JP2016020884A - Decontamination method for soil contaminated with radioactive substance - Google Patents

Decontamination method for soil contaminated with radioactive substance Download PDF

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JP2016020884A
JP2016020884A JP2014172150A JP2014172150A JP2016020884A JP 2016020884 A JP2016020884 A JP 2016020884A JP 2014172150 A JP2014172150 A JP 2014172150A JP 2014172150 A JP2014172150 A JP 2014172150A JP 2016020884 A JP2016020884 A JP 2016020884A
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JP5946044B2 (en
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アイ バン トラン
Ban Toran Ai
バン トラン アイ
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Corelex Sanei Co Ltd
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PROBLEM TO BE SOLVED: To provide a decontamination method for soil contaminated with a radioactive substance, with improved efficiency of decontaminating radioactive cesium 134 and radioactive cesium 137.SOLUTION: At least one of a chloride, a sulfate, and an iron cyanide selected from a group consisting of a potassium chloride, a potassium sulfate, a magnesium sulfate, a copper sulfate, and a potassium ferrocyanide that includes both of potassium and iron are dissolved in water to be immersed in a porous particle carbonated burned product that is formed from paper sludge, and is mixed with soil contaminated with a radioactive substance so as to cause an ion-exchange with radioactive cesium 134 and radioactive cesium 137.SELECTED DRAWING: None

Description

本発明は、放射性物質によって汚染された農地、民間居住地域、公共施設等の土壌を除染する放射性物質汚染土壌の除染方法に関するものであり、特に、ペーパースラッジからなる多孔質粒状炭化焼成物によって放射性セシウム134及び137の除染効率を向上させる方法に関するものである。   The present invention relates to a method for decontaminating radioactive material-contaminated soil that decontaminates soil such as agricultural land, private residential areas, and public facilities contaminated with radioactive material, and in particular, porous granular carbonized fired material comprising paper sludge. Relates to a method for improving the decontamination efficiency of radioactive cesium 134 and 137.

放射性物質汚染土壌の放射性セシウム134及び137を除染する方法として下記特許文献1には、塩化第一鉄、塩化第二鉄、硫酸第一鉄、硫酸第二鉄、硝酸第一鉄、硝酸第二鉄及びポリ硫酸鉄から選ばれる鉄塩、並びにアンモニウム塩、カリウム塩から選ばれる薬剤水溶液又は水で洗浄し、前記放射性物質汚染土壌の放射性セシウムを抽出して浄化を行い、薬剤水溶液又は水に、塩化セシウム、グリセリン又はエチレングリコールモノエチルエーテル(EGME=セロソルブ)を添加する方法が開示されている。しかし、放射性セシウム汚染薬剤水溶液、水、アルコール、有機溶媒セロソルブの処理方法、安心且つ安全に保管、貯蔵する方法には触れられていない。   As a method for decontaminating radioactive cesiums 134 and 137 in soil contaminated with radioactive substances, the following Patent Document 1 includes ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, ferrous nitrate, and ferrous nitrate. Wash with an iron salt selected from ferric iron and polysulfate, and a chemical aqueous solution or water selected from ammonium salt and potassium salt, extract and purify the radioactive cesium in the radioactive material-contaminated soil, , Cesium chloride, glycerin or ethylene glycol monoethyl ether (EGME = cellosolve) is disclosed. However, there is no mention of a method for treating radioactive cesium-contaminated chemical aqueous solution, water, alcohol, organic solvent cellosolve, and a safe and safe storage and storage method.

一方、下記特許文献2に記載された放射性物質汚染土壌の放射性セシウム134及び137の除染方法は、無機酸、有機酸等にてpH3になるように調整して加熱処理した後アルカリで中和し、更に陽イオンを生じる硫酸アンモニウムを含む洗浄水にて洗浄工程でイオン交換を行い、上清と沈殿土壌を分画するものである。この沈殿土壌は放射性セシウムが10Bq/kgであるため、放射性物質汚染土壌が除染されている。発生した上清は、モルデナイト、ゼオライト等の吸着剤で放射性物を吸着させた後、排水として系外に流出する。一方、放射性物質汚染吸着剤は遮蔽隔離する。これは、pH3の有機酸、陽イオンを生じる硫酸アンモニウムを含む洗浄水等の使用を原理原則とする除染方法であるが、最終工程の汚染吸着剤の遮蔽隔離方法には触れられていない。   On the other hand, the method for decontaminating radioactive cesium 134 and 137 in radioactive material contaminated soil described in Patent Document 2 below is adjusted to pH 3 with an inorganic acid, an organic acid or the like and then heat-treated, and then neutralized with an alkali. Further, ion exchange is performed in a washing step with washing water containing ammonium sulfate that generates cations, and the supernatant and precipitated soil are fractionated. Since this sedimentary soil has a radioactive cesium of 10 Bq / kg, the radioactive material contaminated soil is decontaminated. The generated supernatant adsorbs radioactive substances with an adsorbent such as mordenite and zeolite, and then flows out of the system as waste water. On the other hand, radioactive material-contaminated adsorbents are shielded and isolated. This is a decontamination method based on the principle of using a pH 3 organic acid, washing water containing ammonium sulfate that generates cations, etc., but does not touch on the final method of shielding and isolating the contaminant adsorbent.

本発明者は、ペーパースラッジからなる多孔質粒状炭化焼成物を用い、放射性物質汚染土壌の改良浄化テストを行い、放射性セシウム134及び137を放射性物質汚染土壌から除去可能であることを確認し、かつ、得られた白米の放射性物セシウム134及び137の合計の値である30Bq/kgが、日本基準値100Bq/kgより低い結果であることを、下記特許文献3に開示した。   The present inventor conducted an improved purification test of radioactive material-contaminated soil using a porous granular carbonized product made of paper sludge, confirmed that radioactive cesium 134 and 137 can be removed from the radioactive material-contaminated soil, and The following patent document 3 discloses that 30 Bq / kg, which is the total value of the obtained white rice radioactive materials cesium 134 and 137, is lower than the Japanese standard value of 100 Bq / kg.

ここで、ペーパースラッジからなる多孔質粒状炭化焼成物は、古紙、木材チップの単独、あるいは古紙や木材チップの両方を使用する製紙工場のペーパースラッジを炭化焼成することからなり、以下の構成である。   Here, the porous granular carbonized fired product made of paper sludge consists of carbonized and fired paper sludge of a paper mill that uses waste paper, wood chips alone, or both waste paper and wood chips, and has the following configuration. .

(1)pH8以上、望ましくは10以上、アルカリ相当値1.0〜4.0meq/g(NaOH)、望ましくは1.5〜2.5meq/g(NaOH)、カチオン交換容量1.0〜4.0meq/100g(NH4 +)、望ましくは1.5〜3.0meq/100g(NH4 +)、電気伝導度70〜150μS/cm、Na含有率:0.0003%以上、K含有率:0.0003%以上、有機分が25%未満、無機分が75%以上である多孔質粒状ペーパースラッジ炭化焼成物を、古紙、木材チップの単独あるいは古紙や木材チップの両方を使用する製紙工場からのペーパースラッジを炭化焼成することで生成し、前記多孔質粒状ペーパースラッジ炭化焼成物を放射性物質汚染土壌に散布や混合し、ヨウ素を含浸し、またはセシウムとのイオン交換を行うことで、放射性物質を前記放射性物質汚染土壌から除去する放射性物質汚染土壌の改良浄化方法。
(2)前記多孔質粒状ペーパースラッジ炭化焼成物の製造工程には、KIの溶液への含浸工程が含まれない場合、TEDAの溶液への含浸工程が含まれない場合、KIとTEDAとの混合物の溶液への含浸工程も含まれない場合、のいずれであってもよい。
(3)前記放射性物質汚染土壌は、放射性セシウム134及びセシウム137の合計濃度が800Bq/kg以上を含有する。
(4)前記放射性物質汚染土壌に拡散又は混合する前記多孔質粒状ペーパースラッジ炭化焼成物の添加量は、0.1〜6kg/m2(0.5〜50kg/m3)(乾土の0.1〜6重量%)、望ましくは1.0〜3.5kg/m2(8〜30kg/m3)(乾土の0.9〜3.3重量%)である。
(5)前記ペーパースラッジは、水分量50〜85%を有し、このペーパースラッジを造粒し、乾燥した後、乾留温度500〜1,300℃、望ましくは700〜1,200℃の還元炭化焼成炉で炭化焼成する。さらに望ましくは、800〜1,100℃で炭化焼成する。
(6)前記多孔質粒状ペーパースラッジ炭化焼成物は、絶乾重量で、可燃分(炭素を含む):15〜25%、TiO2:0.5〜3.0%、Na2O:0.0001〜0.0005%、K2O:0.0001〜0.0005%、SiO2:15〜35%、Al23:8〜20%、Fe23:5〜15%、CaO:15〜30%、MgO:1〜8%、その他(不純物):0.5〜3.0%を含み、これらの合計が100%であり、JIS C2141による吸水率が100〜160%、BET吸着法による比表面積が80〜150m2/gであり、連続気泡を有する。
(7)前記多孔質粒状ペーパースラッジ炭化焼成物は、容積空隙率が70%以上、空隙容積が1,000mm3/g以上を有し、平均空隙半径が20〜60μmであり、全空隙容積に占める半径1μm以上の空隙が70%以上、長径が1〜10mmの球状、楕円状、円柱状等である混合物質であり、黒色である。
(1) pH 8 or more, desirably 10 or more, alkali equivalent value 1.0 to 4.0 meq / g (NaOH), desirably 1.5 to 2.5 meq / g (NaOH), cation exchange capacity 1.0 to 4 0.0 meq / 100 g (NH 4 + ), desirably 1.5 to 3.0 meq / 100 g (NH 4 + ), electric conductivity 70 to 150 μS / cm, Na content: 0.0003% or more, K content: A porous granular paper sludge carbonized fired product with 0.0003% or more, organic content less than 25%, and inorganic content of 75% or more from a paper mill using waste paper, wood chips alone or both waste paper and wood chips. Carbon sludge produced by carbonizing and firing the porous granular paper sludge carbonized product, sprayed and mixed with radioactive material contaminated soil, impregnated with iodine, or ions with cesium By performing the conversion, improved method of purifying radioactive contaminated soil to remove radioactive material from the radioactive substance contaminated soil.
(2) When the manufacturing process of the carbonized calcined product of the porous granular paper sludge does not include the step of impregnating the KI solution, when the step of impregnating the TEDA solution is not included, the mixture of KI and TEDA In the case where the impregnation step into the solution is not included, any of them may be used.
(3) The radioactive substance-contaminated soil contains a total concentration of radioactive cesium 134 and cesium 137 of 800 Bq / kg or more.
(4) The amount of the porous granular paper sludge carbonized product to be diffused or mixed in the radioactive material-contaminated soil is 0.1-6 kg / m 2 (0.5-50 kg / m 3 ) (0 of dry soil 0.1 to 6% by weight), desirably 1.0 to 3.5 kg / m 2 (8 to 30 kg / m 3 ) (0.9 to 3.3% by weight of dry soil).
(5) The paper sludge has a moisture content of 50 to 85%, and after granulating and drying the paper sludge, the carbonization temperature is 500 to 1,300 ° C, preferably 700 to 1,200 ° C. Carbonized and fired in a firing furnace. More desirably, the carbonization is performed at 800 to 1,100 ° C.
(6) The carbonized calcined product of the porous granular paper sludge has an absolute dry weight, combustible content (including carbon): 15 to 25%, TiO 2 : 0.5 to 3.0%, Na 2 O: 0.00. 0001~0.0005%, K 2 O: 0.0001~0.0005 %, SiO 2: 15~35%, Al 2 O 3: 8~20%, Fe 2 O 3: 5~15%, CaO: 15-30%, MgO: 1-8%, other (impurities): 0.5-3.0%, the total of these is 100%, the water absorption rate according to JIS C2141 is 100-160%, BET adsorption The specific surface area according to the method is 80 to 150 m 2 / g and has open cells.
(7) The porous granular paper sludge carbonized product has a volume porosity of 70% or more, a void volume of 1,000 mm 3 / g or more, an average void radius of 20 to 60 μm, and a total void volume of It is a mixed material having a spherical shape, an elliptical shape, a cylindrical shape or the like in which a void having a radius of 1 μm or more occupies 70% or more and a major axis is 1 to 10 mm, and is black.

特開2012−237658号公報JP 2012-237658 A 特開2013−178132号公報JP 2013-178132 A 特開2013−068459号公報JP2013-0668459A

上記ペーパースラッジからなる多孔質粒状炭化焼成物(ペーパースラッジカーボン(以下「PSC」と記す。))は、放射性物質汚染土壌から放射性セシウム134及び137を除染することを確認したため、放射性物質のPSCへの影響予備テストを行った。その結果、PSCのカルシウム、鉄、マグネシウム、銅、カリウム、バリウム、塩素、硫黄等が減少したため、放射性物質汚染土壌の放射性セシウム134及び137が、PSCのカルシウム、鉄、マグネシウム、銅、カリウム、バリウムとのイオン交換を行ったと推定される。一般に、塩素、硫黄は単独で存在せず、前記の金属と結合し、金属塩の化合物が生成される。   Since it was confirmed that the porous granular carbonized product (paper sludge carbon (hereinafter referred to as “PSC”)) made of the above paper sludge decontaminates radioactive cesium 134 and 137 from radioactive material contaminated soil, A preliminary test was conducted. As a result, the PSC calcium, iron, magnesium, copper, potassium, barium, chlorine, sulfur, etc. decreased, so the radioactive cesium 134 and 137 of the radioactive material contaminated soil became PSC calcium, iron, magnesium, copper, potassium, barium. It is presumed that ion exchange with was performed. In general, chlorine and sulfur are not present alone, and are combined with the above metal to form a metal salt compound.

一方で、鉄−シアン化合物であるフェロシアン化コバルトあるいはフェロシアン化ニッケルは、放射性セシウムの選択吸着性が優れているが、形状が微粒子状であるため取り扱いが難しい。前記のPSCのカリウム、鉄等は放射性セシウムとのイオン交換を行うと推定するため、ヘキサシアノ鉄(II)酸カリウム三水和物(フェロシアン化カリウム)をPSCに含浸し、このカリウム及び鉄を共に含んだ鉄−シアン化合物の除染効率を調査し、カリウム、鉄等の放射性セシウムとのイオン交換性を再確認する。   On the other hand, cobalt ferrocyanide or nickel ferrocyanide, which is an iron-cyanide compound, is excellent in selective adsorption of radioactive cesium, but is difficult to handle because of its fine particle shape. In order to presume that potassium, iron, etc. of the PSC perform ion exchange with radioactive cesium, PSC is impregnated with potassium hexacyanoferrate (II) trihydrate (potassium ferrocyanide), and both the potassium and iron are contained. Investigate the decontamination efficiency of iron-cyanide compounds and reconfirm ion exchange properties with radioactive cesium such as potassium and iron.

本発明は、放射性セシウム134及び137と、金属塩化合物とのイオン交換反応を基にPSCを改良し、放射性物質汚染土壌の放射性セシウム134及び137の除染効率をより高める方法を提供するものである。   The present invention provides a method for improving the PSC based on the ion exchange reaction between radioactive cesium 134 and 137 and a metal salt compound, and further increasing the decontamination efficiency of radioactive cesium 134 and 137 in radioactive material contaminated soil. is there.

上記した課題を解決するために、本発明に係る放射性物質汚染土壌の除染方法は、イオン交換可能な金属の塩化物、硫酸塩、及び鉄‐シアン化合物からなる群から選択される1または2以上の化合物を、ペーパースラッジからなる多孔質粒状炭化焼成物に含浸させ、この多孔質粒状炭化焼成物と放射性物質汚染土壌とを混合し、前記放射性物質汚染土壌の放射性セシウム134及び137とのイオン交換を行う、ことを特徴とする。   In order to solve the above-described problem, the method for decontaminating radioactive material-contaminated soil according to the present invention is 1 or 2 selected from the group consisting of ion-exchangeable metal chlorides, sulfates, and iron-cyanide compounds. The above-mentioned compound is impregnated into a porous granular carbonized fired product made of paper sludge, this porous granular carbonized fired product and radioactive material contaminated soil are mixed, and ions of radioactive cesium 134 and 137 of the radioactive material contaminated soil are mixed. It is characterized by exchanging.

本発明に係る放射性物質汚染土壌の除染方法は、前記多孔質粒状炭化焼成物に含浸させる塩化物が塩化カリウムであり、この塩化カリウムが、前記多孔質粒状炭化焼成物の重量の0.5%以上5%以下である、ことを特徴とする。   In the method for decontaminating radioactive material-contaminated soil according to the present invention, the chloride impregnated in the porous granular carbonized fired product is potassium chloride, and the potassium chloride is 0.5% of the weight of the porous granular carbonized fired product. % Or more and 5% or less.

本発明に係る放射性物質汚染土壌の除染方法は、前記多孔質粒状炭化焼成物に含浸させる硫酸塩が、硫酸カリウム、硫酸マグネシウム、及び硫酸銅からなる群から選択される1または2以上の硫酸塩であり、前記硫酸カリウムが前記多孔質粒状炭化焼成物の重量の1%以上5%以下、前記硫酸マグネシウムが前記多孔質粒状炭化焼成物の重量の1%以上5%以下、及び前記硫酸銅が前記多孔質粒状炭化焼成物の重量の1%である、ことを特徴とする。   In the method for decontaminating radioactive material-contaminated soil according to the present invention, the sulfate impregnated in the porous granular carbonized product is one or more sulfuric acids selected from the group consisting of potassium sulfate, magnesium sulfate, and copper sulfate. A salt, wherein the potassium sulfate is 1% to 5% of the weight of the porous granular carbonized fired product, the magnesium sulfate is 1% to 5% of the weight of the porous granular carbonized fired product, and the copper sulfate Is 1% of the weight of the porous granular carbonized fired product.

本発明に係る放射性物質汚染土壌の除染方法は、前記多孔質粒状炭化焼成物に含浸させる鉄‐シアン化合物がフェロシアン化カリウムであり、このフェロシアン化カリウムが、前記多孔質粒状炭化焼成物の重量の0.5%以上5%以下である、ことを特徴とする。   In the method for decontaminating radioactive material-contaminated soil according to the present invention, the iron-cyanide compound impregnated in the porous granular carbonized fired product is potassium ferrocyanide, and this potassium ferrocyanide is 0% by weight of the porous granular carbonized fired product. It is characterized by being 5% or more and 5% or less.

本発明に係る放射性物質汚染土壌の除染方法は、塩化カリウムが、ペーパースラッジからなる多孔質粒状炭化焼成物の重量の0.5%以上5%以下であり、硫酸カリウムが、前記多孔質粒状炭化焼成物の重量の1%以上5%以下であり、硫酸マグネシウムが、前記多孔質粒状炭化焼成物の重量の1%以上5%以下であり、硫酸銅が、前記多孔質粒状炭化焼成物の重量の1%であり、前記塩化カリウム、前記硫酸カリウム、前記硫酸マグネシウム、及び前記硫酸銅からなる群から選択される1または2以上の化合物を、前記多孔質粒状炭化焼成物に含浸させ、この多孔質粒状炭化焼成物と放射性物質汚染土壌とを混合し、前記放射性物質汚染土壌の放射性セシウム134及び137とのイオン交換を行う、ことを特徴とする。   In the method for decontaminating radioactive material-contaminated soil according to the present invention, potassium chloride is 0.5% or more and 5% or less of the weight of the porous granular carbonized product made of paper sludge, and potassium sulfate is the porous granular form. 1% or more and 5% or less of the weight of the carbonized fired product, magnesium sulfate is 1% or more and 5% or less of the weight of the porous granular carbonized product, and copper sulfate is the porous granular carbonized product. 1% by weight of the porous granular carbonized fired product is impregnated with one or two or more compounds selected from the group consisting of the potassium chloride, the potassium sulfate, the magnesium sulfate, and the copper sulfate, A porous granular carbonized fired product and radioactive material-contaminated soil are mixed, and ion exchange with radioactive cesium 134 and 137 of the radioactive material-contaminated soil is performed.

本発明に係る放射性物質汚染土壌の除染方法は、コスト、実用性を総合的に満たし、放射性セシウム134及び137の除染効率を向上することができ、生産される米、野菜等の農産物の放射性セシウム134及び137を、簡単に日本基準値より低値にすることが可能である。   The method for decontamination of radioactive material-contaminated soil according to the present invention can comprehensively satisfy the cost and practicality, improve the decontamination efficiency of radioactive cesium 134 and 137, and produce agricultural products such as rice and vegetables to be produced. The radioactive cesium 134 and 137 can be easily made lower than the Japanese standard value.

本発明に係る放射性物質汚染土壌の除染方法によれば、放射性セシウム134及び137の除染効率を向上させて処理された放射性物質汚染土壌の空間ガンマ線量を、原子力発電所事故の場所から直線距離で320km以上離れている箇所と同等の値にすることが可能であり、環境と健康に対して安心、安全という利点がある。   According to the method for decontaminating radioactive material-contaminated soil according to the present invention, the spatial gamma dose of the radioactive material-contaminated soil treated by improving the decontamination efficiency of radioactive cesium 134 and 137 is linearly determined from the location of the nuclear power plant accident. It is possible to make it a value equivalent to a place separated by 320 km or more in distance, and there is an advantage of safety and security with respect to the environment and health.

本発明の実施形態に係る放射性物質汚染土壌の除染方法による放射性物質汚染土壌の経時変化がグラフで示された図である。It is the figure by which the time-dependent change of the radioactive material contamination soil by the decontamination method of the radioactive material contamination soil which concerns on embodiment of this invention was shown with the graph.

以下に、本発明の実施形態に係る放射性物質汚染土壌の除染方法を説明する。なお、本発明は以下に限定されるものではない。   Below, the decontamination method of the radioactive substance contamination soil which concerns on embodiment of this invention is demonstrated. The present invention is not limited to the following.

本発明の実施形態に係る放射性物質汚染土壌の除染方法は、イオン交換可能な金属の塩化物、硫酸塩、及び鉄‐シアン化合物からなる群から選択される1または2以上の化合物をPSCに含浸させ、これらのPSCと放射性物質汚染土壌とを混合することにより、放射性物質汚染土壌の放射性セシウム134及び137とのイオン交換を行うものである。   In the method for decontaminating radioactive material-contaminated soil according to an embodiment of the present invention, one or more compounds selected from the group consisting of ion-exchangeable metal chlorides, sulfates, and iron-cyanide compounds are converted into PSC. By impregnating and mixing these PSC and radioactive material-contaminated soil, ion exchange with radioactive cesium 134 and 137 of the radioactive material-contaminated soil is performed.

PSCと放射性物質汚染土壌との混合時において、放射性物質汚染土壌に含まれる放射性セシウム134及び137等の放射性物質のPSCへの影響を、ラボテストにて調査した。この試験では、2012年夏に福島県飯舘村で採取した放射性物質汚染土壌(100g絶乾(OD:oven dried)重量)をポリエチレン袋に入れ、メシュ袋に入れたPSC(10g、OD)を放射性物質汚染土壌に埋設し、25oCで10日間放置した。一方、ブランク試験では、同放射性物質汚染土壌(100g、OD)とPSC(10g、OD)とをポリエチレン袋に入れてよく混ぜた後、同じ条件下で試験を行った。放射性物質汚染土壌、PSCの各々の放射性セシウム134及び137、pH、イオン交換容量(CEC:cation exchange capacity)、汚染前後のPSCの金属組成を測定した。放射性物質汚染土壌及びPSCの品質結果を表1および図1に示し、汚染前後のPSCの金属組成を表2に示す。なお、2011年3月11日に起きた東日本大震災における原子力発電所事故により、福島県では一部の土壌に放射性物質が含まれている。 At the time of mixing PSC and radioactive material-contaminated soil, the influence of radioactive materials such as radioactive cesium 134 and 137 contained in the radioactive material-contaminated soil on the PSC was investigated by a laboratory test. In this test, radioactive material-contaminated soil (100 g of completely dried (OD) weight) collected in Iitate-mura, Fukushima Prefecture in the summer of 2012 was put in a polyethylene bag, and PSC (10 g, OD) in a mesh bag was radioactive. It was embedded in material-contaminated soil and left at 25 ° C. for 10 days. On the other hand, in the blank test, the radioactive material-contaminated soil (100 g, OD) and PSC (10 g, OD) were put in a polyethylene bag and mixed well, and then the test was performed under the same conditions. Radioactive cesium 134 and 137 of each radioactive substance-contaminated soil, PSC, pH, ion exchange capacity (CEC), metal composition of PSC before and after contamination were measured. Table 1 and FIG. 1 show the quality results of radioactive material-contaminated soil and PSC, and Table 2 shows the metal composition of PSC before and after contamination. In addition, due to the nuclear power plant accident in the Great East Japan Earthquake that occurred on March 11, 2011, some soils contained radioactive materials in Fukushima Prefecture.

図1に示すように、放置期間が長いほど放射性物質汚染土壌の放射性セシウム134及び137が減少し、逆にPSCの放射性セシウム134及び137が増加するため、放射性物質汚染土壌の放射性セシウムは、部分的にPSCに移転したと推定できる。   As shown in FIG. 1, the radioactive cesium 134 and 137 in the radioactive material contaminated soil is decreased and the radioactive cesium 134 and 137 in the PSC is increased as the standing period is longer. Can be estimated to have been transferred to PSC.

上記ラボテストによって10日間放置した結果を表1に示す。放射性物質汚染土壌にPSCを埋設した試験において、放射性物質汚染土壌の残留放射性セシウム134及び137の合計と、PSCに吸着した放射性セシウム134及び137との合計は、埋設試験前の放射性物質汚染土壌の放射性セシウム134及び137の合計と、ほぼ同等の値となった。一方で、放射性物質汚染土壌とPSCとを均一に混合したブランク試験では、混合物の放射性セシウム134及び137の合計が、試験前の放射性物質汚染土壌の放射性セシウム134及び137の合計よりも低い。そのため、放射性物質汚染土壌の除染効率の向上を図るためには、PSCが、可能な限りに多くの放射性物質汚染土壌と接触することが望ましいことがわかる。さらに、汚染後のPSCは汚染前に比べ、pH、陽イオン交換容量(CEC)が共に下がり、PSCが放射性物質汚染土壌の放射性セシウム134及び137とのイオン交換反応を行うこともわかる。   The results of standing for 10 days by the lab test are shown in Table 1. In the test in which PSC was embedded in radioactive material contaminated soil, the total of residual radioactive cesium 134 and 137 in the radioactive material contaminated soil and the total of radioactive cesium 134 and 137 adsorbed in the PSC was the same as that of the radioactive material contaminated soil before the embedded test. The total of radioactive cesium 134 and 137 was almost equivalent. On the other hand, in the blank test in which the radioactive material contaminated soil and PSC are uniformly mixed, the total of the radioactive cesium 134 and 137 of the mixture is lower than the total of the radioactive cesium 134 and 137 of the radioactive material contaminated soil before the test. Therefore, in order to improve the decontamination efficiency of radioactive material contaminated soil, it can be seen that it is desirable that the PSC is in contact with as much radioactive material contaminated soil as possible. Further, it can be seen that the PSC after the contamination has a lower pH and cation exchange capacity (CEC) than before the contamination, and the PSC undergoes an ion exchange reaction with the radioactive cesium 134 and 137 of the radioactive material contaminated soil.

Figure 2016020884
Figure 2016020884

上記の変化に加えて、表2に示すように、PSCのうち、塩素、硫黄、カリウム、バリウム、銅、マグネシウム、カルシウム、鉄等の構成要素が減少した。したがって、カリウム、バリウム、銅、マグネシウム、カルシウム、鉄等の金属塩化合物が、放射性セシウム134及び137を含む放射性物質汚染土壌の放射性物質とのイオン交換を行ったと推定される。   In addition to the above changes, as shown in Table 2, constituent elements such as chlorine, sulfur, potassium, barium, copper, magnesium, calcium, and iron were reduced in PSC. Therefore, it is estimated that metal salt compounds, such as potassium, barium, copper, magnesium, calcium, and iron, performed ion exchange with the radioactive substance of the radioactive substance contaminated soil containing radioactive cesium 134 and 137.

Figure 2016020884
Figure 2016020884

元素の周期律表を基にセシウムは、ナトリウムやカリウムと同じアルカリ金属に分類され、これらの元素と同様に振る舞うことがわかっている。一方、原子力発電所事故や核実験等の核***反応から発生する放射性セシウムは大気中に分散し、土壌へ降下する。負荷電を持つ土壌はこれらの陽イオンのセシウムを引き付けて留める。特に、粘土鉱物の表面OH-基を含む負電荷で、降下した放射性セシウムを閉じ込める。これらは単なる物理的吸着現象である。(http://jssspn.jp/info/secretariat/4317.html)。 Based on the periodic table of elements, cesium is classified as the same alkali metal as sodium and potassium, and it is known that it behaves like these elements. On the other hand, radioactive cesium generated from nuclear fission reactions such as nuclear power plant accidents and nuclear tests disperses in the atmosphere and falls to the soil. Soil with negative charge attracts and retains these cationic cesiums. In particular, the radioactive cesium that falls is confined by the negative charge containing the surface OH - group of the clay mineral. These are just physical adsorption phenomena. (Http://jssspn.jp/info/secretariat/4317.html).

本実施形態では、土壌に吸着した放射性セシウムが、PSCの構成要素であるカリウム、バリウム、銅、マグネシウム、カルシウム、鉄等とのイオン交換を行い、結果としてPSCが放射性汚染されることが判明した。したがって、放射性物質汚染土壌の放射性セシウムは、PSCの多孔質粒状に単に物理的に吸着しないことが分かる。   In the present embodiment, it has been found that radioactive cesium adsorbed on soil performs ion exchange with potassium, barium, copper, magnesium, calcium, iron, and the like, which are constituent elements of PSC, and as a result, PSC is radioactively contaminated. . Therefore, it can be seen that the radioactive cesium in the radioactive material-contaminated soil does not simply physically adsorb to the PSC porous particles.

学術文献によれば、放射性ナトリウム23、放射性カルシウム40等は、粘土とのイオン交換を行うことが実験的に明らかにされている。また、粘土の放射性ナトリウム22は放射性ナトリウム23溶液と、粘土の放射性カルシウム39は放射性カルシウム40溶液とのイオン交換をする際、交換するイオン元素が、交換されるイオン元素よりも質量数が1ポイント低いことが分かる。(Ferris,A.P.,Jepson,W.B.,1975.The exchange capacities of kaolinite and the preparation of homoionic clays.Journal of Colloid and Interface Science,51(5),245−259)。   According to academic literature, it has been experimentally clarified that radioactive sodium 23, radioactive calcium 40 and the like exchange ions with clay. In addition, when the radioactive sodium 22 of the clay is exchanged with the radioactive sodium 23 solution and the radioactive calcium 39 of the clay is exchanged with the radioactive calcium 40 solution, the ionic element to be exchanged has a mass number of one point than the ionic element to be exchanged. It turns out that it is low. (Ferris, AP, Jeffon, WB, 1975. The exchange capaci- ties of kaolinite and the preparation of homology crys. Journal of Collide and 25, 5).

放射性セシウム134及び137は、上記のPSCのカリウム、バリウム、銅、マグネシウム、カルシウム、鉄等とのイオン交換を行う時の反応製品の特定、半減期等が未知である。さらに、前記の安定的金属が放射性セシウム134及び137とのイオン交換を行う際、Cu64、Fe59、Zn65、Ca47、Mg28等のアイソトープが生成されることも未知である。また、これらの重金属のアイソトープが発生する場合、放射性セシウム134及び137が、他のセシウムのアイソトープに変身することも未知であるが、放射性物質汚染土壌の放射性セシウム134及び137が減少することから、変身の可能性が高いと考えられる。   Regarding the radioactive cesium 134 and 137, the identification of the reaction product, the half-life, etc. are unknown when ion exchange of the above PSC with potassium, barium, copper, magnesium, calcium, iron or the like is performed. Furthermore, it is also unknown that isotopes such as Cu64, Fe59, Zn65, Ca47, and Mg28 are produced when the stable metal performs ion exchange with radioactive cesium 134 and 137. Moreover, when these heavy metal isotopes are generated, it is unknown that the radioactive cesiums 134 and 137 are transformed into other cesium isotopes, but the radioactive cesiums 134 and 137 in the radioactive material contaminated soil are reduced. There is a high possibility of transformation.

しかし、上記学術文献によれば放射性物質汚染土壌とPSCとを混合する際、放射性セシウム134がPSCへイオン交換され、安定的なセシウム133に壊変し、同様に、放射性セシウム137が半減期の短い放射性セシウム136に壊変すると推定される。この推定によれば、本実施形態で確認されたPSCとの接触による放射性物質汚染土壌の放射性セシウム134及び137の減少が解明可能になる。なお、セシウムは39種のアイソトープがあり、半減期において、放射性セシウム137及び134は、各々30年、2年、質量数の132、135m、136、138、138mは各々6.5日、53分、13.2日、33分、3分、その他のアイソトープの殆どは数秒から何分の一秒である。   However, according to the above academic literature, when mixing radioactive material-contaminated soil and PSC, radioactive cesium 134 is ion-exchanged into PSC and disintegrated into stable cesium 133. Similarly, radioactive cesium 137 has a short half-life. Presumed to be decayed to radioactive cesium 136. According to this estimation, it becomes possible to elucidate the reduction of radioactive cesium 134 and 137 in the radioactive material contaminated soil due to contact with the PSC confirmed in the present embodiment. In addition, cesium has 39 kinds of isotopes. In the half-life, radioactive cesium 137 and 134 are 30 years and 2 years, respectively, and mass numbers 132, 135 m, 136, 138 and 138 m are 6.5 days and 53 minutes, respectively. 13.2 days, 33 minutes, 3 minutes, most other isotopes are seconds to fractions of a second.

放射性セシウム134及び137と、PSCのカリウム、バリウム、銅、マグネシウム、カルシウム、鉄等とのイオン交換反応によれば、これらの金属をPSCにさらに増加することでイオン交換反応が増強され、その結果、放射性物質汚染土壌のPSCによる除染効率が向上する。この推測を確認するため、金属の塩化物、硫酸塩、及び、カリウムと鉄とが共に含まれたフェロシアン化カリウム化合物からなる群から選択される1または2以上の化合物をPSCに含浸させ、放射性物質汚染土壌の除染効果を調査した。なお、PSCの塩素、硫黄は、一般に単独で存在せず、前記の金属と結合して金属塩化合物を生成する。ただし、硫酸バリウム、硫酸カルシウム共殆ど水に溶解しないためこれらの化合物の実験を行わなかった。   According to the ion exchange reaction between radioactive cesium 134 and 137 and PSC potassium, barium, copper, magnesium, calcium, iron, etc., the ion exchange reaction is enhanced by further increasing these metals to PSC. In addition, the decontamination efficiency of radioactive material contaminated soil by PSC is improved. In order to confirm this assumption, PSC is impregnated with one or more compounds selected from the group consisting of metal chlorides, sulfates, and potassium ferrocyanide compounds containing both potassium and iron. The decontamination effect of contaminated soil was investigated. In addition, the chlorine and sulfur of PSC generally do not exist independently, and combine with the above metal to form a metal salt compound. However, since both barium sulfate and calcium sulfate hardly dissolved in water, these compounds were not tested.

塩化化合物、硫酸化合物、カリウムと鉄とが共に含まれたフェロシアン化カリウム化合物をPSCに含浸するには、PSCの使用重量と同等量のイオン交換水、あるいは蒸留水に、PSCの重量に対する0.5%以上10%以下の金属化合物量を溶解させる。これらの溶液にPSCを浸漬し、25oCで液がなくなるまで乾燥する。 In order to impregnate the PSC with a chloride compound, a sulfate compound, and a potassium ferrocyanide compound containing both potassium and iron, 0.5% of the weight of the PSC is added to ion-exchanged water or distilled water equivalent to the use weight of the PSC. % Or more and 10% or less of the metal compound amount is dissolved. PSC is immersed in these solutions and dried at 25 ° C. until no liquid is left.

下記に示すように、カリウム、バリウム、銅、マグネシウム、カルシウム、鉄等の塩化物のうち、塩化カリウムのみが使用可能である。一方で、カリウム、銅、マグネシウム、鉄等の硫酸塩のうち、カリウム、銅、マグネシウムが使用できる。これらの化合物の単独あるいは可能な6の組み合わせのうちの2以上の複数硫酸化合物が使用可能である。さらに、フェロシアン化カリウムも応用できる。金属の塩化物、硫酸塩及びフェロシアン化カリウムを組み合わせて使用する場合、これらの化合物の可能な120の組み合わせのうちの2以上の複数化合物が使用できる。   As shown below, of the chlorides such as potassium, barium, copper, magnesium, calcium, iron, etc., only potassium chloride can be used. On the other hand, potassium, copper, magnesium can be used among sulfates, such as potassium, copper, magnesium, and iron. These compounds can be used alone, or two or more of the six possible combinations can be used. Furthermore, potassium ferrocyanide can also be applied. When metal chlorides, sulfates and potassium ferrocyanide are used in combination, two or more of the 120 possible combinations of these compounds can be used.

PSCは、安定セシウム含有量が0.2ppmと微量であるが、安定セシウムと放射性セシウムとのイオン交換反応を確認する目的で、PSC重量に対する1%塩化セシウム、あいは1%硫酸セシウムを蒸留水に溶解し、PSCに含浸させた後、放射性物質汚染土壌との混合行い、除染効率を調査した。   PSC has a stable cesium content of 0.2 ppm, but for the purpose of confirming the ion exchange reaction between stable cesium and radioactive cesium, 1% cesium chloride or 1% cesium sulfate relative to the weight of PSC is distilled water. After being dissolved in and impregnated with PSC, it was mixed with radioactive material contaminated soil, and the decontamination efficiency was investigated.

次に、本発明の実施例を説明するが、本発明はこれらの実施例に何ら制限されるものではない。   Next, examples of the present invention will be described, but the present invention is not limited to these examples.

実験で使用した放射性物質汚染土壌は、2013年9月に福島県飯舘村で採取し、固形分が約85%になるまで風乾した。以下の実施例および参考例では、放射性物質汚染土壌(85g、OD)、PSC、金属化合物、またはフェロシアン化カリウム化合物が含浸されたPSC(金属塩名−PSC(例:CuSO4−PSC)と記す。)(15g、OD)の順でポリエチレン袋に入れ、よく混合し、25oCで、10日間放置した。放射性物質汚染土壌の放射性セシウム134及び137は、厚生労働省「緊急時における食品の放射線測定マニュアル」、文部科学省「ゲルマニウム半導体検出器によるγ線スペクトロメトリー」を基に、Canberra製同軸型ゲルマニウム検出器で測定した。 The radioactive material contaminated soil used in the experiment was collected in September 2013 in Iitate Village, Fukushima Prefecture, and air-dried until the solid content was about 85%. In the following examples and reference examples, PSC impregnated with radioactive material-contaminated soil (85 g, OD), PSC, metal compound, or potassium ferrocyanide compound (metal salt name-PSC (example: CuSO 4 -PSC)) is described. ) (15 g, OD) in a polyethylene bag, mixed well, and left at 25 ° C. for 10 days. Radioactive cesium 134 and 137 in soil contaminated with radioactive material is a coaxial germanium detector manufactured by Camberra based on the Ministry of Health, Labor and Welfare “Manual for Measuring Radiation of Foods in Emergency” and Ministry of Education, Culture, Sports, Science and Technology “γ-ray spectrometry using germanium semiconductor detector”. Measured with

<参考例1>
放射性物質汚染土壌(100g、OD)、1%塩化カリウム(土壌重量に対する%)の順でポリエチレン袋に入れる。同様に、放射性物質汚染土壌(100g、OD)、1%塩化セシウム(土壌重量に対する%)の順で別のポリエチレン袋に入れる。ポリエチレン袋の内容をそれぞれよく混合し、25oCで、10日間放置した後、放射性セシウム134及び137を測定した。
<Reference Example 1>
Place in a polyethylene bag in the order of radioactive material contaminated soil (100 g, OD), 1% potassium chloride (% of soil weight). Similarly, put in another polyethylene bag in the order of radioactive material contaminated soil (100 g, OD), 1% cesium chloride (% of soil weight). The contents of the polyethylene bag were mixed well and left at 25 ° C. for 10 days, and then radioactive cesium 134 and 137 were measured.

Figure 2016020884
Figure 2016020884

表3に示すように、市販の塩化カリウム、塩化セシウムを、PSCに含浸させずにそのままの状態で放射性物質汚染土壌と混合した場合、放射性セシウム134及び137の合計が上がった。放射性セシウム137は僅かに上がったが、放射性セシウム134が大幅に増加したため、これらの薬品が放射性セシウム134の分解を妨害したと推定される。   As shown in Table 3, when commercially available potassium chloride and cesium chloride were mixed with radioactive material-contaminated soil as it was without impregnating PSC, the total of radioactive cesium 134 and 137 increased. Although the radioactive cesium 137 rose slightly, it is presumed that these chemicals prevented the decomposition of the radioactive cesium 134 because the radioactive cesium 134 increased significantly.

<実施例1>
6%CaCl2−PSCの調整は、次の手順で実施した。CaCl2・2H2O(23.838g)を蒸留水(300ml)に溶解し、次いで、浅い容器の中のPSC(300g、OD)上に注ぎ、25OCで、24〜48時間乾燥を行い、その間容器を2〜3回振った。同様の方法にて、KCl−PSC、BaCl2−PSC、MgCl2−PSC、CsCl−PSCを作成した。放射性物質汚染土壌(85g、OD)、前記塩化金属化合物−PSC(15g、OD)の順でポリエチレン袋に入れ、均一に混合し、25oCで、10日間放置した。ブランクテストは、放射性物質汚染土壌(85g、OD)とPSC(15g、OD)をポリエチレン袋の中で均一に混合し、同じ条件で試験を行った。その後、放射性セシウム134及び137を測定した。結果を表4に示す。
<Example 1>
Adjustment of 6% CaCl 2 -PSC was carried out by the following procedure. CaCl 2 · 2H 2 O (23.838 g) was dissolved in distilled water (300 ml), then poured onto PSC (300 g, OD) in a shallow container and dried at 25 O C for 24-48 hours. In the meantime, the container was shaken 2-3 times. In a similar manner were prepared KCl-PSC, BaCl 2 -PSC, MgCl 2 -PSC, the CsCl-PSC. Radioactive material contaminated soil (85 g, OD) and the above metal chloride compound-PSC (15 g, OD) were put in a polyethylene bag, mixed uniformly, and left at 25 ° C. for 10 days. In the blank test, radioactive material-contaminated soil (85 g, OD) and PSC (15 g, OD) were uniformly mixed in a polyethylene bag, and the test was performed under the same conditions. Thereafter, radioactive cesium 134 and 137 were measured. The results are shown in Table 4.

Figure 2016020884
Figure 2016020884

ブランクテストに比べ、検討した5種の塩化金属−PSCのうち、塩化カリウム−PSCのみが、除染率が高いことが見出された。これは、上述したようにカリウム、セシウムとも元素周期律表の同じ列1Aにあり、お互いに置き換えやすいことによる原因と考えられる。これと表3の1%KCl薬品の結果から、イオン交換反応が起きるためには支持体が必要とさせることが分かる。   Of the five types of metal chloride-PSC studied, only potassium chloride-PSC was found to have a higher decontamination rate than the blank test. As described above, this is considered to be due to the fact that both potassium and cesium are in the same column 1A of the periodic table of elements and can be easily replaced with each other. From this and the results for 1% KCl chemicals in Table 3, it can be seen that a support is required for the ion exchange reaction to occur.

6%KCl−PSC及び6%BaCl2−PSCが、5%KCl−PSC及び1%BaCl2−PSCの各々に比べて除染率が低いため、塩素基が除染反応を遅角したことが分かる。一方、6%CaCl2−PSC、1%BaCl2−PSC、6%MgCl2−PSC、5%CsCl−PSCは、ブランクテストより除染率が劣ったため、カルシウム、バリウム、マグネシウム、セシウムの濃度が高い場合、除染反応が妨害されることが分かる。 Since 6% KCl-PSC and 6% BaCl 2 -PSC have lower decontamination rates than 5% KCl-PSC and 1% BaCl 2 -PSC, respectively, the chlorine group retarded the decontamination reaction. I understand. On the other hand, 6% CaCl 2 -PSC, 1% BaCl 2 -PSC, 6% MgCl 2 -PSC, and 5% CsCl-PSC have a lower decontamination rate than the blank test, so the concentrations of calcium, barium, magnesium, and cesium are low. When it is high, it can be seen that the decontamination reaction is hindered.

<実施例2>
1%MgSO4−PSCは次の方法で調整した。硫酸マグネシウム(MgSO4、3g)を蒸留水(300ml)に溶解し、次いで浅い容器の中のPSC(300g、OD)上に注ぎ、25OCで、24〜48時間乾燥を行い、その間容器を2〜3回振った。同様な方法により、硫酸カリウムでK2SO4−PSCを、FeSO4・7H2OでFeSO4−PSCを、ZnSO4・7H2OでZnSO4−PSCを、CuSO4・5H2OでCuSO4−PSCを、硫酸セシウムでCsSO4−PSCを、それぞれ作成した。放射性物質汚染土壌(85g、OD)、硫酸金属塩−PSC(15g、OD)の順でポリエチレン袋に入れ、均一に混合し、25oCで、10日間放置した。ブランクテストは、放射性物質汚染土壌(85g、OD)とPSC(15g、OD)とをポリエチレン袋の中で均一に混合し、同じ条件で試験を行った。その後、放射性セシウム134と137の測定を行った。結果を表5に示す。
<Example 2>
1% MgSO 4 -PSC was prepared by the following method. Magnesium sulfate (MgSO 4 , 3 g) is dissolved in distilled water (300 ml) and then poured onto PSC (300 g, OD) in a shallow container and dried at 25 O C for 24-48 hours while the container is Shake 2-3 times. The same manner, CuSO the K 2 SO 4 -PSC with potassium sulfate, the FeSO 4-PSC with FeSO 4 · 7H 2 O, the ZnSO 4-PSC with ZnSO 4 · 7H 2 O, with CuSO 4 · 5H 2 O 4- PSC and CsSO 4 -PSC were prepared with cesium sulfate, respectively. Radioactive material-contaminated soil (85 g, OD) and sulfate metal salt-PSC (15 g, OD) were put in a polyethylene bag, mixed uniformly, and left at 25 ° C. for 10 days. In the blank test, radioactive material-contaminated soil (85 g, OD) and PSC (15 g, OD) were uniformly mixed in a polyethylene bag, and the test was performed under the same conditions. Thereafter, radioactive cesium 134 and 137 were measured. The results are shown in Table 5.

Figure 2016020884
Figure 2016020884

ブランクテストに比べ、検討した6種の金属硫酸塩−PSCのうち、硫酸セシウムのみが除染率が劣った。これと表4の塩化セシウム除染率結果を合わせると、安定セシウムは放射性セシウムの除染反応を妨害することが分かる。硫酸鉄及び硫酸亜鉛の除染率は、ブランクテストと同等の値であるため、これらの金属硫酸塩をPSCに含浸する必要がなくなる。一方、硫酸マグセシウム、硫酸銅、硫酸カリウムは、ブランクテストより除染率が優れるため、PSCに含浸すると放射性物質汚染土壌の除染率を改善することができる。   Of the six types of metal sulfate-PSCs examined, only the cesium sulfate was inferior in decontamination rate compared to the blank test. When this is combined with the results of cesium chloride decontamination in Table 4, it can be seen that stable cesium interferes with the decontamination reaction of radioactive cesium. Since the decontamination rate of iron sulfate and zinc sulfate is the same value as the blank test, it is not necessary to impregnate PSC with these metal sulfates. On the other hand, since magnesium sulfate, copper sulfate, and potassium sulfate have a higher decontamination rate than the blank test, impregnation into PSC can improve the decontamination rate of radioactive material contaminated soil.

<実施例3>
1%フェロシアン化カリウム−PSCは次の方法で調整した。K4[Fe(CN)6]3H2O(3.385g)を蒸留水(360ml)に溶解し、次いで浅い容器の中のPSC(300g、OD)上に注ぎ、25OCで、24〜48時間乾燥を行い、その間容器を2〜3回振った。放射性物質汚染土壌(85g、OD)、フェロシアン化カリウム−PSC(15g、OD)の順でポリエチレン袋に入れ、均一に混合し、25oCで、10日間放置した。ブランクテストは、放射性物質汚染土壌(85g、OD)とPSC(15g、OD)とをポリエチレン袋の中で均一に混合し、同じ条件で試験を行った。その後、放射性セシウム134と137の測定を行った。結果を表6に示す。
<Example 3>
1% potassium ferrocyanide-PSC was prepared by the following method. K 4 [Fe (CN) 6 ] 3H 2 O (3.385 g) was dissolved in distilled water (360 ml) and then poured onto PSC (300 g, OD) in a shallow vessel, 25 O C at 24- Drying was performed for 48 hours, during which the container was shaken 2-3 times. Radioactive material contaminated soil (85 g, OD) and ferrocyanide potassium-PSC (15 g, OD) were put in a polyethylene bag, mixed uniformly, and left at 25 ° C. for 10 days. In the blank test, radioactive material-contaminated soil (85 g, OD) and PSC (15 g, OD) were uniformly mixed in a polyethylene bag, and the test was performed under the same conditions. Thereafter, radioactive cesium 134 and 137 were measured. The results are shown in Table 6.

Figure 2016020884
Figure 2016020884

フェロシアン化カリウム−PSCは、ブランクテストに比べ除染率が高いことが見出された。これは、上述したように放射性セシウムとのイオン交換を行うカリウム、鉄等がフェロシアン化カリウムに共に存在することによることが原因と考えられる。したがって、フェロシアン化カリウムはPSCに含浸すると放射性物質汚染土壌の除染率を改善することができる。   It was found that potassium ferrocyanide-PSC has a higher decontamination rate than the blank test. This is thought to be due to the fact that potassium, iron, and the like that exchange ions with radioactive cesium are present in potassium ferrocyanide as described above. Accordingly, when PSC is impregnated with potassium ferrocyanide, the decontamination rate of radioactive material contaminated soil can be improved.

表4、5、6の結果を検討すると、放射性物質汚染土壌の除染率を向上するためには、カリウムの塩化物、マグネシウムの硫酸塩、カリウムの硫酸塩、銅の硫酸塩、フェロシアン化カリウム化合物をPSCに含浸すべきである。また、放射性物質汚染土壌の除染率の相乗効果を図るには、塩化カリウム、硫酸マグネシウム、硫酸カリウム、硫酸銅、フェロシアン化カリウムの可能な120の組み合わせ(5種類であるため、組み合わせは、1×2×3×4×5=120となる。)のうちの2以上の複数化合物をPSCに含浸すべきである。   Examining the results of Tables 4, 5 and 6, in order to improve the decontamination rate of radioactive material contaminated soil, potassium chloride, magnesium sulfate, potassium sulfate, copper sulfate, potassium ferrocyanide compound Should be impregnated into the PSC. In order to achieve a synergistic effect on the decontamination rate of radioactive material contaminated soil, 120 possible combinations of potassium chloride, magnesium sulfate, potassium sulfate, copper sulfate and potassium ferrocyanide (there are 5 types, so the combination is 1 × 2 × 3 × 4 × 5 = 120), and the PSC should be impregnated with two or more compounds.

上記したとおり、本実施形態によれば、塩化カリウム、硫酸マグネシウム、硫酸カリウム、硫酸銅、フェロシアン化カリウムの単独または可能な120の組み合わせのうちの2以上の複数化合物をPSCに含浸し、得られた金属塩−PSCを放射性物質汚染土壌と混合することにより、未処理PSCより除染率が大幅に改善される。これらの金属塩化合物は簡単に調整することができ、PSCにも含浸しやすく、且つ安価な市販品であるため、コスト、実用性を総合的に満たす技術である。さらに、生産される米、野菜等の農産物の放射性セシウム134及び137を、簡単に日本基準値より低値にすることが可能である。   As described above, according to this embodiment, PSC was impregnated with two or more compounds of potassium chloride, magnesium sulfate, potassium sulfate, copper sulfate, potassium ferrocyanide alone or two or more possible combinations of 120. By mixing the metal salt-PSC with radioactive material contaminated soil, the decontamination rate is significantly improved over the untreated PSC. Since these metal salt compounds can be easily adjusted, are easily impregnated into PSC, and are inexpensive commercial products, they are technologies that comprehensively satisfy cost and practicality. Furthermore, the radioactive cesiums 134 and 137 of agricultural products such as rice and vegetables produced can be easily made lower than the Japanese standard value.

以上、本発明の実施形態を詳述したが、本発明は上記実施形態に限定されるものではない。そして本発明は、特許請求の範囲に記載された事項を逸脱することがなければ、種々の設計変更を行うことが可能である。   As mentioned above, although embodiment of this invention was explained in full detail, this invention is not limited to the said embodiment. The present invention can be modified in various ways without departing from the scope of the claims.

Claims (5)

イオン交換可能な金属の塩化物、硫酸塩、及び鉄‐シアン化合物からなる群から選択される1または2以上の化合物を、ペーパースラッジからなる多孔質粒状炭化焼成物に含浸させ、この多孔質粒状炭化焼成物と放射性物質汚染土壌とを混合し、前記放射性物質汚染土壌の放射性セシウム134及び137とのイオン交換を行う、
ことを特徴とする放射性物質汚染土壌の除染方法。
One or two or more compounds selected from the group consisting of ion-exchangeable metal chlorides, sulfates, and iron-cyanide compounds are impregnated into a porous granular carbonized fired article made of paper sludge, and the porous granular form is impregnated. Carbonized fired product and radioactive material contaminated soil are mixed, and ion exchange with radioactive cesium 134 and 137 of the radioactive material contaminated soil is performed.
A decontamination method for radioactive material contaminated soil.
前記多孔質粒状炭化焼成物に含浸させる塩化物が塩化カリウムであり、この塩化カリウムが、前記多孔質粒状炭化焼成物の重量の0.5%以上5%以下である、
ことを特徴とする請求項1に記載された放射性物質汚染土壌の除染方法。
The chloride impregnated in the porous granular carbonized fired product is potassium chloride, and the potassium chloride is 0.5% or more and 5% or less of the weight of the porous granular carbonized fired product,
The method for decontaminating radioactive material-contaminated soil according to claim 1.
前記多孔質粒状炭化焼成物に含浸させる硫酸塩が、硫酸カリウム、硫酸マグネシウム、及び硫酸銅からなる群から選択される1または2以上の硫酸塩であり、前記硫酸カリウムが前記多孔質粒状炭化焼成物の重量の1%以上5%以下、前記硫酸マグネシウムが前記多孔質粒状炭化焼成物の重量の1%以上5%以下、及び前記硫酸銅が前記多孔質粒状炭化焼成物の重量の1%である、
ことを特徴とする請求項1または請求項2に記載された放射性物質汚染土壌の除染方法。
The sulfate impregnated in the porous granular carbonized product is one or more sulfates selected from the group consisting of potassium sulfate, magnesium sulfate, and copper sulfate, and the potassium sulfate is calcined with the porous granular carbonized product. 1% to 5% of the weight of the product, the magnesium sulfate is 1% to 5% of the weight of the porous granular carbonized fired product, and the copper sulfate is 1% of the weight of the porous granular carbonized fired product is there,
The method for decontamination of radioactive material-contaminated soil according to claim 1 or claim 2, wherein
前記多孔質粒状炭化焼成物に含浸させる鉄‐シアン化合物がフェロシアン化カリウムであり、このフェロシアン化カリウムが、前記多孔質粒状炭化焼成物の重量の0.5%以上5%以下である、
ことを特徴とする請求項1から請求項3のいずれか1項に記載された放射性物質汚染土壌の除染方法。
The iron-cyanide compound impregnated into the porous granular carbonized fired product is potassium ferrocyanide, and the potassium ferrocyanide is 0.5% or more and 5% or less of the weight of the porous granular carbonized fired product,
The method for decontamination of radioactive substance-contaminated soil according to any one of claims 1 to 3, wherein the soil is contaminated with radioactive material.
塩化カリウムが、ペーパースラッジからなる多孔質粒状炭化焼成物の重量の0.5%以上5%以下であり、
硫酸カリウムが、前記多孔質粒状炭化焼成物の重量の1%以上5%以下であり、
硫酸マグネシウムが、前記多孔質粒状炭化焼成物の重量の1%以上5%以下であり、
硫酸銅が、前記多孔質粒状炭化焼成物の重量の1%であり、
フェロシアン化カリウムが、前記多孔質粒状炭化焼成物の重量の0.5%以上5%以下であり、
前記塩化カリウム、前記硫酸カリウム、前記硫酸マグネシウム、前記硫酸銅、及びフェロシアン化カリウムからなる群から選択される1または2以上の化合物を、前記多孔質粒状炭化焼成物に含浸させ、この多孔質粒状炭化焼成物と放射性物質汚染土壌とを混合し、前記放射性物質汚染土壌の放射性セシウム134及び137とのイオン交換を行う、
ことを特徴とする放射性物質汚染土壌の除染方法。
Potassium chloride is 0.5% or more and 5% or less of the weight of the porous granular carbonized fired product made of paper sludge,
Potassium sulfate is 1% or more and 5% or less of the weight of the porous granular carbonized fired product,
Magnesium sulfate is 1% or more and 5% or less of the weight of the porous granular carbonized fired product,
Copper sulfate is 1% of the weight of the porous granular carbonized fired product,
The potassium ferrocyanide is 0.5% or more and 5% or less of the weight of the porous granular carbonized fired product,
The porous granular carbonized product is impregnated with one or more compounds selected from the group consisting of the potassium chloride, the potassium sulfate, the magnesium sulfate, the copper sulfate, and the potassium ferrocyanide. Mixing the fired product and radioactive material-contaminated soil, and performing ion exchange with the radioactive cesium 134 and 137 of the radioactive material-contaminated soil,
A decontamination method for radioactive material contaminated soil.
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