WO2017209489A1 - Method for producing magnetic mesoporous silica by using sodium borohydride - Google Patents

Abstract

The present invention relates to a method for producing magnetic mesoporous silica. More specifically, the present invention relates to magnetic mesoporous silica having uniform pore distribution and excellent magnetism, the silica obtained by reacting mesoporous silica, having transition metal ions deposited therein, with a reducing agent at a specific temperature.

Description

Method for producing magnetic mesoporous silica using sodium borohydride

The present invention relates to a method for producing magnetic mesoporous silica. More specifically, the present invention relates to magnetic mesoporous silica having a uniform pore distribution and excellent magnetism, including reacting mesoporous silica carrying transition metal ions with a reducing agent at a specific temperature.

Magnetic nanoparticles are ferromagnetic particles and generally have a size of about 10 nm. Magnetic nanoparticles are widely used in the separation process of biological or chemical substances using magnetic, and have been typically used to diagnose diseases with NMR (nuclear magnetic resonance) increasing reagents and to treat diseases with drug carriers. In addition, magnetic nanocrystals with supermagnetism may be used for magnetothermal treatment of diseases such as tumors. Recently, the functional material is immobilized and used in separation processes such as DNA and proteome. Magnetic nanoparticles have the advantage that functional reuse is possible by immobilizing materials such as enzymes, biological catalysts, as well as increasing efficiency according to time savings. However, there are problems in efficiency reduction due to problems such as aggregation of magnetic nanoparticles and low surface reactivity, and unstable bonding between magnetic nanoparticle surfaces and surface modifying materials in processing a large amount or reducing the time of separation process.

Meanwhile, as a method for imparting magnetism to existing mesoporous silica, magnetic nanoparticles such as metal or iron oxide have been implanted into mesoporous silica. In this method, however, it is difficult for the magnetic nanoparticles having magnetic properties to be uniformly distributed in the well-aligned pores of the mesoporous silica. As a result, the magnetic nanoparticles are present in the pores to remove pores, thereby reducing the surface area and susceptibility. Let's go. In order to solve this problem, some experiments have suggested a method of mixing magnetic nanoparticles in the wall portion of mesoporous silica, but the magnetic nanoparticles that can be applied thereto are limited. Another method is hard-templating, in which magnetic nanoparticles are deposited after template deposition. And nano-casting method is applied in many ways to make metal oxide which is difficult to make by the conventional method. However, this treatment has a lower magnetization than when using pure metal.

 Recently, in order to compensate for such disadvantages, there is a method of reducing hydrogen to a high temperature. In the case of the manufacturing method of the high temperature hydrogenation method, a simple method of giving magnetism by reducing the temperature through a high temperature above 300 ° C. in a hydrogen atmosphere and through high temperature hydrogenation It has the advantage of being able to make mesoporous silica with a high magnetizing power without causing the collapse of pores with a metal material. However, this method requires a high temperature while maintaining a hydrogen atmosphere for a long time, and over-use without controlling the amount of hydrogen decreases the cost and efficiency accordingly, and also needs to maintain a hydrogen atmosphere at a high temperature. There are many problems and risks in the manufacturing process.

Prior literature

1. International Patent Publication WO2014-142378

2. Korean patent application KR2011-0035414

3. Korean patent application KR2012-0063635

The inventors of the present invention, while searching for a method for supplementing the problems of the magnetic nanoparticles, when reacting with mesoporous silica and transition metal ions that can control the size of the pores and easy to functionalize the surface and then reduced to sodium borohydride The present invention has been completed by confirming that magnetic mesoporous silica having a uniform pore distribution can be efficiently produced in a short time. In addition, the present inventors have confirmed that the pore distribution of the magnetic mesoporous silica can be controlled by controlling the temperature in the reduction step using sodium borohydride, and completed the present invention.

An object of the present invention is to provide a magnetic mesoporous silica.

As used herein, the term "mesoporous silica" refers to a porous material having a structure in which mesopores of uniform size are regularly arranged and having uniform pores as one of mesoporous molecular sieves, The mesoporous material has pores of 2 nm to 50 nm.

As used herein, the term "reducing agent" refers to a substance having a high property of reducing other substances as it is oxidized.

According to one embodiment,

(a) supporting transition metal ions on mesoporous silica; And

(b) A method of producing magnetic mesoporous silica, comprising reacting the mesoporous silica carrying the transition metal ion with a reducing agent at a temperature of 40 ℃ to 65 ℃.

In the method for producing magnetic mesoporous silica according to the present invention, the reducing agent is lithium aluminum hydride (LiAlH ₄ ), hydrazine (N ₂ H ₄ H ₂ O), sodium borohydride (NaBH ₄ ), sodium chloride (NaCl ), it may be selected from sodium hydroxide (NaOH), aqueous ammonia (NH ₄ OH), potassium bromide (KBr), and combinations thereof. Preferably, the reducing agent may be sodium borohydride (NaBH ₄ ).

In the method for producing magnetic mesoporous silica according to the present invention, the method may further comprise (c) vacuum drying at room temperature after washing the mesoporous silica on which the transition metal ion is supported with alcohol.

In the method for producing magnetic mesoporous silica according to the present invention, the transition metal ion may be selected from the group consisting of Co, Fe, Ni, Mn, and combinations thereof.

In the method for producing magnetic mesoporous silica according to the present invention, the mesoporous silica may be prepared by hydrothermal synthesis. The hydrothermal synthesis method is:

a) mixing the surfactant with a solvent comprising water and an acid;

b) adding a silica precursor to the mixed solution; And

c) aging, drying and calcining the solution mixed with the silica precursor. The surfactant is a carboxylate, sulfonate, sulfate ester salt, phosphate ester salt, phosphonate salt, amine salt, quaternary ammonium salt, phosphonium salt, sulfonium salt, fatty acid monoglycerine ester, fatty acid polyglycol ester, fatty acid sorbitan It may be any one or more selected from the group consisting of esters, fatty acid sucrose esters, fatty acid alkanolamides, polyethylene glycol condensed nonionic surfactants, polyethylene glycol-polypropylene glycol copolymers, but is not limited thereto. The silica precursor may be tetraethylorthosilicate (TEOS), tetramethoxysilane (TMOS), or silicon tetrachloride, but is not limited thereto.

According to another embodiment,

Disclosed is a magnetic mesoporous silica prepared by the method for producing magnetic mesoporous silica according to the present invention. The magnetic mesoporous silica may have a uniform pore distribution and excellent magnetic properties.

The method for producing magnetic mesoporous silica according to the present invention is efficient in a short time when the mesoporous silica and transition metal ions, which can control the pore size and are easy to functionalize the surface, are reacted and reduced with sodium borohydride. Magnetic mesoporous silica having a uniform pore distribution can be produced. In addition, the pore distribution of the magnetic mesoporous silica can be easily adjusted by controlling the temperature in the reduction step using sodium borohydride.

Figure 1 shows the results of the BET analysis of mesoporous before reduction according to Experimental Example 1.

Figure 2 shows the results of the BET analysis of the reduced magnetic mesoporous silica at room temperature according to Experimental Example 1.

Figure 3 shows the results of the BET analysis of the magnetic mesoporous silica reduced at 50 ℃ in Experimental Example 1.

Figure 4 shows the results of the BET analysis of the reduced magnetic mesoporous silica at 75 ℃ in Experimental Example 1.

5 is a photograph showing the magnetism of the magnetic mesoporous silica prepared according to the embodiment of the present invention.

6 shows the results of XRD analysis according to Experimental Example 2.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention in more detail, it will be apparent to those skilled in the art that the scope of the present invention is not limited to these examples.

<Example>

Example 1. Preparation of magnetic mesoporous silica using sodium borohydride

In order to synthesize mesoporous silica, nanoporous silica (MS) was first prepared. The nanoporous silica was prepared by mixing Pluronic P123, 2M HCl and secondary distilled water in a weight ratio of 2:60:15. The mixed solution became a transparent solution with stirring. After stirring for 24 hours at 40 ℃ using a constant temperature bath, 8.5 g of tetraethyl ortho silica (TEOS) was added and stirred for 8 hours. After stirring, the solution was administered to a steel press and placed in an oven at 120 ° C. for 8 hours. After aging, the solution was cooled to room temperature, washed with water, filtered and dried at room temperature to obtain a powder. The dried powder was calcined at 550 ° C. for 6 hours to produce homogeneous mesoporous silica.

FeCl _{2 ·} H ₂ O (Iron (II) chloride tetrahydrate) was dissolved in distilled water to prepare 250 mL of an aqueous solution of iron precursor of 3 M, and 5 g of homogeneous mesoporous silica on the solid powder prepared above was mixed with the iron precursor solution. After stirring for an hour, the iron precursor was supported on mesoporous silica. Then, the mesoporous silica loaded with iron precursor was filtered and stored at -70 ° C for 1 hour and then vacuum dried at room temperature for 12 hours. 1 g of the dried sample and 30 mL of secondary distilled water are placed in a three neck flask, and the temperature is maintained at 50 ° C. 100 mL of 1M boron hydride (NaBH ₄ ) is made and used as a dropping funnel every second. Dropped. At this time, in order to confirm the pore state and the supported state of the iron precursor according to the temperature, the reduction reaction by the sodium borohydride was performed at room temperature, 50 ℃ and 75 ℃, respectively. The state was maintained for 6 hours, washed with ethanol, and then vacuum dried at room temperature for 12 hours.

Experimental Example

Experimental Example 1.BET (Bruner-Emmet-Teller) analysis and magnetic confirmation

BET analysis was performed on the magnetic mesoporous silica prepared in Example 1 above. The device used for the analysis was Quantachrome Nova e-4000 Bruner-Emmet-Teller (Surface area range: 0.01-2,000 m ² / g; Adsorption and desorption isotherm; Pore diameter range: 3.5-500 nm). The results are shown in FIGS. 1-4. In addition, after confirming the magnetism close to the magnet to the mesoporous silica, the results are shown in FIG.

As can be seen from Figure 1-5, it was confirmed that the mesoporous silica before the reduction has a hysteresis phenomenon in which the adsorption line and the desorption line have a different form, it was confirmed that the mesoporous state, even when reduced at room temperature as before The mesoporous pores were shown in the form, but when they were reduced at room temperature, no magnetism was present. The result of hysteresis, which shows the form of pores when reduced at 50 ℃, was different, but the difference between the adsorption line and the desorption line indicates that the pores exist, and the magnetic body was well supported when the magnets were attached. This was confirmed. When reduced at 75 ° C., the pores had almost no uniform pore morphology, and even when the result of reacting with the magnet, it was confirmed that the pores were present in the form of Fe without pores.

Experimental Example 2 XRD Analysis

XRD analysis was performed on the magnetic mesoporous silica prepared in Example 1 using Rigaku 2311-B (at room temperature to 1400 ° C. in vacuum (10-3 Torr); heating element in He gas: Pt wire; thermocouple: R-type). The results are shown in FIG. 6.

As can be seen from Figure 6, before the reduction can be seen that the typical 2θ = 22 ° peak of mesoporous, but the peak of iron (Fe) 2θ = 11 ° was hardly confirmed, even when reduced at room temperature No peak was observed. On the other hand, when reduced at 50 ° C., 2θ = 11 °, which is a peak of iron (Fe), appeared, and 2θ = 22 °, which is a peak of silica, was also observed. When reduced at 75 ° C., the peak of 2θ = 22 ° of silica did not appear.

Specific structural to functional descriptions are merely illustrated for the purpose of describing the embodiments of the present invention, and the embodiments of the present invention may be embodied in various forms and include all modifications and equivalents included in the spirit and scope of the present invention. It is to be understood to include to substitutes.

The method for producing magnetic mesoporous silica according to the present invention is efficient in a short time when the mesoporous silica and transition metal ions, which can control the pore size and are easy to functionalize the surface, are reacted and reduced with sodium borohydride. Magnetic mesoporous silica having a uniform pore distribution can be produced.

Claims (6)

1. (a) supporting transition metal ions on mesoporous silica; And

   (b) reacting the mesoporous silica on which the transition metal ion is supported with a reducing agent at a temperature of 40 ° C. to 65 ° C., wherein the mesoporous silica is prepared.
2. The method of claim 1,

   The reducing agent is lithium aluminum hydride (LiAlH ₄ ), hydrazine (N ₂ H ₄ H ₂ O), sodium borohydride (NaBH ₄ ), sodium chloride (NaCl), sodium hydroxide (NaOH), ammonia water (NH ₄ OH), potassium bromide (KBr), and a combination thereof, the method of producing magnetic mesoporous silica.
3. The method of claim 1,

   (C) the method of producing a magnetic mesoporous silica further comprising the step of vacuum drying at room temperature after washing the mesoporous silica carrying the transition metal with alcohol.
4. The method of claim 1,

   The transition metal ion is selected from the group consisting of Co, Fe, Ni, Mn, and combinations thereof, a method for producing magnetic mesoporous silica.
5. The method of claim 1,

   The mesoporous silica is prepared by hydrothermal synthesis method, a method for producing magnetic mesoporous silica.
6. The method of claim 5,

   The hydrothermal synthesis method,

   a) mixing the surfactant with a solvent comprising water and an acid;

   b) adding a silica precursor to the mixed solution; And

   c) aging, drying and calcining the solution in which the silica precursor is mixed, the method of producing magnetic mesoporous silica.

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