Water treatment materials

Abstract

To provide a water treatment material that has excellent cesium adsorption performance and very little shedding of the adsorbent. 【Solution means】A water treatment material containing a cesium adsorbent material composed of a carrier and a cesium adsorbent supported on the carrier, wherein the carrier is a modified fiber in which a polymer containing a cationic monomer (x) as a constituent monomer is bonded to the fiber, the cationic monomer (x) is a cationic monomer (x1) represented by the general formula (1), and the cation charge density in the polymer containing the cationic monomer (x) is 2.0 to 5.5 meq / g based on the weight of the polymer. CH2=C(R 4 , - )-CO-X-Q-N + (R 2 )(R 3 )(R 4 )·Z - (1) [In formula (1), R 1 is a hydrogen atom or a methyl group, R 2 ~R 4 are each independently a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, X is an oxygen atom or NH, Q is an alkylene group having 1 to 6 carbon atoms, and Z - represents a monovalent anion group.]

Description

[Technical Field]

[0001] This invention relates to a water treatment material. [Background technology]

[0002] Zeolites and Prussian blue are known to have excellent adsorption capabilities for cesium, a radioactive element. Following the Fukushima Daiichi nuclear power plant accident caused by the Great East Japan Earthquake, these materials have attracted considerable attention as cesium adsorbents due to their performance. Currently, as decontamination efforts for the radioactive material progress, there is a growing need for these materials to be supported on fiber materials as adsorbents.

[0003] Methods for supporting various adsorbents on fiber materials include rolling methods in which the adsorbents are added directly and then rolled to support them, adhesive methods in which the adsorbents are supported in combination with a primary binder, and spray drying methods (see, for example, Patent Documents 1 to 3). In addition, to prevent the supported adsorbents from falling off, a method is known in which, after supporting the adsorbents, an adhesive binder such as polyurethane, polyester, or polyacrylic acid ester is treated as a secondary binder to cover the surface of the fiber material (see, for example, Patent Document 1).

[0004] Furthermore, in order to overcome the shortcomings of the conventional technology described above, a fibrous mass-shaped water treatment material is known that exhibits less shedding of cesium adsorbent. (See, for example, Patent Document 4.)

[0005] However, in the above-mentioned rolling method, adhesion method, spray drying method, etc., there were problems such as the inability to increase the concentration of the adsorbent on the surface of the obtained fiber material. Furthermore, there was a risk of environmental pollution spreading due to the detachment of the supported adsorbent. Particularly in the case of cesium adsorbents, it is predicted that if the adsorbent that has adsorbed radioactive cesium at a high concentration from the fiber material detaches, it may cause further environmental pollution and lead to a serious situation. Further, when a Prussian blue-type complex containing a cyanide compound is used as the adsorbent, it is predicted that the total cyanide concentration standard regulated by the wastewater standard may be exceeded due to detachment. Although it is possible to suppress the detachment of the adsorbent by using a binder in combination as described above, there were problems such as the inability to obtain the target adsorption performance because the adsorbent was covered by the binder. Also, even when a complex was supported on a fibrous water treatment material, since it was not directly bonded to the base material, there was a problem that it would detach even after adsorbing radioactive substances.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0007] The problem of the present invention is to solve the drawbacks of the prior art as described above, and to provide a water treatment material that is excellent in cesium adsorption performance and has very little detachment of the adsorbent.

Means for Solving the Problems

[0008] As a result of intensive studies to solve the above problems, the present inventors have reached the present invention. That is, the present invention is a water treatment material containing a cesium adsorbing material composed of a carrier and a cesium adsorbent supported on the carrier, wherein the carrier is a modified fiber in which a polymer containing a cationic monomer (x) as a constituent monomer is bonded to the fiber, the cationic monomer (x) is a cationic monomer (x1) represented by the general formula (1), and the cationic charge density in the polymer containing the cationic monomer (x) is 2.0 to 5.5 meq / g based on the weight of the polymer. CH2=C(R , ,

[0011] , )-CO-X-Q-N + (R 2 )(R 3 )(R 4 )·Z - (1) [In formula (1), R 1 is a hydrogen atom or a methyl group, R 2 ~R 4 are each independently a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, X is an oxygen atom or NH, Q is an alkylene group having 1 to 6 carbon atoms, and Z - represents a monovalent anion.]

Effects of the Invention

[0009] The water treatment material of the present invention has excellent cesium adsorption performance and very little desorption of the adsorbent.

Modes for Carrying Out the Invention

[0010] Hereinafter, the details of the present invention will be described.

[0011] The water treatment material of the present invention is a water treatment material containing a cesium adsorbing material composed of a carrier and a cesium adsorbent supported on the carrier, wherein the carrier is a modified fiber in which a polymer containing a cationic monomer (x) as a constituent monomer is bonded to the fiber, the cationic monomer (x) is a cationic monomer (x1) represented by the general formula (1), and the cationic charge density in the polymer containing the cationic monomer (x) is 2.0 to 5.5 meq / g based on the weight of the polymer. CH2=C(R1 )-CO-XQN + (R 2 )(R 3 )(R 4 )·Z - (1) [In formula (1), R 1 R is a hydrogen atom or a methyl group. 2 ~R 4 Each of the following is independently a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, X is an oxygen atom or NH, Q is an alkylene group having 1 to 6 carbon atoms, Z - This represents a monovalent anion.

[0012] The water treatment material in the present invention is a water treatment material comprising a cesium-adsorbing material comprising a carrier and a cesium adsorbent supported on the carrier.

[0013] The water treatment material may include fibers made of the cesium-adsorbing material, nonwoven fabrics made using the fibers, woven fabrics made using the fibers, twisted yarns made using the fibers, non-porous membranes made of the cesium-adsorbing material, porous membranes made of the cesium-adsorbing material, and particles made of the cesium-adsorbing material. Among these, fibers, nonwoven fabrics, woven fabrics, and twisted yarns are preferred because they have a large surface area and can be expected to have a high cesium adsorption rate. Furthermore, the cesium-adsorbing material contained in the water treatment material may be a processed product made from the aforementioned fibers, twisted yarns, and nonwoven fabrics. Examples of processed products include cut fibers and twisted yarns, such as chenille (braided cord). Among these, cut fibers have low pressure loss when packed into a column and used in a flow system, and high cesium adsorption efficiency can be obtained by increasing the water flow rate. If the cesium-adsorbing material contained in the water treatment material is a woven or nonwoven fabric, it is also possible to combine cesium adsorption and filtering functions.

[0014] Useful fibers as carrier materials for water treatment materials include synthetic fibers (fibers made of polyester, polyamide, poly(meth)acrylic acid ester, polyvinyl chloride, polyvinylidene chloride, polyethylene, polypropylene, polyurethane, polyvinyl alcohol, phenolic resin, melamine resin, and epoxy resin, etc.), natural fibers (cellulose fibers such as cotton, animal fibers, mineral fibers, and regenerated fibers), or blends thereof. Of these, cellulose, polyester, polyamide, poly(meth)acrylic acid ester, polyvinyl chloride, polyvinylidene chloride, polyethylene, polypropylene, polyurethane, polyvinyl alcohol, phenolic resin, melamine resin, and epoxy resin are preferred from the viewpoint of modifiable processability.

[0015] The carrier is a modified fiber to which a polymer containing a cationic monomer (x) bonded to the fiber is attached as a constituent monomer.

[0016] The polymer contains a cationic monomer (x) as a constituent monomer. Examples of the cationic monomer (x) include the cationic monomer (x1) represented by general formula (1) and the cationic monomer (x2) other than (x1). CH2=C(R 1 )-CO-XQN + (R 2 )(R 3 )(R 4 )·Z - (1) [In formula (1), R 1 R is a hydrogen atom or a methyl group. 2 ~R 4 Each of the following is independently a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, X is an oxygen atom or NH, Q is an alkylene group having 1 to 6 carbon atoms, Z - This represents a monovalent anion.

[0017] In formula (1), R 1 This is either a hydrogen atom or a methyl group. In formula (1), R 2 ~R 4 Each of these is independently a hydrogen atom and an alkyl group having 1 to 22 carbon atoms. Examples of alkyl groups having 1 to 22 carbon atoms include methyl, ethyl, propyl, butyl, and hexyl groups. Of the alkyl groups having 1 to 22 carbon atoms, alkyl groups having 1 to 4 carbon atoms are preferred from the viewpoint of adsorption, more preferably methyl and ethyl groups, and particularly preferably methyl groups.

[0018] X is either an oxygen atom or NH. Q is an alkylene group having 1 to 6 carbon atoms. Of the alkylene groups having 1 to 6 carbon atoms, an alkylene group having 1 to 4 carbon atoms is preferred from the viewpoint of adsorption.

[0019] Z - It is a monovalent anion. Examples of monovalent anions include anions of inorganic acids and anions of organic acids. Examples of inorganic acids include hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid, and nitric acid. Examples of organic acids include sulfonic acids, carboxylic acids, and phosphonic acids. Examples of sulfonic acids include methylsulfonic acid, dodecylbenzenesulfonic acid, and naphthalenesulfonic acid. Examples of carboxylic acids include oxalic acid, acetic acid, and maleic acid. Examples of phosphonic acids include methylphosphonic acid and phenylphosphonic acid. - As for the anion represented by , from the viewpoint of cesium adsorption performance, the conjugate base of hydrochloric acid, the conjugate base of hydrobromic acid, or the conjugate base of sulfuric acid are preferred. - The anion represented by may be an anion introduced by a salt exchange reaction using Brønsted acid, or an anion generated by elimination from a quaternizing agent (such as methyl chloride or dimethyl sulfate).

[0020] Examples of cationic monomers (x1) represented by general formula (1) include (meth)acryloyloxyethyltrimethylammonium chloride (DAC) and methacryloyloxyethyltrimethylammonium chloride (DMC) and other (meth)acryloyloxyalkyltrialkylammonium salts; and (meth)acryloylaminoalkyltrialkylammonium chloride (DMAPAA) and [3-(methacryloylamino)propyl]trimethylammonium chloride (DMAPMA). Of these, (meth)acryloyloxyalkyltrialkylammonium salts and (meth)acryloylaminoalkyltrialkylammonium salts are preferred from the viewpoint of adsorption, and more preferably acryloyloxyethyltrimethylammonium chloride (DAC), methacryloyloxyethyltrimethylammonium chloride (DMC), (3-acrylamidopropyl)trimethylammonium chloride (DMAPAA), and [3-(methacryloylamino)propyl]trimethylammonium chloride (DMAPMA).

[0021] Other cationic monomers (x2) besides (x1) include (vinylbenzyl)trimethylammonium chloride (VBTAC) and allyltrimethylammonium chloride (TAAC).

[0022] The polymer may contain monomers other than the cationic monomer (x). Examples of monomers other than the cationic monomer (x) include acrylamide, methacrylamide, dimethyl(meth)acrylamide, diethyl(meth)acrylamide, isopropyl(meth)acrylamide, diacetone(meth)acrylamide, (meth)acryloylmorpholine, 2-hydroxyethyl(meth)acrylamide, hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, tetrahydrofurfuryl(meth)acrylate, phenoxyethyl(meth)acrylate, benzyl(meth)acrylate, (meth)acrylic acid, methyl(meth)acrylate, ethyl(meth)acrylate, butyl(meth)acrylate, and styrene. Among monomers other than the cationic monomer (x), those preferred from the viewpoint of adsorption are acrylamide, methacrylamide, dimethyl(meth)acrylamide, diethyl(meth)acrylamide, isopropyl(meth)acrylamide, diacetone(meth)acrylamide, (meth)acryloylmorpholine, and 2-hydroxyethyl(meth)acrylamide, and more preferably acrylamide and methacrylamide.

[0023] The content of the cationic monomer (x1) represented by general formula (1) is preferably 50% by weight or more, more preferably 80% by weight or more, and particularly preferably 90% by weight or more, based on the weight of the polymer, from the viewpoint of adsorption.

[0024] From the viewpoint of cesium adsorption, the π-electron density of the polymer is preferably 2 meq / g or less, more preferably 1 meq / g, particularly preferably 0.1 meq / g or less, and most preferably 0 meq / g, based on the weight of the polymer. In this specification, "π-electron density" is defined as the number of milliequivalents (meq / g) of aromatic hydrocarbon groups (e.g., phenyl group, benzyl group, naphthyl group, anthranyl group, etc.) having π electrons per gram of the polymer. The value of the π-electron density of the polymer can be determined, for example, according to the following formula (1). π electron density (meq / g) = 1,000 × number of aromatic hydrocarbon groups in the polymer per mole ÷ (formula weight or number-average molecular weight of the polymer) When the π electron density increases, the polymer (also called graft chain) becomes entangled through π-π interactions, reducing the spread of the polymer in water. When the spread of the polymer in water decreases, the frequency of contact between the supported cesium adsorbent and the cesium dissolved in the water decreases, and the cesium adsorption capacity decreases.

[0025] The polymer grafting rate is preferably 1 to 100%, and more preferably 10 to 50%, from the viewpoint of the physical properties (strength, elasticity, and durability) of the modified fibers. The graft rate of a polymer is the value obtained by dividing the weight difference between the fiber before graft polymerization and the modified fiber after graft polymerization by the weight of the fiber before graft polymerization, and can be calculated according to the following formula (3). Graft rate (%) = 100 × (M1 - M0) ÷ M0(3) M0: Weight of the fiber before graft polymerization M1: Weight of modified fibers after graft polymerization

[0026] From the viewpoint of cesium adsorption, the hydroxyl group density of the polymer is preferably 2 meq / g or less, more preferably 1 meq / g or less, particularly preferably 0.1 meq / g or less, and most preferably 0 meq / g (no hydroxyl groups) based on the weight of the polymer. In this specification, "hydroxyl group density" is defined as the number of milliequivalents of hydroxyl groups per gram of cationic (co)polymer (meq / g). The value of the hydroxyl group density of the cationic (co)polymer can be determined, for example, according to the following formula (1). Hydroxyl group density (meq / g) = 1,000 × Number of hydroxyl groups in a polymer per mole ÷ (Chemical formula weight or number-average molecular weight of the polymer) (1) When the hydroxyl group density increases, the polymer composed of cationic (co)polymers becomes entangled by hydrogen bonding, reducing the spread of the polymer in water. When the spread of the polymer in water decreases, the frequency of contact between the supported cesium adsorbent and the cesium dissolved in the water decreases, which may reduce the cesium adsorption capacity.

[0027] The cation charge density of the polymer is 2.0 to 5.5 meq / g, preferably 2.2 to 5.3 meq / g, based on the weight of the polymer. "Cation charge density" refers to the positive charge (N) per gram of the polymer. + It is defined as the number of milliequivalents (meq / g) of quaternary nitrogen atoms represented by . The value of the cation charge density of the polymer can be determined, for example, according to the following formula (2). Cation charge density (meq / g) = 1,000 × (number of quaternary nitrogen atoms per mole of polymer) ÷ (formula weight or number-average molecular weight of polymer) (2) If the cation charge density is less than 2.0 meq / g, the amount of cesium adsorbent that can be supported on the polymer decreases, resulting in a reduction in cesium adsorption capacity. If the cation charge density is greater than 5.5 meq / g, the polymer becomes rigid when cesium adsorbent is supported, resulting in a reduction in cesium adsorption capacity. The cation charge density of a polymer can be adjusted by controlling the type and content of the cationic monomer (x).

[0028] This paper describes a method for producing modified fibers in which polymers are bonded to fibers. When fibers are irradiated with ionizing radiation, radicals are generated on the surface and inside the fibers. When polymerizable monomers are brought into contact with these radicals, polymerizable monomers containing cationic monomers (x) undergo graft polymerization, using the generated radicals as a starting point, thereby obtaining modified fibers.

[0029] The ionizing radiation used for irradiation includes alpha rays, beta rays, gamma rays, electron beams, and neutron beams, but it is industrially preferable to use gamma rays and electron beams, which have the ability to penetrate from the surface to deeper parts of the fiber. There are no particular limitations on the irradiation conditions for radiation, but in order to obtain sufficient graft efficiency in the next step, it is preferable to use a deoxygenated state with a dose of 5 to 200 kGy, particularly 30 to 100 kGy. In this case, the oxygen concentration should be such that graft polymerization at the required polymerization rate is achieved, preferably an oxygen concentration of 1% or less, and more preferably an oxygen concentration of 100 ppm or less.

[0030] The cesium adsorbent in the present invention is not particularly limited as long as it adsorbs cesium, but examples include cesium-adsorbing complexes. Examples of cesium-adsorbing complexes include Prussian blue type complexes and phthalocyanine type complexes. As a cesium adsorbent, Prussian blue type complexes and phthalocyanine type complexes are preferred from the viewpoint of cesium adsorption, and Prussian blue type complexes are more preferred.

[0031] Prussian blue type complexes include, for example, those with general formula A xThe complex is represented by [B(CN)6]·zH2O (wherein A and B represent cations). Examples of cations B include metal ions such as vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, lanthanum, europium, gadolinium, lutetium, barium, strontium, and calcium. Examples of cations A include the metal ions listed above as cations B, as well as monovalent metal ions such as ammonium ions and potassium. These cations may be one or two or more. Specifically, examples include cobalt ferrocyanate, potassium ferrocyanide, iron ferrocyanide, and ammonium ferrocyanide. Of these, cobalt ferrocyanate (Co2[Fe(CN)6]) is preferred from the viewpoint of cesium adsorption capacity and cesium selectivity in the presence of impurities.

[0032] The average primary particle size of the Prussian blue-type complex is not particularly limited, but from the viewpoint of cesium adsorption capacity and processing suitability, it is presumed that 0.001 to 100 μm is preferred, 0.001 to 10 μm is more preferred, 0.001 to 1 μm is even more preferred, and 0.001 to 0.05 μm is even more preferred.

[0033] Examples of phthalocyanine-type complexes include copper phthalocyanine, chlorinated copper phthalocyanine, brominated chlorinated copper phthalocyanine, and aluminum phthalocyanine. More specifically, examples of copper phthalocyanine include Pigment Blue 15, Pigment Blue 15:3, Pigment Blue 76, Ingrain Blue 1, and Direct Blue 86. An example of chlorinated copper phthalocyanine is Pigment Green 7. An example of brominated chlorinated copper phthalocyanine is Pigment Green 58.

[0034] Since the above-mentioned cesium adsorbent is negatively charged, it is presumed that it can adsorb cesium by being fixed to the above-mentioned carrier.

[0035] <Method for measuring cesium (Cs) concentration> The water treatment material of the present invention exhibits excellent cesium adsorption performance. Furthermore, the cesium adsorption capacity in the present invention was confirmed by the following evaluation method. A removal system was constructed consisting of a 150L plastic tank, a pump, a pre-filter (PP wound-type filter, pore size 10μm), a 50φ acrylic column, and a 50L treated water tank. 200g of cesium adsorbent was cut into approximately 50mm lengths and packed into the tank. Next, an aqueous solution was prepared using cesium chloride to achieve a cesium concentration of 10mg / L. This cesium-containing water was passed through the pre-filter, cesium-adsorbent material, and treated water tank at a rate of approximately 40L / h using a pump. The cesium concentration in the treated water was measured by ICP-MS from the initial flow time to 1, 2, 3, and 3.7 hours later.

[0036] This specification discloses the following: (1) The present disclosure is a water treatment material comprising a cesium-adsorbing material consisting of a carrier and a cesium adsorbent supported on the carrier, wherein the carrier is a modified fiber to which a polymer containing a cationic monomer (x) bonded to the fiber is bonded, the cationic monomer (x) is a cationic monomer (x1) represented by general formula (1), and the cation charge density in the polymer containing the cationic monomer (x) is 2.0 to 5.5 meq / g based on the weight of the polymer. CH2=C(R 1 )-CO-XQN + (R 2 )(R 3 )(R 4 )·Z - (1) [In formula (1), R 1 R is a hydrogen atom or a methyl group. 2 ~R 4 Each of the following is independently a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, X is an oxygen atom or NH, Q is an alkylene group having 1 to 6 carbon atoms, Z - This represents a monovalent anion.

[0037] The present disclosure (2) is a water treatment material according to the present disclosure (1), wherein the carrier is a modified fiber in which a polymer containing a cationic monomer (x) as a constituent monomer is bonded to a fiber made of at least one selected from the group consisting of cellulose, polyester, polyamide, poly(meth)acrylic acid ester, polyvinyl chloride, polyvinylidene chloride, polyethylene, polypropylene, polyurethane, polyvinyl alcohol, phenolic resin, melamine resin, and epoxy resin.

[0038] Disclosure (3) is a water treatment material according to Disclosure (1) or (2), wherein the cesium adsorbent is a Prussian blue type complex.

[0039] (4) of this disclosure is a water treatment material according to any one of items (1) to (3) of this disclosure, wherein the cesium-adsorbing material contained in the water treatment material is a fiber made of the cesium-adsorbing material, a nonwoven fabric made using the fiber, a woven fabric made using the fiber, a twisted yarn made using the fiber, a non-porous membrane made of the cesium-adsorbing material, a porous membrane made of the cesium-adsorbing material, particles made of the cesium-adsorbing material, or a processed product thereof.

[0040] Next, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the examples shown below. [Examples]

[0041] The evaluation method for the water treatment material of the present invention in the examples and comparative examples is as follows.

[0042] <Manufacturing of water treatment materials> <Example 1> 500g of twisted yarn made of nylon (polyamide) fibers with a fiber diameter of approximately 35μm was placed in a polyethylene bag, and nitrogen purging was repeated three times by introducing nitrogen gas into the depressurized exhaust. This bag was then irradiated with 30kGy of gamma rays. After irradiation, the irradiated nylon fibers, still in the bag, were placed in a styrofoam box, and dry ice was added to cool them. On the other hand, acryloyloxyethyltrimethylammonium chloride (DAC) was dissolved in pure water to prepare 1 L of a 10 wt% aqueous solution. Nitrogen was bubbled through this solution to prepare a deoxygenated DAC aqueous solution. Irradiated nylon fibers, cooled in a styrofoam box, were placed in a glass ampoule. The ampoule was then vacuumed for 10 minutes using a vacuum pump to create a vacuum inside the ampoule. Deoxygenated DAC aqueous solution was then introduced into the ampoule using the vacuum. The ampoule was heated in a 40°C constant temperature water bath for 5 hours to perform graft polymerization and modify the nylon fibers. After polymerization, the modified nylon fibers were removed from the ampoule, washed three times with 50°C pure water, and then measured for weight after vacuum drying. From the weight increase rate, it was found that the DAC graft rate was 34%. After taking 1 g of fiber after vacuum drying, it was immersed in 100 ml of 5 wt% sodium hydroxide aqueous solution and stirred for 15 minutes. Then, the fiber was washed in a separate container with pure water until the pH test paper no longer showed acidity. In yet another container, the fiber was immersed in 100 ml of 2 wt% sodium chloride aqueous solution and stirred for 30 minutes. In yet another container, the fiber was stirred in pure water, and then this pure water was mixed with 100 ml of the used 2 wt% sodium chloride aqueous solution. The mixture was titrated with 0.05 M hydrochloric acid aqueous solution, and the neutral salt decomposition capacity was determined according to the following formula. The neutral salt decomposition capacity of the nylon fiber after graft polymerization was found to be 1.2 meq / g. Neutral salt decomposition capacity = 0.05 × V ÷ W (V: titration volume [mL], W: dry weight of fiber [g]) Next, the modified fibers were immersed in a 2% by weight aqueous solution of potassium ferrocyanate for 1 hour to adsorb ferrocyanate ions onto the fibers. These modified fibers, which had adsorbed ferrocyanate ions, were then immersed for 1 hour in a solution prepared to a concentration of 0.1 M cobalt chloride and 0.3 M potassium chloride. A cesium-adsorbing material supported by cobalt ferrocyanate was obtained. Fibers made from this cesium-adsorbing material were used as a water treatment material.

[0043] <Examples 2-8, Comparative Examples 1-4> A water treatment material was obtained in the same manner as in Example 1, except that the polymerizable monomers listed in Table 1 were used.

[0044] [Table 1]

[0045] The monomers listed in Table 1 are as follows: DAC: Acryloyloxyethyltrimethylammonium chloride DMC: Methacryloyloxyethyltrimethylammonium chloride DMAPAA: (3-acrylamidopropyl)trimethylammonium chloride DMAPMA: [3-(methacryloylamino)propyl]trimethylammonium chloride VBTAC: (Vinylbenzyl)trimethylammonium chloride TAAC: Allyltrimethylammonium chloride AAm: Acrylamide MAm: Methacrylamide St: Styrene

[0046] <Cesium Removal Test (Cesium Adsorption)> A removal system consisting of a 150L plastic tank, a pump, a pre-filter (PP wound-type filter, pore size 10μm), a 50mmφ acrylic column, and a 50L treated water tank was constructed. 200g of water treatment material was cut to a length of approximately 50mm and packed into the 50mmφ acrylic column. Next, an aqueous solution was prepared using cesium chloride to achieve a cesium concentration of 10mg / L. This cesium-containing aqueous solution was placed in the 150L plastic tank, and the liquid was passed through the pre-filter, the acrylic column filled with water treatment material, and the treated water tank at a flow rate of approximately 40L / h using a pump. The cesium (Cs) concentration in the treated water was measured using the method described above 1, 2, 3, and 3.7 hours after the start of flow, and evaluated according to the following evaluation criteria, as recorded in Table 1.

[0047] The evaluation criteria are as follows: Cesium concentrations in the treated water 1, 2, 3, and 3.7 hours after the start of liquid flow. ○: Cesium concentration less than 0.1 mg / L ×: Cesium concentration of 0.1 mg / L or higher

[0048] <Adsorbent shedding test> 250 ml of cesium chloride aqueous solution with a cesium concentration of 10 ppm was placed in a 500 ml beaker, and 10 g each of the water treatment materials obtained in Examples 1-8 and Comparative Examples 1-4 were added thereto. The mixture was then shaken at 50 rpm (rotary shaking incubator, Takasaki Scientific Instruments Co., Ltd. "TB-98") for 15 hours at 20°C. The solution after shaking was filtered by suction using a PTFE membrane filter (pore size 0.2 μm), and the mass of the sediment in the aqueous solution was measured. The sedimentation rate was calculated from the ratio of the filtered mass of sediment to the mass W0 before shaking using the following formula, and evaluated according to the evaluation criteria below, as shown in Table 1. Amount of adsorbent removed (%) = (Mass of removed material filtered (g)) / (Mass of water treatment material W0 (g) before shaking treatment) × 100

[0049] The evaluation criteria are as follows: ○: Dropout rate less than 0.1% ×: Dropout rate 0.1% or more

[0050] As is clear from Table 1, the cesium removal tests using the water treatment materials in Examples 1 to 8 all showed cesium concentrations of less than 0.1 mg / L, demonstrating that cesium could be removed solely by filtration without the need for complicated coagulation and sedimentation procedures. Furthermore, the turbidity and color measurements of the treated water according to the tap water testing method were 1 degree or less and 5 degrees or less, respectively, resulting in a clear liquid. Desorption of the adsorbent was also extremely minimal. Moreover, since the treatment material is made of organic material, it could be subjected to compression or incineration. On the other hand, the water treatment materials in Comparative Examples 1-4 had poor cesium adsorption properties, and the adsorbent was easily detached.

Claims

1. A water treatment material comprising a cesium-adsorbing material consisting of a carrier and a cesium adsorbent supported on the carrier, The carrier is a modified fiber in which a polymer containing a cationic monomer (x) as a constituent monomer is bonded to the fiber. The cationic monomer (x) is a cationic monomer (x1) represented by general formula (1), A water treatment material in which the cation charge density of a polymer containing a cationic monomer (x) is 2.0 to 5.5 meq / g based on the weight of the polymer. CH ２ =C(R １ )-CO-X-Q-N ＋ (R ２ )(R ３ )(R ４ )・Z － (1) [In formula (1), R １ is a hydrogen atom or a methyl group, R ２ to R ４ are each independently a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, X is an oxygen atom or NH, Q is an alkylene group having 1 to 6 carbon atoms, and Z － represents a monovalent anion.]

2. The water treatment material according to claim 1, wherein the carrier is a modified fiber in which a polymer containing a cationic monomer (x) as a constituent monomer is bonded to a fiber made of at least one selected from the group consisting of cellulose, polyester, polyamide, poly(meth)acrylic acid ester, polyvinyl chloride, polyvinylidene chloride, polyethylene, polypropylene, polyurethane, polyvinyl alcohol, phenolic resin, melamine resin, and epoxy resin.

3. The water treatment material according to claim 1 or 2, wherein the cesium adsorbent is a Prussian blue type complex.

4. The water treatment material according to claim 1 or 2, wherein the water treatment material is a fiber made of a cesium-adsorbing material, a nonwoven fabric made using the fiber, a woven fabric made using the fiber, a twisted yarn made using the fiber, a non-porous membrane made of a cesium-adsorbing material, a porous membrane made of a cesium-adsorbing material, particles made of a cesium-adsorbing material, or a processed product thereof.

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