WO2018207745A1

WO2018207745A1 - Flow pressure loss reducing adsorption system using hierarchical structure

Info

Publication number: WO2018207745A1
Application number: PCT/JP2018/017687
Authority: WO
Inventors: 和之石井; 恭子榎本
Original assignee: 国立大学法人東京大学
Priority date: 2017-05-08
Filing date: 2018-05-08
Publication date: 2018-11-15
Also published as: TW201906789A; JP7089263B2; JP2018187569A

Abstract

The present invention pertains to a flow pressure loss reducing system and method using a hierarchical structure, for the adsorption and removal of contaminants, for removing contaminants from aqueous environments, particularly flowing water. The present invention particularly pertains to a system and method for removing radioactive cesium from an aqueous environment (particularly flowing water) contaminated by radioactive cesium. Specifically, a system is provided that is arranged in a flow path for contaminated water, is for the adsorption and removal of contaminants in the contaminated water, and comprises: a plurality of cartridges including an adsorbent that adsorbs contaminants by coming in contact with contaminated water; and a means for holding the cartridges in the flow path. The system is characterized by: each of the cartridges comprising a container having a plurality of water through-holes, a plurality of adsorbents sealed in the container, and a means that prevents the adsorbent from flowing out of the water through-holes but does not prevent the adsorbent and the water from coming in contact; and the adsorbent being a porous structure comprising hydrophilic fibers and carrying a substance capable of trapping contaminants.

Description

Adsorption system with reduced flow pressure loss using hierarchical structure

The present invention relates to an aquatic environment, particularly a pollutant adsorption removal system and method using a hierarchical structure for removing pollutants from running water, particularly a water environment contaminated with radioactive cesium (especially running water). Relates to a decontamination system and method for radioactive cesium from

The unprecedented accident at the Fukushima Daiichi NPS due to the Great East Japan Earthquake that occurred on March 11, 2011 still has a serious impact on the lives of local residents as well as agriculture, fisheries and livestock industries. . The removal of radioactive materials such as iodine ( ¹³¹ I), cesium ( ¹³⁴ Cs, ¹³⁷ Cs), and strontium ( ⁹⁰ Sr) released into the environment by the accident as well as the convergence of the nuclear accident itself is currently It is an urgent issue. Especially a major radioactive material, environment 137Cs with a long half-life of about 30 years ⁽¹³⁷ Cs), in particular, sea, rivers, ponds, for removal from the water environment of lakes such as is currently various Various approaches are being considered by the institution.

For example, as a radioactive material adsorbent for adsorbing and removing cesium 137 from drained wastewater, a radioactive material recovery sheet in which zeolite is fixed to a nonwoven fabric using a binder resin has been reported (see, for example, Patent Document 1).
Moreover, a water purification filter cartridge for removing cesium using zeolite has been reported (for example, see Patent Document 2). This is intended to remove cesium by providing a filtration layer formed by winding a nonwoven fabric with zeolite particles fixed on the surface.
However, when zeolite is used, there is a problem that the same amount of radioactive waste as that of the used zeolite is generated.

Furthermore, as a radioactive substance adsorbent, a cesium adsorbent composed of a hydrophilic fiber substrate carrying a Prussian blue analog is known (for example, see Patent Document 3). This is a Prussian blue analogue fixed inside the fiber. Prussian blue is generally a powder substance that is insoluble in water, and it has been difficult to immobilize not only the surface of hydrophilic fibers but also the inside. First, it was successfully fixed inside, and according to this, cesium can be adsorbed and removed from the contaminated water. However, when removing radioactive substances from contaminated water, it is necessary to quickly purify a large amount of contaminated water. However, even if such a cesium adsorbent is used as a filter medium, there is a problem that a rapid purification treatment cannot be realized. .

Similarly, radioactive material adsorption / recovery in which a ferrocyanide compound is supported on a tubular woven fabric formed by knitting with a thread material to purify contaminated water by adsorbing rather than filtering the radioactive material An installation structure (for example, see Patent Document 5) of a storage container containing a radioactive cesium adsorbent used for a device (for example, see Patent Document 4), a flow path in the middle of flowing into a dam or pond from a mountain area, and the like has been reported. However, these devices are used by being installed in rivers and seawater, and do not quickly purify contaminated water flowing out in large quantities, and there is a problem that radioactive substances are not sufficiently removed.

JP2015-99140A JP 2013-88411 A Table 2013/27652 gazette JP 2014-122809 A JP 2014-98640 A

As described above, in the water environment decontamination methods that have been reported so far, used filter media and adsorbents become radioactive waste as they are, and a large amount of contaminated water is quickly treated, In addition, there is a problem to be improved in terms of sufficiently removing radioactive substances.

The inventors of the present invention have so far completed an invention relating to “a cesium adsorbent comprising a hydrophilic fiber substrate carrying a Prussian blue analog” (see, for example, Patent Document 3). Such a cesium adsorbent is obtained by immobilizing Prussian blue analogue on a hydrophilic fiber substrate, and is safe and easy to handle. In addition, since it can be obtained from an inexpensive and easily available material by a simple manufacturing method, it is excellent in application to environmental purification over a wide range from an economical aspect. Furthermore, depending on the object of decontamination, the cesium adsorbent can be easily processed into an optimal mode, and after adsorbing radioactive cesium in the environment, the transition of Prussian blue analogue (adsorbed with cesium) Only the adsorbent can be easily recovered without leaving the metal salt in the environment. In addition, since the adsorbent is made of a flammable hydrophilic fiber substrate, the adsorbent after use can be incinerated without any special treatment, and compared with conventional decontamination methods, radioactive waste This is advantageous in that the amount can be suppressed.

In order to solve the above-mentioned problems, the present inventors have processed the adsorbent and flowing water installed in the flow path in order to quickly treat the pollutant from the water environment, particularly flowing water, and sufficiently remove the pollutant. As a result of diligent investigation focusing on reducing the pressure loss of running water while improving the contact efficiency with water, we established a system for reducing and removing pollutant using a hierarchical structure. Further, by combining such a removal system and the cesium adsorbent developed by the present inventors, a decontamination system for radioactive cesium from a water environment, particularly flowing water, which is inexpensive and does not require the presence of an expert, is constructed. Was completed.

The present invention is as follows:
[1] A system for adsorbing and removing pollutants in polluted water installed in a flow path of polluted water, including a plurality of cartridges including an adsorbent that adsorbs pollutants by contacting with polluted water; And means for holding the cartridge in the flow path, each of the cartridges having a container having a plurality of water passage holes, a plurality of adsorbents enclosed in the container, and the adsorbent flowing out of the water passage holes And a means for preventing contact between the adsorbent and water, and the adsorbent is a porous structure made of hydrophilic fibers carrying a substance capable of trapping contaminants. And the system.
[2] A means for preventing the adsorbent from flowing out from the water passage hole but preventing the adsorbent and water from contacting each other is a mesh bag having a mesh size that allows water to pass and does not penetrate the adsorbent. The system according to [1], wherein the adsorbent is enclosed in a capsule in a state of being filled in a mesh bag.
[3] The system according to [1] or [2], wherein the average of the maximum lengths of the containers having water passage holes is 10 mm to 1 × 10 ³ mm.
[4] The system according to any one of [1] to [3], wherein the hydrophilic fiber is a cellulose fiber.
[5] The pollutant is radioactive cesium, the substance capable of trapping the pollutant is a transition metal salt of hexacyano metal acid, and the transition metal salt of hexacyano metal acid is fixed to a hydrophilic fiber. [1] to [4].
[6] The system according to [5], wherein the transition metal salt of hexacyanometal acid is iron (III) hexacyanoferrate (II) hydrate.
[7] A system for adsorbing and removing radioactive cesium in contaminated water installed in a flow path of water contaminated with radioactive cesium,
-Comprising a plurality of cartridges comprising an adsorbent that adsorbs radioactive cesium by contact with contaminated water, and means for holding the cartridges in said flow path;
Each of the cartridges has a substantially spherical capsule having a plurality of water passage holes, a plurality of adsorbents enclosed in the capsule, and a mesh having a size capable of passing water and not penetrating the adsorbents; A bag, wherein the adsorbent is enclosed in a capsule in a mesh bag, and the adsorbent is a porous fiber made of hydrophilic fibers carrying a transition metal salt of hexacyanometal acid A system, characterized in that a transition metal salt of hexacyanometal acid is fixed to a fiber.
[8] A method for adsorbing and removing contaminants in contaminated water,
(I) a step of installing a plurality of cartridges including an adsorbent that adsorbs contaminants in contact with contaminated water in the flow path;
(Ii) contacting the contaminated water with the adsorbent in the cartridge; and (iii) collecting the cartridge from the flow path; and (iv) collecting the adsorbent from the cartridge.
Here, a means for holding the cartridge in the flow path is provided, and each of the cartridges has a container having a plurality of water holes, a plurality of adsorbents enclosed in the container, and an adsorbent from the water holes. Means for preventing the outflow of the adsorbent, but does not hinder the contact between the adsorbent and water, and the adsorbent is a porous structure made of hydrophilic fibers carrying a substance capable of trapping contaminants. Features, a method.
[9] The pollutant is radioactive cesium, the substance capable of trapping the pollutant is a transition metal salt of hexacyano metal acid, and the transition metal salt of hexacyano metal acid is fixed to a hydrophilic fiber. The method according to [8].

In the system for adsorbing and removing contaminants in the contaminated water of the present invention, a porous structure made of hydrophilic fibers carrying a substance capable of trapping contaminants is used as an adsorbent. By using a porous structure as an adsorbent carrier, the surface area of the adsorbent increases, so the amount of substances that can trap contaminants increases, and the contact efficiency between contaminated water and the adsorbent is greatly increased. It is improved and the pollutant can be removed sufficiently. Moreover, in the system for adsorbing and removing pollutants in the contaminated water of the present invention, a plurality of adsorbents are further sealed in a container having a plurality of water passage holes, and a plurality of them are used as cartridges. Pressure loss can be reduced, and a large amount of contaminated water can be treated quickly. In this way, by using a hierarchical structure in which a plurality of porous structures are collected to form one cartridge, and a plurality of cartridges are collected to form one unit (system), the flow pressure loss reducing contaminants can be reduced. An adsorption removal system was established.

When the system of the present invention is a system that adsorbs and removes radioactive cesium in contaminated water, the adsorbent is a cesium adsorbent, and the cesium adsorbent has a Prussian blue analog as a hydrophilic fiber as will be described later. Since it is fixed to the fiber of the porous structure which consists of this, it is safe and easy to handle. Moreover, since it can be obtained from an inexpensive and easily available material by a simple manufacturing method, it is excellent in application to water environment purification over a wide range from an economical aspect. Further, after adsorbing radioactive cesium in the contaminated water, only the adsorbent can be easily recovered without leaving the transition metal salt of Prussian blue analog (adsorbed with cesium) in the water environment. Moreover, since the adsorbent is formed of a flammable hydrophilic fiber base material, it can be incinerated, which is advantageous in that the amount of radioactive waste can be suppressed as compared with conventional decontamination methods. .

It is an example of an adsorbent, and shows porous particles (diameter of about 4 mm) made of cellulose fibers carrying a Prussian blue analog. The left shows an example of a porous structure, a fiber rod (diameter: about 15 mm, height: 15 mm) made of cellulose composite fiber, and the right shows an adsorbent carrying Prussian blue analog on the fiber rod. 1A is a bag body in which about 3000 pieces of the adsorbent shown in FIG. 1A are packed in a mesh bag having a size that allows water to pass and does not penetrate the adsorbent, and (a) closes the opening of the mesh bag. Before, (b) shows after closing the opening part of a mesh bag. FIG. 2 is an example of a cartridge, in which (a) is a water passage hole, a capsule in which about 10 to 30 circular holes having a diameter of about 1.2 cm are formed, and the bag shown in FIG. 2 is enclosed; (b) Indicates a capsule enclosing a bag and a capsule not encapsulating. Fig. 4 shows a schematic diagram of a system using the cartridge of Fig. 3;

The present invention relates to a system that is installed in a contaminated water flow path to adsorb and remove contaminants in contaminated water. In the present invention, “polluted water” refers to water contaminated with harmful substances such as chemical substances (hereinafter referred to as “pollutants”). Examples of contaminants, mercury, lead, tin, copper, cadmium, nickel, cobalt, a heavy metal such as chromium, dioxin, cyanide, organic or inorganic compounds, such as arsenic compounds, or radioactive cesium ⁽¹³⁴ Cs, ¹³⁷ Cs) And the like. Accordingly, the contaminated water includes water environments such as polluted seas, rivers, ponds and lakes, water taken from the polluted water environment, and industrial wastewater. Among them, since the system of the present invention is suitable for adsorbing and removing radioactive cesium, the contaminated water includes water contaminated with radioactive cesium, that is, seas, rivers, ponds, lakes and the like contaminated with radioactive cesium. Water, water taken from the water environment contaminated with radioactive cesium, waste water containing radioactive cesium, groundwater, etc.

In the present invention, “water contaminated with radioactive cesium” refers to water containing radioactive cesium ( ¹³⁴ Cs, ¹³⁷ Cs). In particular, the radioactive cesium concentration indicates that cesium 134 is more than 60 Bq / L and cesium 137 is more than 90 Bq / L. These standards are guidelines established by law to safely dispose of waste. For example, if the radioactive cesium concentration is below these standards, it can be discharged into rivers, the sea, and the like.

In the present invention, the “flow path” refers to a path through which water flows, and may be an existing flow path such as a sea, a river, a water channel, or the like, and is provided separately as a part of the system of the present invention. Also good.

The system of the present invention includes a plurality of cartridges including an adsorbent that adsorbs contaminants by coming into contact with contaminated water, and means for holding the cartridge in the flow path. In the present invention, the “adsorbent” is a porous structure made of hydrophilic fibers carrying a substance capable of trapping contaminants.

In the present invention, “substances capable of trapping contaminants” can be appropriately selected by those skilled in the art depending on the contaminants intended to be adsorbed and removed using the system of the present invention. Typical of substances that can trap pollutants when the pollutants are heavy metals such as mercury, lead, tin, copper, cadmium, nickel, cobalt, chromium, or organic or inorganic compounds such as dioxins, cyanides, arsenic compounds Specific examples include activated carbon and various chelate resins. When the pollutant is radioactive cesium ( ¹³⁴ Cs, ¹³⁷ Cs), a typical example of a substance that can trap the pollutant is Prussian blue analog. Substances capable of capturing such contaminants can be obtained from reagent suppliers, or can be prepared from reagents available from reagent suppliers by those skilled in the art according to known methods.

The substance capable of trapping these contaminants is supported on the “porous structure made of hydrophilic fibers”. The hydrophilic fiber may be rephrased as a water absorbent fiber. The hydrophilic fiber is a general term for fibers that are generally easy to take up water molecules, and is typically a cellulose fiber. Examples of cellulose fibers include natural fibers such as wool, cotton, silk, hemp and pulp, regenerated fibers such as rayon, polynosic, cupra (Bemberg (registered trademark)), lyocell (Tencel (registered trademark)), or those A composite fiber is mentioned. Semi-synthetic fibers such as acetate and triacetate, or synthetic fibers such as polyamide, polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, polyester, polyacrylonitrile, polyolefin or polyurethane, or composites thereof The fiber may be modified by a known method to impart hydrophilicity. Moreover, as long as it has the desired hydrophilicity, it may be a composite material of hydrophilic fibers and synthetic fibers, for example, cellulose composite fibers of cellulose fibers and synthetic fibers (for example, polyolefin fibers such as polyethylene and polypropylene). . In view of price and availability, cellulose fibers or cellulose composite fibers are preferable as the hydrophilic fibers.

The porous structure made of hydrophilic fibers is not particularly limited to the shape or the like as long as it is composed of hydrophilic fibers and has voids through which water can permeate. The porosity of the porous structure (ratio of the volume of the space to the total volume of the structure) is at least about 10%, preferably about 30% or more, more preferably about 50% or more, especially Preferably it is about 75% or more. Typical examples of the structure porous structure include porous particles made of hydrophilic fibers and fiber rods.

Porous particles can be obtained from a specialist, or can be prepared by granulating a fine powder of hydrophilic fibers available from a specialist according to a method known to those skilled in the art. The porous particles may be substantially spherical porous particles, but the average particle diameter (median diameter) is about 1 to about 30 mm, preferably about 1 to about 10 mm, more preferably about 2 ~ 8mm. In order to increase the surface area of the adsorbent and improve the amount of the substance capable of trapping pollutants and the contact efficiency between the contaminated water and the adsorbent, the average particle diameter is preferably about 10 mm or less. In order to prevent outflow into contaminated water (running water) and facilitate recovery, the average particle size is preferably about 1 mm or more. The porosity of the porous particles is not particularly limited, but is preferably about 70 to about 98%, more preferably about 75 to about 95%. Porous particles, for example, porous cellulose particles are Viscopar® A (average particle size 2 mm, 4 mm; porosity 93%) or Viscopearl® P (average particle size 1 mm, 4 mm, 6 mm, 8 mm; 80% porosity), available from Rengo Co., Ltd.

The fiber rod can be obtained from a specialist, or can be prepared by molding a hydrophilic heat-fusible fiber available from a specialist according to a method known to those skilled in the art. The fiber rod is generally cylindrical, and examples thereof include those having a diameter of about 1 to about 30 mm, a length of about 1 to about 300 mm, and a porosity of about 50 to about 90%. The shape is not particularly limited. Such a fiber rod can be obtained from Asahi Textile Industry Co., Ltd., for example.

There is no particular limitation on the method for supporting a substance capable of trapping contaminants on a porous structure made of hydrophilic fibers, and those skilled in the art will use an appropriate method depending on the nature of the substance capable of trapping contaminants. Can be adopted. For example, when a substance capable of trapping pollutants is water-soluble, an aqueous solution of a substance capable of trapping pollutants is impregnated with a porous structure made of hydrophilic fibers to thereby remove a substance capable of trapping pollutants. A supported porous structure can be obtained. In addition, when a substance capable of trapping pollutants is water-insoluble, it can be granulated as composite particles by mixing the substances capable of trapping pollutants when granulating hydrophilic fiber fine powder. May be. An example in which the substance capable of trapping the contaminant is a Prussian blue analog will be described in detail below.

A cesium adsorbent in which a Prussian blue analog, particularly preferably Prussian blue is supported on a porous structure made of hydrophilic fibers, is characterized in that the Prussian blue analog is fixed not only on the surface of the fiber but also inside. To do. A “pigment” such as Prussian blue is insoluble in a medium such as water or an organic solvent and has no dyeing property to a substrate. Therefore, when dyeing (printing) a fiber substrate with a pigment, it is usually necessary to post-treat with a binder resin or the like and fix the pigment attached to the fiber surface. However, in the treatment with the binder resin, since the binder resin adheres to the surface of the substance that can simultaneously trap the contaminant (for example, Prussian blue analog), the surface activity is impaired and the trapping ability of the contaminant is reduced. Not desirable. In the cesium adsorbent according to the present invention, the Prussian blue analog reacts with “an inorganic salt of hexacyano metal acid” and “an inorganic compound containing a transition metal element” in the presence of a porous structure composed of hydrophilic fibers. It is formed in-situ and is present as fine particles on the surface and inside of the fiber, so it is stably fixed to the porous structure made of hydrophilic fibers regardless of the binder resin, etc. A decrease in capture ability can be avoided.

Here, the Prussian blue analog (that is, a transition metal salt of hexacyano metal acid) is a kind of cyano-bridged metal complex having hexacyano metal acid ions as a building element, and has a general formula: M ^A _m [M ^B ( CN) ₆ ] _n · hH ₂ O, which is understood to have a face-centered cubic structure in which the metal ions (M ^A , M ^B ) are alternately crosslinked with cyano groups. Here, M ^A is the first transition metal. Therefore, the Prussian blue analog according to the present invention may be rephrased as a transition metal salt of hexacyano metal acid. As the first transition metal, scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu And one or more metals selected from zinc (Zn). Preferably, one or more metals selected from iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), and zinc (Zn) are used, and more preferably copper (Cu ) Or iron (Fe), especially ferric iron (Fe (III)).

In the general formula, ^{M B} may be any metal species capable of forming a octahedral six-coordinate structure, preferably, chromium (Cr), manganese (Mn), iron (Fe), copper (Cu) and cobalt ( One or more metals selected from Co), more preferably iron (Fe) or copper (Cu), particularly ferrous iron (Fe (II)). Note in the general formula, m, the values of n and h is determined according to the oxidation number of M ^A and M ^B.

The Prussian blue analog may be a product obtained by a reaction between an inorganic salt of hexacyano metal acid and an inorganic compound containing a transition metal element, and any product represented by the above general formula may be used. The Prussian blue analog according to the present invention may include those in which some of the metal ions of the transition metal salt of hexacyano metal acid are substituted with alkali metal ions derived from the raw material.

For example, as a transition metal salt of hexacyanoferrate (II) which is an embodiment of the Prussian blue analog according to the present invention, its scandium (Sc) salt, titanium (Ti) salt, vanadium (V) salt, chromium ( Cr) salt, manganese (Mn) salt, iron (Fe) salt, cobalt (Co) salt, nickel (Ni) salt, copper (Cu) salt, zinc (Zn) salt, and one or more thereof Mixed salts are mentioned. Preferably, iron (Fe) salt, cobalt (Co) salt, nickel (Ni) salt, copper (Cu) salt, zinc (Zn) salt of hexacyanoferrate (II) acid, and one or more thereof A mixed salt is mentioned, More preferably, a copper (Cu) salt or an iron (Fe) salt, especially a ferric iron (Fe (III)) salt is mentioned. The transition metal salt of hexacyanoferrate (II) acid according to the present invention is a product obtained by the reaction of an inorganic salt of hexacyanoferrate (II) acid and an inorganic compound containing a transition metal element, formula (However, the M ^B, particularly ferrous (Fe (II)) is a) may be any, including those represented by, but part of the metal ions, alkali metal ions such as derived from the raw material May be substituted with.

A ferric (Fe (III)) salt of hexacyanoferrate (II), which is the most preferred example of the Prussian blue analog according to the present invention, is also called Prussian blue or bitumen and has been used as a pigment for a long time. ing. Its ideal chemical composition is Fe (III) ₄ [Fe (II) (CN) ₆ ] ₃ · xH ₂ O (x = 14 to 16) (ie, “iron (III) hexacyanoferrate (II) hydrate) )), But some iron ions may be substituted depending on the production method. Prussian blue according to the present invention is obtained by a reaction between an inorganic salt of hexacyanoferrate (II) and an inorganic compound containing ferric iron (III), and includes those having the above chemical composition. What is necessary is that some iron ions may be substituted with raw material-derived alkali metal ions or the like.

“Inorganic salt of hexacyanometal acid” is water-soluble and forms a Prussian blue analog according to the present invention (ie, transition metal salt of hexacyanometal acid) by reaction with an inorganic compound containing a transition metal element. There is no particular limitation as long as it is possible. Examples include alkali metal salts (sodium salt, potassium salt, etc.) of hexacyano metal acid, mixed salts thereof, or hydrates thereof. Specifically, hexacyanochromium (III) acid, hexacyanomanganese (II) acid, hexacyanoiron (II) acid or hexacyanocobalt (III) acid alkali metal salt (sodium salt, potassium salt, etc.), or a mixed salt thereof Or a hydrate thereof.

For example, when the hexacyanometallic acid is hexacyanoiron (II) acid, the inorganic salt of hexacyanoiron (II) acid is water-soluble and reacts with an inorganic compound containing a transition metal element to form hexacyanoiron (II There is no particular limitation as long as it can form a transition metal salt of an acid. Specific examples include potassium hexacyanoferrate (II), sodium hexacyanoferrate (II), or a mixed salt thereof, or a hydrate thereof. The use of potassium hexacyanoferrate (II) or its hydrate is preferred.

The “inorganic compound containing a transition metal element” is water-soluble and forms a Prussian blue analog of the present invention (that is, a transition metal salt of hexacyano metal acid) by reaction with an inorganic salt of hexacyano metal acid. There is no particular limitation as long as it is possible. Examples of the inorganic compound containing such a transition metal element include halides, nitrates, sulfates, perchlorates, mixed salts thereof, and hydrates of the first transition metal. For example, halides such as ferric chloride (III), cobalt chloride (II), nickel chloride (II); nitrates such as ferric nitrate (III), cobalt nitrate (II), nickel nitrate (II); sulfuric acid Examples thereof include sulfates such as ferric iron (III) and cobalt sulfate (II); perchlorates such as ferric iron (III) perchlorate; or a mixed salt thereof, or a hydrate thereof.

For example, the inorganic compound containing ferric iron (III) is not particularly limited as long as it is water-soluble and can form Prussian blue by reaction with an inorganic salt of hexacyanoferrate (II) acid. For example, ferric chloride (III), ferric nitrate (III), ferric sulfate (III), ferric perchlorate (III), or a mixed salt thereof, or a hydrate thereof may be mentioned. .

The cesium adsorbent according to the present invention can be produced according to the method described in International Publication No. 2013/027652. Typically, (a) a step of treating a porous structure comprising hydrophilic fibers with an aqueous solution of an inorganic salt of hexacyanometal acid; and (b) a substrate treated in step (a) is treated with a transition metal element. It is produced by the manufacturing method including the process of processing with the aqueous solution of the containing inorganic compound. Note that the order of steps (a) and (b) may be reversed.

The adsorbent according to the present invention is collected from several tens to several tens of thousands, for example, about 20 to about 20,000, preferably about 50 to about 5,000, and is enclosed in a “container having a water passage hole”. Form. The size and material of the “container” are not particularly limited in size, material, and the like, but it is preferable to use a substantially spherical container from the viewpoint of ease of filling and reduction of pressure loss of running water. The diameter of the spherical container can be about 10 mm to about 1.0 × 10 ³ mm, preferably about 30 mm to about 0.5 × 10 ³ mm, more preferably about 40 mm to about 0.2 × 10 ³ mm. ³ is a mm, polystyrene, plastic capsules polypropylene or the like. Such capsules are cheap, easily available, and easy to process, and may be capsules for capsule toys.

The “water hole” provided in the container does not impair the independence of the container or the strength against the flowing water pressure of the contaminated water, and does not prevent the contaminated water from entering the container in the flow path. There is no particular limitation as long as the size and number are sufficient to allow sufficient contact. Preferably, about 3 to about 50 substantially circular holes having a diameter of about 0.5 to about 3 cm, more preferably about 5 to 30 substantially circular holes having a diameter of about 1 to 2 cm, are provided as water passage holes in the container. .

The cartridge according to the present invention includes “means for preventing the adsorbent from flowing out from the water passage hole but not preventing the adsorbent from contacting with water”. Such means prevents the adsorbent from flowing out of the water passage hole, but is not particularly limited as long as it does not hinder contact between the adsorbent and water. For example, in the present invention, in consideration of the size of the water passage hole and the size of the adsorbent, the size of the water passage hole may be a size that allows water to pass and does not penetrate the adsorbent. It is considered that the adsorbent is prevented from flowing out of the hole but provided with means that do not hinder the contact between the adsorbent and water. Preferably, a mesh bag having a mesh size that allows water to pass and does not allow the adsorbent to penetrate therethrough is used. Tens to tens of thousands of adsorbents are collected and sealed in a spherical container in a state of being filled in a mesh bag. The material of the mesh bag and the size of the mesh prevent the adsorbent from flowing out from the water passage hole, but are not particularly limited as long as the contact between the adsorbent and water is not hindered, preferably polyethylene, polypropylene, It is made of resin such as polyester and has a mesh of 20 to 200 mesh.

Tens to hundreds of cartridges according to the present invention are collected and installed in the flow path by “means for holding the cartridge”. The means for holding the cartridge is not particularly limited as long as it keeps the cartridge within a predetermined range of the flow path against the contaminated water flowing through the flow path, and inhibits the flow of water and does not significantly increase the pressure loss. . For example, a wire mesh basket suitable for the width and depth of the flow path may be installed in the flow path, and several tens to several hundreds of cartridges may be placed and held there. The cartridge may be put into a net and put into a flow path, and held so as not to be poured into running water.

The present invention also relates to a method for adsorbing and removing contaminants in contaminated water. The method of the present invention includes (i) a step of installing a plurality of cartridges in the flow path including an adsorbent that adsorbs contaminants by contacting the contaminated water, and (ii) contaminated water and adsorbents in the cartridge. (Iii) a step of recovering the cartridge from the flow path, and (iv) a step of recovering the adsorbent from the cartridge.

Preferably, the method of the present invention also relates to a method for adsorbing and removing radioactive cesium in contaminated water, wherein the pollutant is radioactive cesium.

In these methods, each of the cartridges has a container having a plurality of water passage holes, a plurality of adsorbents enclosed in the container, and the adsorbent is prevented from flowing out of the water passage holes. And the adsorbent is a porous structure made of hydrophilic fibers carrying a substance capable of trapping contaminants. Specific embodiments and examples of “pollutant”, “substance capable of trapping pollutant”, “porous structure comprising hydrophilic fibers”, “adsorbent”, “cartridge” and the like in the method of the present invention are as described above. It is synonymous with.

The present invention is not limited to the specific embodiments and examples described above, and various modifications can be made within the scope of the present invention depending on the purpose and application.

Claims

A system for adsorbing and removing pollutants in polluted water installed in a path of polluted water, comprising a plurality of cartridges containing adsorbents that adsorb pollutants by contact with the polluted water, and the flow Means for holding the cartridge in the path, each of the cartridges having a container having a plurality of water passage holes, a plurality of adsorbents enclosed in the container, and preventing the adsorbent from flowing out of the water passage holes. Comprises a means that does not hinder the contact between the adsorbent and water, and the adsorbent is a porous structure made of hydrophilic fibers carrying a substance capable of trapping contaminants, system.
The means for preventing the adsorbent from flowing out from the water passage hole but not hindering the contact between the adsorbent and water is a mesh bag having a mesh size that allows water to pass and does not penetrate the adsorbent. The system according to claim 1, wherein the material is enclosed in a capsule in a mesh bag.
The system according to claim 1 or 2, wherein the average of the maximum length of the container having water passage holes is 10 mm to 1 x 10 3 mm.
The system according to any one of claims 1 to 3, wherein the hydrophilic fiber is a cellulose fiber.
The pollutant is radioactive cesium, the substance capable of trapping the pollutant is a transition metal salt of hexacyano metal acid, and the transition metal salt of hexacyano metal acid is fixed to a hydrophilic fiber. The system according to any one of 1 to 4.
The system according to claim 5, wherein the transition metal salt of hexacyano metal acid is iron (III) hexacyanoferrate (II) hydrate.
A system for adsorbing and removing radioactive cesium in contaminated water by installing it in a flow path of water contaminated with radioactive cesium,
-Comprising a plurality of cartridges comprising an adsorbent that adsorbs radioactive cesium by contact with contaminated water, and means for holding the cartridges in said flow path;
Each of the cartridges has a substantially spherical capsule having a plurality of water passage holes, a plurality of adsorbents enclosed in the capsule, and a mesh having a size capable of passing water and not penetrating the adsorbents; A bag, wherein the adsorbent is enclosed in a capsule in a mesh bag, and the adsorbent is a porous fiber made of hydrophilic fibers carrying a transition metal salt of hexacyanometal acid A system, characterized in that a transition metal salt of hexacyanometal acid is fixed to a fiber.
A method for adsorbing and removing contaminants in contaminated water,
(I) a step of installing a plurality of cartridges including an adsorbent that adsorbs contaminants in contact with contaminated water in the flow path;
(Ii) contacting contaminated water with the adsorbent in the cartridge;
(Iii) collecting the cartridge from the flow path; and (iv) collecting the adsorbent from the cartridge.
Here, a means for holding the cartridge in the flow path is provided, and each of the cartridges has a container having a plurality of water holes, a plurality of adsorbents enclosed in the container, and an adsorbent from the water holes. Means for preventing the outflow of the adsorbent, but does not hinder the contact between the adsorbent and water, and the adsorbent is a porous structure made of hydrophilic fibers carrying a substance capable of trapping contaminants. Features, a method.
The pollutant is radioactive cesium, the substance capable of trapping the pollutant is a transition metal salt of hexacyano metal acid, and the transition metal salt of hexacyano metal acid is fixed to a hydrophilic fiber. 9. The method according to 8.