WO2020031516A1

WO2020031516A1 - Method of manufacturing adsorbent

Info

Publication number: WO2020031516A1
Application number: PCT/JP2019/024319
Authority: WO
Inventors: 昭太袋; 響倉澤; 久保田　洋
Original assignee: 株式会社フジタ
Priority date: 2018-08-10
Filing date: 2019-06-19
Publication date: 2020-02-13
Also published as: JP7177840B2; JPWO2020031516A1

Abstract

This method of manufacturing an adsorbent includes forming a carbide by carbonizing an organic substance, causing a solution comprising iron to seep into pores of the carbide, and drying the carbide into which the solution has seeped. The solution may comprise iron ion. Iron compounds adhered to inner walls of the pores of the carbide by drying the carbide may be reduced. An alkaline solution may be caused to seep into the holes of the dried carbide and iron hydroxide generated by the alkaline solution may be reduced. The solution may comprise iron ion, and may be a colloidal solution comprising particles comprising iron hydroxide.

Description

Adsorbent manufacturing method

The present invention relates to a method for producing an adsorbent. In particular, the present invention relates to a method for producing an adsorbent that adsorbs phosphorus and arsenic.

技術 In order to reduce the amount of carbon dioxide in the atmosphere, there is known a technology for artificially capturing and storing carbon dioxide in the ground. For example, it is possible to absorb carbon dioxide in the atmosphere using biomass such as trees and 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 rot and decompose, and will release carbon dioxide into the atmosphere again. On the other hand, when biomass is heated in a state where oxygen is cut off, oxygen atoms and hydrogen atoms are desorbed, and carbides 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 carbide has a very large surface area because it is porous. 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.

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

The method for producing an adsorbent according to one embodiment of the present invention includes the steps of carbonizing an organic substance to form a carbide, impregnating a solution containing iron into pores of the carbide, and impregnating the solution containing iron. And drying the carbide.

The solution may contain iron ions.

The solution may be a colloid containing particles containing iron hydroxide.

The solution may contain heme iron.

(4) The alkali solution may be impregnated into the holes of the dried carbide to generate iron hydroxide particles, and the alkali solution may be discharged out of the holes of the carbide to dry the carbide.

The method for producing an adsorbent according to one embodiment of the present invention includes the steps of: forming a carbide by carbonizing an organic substance; Impregnated with the alkaline solution into the pores of the carbide impregnated with the solution to generate iron hydroxide particles, discharge the anion and the alkaline solution out of the pores, and dry the carbide. .

The iron hydroxide particles may be reduced.

炭化 The carbide impregnated with the solution containing iron may be dried, an iron compound may be attached to the carbide, and iron contained in the iron compound may be reduced.

減圧 The pressure may be reduced while the carbide is immersed in the solution.

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

還元 The reduction may be performed at a temperature of 500 ° C. or higher using a gas containing carbon monoxide.

還元 The reduction may be performed at a temperature of 100 ° C. or higher using a gas containing hydrogen.

According to one embodiment of the present invention, it is possible to provide a method of 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. FIG. 3 is a conceptual diagram showing a specific method for producing iron hydroxide in the adsorbent according to 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. FIG. 3 is a conceptual diagram showing a specific method for producing iron hydroxide in the adsorbent according to one embodiment of the present invention. 1 is a flowchart illustrating a method for producing a solution containing iron according to an embodiment of the present invention. It is a figure explaining the method of reducing the pressure of the porous material immersed in the solution in the manufacturing method of the adsorbent concerning one embodiment of the present invention.

Hereinafter, an adsorbent and a method for producing 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.

では In the following embodiment, as the porous material used for the adsorbent, a carbonized material of wood is exemplified, but the porous material is not limited to this configuration. For example, the carbide may be one obtained by carbonizing an organic substance other than wood. Further, 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. As a method for introducing metal particles into pores of the carbide, a solution containing iron is used. The following describes a configuration in which a method of dipping a carbide into the pores is used, and the iron compound attached to the pores of the carbide is reduced so that zero-valent iron particles are arranged in the pores of the carbide.

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 for manufacturing an adsorbent according to one embodiment of the present invention.

有機 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 fixed carbon and ash with high purity 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 or less.

As shown in FIG. 1, a solution 120 containing iron or an iron compound is prepared in step S103, separately from the carbonization of the organic substance in step S101. In the present embodiment, an aqueous solution containing iron is used as the solution 120. Specifically, as the solution 120, an aqueous ferrous chloride solution (FeCl ₂ ), an aqueous ferric chloride solution (FeCl ₃ ), and an aqueous ferrous nitrate solution (Fe (NO ₃ )) in which inorganic iron or an inorganic iron compound is dissolved. ₂ ), ferric nitrate aqueous solution (Fe (NO ₃ ) ₃ ), ferrous sulfate aqueous solution (FeSO ₄ ), ferric sulfate aqueous solution (Fe (SO ₄ ) ₃ ), or ferric polysulfate solution ([ Fe ₂ (OH) _n (SO ₄ ) _{3-n / 2} ] _m , provided that 0 <n ≦ 2, m = f (n)). Alternatively, a solution in which heme iron bound to a protein as an organic iron compound is dissolved can be used as the solution 120. Waste such as animal blood containing heme iron may be used. When these solutions are not particularly distinguished, they may be simply referred to as iron solutions. The solution 120 is not limited to the above-mentioned iron solution, and may be a solution containing iron other than the above. The solvent of the solution is not limited to water, but may be an organic solvent such as methanol, ethanol, phenol, benzene, and hexane.

In step S105, the carbide formed in step S101 is immersed in the solution 120 formed in step S103. The state at this time is shown in FIG. As shown in FIG. 3, when the solution 120 is supplied to the porous material 100, the solution 120 enters the pores (the macropores 200, the mesopores 210, and the micropores 220 (see FIG. 2)) of the porous material 100. I do (penetrate). Along with this, the iron ions 110 in the solution 120 also enter the pores of the porous material 100. That is, immersing the porous material 100 in the solution 120 causes the iron ions 110 to permeate into the pores of the porous material 100.

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 solution 120 permeates into the pores of the porous material 100, for example, bubbles 130 may be generated at the tips of the micropores 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 solution 120 cannot penetrate into the region where the bubbles 130 exist, the iron ions 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 solution 120, the pressure in the atmosphere in which these are arranged is reduced. The state at this time is shown in FIG. As shown in FIG. 4, when the atmosphere in which the solutions 120 are supplied is reduced in a state where the solutions 120 are supplied to the porous material 100, bubbles 130 existing at the tips of the micropores 220 as shown in FIG. Spread 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 solution 120 can enter the position where the bubbles 130 existed in FIG. In an example, the micropores 220) can be supplied with iron ions 110. 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, the porous material 100 is taken out of the solution 120, and the porous material 100 impregnated with the solution 120 is dried in step S111. The liquid contained in the solution 120 is removed by this drying. 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. This drying may be performed simultaneously with the heat treatment of the reduction process in the next step.

FIG. 5 shows a state where the porous material 100 is dried after being immersed in the solution 120. As shown in FIG. 5, by removing the solvent contained in the solution 120, the iron ions 110 contained in the solution 120 are precipitated, and the iron compound 111 is formed. Then, the iron compound 111 adheres in the pores of the porous material 100 and on the surface thereof. Specifically, the iron compound 111 adheres to the inner wall of at least one of the macropore 200, the mesopore 210, and the micropore 220. In FIG. 5, the iron compound 111 is attached to the inner walls of all these holes. In steps S105 to S109, since the solution 120 can be supplied also to the mesopores 210 and the micropores 220, the iron compound 111 can be attached to the inner walls of these pores in step S111.

{Circle around (1)} In step S113 in FIG. 1, a reduction treatment of the iron compound 111 attached to the inside of the pores of the porous material 100 and to the surface thereof is performed. In other words, the iron compound 111 is 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, the divalent or trivalent iron compound 111 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.

炭化 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 substance carbonization atmosphere is an inert gas atmosphere such as a nitrogen gas or an argon gas, an oxygen-free 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 −101200 Pa or more and −1300 Pa or less, a medium vacuum state of −101299.9 Pa or more and −101200 Pa or less, and a pressure of −101299.99999 Pa or more are usually obtained at a gauge pressure of zero atmospheric pressure. It can be performed in a high vacuum state of -101299.9 Pa or an ultra-high vacuum state of -101299.9999 Pa or less. The carbonization time of the organic material is 10 minutes or more and 10 days or less, 10 minutes or more and 5 hours 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. Organic matter is carbonized by internal combustion or external heating, batch-type open and closed charcoal kilns, continuous rotary kilns and oscillating carbonization furnaces, screw furnaces, heating chambers, and heat-resistant containers (crucibles) with lids. ) 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 as an example, but a commercially available carbide may be used as the porous material 100.

鉄 The mass percent concentration of iron contained in the solution 120 used in step S103 is 0.1 wt% or more and 50 wt% or less, 1 wt% or more and 40 wt% or less, or 5 wt% or more and 15 wt% or less. The time during which the porous material 100 is immersed in the solution 120 in step S103 is from 10 seconds to 24 hours, from 1 minute to 5 hours, or from 5 minutes to 1 hour. When the pressure is reduced after the carbide is immersed in a pressure vessel, the gauge pressure is usually -0.101 MPa or more and -0.02 MPa or less, -0.101 MPa or more and -0.04 MPa or less, or -0.101 MPa at a gauge pressure where the atmospheric pressure is zero. At least -0.08 MPa. In this case, the reduced pressure immersion time may be shorter than usual, and may be appropriately selected from 1 second to 1 hour, 10 seconds to 10 minutes, or 30 seconds to 5 minutes after reaching the predetermined gauge pressure. Good.

有機 As a solvent of the solution 120 used in step S103, an organic solvent such as water, methanol, ethanol, phenol, benzene, or hexane is used. In the present embodiment, the method of preparing the solution 120 in step S103 has been described as an example, but a commercially available solution may be used as the solution 120.

分散 A dispersant that promotes dispersion of the iron ions 110 may be added to the solution 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 the 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 adding a surfactant to the solution 120, the solution 120 can be easily permeated into the porous material 100.

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

(4) The porous material 100 does not have to be immersed in the solution 120. For example, by applying the solution 120 to the surface of the porous material 100, the solution 120 may be permeated into the pores of the porous material 100.

In step S107, vibration may be applied at the time of degassing 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 solution 120. The pressure at the time of deaeration is usually -0.101 MPa to -0.03 Mpa at a gauge pressure with the atmospheric pressure set to zero, and the deaeration time is 10 seconds to 1 hour, or 30 seconds to 10 minutes. .

When a carbide is used as the porous material 100, the solution 120 containing the iron ions 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 present in the holes can be drawn out of the porous material 100 and discharged out of the solution 120. Thereby, the solution 120 containing the iron ions 110 can be filled in the region where the bubbles 130 existed in the pores of the porous material 100.

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 solution 120. If the porous material 100 floats above the liquid surface, the efficiency of replacement between the bubbles 130 and the solution 120 on the liquid surface deteriorates, and when returning to the atmospheric pressure, air instead of the solution 120 is used instead of the porous material 100. Could get inside. However, such a phenomenon can be suppressed by installing the floating prevention plate as described above.

工程 The above steps S105 to S111 may be repeated a plurality of times. Further, the steps S107 and S109 may be repeatedly performed a plurality of times. 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. By repeating the above steps a plurality of times, the amount of the iron compound 111 attached to the porous material 100 can be increased.

還元 The reduction temperature of the iron compound 111 in step S113 may be at least 500 ° C. or higher. The range of the reduction temperature is, for example, 500 ° C to 1200 ° C, 500 ° C to 1000 ° C, 500 ° C to 900 ° C, or 700 ° C to 900 ° C. The reducing gas used for the reduction treatment of the iron compound 111 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 may be appropriately used as long as the structure allows heating and introduction of a reducing gas (may be mixed with an inert gas). it can. When a carbon monoxide gas is used as the reducing gas, the reduction temperature may be at least 500 ° C. or higher. In this case, the range of the reduction temperature can be, for example, 500 ° C to 1200 ° C, 500 ° C to 1000 ° C, 500 ° C to 900 ° C, or 700 ° C to 900 ° C. When hydrogen gas is used as the reducing gas, the reduction temperature may be at least 100 ° C. or higher. In this case, the range of the reduction temperature can be, for example, 100 ° C to 1200 ° C, 100 ° C to 900 ° C, or 700 ° C to 900 ° C.

When the iron compound 111 is 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.

Conventionally, when an iron compound is formed inside a carbide, the dried organic material before carbonization is immersed in a solution in which the iron compound is dissolved, dried, and then carbonized. Since the macro hole 200 is a hole caused by a tree tracheid hole, it is considered that reduced zero-valent iron crystals are deposited on the inner wall of the macro hole 200. In addition, when a raw organic material such as a raw wood is dried and immersed in a solution in which the iron compound is dissolved, the iron compound can be immersed into the organic material by diffusion and infiltration. There is a possibility that zero-valent iron crystals are not sufficiently precipitated on the surface of the pores.

On the other hand, in the present embodiment, after the mesopores 210 and the micropores 220 are formed in the porous material 100, the solution 120 containing iron is impregnated into the pores of the porous material 100 and dried. The iron compound 111 can be attached to the inner walls of these holes, and after reduction, zero-valent iron crystals can be attached to the inner walls of these holes.

従来 Also, conventionally, in a heat treatment for carbonizing an organic substance, the above-described iron compound has been reduced using carbon monoxide or 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 the reduction of iron compounds.

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. Here, when performing a reduction treatment of iron in an inert gas atmosphere or an oxygen-free atmosphere, a counter ion of the metal compound of the metal compound in the carbide reacts with the carbon constituting the carbide by heating, and carbon monoxide or hydrogen is reduced. Generated. For example, in the case of a carbide containing iron sulfate, sulfur dioxide gas generated by heating reacts with carbon in the carbide to generate carbon monoxide and sulfur dioxide. Alternatively, oxygen in the carbide reacts with carbon constituting the carbide to generate carbon monoxide. Alternatively, hydrogen contained in the carbide is thermally decomposed to produce methane and hydrogen. The carbon monoxide, methane, or hydrogen is consumed by the reduction of iron. Therefore, it is considered that the content of carbon and hydrogen in the carbide decreases, and the yield of the carbide used as the adsorbent decreases. On the other hand, when reducing the iron in a reducing gas atmosphere, since the reducing gas used for the reduction of iron is supplied from the outside, the metal forms a counter ion of the metal compound in the carbide or a carbide with oxygen and hydrogen. Reaction with carbon is suppressed. Therefore, it is considered that the reduction of the carbon content of the carbide used as the adsorbent is suppressed.

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. Further, in step S103, as the solution 120, a ferrous sulfate aqueous solution (FeSO ₄ ), a ferric sulfate aqueous solution (Fe (SO ₄ ) ₃ ), or a ferric polysulfate solution ([Fe ₂ (OH) _n ( SO ₄ ) _{3 −n / 2} ] _m , where 0 <n ≦ 2 and m = f (n)), the iron oxide and / or iron sulfide is contained in the adsorbent 10 obtained by the reduction treatment in step S113. May be attached. The iron oxide and / or iron sulfide may be present on the surface of the carbide or inside the pores (at least one of macropores 200, mesopores 210, and micropores 220).

(4) 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>
[Method of Manufacturing Adsorbent 10A]
A method for manufacturing the adsorbent 10A according to the second embodiment will be described with reference to FIG. The method for manufacturing the adsorbent 10A is similar to the method for manufacturing the adsorbent 10 according to the first embodiment shown in FIG. 1, except that the solution 120 is immersed and dried, and the porous material 100A to which the iron compound 111A is attached. Is different from the method for producing the adsorbent 10 of the first embodiment in that the is further immersed in an alkaline solution. In the following description of FIG. 6, description of portions common to FIG. 1 will be omitted, and different points from FIG. 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 drying the porous material 100A impregnated with the solution 120A in step S111A, the porous material 100A is immersed in an alkaline solution in step S115A. At this time, the iron compound 111A has adhered to the inner wall of the hole of the porous material 100A as in FIG. Therefore, when the porous material 100A is immersed in the alkaline solution, and the alkaline solution permeates into the pores of the porous material 100A and comes into contact with the iron compound 111A, at least a part of the iron compound 111A is hydroxylated. Thus, iron hydroxide is generated on the inner wall of the hole of the porous material 100A.

(4) After the production of the iron hydroxide, the porous material 100A is washed with water (Step S120A). By this washing, the alkali metal ions generated in the pores of the porous material 100A, the anions bonded to iron in the iron compound, and the alkali solution remaining in the pores can be removed. Here, the iron hydroxide present on the inner wall of the pores of the porous material 100A has a low solubility, and therefore is not easily discharged to the outside of the porous material 100A even after the above-described water washing. Further, if the inside of the porous material 100A is biased toward alkalinity, for example, the adsorptive power of phosphorus or the like is weakened. However, as described above, the alkali metal ions, anions, and alkali in the porous material 100A are washed by water. By removing the solution, it is possible to suppress the inside of the porous material 100A from being biased toward alkaline. Note that the water washing in step S120A may be omitted. After the drying in step S121A, washing may be performed.

In order to infiltrate the above-mentioned alkaline solution into the mesopores 210A and the micropores 220A, the iron compound 111A existing in the pores can be hydroxylated by performing degassing in the same manner as in Step S107A. A porous material 100A having iron hydroxide adhered to the inner wall can be obtained (Steps S117A, S119A, S120A, S121A). After the porous material 100A dried in step S121A is washed with water, the reduction treatment in step S113A is performed.

As the alkaline solution used in step S115A, a solution such as sodium hydroxide (NaOH) or potassium hydroxide (KOH) can be used.

工程 The above steps S115A to S121A may be repeated a plurality of times. Further, the steps S117A and S119A may be repeated a plurality of times. Steps S117A and S119A may be omitted.

As described above, according to the method for manufacturing the adsorbent 10A according to the present embodiment, the reduction treatment can be performed in a state where the iron compound 111A is hydroxylated. That is, the gas generated in the reduction process is harmless steam.

Here, a more specific example of the present embodiment will be described with reference to FIG. Here, a case where iron chloride solution 150A is used as solution 120A and sodium hydroxide solution 140A is used as the alkaline solution will be described. FIG. 7 is a conceptual diagram showing a specific method for producing iron hydroxide in the adsorbent according to one embodiment of the present invention. FIG. 7 shows the inner wall 101A of the holes (the macro holes 200A, the meso holes 210A, and the micro holes 220A) of the porous material 100A, and illustrates a phenomenon in a region surrounded by the inner wall 101A.

示す As shown in FIG. 7A, an anion (chloride ion 153A) paired with iron ion 151A exists in iron chloride solution 150A in addition to iron ion 151A. By impregnating the iron chloride solution 150A into the porous material 100A and removing the solvent contained in the iron chloride solution 150A by drying, solid iron chloride 155A precipitates on the inner wall 101A of the hole of the porous material 100A. (FIG. 7B).

When the sodium hydroxide solution 140A is impregnated into the porous material 100A in which iron chloride 155A is precipitated on the inner wall 101A, hydroxide ions in the sodium hydroxide solution react with the iron chloride in the porous material 100A. Iron hydroxide 141A, chloride ion 143A, and sodium ion 145A in the sodium hydroxide solution are generated (FIG. 7C). That is, when the sodium hydroxide solution 140A comes into contact with the iron chloride 155A deposited on the inner wall 101A, the hydroxide ions of the sodium hydroxide solution 155A are replaced by the chlorine of the iron chloride 155A by a chemical reaction, and the iron hydroxide 141A and the chloride are removed. Object ions 143A are generated. Since the iron hydroxide 141A has low solubility in water, it precipitates as a solid on the inner wall 101A and is retained in the porous material 100A. On the other hand, since sodium chloride has a high solubility in water, it exists as chloride ions 143A and sodium ions 145A, and can be removed from the pores of the porous material 100A by, for example, washing with water in step S120A ((D in FIG. 7). )). Further, by washing with water, excess sodium hydroxide solution 140A not used for the reaction in the pores can also be removed from porous material 100A (FIG. 7D). That is, of the iron compound (iron chloride) in the iron chloride solution 150A, the substance (chlorine) bonded to iron is anionized and discharged out of the porous material 100A together with the sodium hydroxide solution 140A.

In other cases, similarly to the above, in the pores of the porous material 100A, in the pores of the porous material 100A, iron hydroxide (solid) generated by a chemical reaction, anions and alkali metal ions ( Liquid) and excess alkali solution (liquid), but other than iron hydroxide can be removed by washing with water. Thereby, an element derived from the anion of the solution 120A (“chlorine” in the above example) can be removed before reduction, and the amount of acidic gas generated during the reduction treatment can be greatly suppressed. In the case where hydroxide is not generated in the production process of the adsorbent, hydrogen chloride gas is generated during reduction if the solution 120A is a solution containing iron chloride, and nitric acid is generated if the solution 120A is a solution containing iron nitrate. Gas is generated, and if the solution 120A is a solution containing iron sulfate, an acidic gas such as sulfuric acid gas is generated. Therefore, a scrubber for removing the acid gas is required. On the other hand, by generating hydroxide in the manufacturing process of the adsorbent as in the present embodiment, there is no need to provide a scrubber for removing the gas as described above, thereby simplifying the apparatus for manufacturing the adsorbent. Is possible.

<Modification of Second Embodiment>
A modification of the second embodiment will be described with reference to FIGS. FIG. 8 is a flowchart showing a method for manufacturing an adsorbent according to one embodiment of the present invention. FIG. 9 is a conceptual diagram showing a specific method for producing iron hydroxide in the adsorbent according to one embodiment of the present invention.

工程 The process shown in FIG. 8 is a process in which steps S107A to S111A are omitted from FIG. That is, after immersing the porous material 100A in the solution 120A, it is immersed in the alkaline solution without drying. FIG. 6 shows a production method in which the iron compound 111A is chemically reacted with the iron compound 111A in a state where the iron compound 111A is precipitated on the inner wall 101A of the hole of the porous material 100A to produce iron hydroxide 141A. The iron ion 110A in the solution 120A and the hydroxide ion 147A in the alkaline solution are chemically reacted to precipitate the iron hydroxide 141A on the inner wall 101A.

Here, a more specific example of the modification of the present embodiment will be described with reference to FIG. Since FIG. 9 is similar to FIG. 7, the description of the same features in FIG. 9 as those in FIG. 7 will be omitted. In the following description, a case where iron chloride solution 150A is used as solution 120A and sodium hydroxide solution 140A is used as the alkaline solution will be described.

As shown in FIG. 9A, in the porous material 100A that has not been dried after the porous material 100A has been immersed in the iron chloride solution 150A, iron ions 151A and chloride ions 153A are contained in the iron chloride solution 150A. Existing. When the sodium hydroxide solution 140A is supplied to the porous material 100A in this state, the sodium hydroxide solution 140A enters the pores of the porous material 100A by diffusion and infiltration (FIG. 9B). As shown in FIG. 9B, sodium ion 145A and hydroxide ion 147A are present in sodium hydroxide solution 140A.

When the sodium hydroxide solution 140A enters the pores of the porous material 100A, iron ions 151A, chloride ions 153A, sodium ions 145A, and hydroxide ions 147A are present in the pores of the porous material 100A. (C in FIG. 9). Although FIG. 9C illustrates a configuration in which the pores of the porous material 100A are replaced with the sodium chloride solution 140A from the iron chloride solution 150A, these solutions may be mixed. Iron ions 151A and hydroxide ions 147A undergo a chemical reaction in the pores of the porous material 100A to generate iron hydroxide 141A, which precipitates on the inner wall 101A of the pores of the porous material 100A (FIG. D)). By performing water washing in this state, chloride ions 153A, sodium ions 145A, and sodium hydroxide solution 140A other than iron hydroxide 141A can be removed from the holes (FIG. 9D).

According to the modification of the second embodiment, since it is not necessary to dry the porous material 100A after immersing it in the iron chloride solution 150A, it is possible to simplify the manufacturing process.

In the modified example of the second embodiment, the manufacturing method in which the porous material 100A is immersed in the alkaline solution is illustrated. However, since the alkaline solution enters the pores of the porous material 100A by diffusion and infiltration, the porous material immersed in the solution 120A is A method of supplying an alkaline solution to the surface of the material 100A may be employed. For example, an alkaline solution may be sprayed on the surface of the porous material 100A with a spray or the like.

<Third embodiment>
[Production method of adsorbent 10B]
A method for manufacturing the adsorbent 10B according to the third embodiment will be described with reference to FIG. The method for manufacturing the adsorbent 10B is similar to the method for manufacturing the adsorbent 10 according to the first embodiment shown in FIG. 1, but the solution 120B that permeates the pores of the porous material 100B contains iron. The method is different from the method for producing the adsorbent 10 of the first embodiment in that it is colloidal.

FIG. 10 is a flowchart showing a method for producing a solution containing iron according to an embodiment of the present invention. As shown in FIG. 10, the solution 120B used in the present embodiment is prepared by steps S131B to S135 as described in detail below. The following steps S131B to S135B are steps corresponding to step S103 shown in FIG.

First, in step S131B, the iron solution described in step S101 of FIG. 1 is prepared. Subsequently, in step S133B, the alkali solution described in step S115A of FIG. 6 is added to this iron solution. When the alkaline solution is added to the iron solution, the iron solution becomes a colloid containing iron hydroxide particles. Specifically, the aqueous iron solution exemplified above (an aqueous ferrous chloride solution, an aqueous ferric chloride solution, an aqueous ferrous nitrate solution, an aqueous ferric nitrate solution, an aqueous ferrous sulfate solution, or an aqueous ferrous sulfate solution) When an alkaline solution (a sodium hydroxide solution or a potassium hydroxide solution) is added to the aqueous solution), the iron aqueous solution becomes a colloid containing iron hydroxide particles. The solution in this state can be called a colloid solution. Subsequently, in step S135B, a dispersant as exemplified in the first embodiment is added.

コロイド This colloid solution contains iron hydroxide particles having a size of 1 nm or more and 100 nm or less. Therefore, by impregnating the colloid solution into the mesopores 210B and the micropores 220B, the iron hydroxide particles can penetrate into these pores.

By immersing the porous material 100B in the above colloid solution and drying after washing with water, or by immersing and drying and then washing with water, the iron hydroxide particles adhere to the inner walls of the pores of the porous material 100B. In addition, unreacted iron ions, anions paired with iron ions of the iron solution, and alkali metal ions can be removed from the pores of the porous material 100B. By performing a reduction treatment on the iron hydroxide particles, zero-valent iron attached to the inner wall of the pores of the porous material 100B can be obtained.

In addition, when the particles in the colloid solution can be sufficiently dispersed without using a dispersant, or even when the dispersion of the particles in the colloid solution is insufficient, the characteristics of the adsorbent 10B are not adversely affected. In this case, the step of adding a dispersant (step S135B) may be omitted.

As described above, according to the method for producing the adsorbent 10B according to the present embodiment, zero-valent iron can be obtained by reducing the iron hydroxide particles. For example, an iron chloride solution is used as the solution 120B. Even when used, solid iron hydroxide is formed inside the pores of the porous material, and sodium chloride is removed outside the pores, suppressing the amount of acid gas generated during the reduction process. can do.

In the above embodiment, an example of a method of depressurizing the porous material 100 (or 100A, 100B) while immersing it in the solution 120 (or 120A, 120B) will be described with reference to FIG. FIG. 11 is a diagram illustrating a method of reducing the pressure of a porous material immersed in a solution in the method for producing an adsorbent according to one embodiment of the present invention.

減圧 As shown in FIG. 11, the decompression container 400 has a container part 401 and a lid part 403. The container 401 has a shape capable of storing the solution 120. 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.

Further, as shown in FIG. 11, the solution 120 is supplied to the decompression container 400, and the porous material 100 is immersed in the solution 120. The case 500 containing the porous material 100 therein is submerged in the solution 120. The case 500 has a shape surrounding the internal space, and is submerged in the solution 120 with the porous material 100 stored in the internal space. That is, the case 500 can suppress the porous material 100 from rising and coming out of the liquid surface of the solution 120, and can lift the porous material 100 when removing the case 500 from the decompression container 400.

(4) The case 500 is provided with an opening large enough to allow the solution 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 open 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.

後に 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, the porous material 100 can be taken out while the excess solution 120 is dropped into the decompression container 400. .

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-described embodiment, and can be appropriately changed without departing from the spirit of the present invention. For example, those in which those skilled in the art appropriately add, delete, or change 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 of 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, # 101A: inner wall, # 110: iron ion, # 111: iron compound, # 120: solution, # 130: air bubbles, # 140A: sodium hydroxide solution, # 141A: iron hydroxide, # 143A: chloride Ion, $ 145A: sodium ion, $ 147A: hydroxide ion, $ 150A: iron chloride solution, $ 151A: iron ion, $ 153A: chloride ion, $ 155A: iron chloride, $ 200: macropore, $ 210: mesopore, $ 220: micropore , # 400: decompression container, # 410: container, # 403: lid, # 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

Carbonize organic matter to form carbides,
Infiltrate the solution containing iron into the pores of the carbide,
A method for producing an adsorbent, wherein the carbide impregnated with the solution containing iron is dried.
方法 The method for producing an adsorbent according to claim 1, wherein the solution contains iron ions.
The method for producing an adsorbent according to claim 1, wherein the solution is a colloid containing particles containing iron hydroxide.
方法 The method for producing an adsorbent according to claim 1, wherein the solution contains heme iron.
Infiltrate the alkaline solution into the dried pores of the carbide to produce iron hydroxide particles,
Discharging the alkaline solution out of the pores of the carbide;
The method for producing an adsorbent according to claim 1, wherein the carbide is dried.
Carbonize organic matter to form carbides,
In the pores of the carbide, impregnated with a solution containing iron ions and anions paired with the iron ions,
Producing iron hydroxide particles by impregnating the alkaline solution into the pores of the carbide impregnated with the solution,
Discharging the anion and the alkaline solution out of the pore,
A method for producing an adsorbent, wherein the carbide is dried.
7. The method for producing an adsorbent according to claim 5, wherein the iron hydroxide particles are reduced.
Drying the carbide impregnated with the solution containing iron, causing an iron compound to adhere to the carbide,
The method for producing an adsorbent according to claim 1, wherein the iron contained in the iron compound is reduced.
The method for producing an adsorbent according to any one of claims 1 to 8, wherein the pressure is reduced while the carbide is immersed in the solution.
The method for producing an adsorbent according to claim 7, wherein the reduction is performed using a gas containing hydrogen, carbon monoxide, or a hydrocarbon.
方法 The method for producing an adsorbent according to claim 7, wherein the reduction is performed at a temperature of 500 ° C. or higher using a gas containing carbon monoxide.
The method for producing an adsorbent according to claim 7, wherein the reduction is performed at a temperature of 100 ° C. or higher using a gas containing hydrogen.