JP2013209532A - Composite material of cyclodextrin and porous silica particle, and its production method, metal extractor, cesium extractor and gas adsorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite material of cyclodextrin and a porous silica particle useful for extraction of a metal or the like.SOLUTION: This composite material includes a polymer of cyclodextrin and a porous silica particle containing 3.0 mass% or more AlO, and a plurality of pores, where the polymer exists at least any of an outer surface of the porous silica particle and within the pore.

Description

  The present invention relates to a composite material of cyclodextrin and porous silica particles useful for extraction of metals from wastes and the like in the environment, a method for producing the same, a metal extractant using the composite material, and a cesium extractant. And a gas adsorbent.

  Cobalt (Co), titanium (Ti), nickel (Ni), vanadium (V), chromium (Cr), manganese (Mn), zinc (Zn), yttrium (Y), zirconium (Zr), hafnium (Hf), Niobium (Nb), cadmium (Cd), lanthanum (La), cerium (Ce), neodymium (Nd), europium (Eu), terbium (Tb), mercury (Hg), uranium (U), platinum (Pt), Metals such as palladium (Pd), rhodium (Rh), ruthenium (Ru), iridium (Ir), osmium (Os), barium (Ba), aluminum (Al), etc. It is a metal included in 31 ore types defined by the Rare Metal Countermeasures Subcommittee definition. These metals are indispensable for our daily lives, and are used in many products including current precision equipment such as automobile catalysts, fuel cells, and super-strong magnets.

  However, Japan currently relies on imports for most of these metals. For example, palladium and platinum are metals used as precision instrument materials and dental materials, and zirconium is a metal used as piezoelectric elements and capacitors. Palladium, platinum, and zirconium are one of the metals with the least amount in the earth's crust, and their prices are rising in recent years due to competition for resources by countries. For this reason, from the viewpoint of stable supply of resources and environmental protection, a method of recycling palladium, platinum, and zirconium has been proposed.

  On the other hand, radioactive substances such as radioactive cesium exist in the environment. It has been reported that exposure to the radioactive material has a large effect on the human body and there is a risk of generating cancer even when exposed to low doses. In addition, cesium is similar to potassium, so it is easy to concentrate in muscles, and it has been reported that it is concentrated 100 times or more with sea bass, skipjack, yellowtail and the like.

Therefore, in order to recover or remove the metal, a material capable of extracting the metal is desired.
Cyclodextrin is known as a material having an extraction ability for substances. The cyclodextrin is a substance in which a plurality of glucoses are continuously linked. The cyclodextrin has a space inside the molecule, and an organic compound or an inorganic compound enters the space to form an inclusion compound, whereby a substance can be extracted.

  As a technique using the cyclodextrin as an extractant, for example, a cyclodextrin composite material in which cyclodextrin is crosslinked with an epoxy compound in the presence of an inorganic powder has been proposed (see, for example, Patent Document 1). However, although the proposed technique is effective for extracting or removing environmental hormones and the like, there is a problem that sufficient effects cannot be obtained in the extraction of the metal.

  Further, a cyclodextrin composite material having an aspect ratio of 2 or more in which cyclodextrin is crosslinked with an epoxy compound in the presence of amorphous silicic acid or the like has been proposed (for example, see Patent Document 2). However, even this proposed technique has a problem that a sufficient effect cannot be obtained in the extraction of the metal. In one example of the proposed technique, amorphous or silicic acid is used instead of colorless or white, in which cyclodextrin is crosslinked with an epoxy compound in the presence of a supernatant of a solution obtained by placing diatomaceous earth in an aqueous sodium hydroxide solution. Although a cyclodextrin composite material is used, even this composite material cannot provide a sufficient effect in extracting the metal.

  Furthermore, not only metal extraction but also a material that exhibits extraction ability and adsorption ability for various substances such as gas adsorption is desired.

  Therefore, it is currently required to provide a composite material of cyclodextrin and porous silica particles useful for metal extraction and the like, a method for producing the same, a metal extractant, a cesium extractant, and a gas adsorbent. is there.

Japanese Patent No. 4225731 JP 2011-213743 A

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, an object of the present invention is to provide a composite material of cyclodextrin and porous silica particles, a method for producing the same, a metal extractant, a cesium extractant, and a gas adsorbent, which are useful for metal extraction and the like. To do.

Means for solving the problems are as follows. That is,
<1> a polymer of cyclodextrin;
Containing 3.0 mass% or more of Al ₂ O ₃ and porous silica particles having a plurality of pores,
The composite material is characterized in that the polymer is present on at least one of the outer surface of the porous silica particles and the pores.
<2> The composite material according to <1>, wherein the porous silica particles are diatomaceous earth.
<3> The composite material according to any one of <1> to <2>, wherein the polymer of cyclodextrin is obtained by polymerizing cyclodextrin and an epoxy compound.
<4> The composite material according to <3>, wherein the epoxy compound contains an epihalohydrin.
<5> The composite material according to any one of <1> to <4>, wherein at least part of the outer surface of the porous silica particles is coated with a cyclodextrin polymer.
<6> A metal extractant comprising the composite material according to any one of <1> to <5>.
<7> A cesium extractant containing the composite material according to any one of <1> to <5>.
<8> A gas adsorbent comprising the composite material according to any one of <1> to <5>.
<9> An addition step of adding cyclodextrin and porous silica particles containing 3.0% by mass or more of Al ₂ O ₃ and having a plurality of pores to the alkaline aqueous solution;
Subsequent to the adding step, a method for producing a composite material comprising a polymerization step of adding an epoxy compound to the alkaline aqueous solution and polymerizing the cyclodextrin and the epoxy compound.
<10> The method for producing a composite material according to <9>, wherein the epoxy compound contains an epihalohydrin.
<11> The method for producing a composite material according to any one of <9> to <10>, wherein the porous silica particles are diatomaceous earth.
<12> The above <9> to <11>, wherein the mass ratio of the cyclodextrin to the porous silica particles added to the alkaline aqueous solution in the addition step (porous silica particles / cyclodextrin) is 0.5 to 5. It is the manufacturing method of the composite material in any one.

  According to the present invention, the above conventional problems can be solved and useful for metal extraction and the like, a composite material of cyclodextrin and porous silica particles, and a production method thereof, a metal extractant, a cesium extractant, As well as a gas adsorbent.

1 is a graph showing the particle size distribution of the composite material 1 synthesized in Example 1. FIG. FIG. 2 is a SEM (scanning electron microscope) photograph of the composite material 1 obtained in Example 1. FIG. 3 is another SEM photograph of the composite material 1 obtained in Example 1. 4 is another SEM photograph of the composite material 1 obtained in Example 1. FIG. FIG. 5 is another SEM photograph of the composite material 1 obtained in Example 1. 6 is another SEM photograph of the composite material 1 obtained in Example 1. FIG. FIG. 7 is an SEM photograph of the composite material 2 obtained in Example 2. FIG. 8 is another SEM photograph of the composite material 2 obtained in Example 2. FIG. 9 is another SEM photograph of the composite material 2 obtained in Example 2. FIG. 10 is an SEM photograph of the composite material 3 obtained in Example 3. FIG. 11 is another SEM photograph of the composite material 3 obtained in Example 3. 12 is another SEM photograph of the composite material 3 obtained in Example 3. FIG. FIG. 13 is another SEM photograph of the composite material 3 obtained in Example 3. 14 is another SEM photograph of the composite material 3 obtained in Example 3. FIG. FIG. 15 is a SEM photograph of the composite material 5 obtained in Example 5. FIG. 16 is another SEM photograph of the composite material 5 obtained in Example 5. FIG. 17 is another SEM photograph of the composite material 5 obtained in Example 5. 18 is another SEM photograph of the composite material 5 obtained in Example 5. FIG. FIG. 19 is another SEM photograph of the composite material 5 obtained in Example 5. FIG. 20 is an SEM photograph of the composite material 6 obtained in Comparative Example 1. FIG. 21 is another SEM photograph of the composite material 6 obtained in Comparative Example 1. 22 is another SEM photograph of the composite material 6 obtained in Comparative Example 1. FIG. FIG. 23 is a diagram of a cesium extraction test result. FIG. 24 is a diagram of the metal extraction test results. FIG. 25 is a diagram of a metal extraction test result. FIG. 26 is a methanol adsorption isotherm of the composite material 1 obtained in Example 1.

(Composite material)
The composite material of the present invention contains at least a cyclodextrin polymer and porous silica particles, and further contains other components as necessary.
In the composite material, the polymer is present on at least one of the outer surface of the porous silica particles and the pores.
The composite material by the porous silica particles containing Al ₂ O ₃ of more than 3.0 mass%, excellent metal extraction capacity.

<Polycyclodextrin polymer>
The cyclodextrin polymer (hereinafter sometimes abbreviated as “polymer”) is obtained by polymerizing cyclodextrin.
The polymer may be a homopolymer only of the cyclodextrin or a copolymer obtained by polymerizing the cyclodextrin and another compound.
The polymer is preferably obtained by polymerizing the cyclodextrin and an epoxy compound.
If the said polymer has two or more structural units derived from the said cyclodextrin, there will be no restriction | limiting in particular, According to the objective, it can select suitably.

  A method for discriminating between the polymer and the cyclodextrin is not particularly limited and may be appropriately selected depending on the intended purpose. For example, mass spectrometry, infrared spectroscopy, ultraviolet-visible spectroscopy, nuclear magnetic resonance Examples thereof include a structural analysis method such as spectroscopy, a gel permeation chromatography (GPC) method, a method of discriminating by comparing the solubility of the cyclodextrin and the solubility of the polymer, and the like.

<< cyclodextrin >>
The cyclodextrin is a compound in which a D-glucose unit is cyclically bonded with an α-1,4-glucoside bond and a derivative thereof.
Examples of the cyclodextrin include α-cyclodextrin having 6 D-glucose units, 7 β-cyclodextrin, and 8 γ-cyclodextrin.
The cyclodextrin can be produced, for example, by allowing an enzyme such as cyclodextrin glucanotransferase to act on starch and / or a hydrolyzate of starch.
The derivative in the cyclodextrin refers to a cyclodextrin in which a substituent is partially introduced. Examples of the derivatives include branched-chain cyclodextrins, methylated cyclodextrins, hydroxyalkylated cyclodextrins, alkylsulfonated cyclodextrins obtained by adding glucose, maltose, maltotriose, etc. to the 6-position of glucose constituting cyclodextrins. Is mentioned.

<< Epoxy compound >>
The epoxy compound is not particularly limited as long as it is a compound having an epoxy group, and can be appropriately selected according to the purpose. For example, a monoepoxy compound having one epoxy group, a diepoxy having two epoxy groups Examples thereof include a compound and a triepoxy compound having three epoxy groups.
Examples of the monoepoxy compound include epihalohydrin.
Examples of the diepoxy compound include a diglycidyl ether compound.
Examples of the epihalohydrin include epichlorohydrin and epibromohydrin.
Examples of the diglycidyl ether compound include ethylene glycol diglycidyl ether and butanediol diglycidyl ether.
Among these, a monoepoxy compound is preferable, an epihalohydrin is more preferable, and an epichlorohydrin is particularly preferable because it can easily react under alkaline conditions and is inexpensive.

<< Polymerization >>
There is no restriction | limiting in particular as the said polymerization method, Although it can select suitably according to the objective, The method of superposing | polymerizing the said cyclodextrin and the said epoxy compound in aqueous alkali solution is preferable.
There is no restriction | limiting in particular as said alkaline aqueous solution, According to the objective, it can select suitably, For example, sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, etc. are mentioned.
There is no restriction | limiting in particular as reaction temperature in the said superposition | polymerization, Although it can select suitably according to the objective, 60 to 100 degreeC is preferable, 70 to 90 degreeC is more preferable, and 75 to 85 degreeC is especially preferable. .
There is no restriction | limiting in particular as reaction time of the said polymerization, Although it can select suitably according to the objective, 1 to 10 hours are preferable, 3 to 9 hours are more preferable, and 5 to 7 hours are especially preferable. .
The polymerization is preferably performed in a state where the porous silica particles are mixed with the alkaline aqueous solution.

<Porous silica particles>
The porous silica particle is not particularly limited as long as it is a silica particle containing 3.0% by mass or more of Al ₂ O ₃ and having a plurality of pores, and can be appropriately selected according to the purpose. Diatomaceous earth is preferable because it is excellent in metal extraction ability.
The diatomaceous earth is a deposit of diatom shells mainly composed of amorphous silica, where diatoms are deposited on the bottom of the sea or lake, protoplasms and other organic substances in the body decompose over a long period of time. .

Whether or not the silica particles have a plurality of pores, that is, whether they are porous silica particles can be confirmed by, for example, morphological observation using SEM photographs. For example, in SEM photograph observation, when dents such as a plurality of burrows are observed on the surface of the silica particles, the silica particles are porous silica particles. Other methods include, for example, a method of confirming the porous state by adsorbing an inert gas.
Further, when the silica particles have a plurality of pores, the bulk density is small (light) with respect to the true specific gravity. For example, a particle having a bulk density of 0.60 g / cm ³ or less is referred to as a porous silica particle. it can. The said bulk density (cake bulk density) can be calculated | required by filling the powder in a fixed volume container and measuring the weight, for example.

The content of SiO ₂ in the porous silica particles is not particularly limited and may be appropriately selected depending on the intended purpose, preferably at least 80.0 wt%, more preferably at least 85.0 wt%, 90.0 mass% or more is especially preferable.

As the content of _Al 2 _{O 3} in the porous silica particles, if 3.0 mass% or more is not particularly limited and may be appropriately selected depending on the intended purpose, 3.0% to 15 Mass% is preferred.
When the content of Al ₂ O ₃ is less than 3.0% by mass, extraction of metal (for example, cesium, lanthanum, platinum, etc.) becomes insufficient.
Of the general porous silica particles, diatomaceous earth usually contains about 3 to 13% by mass of Al ₂ O _3, but synthetic amorphous silica particles and Japanese Patent No. 4225731. The rice husk ash described in (1) contains almost no Al ₂ O ₃ (at least less than 3.0% by mass).

Further, since the composite material is obtained from the porous silica particles (for example, obtained by complexing with cyclodextrin using the porous silica particles as they are), the same color as the porous silica particles. For example, when brown diatomaceous earth is used, a brown composite material is obtained. Such coloring is caused by impurities such as Al ₂ O ₃ and other Fe ₂ O ₃ contained in the porous silica particles.
On the other hand, in the technique described in JP2011-213743A, a white or colorless composite material is obtained using a supernatant obtained by dissolving diatomaceous earth in an alkali (Examples 5 and 6 of JP2011-213743A). However, the purpose of using the supernatant is considered to be to eliminate the impurities, and the composite material obtained by the technique described in JP2011-213743A contains almost no impurities as described above. It is thought that it is not.

The content of SiO _{2 and} the content of Al ₂ O _{3 in} the porous silica particles can be determined by, for example, fluorescent X-ray elemental analysis (XRF).

In the composite material, the polymer is present on at least one of the outer surface of the porous silica particles and the pores.
And it is preferable that at least a part of the outer surface of the porous silica particles is coated with the polymer from the viewpoint of excellent metal extraction ability, particularly excellent platinum extraction ability.
The polymer is present on at least one of the outer surface of the porous silica particles and the pores, and the polymer covers at least a part of the outer surface of the porous silica particles. Can be confirmed by SEM photograph observation and elemental analysis in SEM.
For example, in an SEM photograph having a magnification of 300 to 35,000 times, when only the polymer is observed on the outer surface of the porous silica particles and the outer surface of the porous silica particles itself is not observed, It can be said that the polymer coats the entire outer surface of the porous silica particles. In addition, when the polymer is partially observed on the outer surface of the porous silica particles, it can be said that the polymer covers a part of the outer surface of the porous silica particles.

The composite material preferably has an average aspect ratio of less than 2.
The aspect ratio is calculated from the values obtained by measuring the long axis length (L) and the short axis length (S) of the particle in a scanning electron microscope image or a stereoscopic microscope image. Aspect ratio (A) = long axis length (L) / short axis length (S).
The average aspect ratio is an average value of the aspect ratios of 20 particles randomly extracted from an image.

The composite material preferably has a particle density of 0.005 g / mm ^{3 to} 0.150 g / mm ³ .
For example, the particle density is assumed to be a sphere having the same diameter as the sieve mesh using particles obtained on the sieve when the composite material is sieved. The average mass of the particles can be obtained by measuring one or several tens of weights, and can be obtained by calculating from the average mass.

(Production method of composite material)
The method for producing a composite material of the present invention includes an addition step and a polymerization step, and further includes other steps as necessary.

<Addition process>
The adding step is not particularly limited as long as it is a step of adding cyclodextrin and porous silica particles to an alkaline aqueous solution, and can be appropriately selected according to the purpose.

  Examples of the alkaline aqueous solution, the cyclodextrin, and the porous silica particles include those exemplified in the description of the composite material of the present invention.

There is no restriction | limiting in particular as temperature and time of the said addition process, According to the objective, it can select suitably.
In the addition step, stirring is preferable.
There is no restriction | limiting in particular as pH of the said alkaline aqueous solution, Although it can select suitably according to the objective, 12 or more are preferable.

  The mass ratio of the cyclodextrin and the porous silica particles added to the alkaline aqueous solution in the addition step (porous silica particles / cyclodextrin) is not particularly limited and may be appropriately selected depending on the purpose. However, 0.5 to 5 is preferable, 0.5 to 2.0 is more preferable, and 0.5 to 1.5 is particularly preferable from the viewpoint of excellent metal extraction ability.

<Polymerization process>
The polymerization step is not particularly limited as long as it is a step of adding the epoxy compound to the alkaline aqueous solution and polymerizing the cyclodextrin and the epoxy compound following the addition step, and is appropriately determined depending on the purpose. You can choose.

  Examples of the epoxy compound include those exemplified in the description of the composite material of the present invention.

  The mass ratio of the cyclodextrin and the epoxy compound in the polymerization step (cyclodextrin / epoxy compound) is not particularly limited and may be appropriately selected depending on the intended purpose. Preferably, 0.3 to 1.0 is more preferable.

There is no restriction | limiting in particular as reaction temperature of the said polymerization, Although it can select suitably according to the objective, 60 to 100 degreeC is preferable, 70 to 90 degreeC is more preferable, 75 to 85 degreeC is especially preferable. .
There is no restriction | limiting in particular as reaction time of the said polymerization, Although it can select suitably according to the objective, 1 to 10 hours are preferable, 3 to 9 hours are more preferable, and 5 to 7 hours are especially preferable. .

<Other processes>
Examples of the other steps include a filtration step, a washing step, and a drying step.

<< Filtration process >>
The filtration step is not particularly limited as long as it is a step of filtering the reaction solution after the polymerization step to separate the solid and the liquid, and can be appropriately selected according to the purpose. For example, using a funnel Can be done.

<< Cleaning process >>
The washing step is not particularly limited as long as it is a step for washing the solid obtained in the filtration step, and can be appropriately selected according to the purpose. For example, the washing step is performed using water, methanol, or the like. it can.
In the washing step, washing is preferably performed using water and methanol alternately.

<< Drying process >>
The drying step is not particularly limited as long as it is a step of drying the washed solid, and can be appropriately selected according to the purpose, but is preferably performed under reduced pressure.

(Metal extractant, cesium extractant)
The metal extractant of this invention contains the said composite material of this invention, and also contains another component as needed.
The cesium extractant of this invention contains the said composite material of this invention, and also contains another component as needed.
The metal extractant may be the composite material itself.
The cesium extractant may be the composite material itself.

  A conventional composite material using a polymer of cyclodextrin is known as a removal agent for environmental hormones and the like. However, like the metal extractant and cesium extractant of the present invention, a metal such as PGM (platinum) is used. It is not known that it can be used as a cesium extractant. In addition, the metal extractant and cesium extractant of the present invention exhibit a very excellent extraction ability as compared with conventional composite materials.

(Gas adsorbent)
The gas adsorbent of the present invention contains the composite material of the present invention, and further contains other components as necessary.
The gas adsorbent may be the composite material itself.

  Conventional composite materials using cyclodextrin polymers are known as removal agents for environmental hormones, etc., but gas adsorption (for example, methanol, methane, benzene, etc.) like the gas adsorbent of the present invention. It is not known that it can be used as an adsorbent. In addition, the gas adsorbent of the present invention exhibits a very excellent extraction capability as compared with conventional composite materials.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

<Reagents>
The following reagents were used in this example.
・ Β-CyD (β-cyclodextrin): manufactured by Nippon Shokuhin Kako Co., Ltd. ・ Diatomaceous earth: manufactured by Showa Chemical Industry Co., Ltd. ・ Sodium Hydroxide (NaOH): manufactured by Wako Pure Chemical Industries, Ltd. ・ Epichlorohydrin (epichlorohydrin): Tokyo -Kasei Sales Co., Ltd.-12N-HCl: Kanto Chemical Co., Ltd.-MeOH (Methanol): Kanto Chemical Co., Ltd.

<Diatomaceous earth>
The details of the diatomaceous earth are shown below.
Product name: Radio Light # 100 (abbreviation R- # 100)
Manufacturing category: baked product Properties: powder (light reddish brown)
True specific gravity: 2.2
<< General characteristics >>
Moisture: 3% by mass or less pH: 5.0 to 10.0
Water 2L filtration time (min 'sec "): 20'00" to 35'00 "
Cake bulk density (g / cm ³ ): 0.51 or less 150 μm residue (mass%): 3.0 or less << Example of particle size distribution (mass%) [laser method] >>
Over 40 μm: 8.2
More than 20 μm and less than 40 μm: 22.9
More than 10 μm and 20 μm or less: 25.2
More than 5 μm and 10 μm or less: 20.3
More than 2 μm and less than 5 μm: 16.4
2 μm or less: 7.0
Average particle size: 11.8 μm
<< Example of chemical analysis (mass%) >>
Ig. loss: 0.4
SiO ₂ : 90.3
Al ₂ O ₃ : 4.8
Fe ₂ O ₃ : 2.2
CaO: 0.1
MgO: 0.4
Na ₂ O: 0.1
Other: 1.7

(Examples 1-5)
<Manufacture of composite materials 1-5>
Using the reagent, composite materials 1 to 5 of cyclodextrin and porous silica particles were synthesized. The experimental method is shown below.
β-Cyclodextrin (β-CyD) and diatomaceous earth are mixed in a mass ratio of β-CyD: diatomaceous earth = 1: 1, 1: 2, 1: 3, 1: 5, 2: 1 The composite materials 1 to 5 were synthesized at a ratio.
Specifically, β-CyD was dissolved in an aqueous NaOH solution using a 300 mL three-necked flask, diatomaceous earth was then added, and stirring (320 rpm) was performed using a stirring rod with a Teflon blade. Chlorohydrin was added and reacted at 80 ° C. for 6 hours. A water-insoluble product was confirmed in the reaction solution, and the reaction was terminated when it was determined that no further insoluble components were visually formed. After completion of the reaction, the reaction solution is cooled to room temperature, 2N-hydrochloric acid aqueous solution (diluted 12N-HCl manufactured by Kanto Chemical Co., Ltd.) is added until the reaction solution becomes neutral (confirmed with pH test paper), and then Buchner funnel The resulting granular solid was thoroughly washed with water and methanol. Then, it dried at 80 degreeC under pressure reduction overnight, and the composite material was obtained.
The amount of reagent used and the yield in the synthesis are shown in Table 1 below.

In Table 1, the item “NaOH” represents the amount of NaOH used for a specific amount of water. For example, 16.02 / 40 indicates that 16.02 g of NaOH was dissolved and used in 40 mL of water.

(Comparative Example 1)
<Synthesis of composite materials using amorphous silicic acid>
Using a 300 mL three-necked flask, β-CyD (6.00026 g) was dissolved in an aqueous NaOH solution in which NaOH (8 g) was dissolved in water (30 mL), and then amorphous silicic acid (6.00018 g) was added. Then, epichlorohydrin (6.56 g) was added while stirring (320 rotations per minute) using a stirring bar equipped with a Teflon blade, and the mixture was reacted at 80 ° C. for 6 hours. A water-insoluble product was confirmed in the reaction solution, and the reaction was terminated when it was determined that no further insoluble components were visually formed. After completion of the reaction, the reaction mixture is cooled to room temperature, 2N aqueous hydrochloric acid solution is added until the reaction solution becomes neutral (confirmed with pH test paper), suction filtration is performed using a Buchner funnel, and the resulting granular solid is washed with water. And thoroughly washed with methanol. Then, it dried at 80 degreeC under pressure reduction overnight, and the composite material was obtained. The yield was 3.7043 g.
The amorphous silicate, was used by Asahi Glass Co., Ltd. high-performance spherical fine silica San Sphere (specific surface area ^{700m 2 / g~900m 2 / g)} .

<Evaluation>
<< Particle size distribution >>
About the composite material 1 synthesize | combined in Example 1, the particle size distribution was measured using the sieve.
For the measurement, 19.2402 g of the composite material 1 was used.
A multistage sieve was used as the sieve, and six kinds of sieves of 1.27 mm, 0.96 mm, 0.56 mm, 315 μm, 250 μm, and 150 μm were used.
The results are shown in FIG.

<< Particle density >>
Obtained on a sieve of 0.96 mm sieve (0.96 mm to 1.27 mm) or 0.56 mm sieve (0.56 mm to 0.96 mm) in the particle size distribution measurement. Using the obtained particles, the particles are assumed to be spheres having the same diameter as the sieve mesh, and the average mass of the particles is determined by weighing one or several tens of the particles. From there, the particle density was calculated. As a result, the particle density was 0.01 g / mm ³ . The details of the calculation are shown below.
<0.96mm-1.27mm>
Average mass (g / piece): 0.009325
Average radius (mm): 0.5575
Average volume (mm ³ ): 0.72581
Particle density (g / mm ³ ): 0.012848
<0.56mm to 0.96mm>
Average mass (g / piece): 0.001674
Average radius (mm): 0.38
Average volume (mm ³ ): 0.22985
Particle density (g / mm ³ ): 0.007282
From the average of these two points, the particle density (g / mm ³ ) = 0.01.

<< Form observation >>
-Composite material 1 of Example 1-
The SEM (scanning electron microscope) photograph of the composite material 1 obtained in Example 1 is shown in FIGS. From the SEM photograph (5,000 times) in FIG. 2, it was observed that the polymer of cyclodextrin partially covered the surface of the composite material.
Note that “Spectrum 20” in FIG. 2 is a code for indicating a site subjected to surface analysis. The same applies to FIG. 7, FIG. 10, FIG. 15, and FIG.

-Composite material of Example 2-
SEM (scanning electron microscope) photographs of the composite material 2 obtained in Example 2 are shown in FIGS. The cross-linked polymer of β-CyD was present unevenly on the surface of diatomaceous earth. Moreover, the form originating in diatomaceous earth has been confirmed.

-Composite material of Example 3-
SEM (scanning electron microscope) photographs of the composite material 3 obtained in Example 3 are shown in FIGS. A form derived from diatomaceous earth could be confirmed more clearly than the composite material 5 obtained in Example 5 described later.

-Composite material of Example 5-
SEM (scanning electron microscope) photographs of the composite material 5 obtained in Example 5 are shown in FIGS. From the surface analysis of the SEM photograph, Si was observed on the surface of the composite material. However, surface non-uniformity (roughness) was seen compared with the case where the mixing ratio of diatomaceous earth was large. This is presumably because a large amount of β-CyD polymer is produced on the surface of diatomaceous earth. Further, it was observed that a round granular polymer was formed on the surface of the composite material, and it was porous.

-Composite material 6 of Comparative Example 1
SEM (scanning electron microscope) photographs of the composite material 6 obtained in Comparative Example 1 are shown in FIGS. From the surface analysis of the SEM photograph, Si was observed on the surface of the composite material. This is presumably because SiO ₂ remains on the surface of the composite material.

<< Metal extraction experiment >>
-Cs (cesium) adsorption experiment-
1.0 g of measurement data was placed in 30 mL of a Cs solution obtained by diluting a Cs standard solution (manufactured by Kanto Chemical Co., Inc.) 20 times, and shaken at 300 strokes / min for 1 hour. After standing, the supernatant was collected, and the metal element concentration was measured using an ICP emission spectrometer (SPS3000, manufactured by SII) to obtain the extraction rate.
The following samples were used as measurement samples. The measurement results of the extraction rate are shown in FIG.
-Composite material obtained in Example 1: Extraction rate = 97.85%
-Composite material 2 obtained in Example 2: Extraction rate = 98.08%
-Composite material 6 obtained in Comparative Example 1: Extraction rate = 9.17%
-Diatomaceous earth: Extraction rate = 35.98%
It was confirmed that the composite material 1 and the composite material 2 had a very excellent Cs extraction ability about 10.7 times that of the composite material 6 and about 2.7 times that of diatomaceous earth.

-Metal extraction ability from PGM (platinum group element) solution-
Platinum group metals (PGM) containing Al, Ba, Ce, La, Pd, Pt, Rh, Y, Zr (La: 11.82 ppm, Pd: 6.66 ppm, Pt: 2.47 ppm, Rh) : 3.11 ppm, Zr: 2.26 ppm) diluted with ion-exchanged water 500 times (PGM solution). In 30 mL of this PGM solution, 1.0 g of a measurement sample was placed and shaken at 300 strokes / min for 1 hour. After standing, the supernatant was collected, and the metal element concentration was measured using an ICP emission spectrometer (SPS3000, manufactured by SII) to obtain the extraction rate.
The following samples were used as measurement samples. The measurement result of the extraction rate is shown in FIG.
-Composite material 1 obtained in Example 1
-Composite material 3 obtained in Example 3
-Composite material 6 obtained in Comparative Example 1
・ Diatomaceous earth

The composite material 1 (β-CyD: diatomaceous earth = 1: 1) showed a high extraction ability of about 80% with respect to Pt. The extraction capacity was about 30% for Rh and about 50% for La and Pd.
The extraction capacity of the composite material 3 (β-CyD: diatomaceous earth = 1: 3) is not significantly different from the extraction capacity of the composite material 1 for La, Pd, and Rh, but about 10% for Pt. It fell greatly. From the surface observation by SEM, it is considered that this is because the composite material 3 has a large amount of diatomaceous earth itself and the surface is not sufficiently covered with the polymer of β-CyD. On the other hand, from the surface observation of the composite material 1 by SEM, it was confirmed that no diatomaceous earth was observed on the surface of the composite material 1 and the surface was covered with the polymer of β-CyD.
From this, it is speculated that the composite material 1 and the composite material 3 have different specific surface areas, and that the composite material 1 has a structure close to a porous structure. The composite material 1 is presumed to have an increased Pt extraction ability due to the difference in structure and the composite factor between the CyD polymer and diatomaceous earth. The extraction ability of Zr is almost 100% in diatomaceous earth, whereas in the composite material, the extraction ability increases in the order of composite material 6, composite material 1, and composite material 3 as the proportion of diatomaceous earth increases. This suggests that diatomaceous earth on the surface of the composite material affects the metal extraction ability.

Furthermore, in order to examine the extraction ability in more detail, each measurement sample was ground with a mortar, and a metal extraction experiment was performed in the same manner. The result is shown in FIG.
From FIG. 25, the tendency for the extraction ability to increase was generally observed when ground in a mortar. This is because the increase in the specific surface area caused by crushing the composite material and the appearance of cyclodextrin existing inside the porous silica particles of the composite material on the surface of the polymer affected the extraction ability. Guessed. However, since the extraction of Pt does not show a great change in either sample, it is considered that the composition of the particle surface is more involved in the extraction ability of Pt than the particle size.

From the above results, metal extraction ability was not seen in the composite material 6 of Comparative Example 1 in which β-CyD was polymerized in the presence of amorphous silica. Moreover, only diatomaceous earth showed extractability only for Zr. It has been clarified that by extracting the porous silica particles containing 3.0% by mass or more of Al ₂ O ₃ and cyclodextrin, metal extraction ability for rare metals and the like is expressed.
It has also been clarified that the metal extraction ability is greatly influenced by the respective compounding ratios and particle sizes.

<< Other properties (vapor adsorption capacity) >>
The composite material 1 was examined for its ability to adsorb vapor with respect to methanol. The results are shown in FIG.
The adsorption isotherm is measured using an adsorption isotherm measuring device (Belsorb 18, manufactured by Bell Japan), an air high-temperature bath temperature of 50 ° C., an adsorption temperature of 25 ° C., an initial introduction pressure of 0.4 torr, a saturated vapor pressure of 127.05 mmHg, and an equilibrium. It calculated | required on condition of time 300 seconds.
From FIG. 26, the methanol adsorption amount of the composite material 1 was about 110 mL per 1 g. The type of adsorption isotherm is type II, and it is considered that the mutual force between methanol and the sample is relatively strong. This is presumably because methanol was adsorbed in many vacancies present on the particle surface and in the vacancies of cyclodextrin, which became clear from the SEM image.
From this result, it was confirmed that the composite material of the present invention has a vapor adsorption ability. Adsorption of other solvents (ethanol, acetone, benzene, etc.) can also be expected. Furthermore, adsorption of gaseous molecules (hydrogen, methane, carbon dioxide, etc.) can also be expected.

Since the composite material of the present invention is excellent in metal extraction ability, it can be suitably used as a metal extractant useful for extraction of metals from waste or the like in the environment.
Since the composite material of the present invention is excellent in gas adsorption capacity, it can be suitably used as a gas adsorbent.

Claims (12)

A polymer of cyclodextrin;
Containing 3.0 mass% or more of Al ₂ O ₃ and porous silica particles having a plurality of pores,
The composite material, wherein the polymer is present on at least one of the outer surface of the porous silica particles and the pores.   The composite material according to claim 1, wherein the porous silica particles are diatomaceous earth.   The composite material according to claim 1, wherein the polymer of cyclodextrin is obtained by polymerizing cyclodextrin and an epoxy compound.   The composite material according to claim 3, wherein the epoxy compound contains an epihalohydrin.   The composite material according to any one of claims 1 to 4, wherein at least a part of the outer surface of the porous silica particles is coated with a polymer of cyclodextrin.   A metal extractant comprising the composite material according to claim 1.   A cesium extractant comprising the composite material according to claim 1.   A gas adsorbent comprising the composite material according to claim 1. An addition step of adding cyclodextrin and porous silica particles containing 3.0% by mass or more of Al ₂ O ₃ and having a plurality of pores to the alkaline aqueous solution;
Subsequent to the addition step, a method for producing a composite material comprising a polymerization step of adding an epoxy compound to the alkaline aqueous solution and polymerizing the cyclodextrin and the epoxy compound.   The method for producing a composite material according to claim 9, wherein the epoxy compound contains epihalohydrin.   The method for producing a composite material according to claim 9, wherein the porous silica particles are diatomaceous earth.   The composite according to any one of claims 9 to 11, wherein a mass ratio of the cyclodextrin and the porous silica particles (porous silica particles / cyclodextrin) added to the alkaline aqueous solution in the adding step is 0.5 to 5. Material manufacturing method.