JP2021115563A - Granular structure - Google Patents

Abstract

To provide a granular structure, which is a granule by porous particles and in which the original adsorption capacity or catalytic activity of the porous particles can be sufficiently exhibited, and the particle strength is also high.SOLUTION: Provided is a granular structure, which is a granular structure in which hydrophilic porous particles are bonded to each other via a binder, and in which the percentage of voids having an area of 30 μm2 or more in the center cross-sectional area of the granular structure is 5% or more and 15% or less at the time of drying, and the water-containing capacity obtained by subtracting the percentage at the time of water impregnation from the percentage at the time of drying is 4% or more and 15% or less, and the particle strength of the granular structure is 400 gf/mm2 or more and 2000 gf/mm2 or less.SELECTED DRAWING: None

Description

The present invention relates to granular structures used in aqueous media.

For the adsorbent used for removing harmful substances in water, the catalyst used for chemical reaction in an aqueous medium, etc., a granular structure made by granulating porous particles with a binder for convenience during use. Is used.

For the granulation in this case, a granulation method such as a rolling granulation method, an extrusion granulation method, or a spray drying method is used. For example, in Patent Document 1, a specific pore is formed by a spray drying method. It is described to produce agglomerates of radioactive decontamination particles with volume.

Japanese Unexamined Patent Publication No. 2014-228282

Here, in order to exert the adsorption capacity originally possessed by the porous particles in the granular structure after granulation and to delay the fracture in the fracture curve as much as possible, not only the porosity inside the particles is increased, but also the voids. It is necessary to design a gap that has communication with the outside in order to make it easier for water to enter the space. However, the conventional granulation method has not been able to sufficiently exhibit the original adsorption capacity of the porous particles (adsorbent powder).

That is, it is considered that the granulated product obtained by the rolling granulation method or the extrusion granulation method has a relatively small porosity and therefore impairs the original adsorption capacity of the porous particles. Furthermore, in the rolling granulation method, since the particle size distribution after granulation is broad, operations such as crushing coarse particles or re-granulation of fine powder are performed in order to produce particles having the required particle size. Is required, and the yield tends to be poor.

On the other hand, in the spray drying method, not only the porosity of the obtained granulated product is large and the original adsorption capacity can be exhibited, but also the particle size distribution after granulation is sharp, and particles having the required particle size are produced with good yield. be able to. However, the spray drying method is not a sustainable method because it uses a large amount of water and heat. Further, since the particle strength of the granulated product is low, it cannot be said that it is suitable for granulation for applications where the strength of an adsorbent, a catalyst, etc. is required.

Therefore, the present invention relates to a granular structure that is a granulated product of porous particles, has a high original adsorption capacity of the porous particles, can sufficiently exhibit catalytic activity, and has high particle strength.

As a result of examining various granulation methods, the present inventors have found that the porosity is high and the original adsorption capacity of porous particles is high according to the granulation method using a container rotary granulation machine and a multi-fluid nozzle. The present invention has been completed by finding that a granular structure capable of sufficiently exhibiting catalytic activity and having sufficient particle strength can be produced with good yield.

The present invention is a granular structure in which hydrophilic porous particles are bonded to each other via a binder, and the ratio of voids having an area ^{of 30 μm 2 or more in the central cross-sectional area of the granular structure is when dried.} 5% or more and 15% or less, the water content obtained by subtracting the ratio at the time of water impregnation from the ratio at the time of drying is 4% or more and 15% or less, and the particle strength of the granular structure is 400 gf /. It provides a granular structure of ^{mm 2} or more and 2000 gf / mm ^{2 or less.}

The granular structure of the present invention is obtained by granulating porous particles with a binder, and can sufficiently exert the original adsorption capacity or catalytic activity of the porous particles, and has sufficient particle strength.

It is an adsorption isotherm which plotted the adsorption amount with respect to the equilibrium supernatant concentration when A type zeolite was used as a porous particle. It is a Langmuir plot which plotted the divisor by the adsorption amount of the equilibrium supernatant concentration with respect to the equilibrium supernatant concentration when A type zeolite was used as a porous particle.

[Granular structure]
From the viewpoint of exerting the original adsorption capacity of the porous particles, the granular structure of the present invention ^{occupies the ratio of voids having an area of 30 μm 2} or more in the cross-sectional area (hereinafter, may be simply referred to as “porosity”). However, when dried, it is 5% or more, preferably 6% or more, more preferably 7% or more, still more preferably 7.5% or more, and also from the viewpoint of maintaining the particle strength and the bulk specific gravity of the granular structure. Therefore, it is 15% or less, preferably 14% or less, more preferably 12% or less, and further preferably 10% or less.

Further, the granular structure of the present invention has a water content capacity of 4% or more obtained by subtracting the porosity at the time of water impregnation from the porosity at the time of drying from the viewpoint that water easily enters the voids. It is preferably 5% or more, more preferably 5.5% or more, still more preferably 6% or more, and from the viewpoint of maintaining particle strength, it is 15% or less, preferably 14% or less, more preferably 12%. Below, it is more preferably 10% or less.

In the present invention, the porosity of the granular structure is measured by putting the granular structure in a glass capillary and using image processing software ImageJ to obtain a powder cross-sectional image obtained by using X-ray CT (manufactured by Bruker Micro CT). Was used for the analysis. That is, the cross-sectional image of the center of the powder was binarized, and the ratio of the void area to the powder area was calculated to obtain the powder porosity. The detectable void size is the device resolution (0.8 μm).

^{Further, the granular structure of the present invention preferably has a particle strength of 400 gf / mm 2} or more, preferably from the viewpoint that it can be suitably used for applications requiring strength such as an adsorbent and a catalyst. 450 gf / mm ² or more, more preferably 500 gf / mm ² or more, more preferably not more 550gf / mm ² or more, from the viewpoint of facilitating the compacting process after performing the adsorption, etc., 2000 gf / mm ² or less a is preferably 1800gf / mm ² or less, more preferably 1500gf / mm ^2, more preferably not more than 1200 gf / mm ^2.

Examples of the hydrophilic porous particles used for granulating the granular structure of the present invention include zeolite, silicotitanate, ferrocyanide, and titanic acid, and among them, type A zeolite, which is a kind of zeolite, mordenite, and the like. Clinopeptide and chabasite are preferred.

The pore ratio of the hydrophilic porous particles is preferably 15% or more, more preferably 18% or more, still more preferably 20% or more, and maintaining the skeleton of the crystal structure from the viewpoint of obtaining a sufficient adsorption capacity. From this point of view, it is preferably 60% or less, more preferably 55% or less, still more preferably 50% or less.

From the viewpoint of improving the adsorption efficiency, the average particle size of the hydrophilic porous particles is preferably 1 μm or more, more preferably 2 μm or more, still more preferably 3 μm or more, and the ease of forming a granular structure. From the viewpoint, it is preferably 100 μm or less, more preferably 50 μm or less, still more preferably 10 μm or less, still more preferably 7 μm or less.

Examples of the binder used for granulating the granular structure of the present invention include silicates, fatty acids, waxes and the like, and silicates are particularly preferable. From the viewpoint of forming a granular structure, the silicate preferably contains one or two selected from sodium silicate and potassium silicate, and more preferably sodium silicate. The total content of sodium silicate and potassium silicate in the silicate is preferably 95% by mass or more, more preferably 99% by mass or more, still more preferably 99.5% by mass or more, still more preferably substantially 100% by mass. be.

Examples of sodium silicate include sodium metasilicate (Na ₂ SiO ₃ ), sodium orthosilicate (Na ₄ SiO ₄ ), sodium disilicate (Na ₂ Si ₂ O ₅ ), and sodium tetrasilicate (Na ₂ Si ₄ O _9). ) And their hydrates. As the sodium silicate material, in addition to sodium silicate Nos. 1, 2 and 3 described in JIS K1408, water glass having various molar ratios can be usually used.

Sodium silicate is generally represented by the molecular formula of _{Na 2} O, nSiO ₂ , mH _{2 O.} The coefficient n (molecular ratio of SiO _{2 to Na 2} O) is called a molar ratio and can be expressed by the following formula.

The physical properties of sodium silicate differ depending on the molar ratio, but from the viewpoint of improving handleability when using a granular structure, the molar ratio is preferably 2.0 or more, more preferably 2.4 or more, still more preferably 2.8 or more, and further. It is preferably 3.0 or more, and is preferably 4.0 or less, more preferably 3.5 or less, still more preferably 3.3 or less, from the viewpoint of improving sprayability during production.

The mass ratio (binder / hydrophilic porous particles) of the binder constituting the granular structure of the present invention to the hydrophilic porous particles is preferably 0.05 or more from the viewpoint of improving the handleability when using the granular structure. It is more preferably 0.1 or more, still more preferably 0.2 or more, and from the viewpoint of adsorption efficiency, it is preferably 1 or less, more preferably 0.8 or less, still more preferably 0.7 or less.

The average particle size of the granular structure of the present invention is preferably 50 μm or more, more preferably 80 μm or more, still more preferably 100 μm or more, and improving the adsorption efficiency from the viewpoint of improving the handleability when using the granular structure. From this point of view, it is preferably 2000 μm or less, more preferably 1000 μm or less, and further preferably 800 μm or less.

〔Production method〕
The granular structure of the present invention includes a step of granulating hydrophilic porous particles in a rotating container rotary granulator by spraying an aqueous solution of a binder with a multi-fluid nozzle (hereinafter, "" It can be produced by the "spray agglomeration method").

In general, according to the granulation method using a container rotary type granulator, the powder can be uniformly flowed, and further, the mixing mechanism accompanied by lifting of particles by rotation and sliding / falling by its own weight is used. The shearing force applied to the powder is suppressed. Therefore, the granulation method using the container rotary type granulator can be said to be a non-consolidation granulation method. As a result, the granular structure of the present invention obtained by the above method has a large porosity as compared with the granulated product obtained by another granulation method.

Further, according to the granulation method, a granulated product having a suitable particle size can be obtained in good yield. It is considered that this is because a large liquid mass formed by coarse particles is not generated by spraying the binder as droplets of a fine aqueous solution in advance using a multi-fluid nozzle and supplying it into the container rotary granulator. Be done.

In the above-mentioned production method, the binder concentration in the aqueous solution of the binder to be sprayed is preferably 10% by mass or more, more preferably 20% by mass or more, from the viewpoint of making the concentration suitable for binding the hydrophilic porous particles to each other. It is more preferably 30% by mass or more, and is preferably 65% by mass or less, more preferably 60% by mass, from the viewpoint of handleability and spraying as droplets to suppress coarse particle formation and increase the strength of the granular structure. % Or less, more preferably 58% by mass or less. The binder concentration (solid content) in the aqueous binder solution can be determined by the method described in Examples.

Further, the binder aqueous solution may contain a polymer, inorganic particles or the like as long as the effect of the present invention is not impaired, or may contain a lower alcohol having 1 to 3 carbon atoms.

(Container rotary granulator)
As the container rotary type granulator, a drum type granulator and a pan type granulator are preferable. The drum-type granulator is not particularly limited as long as the drum-shaped cylinder rotates to perform processing. Horizontal or slightly tilted drum granulators can also be used. These devices may be of either a batch type or a continuous type.

If the wall friction coefficient between the hydrophilic porous particles and the inner wall of the container rotary granulator is small and it is difficult to apply sufficient ascending kinetic force to the hydrophilic porous particles, the particles are mixed with the inner wall of the container. It is preferable to provide a plurality of baffles to assist the movement. By providing the baffle plate, it becomes possible to impart an ascending motion to the hydrophilic porous particles, and the powder mixability and the solid-liquid mixability are improved.

The operating conditions of the container rotary granulator are not particularly limited as long as the hydrophilic porous particles in the granulator can be flowed as uniformly as possible and stirred. From the viewpoint of producing a granular structure having sufficient particle strength with good yield, the Froude number defined by the following formula is preferably 0.005 or more, more preferably 0.01 or more, and further preferably 0.05 or more. Preferably, from the viewpoint of obtaining a non-consolidated granule, it is preferably 1.0 or less, more preferably 0.6 or less, and further preferably 0.4 or less.

In a drum type granulator or a pan type granulator in which granulation proceeds by the rotation of the main body body, V and R use the values of the main body body, and horizontal or vertical type having a main wing and a crushing wing. In the granulation machine, the values of the spindle are used for V and R, and in the bread type granulator equipped with the crushing blade, the values of the crushing blade are used for V and R.

(Multi-fluid nozzle)
In the present invention, an aqueous solution of the binder is supplied using a multi-fluid nozzle. By using a multi-fluid nozzle, the droplets can be made finer and dispersed. A multi-fluid nozzle is a nozzle that mixes and atomizes liquid and atomizing gas (air, nitrogen, etc.) through independent flow paths to the vicinity of the nozzle tip, and is a two-fluid nozzle, a three-fluid nozzle, and four. A fluid nozzle and the like can be mentioned. Further, the mixing portion of the binder aqueous solution and the atomizing gas may be either an internal mixing type that mixes inside the nozzle tip or an external mixing type that mixes outside the nozzle tip.

Such multi-fluid nozzles include internal mixing type two-fluid nozzles manufactured by Spraying Systems Japan, Kyoritsu Alloy Mfg. Co., Ltd., Ikeuchi Co., Ltd., Spraying Systems Japan Co., Ltd., Kyoritsu Alloy Mfg. Co., Ltd. Examples include an external mixing type two-fluid nozzle manufactured by Max, and an external mixing type four-fluid nozzle manufactured by Fujisaki Electric Co., Ltd.

Further, the droplet diameter of the binder aqueous solution can be adjusted to a desired range by adjusting the balance between the flow rate of the binder aqueous solution and the flow rate of the atomizing gas. That is, in order to reduce the droplet diameter, the flow rate of the atomizing gas may be increased with respect to the binder aqueous solution having a constant flow rate, and the flow rate of the binder aqueous solution may be increased with respect to the atomizing gas having a constant flow rate. It should be lowered.
For example, when a two-fluid nozzle is used, it is easy to adjust the flow rate of the atomizing gas by adjusting the spray pressure of the atomizing gas. The gas spray pressure for atomization is preferably 0.05 MPa or more from the viewpoint of liquid dispersion, and preferably 1 MPa or less from the viewpoint of equipment load. The spray pressure of the aqueous binder solution is not particularly limited, but is preferably 1 MPa or less from the viewpoint of equipment load.

The average particle size of the droplet diameter of the aqueous binder solution is preferably 200 μm or less, more preferably 150 μm or less, still more preferably 100 μm or less, from the viewpoint of producing a granular structure having sufficient particle strength with good yield, and is used. From the viewpoint of improving the handleability of the above, it is preferably 10 μm or more, more preferably 20 μm or more, still more preferably 30 μm or more, still more preferably 50 μm or more.

The smaller the droplet diameter, the lower the flow rate of the binder aqueous solution and the lower the productivity. For example, by using multiple multi-fluid nozzles and reducing the flow rate per nozzle, while maintaining the fineness of the droplets. The addition rate can be increased. The number of multi-fluid nozzles may be one or more, but 2 to 20 may be used.

The average particle size of the droplet diameter of the binder aqueous solution is calculated on a volume basis, and is a value measured using, for example, a laser diffraction type particle size distribution measuring device (Malburn Co., Ltd., Spray Tech). ..

The temperature of the binder aqueous solution when the binder aqueous solution is sprayed using the multi-fluid nozzle is preferably 5 to 50 ° C., more preferably 10 to 30 ° C. from the viewpoint of spray stability.
The addition rate of the binder aqueous solution is preferably 35 parts by mass or less, more preferably 20 parts by mass or less, based on 100 parts by mass of the hydrophilic porous particles from the viewpoint of obtaining a granulated product having a sharp particle size distribution. It is more preferably 10 parts by mass or less, preferably 1 part by mass or more, more preferably 2 parts by mass or more, and further preferably 3 parts by mass or more. The above range is suitable when soda No. 1, No. 2 or No. 3 described in JIS K1408 is used.

From the same viewpoint as above, the rate of addition of the binder (solid content) is preferably 30 parts by mass or less, more preferably 18 parts by mass or less, based on 100 parts by mass of the hydrophilic porous particles. It is more preferably 9 parts by mass or less, preferably 0.4 parts by mass or more, more preferably 0.8 parts by mass or more, and further preferably 1.2 parts by mass or more.

(Dry)
In the present invention, it is preferable to further dry the obtained granular structure from the viewpoint of increasing the particle strength and obtaining a stable granulated product even when the structure is used in water. Examples of the drying method include shelf drying, fluidized bed drying, vacuum drying, microwave drying and the like. Of these, shelf drying and fluidized bed drying are preferable from the viewpoint of equipment.

From the viewpoint of suppressing the collapse of the granular structure during drying, a drying method in which a strong shearing force is not applied as much as possible is preferable. For example, in the batch type, a method of drying with an electric shelf dryer or a hot air dryer, a method of drying with a batch type fluidized bed, etc. are mentioned, and in the continuous type, a fluidized bed, a rotary dryer, a steam tube dryer, etc. are mentioned. Be done.

The drying temperature can be appropriately determined in consideration of the drying rate, but is preferably 60 ° C. or higher, more preferably 100 ° C. or higher, still more preferably 120 ° C. or higher. Further, from the viewpoint of reducing the heat load, the upper limit thereof is preferably 300 ° C. or lower, more preferably 250 ° C. or lower, and further preferably 200 ° C. or lower.

The drying time varies depending on the effective amount and amount of the aqueous binder solution used in the production, but is appropriately adjusted so that the particle strength of the granular structure is within the above range. The drying time is usually about 10 minutes to 24 hours, more preferably about 20 minutes to 15 hours, and even more preferably about 30 minutes to 8 hours.

The amount of water in the obtained granular structure is preferably 10% by mass or less, more preferably 7% by mass or less, from the viewpoint of increasing the particle strength and making the structure a stable granulated product even when used in water. It is more preferably 5% by mass or less, preferably 0.5% by mass or more, more preferably 0.8% by mass or more, still more preferably 0.5% by mass or less from the viewpoint of productivity.

[Use]
The granular structure of the present invention is useful as an adsorbent for harmful substances in water, a catalyst for a liquid phase reaction system of a polar solvent, and the like. For example, it can be used for treatment of contaminated water containing radioactive substances in nuclear power generation, treatment of wastewater containing harmful metals and organic substances discharged from factories, hydrogenation catalyst for processing fats and oils, and the like.

Examples 1-2, Comparative Examples 1-3
A granular structure was produced by the production methods shown in Examples 1 and 2 and Comparative Examples 1 and 3 using type A zeolite or mordenite as the porous particles and sodium silicate as the binder. Table 1 shows the composition of the raw materials used for producing the granular structure, the composition of the obtained granular structure, the average particle size and the water content. The water content of the granular structure was measured as follows.

<Measurement of water content of granular structure>
2 g of the sample was evenly sprayed on an aluminum container with a diameter of 11.5 cm, and then using an infrared moisture meter (manufactured by Kett Science Institute Co., Ltd., FD240), the temperature was 105 ° C in the humidity standard moisture measurement mode, Auto. It was calculated by excluding the volatile free water measured under the conditions of (the measurement is completed when the amount of change in the measured value is within 0.05% in 30 seconds as the final measured value). The water content shown in Table 1 is an external ratio to the solid content.

-Example 1 (spray agglutination method)
A type zeolite (manufactured by Zeobuilder, trade name: zeolite (powder), average particle size of about 3 μm) is put into a 75 L drum type granulator (φ40 cm × L60 cm) having a baffle plate at the blending ratio shown in Table 1. Sodium silicate aqueous solution (manufactured by Fuji Chemical Co., Ltd., trade name: sodium silicate No. 3, molar ratio: 3.0 to 3.3, zeolite degree) while mixing under the conditions of drum rotation speed 30r.pm / fluid number 0.2 / drum angle 12.6 ° : 40-53, solid content: 54.3%) was spray-added using one external mixing type two-fluid nozzle (manufactured by Atmax) to granulate. The batch size is 6.9 kg. The median diameter of the spray droplet diameter of the sodium silicate aqueous solution was 69 μm.
After spraying the sodium silicate aqueous solution, mixing was continued for 1 minute, the mixture was discharged from the drum type granulator, and dried at 150 ° C. for 720 minutes using an electric dryer to obtain the granular structure of Example 1.

-Comparative example 1 (spray granulation method)
Type A zeolite (manufactured by Zeolite, trade name: zeolite (powder), average particle size of about 3 μm) and aqueous sodium silicate solution (manufactured by Fuji Chemical Co., Ltd., trade name: sodium silicate No. 3) with the blending ratios shown in Table 1. (Mole ratio: 3.0 to 3.3, Baume degree: 40 to 53, Solid content: 54.3%) and water are mixed with a turbine blade (DHC-10 manufactured by Inoue Seisakusho Co., Ltd.) to obtain a water slurry having a solid content of 50.0%. Obtained. The water slurry was prepared by first adding water to the mixing tank, then adding an aqueous sodium silicate solution, and then adding zeolite and mixing.
The obtained water slurry was spray-dried at a blowing temperature of 170 ° C. to obtain a granular structure of Comparative Example 1.

-Comparative example 2 (rolling granulation method)
A type A zeolite (manufactured by Zeobuilder, trade name: zeolite (powder), average particle size of about 3 μm) is mixed with a 2 L high-speed mixer (manufactured by Fukae Pautech: LFS-2, agitator rotation speed 300 r. Sodium silicate aqueous solution (manufactured by Fuji Chemical Industry Co., Ltd., trade name: sodium silicate No. 3, solid content: 55.1%) was added dropwise while mixing with pm, chopper rotation 1300r.pm), and rolling granulation was performed. The batch size is 0.3 kg. The median diameter of the dripping droplet diameter of the sodium silicate aqueous solution was about 500 μm.
After dropping the aqueous sodium silicate solution, mixing was continued for 5 minutes, the mixture was discharged from a 2 L mixer, and dried at 120 ° C. for 4 hours using an electric shelf dryer to obtain a granular structure of Comparative Example 2.

-Comparative example 3 (extrusion granulation method)
A-type zeolite (manufactured by Zeolite, trade name: zeolite (powder), average particle size of about 3 μm) is mixed with a Nauter mixer (manufactured by Hosokawa Micron, LV-1, maximum rotation speed) at the blending ratios shown in Table 1. However, an aqueous sodium silicate solution (manufactured by Fuji Chemical Industry Co., Ltd., trade name: sodium silicate No. 3, solid content: 55.1%) was added dropwise. The batch size is 0.6 kg. The median diameter of the dripping droplet diameter of the sodium silicate aqueous solution was about 500 μm.
After dropping the aqueous sodium silicate solution, mixing was continued for 10 minutes, and then the mixture was discharged from the mixer. The extracted mixture was extruded and granulated using Dome Gran (manufactured by Dalton: DG-L1, φ1.5 mm screen, rotation speed 50 rpm). The extruded granules are received in a vat, granulated with a power mill (Dalton: P-02S, φ5.0 mm screen), and then dried at 140 ° C for 4 hours using an electric shelf dryer for comparison. The granular structure of Example 3 was obtained.

-Example 2 (spray agglutination method)
Froude number (manufactured by Tosoh Corporation, trade name: HSZ-642NAA, average particle size 12 μm) was put into a 75 L drum type granulator (φ40 cm × L60 cm) having a baffle plate at the blending ratio shown in Table 1, and the drum rotation speed. Sodium silicate aqueous solution (manufactured by Fuji Chemical Co., Ltd., trade name: No. 3 sodium silicate, molar ratio: 3.0 to 3.3, Baume degree: 40 to 53, while mixing under the conditions of 30r.pm / Froude number 0.2 / Drum angle 12.6 ° Solid content: 54.3%) was spray-added using one external mixed two-fluid nozzle (manufactured by Atmax) to granulate. The batch size is 8.9 kg. The median diameter of the spray droplet diameter of the sodium silicate aqueous solution was 69 μm.
After spraying the sodium silicate aqueous solution, mixing was continued for 1 minute, the mixture was discharged from the drum type granulator, and dried at 150 ° C. for 720 minutes using an electric dryer to obtain the granular structure of Example 2.

Test example (evaluation of granular structure)
With respect to the granular structures of Examples 1 and 2 and Comparative Examples 1 to 3 obtained above, the saturated adsorption capacity of the porous particles, the breakthrough capacity of the granular structure, the porosity, the water content capacity, and the particle strength were measured. The results are shown in Table 3. Each granular structure was sieved and those in the particle size range shown in Table 3 were used for the following measurements.
As a reference example, natural zeolite was also measured in the same manner, and the results are also shown in Table 3.
As the granular structure of natural zeolite, Z-05 (particle size 0.5 to 1.0 mm) manufactured by Siegrite Co., Ltd. was used. Since a small amount of fine powder is present as it is, the fine powder was removed by washing with water before evaluation. As the porous particles, SGW (particle size 10 μm) manufactured by Siegrite Co., Ltd. was used. SGW is a crushed product of Z-05.

<Measurement method of saturated adsorption capacity of porous particles>
For 100 mL of CsCl aqueous solution of 300, 500, 800, 1000, 5000, 10000, 15000 ppm, weigh 1 g of porous particles in a 100 mL beaker, and stir for 24 hours using a stirrer piece to obtain the equilibrium supernatant concentration of Cs below. It was measured by the method of. The adsorption amount was calculated from the initial concentration and the equilibrium supernatant concentration.
When A-type zeolite was used as the porous particles, the adsorption isotherm plotting the adsorption amount with respect to the equilibrium supernatant concentration was plotted in FIG. 1, and the divisor by the adsorption amount of the equilibrium supernatant concentration with respect to the equilibrium supernatant concentration was plotted in FIG. The Langmuir plot is shown.
The following Langmuir equation (1) was modified to calculate the saturated adsorption capacity of porous particles from the slope of equation (2) representing the Langmuir plot.

<Measurement method of breakthrough capacity of granular structure>
2.0 g of the granular structure produced in the above Examples and Comparative Examples was placed in a column having a capacity of 2 mL (Econo Column Chromatography Column # 7370707 manufactured by Bio-Radola Volatries), and an SJ-1211II-L Perista pump manufactured by Atto Co., Ltd. was used. A 1000 ppm CsCl solution was flowed at a flow rate of 1 mL / min, fractionated by 10 mL each with a fraction collector DC-1000 manufactured by Tokyo Rika Kikai Co., Ltd., and the Cs concentration was analyzed by the following method to obtain a breakthrough curve. The time when the concentration exceeded 1% of the initial concentration was defined as the breakthrough time, and the adsorption amount up to that time was defined as the breakthrough capacity of the granular structure.

(Measuring method of Cs concentration)
An inductively coupled plasma mass spectrometer <ICP-MS> was used to measure the Cs concentration. The device used Thermo Fisher Scientific iCAP Qs and ^{measured 133} Cs in He collision mode. The calibration curve was prepared by diluting with 1% nitric acid using a standard solution for atomic absorption <Cs 1000 μg / mL manufactured by Kanto Chemical Co., Inc.>. The sample was prepared by diluting with 1% nitric acid so as to be within the calibration curve range, and was used for measurement.

(Measuring method of porosity)
The porosity was measured in full scanning mode using an X-ray CT device (SKYSCAN1272, manufactured by Bruker Micro CT). The measurement conditions were a voltage value of 50 kV, a current value of 200 μA, a resolution of 4904 × 3280 pixels, and a resolution of 0.8 μm. The acquired image was binarized by setting the threshold value to 35 using the image processing software ImageJ, and the void ratio with a ^{void area of 30 μm 2 or more was calculated by the command Analyze Particles in ImageJ.}

(Measurement method of particle strength)
Using a particle hardness measuring device (Grano manufactured by Okada Seiko Co., Ltd.), one granular structure is placed on the stage inside the device, the indenter is lowered at a speed of 100 μm / sec, and the load when the granular structure collapses is applied. It was measured. At this time, 10 granular structures were measured and shown as a number average value.

Claims (8)

A granular structure in which hydrophilic porous particles are bonded to each other via a binder, and the ratio of voids having an area ^{of 30 μm 2 or more in the central cross-sectional area of the granular structure is 5% or more when dried.} It is 15% or less, the water content obtained by subtracting the ratio at the time of water impregnation from the ratio at the time of drying is 4% or more and 15% or less, and the particle strength of the granular structure is 400 ^{gf / mm 2} or more 2000 gf. Granular structure less than / mm ^2. The granular structure according to claim 1, wherein the mass ratio (binder / hydrophilic porous particles) of the binder constituting the granular structure and the hydrophilic porous particles is 0.05 or more and 1 or less. The granular structure according to claim 1 or 2, wherein the hydrophilic porous particles are zeolite. The granular structure according to any one of claims 1 to 3, wherein the binder is a silicate. The granular structure according to any one of claims 1 to 4, wherein the hydrophilic porous particles have a pore ratio of 15% or more and 60% or less. The granular structure according to any one of claims 1 to 5, which is an adsorbent for harmful substances in water. The granular structure according to any one of claims 1 to 5, which is a catalyst for a liquid phase reaction system of a polar solvent. It is obtained by a method including a step of granulating by spraying an aqueous solution of a binder on a hydrophilic porous particle in a rotating container rotary granulator with a multi-fluid nozzle. 7. The granular structure according to any one of 7.

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