JP2020011211A - Method for producing adsorbent - Google Patents

Abstract

To provide a method for producing adsorbent, in which an adsorbent can be produced using various materials.SOLUTION: In the method for producing an adsorbent, a liquid containing nanoparticles that include iron is penetrated into pores of a porous material, and the liquid is dried. The nanoparticles contain iron oxide and after drying the liquid, the iron oxide may be reduced. The pressure may be reduced in a state in which the porous material is immersed in the liquid. In the method for producing the adsorbent, powdery nano-particles may be put in the pores of the porous material. In a state where the porous material is submerged in the powdery nanoparticle, an airflow may be generated from outside the porous material toward the pores.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing an adsorbent. In particular, the present invention relates to a method for producing an adsorbent for adsorbing phosphorus.

  2. Description of the Related Art In order to reduce the amount of carbon dioxide in the atmosphere, a technique for artificially capturing and storing carbon dioxide in the ground is known. For example, it is possible to absorb carbon dioxide in the atmosphere using biomass such as wood and agricultural crops, and fix the carbon dioxide as organic carbon. However, since these biomass are organic substances, even if they are stored in the ground as they are, they will only rot and decompose and will re-emit carbon dioxide to the atmosphere. On the other hand, when biomass is heated in a state where oxygen is cut off, oxygen atoms and hydrogen atoms are desorbed, and a carbide composed of carbon and ash can be generated. Since this carbide is a lump of carbon, it is not burned in the presence of oxygen unless heated at a high temperature. That is, the carbide is very stable in the environment (underground) and hardly decomposed. By burying carbonized biomass in farmland or the like in this way, carbon dioxide can be converted to carbon and sequestered and stored underground. In other words, burying biomass carbide in the ground leads to a reduction in the amount of carbon dioxide in the atmosphere. Further, the carbide has an effect of improving the soil quality of the soil. However, in consideration of the cost of producing carbides, simply using the carbides only for improving the soil quality of the soil is not worth the production costs.

  On the other hand, it is known that carbides are porous and therefore have a very large surface area. Utilizing this surface area, carbides are used as adsorbents for various substances. For example, Patent Literature 1 describes a phosphorus recovery material using a carbide supporting calcium. By adsorbing phosphorus using such a phosphorus recovery material, water pollution due to discharge of phosphorus into natural waters can be suppressed. Further, when the phosphorus-collecting material having adsorbed phosphorus is buried in farmland, the phosphorus adsorbed on the phosphorus-collecting material is dissolved by the organic acid released from the root of the crop. That is, since this phosphorus functions as a fertilizer for agricultural products, it is possible to improve the yield of agricultural land in which the phosphorus recovery material is buried, or to grow high-quality agricultural products.

  In this way, it is not merely to improve the soil quality of the soil, for example, by adsorbing a certain harmful substance, a carbide that can suppress environmental pollution, or applying the harmful substance to other uses. The demand for possible carbides is increasing.

JP 2007-75706 A

  However, in the phosphorus recovery material of Patent Document 1, it is necessary to use a material containing a large amount of silicon, such as rice husk or diatomaceous earth. When a material containing a large amount of silicon is used, the production amount of the phosphorus recovery material is limited. In addition, there is a limit to the amount that can adsorb substances such as phosphorus.

  An embodiment of the present invention has been made in view of the above problems, and has as its object to provide a method for manufacturing an adsorbent that can manufacture an adsorbent using various materials.

  In the method for introducing particles into a porous material according to an embodiment of the present invention, a liquid containing nanoparticles including iron is permeated into pores of the porous material, and the liquid is dried.

The nanoparticles may include iron oxide and reduce the iron oxide after drying the liquid. It is known that iron oxide has a different composition, but divalent or trivalent iron may be used. That is, iron oxide (II) FeO or iron oxide (III) Fe ₂ O ₃ may be used.

  The pressure may be reduced while the porous material is immersed in the liquid.

  The nanoparticles in the liquid are separated based on the size of the nanoparticles, and the first dispersion in which the nanoparticles having a relatively small size are dispersed is permeated into the pores of the porous material. Subsequently, a second dispersion in which the nanoparticles having a relatively large size are dispersed may be impregnated into the pores of the porous material.

  In the method for introducing particles into a porous material according to an embodiment of the present invention, powdery nanoparticles are put into pores of the porous material.

  In a state where the porous material is submerged in the powdery nanoparticle, an airflow may be generated from outside the porous material toward the holes.

  The porous material may have conductivity.

  The porous material may be a carbide.

  The reduction of the iron oxide may be performed using a gas containing hydrogen, carbon monoxide, or a hydrocarbon.

  The reduction of the iron oxide may be performed at a temperature of 500 ° C. or more and 900 ° C. or less using a gas containing carbon monoxide.

  The reduction of the iron oxide may be performed at a temperature of 100 ° C. or more and 900 ° C. or less using a gas containing hydrogen.

  According to one embodiment of the present invention, it is possible to provide a method for manufacturing an adsorbent that can manufacture an adsorbent using various materials.

It is a flowchart which shows the manufacturing method of the adsorbent which concerns on one Embodiment of this invention. It is sectional drawing which shows the hole shape of the porous material used for the adsorbent which concerns on one Embodiment of this invention. It is a figure showing the manufacturing method of the adsorbent concerning one embodiment of the present invention. It is a figure showing the manufacturing method of the adsorbent concerning one embodiment of the present invention. It is a figure showing the manufacturing method of the adsorbent concerning one embodiment of the present invention. It is a flowchart which shows the manufacturing method of the adsorbent which concerns on one Embodiment of this invention. It is a flowchart which shows the manufacturing method of the adsorbent which concerns on one Embodiment of this invention. It is a figure showing the manufacturing method of the adsorbent concerning one embodiment of the present invention. It is a figure explaining the method of reducing the pressure of the porous material immersed in the aqueous solution in the manufacturing method of the adsorbent concerning one embodiment of the present invention.

  Hereinafter, an adsorbent and a method for manufacturing the adsorbent according to an embodiment of the present invention will be described with reference to the drawings. However, the adsorbent and the method for producing the adsorbent according to one embodiment of the present invention can be implemented in many different modes, and are not to be construed as being limited to the description of the following examples. Note that, in the drawings referred to in this embodiment, the same portions or portions having similar functions are denoted by the same reference numerals or the same reference numerals, and the description thereof is not repeated.

  In the following embodiments, as the porous material used for the adsorbent, a carbide obtained by carbonizing an organic substance will be exemplified, but the present invention is not limited to this configuration. For example, the porous material may be a porous member other than carbide. In addition, as long as there is no particular technical contradiction, techniques between different embodiments can be combined.

<First embodiment>
[Method of Manufacturing Adsorbent 10]
The adsorbent 10 according to the first embodiment and a method for manufacturing the adsorbent 10 will be described with reference to FIGS. In the present embodiment, as the porous material 100 used for the adsorbent 10 (see FIG. 5), a carbide obtained by carbonizing an organic substance is used, and iron oxide is used as metal nanoparticles introduced into the pores of the porous material 100. Is used to reduce the iron oxide attached to the pores of the porous material 100, so that zero-valent iron particles are arranged in the pores of the porous material 100.

  FIG. 1 is a flowchart showing a method for manufacturing an adsorbent according to one embodiment of the present invention. FIG. 2 is a cross-sectional view showing a pore shape of a porous material used for an adsorbent according to one embodiment of the present invention. 3 to 5 are diagrams illustrating a method of manufacturing an adsorbent according to one embodiment of the present invention.

  As shown in FIG. 1, the organic matter is carbonized in step S101. In the present embodiment, wood is used as the organic matter. Organic matter is carbonized by heat treatment in an atmosphere having an oxygen ratio lower than that in the air.

  There are mainly two types of carbonization furnaces. A carbonization furnace that supplies heat required for carbonization from the outside is called an external heating type, and a furnace that secures heat from materials is called an internal combustion type. The external heat type cuts off oxygen and carbonizes, while the internal combustion type supplies oxygen for combustion necessary to secure the minimum amount of heat required for carbonization. That is, basically, the process of heating at a high temperature under reducing conditions is called carbonization. When an organic substance is heated under reducing conditions, compositional decomposition in the organic substance starts during the temperature rise (for example, about 280 ° C.), and oxygen and hydrogen in the organic substance are converted into gases such as carbon dioxide, carbon monoxide, hydrogen, and hydrocarbons. And evolves into amorphous carbon with a high carbon content. By continuing to heat at a higher temperature, oxygen and hydrogen in the organic matter are further reduced, and a carbide composed of high-purity fixed carbon and ash is formed. Due to such a change, the organic matter is changed into carbide. Since water and constituents in the organic substance are eliminated as volatile gas and the like, and a certain amount of carbon remains, a large number and various small and large continuous pores are formed in the carbide formed by carbonization of the organic substance. The carbide formed by the progress of carbonization as the carbonization temperature increases has heat resistance (fire resistance), adsorptive properties, and conductive properties. A carbide formed by carbonization of an organic material is an example of the porous material 100. In this case, the porous material 100 has conductivity.

  Here, the pore shape of the porous material 100 when a carbide is used as the porous material 100 will be described with reference to FIG. As shown in FIG. 2, the porous material 100 has a macropore 200, a mesopore 210, and a micropore 220. The macro holes 200 are holes connected to the surface of the porous material 100. Inside the porous material 100, the macro holes 200 are subdivided to form mesopores 210, and the mesopores 210 are subdivided to form micropores 220. The size of the macropore 200 is approximately 50 nm to 40 μm. The size of the mesopores 210 is approximately 2 nm to 50 nm. The size of the micropores 220 is approximately 0.5 nm to 2 nm.

  As shown in FIG. 1, apart from the carbonization of the organic substance in step S101, dispersion of the nanoparticles 110 is performed in step S103. In the present embodiment, iron oxide particles are used as the nanoparticles 110. The dispersion in step S103 is realized by performing a dispersion treatment on the aggregate including the nanoparticles 110 in the liquid to form primary particles. When the nanoparticles 110 having a particle diameter of 100 nm or less are dispersed to the primary particles, the nanoparticles 110 are smaller than the visible light wavelength (about 400 to 700 nm), so that they do not scatter light and a transparent dispersion liquid 120 can be obtained. it can. However, the dispersion liquid 120 is merely an example of a liquid containing the nanoparticles 110, and a liquid other than the above may be used.

  In step S105, the carbide formed in step S101 is immersed in the dispersion 120 formed in step S103. The state at this time is shown in FIG. As shown in FIG. 3, when the dispersion liquid 120 is supplied to the porous material 100, the dispersion liquid 120 is filled with the pores of the porous material 100 (the macropores 200, the mesopores 210, and the micropores 220 (see FIG. 2)). Penetrate (penetrate). Accordingly, the nanoparticles 110 in the dispersion liquid 120 also enter the pores of the porous material 100. That is, by immersing the porous material 100 in the dispersion liquid 120, the nanoparticles 110 are permeated into the pores of the porous material 100. Here, the nanoparticles 110 are moved into the pores from the outside of the porous material 100 while maintaining the shape.

  Here, the mesopores 210 and the micropores 220 are much smaller in size than the macropores 200, and their ends are dead ends inside the porous material 100. For this reason, when the dispersion liquid 120 soaks into the pores of the porous material 100, for example, bubbles 130 may be generated at the tip of the micropore 220. In the example of FIG. 3, a state in which bubbles 130 are generated only at the tip of the micropore 220 is illustrated. However, the bubbles 130 may extend to the mesopores 210 or may extend to the macropores 200. Since the dispersion liquid 120 cannot penetrate into the region where the bubbles 130 exist, the nanoparticles 110 cannot be supplied to this region.

  In order to eliminate such a phenomenon, in step S107 of FIG. 1, while the porous material 100 is immersed in the dispersion liquid 120, the atmosphere in which these are arranged is reduced in pressure. The state at this time is shown in FIG. As shown in FIG. 4, in a state where the dispersion liquid 120 is supplied to the porous material 100 and the atmosphere in which these are disposed is decompressed, bubbles 130 existing at the tip of the micropore 220 as shown in FIG. Are diffused out of the hole. This process may be called degassing. When the bubbles 130 are diffused out of the holes as shown in FIG. 4, the dispersion liquid 120 can enter the position where the bubbles 130 existed in FIG. In this example, the nanoparticles 110 can be supplied to the micropores 220). In addition, when no air bubbles are generated inside the hole as described above, or even when air bubbles are generated inside the hole, as long as the presence of the air bubbles does not adversely affect the characteristics of the adsorbent 10, This step S107 and the next step S109 may be omitted.

  In step S109, the atmosphere decompressed in step S107 is returned to the atmospheric pressure, and drying in step S111 is performed. By this drying, the liquid contained in the dispersion liquid 120 is removed, and the nanoparticles 110 adhere to the pores of the porous material 100. This drying is performed while heating the porous material 100. When drying the porous material 100, the humidity of the environment in which the porous material 100 is arranged may be adjusted.

  FIG. 5 shows a state where the porous material 100 after being immersed in the dispersion liquid 120 is dried. As shown in FIG. 5, by removing the liquid contained in the dispersion liquid 120, the nanoparticles 110 contained in the dispersion liquid 120 adhere to the inside of the pores of the porous material 100 and to the surface thereof. Specifically, the nanoparticle 110 adheres to the inner wall of at least one of the macro hole 200, the meso hole 210, and the micro hole 220. In FIG. 5, the nanoparticles 110 are attached to the inner walls of all the holes. In steps S105 to S109, the dispersion liquid 120 can be supplied also to the mesopores 210 and the micropores 220, so that the nanoparticles 110 can be attached to the inner walls of these pores in step S111.

  In step S113 of FIG. 1, a reduction treatment of the nanoparticles 110 attached in the pores of the porous material 100 is performed. In other words, the nanoparticles 110 are reduced while being attached to the inner wall of at least one of the macropores 200, the mesopores 210, and the micropores 220. The reduction treatment is performed by a heat treatment in a reducing gas atmosphere. By this reduction treatment, iron oxide (divalent or trivalent iron) used as the nanoparticle 110 is reduced to zero-valent iron. Thus, the adsorbent 10 according to the present embodiment is manufactured. The zero-valent iron contained in the adsorbent 10 adsorbs phosphorus, arsenic, and the like.

  In addition, as organic substances used in step S101, living trees (including thinned wood, conifers, bamboos, and other thinned woods, and waste woods), sawmills or wood processing plants (sawdust, bark chips, chip chips, and trimmings) can be used. And woody wastes of plant shells, building demolition materials or furniture materials. The carbide generated in step S101 is, for example, charcoal or bamboo charcoal. Charcoal may include white charcoal, black charcoal, ogre charcoal, coconut shell charcoal, fir shell charcoal, and powdered charcoal, in addition to bamboo charcoal.

The carbonization temperature of the organic substance in step S101 is 400 ° C to 1200 ° C, 500 ° C to 1100 ° C, 600 ° C to 1000 ° C, or 700 ° C to 900 ° C. The organic carbonization atmosphere is an inert gas atmosphere such as a nitrogen gas or an argon gas, an oxygen-free atmosphere, a low oxygen atmosphere, a reducing atmosphere, or a reduced pressure atmosphere. When carbonization of an organic substance is performed in a reduced pressure atmosphere, a low vacuum state of 100 Pa or more and 10 ⁵ Pa or less, a medium vacuum state of 0.1 Pa or more and 100 Pa or less, a high vacuum state of 10 ^-5 Pa or more and 0.1 Pa or less, or 10 ^-5. It can be performed in an ultrahigh vacuum state of Pa or less. In the case where carbonization of an organic substance is performed in a low oxygen atmosphere, the oxygen concentration can be performed at 0.01% or more and 3% or less, or 0.1% or more and 1% or less. The carbonization time of the organic substance is from 10 minutes to 10 days, or from 10 minutes to 5 hours. The carbonization of organic matter is carried out by internal combustion or external heating, batch type open or closed type charcoal kiln, continuous rotary kiln or oscillating carbonization furnace, screw furnace, heating chamber, covered heat-resistant vessel (crucible ) Can be performed.

  In the present embodiment, the method of obtaining the porous material 100 by carbonizing the organic material in step S101 has been described, but a commercially available carbide may be used as the porous material 100.

The size of the nanoparticles 110 used in step S103 is 1 nm or more and 100 nm or less, 2 nm or more and 50 nm or less, or 3 nm or more and 30 nm or less. When iron oxide is used as the nanoparticles 110, the nanoparticles 110 include, for example, wustite (FeO), hematite (Fe ₂ O ₃ ) particles, or magnetite (Fe ₂ O ₄ ) particles. As the nanoparticles 110, an iron compound other than iron or iron oxide may be used. In addition, other than iron, aluminum, cerium, titanium, zinc, zirconia, silicon, chromium, vanadium, copper, nickel, cobalt, oxides thereof, and alloys thereof may be used as the nanoparticles 110.

  As the liquid of the dispersion liquid 120 used in step S103, water, ethanol, IPA (isopropyl alcohol), toluene, xylene, MIBK (methyl isobutyl ketone), butyl acetate, PEGMA (polyethylene glycol monomethacrylate), DMA (dimethylacetamide), Terpineol or butyl carbitol is used.

  As a method for dispersing the nanoparticles 110 in step S103, for example, a bead mill method, an ultrasonic homogenizer method, or a liquid jet mill method for rapidly stirring a packed layer of micro-spherical ceramic spheres is used. In the present embodiment, the method for producing the dispersion liquid 120 in step S103 has been described as an example, but a commercially available dispersion liquid 120 may be used.

  Further, a dispersant for promoting the dispersion of the nanoparticles 110 may be added to the dispersion liquid 120. As the dispersant, for example, a surfactant can be used. Use of anionic (anionic) surfactants, cationic (cationic) surfactants, amphoteric (zwitterionic) surfactants, nonionic (nonionic) surfactants, and polymer surfactants as surfactants Can be. As the anionic surfactant, sodium fatty acid, monoalkyl sulfate, alkyl polyoxyethylene sulfate, alkylbenzene sulfonate, alkyl ether sulfate, alkylethanol triethanolamine, and alkylbenzene sulfonate can be used. Alkyl trimethyl ammonium salt, dialkyl dimethyl ammonium chloride, alkyl pyridium chloride, and alkyl benzyl dimethyl ammonium salt can be used as the cationic surfactant. As the amphoteric surfactant, alkyldimethylamine oxide and alkylcarboxybetaine can be used. As a nonionic surfactant, polyoxyethylene alkyl ether, fatty acid sorbitan ester, alkyl polyglucoside, fatty acid diethanolamide, octylphenol ethoxylate, and alkyl monoglyceryl ether can be used. As a polymer surfactant, polyacrylate, polystyrene sulfonate, polyvinyl alcohol, and polyethyleneimine can be used. The concentration of the dispersant is from 0.01% to 20%, or from 0.01% to 1%. In addition, since the carbide has hydrophobicity (non-hydrophilicity) unless carbonized at a high temperature, water hardly enters the inside. Therefore, by including a surfactant in the dispersion liquid 120, the dispersion liquid 120 can be easily permeated into the porous material 100.

  In step S105, the above-described surfactant may be supplied to the porous material 100 before the porous material 100 is immersed in the dispersion liquid 120. The supply of the surfactant may be performed by applying the surfactant on the upper surface of the porous material 100, or may be performed by immersing the porous material 100 in a liquid containing a surfactant. Further, similarly to step S107, deaeration may be performed in a state where the surfactant is supplied to the porous material 100.

  Further, the porous material 100 does not have to be immersed in the dispersion liquid 120. For example, by applying the dispersion liquid 120 to the surface of the porous material 100, the dispersion liquid 120 may be permeated into the pores of the porous material 100.

  In step S107, vibration may be applied at the time of degassing in order to more efficiently diffuse the bubbles 130 out of the holes. This vibration may be an ultrasonic vibration. Further, the porous material 100 may be heated at the time of degassing. Further, at the time of degassing, the porous material 100 may be tilted or rotated in the dispersion liquid 120. The pressure at the time of deaeration is usually -0.101 MPa or more and -0.03 MPa or less as a gauge pressure with the atmospheric pressure being zero, and the deaeration time is 10 seconds or more and 1 hour or less, or 30 seconds or more and 10 minutes or less.

  When a carbide is used as the porous material 100, the dispersion 120 containing the nanoparticles 110 may not easily permeate into the pores of the porous material 100 because the carbide is hydrophobic. In such a case, most of the porous material 100 floats on the liquid surface due to air existing in the holes (the macro holes 200, the meso holes 210, and the micro holes 220) of the porous material 100. Even in such a state, by reducing the pressure, the air existing in the holes can be drawn out of the porous material 100 and discharged out of the dispersion liquid 120. Thereby, in the pores of the porous material 100, the region where the bubbles 130 existed can be filled with the dispersion liquid 120 containing the nanoparticles 110.

  When the pressure is reduced as described above, the bubbles 130 in the porous material 100 increase, the buoyancy of the porous material 100 increases, and the porous material 100 may float on the liquid surface. In order to suppress this phenomenon, a mesh-shaped floating prevention plate smaller than the porous material 100 may be provided in the container containing the dispersion liquid 120. If the porous material 100 rises to the surface of the liquid, the efficiency of replacement between the bubbles 130 and the dispersion 120 on the surface of the liquid deteriorates, and when returning to atmospheric pressure, air instead of the dispersion 120 becomes porous. There is a possibility of entering the material 100. However, such a phenomenon can be suppressed by installing the floating prevention plate as described above.

  The steps S105 to S111 described above may be repeatedly performed a plurality of times. Further, the steps S107 and S109 may be repeatedly performed a plurality of times. By repeating the above steps a plurality of times, the amount of the nanoparticles 110 attached to the porous material 100 can be increased. Alternatively, the drying in step S111 may be performed while the pressure is reduced without passing through the step of returning to the atmospheric pressure in step S109. In this case, the pressure may be returned to the atmospheric pressure after the drying, or the reduction in step S113 may be performed while the pressure is reduced. Further, the above drying and reduction may be performed in the same step.

  The reduction temperature of the nanoparticles 110 in step S113 is from 500 ° C to 1200 ° C, from 500 ° C to 1000 ° C, from 500 ° C to 900 ° C, or from 700 ° C to 900 ° C. The reducing gas used for the reduction treatment of the nanoparticles 110 is a carbon monoxide gas, a hydrogen gas, a hydrogen sulfide gas, a sulfur dioxide gas, or a hydrocarbon gas. Further, a reducing gas may be mixed such as a mixture of carbon monoxide and hydrogen. Further, since many reducing gases are difficult to handle from the viewpoint of explosiveness and flammability, they may be diluted with an inert gas. For example, it can be diluted with nitrogen gas so that the concentration of carbon monoxide is 1% to 20% (that is, the concentration of nitrogen is 99% to 80%). The reduction time is 1 minute or more and 10 hours or less, 10 minutes or more and 2 hours or less. The reduction may be either a batch type or a continuous type, and a tube furnace or a box furnace is appropriately used as long as it can heat and introduce a reducing gas (may be mixed with an inert gas). be able to. When a carbon monoxide gas is used as the reducing gas, the reduction temperature can be 500 ° C to 1200 ° C, 500 ° C to 1000 ° C, 500 ° C to 900 ° C, or 700 ° C to 900 ° C. When a hydrogen gas is used as the reducing gas, the reduction temperature can be 100 ° C to 1200 ° C, 100 ° C to 900 ° C, or 700 ° C to 900 ° C.

  When the nanoparticles 110 are reduced, carbon dioxide gas, oxygen gas, and water vapor are added to the reducing gas and activated to activate, thereby increasing the number of fine pores in the porous material 100 simultaneously with the reduction (active carbonization). )be able to. Activated carbonization of the porous material 100 can increase the surface area of the porous material 100.

  When a material that does not need to be reduced, such as zero-valent iron, is used as the nanoparticle 110, the reduction process in step S113 can be omitted.

  Conventionally, when a metal crystal is formed inside a carbide, carbonization has been performed after immersing a dried organic substance before carbonization in a solution in which the metal compound is dissolved and drying the organic substance. Since the above-mentioned macro hole 200 is a hole caused by a tree tracheid hole, it is considered that a metal crystal is deposited on the inner wall of the macro hole 200. In addition, when raw organic matter such as raw wood is dried and immersed in a solution in which the metal compound is dissolved, the metal compound can be immersed into the biomass by diffusion and infiltration. There is a possibility that metal crystals are not sufficiently precipitated on the surface of the pores.

  In contrast, in the present embodiment, after the mesopores 210 and the micropores 220 are formed in the porous material 100, the dispersion liquid 120 containing the nanoparticles 110 is permeated into the pores of the porous material 100 and dried. Therefore, the nanoparticles 110 can be attached to the inner walls of these holes.

  Conventionally, the above-described metal oxide particles are reduced by heat treatment for carbonizing an organic substance by utilizing carbon monoxide and hydrogen generated during carbonization. Therefore, the conditions for carbonization and the conditions for reduction treatment could not be individually controlled. For example, it has been difficult to adjust the amount of reducing gas required for reducing metal oxide particles.

  On the other hand, in the present embodiment, since the reduction is performed by a heat treatment different from carbonization, conditions suitable for the reduction can be appropriately selected. For example, the carbonization and the reduction treatment can be performed by different apparatuses. Alternatively, the carbonization temperature and the reduction temperature can be treated at different temperatures and times. Alternatively, the carbonization and the reduction treatment can be performed in different atmospheres.

  In the present embodiment, a configuration in which a carbide obtained by carbonizing an organic substance is used as the porous material 100 is illustrated, but a material other than the carbide may be used as the porous material 100. Further, the configuration in which the porous material 100 is obtained by carbonizing wood as an organic substance has been illustrated, but an organic substance other than wood may be carbonized.

  When the porous material 100 is a carbide, since the carbide has high conductivity, electron exchange is rapidly performed between the carbide and the zero-valent iron crystal particles attached to the pores. Therefore, when a carbide containing crystal particles of zero-valent iron is put into water, zero-valent metal iron is quickly ionized on the surface of the porous body, and a hydroxide such as iron oxyhydroxide (FeOOH) is generated. It reacts with phosphate ions present in water to form iron phosphate and can be adsorbed and fixed on carbides. As described above, by using a conductive material as the porous material 100, phosphorus can be efficiently adsorbed.

<Second embodiment>
[Production method of adsorbent 10A]
A method for manufacturing the adsorbent 10A according to the second embodiment will be described with reference to FIG. The method for producing the adsorbent 10A is similar to the method for producing the adsorbent 10 according to the first embodiment shown in FIG. 1, but the nanoparticles 110A dispersed in the dispersion 120A are separated by size and separated. The method differs from the method for manufacturing the adsorbent 10 of the first embodiment in that the nanoparticles 110A are attached to the pores of the porous material 100A in different steps depending on the size. In the following description of FIG. 6, description of portions common to FIG. 1 will be omitted, and different points from FIG. 1 will be mainly described. Note that the configuration of the adsorbent 10A according to the present embodiment is the same as the configuration of the adsorbent 10 according to the first embodiment, and is not illustrated here. In the following description, among the configurations of the adsorbent 10A, the same components as those of the adsorbent 10 are denoted by the same reference numerals as those used in the adsorbent 10, and the letters “A” are appended thereto, and the description thereof is omitted. .

  As shown in FIG. 6, after forming the dispersion liquid 120A in which the nanoparticles 110A are dispersed in Step S103A, separation based on the size of the nanoparticles 110A is performed in Step S115A. Specifically, based on the sedimentation velocity of the nanoparticles 110A in the dispersion 120A, separation of the nanoparticles 110A by size is performed. Here, the nanoparticle 110A can be separated using a centrifugal sedimentation method using centrifugal force. By this separation, the dispersion 120A is divided into a first dispersion in which the relatively small nanoparticles 110A are dispersed and a second dispersion in which the relatively large nanoparticles 110A are dispersed.

  The nanoparticles 110A dispersed in the first dispersion have a first particle size distribution, and the nanoparticles 110A dispersed in the second dispersion have a second particle size distribution. The first particle size distribution and the second particle size distribution may be distributions in which the sizes do not overlap with each other, or may be distributions in which a part of each particle size is overlapped. That is, the size of the nanoparticles 110A contained in the first dispersion and the size of the nanoparticles 110A contained in the second dispersion may be completely different, and are common to the first dispersion and the second dispersion. May be included.

  In step S117A, the porous material 100A carbonized in step S101A is immersed in the first dispersion liquid formed in step S115A. That is, the first dispersion including the relatively small nanoparticles 110A is impregnated into the pores of the porous material 100A. Thereafter, as in steps S107 to S111 of FIG. 1, degassing and drying are performed to attach the nanoparticles 110A to the pores of the porous material 100A (steps S107A-1, S109A-1, S111A). -1).

  Next, in step S119A, the porous material 100A having the relatively small-sized nanoparticles 110A attached in the holes is immersed in the second dispersion liquid formed in step S115A. That is, the second dispersion including the relatively large nanoparticles 110A is impregnated into the pores of the porous material 100A. Thereafter, degassing and drying are performed in the same manner as in steps S107 to S111 in FIG. 1, so that the pores of the porous material 100A to which the relatively small nanoparticles 110A have already adhered in step S111A-1 are formed. The nanoparticle 110A having a relatively large size is attached (steps S107A-2, S109A-2, S111A-2).

  When the dispersion liquid containing the nanoparticles 110A of various sizes is infiltrated into the pores of the porous material 100A, if the relatively large nanoparticles 110A block the mesopores 210A, the nanoparticles 110A will It is impossible to enter the micro-hole 220A existing further on the tip side of the hole 210A. However, as described above, by attaching the relatively small nanoparticles 110A into the pores of the porous material 100A, such a problem can be suppressed.

  The above steps S117A to S111A-1 may be repeated a plurality of times. Further, the above steps S119A to S111A-2 may be repeatedly performed a plurality of times.

  As described above, according to the method for manufacturing the adsorbent 10A according to the present embodiment, the nanoparticles 110A can be attached to details such as the micropores 220A. As a result, it is possible to manufacture the adsorbent 10A having a high adsorption efficiency for a substance such as phosphorus.

<Third embodiment>
[Production method of adsorbent 10B]
A method of manufacturing the adsorbent 10B according to the third embodiment will be described with reference to FIGS. The method for producing the adsorbent 10B is similar to the method for producing the adsorbent 10 according to the first embodiment shown in FIG. 1, but instead of dispersing the nanoparticles 110B in a liquid, the powder nanoparticles 190B are removed. The method is different from the method of manufacturing the adsorbent 10 of the first embodiment in that the adsorbent 10 is inserted into the holes of the porous material 100B. In the following description of FIG. 7, a description of parts common to FIG. 1 will be omitted, and points different from FIG. 1 will be mainly described. Note that the configuration of the adsorbent 10B according to the present embodiment is the same as the configuration of the adsorbent 10 according to the first embodiment, and is not illustrated here. In the following description, among the configurations of the adsorbent 10B, the same components as those of the adsorbent 10 are denoted by the same reference numerals as those used in the adsorbent 10, and the alphabet "B" is appended to the same reference numeral, and the description thereof will be omitted. .

  As shown in FIG. 7, the porous material 100B carbonized in step S101B is immersed in the powdery nanoparticles 190B in step S121B. FIG. 8 shows the state at this time. As shown in FIG. 8, the powdery nanoparticle 190B is put in the container 300B, and the porous material 100B is submerged in the powdery nanoparticle 190B. FIG. 8 illustrates a configuration in which the porous material 100B is completely sunk in the powdery nanoparticles 190B, but the configuration is not limited to this. The powdery nanoparticle 190B only needs to be present at least near the opening end of the macropore 200B provided in the porous material 100B.

  When the atmosphere in which the porous material 100B is settled in the powdery nanoparticle 190B as described above is reduced in pressure (step S107B), the porous material 100B exists in the macropore 200B, the mesopore 210B, and the micropore 220B. The trapped air or gas diffuses out of these holes. Then, when the atmosphere is returned to the atmospheric pressure (step S109B), an air flow (air or gas flow) from the outside of the porous material 100B to the above-described hole is generated, and the air flow is generated near the opening end of the macro hole 200B. The powdery nanoparticles 190B move into the holes. In this way, the powdery nanoparticles 190B can be put into the holes.

  In the above description, the method of depressurizing the atmosphere in a state where the porous material 100B is submerged in the powdery nanoparticle 190B is exemplified, but the method is not limited to this method. For example, the porous material 100B may be submerged in the powdery nanoparticle 190B under a reduced pressure atmosphere, and then returned to the atmospheric pressure. Further, a gas containing powdery nanoparticles 190B may be sprayed toward the porous material 100B. Alternatively, even without generating an airflow from the outside of the porous material 100B toward the above-described hole, the vibration is applied while the porous material 100B is immersed in the powdery nanoparticle 190B, thereby obtaining the powdery nanoparticle 190B. May be moved into the above hole.

  The above steps S107B to S111B may be repeatedly performed a plurality of times. At this time, when the pressure is reduced in step S107B, the powdery nanoparticle 190B is prevented from coming out of the hole, and when returning to the atmospheric pressure in step S109B, the powder outside the porous material 100B is reduced. In order to make it easier for the nano-particles 190B to enter the holes, the speed of returning to the atmospheric pressure may be faster than the speed of the pressure reduction. Alternatively, in step S109B, the pressure may be increased to a pressure higher than the atmospheric pressure.

  As described above, according to the method for manufacturing the adsorbent 10B according to the present embodiment, the powdery nanoparticles 190B can be used to form the porous material 100B without using a dispersion liquid as in the first embodiment and the second embodiment. Can be placed in the hole.

  In the above embodiment, a specific method of depressurizing the porous material 100 (or 100A, 100B) in a state of being immersed in the dispersion liquid 120 (or 120A) or in a state of being immersed in the powdery nanoparticle 190B Will be described with reference to FIG. FIG. 9 is a diagram illustrating a method of reducing the pressure of a porous material immersed in an aqueous solution in the method for producing an adsorbent according to one embodiment of the present invention.

  As shown in FIG. 9, the decompression container 400 has a container portion 401 and a lid portion 403. The container section 401 has a shape capable of storing the dispersion liquid 120 (or the powdery nanoparticles 190B). The lid 403 is provided on the upper part of the container 401 so as to be detachable. The cover 403 is provided with an exhaust port 405 and an air supply port 407. The exhaust port 405 is connected to the first valve 410. The first valve 410 is connected to a vacuum pump 430. The air supply port 407 is connected to the second valve 420. The second valve 420 is connected to a pipe 435 that supplies air or a desired gas from the outside into the decompression container 400. Further, a vacuum pressure gauge 440 is connected to the decompression container 400. The vacuum pressure gauge 440 can measure the pressure inside the decompression container 400. Note that an aspirator may be used instead of the vacuum pump 430.

  As shown in FIG. 9, the dispersion 120 (or the powdery nanoparticle 190 </ b> B) is supplied to the decompression container 400, and the porous material 100 is immersed in the dispersion 120. The case 500 containing the porous material 100 therein is submerged in the dispersion liquid 120. The case 500 has a shape surrounding the internal space, and is submerged in the dispersion liquid 120 with the porous material 100 stored in the internal space. That is, the case 500 can prevent the porous material 100 from rising and rising above the liquid surface of the dispersion liquid 120, and can lift the porous material 100 when removing the case 500 from the decompression container 400.

  The case 500 is provided with an opening large enough to allow the dispersion liquid 120 to pass therethrough and large enough to prevent the porous material 100 from passing therethrough. The size of the opening is, for example, 0.1 mm or more and 50 mm or less. As the case 500, a mesh basket made of metal such as stainless steel or resin such as hard plastic can be used. Although the case 500 exemplifies a configuration in which the case 500 surrounds the upper, lower, left, and right sides of the porous material 100, the configuration is not limited to this. For example, the case 500 may have a shape in which the upper portion of the porous material 100 is covered and the lower portion is removed so as to suppress the porous material 100 from rising upward. Alternatively, the case 500 has a shape provided above the porous member 100 and below the porous member 100 so that the porous member 100 can be lifted when the case 500 is taken out of the decompression container 400. Is also good.

  By operating the vacuum pump 430 with the first valve 410 opened and the second valve 420 closed, the pressure inside the decompression container 400 is reduced. Thereafter, by supplying air or a desired gas to the pipe 435 with the first valve 410 closed and the second valve 420 opened, the inside of the decompression container 400 can be returned to the atmospheric pressure.

  After the above processing is completed, the lid 403 is opened, and the case 500 is taken out together with the porous material 100. At this time, since the above-mentioned opening is provided in a part of the case 500 corresponding to the lower part of the porous material 100, it is possible to take out the porous material 100 while dropping the excessive dispersion liquid 120 into the decompression container 400. it can.

  As described above, one embodiment of the present invention has been described with reference to the drawings. However, the present invention is not limited to the above embodiment, and can be appropriately changed without departing from the spirit of the present invention. For example, those in which a person skilled in the art appropriately adds, deletes, or changes the design based on the adsorbent of the present embodiment are also included in the scope of the present invention as long as they have the gist of the present invention. Furthermore, the above-described embodiments can be appropriately combined with each other as long as there is no inconsistency, and technical matters common to the embodiments are included in each embodiment without explicit description.

  Regarding other effects different from the effects obtained by the aspects of the above-described embodiments, those that are obvious from the description in this specification or that can be easily predicted by those skilled in the art are, of course, It is understood that the present invention brings about.

10: adsorbent, 100: porous material, 110: nanoparticles, 120: dispersion, 130: air bubbles, 190B: powdered nanoparticles, 200: macropore, 210: mesopore, 220: micropore, 300B: container , 400: decompression container, 410: container portion, 403: lid portion, 405: exhaust port, 407: air supply port, 410: first valve, 420: second valve, 430: vacuum pump, 435: piping, 440: Vacuum pressure gauge, 500: case

Claims (11)

Infiltrate the liquid containing the iron-containing nanoparticles into the pores of the porous material,
A method for producing an adsorbent, wherein the liquid is dried. The nanoparticles include iron oxide,
The method for producing an adsorbent according to claim 1, wherein the iron oxide is reduced after drying the liquid.   The method for producing an adsorbent according to claim 1, wherein the pressure is reduced while the porous material is immersed in the liquid. Separating the nanoparticles in the liquid based on the size of the nanoparticles,
Impregnating the first dispersion in which the nanoparticles of a relatively small size are dispersed into the pores of the porous material,
4. The method according to claim 1, wherein the second dispersion in which the nanoparticles having a relatively large size are dispersed is impregnated into the pores of the porous material. 5. Method.   A method for producing an adsorbent, wherein powdery nano-particles are put into pores of a porous material.   The method for producing an adsorbent according to claim 5, wherein an airflow is generated from outside the porous material toward the holes while the porous material is submerged in the powdery nanoparticles.   The method for producing an adsorbent according to any one of claims 1 to 6, wherein the porous material has conductivity.   The method for producing an adsorbent according to any one of claims 1 to 7, wherein the porous material is a carbide.   The method for producing an adsorbent according to claim 2, wherein the reduction of the iron oxide is performed using a gas containing hydrogen, carbon monoxide, or a hydrocarbon.   The method for producing an adsorbent according to claim 2, wherein the reduction of the iron oxide is performed at a temperature of 500C to 900C using a gas containing carbon monoxide. The method for producing an adsorbent according to claim 2, wherein the reduction of the iron oxide is performed at a temperature of 100C to 900C using a gas containing hydrogen.

Images