JP2017187501A - Cesium adsorbent, method for manufacturing the same, and environmental treatment method using the same - Google Patents
Cesium adsorbent, method for manufacturing the same, and environmental treatment method using the same Download PDFInfo
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本発明は、セシウムを効率良く吸着し不溶化できる吸着材とその製造方法、この吸着材を用いた環境処理方法に関する。 The present invention relates to an adsorbent capable of efficiently adsorbing and insolubilizing cesium, a production method thereof, and an environmental treatment method using the adsorbent.
原子炉から排出される放射性廃棄物処理について、従来より、様々な方法が開発されてきたが、２０１１年の東日本大震災によって発生した、福島原子力発電所の爆発事故以来、環境中に飛散した放射性物質が大きな社会問題となり、その除染技術が求められている。例えば、放射性物質の中でも、半減期の長い放射性セシウムの除染には、水酸化鉄等の鉄化合物を用いる技術（特許文献１）、酸化鉄及びフェロシアン化アルカリ金属塩を吸着材に用いる技術（特許文献２）、酸化鉄、群青及び高分子化合物を吸着材に用いる技術（特許文献３）等が提案されている。 Various methods have been developed for the treatment of radioactive waste discharged from nuclear reactors. However, radioactive materials that have been scattered in the environment since the 2011 Fukushima nuclear power plant explosion occurred due to the Great East Japan Earthquake. Is a major social problem, and its decontamination technology is required. For example, among radioactive substances, for decontamination of radioactive cesium having a long half-life, a technique using an iron compound such as iron hydroxide (Patent Document 1), a technique using iron oxide and an alkali metal ferrocyanide as an adsorbent (Patent Document 2), a technique of using iron oxide, ultramarine, and a polymer compound as an adsorbent (Patent Document 3) has been proposed.
これらの従来技術より、一層優れた放射性セシウムの吸着能力を有する吸着材が求められている。 From these prior arts, there is a demand for an adsorbent having even better radiocesium adsorption capability.
本発明者らは、鋭意研究を重ねた結果、ケイ素を含有する鉄酸化物は、セシウムの吸着能力が優れ、吸着したセシウムを高度に不溶化でき、そうすると、当然のこととして、放射性セシウムの吸着能力が優れ、吸着した放射性セシウムを高度に不溶化できることを見出して本発明を完成した。 As a result of intensive research, the present inventors have found that iron-containing oxides containing silicon have excellent cesium adsorption ability and can highly insolubilize adsorbed cesium, and as a matter of course, the adsorption ability of radioactive cesium. And the present invention was completed by finding that the adsorbed radioactive cesium can be highly insolubilized.
即ち、本発明は、（１）ケイ素を含有する鉄酸化物を含むことを特徴とするセシウム吸着材であり、（２）鉄化合物とケイ素化合物とを媒液中で中和し酸化することを特徴とするセシウム吸着材の製造方法であり、（３）セシウムを含む環境中に当該セシウム吸着材を投入してセシウムを吸着させることを特徴とする環境処理方法である。 That is, the present invention is (1) a cesium adsorbent comprising an iron oxide containing silicon, and (2) neutralizing and oxidizing an iron compound and a silicon compound in a liquid medium. A method for producing a cesium adsorbent characterized in that (3) the environmental treatment method is characterized in that the cesium adsorbent is introduced into an environment containing cesium to adsorb cesium.
本発明の吸着材は、セシウム、放射性セシウム等の吸着能力が高く、特に放射性セシウムで汚染された水、土壌等を効果的に除染できる。従来のセシウム吸着材はナトリウムなどの夾雑イオンが存在すると、浄化対象のセシウムの吸着能力が低下することが知られているが、本発明の吸着材は夾雑イオンが存在しても優れた吸着能力を発揮する。 The adsorbent of the present invention has a high adsorption capacity for cesium, radioactive cesium and the like, and in particular, can effectively decontaminate water, soil and the like contaminated with radioactive cesium. Conventional cesium adsorbents are known to have reduced cesium adsorption capacity when contaminated ions such as sodium are present, but the adsorbent of the present invention has excellent adsorption capacity even in the presence of contaminated ions. Demonstrate.
本発明はセシウム吸着材であって、ケイ素を含有する鉄酸化物を含むことを特徴とする。本発明の吸着材はセシウム、放射性セシウム等の吸着能力が優れているので、放射性セシウムで汚染された水、土壌等の環境の除染に有用である。
ケイ素を含有する鉄酸化物の様態としては、（イ）鉄とケイ素の複合酸化物、（ロ）鉄酸化物とケイ素酸化物の混合物等が挙げられる。鉄とケイ素の複合酸化物は、鉄とケイ素と酸素から構成されるものであれば特に限定されず、同様に、鉄酸化物は、鉄と酸素から構成されるものであれば特に限定されず、ケイ素酸化物は、ケイ素と酸素から構成されるものであれば、特に限定されない。
（ロ）の様態には、鉄酸化物とケイ素酸化物の一様な混合物及び一様ではない混合物の双方がふくまれ、一様ではない混合物としては、例えば、鉄酸化物の表面等の一部にケイ素酸化物が偏在しているものが挙げられる。
The present invention is a cesium adsorbent, characterized by containing an iron oxide containing silicon. Since the adsorbent of the present invention has an excellent ability to adsorb cesium, radioactive cesium and the like, it is useful for decontamination of the environment such as water and soil contaminated with radioactive cesium.
Examples of the form of the iron oxide containing silicon include (a) a composite oxide of iron and silicon, (b) a mixture of iron oxide and silicon oxide, and the like. The composite oxide of iron and silicon is not particularly limited as long as it is composed of iron, silicon and oxygen. Similarly, the iron oxide is not particularly limited as long as it is composed of iron and oxygen. The silicon oxide is not particularly limited as long as it is composed of silicon and oxygen.
The mode (b) includes both uniform and non-uniform mixtures of iron oxide and silicon oxide. Examples of non-uniform mixtures include, for example, the surface of iron oxide. Examples thereof include those in which silicon oxide is unevenly distributed.
上記（イ）（ロ）以外の様態として、（ハ）コア部の表面にシェル部を有するコア・シェル構造を成し、シェル部が鉄とケイ素の複合酸化物であるか、又は、鉄酸化物とケイ素酸化物との混合物であるものが挙げられる。
コア部の部材は、環境に二次的な汚染が生じないようなものであれば、鉄酸化物、ケイ素酸化物、硫酸カルシウム、活性炭、ゼオライト、タルク等制限は無く、中でも鉄酸化物が好ましい。鉄酸化物は前記と同様、鉄と酸素から構成されるものであればよく、化学組成がＦｅＯ、Ｆｅ３Ｏ４、Ｆｅ２Ｏ３、過還元マグネタイトＦｅＯｘ（１．０＜ｘ＜１．３３）、ベルトライドＦｅＯｘ（１．３３＜ｘ＜１．５）、ＦｅＯＨ、ＦｅＯＯＨ、Ｆｅ（ＯＨ）２等のいずれの酸化物も用いることができる。コア部とシェル部の鉄酸化物は同じであっても、異なっていてもよい。また、シェル部はコア部の全体を被覆するものであっても、一部を被覆するものであってもよい。
As modes other than (a) and (b) above, (c) a core-shell structure having a shell part on the surface of the core part, and the shell part is a complex oxide of iron and silicon, or iron oxidation The thing which is a mixture of a thing and a silicon oxide is mentioned.
The core member is not limited to iron oxide, silicon oxide, calcium sulfate, activated carbon, zeolite, talc, and the like, as long as secondary contamination does not occur in the environment. Among them, iron oxide is preferable. . The iron oxide may be composed of iron and oxygen as described above, and the chemical composition is FeO, Fe 3 O 4 , Fe 2 O 3 , overreduced magnetite FeO x (1.0 <x <1. 33), any oxide such as belt ride FeO x (1.33 <x <1.5), FeOH, FeOOH, Fe (OH) 2, etc. can be used. The iron oxides in the core part and the shell part may be the same or different. Further, the shell portion may cover the entire core portion or a portion thereof.
様態（イ）、(ロ)のケイ素含有量、または、様態（ハ）のシェル部のケイ素含有量は、Ｆｅ／Ｓｉで表される鉄酸化物中の鉄とのモル比で、１／０．１〜１／１０．０の範囲であれば、セシウムの吸着能力が一層高くなるので好ましく、１／０．１〜１／５．０の範囲が更に好ましい。ケイ素を含有する鉄酸化物（以下、ケイ素含有鉄酸化物という場合がある）の形状は、球状、塊状等の等方性形状、針状、板状等の異方性形状等制限を受けず、いずれの形状でもよく、ＢＥＴ法による比表面積が１０〜１００ｍ２／ｇの範囲にあれば好ましい。 The silicon content of the mode (b) or (b) or the silicon content of the shell part of the mode (c) is 1/0 in terms of a molar ratio with iron in the iron oxide represented by Fe / Si. The range of 0.1 to 1 / 10.0 is preferable because the adsorption ability of cesium is further increased, and the range of 1 / 0.1 to 1 / 5.0 is more preferable. The shape of silicon-containing iron oxides (hereinafter sometimes referred to as silicon-containing iron oxides) is not limited by isotropic shapes such as spherical and lump shapes, and anisotropic shapes such as needles and plates. Any shape may be sufficient, and it is preferable if the specific surface area by BET method exists in the range of 10-100 m < 2 > / g.
鉄酸化物には、詳細には、様態（イ）、(ロ)の鉄酸化物や、様態（ハ）のシェル部の鉄酸化物には、ケイ素以外の無機元素、例えば、アルミニウム、マグネシウム、マンガン等が含まれていても良く、特にアルミニウムは、セシウムの吸着能力を向上させる効果が高く好ましい。ケイ素以外の無機元素の含有量は、アルミニウムであれば、Ｆｅ／Ａｌで表される鉄酸化物中の鉄とのモル比で、１／０．００５〜１／２．０の範囲が好ましい。
更に、様態(イ)、（ロ）における鉄酸化物、及び、様態（ハ）におけるシェル部の鉄酸化物に磁着性を付与するとセシウムを吸着させた後、磁別によって分離できる。様態（ハ）において、シェル部及びコア部の双方に鉄酸化物に用いた場合はコア部またはシェル部の少なくとも一方の鉄酸化物に磁着性を付与すれば磁別によって分離できる。
In detail, the iron oxide includes, in particular, the iron oxides of the modes (A) and (B) and the iron oxide of the shell part of the mode (C), inorganic elements other than silicon, such as aluminum, magnesium, Manganese or the like may be contained, and aluminum is particularly preferable because of its high effect of improving the adsorption ability of cesium. If the content of inorganic elements other than silicon is aluminum, the molar ratio with iron in the iron oxide represented by Fe / Al is preferably in the range of 1 / 0.005 to 1 / 2.0.
Further, when magnetic adhesion is imparted to the iron oxide in the modes (A) and (B) and the iron oxide in the shell portion in the mode (C), it can be separated by magnetic separation after adsorbing cesium. In the aspect (c), when iron oxide is used for both the shell part and the core part, it can be separated by magnetic separation if magnetic adhesion is imparted to at least one iron oxide of the core part or the shell part.
本発明のセシウム吸着材には、ケイ素含有鉄水酸化物以外にも、必要に応じて、(a)他の吸着材（活性炭、ゼオライト、キレート樹脂等）、(b)粘土鉱物（ベントナイト、タルク、クレー等）、(c)有機高分子（アニオン系有機高分子（ポリアクリル酸ソーダ、アクリル酸−アクリル酸エステル共重合体、アクリル酸ソーダ−アクリルアミド共重合体、カルボキシメチルセルロースソーダ塩、デンプン−アクリル酸−アクリル酸ソーダ共重合体、酢酸ビニル−マレイン酸ソーダ共重合体等）、非イオン系有機高分子（ポリアクリルアミド、アルキルセルロース、ポリエチレンオキサイド等）等）、(d)固化材（セメント、石灰等）及び固化遅延剤（クエン酸等）、(e)分散剤等が配合されていてもよい。 In addition to the silicon-containing iron hydroxide, the cesium adsorbent of the present invention includes (a) other adsorbents (activated carbon, zeolite, chelate resin, etc.), (b) clay minerals (bentonite, talc, as necessary) , Clay), (c) organic polymer (anionic organic polymer (polyacrylic acid soda, acrylic acid-acrylic acid ester copolymer, sodium acrylate-acrylamide copolymer, carboxymethylcellulose soda salt, starch-acrylic) Acid-sodium acrylate copolymer, vinyl acetate-sodium maleate copolymer, etc.), nonionic organic polymers (polyacrylamide, alkyl cellulose, polyethylene oxide, etc.), (d) solidifying material (cement, lime) Etc.) and a solidification retarder (citric acid etc.), (e) a dispersant, etc. may be blended.
次に、本発明は、セシウム吸着材の製造方法であって、鉄化合物とケイ素化合物とを媒液中で中和し酸化することを特徴とする。様態（イ）のケイ素含有鉄酸化物は、（i）鉄化合物とケイ素化合物を混合した後、中和剤を添加して中和し酸化するか、又は、（ii）ケイ素化合物を中和剤として用いて、鉄化合物とケイ素化合物とを中和反応させ、中和し酸化することで得られる。一方、様態（ロ）では、(iii)鉄化合物を中和し酸化後、ケイ素化合物を中和し酸化するか、または、（iv）鉄化合物を中和し、ケイ素化合物を中和した後、酸化することで得られ、中和剤の添加は、鉄化合物の添加後やケイ素化合物の添加後に行うことも、鉄化合物、ケイ素化合物と同時に平行添加することもできる。更に、様態（ハ）では、コア部となる基材の存在下で、鉄化合物とケイ素化合物を中和し酸化して、コア部の表面に、ケイ素を含有の鉄酸化物を含むシェル部を形成する。酸化は中和前、中和中、中和後のいずれのタイミングで行ってもよい。
鉄化合物、ケイ素化合物の中和方法は、所望するコア部の様態に応じて、（ｉ）〜（iv）のいずれかを選択する。様態（ハ）でコア部に鉄酸化物を用いる場合は、予め調製した鉄酸化物を用いても良く、あるいは、鉄化合物溶液の一部を中和、酸化して生成させた鉄酸化物をコア部として、引き続き（ｉ）〜（iv）の方法を適用してもよい。
Next, the present invention is a method for producing a cesium adsorbent, characterized in that an iron compound and a silicon compound are neutralized and oxidized in a liquid medium. The silicon-containing iron oxide of the mode (I) is either (i) mixed with an iron compound and a silicon compound and then neutralized by adding a neutralizing agent, or (ii) the silicon compound is neutralized. It is obtained by neutralizing the iron compound and the silicon compound, neutralizing and oxidizing. On the other hand, in the embodiment (b), (iii) after neutralizing and oxidizing the iron compound, neutralizing and oxidizing the silicon compound, or (iv) neutralizing the iron compound and neutralizing the silicon compound, The neutralizing agent can be added after the addition of the iron compound or the silicon compound, or can be added simultaneously with the iron compound and the silicon compound. Further, in the aspect (c), in the presence of the base material to be the core part, the iron compound and the silicon compound are neutralized and oxidized, and the shell part containing silicon-containing iron oxide is formed on the surface of the core part. Form. The oxidation may be performed at any timing before, during or after neutralization.
As a method for neutralizing the iron compound and the silicon compound, any one of (i) to (iv) is selected according to the desired state of the core part. When iron oxide is used for the core in the embodiment (c), a pre-prepared iron oxide may be used, or an iron oxide produced by neutralizing and oxidizing part of the iron compound solution may be used. You may apply the method of (i)-(iv) continuously as a core part.
中和ｐＨは、(i)、(ii)の方法であれば、３．０〜７．０の範囲が好ましく、５．０〜７．０の範囲が更に好ましく、(iii)、（iv）の方法であれば、鉄化合物、ケイ素化合物の好ましい中和ｐＨは、それぞれ７．０〜１０．０の範囲、４．０〜７．０の範囲である。酸化は、中和剤の添加前、添加中あるいは添加後の媒液中に、酸化剤を投入して行う。中和及び酸化時の温度は、２５〜８０℃の範囲が好ましい。鉄酸化物の酸化数は、酸化還元電位の測定により、酸化率を制御することで調整できる。アルミニウム、マンガン、マグネシウム等の、ケイ素以外の無機元素を含有させる場合は、例えば、鉄化合物の中和後で、ケイ素化合物の中和前に無機元素の化合物を添加する等して、（i）〜（iv）の方法に応じ、適当なタイミングで、当該無機元素化合物を中和し酸化する。 The neutralization pH is preferably in the range of 3.0 to 7.0, more preferably in the range of 5.0 to 7.0 in the methods (i) and (ii), and (iii) and (iv) If it is the method of this, the preferable neutralization pH of an iron compound and a silicon compound is the range of 7.0-10.0, and the range of 4.0-7.0, respectively. Oxidation is performed by adding an oxidizing agent into a liquid medium before, during or after the addition of the neutralizing agent. The temperature during neutralization and oxidation is preferably in the range of 25 to 80 ° C. The oxidation number of the iron oxide can be adjusted by controlling the oxidation rate by measuring the oxidation-reduction potential. In the case of containing an inorganic element other than silicon, such as aluminum, manganese, magnesium, etc., for example, by adding an inorganic element compound after neutralization of the iron compound and before neutralization of the silicon compound, (i) The inorganic element compound is neutralized and oxidized at an appropriate timing according to the methods (iv) to (iv).
（i）、(iii)、（iv）の方法で中和に用いる中和剤としては、例えば、水酸化ナトリウム、水酸化カリウム等のアルカリ金属の水酸化物、炭酸ナトリウム等のアルカリ金属の炭酸塩、アンモニウムガス、アンモニア水、炭酸アンモニウム等のアンモニウム化合物等の公知の塩基性化合物、及び、塩酸、硫酸、硝酸、有機酸等の公知の酸性化合物を用いることができる。
また、酸化剤としては、空気、酸素、オゾン等の酸化性ガスや、過酸化水素等の酸化性化合物を用いることができ、特に、空気は経済的で取り扱い易く、工業的に有利である。
鉄化合物としては硫酸鉄、塩化鉄等が、ケイ素化合物としては、ケイ酸ナトリウム、ケイ酸カリウム等が挙げられる。硫酸法酸化チタンの製造工程で副生する硫酸には、鉄成分として硫酸鉄が含まれているので、この副生硫酸を鉄化合物を含む媒液とし、ケイ素化合物を添加して用いると、低コストで有害物質吸着材を得ることができ、副生硫酸の処理・再利用にも寄与できる。媒液には、水等の水系媒液を用いるのが工業的に好ましく、前記のように鉄化合物を含む副生硫酸であってもよい。
Examples of the neutralizing agent used for neutralization by the methods (i), (iii), and (iv) include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and alkali metal carbonates such as sodium carbonate. Known basic compounds such as salts, ammonium gas, aqueous ammonia, ammonium compounds such as ammonium carbonate, and known acidic compounds such as hydrochloric acid, sulfuric acid, nitric acid, and organic acids can be used.
As the oxidant, an oxidizing gas such as air, oxygen, ozone, or an oxidizing compound such as hydrogen peroxide can be used. In particular, air is economical and easy to handle and is industrially advantageous.
Examples of the iron compound include iron sulfate and iron chloride, and examples of the silicon compound include sodium silicate and potassium silicate. Sulfuric acid produced as a by-product in the manufacturing process of sulfuric acid method titanium oxide contains iron sulfate as an iron component. Therefore, when this by-product sulfuric acid is used as a liquid medium containing an iron compound and a silicon compound is added, A hazardous substance adsorbent can be obtained at a low cost and can contribute to the treatment and reuse of by-product sulfuric acid. It is industrially preferable to use an aqueous medium such as water as the medium, and it may be a by-product sulfuric acid containing an iron compound as described above.
ケイ素含有鉄酸化物を生成させた後、固液分離してセシウム吸着材を得る。固液分離後は、必要に応じて、乾燥し、乾式粉砕する。固液分離には、例えば、フィルタープレス、ロールプレス等を用いることができる。乾燥には、例えば、バンド式ヒーター、バッチ式ヒーター等を用いることができる。乾式粉砕には、例えば、ハンマーミル、ピンミル等の衝撃粉砕機、解砕機等に摩砕粉砕機、ジェットミル等の気流粉砕機、スプレードライヤー等の噴霧乾燥機等を用いることができる。 After producing a silicon-containing iron oxide, solid-liquid separation is performed to obtain a cesium adsorbent. After solid-liquid separation, if necessary, dry and dry pulverize. For solid-liquid separation, for example, a filter press, a roll press, or the like can be used. For example, a band heater, a batch heater, or the like can be used for drying. For the dry pulverization, for example, an impact pulverizer such as a hammer mill or a pin mill, a pulverizer or the like, a grinding pulverizer, an airflow pulverizer such as a jet mill, or a spray dryer such as a spray dryer can be used.
また、本発明は環境処理方法であって、セシウムを含む環境中に前記セシウム吸着材を投入してセシウムを吸着させることを特徴とする。水や土壌の環境中に含まれるセシウムを吸着させるには、水処理、土壌処理等で用いられている公知の方法を用いることができる。例えば、水処理では、本発明のセシウム吸着材をセシウムを含む水に投入し、セシウムを吸着不溶化させた後、濾別すればよい。あるいは本発明のセシウム吸着材を処理塔に充填したり、フィルターに担持させて用いることもできる。地下水の処理では、例えば、土壌中に本発明のセシウム吸着材を含む層を形成し、この層を地下水が透過する際に、地下水に含まれるセシウムを吸着させることもできる。土壌処理では、セシウムを含む土壌に直接投入する所謂原位置浄化法に有用であり、土壌に投入する方法には特に制限は無く、(a)土壌を掘り起こし本発明のセシウム吸着材と混合した後埋め戻す、(b)スラリー状にした本発明のセシウム吸着材を土壌に注入する等、土壌の性状、地形等に応じて適宜選択できる。また、水処理、土壌処理のいずれにおいても、当該鉄酸化物が磁着性を有していると、セシウムを吸着させた後、分離する必要が生じれば、磁別することで容易に分離できる。 Moreover, this invention is an environmental treatment method, Comprising: The said cesium adsorbent is thrown into the environment containing cesium, and cesium is adsorb | sucked. In order to adsorb cesium contained in the environment of water or soil, a known method used in water treatment, soil treatment or the like can be used. For example, in the water treatment, the cesium adsorbing material of the present invention may be put into water containing cesium to adsorb and insolubilize cesium, and then filtered. Alternatively, the cesium adsorbent of the present invention can be packed in a treatment tower or supported on a filter. In the treatment of groundwater, for example, a layer containing the cesium adsorbent of the present invention is formed in the soil, and cesium contained in the groundwater can be adsorbed when the groundwater permeates through this layer. In soil treatment, it is useful for the so-called in-situ purification method, which is directly put into soil containing cesium, and there is no particular limitation on the method to put into soil, (a) after digging up the soil and mixing with the cesium adsorbent of the present invention It can be appropriately selected according to the properties of the soil, topography, etc., such as backfilling, or (b) injecting the slurry of the cesium adsorbent of the present invention into the soil. In both water treatment and soil treatment, if the iron oxide has magnetic adhesion, it is easily separated by magnetic separation if it is necessary to separate it after adsorbing cesium. it can.
本発明の環境処理方法は、セシウムの浄化能力に優れ、放射性セシウムの除染に有用である。従来のセシウム吸着材では、浄化対象となる放射性セシウム以外に、ナトリウム等の無機イオンが含まれる環境下では、浄化対象のセシウムの吸着能力が低下することが知られているが、本発明では、このような夾雑イオンの存在下でも、十分な吸着能力を有している。 The environmental treatment method of the present invention is excellent in cesium purification capacity and is useful for decontamination of radioactive cesium. In the conventional cesium adsorbent, it is known that, in an environment containing inorganic ions such as sodium other than radioactive cesium to be purified, the ability to adsorb cesium to be purified is reduced. Even in the presence of such contaminating ions, it has a sufficient adsorption capacity.
本発明の吸着材は、中性下では長期に渡って優れたセシウム吸着能を維持でき、一方、酸性下やアルカリ性下では、容易にセシウムを脱離させることができる。このため、放射性セシウムの除染に用いた吸着材を、濾別、磁別等の手段で、環境中から分離、回収し、水中に分散させ、分散液のｐＨを酸性又はアルカリ性に調整すれば、吸着材から放射性セシウムを除去できる。除去後の吸着材は再使用が可能となり、放射性セシウムが溶出した水を濃縮すれば、放射性廃棄物の量を大幅に低減できる。セシウムを脱離させるｐＨは、３．０以下又は１１．０以上が好ましい。 The adsorbent of the present invention can maintain an excellent cesium adsorbing ability for a long time under neutral conditions, and can easily desorb cesium under acidic and alkaline conditions. For this reason, if the adsorbent used for decontamination of radioactive cesium is separated and recovered from the environment by means of filtration, magnetic separation, etc., dispersed in water, and the pH of the dispersion is adjusted to be acidic or alkaline The radioactive cesium can be removed from the adsorbent. The adsorbent after removal can be reused, and the amount of radioactive waste can be greatly reduced if the water from which radioactive cesium is eluted is concentrated. The pH at which cesium is eliminated is preferably 3.0 or less or 11.0 or more.
以下に本発明の実施例を示すが、本発明はこれらに制限されるものではない。 Examples of the present invention are shown below, but the present invention is not limited thereto.
実施例１（様態（イ）：（ii）の方法）
純水２リットルに、硫酸第一鉄・７水和物１００ｇを添加し、撹拌、溶解して水溶液とした。その後、撹拌を継続して、液温を７０℃に昇温し、４８００ミリリットル／分の流速で水溶液中に空気を吹き込みながら、７．３重量％の濃度のケイ酸ナトリウム水溶液１１７０ミリリットルを添加して中和し、酸化率７５．４％まで酸化した。酸化後の溶液のｐＨは、６．０であった。得られた生成物を濾過、洗浄し、恒温乾燥機内で窒素注入しながら６０℃の温度で２４時間乾燥して、Ｆｅ／Ｓｉ比で１／２．１２のケイ素を含む、本発明のセシウム吸着材（試料Ａ）を得た。
Example 1 (Mode (I): Method (ii))
100 g of ferrous sulfate heptahydrate was added to 2 liters of pure water, stirred and dissolved to obtain an aqueous solution. Then, stirring was continued, the liquid temperature was raised to 70 ° C., and 1170 ml of an aqueous solution of sodium silicate having a concentration of 7.3% by weight was added while blowing air into the aqueous solution at a flow rate of 4800 ml / min. Neutralized and oxidized to an oxidation rate of 75.4%. The pH of the solution after oxidation was 6.0. The obtained product is filtered, washed, dried at a temperature of 60 ° C. for 24 hours while injecting nitrogen in a constant temperature dryer, and containing silicon having an Fe / Si ratio of 1 / 2.12. A material (sample A) was obtained.
実施例２（様態（イ）：（ii）の方法）
純水２リットルに、硫酸第一鉄・７水和物２０ｇを添加し、撹拌、溶解して水溶液とした。その後、撹拌を継続して、液温を７０℃に昇温し、４８００ミリリットル／分の流速で水溶液中に空気を吹き込みながら、水酸化アルミニウム５ｇを添加した後、１３．３重量％の濃度のケイ酸ナトリウム水溶液１３０ミリリットルを添加して中和し、酸化率９４．２％まで酸化した。酸化後の溶液のｐＨは、６．１であった。得られた生成物を、実施例１と同様に、濾過、洗浄、乾燥して、Ｆｅ／Ｓｉ／Ａｌ比で１／２．１４／０．８９のケイ素とアルミニウムを含む、本発明のセシウム吸着材（試料Ｂ）を得た。
Example 2 (Mode (I): Method (ii))
20 g of ferrous sulfate heptahydrate was added to 2 liters of pure water, stirred and dissolved to obtain an aqueous solution. Then, stirring was continued, the liquid temperature was raised to 70 ° C., 5 g of aluminum hydroxide was added while blowing air into the aqueous solution at a flow rate of 4800 ml / min, and then a concentration of 13.3% by weight was added. The solution was neutralized by adding 130 ml of an aqueous sodium silicate solution and oxidized to an oxidation rate of 94.2%. The pH of the solution after oxidation was 6.1. The obtained product was filtered, washed, and dried in the same manner as in Example 1 to contain cesium of the present invention containing silicon and aluminum with a Fe / Si / Al ratio of 1 / 2.14 / 0.89. A material (sample B) was obtained.
実施例３（様態（イ）：（ii）の方法）
実施例２において、硫酸第一鉄・７水和物の添加量を１００ｇ、水酸化アルミニウムの添加量を１０ｇ、ケイ酸ナトリウム水溶液の添加量を６７４ミリリットルとし、酸化率を６８．９％とした以外は、実施例２と同様にして、Ｆｅ／Ｓｉ／Ａｌ比で１／２．２２／０.３６のケイ素及びアルミニウムを含む、本発明のセシウム吸着材（試料Ｃ）を得た。尚、酸化後の溶液のｐＨは、６．０であった。
Example 3 (Mode (I): Method (ii))
In Example 2, the amount of ferrous sulfate heptahydrate added was 100 g, the amount of aluminum hydroxide added was 10 g, the amount of sodium silicate aqueous solution added was 674 ml, and the oxidation rate was 68.9%. Except for the above, a cesium adsorbent (sample C) of the present invention containing silicon and aluminum having a Fe / Si / Al ratio of 1 / 2.22 / 0.36 was obtained in the same manner as in Example 2. The pH of the solution after oxidation was 6.0.
実施例４（様態（イ）：（ii）の方法）
純水２リットルに、硫酸第一鉄・７水和物１００ｇを添加し、撹拌、溶解して水溶液とした。その後、撹拌を継続して、液温を７０℃に昇温し、４８００ミリリットル／分の流速で水溶液中に空気を吹き込みながら、水酸化アルミニウム５ｇ、水酸化マグネシウム５ｇを添加した後、１３．３重量％の濃度のケイ酸ナトリウム水溶液５４５ミリリットルを添加して中和し、酸化率７４．８％まで酸化した。酸化後の溶液のｐＨは、６．０であった。得られた生成物を、実施例１と同様に、濾過、洗浄、乾燥して、Ｆｅ／Ｓｉ／Ａｌ／Ｍｇ比で１／１.７９／０.１８／０.２４のケイ素、アルミニウム及びマグネシウムを含む、本発明のセシウム吸着材（試料Ｄ）を得た。
Example 4 (Mode (I): Method (ii))
100 g of ferrous sulfate heptahydrate was added to 2 liters of pure water, stirred and dissolved to obtain an aqueous solution. Then, stirring was continued, the liquid temperature was raised to 70 ° C., 5 g of aluminum hydroxide and 5 g of magnesium hydroxide were added while blowing air into the aqueous solution at a flow rate of 4800 ml / min, and then 13.3. The solution was neutralized by adding 545 ml of a sodium silicate aqueous solution having a concentration of% by weight and oxidized to an oxidation rate of 74.8%. The pH of the solution after oxidation was 6.0. The obtained product was filtered, washed and dried in the same manner as in Example 1 to obtain silicon / aluminum / magnesium with an Fe / Si / Al / Mg ratio of 1 / 1.79 / 0.18 / 0.24. The cesium adsorption material (sample D) of this invention containing this was obtained.
実施例５（様態（イ）：（ii）の方法）
実施例３において、空気の吹込みを、アルミニウム化合物、ケイ素化合物の添加後に行い、ケイ酸ナトリウム水溶液の添加量を４１０ミリリットルとし、酸化率を６０．０％とした以外は、実施例３と同様にして、Ｆｅ／Ｓｉ／Ａｌ比で１／１．３５／０．３６のケイ素及びアルミニウムを含む、本発明のセシウム吸着材（試料Ｅ）を得た。尚、酸化後の溶液のｐＨは、３．５であった。
Example 5 (Mode (I): Method (ii))
In Example 3, air was blown after the addition of the aluminum compound and silicon compound, the amount of sodium silicate aqueous solution added was 410 ml, and the oxidation rate was 60.0%. Thus, the cesium adsorbent of the present invention (sample E) containing silicon and aluminum having a Fe / Si / Al ratio of 1 / 1.35 / 0.36 was obtained. The pH of the solution after oxidation was 3.5.
実施例６（様態（ロ）：（iii）の方法）
純水２リットルに、硫酸第一鉄・７水和物１００ｇを添加し、撹拌、溶解して水溶液とした。その後、撹拌を継続して、液温を７０℃に昇温し、５重量％の濃度の水酸化ナトリウム水溶液を添加してｐＨ８．０に中和した。次いで、１３．３重量％の濃度のケイ酸ナトリウム水溶液１００ミリリットルを添加しながら、ｐＨが１０．０になった時点から４８００ミリリットル／分の流速で水溶液中に空気を吹き込んだ。ケイ酸ナトリウム水溶液を添加後に、９．８重量％の濃度の硫酸を添加し、最終的にｐＨ６．０に中和して、酸化率７３．６％まで酸化した。得られた生成物を、実施例１と同様に、濾過、洗浄、乾燥して、Ｆｅ／Ｓｉ比で１／０．３３のケイ素を含む、本発明のセシウム吸着材（試料Ｆ）を得た。
Example 6 (Mode (b): Method of (iii))
100 g of ferrous sulfate heptahydrate was added to 2 liters of pure water, stirred and dissolved to obtain an aqueous solution. Then, stirring was continued, the liquid temperature was raised to 70 ° C., and a 5 wt% sodium hydroxide aqueous solution was added to neutralize to pH 8.0. Next, while adding 100 ml of a sodium silicate aqueous solution having a concentration of 13.3% by weight, air was blown into the aqueous solution at a flow rate of 4800 ml / min from the time when the pH reached 10.0. After the addition of the aqueous sodium silicate solution, sulfuric acid having a concentration of 9.8% by weight was added, finally neutralized to pH 6.0, and oxidized to an oxidation rate of 73.6%. The obtained product was filtered, washed, and dried in the same manner as in Example 1 to obtain a cesium adsorbent (sample F) of the present invention containing silicon at a Fe / Si ratio of 1 / 0.33. .
実施例７（様態（ロ）：（iii）の方法）
純水２リットルに、硫酸第一鉄・７水和物１００ｇを添加し、撹拌、溶解して水溶液とした。その後、撹拌を継続して、液温を７０℃に昇温し、４８００ミリリットル／分の流速で水溶液中に空気を吹き込みながら、５重量％の濃度の水酸化ナトリウム水溶液を添加しｐＨ８．０に中和した。次いで、１３．３重量％の濃度のケイ酸ナトリウム水溶液７９ミリリットルを添加し、ｐＨを１０．０とした後、９．８重量％の濃度の硫酸でｐＨ６．０に中和して、酸化率６９．８％まで酸化した。得られた生成物を、実施例１と同様に、濾過、洗浄、乾燥して、Ｆｅ／Ｓｉ比で１／０．２６のケイ素を含む、本発明のセシウム吸着材（試料Ｇ）を得た。
Example 7 (Mode (b): Method of (iii))
100 g of ferrous sulfate heptahydrate was added to 2 liters of pure water, stirred and dissolved to obtain an aqueous solution. Then, stirring was continued, the liquid temperature was raised to 70 ° C., and 5% by weight sodium hydroxide aqueous solution was added to pH 8.0 while blowing air into the aqueous solution at a flow rate of 4800 ml / min. Neutralized. Subsequently, 79 ml of an aqueous solution of sodium silicate having a concentration of 13.3% by weight was added to adjust the pH to 10.0, and then neutralized to pH 6.0 with sulfuric acid having a concentration of 9.8% by weight to obtain an oxidation rate. Oxidized to 69.8%. The obtained product was filtered, washed and dried in the same manner as in Example 1 to obtain the cesium adsorbent of the present invention (sample G) containing silicon having a Fe / Si ratio of 1 / 0.26. .
実施例８（様態（ロ）：（iii）の方法）
実施例６において、硫酸第一鉄・７水和物の中和ｐＨを５．７とし、ケイ酸ナトリウムの添加量を５７３ミリリットル、酸化率を７３．９％とした以外は実施例６と同様にして、Ｆｅ／Ｓｉ比で１／１．８８のケイ素を含む、本発明のセシウム吸着材（試料Ｈ）を得た。
Example 8 (Mode (b): Method of (iii))
Example 6 was the same as Example 6 except that the neutralization pH of ferrous sulfate heptahydrate was 5.7, the amount of sodium silicate added was 573 ml, and the oxidation rate was 73.9%. Thus, the cesium adsorbent of the present invention (sample H) containing silicon with an Fe / Si ratio of 1 / 1.88 was obtained.
実施例９（様態（ロ）：（iii）の方法）
実施例７において、硫酸第一鉄・７水和物の中和ｐＨを５．７とし、ケイ酸ナトリウムの添加量を１９４ミリリットル、酸化率を８５．２％とした以外は実施例７と同様にして、Ｆｅ／Ｓｉ比で１／０．６４のケイ素を含む、本発明のセシウム吸着材（試料Ｉ）を得た。
Example 9 (mode (b): method of (iii))
Example 7 is the same as Example 7 except that the neutralization pH of ferrous sulfate heptahydrate was 5.7, the amount of sodium silicate added was 194 ml, and the oxidation rate was 85.2%. Thus, the cesium adsorbent of the present invention (sample I) containing silicon having an Fe / Si ratio of 1 / 0.64 was obtained.
実施例１０（様態（ロ）：（iii）の方法）
実施例６において、ケイ酸ナトリウムの添加量を１４５ミリリットルとし、鉄化合物と中和剤の添加後、ケイ素化合物の添加前に、水酸化アルミニウム０．５ｇを添加して、酸化率を７２．４％とした以外は実施例６と同様にして、Ｆｅ／Ｓｉ／Ａｌ比で１／０．４８／０．０２のケイ素及びアルミニウムを含む、本発明のセシウム吸着材（試料Ｊ）を得た。
Example 10 (Mode (b): Method of (iii))
In Example 6, the amount of sodium silicate added was 145 ml, 0.5 g of aluminum hydroxide was added after the addition of the iron compound and the neutralizing agent and before the addition of the silicon compound, and the oxidation rate was 72.4. The cesium adsorbent of the present invention (sample J) containing silicon and aluminum having a Fe / Si / Al ratio of 1 / 0.48 / 0.02 was obtained in the same manner as in Example 6 except that the content was%.
実施例１１（様態（ロ）：（iii）の方法）
実施例７において、ケイ酸ナトリウムの添加量を１１０ミリリットルとし、鉄化合物と中和剤の添加後、ケイ素化合物の添加前に、水酸化アルミニウム０．５ｇを添加して、酸化率を７１．１％とした以外は実施例６と同様にして、Ｆｅ／Ｓｉ／Ａｌ比で１／０．３６／０．０２のケイ素及びアルミニウムを含む、本発明のセシウム吸着材（試料Ｋ）を得た。
Example 11 (Mode (b): Method of (iii))
In Example 7, sodium silicate was added in an amount of 110 ml, 0.5 g of aluminum hydroxide was added after the addition of the iron compound and the neutralizing agent and before the addition of the silicon compound, and the oxidation rate was 71.1. The cesium adsorbent of the present invention (sample K) containing silicon and aluminum having a Fe / Si / Al ratio of 1 / 0.36 / 0.02 was obtained in the same manner as in Example 6 except that the content was%.
実施例１２（様態（イ）：（ii）の方法）
硫酸第一鉄を総Ｆｅ量として８．６７ｇ／リットル含む、硫酸法酸化チタンの製造工程から発生した副生硫酸２リットルを７０℃に昇温した。撹拌して、４８００ミリリットル／分の流速で副生硫酸中に空気を吹き込みながら、１３．３重量％の濃度のケイ酸ナトリウム水溶液７５０ミリリットルを添加して中和し、酸化率７５．７％まで酸化した。酸化後の溶液のｐＨは、６．０であった。得られた生成物を、実施例１と同様にして、濾過、洗浄し、乾燥して、Ｆｅ／Ｓｉ比で１／２．８６のケイ素を含む、本発明のセシウム吸着材（試料Ｌ）を得た。
Example 12 (Mode (I): Method (ii))
2 liters of by-product sulfuric acid generated from the production process of sulfuric acid method titanium oxide containing 8.67 g / liter of ferrous sulfate as a total Fe amount was heated to 70 ° C. While stirring and blowing air into the by-product sulfuric acid at a flow rate of 4800 ml / min, neutralize by adding 750 ml of an aqueous solution of sodium silicate having a concentration of 13.3% by weight to an oxidation rate of 75.7% Oxidized. The pH of the solution after oxidation was 6.0. The obtained product was filtered, washed and dried in the same manner as in Example 1, and the cesium adsorbent of the present invention (sample L) containing silicon having a Fe / Si ratio of 1 / 2.86 was obtained. Obtained.
実施例１３（様態（イ）：（ii）の方法）
実施例１２において、ケイ酸ナトリウムの添加量を６４２ミリリットルとし、ケイ素化合物の添加前に、水酸化アルミニウム１０ｇを添加して、酸化率を７０．６％とした以外は実施例１２と同様にして、Ｆｅ／Ｓｉ／Ａｌ比で１／２．４５／０．４１のケイ素及びアルミニウムを含む、本発明のセシウム吸着材（試料Ｍ）を得た。
Example 13 (Mode (I): Method (ii))
In Example 12, the amount of sodium silicate added was 642 ml, and before adding the silicon compound, 10 g of aluminum hydroxide was added to set the oxidation rate to 70.6%. A cesium adsorbent (sample M) of the present invention containing silicon and aluminum having a Fe / Si / Al ratio of 1 / 2.45 / 0.41 was obtained.
実施例１４（様態（ロ）：（iii）の方法）
硫酸第一鉄を総Ｆｅ量として８．６７ｇ／リットル含む、硫酸法酸化チタンの製造工程から発生した副生硫酸２リットルを７０℃に昇温した。撹拌して、４８００ミリリットル／分の流速で副生硫酸中に空気を吹き込みながら、５重量％の濃度の水酸化ナトリウム水溶液を２５０ミリリットル添加し、水酸化アルミニウム０．５ｇを添加し、更に１００ミリリットルのケイ酸ナトリウムを添加した。その後、５重量％の濃度の水酸化ナトリウム水溶液１８６ミリリットルを再度添加して、ｐＨを６．０に調整し、酸化率を８５．０％とした。得られた生成物を、実施例１と同様にして、濾過、洗浄し、乾燥して、Ｆｅ／Ｓｉ／Ａｌ比で１／０．３８／０．０２のケイ素及びアルミニウムを含む、本発明のセシウム吸着材（試料Ｎ）を得た。
Example 14 (Mode (b): Method of (iii))
2 liters of by-product sulfuric acid generated from the production process of sulfuric acid method titanium oxide containing 8.67 g / liter of ferrous sulfate as a total Fe amount was heated to 70 ° C. While stirring and blowing air into the by-product sulfuric acid at a flow rate of 4800 ml / min, 250 ml of 5 wt% sodium hydroxide aqueous solution was added, 0.5 g of aluminum hydroxide was added, and another 100 ml Of sodium silicate was added. Thereafter, 186 ml of a 5% by weight aqueous sodium hydroxide solution was added again to adjust the pH to 6.0 and the oxidation rate to 85.0%. The product obtained is filtered, washed and dried in the same manner as in Example 1 and contains silicon and aluminum at a Fe / Si / Al ratio of 1 / 0.38 / 0.02. A cesium adsorbent (sample N) was obtained.
実施例１５（様態（ハ）：（ii）の方法）
実施例１３において、先ず、市販のマグネタイト（Ｆｅ３Ｏ４）６．０ｇを添加し、次いで、水酸化アルミニウム０．５ｇを添加した後、６２６ミリリットルのケイ酸ナトリウムを添加して、酸化率を７１．５％とした以外は実施例１３同様にして、コア・シェル構造を有し、コア部がマグネタイトであり、シェル部がＦｅ／Ｓｉ／Ａｌ比で１／２．３９／０．０２のケイ素及びアルミニウムを含む、本発明のセシウム吸着材（試料Ｏ）を得た。
Example 15 (Mode (c): Method (ii))
In Example 13, first, 6.0 g of commercially available magnetite (Fe 3 O 4 ) was added, then 0.5 g of aluminum hydroxide was added, and then 626 ml of sodium silicate was added to reduce the oxidation rate. The core / shell structure was obtained in the same manner as in Example 13 except that the content was 71.5%, the core was magnetite, and the shell was 1 / 2.39 / 0.02 in Fe / Si / Al ratio. A cesium adsorbent of the present invention (sample O) containing silicon and aluminum was obtained.
実施例１６（様態（イ）：（ii）の方法）
硫酸第一鉄を総Ｆｅ量として７．６５ｇ／リットル含む、硫酸法酸化チタンの製造工程から発生した副生硫酸２リットルを７０℃に昇温した。撹拌して、４８００ミリリットル／分の流速で副生硫酸中に空気を吹き込みながら、１３．３重量％の濃度のケイ酸ナトリウム水溶液９２０ミリリットルを添加して中和し、酸化率６４．５％まで酸化した。酸化後の溶液のｐＨは、６．０１であった。得られた生成物を、実施例１と同様にして、濾過、洗浄し、乾燥して、Ｆｅ／Ｓｉ比で１／３．９７のケイ素を含む、本発明のセシウム吸着材（試料Ｐ）を得た。
Example 16 (Mode (I): Method (ii))
2 liters of by-product sulfuric acid generated from the production process of sulfuric acid method titanium oxide containing ferrous sulfate as a total Fe amount of 7.65 g / liter was heated to 70 ° C. While stirring, air is blown into the by-product sulfuric acid at a flow rate of 4800 ml / min, and neutralized by adding 920 ml of a sodium silicate aqueous solution having a concentration of 13.3% by weight to an oxidation rate of 64.5% Oxidized. The pH of the solution after oxidation was 6.01. The obtained product was filtered, washed, and dried in the same manner as in Example 1 to obtain the cesium adsorbent (sample P) of the present invention containing silicon having a Fe / Si ratio of 1 / 3.97. Obtained.
実施例１７（様態（イ）：（ii）の方法）
実施例１６において、ケイ酸ナトリウムの添加量を１１００ミリリットルとし、ケイ素化合物の添加前に、Ａｌ２Ｏ３として８．１重量％濃度の硫酸アルミニウム水溶液１００ミリリットルを添加して、酸化率を６５．４％とした以外は実施例１６と同様にして、Ｆｅ／Ｓｉ／Ａｌ比で１／４．７５／０．７６のケイ素及びアルミニウムを含む、本発明のセシウム吸着材（試料Ｑ）を得た。
Example 17 (Mode (I): Method (ii))
In Example 16, the amount of sodium silicate added was 1100 ml, and before addition of the silicon compound, 100 ml of an 8.1 wt% aqueous aluminum sulfate solution as Al 2 O 3 was added to give an oxidation rate of 65. A cesium adsorbent of the present invention (sample Q) containing silicon and aluminum having a Fe / Si / Al ratio of 1 / 4.75 / 0.76 was obtained in the same manner as in Example 16 except that the content was 4%. .
実施例１８（様態（イ）：（ii）の方法）
実施例１７において、ケイ酸ナトリウム水溶液の添加量を８９０ミリリットル硫酸アルミニウム溶液の添加量を５０ミリリットルとし、酸化率を６５．４％とした以外は、実施例１７と同様にして、Ｆｅ／Ｓｉ／Ａｌ比で１／３．８４／０．３８のケイ素及びアルミニウムを含む、本発明のセシウム吸着材（試料Ｒ）を得た。
Example 18 (Mode (I): Method (ii))
In Example 17, the Fe / Si / Fe / Si / Fe solution was added in the same manner as in Example 17 except that the addition amount of the sodium silicate aqueous solution was 890 ml, the addition amount of the aluminum sulfate solution was 50 ml and the oxidation rate was 65.4%. A cesium adsorbent of the present invention (sample R) containing silicon and aluminum with an Al ratio of 1 / 3.84 / 0.38 was obtained.
比較例１
市販のγ−Ｆｅ２Ｏ３を、比較対象のセシウム吸着材（試料Ｓ）とした。
Comparative Example 1
Commercially available γ-Fe 2 O 3 was used as a cesium adsorbent for comparison (sample S).
比較例２
市販のレピドクロサイト鉄酸化物（ＦｅＯＯＨ）を、比較対象のセシウム吸着材（試料Ｔ）とした。
Comparative Example 2
Commercially available lipidocrosite iron oxide (FeOOH) was used as a cesium adsorbent for comparison (sample T).
比較例３
Ｆｅとして６．７ｇ／リットルの濃度の硫酸第一鉄・７水和物水溶液７リットルを４５℃に昇温した。撹拌して、４８００ミリリットル／分の流速で溶液中に空気を吹き込みながら、ｐＨが８．５となるように５重量％の濃度の水酸化ナトリウム水溶液を添加して中和し、酸化率１００％まで酸化した後、得られた生成物を、実施例１と同様にして、濾過、洗浄し、乾燥して、比較対象のセシウム吸着材（試料Ｕ）とした。
Comparative Example 3
7 liters of ferrous sulfate heptahydrate aqueous solution having a concentration of 6.7 g / liter as Fe was heated to 45 ° C. While stirring, air was blown into the solution at a flow rate of 4800 ml / min, and neutralized by adding a 5% by weight sodium hydroxide aqueous solution so that the pH was 8.5, and the oxidation rate was 100%. Then, the obtained product was filtered, washed and dried in the same manner as in Example 1 to obtain a comparative cesium adsorbent (sample U).
実施例１〜１８で得られた試料Ａ〜Ｒの内容を、表１に取り纏めた。 The contents of Samples A to R obtained in Examples 1 to 18 are summarized in Table 1.
評価１
実施例１〜１８、比較例１〜３の試料Ａ〜Ｕ各２ｇを、塩化セシウムを溶解してセシウム濃度を１０ｍｇ／リットルとした試験液２００ミリリットルに加えた。２４時間振盪後、遠心分離機を用い、回転数３０００ｒｐｍで２０分間かけて遠心分離した。遠心分離した上澄み液（１）を０．４５μｍのフィルターでろ過してから、セシウムの濃度を、発光分析装置（Ｔｈｅｒｍｏ Ｆｉｓｈｅｒ Ｓｃｈｉｅｎｔｉｆｉｃ社製：ｉＣＡＰ Ｑ ＩＣＰ−ＭＳ）により測定した。
Evaluation 1
2 g of each of samples A to U of Examples 1 to 18 and Comparative Examples 1 to 3 was added to 200 ml of a test solution in which cesium chloride was dissolved to give a cesium concentration of 10 mg / liter. After shaking for 24 hours, the mixture was centrifuged at 3000 rpm for 20 minutes using a centrifuge. After the centrifuged supernatant (1) was filtered through a 0.45 μm filter, the concentration of cesium was measured with an emission analyzer (manufactured by Thermo Fisher Scientific: iCAP Q ICP-MS).
評価２
実施例６〜１１（試料Ｆ〜Ｋ）について、評価１を行った後の試料０．５ｇに純水５０ミリリットルを添加し、評価１と同様にして、再度遠心分離し、上澄み液（２）中のセシウムの濃度を測定した。
Evaluation 2
For Examples 6 to 11 (Samples F to K), 50 ml of pure water was added to 0.5 g of the sample after performing Evaluation 1, and centrifuged again in the same manner as in Evaluation 1 to obtain a supernatant (2) The concentration of cesium in it was measured.
結果を表２に示す。
本発明のセシウム吸着材は、優れたセシウムの吸着能力を有しており、また、一旦、吸着したセシウムは脱離し難く、セシウムが高度に不溶化されていることが判る。
The results are shown in Table 2.
It can be seen that the cesium adsorbent of the present invention has an excellent ability to adsorb cesium, and once adsorbed cesium is difficult to desorb and cesium is highly insolubilized.
評価３
実施例３、６、１２〜１５の試料Ｃ、Ｆ、Ｌ〜Ｏ各２ｇを、塩化セシウムを溶解してセシウム濃度を下記表３記載の濃度とし、更にナトリウム濃度が１重量％となるように塩化ナトリウムを添加した試験液２００ミリリットルに加えた。評価１と同様にして、セシウムの除去率を算出した。
Evaluation 3
Samples C, F, and L to O of Examples 3, 6, and 12 to 15 were dissolved in cesium chloride so that the cesium concentration was as shown in Table 3 below, and the sodium concentration was 1% by weight. The test solution was added to 200 ml of sodium chloride. In the same manner as in Evaluation 1, the removal rate of cesium was calculated.
結果を表３に示す。
本発明のセシウム吸着材は、夾雑イオンの存在下でも、十分なセシウムの吸着能力を有していることが判る。
The results are shown in Table 3.
It can be seen that the cesium adsorbent of the present invention has sufficient cesium adsorption ability even in the presence of impurity ions.
評価４
実施例１２〜１５の試料Ｌ〜Ｏについて、各１０ｇを、塩化セシウムを溶解してセシウム濃度を１ｍｇ／リットルとした試験液１リットルに加えた。評価１と同様にして、セシウム吸着試験を行った。この吸着試験後の試料に純水を加え試験溶液とし、ｐＨをシュウ酸・シュウ酸アンモニウム（シュウ酸とシュウ酸アンモニウム）、水酸化ナトリウムを用いて、それぞれ３．０、１２．５に調整した。その後、評価２と同様にして、セシウムの溶出率を算出した。
Evaluation 4
For Samples L to O of Examples 12 to 15, 10 g of each was added to 1 liter of a test solution in which cesium chloride was dissolved to give a cesium concentration of 1 mg / liter. A cesium adsorption test was conducted in the same manner as in Evaluation 1. Pure water was added to the sample after this adsorption test to obtain a test solution, and the pH was adjusted to 3.0 and 12.5 using oxalic acid / ammonium oxalate (oxalic acid and ammonium oxalate) and sodium hydroxide, respectively. . Thereafter, the elution rate of cesium was calculated in the same manner as in Evaluation 2.
結果を表４に示す。
本発明のセシウム吸着材は、水中でｐＨを酸性又はアルカリ性に調整することにより、セシウムが容易に脱離することが判る。
The results are shown in Table 4.
It can be seen that the cesium adsorbent of the present invention easily desorbs cesium by adjusting the pH to be acidic or alkaline in water.
本発明の吸着材は、放射性セシウムで汚染された水、土壌等の除染に有用である。 The adsorbent of the present invention is useful for decontamination of water, soil and the like contaminated with radioactive cesium.
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