WO2014010417A1 - Procédé de fabrication d'adsorbant de césium et adsorbant de césium - Google Patents

Procédé de fabrication d'adsorbant de césium et adsorbant de césium Download PDF

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WO2014010417A1
WO2014010417A1 PCT/JP2013/067498 JP2013067498W WO2014010417A1 WO 2014010417 A1 WO2014010417 A1 WO 2014010417A1 JP 2013067498 W JP2013067498 W JP 2013067498W WO 2014010417 A1 WO2014010417 A1 WO 2014010417A1
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ferrocyanide
water
cesium
compound
soluble
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Japanese (ja)
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平岡　秀樹
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東亞合成株式会社
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/04—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/0203—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of metals not provided for in B01J20/04
    • B01J20/0225—Compounds of Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt
    • B01J20/0229—Compounds of Fe
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
    • B01J20/103—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate comprising silica
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B01J20/3085—Chemical treatments not covered by groups B01J20/3007 - B01J20/3078
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/04—Treating liquids
    • G21F9/06—Processing
    • G21F9/12—Processing by absorption; by adsorption; by ion-exchange

Definitions

  • the present invention relates to a method for producing a cesium adsorbent and a cesium adsorbent. More specifically, it is an adsorbent that has a high cesium adsorption capacity and a small amount of cyanide elution, contains a large amount of cations other than cesium, and efficiently removes cesium from waste liquids with low cesium concentrations.
  • the present invention relates to a method for producing a cesium adsorbent.
  • Radioactive cesium is produced by a fission reaction such as uranium 235, but it is an alkali metal that has a long half-life and is easy to elute, so it is contained in various treatment liquids at nuclear facilities. It is known that cesium can be adsorbed and removed by using a specific zeolite when other cations do not coexist in the waste liquid containing cesium.
  • a poorly water-soluble ferrocyanide compound has excellent cesium adsorption ability as a means for removing radioactive cesium from a liquid in which other metal ions coexist, such as seawater.
  • a poorly water-soluble ferrocyanide compound is a fine powder and has a primary particle size of about 50 nm to 100 nm, so that when used as an adsorbent as it is, it is dispersed in water, so that it is difficult to recover the whole amount. It is difficult to use it as an adsorbing tower. Therefore, it has been studied to use a poorly water-soluble ferrocyanide compound supported on a substance having a porous structure.
  • Patent Document 1 describes the use of a combustible cesium adsorbent in which a poorly water-soluble ferrocyanide compound is deposited in the pores of activated carbon.
  • Patent Document 2 discloses a cesium adsorbent having high cesium adsorption capacity and carrying a copper salt-based poorly water-soluble hexacyanoiron (II) salt (also known as copper ferrocyanide) in the pores of a porous carrier.
  • II copper salt-based poorly water-soluble hexacyanoiron
  • Activated carbon loaded with metal compounds is useful if the amount of radioactive waste is small, but activated carbon loaded with ferrocyanide metal compounds, especially when adsorbing cesium contained in a large amount of cesium-containing water.
  • the amount of radioactive waste increases.
  • the ferrocyanide-supported porous resin in Patent Document 2 also known as copper hexacyanoferrate (II)
  • the proportion of copper ferrocyanide supported in the porous resin is small, and the radioactive waste is small. If it is useful, especially when a cesium is adsorbed for a large amount of processing liquid, there is a problem that radioactive waste increases for the same reason as described above.
  • the present inventors have proposed a cesium adsorbent that can be used as a filter medium by solidifying a poorly water-soluble ferrocyanide compound with a metal oxide as a binder.
  • the cesium adsorbent obtained by the methods of Patent Document 1 and Patent Document 2 has a content of poorly water-soluble ferrocyanide compound of only about several to no more than about 20% of the total weight of the adsorbent, In this method, the ratio of the poorly water-soluble ferrocyanide compound to the entire adsorbent can be easily increased to 50% or more, and the adsorption capacity can be significantly increased.
  • Ferrocyanide ions contain cyanide ions as ligands, and ferrocyanide ions may decompose in the environment to generate toxic free cyanide, and the emission concentration must be lowered.
  • the wastewater standard value for cyan is 1 mg / L as the total cyanide amount. Excess drainage cannot be discharged into the environment.
  • This cyanide is not limited to cyanide ions that are highly toxic per se, but also cyanides that exist as ligands in ferricyanides and ferricyanides that are oxidized by iron, the central metal. The water after adsorbing and removing cesium needs to have a total cyan density less than the reference value.
  • Patent Document 3 discloses adsorbing an ⁇ -oxycarboxylic acid such as citric acid or malic acid to a powder containing bitumen, which is an iron ferrocyanide pigment. It is described that bitumen fading can be suppressed.
  • the present inventors conducted an experiment by adsorbing these ⁇ -oxycarboxylic acids to a cesium adsorbent prepared using bitumen, which is a kind of poorly water-soluble ferrocyanide compound and manufactured as a blue pigment. As a result, there was no expected effect on suppression of ferrocyanide elution. From this, it can be said that even if this method is effective in preventing blue fading after being applied as a coloring pigment, it is not effective in an environment where there are many alkali metal ions such as seawater.
  • Non-Patent Document 1 Takeshita et al. Of Tokyo Institute of Technology disperse iron ferrocyanide in cesium-containing water, and then add a coagulating precipitant to coagulate and precipitate iron ferrocyanide adsorbed cesium, and then remove the precipitate.
  • a method for removing cesium has been reported (for example, Non-Patent Document 1).
  • polyaluminum chloride can be used as the coagulating precipitant, but it is only used as a coagulating precipitant that is generally known. Further, since the coagulating precipitant is added after ferrous ferrocyanide is put in water containing cesium and adsorbed with cesium, the effect as in the present invention cannot be expected.
  • the present invention provides a cesium adsorbent that can significantly reduce the elution of ferrocyanide ions when a cesium adsorbent containing a poorly water-soluble ferrocyanide compound is used to remove cesium.
  • An object is to provide a manufacturing method.
  • the present inventors brought a solid containing a poorly water-soluble ferrocyanide compound into contact with a treatment liquid containing an inorganic polymer flocculant such as polyaluminum chloride. After that, it is possible to suppress elution of ferrocyanide ions by further contact with a weak alkaline solution, or contact with a solution containing a surfactant in a solid containing a poorly water-soluble ferrocyanide compound, and further, these treatments. It has been found that a higher effect can be obtained by combining the methods, and the present invention has been completed.
  • the pH further becomes 7 It is characterized by contacting with 10 to 10 alkaline solutions.
  • the method for producing a cesium adsorbent according to claim 2 is characterized in that a treatment liquid containing a surfactant is brought into contact with a solid containing a poorly water-soluble ferrocyanide compound.
  • the method for producing a cesium adsorbent according to claim 3 is characterized by performing the following treatments (1) and (2) on a solid containing a poorly water-soluble ferrocyanide compound.
  • (1) After contacting with a treatment liquid containing an inorganic polymer flocculant, an alkaline solution having a pH of 7 to 10 is further contacted.
  • (2) Contact with a treatment solution containing a surfactant.
  • the method for producing a cesium adsorbent according to claim 4 is characterized in that the inorganic polymer flocculant immediately precipitates in an aqueous solution having a pH of 7 or more and a property that immediately precipitates when added to an aqueous solution of a water-soluble ferrocyanide.
  • the method for producing a cesium adsorbent according to claim 5 is characterized in that the inorganic polymer flocculant comprises at least one of polyaluminum chloride, polyiron sulfate, and polysilica iron. It is a manufacturing method of the cesium adsorbent in any one of Claim 3 or Claim 4.
  • the solid containing a poorly water-soluble ferrocyanide compound is composed of a poorly water-soluble ferrocyanide compound and a metal oxide, and at least the following (3), (4 The method for producing a cesium adsorbent according to any one of claims 1 to 6, wherein the cesium adsorbent is compounded by any one of methods (1) and (5). (3) Water difficulty in which particulate metal oxide and solvent are mixed with poorly water-soluble ferrocyanide compound, or dispersion of particulate metal oxide is mixed in poorly water-soluble ferrocyanide compound, and then the dispersion medium is volatilized and removed. A method of compounding a soluble ferrocyanide compound and a metal oxide.
  • a poorly water-soluble ferrocyanide metal compound and a metal oxide are mixed by mixing a poorly water-soluble ferrocyanide metal compound and an acidic catalyst solution, further mixing sodium silicate with this mixed solution to gel, and drying. How to composite.
  • a poorly water-soluble ferrocyanide compound and a metal oxide which react with a water-soluble ferrocyanide and a transition metal salt to precipitate and carry a poorly water-soluble ferrocyanide compound inside the pores of a porous metal oxide solid A method of compounding things.
  • the method for producing a cesium adsorbent according to claim 8 is a method in which a poorly water-soluble ferrocyanide compound and a metal oxide are compounded by the method of claim 7 and further crosslinked and cured by the method of (6) below.
  • ferrocyanide metal compound is ferric ferrocyanide, ferric ferrocyanide ammonium, ferric ferric sodium salt and ferric ferrocyanide.
  • the invention of claim 11 is a cesium adsorbent obtained by the production method according to any one of claims 1 to 10.
  • the cesium adsorbent obtained by the production method of the present invention is excellent in cesium adsorption performance and can remove cesium by a simple method. Furthermore, even if contaminated water containing cesium has a high pH like seawater and contains a large amount of cations such as alkali metals and alkaline earth metals, elution of ferrocyanide ions can be suppressed. Since many contaminated waters can be treated, radioactive waste generated by cesium adsorption can be reduced.
  • concentration in the cesium adsorption test liquid in Example 17 and Comparative Example 1 is shown.
  • the relationship between the initial cesium concentration and the iron detection concentration in Comparative Example 1 is shown.
  • the poorly water-soluble ferrocyanide compound in the present invention can be used without particular limitation as long as it is hardly soluble in water.
  • M represents a metal component and the like, and the ferrocyanide ion is a tetravalent anion, so that M and the ferrocyanide ion have the same valence.
  • M is composed of one or a plurality of cations, and when M is a plurality of cations, it may be two or more of the same cations, or may be two or more types of cations. .
  • ferrocyanide potassium ferrocyanide, sodium ferrocyanide, ammonium ferrocyanide, iron ferrocyanide, potassium ferrocyanide, sodium ferrocyanide, copper ferrocyanide, copper ferrocyanide, Cobalt ferrocyanide, potassium potassium ferrocyanide, cobalt sodium ferrocyanide, cobalt ammonium ferrocyanide, nickel ferrocyanide, nickel potassium ferrocyanide, nickel sodium ferrocyanide, nickel ammonium ferrocyanide, zinc ferrocyanide And zinc ferrocyanide, sodium zinc ferrocyanide, ammonium ammonium ferrocyanide, and the like.
  • the ferric ammonium ferrocyanide represented by this can be used especially preferably from the point which is easy to acquire.
  • the cobalt ferrocyanide represented by these is preferable in that it has a higher ability to selectively adsorb cesium than the ferrocyanide.
  • the cation and the anion complex ferrocyanide ion have the same valence of the cation and the anion. It is only necessary to exist in a proper ratio. When actually produced, the abundance ratio of two or more types of cations is not constant, and it is known that they are produced at various ratios.
  • the aforementioned nickel potassium ferrocyanide is typically represented by K 2 Ni [Fe (II) (CN) 6 ], but the ratio of potassium to nickel need not be strictly 2: 1,
  • the structure is represented by (4-2m) Ni m [Fe (II) (CN) 6 ]
  • m can be represented by 1 or more and 2 or less. If m is smaller than 1, it means that a part is present as water-soluble potassium ferrocyanide. Therefore, even if such a compound is mixed, m is 1 to 2 as a hardly soluble component in water. Needless to say.
  • the cesium adsorbent in the present invention contains a poorly water-soluble ferrocyanide compound, a finely powdered poorly water-soluble ferrocyanide compound together with a binder, and formed into a granular shape, in the pores of a porous carrier In which the water-soluble ferrocyanide and the transition metal salt are reacted to precipitate a poorly water-soluble ferrocyanide compound, inside the pores of the porous carrier, and in sheet-like porous bodies such as fiber cloth A solid-state material such as a form in which is attached can be used.
  • an organic substance such as a polymer can be used as the binder, but a metal oxide, glass,
  • Use of fine inorganic particles such as clay is preferable because it is easy to form a porous molded article having excellent water permeability and excellent adsorption performance.
  • These inorganic binders are kneaded with a fine powder of a poorly water-soluble ferrocyanide compound in a state dispersed in a solvent such as water, poured into a mold or the like, and heated as necessary to remove a solvent such as water. It is possible to mold by removing by volatilization.
  • the inorganic binder is a material that generates a strong binding force by being sintered or melted and integrated at a high temperature of usually 500 to 1000 ° C. or higher, but since ferrocyanide decomposes at a temperature lower than that, Such a sintering process cannot be applied.
  • the metal alkoxide can form a covalent bond with an OH group present on the surface of these inorganic particles by a condensation reaction, a chemical bond is formed at a lower temperature than the poorly water-soluble ferrocyanide compound decomposes, A strong molded body is obtained.
  • the fine particle inorganic binder can be used without any particular limitation, but a metal oxide having a particle diameter of 1 to 100 nm is preferable because of its excellent binding property to a ferrocyanide metal compound. Further, those having a hydroxyl group (hydroxy group) on the surface are preferable because crosslinking curing by dehydration reaction by heating or the like or crosslinking by condensation reaction by metal alkoxide can be expected. Specifically, a metal oxide having a titanol group, an aluminal group, or a silanol group, or a metal oxide having a hydroxyl group (hydroxy group) on the surface with fine particles made of titania, alumina, silica, and zirconia can be used.
  • colloidal material dispersed in water using water as a dispersion medium is preferable because it is easy to disperse and is easy to handle.
  • colloidal silica is the most typical, and is preferable because waste can be easily disposed of by vitrification of a remover that has adsorbed radioactive cesium.
  • the metal oxide when used in the form of fine particles, it is preferable to use a solvent such as water and mix it with a poorly water-soluble ferrocyanide compound.
  • metal oxides preferably used include colloidal silica in which silicic anhydride (silica fine particles) having a particle size of 5 to 30 nm is colloidally dispersed in water or an organic solvent.
  • a mold is preferred.
  • water-dispersed colloidal silica since a large number of hydroxyl groups are present on the surface of the silica fine particles, a strong molded body is obtained that is easily mixed with a poorly water-soluble ferrocyanide compound that is also hydrophilic.
  • the water-dispersed colloidal silica is divided into an acidic aqueous dispersion type and a basic aqueous dispersion type, both of which can be used.
  • the metal ferrocyanide compound can be used in a basic atmosphere with a pH exceeding 10 or an acidic atmosphere with a pH of 1 or less. It is preferable to use one having a pH in the range of 2 to 9 because it is easily decomposed. In addition, even if it is outside the preferable pH range, it can be used by adjusting the pH to a preferable range by adding an acid or a base.
  • a commercial product can be used as it is.
  • Snowtex O (trade name) manufactured by Nissan Chemical Industries, Ltd.
  • JGC Catalysts & Chemicals Cataloid SN (trade name) manufactured by Co., Ltd.
  • Snowtex C (trade name), Snowtex 30 (trade name) and Snowtex manufactured by Nissan Chemical Industries, Ltd. 40
  • the method for mixing the poorly water-soluble ferrocyanide compound and the metal oxide is not particularly limited, and a known mixing method can be used. Since it is desirable to mix as uniformly as possible, it is preferable to mix in advance using a kneader such as a kneader before molding. As a specific example, water or an organic solvent is added from a mixture obtained by mixing a poorly water-soluble ferrocyanide metal compound, metal oxide fine particles and / or a metal oxide dispersion and water or an organic solvent as necessary. An example of a method for removing the volatilization is illustrated. In the mixture obtained here, since one or both of the poorly water-soluble ferrocyanide compound and the metal oxide are not dispersed or dissolved again in water, destruction such as loss of shape does not occur in a large amount of processing waste liquid.
  • Patent Document 1 and Patent Document 2 disclose such methods.
  • the porous carrier that can be used in these methods include silica gel, porous alumina, and porous glass.
  • a method for forming the poorly water-soluble ferrocyanide compound fine particles with a metal oxide as a binder a method generally known as a method for producing silica gel can be used in addition to the above method. That is, it is a method of depositing silica gel by adding a catalyst such as sulfuric acid to a liquid containing sodium silicate. In this case, since the pH of the sodium silicate is high, the poorly water-soluble ferrocyanide compound is decomposed during the production by dispersing and mixing the poorly water-soluble ferrocyanide compound fine particles on the catalyst solution side and mixing with sodium silicate. Hard to do.
  • the ferrocyanide when supported on a sheet-like porous material such as cloth, the cloth is dipped in a dispersion of a poorly water-soluble ferrocyanide metal compound and then dried, as in the case of supporting the porous carrier.
  • a method of immersing in an aqueous solution of potassium ferrocyanide or the like and then immersing in an alcohol aqueous solution of a transition metal salt can be used.
  • the sheet-like porous material that can be used is preferably one having a hydrophilic property such as cotton cloth because its chemical structure has many polar groups having high affinity with the metal ferrocyanide.
  • the surface can be hydrophilized by ozone treatment, plasma treatment in the atmosphere, ultraviolet treatment in the atmosphere, corona discharge treatment in the atmosphere, or the like.
  • the cesium adsorbent in the present invention is preferably subjected to a treatment for reinforcement after molding a poorly water-soluble ferrocyanide compound with a binder or the like.
  • a method in which a poorly water-soluble ferrocyanide compound is molded into a solid state with a metal oxide or the like and then cured with alkoxysilane can be used.
  • the strength of the adsorbent in water is high, the content of the poorly water-soluble ferrocyanide compound, which is an active ingredient for cesium adsorption, can be increased, and a large amount of cesium can be adsorbed with a small amount of adsorbent. Most preferable from the viewpoint of being able to do.
  • the ratio of the metal ferrocyanide compound in the cesium adsorbent is preferably 50 to 95% by mass, more preferably 60 to 85% by mass.
  • metal oxides act as a binder for finely particulate water-insoluble ferrocyanide compounds and have the effect of improving shape retention when cesium adsorbents are immersed in water containing cesium.
  • the content of the metal oxide is preferably 5 to 50% by mass, more preferably 15 to 40% by mass.
  • other components can be added for the purpose of adjusting the fluidity during the forming process.
  • glass, silica, alumina, various clay minerals and flow modifiers, foaming agents, antifoaming agents, dispersing agents and the like are exemplified.
  • the cesium adsorbent in the present invention a material obtained by solidifying a poorly water-soluble ferrocyanide compound with a binder or supporting it on a porous sheet such as a porous carrier or cloth as described above is used.
  • a poorly water-soluble ferrocyanide compound is synthesized, primary particles are produced as fine particles having a size of several tens to several hundreds of nanometers. Once such fine particles are dispersed in water, it becomes very difficult to separate and recover, so it is necessary to facilitate separation of water and adsorbent.
  • a separation method using a filtration tower is known. For this reason, it is easy to adsorb and remove radioactive cesium dissolved in water by forming it into a shape suitable for filling the filtration tower.
  • Filtration towers are widely used as a means for removing impurities contained in liquids, such as in the production of drinking water, and generally known are those filled with sand, activated carbon or ion exchange resin.
  • the filling material to be filled in is required to have a large surface area and absorb a large amount of impurities, to have a low resistance when flowing liquid, and to be free from contamination by the filling material.
  • the poorly water-soluble ferrocyanide compound is produced as fine particles having a very small size, and there is no known method for increasing the crystal size to a size suitable as a filter medium. For this reason, it is not preferable to fill the filtration tower as it is because the resistance to liquid passage becomes too large and leakage of fine particles is liable to occur.
  • the particle size is Those having an average particle size of about 0.1 mm to 5 mm can be preferably used.
  • the particle size is designed taking into account various factors such as the length of the adsorption tower, the flow rate of the flowing liquid, the cross-sectional area, the concentration of cesium contained in the water contaminated by cesium, and the influence of coexisting substances, the particle size shown here It is not limited to the diameter.
  • the shape of the cesium adsorbent of the present invention may be formed into a cylindrical shape, a pipe shape, a spherical shape, or a honeycomb shape as necessary, and may be an amorphous shape such as sand instead of a fixed shape.
  • the poorly water-soluble ferrocyanide compound and the binder are mixed and molded, and then heated by a method such as ventilation drying.
  • the heating condition is not particularly limited as long as it is equal to or lower than the decomposition temperature of the metal ferrocyanide compound, but in order to sufficiently heat, for example, it is preferable to heat at a temperature of 120 ° C. to 150 ° C. for 2 hours to 3 hours.
  • colloidal silica is used as the binder, those heated at 120 ° C. to 150 ° C.
  • the particles are disintegrated, they are reinforced by crosslinking with metal alkoxide to improve water resistance, so depending on the size after disintegration, they can be used as filter media, but the heating temperature is too low. This is not preferable because it causes a problem that it becomes difficult to control the size of the formed grains.
  • a hard water-soluble ferrocyanide compound with a binder or when using a porous carrier such as silica gel carrying a poorly water-soluble ferrocyanide compound
  • a porous carrier such as silica gel carrying a poorly water-soluble ferrocyanide compound
  • metal alkoxides can also be bonded to each other by hydrolysis and condensation to form metal oxides, and since condensation reactions can occur between hydroxyl groups such as silanol groups and metal alkoxides, they can be chemically bonded. I guess that there is a function to combine particles.
  • a porous carrier such as silica gel has a remarkable reinforcing effect because the metal alkoxide penetrates into the inside and undergoes a crosslinking reaction.
  • a porous carrier such as silica gel
  • a well-known method is applicable.
  • the metal alkoxide examples include a lower alkoxide of a metal selected from Si, Al, Zr and Ti.
  • the lower alkoxide examples include methoxide, ethoxide, propoxide, butoxide and isomers thereof such as isopropoxide, sec-butoxide, t-butoxide and the like, and one or more of these can be used.
  • Specific examples of metal alkoxides include silicon tetraethoxide (ethyl silicate), silicon tetramethoxide (methyl silicate), silicon tetrabutoxide (butyl silicate), propyl silicate, aluminum triisopropoxide, zirconium tetrabutoxide, titanium tetraisooxide.
  • a propoxide etc. are mentioned.
  • silicon tetramethoxide and silicon tetramethoxide are preferable.
  • Such a partial hydrolyzate includes a partial hydrolyzate of tetramethoxysilane (trade name: methyl silicate 51, manufactured by Colcoat Co., Ltd.), a partial hydrolyzate of tetraethoxysilane (trade name: ethyl silicate 40, manufactured by Colcoat Co., Ltd.), etc.
  • a curing catalyst and water necessary for hydrolysis can be added to the alkoxysilane solution.
  • inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid
  • inorganic bases such as sodium hydroxide, ammonia, tetramethylammonium hydroxide and the like can be used.
  • an acid or base is used as a catalyst, the reaction of metal alkoxide is promoted and a crosslinking reaction can be caused at a lower temperature.
  • poorly water-soluble ferrocyanide is easily decomposed, and ferrocyanide ions are eluted.
  • the heating temperature can be increased or the heating time can be increased. It is preferable to carry out the condensation reaction by setting to
  • the heating condition is not particularly limited as long as it is equal to or lower than the decomposition temperature of the ferrocyanide compound, but it is preferable to heat at 100 to 150 ° C. for 2 to 3 hours, for example. At that time, it may be heated in an inert gas atmosphere so that the ferrocyanide is not oxidized.
  • a material formed into a granule or the like in order to apply a poorly water-soluble ferrocyanide compound or the like to a simple device such as a filtration tower is treated with a treatment liquid, so that the cesium adsorption performance is maintained.
  • the present invention provides a method for suppressing elution of a chemical compound. As one of the methods, there is a method in which an alkaline solution having a pH of 7 to 10 is further brought into contact with a treatment liquid containing an inorganic polymer flocculant.
  • a cesium adsorbent containing a poorly water-soluble ferrocyanide compound is pretreated by the method of the present invention with a liquid containing the inorganic polymer flocculant, ferrocyanide ions eluted during use for adsorption of cesium Can be reduced.
  • the compounds known as flocculants those that can achieve such an effect include the property of causing immediate precipitation in an aqueous solution having a pH of 7 or higher, and the immediate precipitation when added to an aqueous solution of a water-soluble ferrocyanide.
  • An inorganic polymer flocculant having the property of generating water is preferred.
  • Examples of the inorganic polymer flocculant exhibiting the above properties include polyaluminum chloride, polyiron sulfate, and polysilica iron.
  • the polyaluminum chloride is represented by the chemical formula [Al 2 (OH) n Cl 6-n ] m , where n is 1 to 5 and m is usually 10 or less.
  • Polyaluminum chloride which is usually used in the form of an aqueous solution or powder and is distributed as an industrial product, is a chemical that is mainly added to water containing suspended solids to coagulate and precipitate suspended solids to separate and purify wastewater. As widely used.
  • the polyaluminum chloride aqueous solution used for the purification of the waste water for example, as specified in Japanese Industrial Standard JIS K1475-1996, a 10 to 11% by mass value converted in terms of aluminum oxide content is used. ing.
  • a material formed into a granular form composed of a poorly water-soluble ferrocyanide compound and a metal oxide is treated with polyaluminum chloride, a material with about 10% by mass in terms of aluminum oxide content is used as it is. Then, since the cesium adsorption rate and the cesium adsorption amount decrease, it is preferable to dilute with water.
  • the cesium adsorption rate and adsorption Less decrease in amount is preferable. Furthermore, when diluted with water to an aluminum oxide content of 0.2 to 1% by mass, the decrease in the cesium adsorption rate and the amount of adsorption is reduced, and the effect of inhibiting ferrocyanide ion elution is high. More preferably, it is used.
  • Poly ferric sulfate is represented by [Fe 2 (OH) n ( SO 4) 3-n / 2] m, n is 2 greater than 1 or less, m is usually the compound of about 10. It is usually used in the form of an aqueous solution, and like polyaluminum chloride, it is widely used as a chemical for purifying wastewater by adding it to water containing suspended matter and coagulating and separating suspended matter to separate and separate it.
  • Polysilica iron is made by adding ferric chloride to polymerized silicic acid and coexisting with ferric ions.
  • An average molecular weight of about 500,000 is distributed as an aqueous solution, and it is distributed as a coagulation and precipitation agent like polyaluminum chloride. ing.
  • inorganic polymer flocculant used in the present invention when added to water in which a water-soluble ferrocyanide such as potassium ferrocyanide (also known as yellow blood salt) is dissolved, precipitation occurs immediately.
  • a water-soluble ferrocyanide such as potassium ferrocyanide (also known as yellow blood salt)
  • inorganic flocculants and aluminum sulfate generate precipitation at high pH, but when added to a water-soluble ferrocyanide aqueous solution, precipitation occurs immediately. The property which does not show was shown, and it was a grade which finally generate
  • These are well known as inorganic flocculants, but are not polymerized to have a high molecular weight. Further, in any case, the organic polymer flocculant does not cause precipitation.
  • a method of bringing a solid formed into a granule comprising a poorly water-soluble ferrocyanide compound and a metal oxide into contact with a treatment liquid containing an inorganic polymer flocculant used in the present invention is a necessary amount of an inorganic polymer flocculant aqueous solution.
  • the solid is immersed in an excess aqueous solution of an inorganic polymer flocculant, left for a while, and then filtered to remove excess inorganic
  • a method of discharging the molecular flocculant aqueous solution is preferable. When dipping, it may be stirred.
  • the inorganic polymer flocculant aqueous solution to be used a commercially available stock solution may be used as it is, but it is better to dilute with water. If the concentration is too high, the inorganic polymer flocculant enters too much into the solid consisting of the poorly water-soluble ferrocyanide metal compound and metal oxide, blocking the internal pores, and the cesium adsorption rate and adsorption capacity decrease, If it is too thin, the effect of inhibiting elution of ferrocyanide ions is weakened.
  • an aqueous solution having an Al 2 O 3 content of 10 to 11% by mass is mainly distributed in Japan.
  • polyferric sulfate 11 mass% aqueous solution with an iron content distribute
  • an aqueous solution (trade name PSI-025) having a silica / iron ratio of about 0.25 and an iron concentration of 6 to 6.3% by mass, or a silica / iron ratio of 0.5 and an iron concentration of 2.
  • a 5-2.7 mass% aqueous solution (trade name PSI-050) is in circulation. In either case, it is preferable to dilute with water 5 to 100 times, preferably 10 to 30 times.
  • the contact time is preferably about 10 minutes to 120 minutes, more preferably 30 minutes to 60 minutes. It is. The effect is observed even when contact is performed for less than 10 minutes, but the effect is not remarkable.
  • the temperature of the treatment liquid containing the inorganic polymer flocculant is preferably 40 ° C. or lower, more preferably 30 ° C. or lower. Treatment with heating at 50 ° C. or higher is not preferable because the elution amount of ferrocyanide ions increases.
  • an alkaline solution having a pH of 7 to 10 for the base treatment performed following the contact with the treatment liquid containing the inorganic polymer flocculant.
  • the reason is that when the pH exceeds 10, the poorly water-soluble ferrocyanide metal is decomposed and easily eluted as ferrocyanide ions.
  • An alkaline solution having a pH of 7 to 9 is preferred because elution of ferrocyanide is reduced.
  • the alkali is not particularly limited, and sodium hydroxide, potassium hydroxide, magnesium hydroxide, ammonia, organic amines, sodium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate and the like can be used.
  • sodium hydrogen carbonate is particularly preferable because the pH of the aqueous solution can be adjusted to 8 to 9 without strictly adjusting the concentration.
  • alkaline earth metal salts such as calcium salts and magnesium salts show alkalinity
  • the present inventors have examined that, in the presence of alkaline earth metal ions, the poorly water-soluble ferrocyanide tends to decompose. Since it has been found, it is preferable to use an alkali metal compound or an organic base.
  • a surfactant has a hydrophilic part and a hydrophobic part in one molecule, and is used in various applications such as a detergent, an emulsifier, a wetting agent, and an antifoaming agent.
  • the surfactant that can be used in the present invention is not particularly limited. However, when the type used for the cleaning agent is used, there is a drawback that bubbles are easily generated in the processing step and are very difficult to handle. Surfactants that are less likely to generate foam are preferably used for defoamers and wetting agents.
  • Air Products Japan's Dynol (trade name), Surfynol (trade name), Environment Gem ( An acetylenic diol skeleton, a derivative thereof, or a mixture thereof, such as (trade name) and Olfin (trade name) manufactured by Nissin Chemical Industry Co., Ltd. can be preferably used.
  • the contact method may be, for example, in a liquid in which a surfactant is dissolved or dispersed in water or a solvent.
  • a method of immersing a solid containing a soluble ferrocyanide compound, removing unnecessary surfactant solution or dispersion by filtration, and finally drying, or a solid containing a poorly water-soluble ferrocyanide compound It can be carried out by a simple method of washing with a solution or dispersion of Further, the temperature of the surfactant aqueous solution or dispersion is not limited as in the treatment liquid used in the treatment method using the inorganic polymer flocculant, and is preferably applied in the step of hydrolyzing the remaining alkoxysilane. The effect can be obtained even at a moderate temperature.
  • the present invention provides a ferrocyanide that maintains a cesium adsorption performance by treating a solid material containing a poorly water-soluble metal ferrocyanide compound with a treatment agent as described above, so as to be applied to a simple apparatus such as a filtration tower.
  • a method for suppressing elution of fluoride ions is provided.
  • a method therefor a first method in which a treatment with a treatment liquid containing the inorganic polymer flocculant and a treatment with a weak alkaline solution are used together, and a second method in which a treatment with a treatment liquid containing a surfactant is performed are found.
  • a combination of these two methods is preferable because the effect of suppressing the elution of ferrocyanide ions is further enhanced.
  • the first method and the second method are more effective than the case where each of them is performed first, but it is better to perform the second method after performing the first method first. A high synergistic effect is obtained, which is preferable.
  • the present invention provides a method for producing a cesium adsorbent that suppresses elution of ferrocyanide while maintaining cesium adsorption performance.
  • the cesium adsorbent subjected to the ferrocyanide ion elution prevention treatment can be directly packed in the adsorption tower, and by supplying contaminated water containing cesium to the adsorption tower filled with the cesium adsorbent and bringing it into contact with the cesium adsorbent.
  • the cesium is removed from the contaminated water.
  • the conditions for bringing the cesium adsorbent into contact with the contaminated water are not particularly limited, but conditions such as the adsorbent filling amount and the contaminated water flow rate can be appropriately selected according to the cesium concentration in the contaminated water.
  • ⁇ Granulation example 1 800 g ferric ferrocyanide ammonium (trade name: MILORI BLUE 905, manufactured by Dainichi Seika Kogyo Co., Ltd.) and 1000 g colloidal silica dispersion (trade name: Snowtex O, manufactured by Nissan Chemical Industries, Ltd.) (200 g as solid content) They were mixed with a table kneader and kneaded for 10 minutes. The mixture obtained by kneading was poured into a stainless steel tray and spread to a thickness of about 5 mm. This was heated in a draft dryer at 70 ° C. for 1 hour, followed by heating at 130 ° C.
  • a granulated product 2 is obtained in the same manner as in Granulation Example 1 except that 96 g of water is added to a solution composed of 500 g of methyl silicate (trade name: Methyl silicate 51, manufactured by Colcoat Co., Ltd.) and 125 g of methanol and stirred. It was. In this case, water does not completely dissolve, but the granulated product obtained in this mixed solution is immersed for 2 hours, then the excess solution is removed by filtration, and the granulated product is impregnated with the solution Was again heated at 120 ° C. for 3 hours with a ventilating dryer to obtain a granulated product 2.
  • methyl silicate trade name: Methyl silicate 51, manufactured by Colcoat Co., Ltd.
  • Granulation Example 3 Granulation Example 1 except that ferric ferrocyanide (made by Alfa Aeser, USA, chemical formula Fe (III) 4 [Fe (II) (CN) 6 ] 3 ) was used instead of ferric ferric ammonium The granulated product obtained in the same manner is designated as granulated product 3.
  • potassium ferrocyanide trihydrate also known as potassium hexacyanoferrate (II) trihydrate
  • potassium ferrocyanide trihydrate also known as potassium hexacyanoferrate (II) trihydrate, manufactured by Wako Pure Chemical Industries, Ltd.
  • potassium ferrocyanide trihydrate also known as potassium hexacyanoferrate (II) trihydrate, manufactured by Wako Pure Chemical Industries, Ltd.
  • Example 1 50 g of the granulated product 1 and 60 g of water were put into a polyethylene bottle and left in an oven maintained at 60 ° C. for 2 hours to hydrolyze the remaining alkoxy groups. Next, the granulated product in the bottle was taken out on a 100-mesh polypropylene net, and the granulated product wrapped in the net was immersed in tap water and shaken several times to remove it from the water and washed three times. The granulated product immediately after washing is put into a polyethylene bottle, and 60 g of a solution obtained by diluting a commercially available polyaluminum chloride aqueous solution (containing 10% by mass as the aluminum oxide content) 10 times with water is added at room temperature.
  • the granulated product in the bottle is taken out on a 100-mesh polypropylene net, and the granulated product wrapped in the net is immersed in a 1% by mass aqueous sodium hydrogen carbonate solution having a pH of 8.5 at 25 ° C. for 1 hour. Retained.
  • the net was taken out from the aqueous sodium hydrogen carbonate solution, dipped in tap water, moved up and down several times in the water, and then removed from the water three times for washing. Finally, this granulated product was put in a glass beaker and dried at 120 ° C. for 2 hours to obtain a cesium adsorbent.
  • ferrocyanide When ferrocyanide is decomposed, two types of ions are generated, elution as iron (III) ions and elution as ferrocyan ions containing iron (II). This shows that elution of ferrocyanic ions, which are ions, could also be suppressed.
  • Examples 2, 3, and 4 Except that the dilution ratio of a commercially available aqueous solution of polyaluminum chloride (containing aluminum oxide content of 10% by mass) with water was 20 times in Example 2, 50 times in Example 3, and 100 times in Example 4. A cesium adsorbent was obtained in the same manner as in Example 1. Each of these adsorbents was subjected to the same cesium adsorption test as in Example 1, and as a result, the cesium removal rates after immersion for 24 hours were all 90% or more.
  • the concentration of iron contained in the water after the test was 0.59 ppm in Example 2, 0.64 ppm in Example 3, and 0.74 ppm in Example 4, and the detection of iron compared to Comparative Examples 1, 2, and 3 A dose reduction effect was observed.
  • the dilution rate it was found that the effect was reduced as the dilution was performed, and the effect was extremely reduced when diluted to a dilution rate higher than 100 times, in other words, less than 0.1% in terms of aluminum oxide content.
  • Examples 5 and 6 A commercially available aqueous solution of polyaluminum chloride (containing 10% by mass as the aluminum oxide content) has a dilution ratio of 10 times with water, and the time for immersing the granulated product in this liquid is 3 minutes in Example 5, and Example 6 Then, a cesium adsorbent was obtained in the same manner as in Example 1 except that the time was 30 minutes. Each of these adsorbents was subjected to the same cesium adsorption test as in Example 1, and as a result, the cesium removal rates after immersion for 24 hours were all 90% or more.
  • the concentration of iron contained in the water after the test was 0.95 ppm in Example 5 and 0.71 ppm in Example 6, and an effect of reducing the elution amount of iron was recognized as compared with Comparative Examples 1, 2, and 3. It was. In order to obtain a remarkable effect, it was found that the immersion time is 30 minutes or more, and in order to obtain a further effect, 60 minutes or more is required.
  • Examples 7, 8, and 9 After immersing the granulated product in the polyaluminum chloride aqueous solution, the time for immersing in the 1% by mass aqueous sodium hydrogen carbonate solution is 3 minutes in Example 7, 30 minutes in Example 8, 120 minutes in Example 9, and the others Obtained a cesium adsorbent in the same manner as in Example 1. Each of these adsorbents was subjected to the same cesium adsorption test as in Example 1, and as a result, the cesium removal rates after immersion for 24 hours were all 90% or more.
  • the iron concentration in the water after the test was 1.0 ppm in Example 7, 0.80 ppm in Example 8, and 0.54 ppm in Example 9.
  • the immersion time when immersed in an aqueous sodium bicarbonate solution after treatment with an aqueous solution of polyaluminum chloride is effective from about 30 minutes, and even higher effects are obtained at 60 minutes, but immersion at 60 minutes and 120 minutes. Since the results of (2) did not change so much, it was found that about 60 minutes of immersion was suitable for obtaining the maximum effect.
  • Example 10 After immersing the granulated material in an aqueous polyaluminum chloride solution and immersing it in a 1% by weight sodium bicarbonate aqueous solution for 60 minutes, the granulated material is immersed in tap water in a state of being wrapped in a 100 mesh polypropylene net. A method of removing the water from the water after raising and lowering the net several times in the water was repeated three times, and a cesium adsorbent was obtained in the same manner as in Example 1 except for the other conditions. As a result of conducting the cesium adsorption test similar to Example 1 about this adsorbent, the cesium removal rate after being immersed for 24 hours was 90% or more.
  • the iron concentration in the water after the test was 0.54 ppm. This result was equivalent to the result of Example 1 in which water washing was not performed before immersion in a 1% by mass aqueous sodium hydrogen carbonate solution.
  • Example 1 In the case of not washing with water after treatment with an aqueous solution of polyaluminum chloride such as in Example 1, many white precipitates of polyaluminum chloride are generated in the treatment liquid due to the increase in pH in the treatment step with 1% by mass sodium bicarbonate. However, in Example 10, such a precipitate was not generated. From this, the effect obtained by the present invention does not occur when the precipitate of polyaluminum chloride exists separately from the granulated product, but by the polyaluminum chloride strongly adsorbed inside the granulated product. It is thought to occur.
  • Example 11 a polyethoxylate of 2,5,8,11-tetramethyl-6-dodecin-5,8-diol sold for use as a wetting agent (trade name Dynol 604, manufactured by Air Products Japan Co., Ltd.) was used.
  • Example 12 sodium alkyldiphenyl ether disulfonate (trade name Perex SS, manufactured by Kao Corporation) sold for use as an emulsifier was diluted with water to a concentration of 0.1% by mass and used.
  • Example 13 an acetylenic diol compound (trade name Envirogem AD01, manufactured by Air Products Japan Co., Ltd.) sold for use as an antifoaming agent was diluted with water to a concentration of 0.1% by mass.
  • Example 14 an ethylene oxide adduct of acetylene glycol, propylene glycol, and a nonionic surfactant that were sold for use as a wetting agent were blended (Nissin Chemical Industry Co., Ltd., trade name Olphine EXP.4123) with a concentration of 1 It was diluted with water so as to have a mass%.
  • Example 14 Each of these adsorbents was subjected to a cesium adsorption test in the same manner as in Example 1. As a result, all the cesium removal rates after immersion for 24 hours were 90% or more.
  • the concentration of iron contained in the water after the test was 0.67 ppm in Example 11, 0.70 ppm in Example 12, 0.64 ppm in Example 13, and 0.44 ppm in Example 14. From these results, it was found that treatment with an aqueous surfactant solution or an aqueous dispersion also has an effect of suppressing elution of ferrocyanide ions.
  • the surfactants used in the antifoaming agents and wetting agents used in Examples 11, 13, and 14 were easy to clean because the aqueous solution hardly foamed during the process.
  • the anionic surfactant used in Example 12 was easy to generate bubbles.
  • the surfactant used in Example 14 was easily soluble in water, it could be dissolved in water even at a concentration of 1% by mass, and the effect of inhibiting elution of ferrocyanide was high.
  • Example 15 50 g of granulated product 1 and 60 g of water were put in a polyethylene bottle and left in an oven maintained at 60 ° C. for 2 hours. Next, the granulated product in the bottle was taken out on a 100-mesh polypropylene net, and the granulated product wrapped with the net was immersed in tap water and moved up and down several times to wash it out three times. Next, the granulated product immediately after washing with water is wrapped in a net and immersed in the same surfactant aqueous dispersion as in Example 13, the net is raised and lowered several times, and the whole net is pulled up. After the step of washing with tap water, the cesium adsorbent was prepared in the same manner as in Example 13.
  • Example 16 50 g of granulated product 1 and 60 g of the same surfactant aqueous dispersion as in Example 13 were placed in a polyethylene bottle and left in an oven maintained at 60 ° C. for 2 hours. Next, the granulated product in the bottle was taken out on a 100-mesh polypropylene net, and the granulated product wrapped with the net was immersed in tap water and moved up and down several times to wash it out three times. Finally, this granulated product was put in a glass beaker and dried at 120 ° C. for 2 hours to obtain a cesium adsorbent. The adsorbent was subjected to the same cesium adsorption test as in Example 1.
  • the cesium removal rate after immersion for 24 hours was 90% or more.
  • the iron concentration in the water after the test was 0.67 ppm. From this result, it was found that the step of treating with the surfactant can be performed simultaneously with the step of hydrolyzing the remaining alkoxysilane by immersing the granulated product 1 in 60 ° C. water.
  • Example 17 a combination of a method of treating with polyaluminum chloride followed by an aqueous sodium hydrogen carbonate solution and a method of treating with a surfactant was examined.
  • a treatment process using a polyaluminum chloride aqueous solution and then an aqueous sodium hydrogen carbonate solution was performed in the same process as in Example 1, and the first cleaning liquid was used in Example 13 among the three water washing processes.
  • a surfactant aqueous dispersion finally, it was dried at 120 ° C. for 2 hours to obtain a cesium adsorbent.
  • Example 18 the steps up to the step of treating with the surfactant dispersion are the same as those in Example 13, and then the granulated product is immersed in a polyaluminum chloride aqueous solution before drying and then dried.
  • the cesium adsorbent was prepared in the same manner as in No. 1.
  • Example 19 the granulated product 1 was treated in the process of Example 18, immersed in an aqueous sodium hydrogen carbonate solution, and then washed with water three times. As an activator aqueous dispersion, finally, it was dried at 120 ° C. for 2 hours to obtain a cesium adsorbent.
  • Example 19 Each of these adsorbents was subjected to the same cesium adsorption test as in Example 1, and as a result, the cesium removal rates after immersion for 24 hours were all 90% or more.
  • the concentration of iron contained in the water after the test was 0.39 ppm in Example 17, 0.51 ppm in Example 18, and 0.34 ppm in Example 19. From these results, when combining the treatment with the polyaluminum chloride aqueous solution and the treatment with the surfactant, it is most effective to perform the treatment with the surfactant after performing the treatment with the polyaluminum chloride aqueous solution and the sodium hydrogen carbonate aqueous solution. was found to be obtained.
  • Example 17 which was treated in the process of the present invention, the amount of ferrocyanide ions eluted was smaller than that in Comparative Example 1 in which treatment was not performed, and in Comparative Example 1, if the pH was high, ferrocyanide In Example 17, the concentration slightly increases at a higher pH, but the increase in concentration is extremely small compared to Comparative Example 1, and the treatment method of the present invention is effective over a wide pH range. Was found to be obtained.
  • Example 20 A cesium adsorbent was obtained in the same manner as in Example 1 except that the granulated product 1 used was changed to the granulated product 2. As a result of conducting the cesium adsorption test similar to Example 1 about this adsorbent, the cesium removal rate after being immersed for 24 hours was 90% or more. The concentration of iron contained in the water after the test is as low as 0.09 ppm. Even if the granulated product 2 in which the elution amount of iron is suppressed by increasing the concentration of methyl silicate compared to the granulated product 1 is still used, It was shown to increase the elution suppression effect of.
  • Example 21 A cesium adsorbent was obtained in the same manner as in Example 17 except that the granulated product 1 used was changed to the granulated product 2. As a result of conducting the cesium adsorption test similar to Example 1 about this adsorbent, the cesium removal rate after being immersed for 24 hours was 90% or more. The concentration of iron contained in the water after the test is as low as 0.06 ppm, and even when it becomes difficult to elute iron by using the granulated product 2, it is treated with polyaluminum chloride and sodium bicarbonate and with a surfactant. A synergistic effect of treatment could be observed.
  • Example 21 50 g of the cesium adsorbent obtained in Example 21 was packed in a glass column for a liquid passing experiment having an inner diameter of 3 cm, and artificial seawater adjusted to a cesium concentration of 0.01 ppm or 10 ppm was added from the top of the column to 6.7 ml / Table 1 and Table 2 together with the results of Comparative Example 7 show the cesium removal rate and the iron concentration obtained by analyzing the water flowing through the adsorbent layer and flowing out from the lower part of the column. Summarized in When the cesium concentration was 10 ppm, the iron concentration in both Example 21 and Comparative Example 7 remained low, and the amount of cyan was measured even if the total amount of detected iron was included in the ferrocyanide ion.
  • the cesium adsorption performance when the cesium concentration of the test solution is 0.01 ppm, the measurement limit is 0.001 ppm, and thus the adsorption rate is 90% or more. However, when compared with a solution having a cesium concentration of 10 ppm, The cesium removal rate by carrying out the method is the same in both Examples and Comparative Examples, and it can be seen that the cesium adsorption performance is not lowered by the method of the present invention.
  • Examples 22, 23, 24, and 25 Granules used are the same as in Example 1 except that Granule 3 is used in Example 22, Granule 4 in Example 23, Granule 5 in Example 24, and Granule 6 in Example 25.
  • the cesium adsorbent was obtained by the method. Each of these adsorbents was subjected to the same cesium adsorption test as in Example 1. As a result, the cesium removal rate after immersion for 24 hours was 90% or more.
  • the concentration of iron in the water after the test was 0.33 ppm in Example 22, 0.51 ppm in Example 23, 0.32 ppm in Example 24, and 0.28 ppm in Example 25. Compared to Comparative Examples 8, 9, 10, and 11 using the corresponding ferrocyanide, the detected iron concentration was lower.
  • Example 26 In 20 liters of 4N sulfuric acid, 216 g of ferric ferrocyanide (reagent made by ACROS) is dispersed, and 20 liters of sodium silicate (SiO 2 / Na 2 O ratio 3.3) silica concentration of 18% by mass is added. In addition, a silica hydrosol was produced by mixing and reacting, and then this was allowed to stand for 1 hour to obtain a gelled silica hydrogel. This was washed with water to remove sodium sulfate, and then 28% by mass aqueous ammonia was added to adjust the pH to 8.0, followed by aging at 80 ° C. for 12 hours. Furthermore, after drying at 120 ° C.
  • a cesium adsorbent was prepared by performing a hot water treatment at 60 ° C. and a treatment with a polyaluminum chloride and an aqueous sodium hydrogen carbonate solution in the same manner as in Example 1. did.
  • the adsorbent was subjected to the same cesium adsorption test as in Example 1, and as a result, the cesium removal rate after immersion for 24 hours was 90% or more.
  • the iron concentration in the water after the test was 0.38 ppm. It was found that the iron concentration was lower than that of Comparative Example 12 where the treatment according to the present invention was not performed, and the elution amount of ferrocyanide was reduced.
  • a poorly water-soluble ferrocyanide compound was supported on silica gel according to the method described in Japanese Patent Application Laid-Open No. 11-76807, which is Patent Document 2, and ferrocyanide elution suppression treatment was performed by the method of the present invention.
  • About 200 g of amorphous silica gel of about 2 to 3 mm in diameter (silica gel ID type: pore volume 0.95 ml, manufactured by Aichi Silica Industry Co., Ltd.) was weighed into an Erlenmeyer flask and then mixed with hexacyanoiron (II) A potassium acid aqueous solution (concentration: 22.7% by volume) was dropped to make the whole slightly wet.
  • the treating agent collapsed to a size of about 0.1 to 1 mm, and classification by sieving was not performed.
  • 19.2 g of water was added to a solution consisting of 100 g of methyl silicate (trade name: Methyl silicate 51, manufactured by Colcoat Co., Ltd.) and 100 g of methanol, and the resulting solution of potassium hexacyanoferrate (II) with copper potassium was added.
  • methyl silicate trade name: Methyl silicate 51, manufactured by Colcoat Co., Ltd.
  • methanol 100 g of methanol
  • this silicate-treated cesium adsorbent was used in place of the granulated product 1, it was treated with polyaluminum chloride and an aqueous sodium hydrogen carbonate solution in the same manner as in Example 1 to obtain a cesium adsorbent.
  • the adsorbent was subjected to the same cesium adsorption test as in Example 1, and as a result, the cesium removal rate after immersion for 24 hours was 90% or more.
  • the iron concentration in the water after the test was 1.4 ppm.
  • Example 29 60 g of a solution obtained by diluting commercially available polysilica iron (iron content 5 mass%, liquid specific gravity (20 ° C.) 1.14, trade name PSI-025 manufactured by Kosumi Kogyo Co., Ltd.) 10 times with water was used. In addition, each was left at room temperature for 1 hour. Next, the granulated product in the bottle is taken out on a 100 mesh polypropylene net, and the granulated product wrapped in the net is immersed in a 1% by mass sodium bicarbonate aqueous solution having a pH of 8.5 at 25 ° C. Held for hours.
  • commercially available polysilica iron iron content 5 mass%, liquid specific gravity (20 ° C.) 1.14, trade name PSI-025 manufactured by Kosumi Kogyo Co., Ltd.
  • the concentration of iron contained in the water after the test was 2.7 ppm in Example 28 and 2.7 ppm in Example 29, both of which were high, but polyiron sulfate and polysilica iron contained iron ions in the flocculant. Because it contains a large amount, it is not known whether or not the elution of ferrocyanide is reduced in the quantitative result of iron alone. Therefore, when ferrocyanide ions are quantified and compared with Example 1 and Comparative Example 1, the results are shown in Table 3. It was found that the same effect as the polyaluminum chloride used in 1 was obtained. From this, it was found that both the polyferric sulfate and the polysilica iron can significantly suppress the amount of cyanide detected as a result of combining treatment with an aqueous sodium hydrogen carbonate solution.
  • Example 17 As a result of conducting the cesium adsorption test similar to Example 1 about this adsorbent, the cesium removal rate after being immersed for 24 hours was 90% or more. The iron concentration in the water after the test was 1.1 ppm. Further, as described in Example 17, a cesium adsorption test was conducted from artificial seawater having a cesium concentration of 0.01 ppm adjusted to pH 4 to 9 using sodium hydroxide and hydrochloric acid, and eluted in the test solution after 24 hours. As a result of quantification of ferrocyanide ions, as shown in FIG. 1, the higher the pH, the more ferrocyanide was eluted during the adsorption test, and it was found that the effect of pH was greater than in Example 17. It was.
  • the iron concentration after 24 hours was 1.1 ppm when the cesium concentration in seawater was 0 ppm.
  • the cesium adsorbent using the poorly water-soluble ferrocyanide compound is excellent in the ability to selectively adsorb cesium even in the presence of salt such as seawater, but it is a contamination subject to cesium adsorption removal. It was found that the elution amount of ferrocyanide increased depending on the water condition. That is, it was found that the elution of ferrocyanide may increase when the salt coexists, when the pH is high, or when the cesium concentration is low.
  • the granulated product in the bottle is taken out on a 100 mesh polypropylene net, and the granulated product wrapped in the net is immersed in tap water and shaken several times to remove it from the water and wash it three times. did. Finally, this granulated product was put in a glass beaker and dried at 120 ° C. for 2 hours to obtain a cesium adsorbent. As a result of conducting the cesium adsorption test similar to Example 1 about this adsorbent, the cesium removal rate after being immersed for 24 hours was 90% or more. The iron concentration in the water after the test was 1.1 ppm.
  • the granulated product immediately after washing is put in a polyethylene bottle, 60 g of a 1% by mass aqueous sodium hydrogen carbonate solution is added thereto, and left at room temperature for 1 hour, and then the granulated product in the bottle is taken out on a 100 mesh polypropylene net, A method of immersing the granulated material wrapped in the net in tap water and shaking it several times to remove it from the water was repeated 3 times for washing. Finally, this granulated product was put in a glass beaker and dried at 120 ° C. for 2 hours to obtain a cesium adsorbent.
  • the ⁇ -oxycarboxylic acid described in Patent Document 3 as having an effect on inhibiting fading of bitumen (iron ferrocyanide), the granulated product immediately after washing is put in a polyethylene bottle.
  • the concentration of iron contained in the water after the test is 1.8 ppm, and it can be said that aluminum sulfate does not have an effect of suppressing elution of ferrocyanide ions even if it is an aluminum salt like polyaluminum chloride.
  • ⁇ Comparative Example 12> In 20 liters of 4N sulfuric acid, 216 g of ferric ferrocyanide (reagent made by ACROS) is dispersed, and 20 liters of sodium silicate (SiO 2 / Na 2 O ratio 3.3) silica concentration of 18% by mass is added. In addition, a silica hydrosol was produced by mixing and reacting, and then this was allowed to stand for 1 hour to obtain a gelled silica hydrogel. This was washed with water to remove sodium sulfate, and then 28% by mass aqueous ammonia was added to adjust the pH to 8.0, followed by aging at 80 ° C. for 12 hours. Furthermore, after drying at 120 ° C.
  • Example 27 the silica gel was loaded with potassium hexacyanoferrate (II) and treated with a methyl silicate solution, and then heated at 120 ° C. for 3 hours until the methyl silicate was condensed. It was put in a plastic bottle, water was added until the water surface was above the support, and the mixture was left in an oven maintained at 60 ° C. for 2 hours to hydrolyze the remaining alkoxy groups. Next, the granulated product in the bottle was taken out on a 100-mesh polypropylene net, and the granulated product wrapped in the net was immersed in tap water and shaken several times to remove it from the water and washed three times. Finally, it was dried at 120 ° C.
  • II potassium hexacyanoferrate
  • Example 1 except that aluminum chloride (TK floc, manufactured by Taki Chemical Co., Ltd., about 9% aqueous solution as Al 2 O 3 ) was diluted 10 times with water instead of the polyaluminum chloride aqueous solution. Thus, a cesium adsorbent was obtained. As a result of conducting the cesium adsorption test similar to Example 1 about this adsorbent, the cesium removal rate after being immersed for 24 hours was 90% or more. The concentration of iron contained in the water after the test was 2.3 ppm, and it was found that the flocculant, which is an inorganic component but not high molecular weight, has no effect of inhibiting elution of ferrocyanide ions.
  • TK floc manufactured by Taki Chemical Co., Ltd., about 9% aqueous solution as Al 2 O 3
  • Example 15 The same procedure as in Example 1 was used except that an organic polymer flocculant (manufactured by MT Aquapolymer Co., Ltd., trade name Acofloc 110L) was used instead of the polyaluminum chloride aqueous solution diluted to 0.01 mass% with water. Thus, a cesium adsorbent was obtained. As a result of conducting the cesium adsorption test similar to Example 1 about this adsorbent, the cesium removal rate after being immersed for 24 hours was 90% or more. The concentration of iron contained in the water after the test was 2.1 ppm, and it was found that the organic polymer flocculant had no effect of inhibiting ferrocyanide ion elution.
  • an organic polymer flocculant manufactured by MT Aquapolymer Co., Ltd., trade name Acofloc 110L
  • ⁇ Evaluation method Preparation of artificial seawater containing cesium Artificial seawater element (Nippon Pharmaceutical Co., Ltd., trade name: Daigo Artificial Seawater SP) and ultrapure water device (Advantech Toyo Co., Ltd.) so that Cs concentration is 0.01 ppm or 10 ppm. It adjusted using the ultrapure water obtained using company brand name: RFU554CA), and simulated cesium pollution seawater was adjusted.
  • an ICP emission analyzer (trade name, CIROS-120, manufactured by Spectro Co., Ltd.)
  • an analytical solution was prepared by diluting a 100 ppm iron standard solution (manufactured by Wako Pure Chemical Industries, Ltd.) with ultrapure water.
  • a calibration curve was obtained as a 1, 0.5, 1 ppm concentration standard solution, and the iron concentration of the sample was quantified.
  • the absorbance at a wavelength of 720 nm was measured using a UV-VIS spectrophotometer (V-550 manufactured by JASCO Corporation), and compared with a calibration curve prepared in advance using an aqueous potassium ferrocyanide solution, ferrocyanide ions The concentration was quantified.
  • This method is a colorimetric determination method based on the following non-patent document 2, but according to the following non-patent document 3, the ferricyanide ion in which the central metal of the complex is oxidized is also a ferrocyanide ion. Since similar absorbance is shown, it has been reported that they cannot be distinguished from each other.
  • Non-Patent Document 2 is an attached test method in the notice of the food health department manager issued on July 12, 2002, from Eishoku No. 071/2001.
  • Non-Patent Document 3 is Mori, Nishioka, Yamashita, Nozaki, Tsukamoto, Kagawa Prefectural Environmental Health Research Center Bulletin No. 2 p72-74 (2003).

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Abstract

L'invention a pour but de proposer un procédé de fabrication d'un adsorbant de césium n'ayant pas de précipité de ferrocyanure même lorsqu'un adsorbant de césium contenant un ferrocyanure ayant une performance élevée d'adsorption de césium entre en contact avec une eau contenant du sel contaminée ayant une faible concentration en ions césium. A cet effet, l'invention concerne un procédé de fabrication d'un adsorbant de césium caractérisé en ce qu'il amène un solide contenant un composé métallique de ferrocyanure faiblement soluble dans l'eau à être d'abord mis en contact avec un fluide de traitement contenant un réactif de floculation polymère inorganique, puis avec une solution alcaline ayant un pH de 7-10 et/ou avec un fluide de traitement contenant un tensio-actif.
PCT/JP2013/067498 2012-07-10 2013-06-26 Procédé de fabrication d'adsorbant de césium et adsorbant de césium WO2014010417A1 (fr)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016014568A (ja) * 2014-07-01 2016-01-28 丸善薬品産業株式会社 放射性セシウム吸着材およびそれを用いた放射性汚染水の浄化方法
JP2016057287A (ja) * 2014-09-05 2016-04-21 行政院原子能委員會核能研究所 放射性核種の顆粒化無機吸着剤の製造方法
JP2016102053A (ja) * 2014-11-14 2016-06-02 東ソー株式会社 シリコチタネート成形体
CN111681797A (zh) * 2020-04-30 2020-09-18 中国辐射防护研究院 一种小型核设施退役现场放射性废水处理方法
WO2022102448A1 (fr) 2020-11-10 2022-05-19 国立研究開発法人産業技術総合研究所 Adsorbant granulé et son procédé de production

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JPS6243519B2 (fr) * 1979-12-06 1987-09-14 Hitachi Ltd
JPS62266499A (ja) * 1986-05-15 1987-11-19 株式会社東芝 放射性廃液の処理方法
JPH04361198A (ja) * 1991-06-07 1992-12-14 Power Reactor & Nuclear Fuel Dev Corp 塩共存放射性廃液の処理方法
JPH05317697A (ja) * 1991-03-29 1993-12-03 Agency Of Ind Science & Technol 硝酸含有水溶液中のセシウムの分離方法
JP2001514060A (ja) * 1997-08-27 2001-09-11 ミネソタ マイニング アンド マニュファクチャリング カンパニー 金属イオン吸着体、その製造方法および使用
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JP2012251987A (ja) * 2011-05-06 2012-12-20 Dainichiseika Color & Chem Mfg Co Ltd セシウム除去材

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Publication number Priority date Publication date Assignee Title
JPS6243519B2 (fr) * 1979-12-06 1987-09-14 Hitachi Ltd
JPS59174556A (ja) * 1983-03-23 1984-10-03 水澤化学工業株式会社 非収縮性水硬性セメント組成物
JPS62266499A (ja) * 1986-05-15 1987-11-19 株式会社東芝 放射性廃液の処理方法
JPH05317697A (ja) * 1991-03-29 1993-12-03 Agency Of Ind Science & Technol 硝酸含有水溶液中のセシウムの分離方法
JPH04361198A (ja) * 1991-06-07 1992-12-14 Power Reactor & Nuclear Fuel Dev Corp 塩共存放射性廃液の処理方法
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JP2012251987A (ja) * 2011-05-06 2012-12-20 Dainichiseika Color & Chem Mfg Co Ltd セシウム除去材

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016014568A (ja) * 2014-07-01 2016-01-28 丸善薬品産業株式会社 放射性セシウム吸着材およびそれを用いた放射性汚染水の浄化方法
JP2016057287A (ja) * 2014-09-05 2016-04-21 行政院原子能委員會核能研究所 放射性核種の顆粒化無機吸着剤の製造方法
JP2016102053A (ja) * 2014-11-14 2016-06-02 東ソー株式会社 シリコチタネート成形体
CN111681797A (zh) * 2020-04-30 2020-09-18 中国辐射防护研究院 一种小型核设施退役现场放射性废水处理方法
WO2022102448A1 (fr) 2020-11-10 2022-05-19 国立研究開発法人産業技術総合研究所 Adsorbant granulé et son procédé de production
JP2022076717A (ja) * 2020-11-10 2022-05-20 国立研究開発法人産業技術総合研究所 造粒吸着材及びその製造方法

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