JP6598239B2 - Fluorine adsorbent and method for producing the same - Google Patents

Description

  The present invention relates to a pellet made of a carbonaceous composite formed by dispersing metal oxide magnetic particles in a carbon matrix containing a graphene sheet.

  In recent years, a method for adding a new function to a carbonaceous material by chemically treating the carbonaceous material or combining a carbonaceous material and a metal compound has been reported.

  Patent Document 1 describes that amorphous carbon containing graphene sheets obtained by carbonizing cellulose is subjected to heat treatment (sulfonation treatment) in concentrated sulfuric acid or fuming sulfuric acid. Thus, it is described that a sulfo group is introduced into the amorphous carbon to obtain a solid acid, and a metal catalyst is obtained by reacting it with a metal salt.

Patent Document 2 discloses graphite-coated metal particles obtained by mixing a carbonaceous substance and a metal-containing substance and heating the mixture to 1600 ° C. to 2800 ° C. in an inert gas atmosphere. There are also described iron oxide magnetic materials such as magnetite (Fe ₃ O ₄ ) and hematite (Fe ₃ O ₄ ) as an example of the metal-containing substance. The composite material disclosed in Patent Document 2 is obtained by covering iron oxide particles with graphite, and the main component thereof is iron oxide.

  The present inventors have invented a carbonaceous composite in which magnetic particles of metal oxide are dispersed in an amorphous carbon matrix (Patent Document 3). Unlike the substances described in Patent Documents 1 and 2, this carbonaceous composite is a dispersion of metal oxide magnetic particles in an amorphous carbon matrix. And this carbonaceous composite_body | complex can control the motion with an external magnetic field, although a carbonaceous material is a main component. It was reported that this carbonaceous composite is a porous body and can adsorb alkaline substances such as cesium ions efficiently.

  However, since the carbonaceous composite is a powder, there is a problem that handling properties are poor. Therefore, a carbonaceous composite having good handleability has been demanded.

JP 2009-268960 A Japanese Patent Laid-Open No. 9-143502 JP 2013-35743 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a carbonaceous composite having good handleability and a method for producing the same.

  The above-described problem is a pellet made of a carbonaceous composite in which magnetic particles of metal oxide are dispersed in a carbon matrix containing a graphene sheet, and the ratio of the number of metal atoms to the number of carbon atoms (Metal / C ) Is 0.0005 to 0.5, and the saturation magnetization is 5 emu / g or more.

At this time, it is preferable that the BET specific surface area is 100 m ² / g or more. Further, the ratio (Ms / Mr) of the saturation magnetization (Ms) to the residual magnetization (Mr) is preferably 20 or more.

  The above-mentioned problem is a method for producing the pellet, wherein the first and second metal salts selected from the group consisting of iron salt, cobalt salt and nickel salt are mixed with water-soluble polysaccharide in the presence of water. A step, a second step of carbonizing the mixture obtained in the first step to obtain a carbonaceous composite, a third step of molding the obtained carbonaceous composite, and a molded carbonaceous composite. It is solved also by providing the manufacturing method of the pellet characterized by including the 4th process heated in active gas atmosphere.

  At this time, in the third step, it is preferable to form the mixture after mixing the carbonaceous composite, the binder, and water to obtain a mixture. In the third step, it is also preferable to form the mixture after mixing the carbonaceous composite, binder, water and chemicals for activation to obtain a mixture. The binder is preferably a water-soluble polysaccharide.

  A preferred embodiment of the present invention is an adsorbent comprising the pellets.

  A method for removing an adsorbed material, in which the adsorbent and a liquid containing the adsorbed material are brought into contact with each other to adsorb the adsorbed material contained in the liquid, and then the adsorbent is recovered by a magnetic force. It is an aspect.

  ADVANTAGE OF THE INVENTION According to this invention, providing a carbonaceous composite_body | complex with favorable handleability and its manufacturing method can be provided.

It is the figure which showed the result of the adsorption test of the fluorine ion in Reference Example 1, Example 1 , and Comparative Examples 9-11. It is the figure which showed the result of the Raman spectroscopic measurement of the pellet obtained in Example 1 and Reference Examples 2-5 . It is the figure which showed the method of measuring the breaking strength of the pellet of Example 1. FIG. It is the figure which showed the magnetic characteristic of the pellet of Example 1 and Reference Examples 2-5 .

  The present invention relates to a pellet made of a carbonaceous composite in which magnetic particles of metal oxide are dispersed in a carbon matrix containing a graphene sheet. So far, the present inventors have produced a carbonaceous composite in which magnetic particles of metal oxide are dispersed in a carbon matrix containing a graphene sheet. And it was reported that this carbonaceous complex can be controlled by an external magnetic field. This carbonaceous composite can be used as an adsorbent, or can be used as a catalyst by supporting a transition metal, an enzyme, or the like. However, since the carbonaceous composite is a powder, there is a problem that handling properties are poor. As a result of intensive studies, the present inventor succeeded in making this carbonaceous composite into pellets with good handleability.

  The pellet in the present invention refers to a powder made into a lump and has a sphere equivalent diameter of 1 mm or more. From the viewpoint of handleability, the equivalent sphere diameter is preferably 1.5 mm or more. The shape of the pellet is not particularly limited, and examples thereof include a sphere, a disk, a column, a prism, and a cylinder.

  The ratio of the number of metal atoms to the number of carbon atoms (Metal / C) in the pellet of the present invention is 0.0005 to 0.5. When the ratio of the number of metal atoms to the number of carbon atoms (Metal / C) is less than 0.0005, the magnetic properties of the pellet are insufficient, and there is a possibility that the movement is difficult to control by an external magnetic field. The ratio of the number of metal atoms to the number of carbon atoms (Metal / C) is preferably 0.001 or more. On the other hand, when the ratio of the number of metal atoms to the number of carbon atoms (Metal / C) exceeds 0.5, it may not be used as an adsorbent. The ratio of the number of metal atoms to the number of carbon atoms (Metal / C) is preferably 0.25 or less.

  The saturation magnetization of the pellet of the present invention is 5 emu / g or more. When the saturation magnetization is less than 5 emu / g, the responsiveness of the pellet to an external magnetic field is lowered, which is not preferable. The saturation magnetization is preferably 10 emu / g or more, more preferably 20 emu / g or more, and further preferably 30 emu / g or more. On the other hand, the saturation magnetization is usually 200 emu / g or less.

  The residual magnetization of the pellet of the present invention is preferably 1 emu / g or less. When the remanent magnetization exceeds 1 emu / g, the pellets may be magnetically aggregated. The remanent magnetization is more preferably 0.7 emu / g or less, and further preferably 0.5 emu / g or less.

  In the present invention, the ratio (Ms / Mr) of the saturation magnetization (Ms) to the residual magnetization (Mr) of the pellet is improved from the viewpoint of further improving the responsiveness to the external magnetic field and preventing the pellets from aggregating magnetically. It is preferably 20 or more, and more preferably 50 or more.

  The pellet of the present invention preferably has a small coercive force, that is, soft magnetism. Specifically, the coercive force of the pellet of the present invention is preferably 500 Oe or less. When the coercive force exceeds 500 Oe, residual magnetization tends to remain, and the pellets may be magnetically aggregated. Therefore, it is preferable that hysteresis is hardly seen in the magnetization curve of the pellet of the present invention. The coercive force is more preferably 200 Oe or less, further preferably 100 Oe or less, and particularly preferably 50 Oe or less.

The magnetic particles in the present invention are particles that react to a magnetic force, and the movement can be controlled by an external magnetic force. The magnetic particles in the present invention are made of a metal oxide, and the kind thereof is not particularly limited as long as it reacts with magnetic force. However, as described above, if the coercive force of the magnetic particles is large, the residual magnetization increases, and the pellets may be magnetically aggregated. From the viewpoint of relatively small coercive force and easy availability, the metal oxide is preferably at least one selected from the group consisting of iron oxide, cobalt oxide and nickel oxide, and more preferably iron oxide. preferable. Examples of the iron oxide include magnetite (Fe ₃ O ₄ ), hematite (Fe ₂ O ₃ ), and maghemite (γ-Fe ₂ O ₃ ).

In the present invention, the carbon forming the matrix includes a graphene sheet. The graphene sheet has a structure in which aromatic rings are condensed and connected on a two-dimensional plane. Here, when carbon includes a graphene sheet, carbon atoms having a dangling bond such as an amorphous carbon called a D band near a peak caused by vibration in a hexagonal lattice of a carbon atom called a G band and a D band near 1350 cm ^−1. The resulting peak is observed.

The average size of the graphene sheet can be calculated based on the ratio (D / G) of the D band to the peak intensity of the G band according to the Raman spectrum. For example, in the carbonaceous composite obtained in Example 1 of the present application, the ratio (D / G) is about 0.88, and the average size of the graphene sheets contained therein is about 55 nm. The ratio (D / G) is preferably 0.1 to 2.25, and more preferably 0.5 to 2.0.

  The pellet of the present invention preferably contains amorphous carbon. Amorphous carbon generally refers to carbon that does not have a clear crystal structure, such as diamond or graphite. It can be confirmed by measurement by X-ray diffraction that the pellet contains amorphous carbon. Amorphous carbon does not detect a sharp peak in X-ray diffraction, or even if a peak is detected, the shape of the peak is broad.

The BET specific surface area of the pellet of the present invention is preferably 100 m ² / g or more. By having such a large BET specific surface area, improvement in catalyst performance and adsorption capacity can be expected. The BET specific surface area is more preferably 300 m ² / g or more, and further preferably 500 m ² / g or more. On the other hand, if the specific surface area is too large, the mechanical strength of the pellet may be lowered. Therefore, the BET specific surface area is usually 2000 m ² / g or less.

The pore volume determined by the BJH (Barrett, Joyner, and Halenda) method of the pellet of the present invention is preferably 0.02 to 1 cm ³ / g. When the pore volume is less than 0.02 cm ³ / g, it may be difficult to introduce a functional group into the pellet. On the other hand, when the pore volume exceeds 1 cm ³ / g, the mechanical strength of the pellet may be lowered.

  It is also preferable that the average pore diameter of the pellet of the present invention determined by the BJH method is 1 to 50 nm. When the average pore diameter is less than 1 nm, when the pellet is used as an adsorbent, the adsorbing ability may be lowered. Further, it may be difficult to introduce a functional group into the pellet. On the other hand, when the average pore diameter exceeds 50 nm, the mechanical strength of the pellet may be lowered. More preferably, it is 20 nm or less.

  Although the manufacturing method of the pellet of the present invention is not particularly limited, the preferable manufacturing method is at least one metal salt selected from the group consisting of iron salt, cobalt salt and nickel salt and water-soluble. A first step of mixing polysaccharides in the presence of water, a second step of carbonizing the mixture obtained in the first step to obtain a carbonaceous composite, and a third step of molding the obtained carbonaceous composite And a fourth step of heating the formed carbonaceous composite in an inert gas atmosphere.

  The cation component of the metal salt is not particularly limited as long as the metal oxide reacts with magnetic force when it becomes a metal oxide. The cation component of the metal salt is preferably at least one ion selected from the group consisting of iron, cobalt, and nickel, and more preferably an iron ion. The anion component of the metal salt is not particularly limited, and examples thereof include nitrate ion, chloride ion, sulfate ion, phosphate ion, carbonate ion, borate ion, and carboxylic acid. Among them, the anion component of the metal salt is preferably nitrate ion from the viewpoint that the decomposition temperature is low and the anion component does not remain after decomposition. From these viewpoints, the metal salt used in the first step is preferably at least one selected from the group consisting of iron nitrate, cobalt nitrate, and nickel nitrate, and more preferably iron nitrate.

  The polysaccharide used in the first step is not particularly limited as long as it is a water-soluble polysaccharide. Examples of water-soluble polysaccharides include cellulose derivatives and salts thereof, starch, and dextrin. Among these, cellulose derivatives and salts thereof are preferred, and cellulose derivative salts are more preferred from the viewpoint of water solubility. Preferred examples of the cellulose derivative include carboxymethyl cellulose, and examples of the salt include alkali metal salts.

  The mixing operation in the first step is not particularly limited. The polysaccharide powder may be added to and mixed with the metal salt aqueous solution, or the metal salt powder may be added to and mixed with the polysaccharide aqueous solution. Metal salt powder and polysaccharide powder may be added to water and mixed. An aqueous metal salt solution and an aqueous polysaccharide solution may be mixed. The kind of water used in the first step is not limited, and not only sufficiently purified water such as ion exchange water and distilled water but also tap water can be used.

  In the second step, a carbonaceous composite is obtained by carbonization. The carbonization is preferably performed by heating in an inert gas atmosphere such as argon gas or nitrogen gas. Before the carbonization treatment in the second step, it is preferable to dry the mixture obtained in the first step in advance to remove moisture. The drying method is not particularly limited, and heat drying, reduced pressure drying, or the like can be employed. Although the drying temperature at the time of heat-drying will not be specifically limited if it is the temperature which can remove the water | moisture content in a mixture, It is suitable that it is 40 degreeC or more. When the drying temperature is less than 40 ° C., there is a possibility that water in the mixture cannot be sufficiently removed. The drying temperature is more preferably 60 ° C. or higher. Further, the drying temperature is usually 100 ° C. or less from the viewpoint of energy consumption and cost. The drying temperature at this time is a set temperature in the drying apparatus used for drying the mixture. The drying time is set in relation to the drying temperature, but can be set as appropriate so that water in the mixture can be sufficiently removed.

  The heating temperature in the second step is not particularly limited as long as the carbonization of the mixture proceeds, but is preferably 80 ° C. or higher. When the heating temperature is less than 80 ° C., the carbonization of the polysaccharide becomes insufficient or the metal salt is not oxidized, and a carbonaceous composite in which magnetic particles of the metal oxide are dispersed in the carbon matrix is obtained. There is a risk that it will not be possible. The heating temperature at this time is a set temperature in the heating device used for carbonization of the mixture. Although the mixture obtained in the first step depends on the metal salt and the dry state, when it is heated to 80 ° C. or higher, self-combustion starts and the temperature of the mixture itself reaches 400 ° C. or higher and carbonization can proceed. The heating temperature is more preferably 100 ° C. or higher, and further preferably 150 ° C. or higher. On the other hand, it is also preferable that the heating temperature is 1000 ° C. or lower. When heating temperature exceeds 1000 degreeC, there exists a possibility that the graphene sheet in a carbonaceous composite body may grow too much as a result of progressing carbonization. From the viewpoint of energy consumption and cost, the heating temperature is more preferably 800 ° C. or less, and more preferably 600 ° C. or less. The heating time is set in relation to the heating temperature, but can be appropriately set so that the polysaccharide carbonization proceeds sufficiently.

  The heating device is not particularly limited, and any heating device of an electric heating type, a hot air type, or a direct fire type can be used. In order to separate the gas generated by carbonization of the mixture and the solid particles contained in the gas, a dust collector is preferably connected to the heating device. The dust collector is not particularly limited, and a cyclone dust collector or a filter dust collector is employed. A scrubber may be connected to the heating device. The scrubber is not particularly limited, and a stored water scrubber or a pressurized water scrubber is employed. Industrially, it is preferable to carbonize the mixture using a rotary kiln from the viewpoint of the uniformity of carbonization treatment and the continuous productivity of the carbonaceous composite.

  In the manufacturing method of this invention, it is preferable to further provide the process of washing the carbonaceous composite obtained at the 2nd process with water. When a by-product or a metal salt remains in the carbonaceous composite obtained in the second step, the metal salt is removed by washing the carbonaceous composite with water to obtain a pellet having a large specific surface area. There is no particular limitation on the washing method, and a method of extracting metal salts contained in the carbonaceous composite by bringing water into contact with the carbonaceous composite, or mixing with water and the carbonaceous composite and then filtering using a filter medium. A method to separate is mentioned. A Soxhlet extractor or the like can be used for extraction, and a Kiriyama funnel, a Buchner funnel, or the like can be used for filtration. Examples of industrial filtration methods include a filter press method, a belt press method, and a screw press method. The water used for washing is not particularly limited, but distilled water, ion exchange water, and the like are preferable. Further, an aqueous solution containing a small amount of acid such as hydrochloric acid or acetic acid may be used in order to efficiently remove the metal salt.

  In the third step, the obtained carbonaceous composite is molded. The method for forming the carbonaceous composite is not particularly limited, and examples thereof include pressing, extrusion, and rolling. At this time, it is preferable to form the mixture after mixing the carbonaceous composite, the binder, and water to obtain a mixture.

  The amount of the binder is preferably 0.1 parts by mass or more with respect to 100 parts by mass of the carbonaceous composite. When the amount of the binder is less than 0.1 parts by mass with respect to 100 parts by mass of the carbonaceous composite, there is a possibility that the carbonaceous composite cannot be formed into pellets, and it is more preferably 1 part by mass or more. On the other hand, the amount of the binder is preferably 50 parts by mass or less with respect to 100 parts by mass of the carbonaceous composite. When the amount of the binder exceeds 50 parts by mass with respect to 100 parts by mass of the carbonaceous composite, a pellet having a small specific surface area may be obtained, and it is more preferably 30 parts by mass or less.

  The binder is not particularly limited as long as it can form a carbonaceous composite into pellets, but is preferably a water-soluble polysaccharide from the viewpoint of moldability and strength. Examples of water-soluble polysaccharides include cellulose derivatives and salts thereof, starch, and dextrin. Of these, cellulose derivatives and salts thereof are preferred. Examples of cellulose derivatives include carboxymethyl cellulose. Examples of the salt include alkali metal salts such as sodium salt. From the viewpoint of water solubility, a salt of a cellulose derivative is more preferable, and an alkali metal salt of carboxymethyl cellulose, particularly a sodium salt is preferable.

  The amount of water is not particularly limited as long as it can mix the carbonaceous composite and the binder, and is usually 10 to 300 parts by weight with respect to 100 parts by weight of the carbonaceous composite.

  In the fourth step, pellets are obtained by heating the formed carbonaceous composite in an inert gas atmosphere. The heating temperature is usually 300 ° C. or higher, and preferably 500 ° C. or higher. On the other hand, if the heating temperature is too high, the graphene sheet in the carbide grows too much and is chemically stabilized, and a pellet having a large specific surface area may not be obtained. The heating temperature is preferably 1500 ° C. or less. And it can also shape | mold in a desired shape and a magnitude | size by cut | disconnecting the obtained pellet.

  At this time, if the BET specific surface area of the obtained pellet is large, improvement in catalyst performance and adsorption capacity can be expected. Therefore, it is preferable to activate the obtained pellets. Examples of the activation method include a chemical activation method and a gas activation method. The chemical activation method is a method of forming pores in the raw material by mixing the raw material and the chemical and heating it in an inert gas atmosphere. The gas activation method is a method of forming pores in a raw material by bringing the raw material into contact with high-temperature steam, carbon dioxide gas (combustion gas), oxygen (air), or the like. As a method for activating the pellets, any of the chemical activation method and the gas activation method can be adopted, and the gas activation method and the chemical activation method can be combined.

Especially, it is preferable that activation is chemical activation from a viewpoint which can activate a carbonaceous composite_body | complex uniformly. The following method (1) and method (2) are mentioned as methods for chemical activation of the pellets.
Method (1): Method of mixing and heating the pellets obtained in the fourth step and the chemical for activation Method (2): In the third step, for carbonaceous composite, binder, water and activation A method in which a chemical is mixed to obtain a mixture, and then the mixture is formed and heated.
The method (2) is preferable in that a uniformly activated pellet is obtained.

  As chemicals for activation, known chemicals such as zinc chloride, potassium hydroxide, sodium hydroxide, phosphoric acid, and potassium sulfide can be used. At this time, if the amount of the chemical is small, the carbonaceous composite may not be activated. From this viewpoint, the amount of the chemical is preferably 20 parts by mass or more, and more preferably 100 parts by mass or more with respect to 100 parts by mass of the carbonaceous composite. On the other hand, when the amount of the chemical is large, the activation proceeds too much, and the strength of the resulting pellet may be reduced. From this viewpoint, the amount of the activation chemical is preferably 1000 parts by mass or less and more preferably 300 parts by mass or less with respect to 100 parts by mass of the carbonaceous composite. In addition, the amount of the binder and water in the method (2) may be the above-described amount.

  The heating temperature in the method (2) is not particularly limited as long as it is a temperature capable of activating the carbonaceous composite, and is usually 300 ° C. or higher, and preferably 500 ° C. or higher. Surprisingly, it has been found that the magnetic properties of the pellet change depending on the heating temperature. The heating temperature is 620 ° C. or higher from the viewpoint of increasing the saturation magnetization value to further improve the responsiveness to the external magnetic field and reducing the coercive force value to prevent the pellets from aggregating magnetically. Is preferable, and it is more preferable that it is 670 degreeC or more. On the other hand, if the heating temperature is too high, the graphene sheet in the carbide grows too much and is chemically stabilized, and a pellet having a large specific surface area may not be obtained. The heating temperature is preferably 1500 ° C. or less.

  When chemical activation is performed, metal salts may remain in the obtained pellets. The pellet may be washed with water to remove this metal salt. At this time, an aqueous solution containing an acid such as hydrochloric acid may be used in order to efficiently remove the metal salt. Further, when heating at a temperature equal to or higher than the boiling point of the chemical used for activation, the metal salt volatilizes, so that washing may be omitted.

  The pellets thus obtained are porous and have a large specific surface area. Therefore, since a functional group can be introduced or a metal can be supported, it can be used as an excellent catalyst precursor and can also be used as an adsorbent. Moreover, the obtained pellet can also be sulfonated with sulfuric acid or the like. By doing so, it can be used as a solid acid. Moreover, the pellets thus obtained are also excellent in magnetic properties.

  Among these, a preferred embodiment of the present invention is an adsorbent made of pellets. The substance to be adsorbed (adsorbed substance) is not particularly limited. Since the pellet of the present invention often has an acidic functional group such as a carboxyl group on its surface, it can adsorb an alkaline substance. Examples of such substances include alkali metal ions such as cesium ions, alkaline earth metal ions such as strontium ions, and basic molecules such as methylene blue.

  Further, as a result of further investigation, the present inventor has found that this adsorbent can adsorb fluorine ions efficiently despite having an acidic functional group on the surface. Therefore, a fluorine adsorbent is also a preferred embodiment of the present invention. The reason why fluorine ions can be adsorbed is not necessarily clear, but it is presumed that the magnetic particles of metal oxide dispersed in a carbon matrix have some influence on the adsorption of fluorine ions.

  The liquid to be treated using the adsorbent of the present invention is not particularly limited as long as it contains an adsorbed substance. The liquid is preferably an aqueous solution, and examples thereof include groundwater and industrial wastewater containing an adsorbed substance. Since the adsorbent of the present invention is adsorbed to the magnet, only the adsorbent can be recovered by the magnet. When the liquid containing the substance to be adsorbed is an aqueous solution containing a solid content, it is difficult to recover only the adsorbent from the aqueous solution. From this viewpoint, the liquid to be treated using the adsorbent of the present invention is preferably an aqueous solution containing an adsorbed substance and a solid content. Examples of the solid content contained in the aqueous solution include stone, sand, earth, and ash. The aqueous solution may contain an organic solvent.

  Furthermore, the adsorbent of the present invention is one in which magnetic particles of metal oxide are dispersed in a carbon matrix, and is not a binder obtained by binding magnetic particles and adsorbent with a binder. Therefore, the magnetic particles and the adsorbent are not separated.

  There is also a method for removing an adsorbed material, in which the adsorbent comprising the carbonaceous composite is brought into contact with a liquid containing the adsorbed substance to adsorb the adsorbed substance contained in the liquid, and then the adsorbent is recovered by magnetic force. It is a preferred embodiment of the present invention.

  At this time, when the liquid containing the substance to be adsorbed is an aqueous solution containing solids such as stone, sand, earth, and ash, it is difficult to recover only the adsorbent from the aqueous solution. For example, it is very difficult to recover only the adsorbent by filtration. In particular, when the adsorbent and the solids have the same size, the adsorbent alone cannot be recovered by filtration. In addition, only the adsorbent cannot be recovered from the aqueous solution by centrifugation, and the solid content is recovered together with the adsorbent. It is also difficult to separate only the adsorbent from the mixture containing the solid content and the adsorbent.

  However, since the adsorbent adsorbed on the magnet is used in the removal method of the present invention, only the adsorbent can be recovered from groundwater or industrial wastewater containing solids. From this viewpoint, in the removal method of the present invention, it is preferable that the adsorbent is brought into contact with the aqueous solution containing the adsorbed substance and the solid content to adsorb the adsorbed substance contained in the aqueous solution.

  A magnet is usually used for collecting the adsorbent. The kind of magnet is not particularly limited, and examples thereof include a permanent magnet, an electromagnet, and a superconducting magnet.

  Hereinafter, the present invention will be described more specifically with reference to examples.

Reference example 1
[Production of carbon composite sheet]
(Synthesis of carbonaceous composite)
Capacity placed in a container of 20L and iron (III) nitrate nonahydrate _{(Fe (NO 3) 3 ·} 9H 2 O) 120g of tap water 16L, was stirred with a portable mixer. 240 g of powdered sodium carboxymethylcellulose (hereinafter sometimes abbreviated as CMC · Na, manufactured by Wako Pure Chemical Industries, Ltd., model number: 039-01335) is charged into the obtained aqueous solution using a powder metering machine. The mixture was further stirred to obtain a gel-like mixture. The obtained gel-like mixture was dried at 65 ° C. for 3 days using a blow-type drying furnace until 300 g of the dried mixture was obtained. The dried mixture was finely pulverized using a pulverizer, and then placed in a heating container connected to a cyclone dust collector, and carbonized by heating at 250 ° C. for 1 hour in a nitrogen atmosphere. The obtained carbide was washed with distilled water for 6 hours using a Soxhlet extractor, dried at 105 ° C. for about 24 hours using a constant temperature drying furnace, and sieved to obtain a carbonaceous composite having a particle size of 150 μm or less. Obtained.

(Preparation of paste)
To 0.64 mL of distilled water, 0.1 g of binder CMC / Na is added and stirred to obtain an aqueous solution. Then, 0.589 g of the obtained carbonaceous composite is added to the aqueous solution and kneaded to obtain a carbonaceous composite. A paste containing was obtained (see Table 1).

(Molding process)
The obtained paste was filled into a mold having a size of 31.3 mm, a width of 10.6 mm, and a depth of 35.0 mm (hereinafter sometimes abbreviated as mold A). The molded product was taken out from the mold and placed on an alumina porcelain firing boat (“ACE97 boat ACE-CB” manufactured by Tokyo Glass Instruments Co., Ltd.). The fired boat was placed in a quartz tube (inner diameter 46 mm × outer diameter 50 mm × length 1200 mm), and this quartz tube was set in a programmed tubular electric furnace (“TMF-500N” manufactured by ASONE Corporation). Heating in the furnace was started at a temperature rising rate of 8.3 ° C./min and a nitrogen flow rate of 200 mL / min, and after confirming that the temperature in the furnace reached 1000 ° C., the temperature was maintained for 3 hours. After 3 hours, the temperature in the furnace was lowered to room temperature by natural cooling. In this manner, a carbonaceous composite sheet having a length of 10.6 mm, a width of 31.3, and a thickness of 2 mm was obtained (hereinafter sometimes abbreviated as a sheet). Moreover, the obtained paste was extruded from a hole having a diameter of 2 mm, formed into a cylindrical shape, and heated to obtain a cylindrical carbonaceous composite pellet. Thereby, it turned out that the pellet which consists of a carbonaceous composite_body | complex of a desired shape is obtained by shape | molding the obtained paste.

[Evaluation]
(Measurement of specific surface area, pore volume, pore diameter)
The adsorption isotherm of the obtained sheet was measured by a nitrogen adsorption method (BET method) using a specific surface area / pore distribution measuring device. The BET specific surface area values are shown in Table 1. Moreover, the analysis by the BJH (Barrett, Joyner, and Halenda) method was performed, and the average pore diameter and the total pore volume of the sheet were calculated, respectively. These results are also shown in Table 1. As a specific surface area / pore distribution measuring apparatus, “Tristar II 3020” manufactured by Shimadzu Corporation was used.

(Fluorine ion adsorption test)
The obtained sheet was cut into 2 mm × 2 mm × 2 mm to obtain pellets. And the adsorption test of the fluorine ion was done by the method described below using this pellet.

(1) Preparation of aqueous potassium fluoride solution 0.3 g of potassium fluoride was dissolved in 100 mL of distilled water. This aqueous solution was diluted 10 times with distilled water to prepare an aqueous potassium fluoride solution used in this experiment. When the fluorine ion concentration of the obtained aqueous solution was measured by the method (3) below, the fluorine ion concentration was 99 mg / L (concentration A).

(2) Adsorption test of fluorine ions 100 mL of the aqueous solution prepared by the method of (1) above and 1.0 g of the pellets were placed in a beaker. Using a shaker, the aqueous solution in the beaker was stirred at room temperature for 24 hours at a rotation speed of 175 rpm. After the shaking, when the magnet was brought close to the beaker, the pellets in the aqueous solution were attracted to the magnet and attached to the magnet through the wall of the beaker. Thereby, it was confirmed that a pellet can be collect | recovered using a magnet. The aqueous solution was filtered to remove pellets in the aqueous solution, and the filtrate was recovered. Using 30 mL of the obtained filtrate, the fluorine ion concentration was measured by the following method (3). As a result, the fluorine ion concentration of the filtrate was 78 mg / L (concentration B).

(3) Measurement of fluorine ion concentration The fluorine ion concentration in the aqueous solution was measured by the “distilled / lanthanum-alizarin complexone coloring CFA method” described in JIS K 0170-6 (2011). For the measurement of absorbance, “Auto Analyzer 3” manufactured by BLC was used.

Using the values of concentration A and concentration B obtained, the amount of fluorine ion adsorbed on 1 kg of the pellets used was determined by the following formula. The results are shown in Table 1 and FIG.
Fluorine ion adsorption amount (mg / kg) = [(concentration A (mg / L) −concentration B (mg / L)) × amount of potassium fluoride aqueous solution used in the test (L)] / the pellet used in the test Amount (kg)

Example 1
In the preparation of the paste, a sheet was obtained and evaluated in the same manner as in Reference Example 1 except that 1.32 g of zinc chloride, which is a chemical for activation, was further added. The results are shown in Table 1. In addition, the following “X-ray analysis”, “analysis by Raman spectroscopy”, “breaking strength test”, and “measurement of magnetic properties” were also performed.

(X-ray analysis)
The sheet was divided and the cross section was analyzed using an energy dispersive X-ray analyzer (EDS) connected to a scanning electron microscope (SEM). As a result, the ratio of the number of metal atoms to the number of carbon atoms (Metal / C) was 0.0046. “JSM-6510” manufactured by JEOL Ltd. was used as a scanning electron microscope apparatus (SEM / EDS).

(Analysis by Raman spectroscopy)
Using the Raman spectrometer, the sheet obtained in Example 1 was pulverized into powder and subjected to Raman measurement. The results are shown in FIG. As shown in FIG. 2, a peak called G band around 1580 cm ^-1 is a peak called D band around 1350 cm ^-1 was confirmed, respectively. The G band is a peak caused by vibrations in the hexagonal lattice of carbon atoms, and the D band is a peak caused by carbon atoms having dangling bonds such as amorphous carbon. The ratio of the D band to the peak intensity of the G band was about 0.88. Based on this, it was found that the average size of the graphene sheet contained in the sheet obtained in Reference Example 1 was about 55 nm. . As the Raman spectroscopic measurement apparatus, a micro Raman spectrophotometer “inVia Reflex St” manufactured by RENISHAW was used.

(Break strength test)
As shown in FIG. 3, a yarn was wound around the center of the sheet obtained in Example 1 , and a weight was hung on the yarn. And the weight of the weight when this sheet broke was measured. As a result, the maximum load capacity was 819.8 g.

(Measurement of magnetic properties)
Using the sample vibration type magnetometer, the obtained sheet was pulverized into powder and packed in an acrylic cell holder to measure the magnetic properties. The results are shown in Table 1 and FIG. As a vibrating sample magnetometer, VSM-15 manufactured by Toei Kogyo Co., Ltd. was used.

Reference Examples 2-5
Except for changing the temperature in the furnace as shown in Table 1, pellets were obtained in the same manner as in Example 1 and evaluated. The results are shown in Table 1.

Reference Examples 6-9
In preparing the paste, pellets were obtained and evaluated in the same manner as in Example 1 except that the amount of each component was changed as shown in Table 1. The results are shown in Table 1.

Comparative Example 1
A mixture obtained by adding 1 g of the carbonaceous composite obtained in Reference Example 1 and 1 g of CMC · Na as a binder was obtained. This mixture was put into a mold A and pressed at room temperature at a press pressure of 180 kgf / cm ² for 1 hour. The molded product thus obtained was very brittle and could not maintain a three-dimensional shape.

Comparative Example 2
A mixture obtained by adding 1 g of the carbonaceous composite obtained in Reference Example 1 and 1 g of CMC · Na as a binder was obtained. This mixture was put into a mold A and pressed at room temperature at a press pressure of 180 kgf / cm ² for 1 hour. The pressed mixture is transferred to a three-necked flask, and heating is started at a heating rate of 3.3 ° C./min and a nitrogen flow rate of 150 mL / min in the three-necked flask, and it is confirmed that the temperature in the flask has reached 400 ° C. And held at that temperature for 1 hour. After 1 hour, the temperature was lowered to room temperature by natural cooling. The molded product thus obtained was very brittle and could not maintain a three-dimensional shape.

Comparative Example 3
2 g of polyethylene pellets (Mw: 50000) obtained from Scientific Polymer Products, INC were pulverized for 60 seconds using a pulverizer (“WB-1” manufactured by Osaka Chemical Co., Ltd.) and the carbonaceous material obtained in Reference Example 1 A composite was obtained by mixing 0.5 g of the composite and 0.5 g of pulverized polyethylene (hereinafter sometimes abbreviated as PE) to obtain a mixture. (It may be abbreviated as “Die B”) and pressed at room temperature using a hand hot press (“HHP-1” manufactured by AS ONE Co., Ltd.) The pressing pressure at this time is 100 kgf / cm ² , and the pressing time The molded product thus obtained was very brittle and could not maintain a three-dimensional shape.

Comparative Example 4
PE was obtained in the same manner as in Comparative Example 3. Then, 1 g of the carbonaceous composite obtained in Reference Example 1 and 2 g of PE were mixed to obtain a mixture. This mixture was placed in a mold A and pressed at room temperature at a pressing pressure of 220 kgf / cm ² for 1 hour. After the pressed mixture was transferred to a three-necked flask, heating was started at a heating rate of 2.7 ° C./min and a nitrogen flow rate of 150 mL / min in the three-necked flask, and after confirming that the temperature reached 80 ° C., Hold at that temperature for 2.5 hours. After 2.5 hours, the mixture was reheated at a temperature rising rate of 1.2 ° C./min to confirm that the temperature in the flask reached 150 ° C., and held at that temperature for 1 hour. After 1 hour, the temperature was lowered to room temperature by natural cooling. The molded product thus obtained was very brittle and could not maintain a three-dimensional shape.

Comparative Example 5
A mixture obtained by adding 0.1 g of the carbonaceous composite obtained in Reference Example 1 and 0.9 g of sulfur (powder, manufactured by Wako Pure Chemical Industries, Ltd.) as a binder was obtained. This mixture was put in a mold B and pressed at room temperature using a hand hot press (“HHP-1” manufactured by ASONE CORPORATION). The pressing pressure was 180 kgf / cm ² and the pressing time was 0.5 hours. The molded product thus obtained was very brittle and could not maintain a three-dimensional shape.

Comparative Example 6
A mixture obtained by adding 0.2 g of the carbonaceous composite obtained in Reference Example 1 and 0.8 g of sulfur (powder, manufactured by Wako Pure Chemical Industries, Ltd.) as a binder was obtained. This mixture was placed in a mold B and pressed using a hand hot press (“HHP-1” manufactured by ASONE CORPORATION). The pressing temperature at this time was 200 ° C., the pressing pressure was 200 kgf / cm ² , and the pressing time was 0.5 hours. The molded product thus obtained was very brittle and could not maintain a three-dimensional shape.

Comparative Example 7
A mixture was obtained by mixing 1 g of the carbonaceous composite obtained in Reference Example 1 and 1 g of coal tar pitch (manufactured by JEF Chemical Co., Ltd.) as a binder. This mixture was put in a mold A and pressed at room temperature at a press pressure of 200 kgf / cm ² for 1 hour and 40 minutes. The molded product thus obtained was very brittle and could not maintain a desired three-dimensional shape.

Comparative Example 8
A mixture was obtained by mixing 0.5 g of the carbonaceous composite obtained in Reference Example 1 and 0.5 g of coal tar pitch (manufactured by JEF Chemical Co., Ltd.) as a binder. This mixture was placed in a mold A and pressed at room temperature at a pressing pressure of 240 kgf / cm ² for 1 hour. The pressed mixture was placed on an alumina porcelain firing boat (“ACE97 boat ACE-CB” manufactured by Tokyo Glass Instruments Co., Ltd.). The fired boat was placed in a quartz tube (inner diameter 46 mm × outer diameter 50 mm × length 1200 mm), and this quartz tube was set in a programmed tubular electric furnace (“TMF-500N” manufactured by ASONE Corporation). Heating in the furnace was started at a temperature rising rate of 8.3 ° C./min and a nitrogen flow rate of 200 mL / min, and after confirming that the temperature in the furnace reached 500 ° C., the temperature was maintained for 1 hour. After 1 hour, the temperature in the furnace was lowered to room temperature by natural cooling. The molded product thus obtained was very brittle and could not maintain a three-dimensional shape.

Comparative Example 9
After adding 1.32 g of zinc chloride as a chemical for activation to 0.64 mL of distilled water and stirring to obtain an aqueous solution, 0.589 g of the carbonaceous composite obtained in Reference Example 1 was added to this aqueous solution ( (See Table 1). The obtained mixture was placed on an alumina porcelain firing boat (“ACE97 boat ACE-CB” manufactured by Tokyo Glass Instruments Co., Ltd.) without being molded. The fired boat was placed in a quartz tube (inner diameter 46 mm × outer diameter 50 mm × length 1200 mm), and this quartz tube was set in a programmed tubular electric furnace (“TMF-500N” manufactured by ASONE Corporation). Heating in the furnace was started at a temperature rising rate of 8.3 ° C./min and a nitrogen flow rate of 200 mL / min, and after confirming that the temperature in the furnace reached 1000 ° C., the temperature was maintained for 3 hours. After 3 hours, the temperature in the furnace was lowered to room temperature by natural cooling. The obtained product was in the form of powder (hereinafter, sometimes simply abbreviated as powder). In the same manner as in Reference Example 1, “specific surface area, pore volume, pore diameter measurement” and “fluorine ion adsorption test” were performed. The results are shown in Table 1.

Comparative Example 10
The powdery carbonaceous composite obtained in “Synthesis of carbonaceous composite” in Reference Example 1 was evaluated. The evaluation was carried out in the same manner as in Reference Example 1 including “measurement of specific surface area, pore volume and pore diameter” and “fluorine ion adsorption test”, and in the same manner as in Example 1 , “analysis by Raman spectroscopy” and “Measurement of magnetic properties” was also performed. The results are shown in Table 1.

Comparative Example 11
A fluorine ion adsorption test was performed in the same manner as in Reference Example 1 using commercially available activated carbon (activated carbon “Hokuetsu Y-10S” manufactured by Ajinomoto Fine Techno Co., Ltd.). The results are shown in Table 1.

Claims (5)

A fluorine adsorbent comprising a pellet made of a carbonaceous composite in which magnetic particles of iron oxide are dispersed in a carbon matrix containing a graphene sheet;
A fluorine adsorbent characterized in that the ratio of the number of iron atoms to the number of carbon atoms ( Fe 2 / C) is 0.0005 to 0.5 and the saturation magnetization is 5 emu / g or more. The fluorine adsorbent according to claim 1, wherein the BET specific surface area is 100 m ² / g or more. The fluorine adsorbent according to claim 1 or 2, wherein a ratio (Ms / Mr) of saturation magnetization (Ms) to residual magnetization (Mr) is 20 or more. It is a manufacturing method of the fluorine adsorbent in any one of Claims 1-3,
A first step of mixing an iron salt and a water-soluble polysaccharide in the presence of water;
A second step of carbonizing the mixture obtained in the first step at 80 to 1000 ° C. to obtain a carbonaceous composite;
To 100 parts by mass of the obtained carbonaceous composite, 0.1 to 50 parts by mass of water-soluble polysaccharide, 10 to 300 parts by mass of water, and 20 to 1000 parts by mass of zinc chloride are obtained to obtain a mixture, A third step of forming the mixture ;
Method for producing an adsorbent, characterized in that it comprises a fourth step of heating the molded carbonaceous composite at 300 to 1,500 ° C. in an inert gas atmosphere. After the adsorption of fluorine ions contained in the adsorbent and the liquid contacting the liquid containing fluorine ions according to claim 1, method for removing fluorine ions collecting the adsorbent by a magnetic force .

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