methanol and ethanol. Can be

The third method is a method in which an organic solvent is added and heated, and water in the gel is distilled off together with the solvent.
As the organic solvent used here, a solvent having a higher boiling point and a lower surface tension than water is preferable, and a solvent azeotropic with water is more preferable. For example, alcohols such as 1-butanol, isobutyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, isoamyl alcohol, esters such as methyl butyrate and ethyl butyrate, cyclopentanone, 3
And ketones such as -heptanone and 4-heptanone. The distillation of water and the solvent is usually performed at normal pressure, but may be performed under reduced pressure.

Before or after drying the gel, the gel may be heated to 100 to 300 ° C. in an autoclave together with about the same volume of water as the gel and subjected to hydrothermal treatment for 1 to 24 hours. During this treatment, the pore distribution and pore volume can be controlled by changing the temperature, time, and pH of the liquid.

By the above method, the content of the magnetic substance is 5 to 50% by weight of the total amount, the average particle diameter is 1 to 200 μm, the average pore diameter is 3 to 200 nm, and the pore volume is 0.1 to 2.5 ml. / G and a magnetic silica gel of the present invention having a specific surface area of 100 to 800 m ² / g are obtained.

The magnetic silica gel of the present invention can be used as it is for adsorption, extraction, and reaction, and its surface is chemically modified to produce biologically-derived materials such as proteins such as antibodies and enzymes, peptides and nucleic acids. It can also be used as an immobilized carrier used in various measuring methods such as immunoassay and nucleic acid measurement, and separation means such as affinity chromatography.

[0039]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. In addition, each evaluation was implemented by the method shown below.

The magnetic hysteresis of the magnetic fluid used in the examples was measured using a vibrating sample magnetometer (VSM) (manufactured by Riken Denshi, Model: BHV-50). It was shown.

(1) Content of magnetic substance For Si, magnetic silica gel was decomposed with aqua regia,
It was treated with perchloric acid and measured by a gravimetric method. Fe (iron) was decomposed with nitric acid / hydrofluoric acid, treated with perchloric acid, and measured by ICP emission method.

(2) Average Particle Size A part of the magnetic silica gel was subjected to scanning electron microscope ISI-1
30 (manufactured by COULTER) and determined by an intercept method.

(3) Average Pore Size and Pore Volume The pores were measured using a pore sizer 9320 (manufactured by MICROMERITICS) in a pressure range of 0 to 207 MPa by a mercury intrusion method.

(4) BET Specific Surface Area BON specific surface area was measured by MONOSORB (manufactured by QUANTACHROME, USA) by the BET one-point method.

(5) Viscosity The viscosity at 25 ° C. was measured with a B-type viscometer (Model: BH, manufactured by Tokyo Keiki Co., Ltd.) in accordance with JIS-K-7118-1987.

(6) Surface Analysis of Gel Fe and Si on the surface were measured with an X-ray photoelectron spectrometer (ESCA5400MC, manufactured by Perkin-Elmer).
Was analyzed.

(7) Internal Analysis of Gel The distribution of the magnetic substance inside the magnetic silica gel was measured by the following method. That is, magnetic silica gel was embedded in an epoxy resin and cut with a microtome. After this, C (carbon) is deposited on the surface, and this is JCMA-
Using 733 (manufactured by JEOL Ltd.), first, scanning electron microscope (SEM) observation was performed, and further, Si and Fe surface analysis was performed by XMA.

Example 1 150.0 g of Si (OC ₂ H ₅ ) ₄ and ethanol 6
2.7 g of the mixed solution was stirred at 40 ° C. for 30 minutes. While stirring this mixed solution at 40 ° C., 14.9 g of a 1/100 N aqueous hydrochloric acid solution was added dropwise. After the solution was stirred for 1 hour, the mixture was stirred at 90 ° C. for 4 hours and further at 165 ° C. for 12 hours to remove distillate, thereby obtaining a Si alkoxide polymer. This operation was performed in a nitrogen atmosphere. When the viscosity of the obtained Si alkoxide polymer was measured by the method described above, the viscosity was 50 centipoise at room temperature. 70.0 g of the obtained Si alkoxide polymer was dissolved in 70.0 g of 1-pentanol. To this solution, 20 ml of a commercially available magnetic fluid (manufactured by Ferrotec Co., Ltd .: 35% by weight of magnetic substance, 10% by weight of surfactant, containing 1-butanol solution, based on the total amount) was added, and the homogeneous solution was added. Obtained. This solution was added to 560.0 g of a 5% aqueous solution of polyvinyl alcohol at 80 ° C. while stirring. After stirring for 30 minutes, 12.5 ml of a 5% aqueous NH ₄ OH solution was added, and the mixture was stirred at 80 ° C. for 3 hours. The resulting suspension is
The mixture was poured into 1000 ml of warm water at ℃, and the solid was collected by filtration and washed with warm water. After washing, the mixture was replaced with 2-propanol three times and dried under vacuum to obtain spherical magnetic silica gel. The Fe content of the obtained magnetic silica gel, the Si / Fe composition (A), and the surface Si /
Fe molar ratio (B), surface Si / Fe showing surface Si distribution
Molar ratio and Si / Fe composition ratio (B / A), average particle size, B
The ET specific surface area, the average pore diameter by the mercury intrusion method, the pore volume, and the like were measured by the methods described above, and the results are shown in Table 1.

[0049]

[Table 1]

Example 2 In the same manner as in Example 1, 1000 ml of 1-butanol was added to the gel which had been subjected to the water washing treatment.
After heating to 0 ° C and azeotropic distillation of water, 1-butanol was distilled off. The resulting powder was dried under vacuum to obtain spherical magnetic silica gel. The obtained magnetic silica gel was measured in the same manner as in the examples, and the results are shown in Table 1.

Example 3 In the same manner as in Example 1, the gel which had been subjected to the water washing treatment was replaced with N, N-dimethylformamide as a solvent, and vacuum-dried to obtain spherical magnetic silica gel. The obtained magnetic silica gel was measured in the same manner as in the examples, and the results are shown in Table 1.

Example 4 A spherical magnetic silica gel was obtained in the same manner as in Example 1 except that the amount of the 1 / 100N-hydrochloric acid aqueous solution was changed to 16.8 g. At this time, the viscosity of the obtained Si alkoxide polymer was measured by the method described above.
It was 50 centipoise. The obtained magnetic silica gel was measured in the same manner as in the examples, and the results are shown in Table 1.

Example 5 A spherical magnetic silica gel was obtained in the same manner as in Example 1 except that 30 g of 1-pentanol was used as a dilute solution of the Si alkoxide polymer. The obtained magnetic silica gel was measured in the same manner as in the examples, and the results are shown in Table 1.

Example 6 A spherical magnetic silica gel was obtained in the same manner as in Example 1 except that the amount of the magnetic fluid was changed to 10 ml. The obtained magnetic silica gel was measured in the same manner as in the examples, and the results are shown in Table 1.

Example 7 Spherical magnetic silica gel was obtained in the same manner as in Example 1 except that the amount of the magnetic fluid was changed to 30 ml. The obtained magnetic silica gel was measured in the same manner as in the examples, and the results are shown in Table 1.

Comparative Example 1 The procedure of Example 1 was repeated except that the amount of the 1 / 100N aqueous hydrochloric acid solution was changed to 12.0 g. At this time, when the viscosity of the obtained Si alkoxide polymer was measured by the method described above, the viscosity was 8 centipoise at room temperature. The obtained gel did not become spherical but was amorphous. The obtained magnetic silica gel was measured in the same manner as in the example except for the average pore diameter and the pore volume, and the results are shown in Table 1.

Comparative Example 2 The procedure of Example 1 was repeated except that ethanol was used as a solvent for diluting the Si alkoxide polymer. In this case, when the magnetic fluid was added, the magnetic substance in the magnetic fluid precipitated. The obtained magnetic silica gel was measured in the same manner as in the examples, and the results are shown in Table 1.

Comparative Example 3 The procedure of Example 1 was repeated except that a magnetic fluid containing 35% by weight of a magnetic substance, 0% by weight of a surfactant, and 1-butanol as a solvent was used. In this case, when the magnetic fluid was added, the magnetic substance in the magnetic fluid precipitated. The obtained magnetic silica gel was measured in the same manner as in the examples, and the results are shown in Table 1.

Comparative Example 4 The procedure of Example 1 was repeated except that the amount of 1-pentanol as a diluting solvent for the Si alkoxide polymer was changed to 280 g.
The obtained gel did not become spherical but was amorphous. The obtained magnetic silica gel was measured in the same manner as in the example except for the average pore diameter and the pore volume, and the results are shown in Table 1.

Comparative Example 5 A reaction vessel containing 25 g of a 15% by weight aqueous sulfuric acid solution was placed in a 20
C. and stirred. In this reaction vessel, while stirring,
An aqueous solution of sodium silicate having an iO ₂ concentration of 12% by weight
1 g was added to obtain silicic acid. Further, 22 ml of a commercially available magnetic fluid (manufactured by Ferrotech Co., Ltd .: 35% by weight of magnetic substance, 10% by weight of surfactant, containing 1-butanol solution, based on the total amount) was added to this solution, and 1 The mixture was allowed to react for a period of time to form a gel, and the temperature was further raised to 80 ° C., and the mixture was reacted for 2 hours to complete the gelation. After washing with warm water and drying, a magnetic gel was obtained. At this time, when the magnetic fluid was added, the magnetic substance aggregated and precipitated, and was not dispersed in the silica gel. In addition, the gel was not spherical, but was amorphous. The obtained magnetic silica gel was measured in the same manner as in the example except for the average pore diameter and the pore volume, and the results are shown in Table 1.

Comparative Example 6 Gelation was completed in the same manner as in Comparative Example 5, washed with warm water, dispersed in water, wet-pulverized, and then cooled to an inlet temperature of 1%.
Spray-drying was performed with a disk-type spray dryer set at 00 ° C and an outlet temperature of 60 ° C to obtain magnetic silica gel. At this time, when the magnetic fluid was added, the magnetic substance aggregated and precipitated, and was not dispersed in the silica gel. The obtained magnetic silica gel was measured in the same manner as in the examples, and the results are shown in Table 1.

[0062]

The magnetic silica gel of the present invention is spherical,
It contains a sufficient amount of magnetic material inside, has a large pore volume, and it is clear that its strength is also large, so it can be used as an adsorbent, an adsorption carrier, an extractant, an extraction carrier, a catalyst carrier. It can be suitably used. Further, according to the production method of the present invention, it is possible to easily produce magnetic silica gel having pore characteristics according to various uses.

Claims (9)

[Claims] 1. A silica gel containing a magnetic substance, wherein the content of the magnetic substance is 5 to 50% by weight of the total amount and the average particle size is 1 to 20%.
0 μm, average pore diameter of 3 to 200 nm, pore volume of 0.
1 to 2.5 ml / g, BET specific surface area is 100
A magnetic silica gel characterized by having a molecular weight of ８００800 m ² / g. 2. The magnetic silica gel according to claim 1, wherein the magnetic material has a superparamagnetic structure. 3. The magnetic silica gel according to claim 1, wherein the magnetic silica gel is spherical. 4. The magnetic substance is present inside a magnetic silica gel,
4. The magnetic silica gel according to claim 1, wherein the surface has a silica layer structure. 5. The magnetic silica gel according to claim 4, wherein the magnetic substance is present in a state of being uniformly dispersed inside the silica gel. 6. The method for producing magnetic silica gel according to claim 1, wherein the production process comprises the following steps. a) a step of hydrolyzing a Si alkoxide with an acid to form a Si alkoxide polymer b) a step of adding a magnetic substance to the alkoxide polymer c) a mixture of the alkoxide polymer and the magnetic substance is brought into contact with water to form a spheroid, and further contacted with an alkali D) a step of washing the gel, replacing the solvent, and drying the gel 7. A method for producing a magnetic silica gel according to claim 6, wherein in step a) of the method for producing a magnetic silica gel according to claim 6, the viscosity of the Si alkoxide polymer is 20 to 1000 mPa · s at 25 ° C. 8. A method for producing a magnetic silica gel according to claim 6 or 7, wherein in step b) of the method for producing a magnetic silica gel according to claim 6 or 7, a magnetic fluid is used as a raw material of the magnetic substance. 9. The method according to claim 6, wherein in the step d) of the method for producing a magnetic silica gel, the treatment comprises replacing water in the gel with an organic solvent having a lower surface tension than water. A method for producing a magnetic silica gel.