JP4154453B2 - Separation method of rare earth elements and actinoid elements and extract thereof - Google Patents
Separation method of rare earth elements and actinoid elements and extract thereof Download PDFInfo
- Publication number
- JP4154453B2 JP4154453B2 JP2002269233A JP2002269233A JP4154453B2 JP 4154453 B2 JP4154453 B2 JP 4154453B2 JP 2002269233 A JP2002269233 A JP 2002269233A JP 2002269233 A JP2002269233 A JP 2002269233A JP 4154453 B2 JP4154453 B2 JP 4154453B2
- Authority
- JP
- Japan
- Prior art keywords
- tpen
- extract
- d2ehpa
- rare earth
- elements
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Images
Landscapes
- Extraction Or Liquid Replacement (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、希土類元素（スカンジウム、イットリウム、およびランタノイド）とアクチノイド元素とを少ない処理液量で簡単かつ安定に効率よく分離する技術に関する。
【０００２】
使用済み核燃料を再処理した後に発生する高レベル放射性廃液には種々の放射性元素が含まれている。なかでも長寿命のアクチノイドは毒性が長期間にわたって存在するため、これを放射性廃液から分離し、核変換処理などを安全に行うことができる確実な分離方法が求められている。本発明はかかる処分法に必須の技術であり、本発明の処理技術によれば、高レベル廃液に多量に含まれている希土類元素から少量のアメリシウムやキュリウムなどのアクチノイド元素を効率よく回収することができる。
【０００３】
【従来の技術】
希土類元素とアクチノイド元素とを分離する方法として以下の方法が従来から知られている。
（イ）Ｄ２ＥＨＰＡとＤＴＰＡを用いる方法
ジ-2-エチルヘキシルリン酸(D2EHPA)とジエチレントリアミンN、N、N'、N"、N'"-5酢酸(DTPA)とを含む抽出液を用いて三価希土類元素から三価アクチノイド元素を抽出分離することができる。しかし、この方法は処理液のｐＨの依存性が大きいために処理液のｐＨを厳密に調整しなければならず、乳酸などの緩衝剤を必要とするなど処理操作が面倒である。
【０００４】
（ロ）チオシアンイオン、アジドイオンを用いる方法
チオシアンイオン、アジドイオンを用いることによって三価希土類元素と三価アクチノイド元素とを分離することが出来る。しかし、この方法は数モル程度の高濃度の塩を添加する必要があり、二次廃棄物の量も多く、しかもその化学的安定性が低いと云う問題がある。
【０００５】
（ハ）ＣＹＡＮＥＸを用いる方法
ジ(2、4、4-トリメチルフェニル)ジチオリン酸(CYANEX301:カナダCYTEC社製品)を用いてアメリシウムとユーロピウムとを分離することができる。しかし、この方法は上記処理液(CYANEX301)を９９％以上にまで精製して使用する必要があり、しかも酸性溶液に対して化学的安定性が低いなどの問題がある。
【０００６】
（ニ）ＴＰＴＺを用いる方法
トリス〔2、4、6-(2−ピリジル）〕1、3、5-トリアジン（ＴＰＴＺ）をジノニルナフタレンスルフォン酸（ＨＤＮＮＳ）と共に用いてアメリシウムとユーロピウムを分離することができるが、このＨＤＮＮＳは界面活性剤であるために有機相と水相の分離が非常に悪いという問題がある。
【０００７】
（ホ）ＢＴＰを用いる方法
ビストリアジニルピリジン（ＢＴＰ）と呼ばれる一連の化合物（正式名：2、6-ジ[5、6-アルキル-1、2、4-トリアジン-3-イル]ピリジン）を用いて、アメリシウムとユーロピウムを分離することが提案されている。しかし、この化合物は化学的安定性が非常に低いために長期間の使用に耐えず、また溶解に適した溶媒が非常に少ないという問題がある。
【０００８】
【発明の解決課題】
本発明は、希土類元素とアクチノイド元素の分離方法における従来の上記問題を解決したものであり、少ない処理液量で簡単かつ安定に効率よく希土類元素とアクチノイド元素とを分離する技術を提供するものである。
【０００９】
本発明者等は、Ｄ２ＥＨＰＡにＴＰＥＮを助剤として加えた抽出液について、アメリシウム(Ａｍ)とユーロピウム(Ｅｕ)に対する抽出効果を先に検討したところ、抽出剤としてＤ２ＥＨＰＡを用いた場合、極低濃度のＤ２ＥＨＰＡが存在するだけでも、Ｄ２ＥＨＰＡの抽出能がＴＰＥＮの錯形成能に比べて十分に大いので、ＡｍとＥｕの分配比に対するＴＰＥＮの影響は見られないとの知見を得た。ところが、さらに検討を進めたところ、Ｄ２ＥＨＰＡとＴＰＥＮを併用した抽出液において、ｐＨ３以上の液性下ではＴＰＥＮの影響が現れ、ＡｍとＥｕの分配比の差が大きくなることを見出した。本発明はこの知見に基づくものである。
【００１０】
【課題を解決する手段】
本発明は、Ｎ、Ｎ、Ｎ’、Ｎ”−テトラメチルピリジルエチレンジアミン（ＴＰＥＮ）とジ−２−エチルヘキシル−リン酸（Ｄ２ＥＨＰＡ）とを含む抽出液を用い、ｐＨ３〜６の液性下で、希土類元素とアクチノイド元素を抽出分離することを特徴とする分離方法に関する。
【００１１】
また、本発明は、Ｎ、Ｎ、Ｎ’、Ｎ”−テトラメチルピリジルエチレンジアミン（ＴＰＥＮ）とジ−２−エチルヘキシル−リン酸（Ｄ２ＥＨＰＡ）とを含み、ｐＨ３〜６の液性下で用いられることを特徴とする希土類元素とアクチノイド元素の抽出分離液に関する。
【００１２】
以下、本発明を実施形態に基づいて具体的に説明する。
本発明は、（イ）Ｎ、Ｎ、Ｎ’、Ｎ”−テトラメチルピリジルエチレンジアミン（ＴＰＥＮ）とジ−２−エチルヘキシル−リン酸（Ｄ２ＥＨＰＡ）とを含む抽出液を用い、ｐＨ３〜６の液性下で、希土類元素とアクチノイド元素を抽出分離することを特徴とする分離方法、および（ロ）Ｎ、Ｎ、Ｎ’、Ｎ”−テトラメチルピリジルエチレンジアミン（ＴＰＥＮ）とジ−２−エチルヘキシル−リン酸（Ｄ２ＥＨＰＡ）とを含み、ｐＨ３〜６の液性下で用いられることを特徴とする希土類元素とアクチノイド元素の抽出分離液に関する。
【００１３】
ＴＰＥＮは化学的に安定であり、しかも高純度のものを容易に合成することができるので使用時に精製する必要がなく、かつ少い使用量で顕著な分離効果が得られる。従って二次廃棄物の発生を抑えることができる。また、各種の溶媒や市販の抽出剤等とＴＰＥＮとを組み合わせることによって、溶解性および相分離性に優れた効果を得ることができ、さまざまな分離条件に対応することができる。
【００１４】
溶媒や他の抽出剤との組み合わせとしては、例えば、ＴＰＥＮと共にジ−２−エチルヘキシル−リン酸（Ｄ２ＥＨＰＡ）を添加したものが好ましい。具体的には、アルコールなどの有機溶媒にＤ２ＥＨＰＡの２モルに対してＴＰＥＮの１モルを溶解させた抽出液を用いると良い。ＴＰＥＮと共にＤ２ＥＨＰＡを含む抽出液をｐＨ３〜６の液性下で用いることによって、希土類元素に対してアクチノイド元素の高い分配比を達成し、優れた分離効果を得ることができる。
【００１５】
なお、参考例として、ＴＰＥＮと共にジ（２、４、４−トリメチルフェニル）ジチオリン酸を有機溶媒に添加した抽出液を用いてもよい。この抽出液をｐＨ３以上の液性下で用いると、ＴＰＥＮの濃度が１〜１０モル濃度の範囲においてＴＰＥＮ濃度の上昇に伴ってアメリシウムの分配比が概ね高くなり、一方、ユーロピウムの分解比は次第に減少するので、優れた分離効果を得ることができる。
【００１６】
ＴＰＥＮを溶解する有機溶媒はアルコールやニトロベンゼンなどを用いることができる。なお、ニトロベンゼンにＴＰＥＮを溶解したものはＤ２ＥＨＰＡ等を併用しなくてもＴＰＥＮ単独で希土類元素とアクチノイド元素とを分離することができる。
【００１７】
ＴＰＥＮと共にジ−２−エチルヘキシル−リン酸（Ｄ２ＥＨＰＡ）を有機溶媒に溶解させた抽出液、あるいはＴＰＥＮと共にジ（２、４、４−トリメチルフェニル）ジチオリン酸を有機溶媒に溶解させた抽出液、またはニトロベンゼンにＴＰＥＮを溶解させた抽出液をｐＨ３以上の液性下で用い、この抽出液を希土類元素およびアクチノイド元素を含む水溶液と混合して該抽出液にアクチノイド元素を移行させて希土類元素と分離する。なお、ｐＨが３より低い領域（酸性側）ではアクチノイド元素と希土類元素の分配比が近いが、これより中性側（図３に示すようにｐＨ３〜６の領域）ではアクチノイド元素の分配比が希土類元素の分配比よりも格段に高く維持されるので、優れた分離効果を得ることができる。なお、このｐＨ調整は上記水溶液の初期ｐＨを概ね３以上に調整すれば高い分配比が維持されるので、これより厳密なｐＨ調整を行う必要はない。従ってｐＨ調整が容易である。
【００１８】
ＴＰＥＮを含む上記抽出液を用いれば、実施例に示すように、少ない処理液量でもアクチノイド元素について優れた分離効果を得ることができる。また、抽出回数や日数を繰り返して高い分配係数を維持し、長期間安定な分離効果を得ることができる。
【００１９】
【実施例】
以下、本発明を実施例によって具体的に示す。なお、本発明の範囲はこの実施例によって限定されない。
〔実施例１〕
１-オクタノールにジ(2-エチルヘキシル)リン酸(D2EHPA)のみを溶解した抽出液(Ｉ)０.５mlを調製した。また、１-オクタノールにＤ２ＥＨＰＡとＴＰＥＮとを２対１に混合溶解した抽出液(II)０.５mlとを調製した。さらに、０.１Ｍ硝酸アンモニウム、１mＭ硝酸ユーロピウム、トレーサ量(10-9M程度)のユーロピウム152、およびトレーサ量(10-9M程度)のアメリシウム241を含むｐＨ４程度の水溶液０.５mlを調製した。この水溶液と上記抽出液(Ｉ)、および上記水溶液と上記抽出液(II)とをそれぞれマイクロチューブに入れて３０分間振蘯した後、有機相と水相とに分離し、各相に含まれるユーロピウム152とアメリシウム241の放射線を測定して各元素の分配比（水相に残留した量に対する有機相に移行した量の比率）を求めた。その結果を図１(Ａ)(Ｂ)に示す。図１(Ａ)に示すように、Ｄ２ＥＨＰＡを単独に用いたものはユーロピウムとアメリシウムの分配比が接近しており、分離効果が低いが、Ｄ２ＥＨＰＡとＴＰＥＮを組み合わせた溶液を用いた図１(Ｂ)のものは、アメリシウムの分配比がユーロピウムのそれよりも格段に大きく、従って優れた分離効果が得られることがわかる。
【００２０】
〔実施例２〕
１-オクタノールにジ(2-エチルヘキシル)リン酸(D2EHPA)と１mMのＴＰＥＮを溶解した抽出液０.５mlを調製した。一方、０.１４Ｍ硝酸アンモニウムと各種希土類元素を２０ppmづつ含むｐＨ４程度の水溶液０.５mlを調製し、この水溶液と上記抽出液とをマイクロチューブに入れて３０分間振蘯した後、有機相と水相とを分離し、各相に含まれる各希土類元素の濃度を測定して分配比を求めた。その結果を図２に示す。図示するように、アメリシウムの分配比が２２であるのに対してＬａ〜Ｇｄの希土類元素の分配比は約０.５以下であり、分配比の差が大きい。従って上記抽出液を用いればアメリシウムと希土類元素とを効果的に分離できることがわかる。
【００２１】
〔実施例３〕
１-オクタノールに２mMのジ(2-エチルへキシル)リン酸(D2EHPA)と１mMのＴＰＥＮとを溶解した抽出液０.５mlを調製した。一方、０.１Ｍ硝酸アンモニウム、トレーサ量(10-9M程度)のユーロピウム152、トレーサ量(10-9M程度)のアメリシウム241を含む水溶液０.５mlを調製し、この水溶液と上記抽出液とをマイクロチューブに入れて３０分間振蘯した後、有機相と水相に分離し、各相に含まれるユーロピウム152およびアメリシウム241の放射線を測定して各元素の分配比を得た。このとき、上記水溶液は予めｐＨを２から６程度に調整したものを用い、分配比に対する初期ｐＨの依存性を調べた。その結果を図３に示す。図示するように、ｐＨ３以上の範囲では何れもアメリシウムがユーロピウムに対して高い分配比を維持しており、従って、これらの元素を含有する水溶液については初期ｐＨを概ね３以上に調整すれば、これより中性側の領域では厳密なｐＨ調整を必要とせずに優れた分離効果が得られることがわかる。また、従ってｐＨ調整の緩衝剤も不要である。
【００２２】
〔実施例４〕
実施例３と同様のユーロピウム152とアメリシウム241を含む水溶液とＤ２ＥＨＰＡおよびＴＰＥＮを含む抽出液とを用い、これらをマイクロチューブに入れて３０分間振蘯した後、有機相と水相に分離し、各相に含まれるユーロピウム152とアメリシウム241の放射線を測定して各元素の分配比を得た。この操作を、繰り返し数日間行い、接触時間に対する分配比の安定性を調べた。その結果を図４に示す。図示するように、繰り返し接触してもアメリシウムの分配比は安定しており、接触時間に依存しないことがわかる。
【００２３】
〔参考例５〕
１−オクタノールに純度９９．５％以上に精製したジ（２、４、４−トリメチルフェニル）ジチオリン酸（商品名：ＣＹＡＮＥＸ ３０１）１０ｍＭと各濃度のＴＰＥＮとを溶解した抽出液０．５ｍｌを調製した。この抽出液と０．１Ｍ硝酸アンモニウムおよび、１ｍＭ硝酸ユーロピウムを含みかつトレーサー量（１０−９Ｍ程度）のユーロピウム１５２とトレーサー量（１０−９Ｍ程度）のアメリシウム２４１を含む水溶液０．５ｍｌとをマイクロチューブに混合して３０分間振とうした。振とう後、各試料溶液について有機相と水相とを分離し、それぞれの相のユーロピウム１５２、およびアメリシウム２４１の放射線を測定してその分配比を求め、分配比に対するＴＰＥＮ濃度の依存性を調べた。なお、水溶液は予めｐＨを４程度に調整したものを用いた。その結果を図５に示す。本実施例ではＴＰＥＮ濃度がゼロの場合にはアメリシウムとユーロピウムの分配比はほぼ等しいが、ＴＰＥＮ濃度の上昇に伴ってアメリシウムの分配比が大きくなり、一方、ユーロピウムの分配比は僅かに低下する。従って、ＴＰＥＮと共にジ（２、４、４−トリメチルフェニル）ジチオリン酸を添加した抽出液を用いた場合にも優れた分離効果を発揮することがわかる。
【００２４】
〔実施例６〕
２-エチルヘキシルアルコールにジ(2-エチルヘキシル)リン酸(D2EHPA)のみを溶解した抽出液(III)０.５mlを調製した。また、２-エチルヘキシルアルコールにD2EHPAとTPENとを２対１に混合溶解した抽出液(IV)０.５mlを調製した。さらに、０.１Ｍ硝酸アンモニウム、１mＭ硝酸ユーロピウム、トレーサ量(10-9M程度)のユーロピウム152、およびトレーサ量(10-9M程度)のアメリシウム241を含むｐＨ４程度の水溶液０.５mlを調製した。この水溶液と上記抽出液(III)、および上記水溶液と上記抽出液(IV)とをそれぞれマイクロチューブに入れて３０分間振蘯した後、有機相と水相とに分離し、各相に含まれるユーロピウム152とアメリシウム241の放射線を測定して各元素の分配比を求めた。その結果を図６(Ａ)(Ｂ)に示す。図６(Ａ)に示すように、Ｄ２ＥＨＰＡを単独に用いたものはユーロピウムとアメリシウムの分配比が接近しており、分離効果が低いが、Ｄ２ＥＨＰＡとＴＰＥＮを組み合わせた溶液を用いた図６(Ｂ)のものは、アメリシウムの分配比がユーロピウムのそれよりも格段に大きく、従って、有機溶媒として２-エチルヘキシルアルコールを用いた場合にも優れた分離効果を発揮することがわかる。
【００２５】
【発明の効果】
本発明によれば、ＴＰＥＮを用い、好ましくはＴＰＥＮとＤ２ＥＨＰＡ等の一般的な抽出剤とを組み合わせて用いることにより、高レベル廃液に含まれるアメリシウムやキュリウムなどのアクチノイド元素と希土類元素とを効率よく抽出分離することができる。
【図面の簡単な説明】
【図１】 Ｄ２ＥＨＰＡを単独に用いた抽出液と、Ｄ２ＥＨＰＡとＴＰＥＮとを併用した抽出液の効果を各々示したグラフ。
【図２】一連の希土類元素の分配比と、同条件で行ったアメリシウムの分配比を比較したグラフ。
【図３】 初期ｐＨに対するアメリシウムとユーロピウムの分配比を示すグラフ。
【図４】 抽出処理を一週間行ったときの分配比の変化を示すグラフ。
【図５】 ジ(2、4、4-トリメチルフェニル)ジチオリン酸を添加した抽出液を用いた場合のＴＰＥＮ濃度に対する分配比の変化を示すグラフ
【図６】 有機溶媒として２-エチルへキシルアルコールを用いた場合のＴＰＥＮの効果を示したグラフ。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for easily and stably separating rare earth elements (scandium, yttrium, and lanthanoids) and actinoid elements with a small amount of processing liquid.
[0002]
Various radioactive elements are contained in the high-level radioactive liquid waste generated after reprocessing spent nuclear fuel. In particular, since long-lived actinides are toxic for a long period of time, there is a need for a reliable separation method that can be separated from radioactive liquid waste and can be safely transmuted. The present invention is an essential technique for such a disposal method, and according to the processing technique of the present invention, a small amount of actinium elements such as americium and curium can be efficiently recovered from rare earth elements contained in large amounts in high-level waste liquid. Can do.
[0003]
[Prior art]
The following methods are conventionally known as methods for separating rare earth elements and actinoid elements.
(B) Method using D2EHPA and DTPA Trivalent using an extract containing di-2-ethylhexyl phosphate (D2EHPA) and diethylenetriamine N, N, N ', N ", N'"-5 acetic acid (DTPA) Trivalent actinoid elements can be extracted and separated from rare earth elements. However, since this method is highly dependent on the pH of the processing solution, the pH of the processing solution must be strictly adjusted, and the processing operation is troublesome because a buffering agent such as lactic acid is required.
[0004]
(B) Method using thiocyan ion and azide ion By using thiocyan ion and azide ion, the trivalent rare earth element and the trivalent actinoid element can be separated. However, this method has a problem that it is necessary to add a high-concentration salt of several moles, the amount of secondary waste is large, and the chemical stability is low.
[0005]
(C) Method using Cyanex Americium and Europium can be separated using di (2,4,4-trimethylphenyl) dithiophosphoric acid (CYANEX301: manufactured by CYTEC Canada). However, this method has a problem that the treatment solution (CYANEX301) needs to be purified to 99% or more, and has a low chemical stability with respect to an acidic solution.
[0006]
(D) Method using TPTZ Separation of americium and europium using tris [2,4,6- (2-pyridyl)] 1,3,5-triazine (TPTZ) together with dinonylnaphthalene sulfonic acid (HDNNS) However, since HDNNS is a surfactant, there is a problem that the separation between the organic phase and the aqueous phase is very poor.
[0007]
(E) Method using BTP A series of compounds called bistriazinylpyridine (BTP) (formal name: 2,6-di [5,6-alkyl-1,2,4-triazin-3-yl] pyridine) And has been proposed to separate americium and europium. However, since this compound has a very low chemical stability, it cannot be used for a long period of time, and there are very few solvents suitable for dissolution.
[0008]
[Problem to be Solved by the Invention]
The present invention solves the above-mentioned conventional problems in the method for separating rare earth elements and actinoid elements, and provides a technique for separating rare earth elements and actinoid elements efficiently, simply and stably with a small amount of processing liquid. is there.
[0009]
The present inventors previously examined the extraction effect on americium (Am) and europium (Eu) for the extract obtained by adding TPEN as an auxiliary agent to D2EHPA. When D2EHPA was used as the extractant, the concentration was extremely low. Even if only D2EHPA is present, the extraction ability of D2EHPA is sufficiently larger than the complexing ability of TPEN, and thus it was found that the influence of TPEN on the distribution ratio of Am and Eu was not observed. However, as a result of further investigation, it was found that in the extract using D2EHPA and TPEN in combination, the influence of TPEN appears under liquidity of pH 3 or higher, and the difference in the distribution ratio between Am and Eu increases. The present invention is based on this finding.
[0010]
[Means for solving the problems]
The present invention uses an extract containing N, N, N ′, N ″ -tetramethylpyridylethylenediamine (TPEN) and di-2-ethylhexyl-phosphate (D2EHPA) under a pH of 3-6 , The present invention relates to a separation method characterized by extracting and separating rare earth elements and actinoid elements.
[0011]
Further, the present invention, N, N, N ', N "- tetramethyl-pyridyl ethylenediamine (TPEN) di-2-ethylhexyl - and a phosphoric acid (D2EHPA), be used under humoral pH3~6 The present invention relates to an extraction and separation liquid of rare earth elements and actinoid elements.
[0012]
Hereinafter, the present invention will be specifically described based on embodiments.
The present invention uses (i) an extract containing N, N, N ′, N ″ -tetramethylpyridylethylenediamine (TPEN) and di-2-ethylhexyl-phosphate (D2EHPA), and has a pH of 3-6 . And (b) N, N, N ′, N ″ -tetramethylpyridylethylenediamine (TPEN) and di-2-ethylhexyl-phosphoric acid, characterized by extracting and separating rare earth elements and actinoid elements The present invention relates to an extraction / separation liquid for rare earth elements and actinoid elements, characterized in that it is used in a liquid state of pH 3 to 6 (D2EHPA).
[0013]
Since TPEN is chemically stable and can be easily synthesized in high purity, it does not need to be purified at the time of use, and a significant separation effect can be obtained with a small amount. Therefore, the generation of secondary waste can be suppressed. Further, by combining TPEN with various solvents, commercially available extractants, and the like, an effect excellent in solubility and phase separation can be obtained, and various separation conditions can be dealt with.
[0014]
As a combination with a solvent or another extractant, for example, a combination of TPEN and di-2-ethylhexyl-phosphate (D2EHPA) is preferable. Specifically, an extract obtained by dissolving 1 mol of TPEN in 2 mol of D2EHPA in an organic solvent such as alcohol may be used. By using an extract containing D2EHPA together with TPEN under a pH of 3 to 6 , a high distribution ratio of the actinide element to the rare earth element can be achieved, and an excellent separation effect can be obtained.
[0015]
As a reference example, an extract obtained by adding di (2,4,4-trimethylphenyl) dithiophosphoric acid together with TPEN to an organic solvent may be used. When this extract is used at a pH of 3 or more, the distribution ratio of americium generally increases with increasing TPEN concentration in the range of 1 to 10 molar concentration of TPEN, while the decomposition ratio of europium gradually increases. Since it decreases, an excellent separation effect can be obtained.
[0016]
As an organic solvent for dissolving TPEN, alcohol, nitrobenzene, or the like can be used. Note that TPEN dissolved in nitrobenzene can separate rare earth elements and actinoid elements by TPEN alone without using D2EHPA or the like.
[0017]
An extract in which di-2-ethylhexyl-phosphate (D2EHPA) is dissolved in an organic solvent together with TPEN, or an extract in which di (2,4,4-trimethylphenyl) dithiophosphate is dissolved in an organic solvent together with TPEN, or An extract obtained by dissolving TPEN in nitrobenzene is used at a pH of 3 or higher, and this extract is mixed with an aqueous solution containing a rare earth element and an actinoid element to transfer the actinoid element to the extract to separate it from the rare earth element. . In the region where the pH is lower than 3 (acid side), the distribution ratio of the actinide element and the rare earth element is close, but in the neutral side (region of pH 3 to 6 as shown in FIG. 3) , the distribution ratio of the actinoid element is Since it is maintained much higher than the distribution ratio of rare earth elements, an excellent separation effect can be obtained. In addition, since this pH adjustment will maintain a high distribution ratio if the initial pH of the said aqueous solution is adjusted to about 3 or more, it is not necessary to adjust pH more strictly than this. Therefore, pH adjustment is easy.
[0018]
If the said extract containing TPEN is used, as shown in an Example, the isolation | separation effect outstanding with respect to the actinide element can be acquired even with a small amount of processing liquid. Further, it is possible to maintain a high distribution coefficient by repeating the number of extractions and the number of days, and obtain a stable separation effect for a long period of time.
[0019]
【Example】
Hereinafter, the present invention will be specifically described by way of examples. The scope of the present invention is not limited by this example.
[Example 1]
0.5 ml of extract (I) in which only di (2-ethylhexyl) phosphoric acid (D2EHPA) was dissolved in 1-octanol was prepared. In addition, 0.5 ml of an extract (II) prepared by mixing and dissolving 2: 1 D2EHPA and TPEN in 1-octanol was prepared. Further, 0.5 ml of an aqueous solution having a pH of about 4 containing 0.1 M ammonium nitrate, 1 mM europium nitrate, tracer amount (about 10 -9 M) europium 152, and tracer amount (about 10 -9 M) americium 241 was prepared. The aqueous solution and the extract (I), and the aqueous solution and the extract (II) are placed in a microtube and shaken for 30 minutes, and then separated into an organic phase and an aqueous phase, which are contained in each phase. The radiation ratio of europium 152 and americium 241 was measured to determine the distribution ratio of each element (ratio of the amount transferred to the organic phase relative to the amount remaining in the aqueous phase). The results are shown in FIGS. 1 (A) and 1 (B). As shown in FIG. 1 (A), when D2EHPA is used alone, the distribution ratio of europium and americium is close and the separation effect is low, but FIG. 1 (B) using a solution combining D2EHPA and TPEN is used. ) Shows that the distribution ratio of americium is much larger than that of europium, and therefore an excellent separation effect can be obtained.
[0020]
[Example 2]
0.5 ml of an extract in which di (2-ethylhexyl) phosphoric acid (D2EHPA) and 1 mM TPEN were dissolved in 1-octanol was prepared. On the other hand, 0.5 ml of an aqueous solution having a pH of about 4 containing 0.14M ammonium nitrate and 20 ppm of various rare earth elements was prepared, and the aqueous solution and the extract were shaken for 30 minutes. And the concentration of each rare earth element contained in each phase was measured to determine the distribution ratio. The result is shown in FIG. As shown in the figure, the distribution ratio of americium is 22, whereas the distribution ratio of rare earth elements La to Gd is about 0.5 or less, and the difference in distribution ratio is large. Therefore, it can be seen that americium and rare earth elements can be effectively separated by using the above extract.
[0021]
Example 3
0.5 ml of an extract in which 2 mM di (2-ethylhexyl) phosphoric acid (D2EHPA) and 1 mM TPEN were dissolved in 1-octanol was prepared. On the other hand, ammonium nitrate 0.1 M, europium 152 weight tracer (about 10 -9 M), the amount of tracer a solution 0.5ml were prepared containing americium 241 (10-9 about M), and this aqueous solution and the extract After putting in a microtube and shaking for 30 minutes, it was separated into an organic phase and an aqueous phase, and the radiation of europium 152 and americium 241 contained in each phase was measured to obtain the distribution ratio of each element. At this time, the aqueous solution whose pH was adjusted to about 2 to 6 in advance was used, and the dependence of the initial pH on the distribution ratio was examined. The result is shown in FIG. As shown in the figure, in the range of pH 3 or higher, americium maintains a high distribution ratio with respect to europium. Therefore, for an aqueous solution containing these elements, if the initial pH is adjusted to about 3 or higher, It can be seen that an excellent separation effect can be obtained without requiring strict pH adjustment in a more neutral region. Therefore, no pH adjusting buffer is required.
[0022]
Example 4
Using the same aqueous solution containing europium 152 and americium 241 as in Example 3 and an extract containing D2EHPA and TPEN, these were placed in a microtube and shaken for 30 minutes, and then separated into an organic phase and an aqueous phase. The distribution ratio of each element was obtained by measuring the radiation of europium 152 and americium 241 contained in the phase. This operation was repeated for several days, and the stability of the distribution ratio with respect to the contact time was examined. The result is shown in FIG. As shown in the figure, it can be seen that the distribution ratio of americium is stable and does not depend on the contact time even after repeated contact.
[0023]
[Reference Example 5]
Prepare 0.5 ml of an extract containing 10 mM di (2,4,4-trimethylphenyl) dithiophosphoric acid (trade name: CYANEX 301) purified to a purity of 99.5% or more in 1-octanol and TPEN at each concentration. did. This extract, 0.1M ammonium nitrate, 1mM europium nitrate, tracer amount (about 10-9M) of europium 152 and tracer amount (about 10-9M) of americium 241 0.5ml in aqueous solution Mix and shake for 30 minutes. After shaking, the organic phase and the aqueous phase are separated for each sample solution, and the radiation ratios of europium 152 and americium 241 in each phase are measured to determine the distribution ratio, and the dependence of the TPEN concentration on the distribution ratio is examined. It was. In addition, the aqueous solution whose pH was adjusted to about 4 in advance was used. The result is shown in FIG. In this example, when the TPEN concentration is zero, the distribution ratio of americium and europium is almost equal, but as the TPEN concentration increases, the distribution ratio of americium increases, while the distribution ratio of europium slightly decreases. Therefore, it can be seen that an excellent separation effect is exhibited even when an extract obtained by adding di (2,4,4-trimethylphenyl) dithiophosphoric acid together with TPEN is used.
[0024]
Example 6
0.5 ml of extract (III) in which only di (2-ethylhexyl) phosphoric acid (D2EHPA) was dissolved in 2-ethylhexyl alcohol was prepared. In addition, 0.5 ml of an extract (IV) prepared by mixing and dissolving D2EHPA and TPEN in 2-ethylhexyl alcohol in a 2-to-1 ratio was prepared. Further, 0.5 ml of an aqueous solution having a pH of about 4 containing 0.1 M ammonium nitrate, 1 mM europium nitrate, tracer amount (about 10 -9 M) europium 152, and tracer amount (about 10 -9 M) americium 241 was prepared. The aqueous solution and the extract (III), and the aqueous solution and the extract (IV) are put in a microtube and shaken for 30 minutes, and then separated into an organic phase and an aqueous phase, which are contained in each phase. The radiation ratios of europium 152 and americium 241 were measured to determine the distribution ratio of each element. The results are shown in FIGS. 6 (A) and 6 (B). As shown in FIG. 6 (A), when D2EHPA is used alone, the distribution ratio of europium and americium is close and the separation effect is low, but FIG. 6 (B) using a solution combining D2EHPA and TPEN is used. It can be seen that the distribution ratio of americium is much larger than that of europium, and therefore, even when 2-ethylhexyl alcohol is used as the organic solvent, an excellent separation effect is exhibited.
[0025]
【The invention's effect】
According to the present invention, by using TPEN, preferably a combination of TPEN and a general extractant such as D2EHPA, actinide elements such as americium and curium and rare earth elements contained in the high-level waste liquid can be efficiently used. It can be extracted and separated.
[Brief description of the drawings]
FIG. 1 is a graph showing the effects of an extract using D2EHPA alone and an extract using D2EHPA and TPEN in combination.
FIG. 2 is a graph comparing the distribution ratio of a series of rare earth elements and the distribution ratio of americium performed under the same conditions.
FIG. 3 is a graph showing the distribution ratio of americium and europium with respect to the initial pH.
FIG. 4 is a graph showing a change in distribution ratio when extraction processing is performed for one week.
FIG. 5 is a graph showing the change in the distribution ratio with respect to the TPEN concentration when using an extract added with di (2,4,4-trimethylphenyl) dithiophosphoric acid. FIG. 6 shows 2-ethylhexyl alcohol as an organic solvent. The graph which showed the effect of TPEN at the time of using.
Claims (3)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002269233A JP4154453B2 (en) | 2002-09-13 | 2002-09-13 | Separation method of rare earth elements and actinoid elements and extract thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002269233A JP4154453B2 (en) | 2002-09-13 | 2002-09-13 | Separation method of rare earth elements and actinoid elements and extract thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2004108837A JP2004108837A (en) | 2004-04-08 |
| JP4154453B2 true JP4154453B2 (en) | 2008-09-24 |
Family
ID=32267216
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2002269233A Expired - Lifetime JP4154453B2 (en) | 2002-09-13 | 2002-09-13 | Separation method of rare earth elements and actinoid elements and extract thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4154453B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2459522B1 (en) * | 2009-07-30 | 2013-06-26 | Secretary, Department Of Atomic Energy | Dialkyldiaza-tetraalkyloctane diamide derivatives useful for the separation of trivalent actinides from lanthanides and process for the preparation thereof |
| FR2968014B1 (en) * | 2010-11-25 | 2012-12-28 | Commissariat Energie Atomique | PROCESS FOR SEPARATING AMERICIUM FROM OTHER METAL ELEMENTS PRESENT IN AN ACOUSTIC OR ORGANIC AQUEOUS PHASE AND APPLICATIONS THEREOF |
-
2002
- 2002-09-13 JP JP2002269233A patent/JP4154453B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JP2004108837A (en) | 2004-04-08 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US9051629B2 (en) | Process for separating americium from other metallic elements present in an acidic aqueous or organic phase | |
| EP3520117B1 (en) | Separation of metal ions by liquid-liquid extraction | |
| CN102549176B (en) | Increase in the separation factor between americium and curium and/or between lanthanides in a liquid-liquid extraction process | |
| JP4524394B2 (en) | Extraction method of americium and neodymium present in acidic solution | |
| JP6938813B1 (en) | A method for producing a gadolinium compound having a reduced content of radioactive elements, and a gadolinium compound. | |
| EP2496562A1 (en) | Process for the preparation of calcobutrol | |
| DK180858B1 (en) | Separation of actinium from process liquors | |
| JP4154453B2 (en) | Separation method of rare earth elements and actinoid elements and extract thereof | |
| JPH10115695A (en) | Method for selective separation of actinoids (iii) and lanthanoids (iii) | |
| US12226710B2 (en) | Chromatographic separation of metals using DOTA-based chelators | |
| US7754167B2 (en) | Method for separating trivalent americium from trivalent curium | |
| JP4117491B2 (en) | Method for back-extracting trivalent and tetravalent actinide ions in a separation process solvent into a highly concentrated nitric acid solution with N, N, N ', N'-tetraethyldiglycolamide | |
| JP4452837B2 (en) | Extraction separation method | |
| JP4036357B2 (en) | Modification of actinide extraction solvents containing tridentate ligands | |
| JP4124133B2 (en) | Method of extracting and separating Np (IV), Pu (III), Pu (IV), Am (III), and Cm (III) in a 1-6M nitric acid solution at once with an oxapentanediamine compound | |
| RU2343164C1 (en) | Method of metal isolation from solutions (versions) | |
| JP4568897B2 (en) | Method for selectively separating only trivalent actinoids from a solution containing trivalent actinoids and trivalent lanthanoids using 1,10-phenanthroline or an alkyl derivative thereof | |
| JP4315591B2 (en) | Method for separating trivalent actinides from at least trivalent lanthanides using (bis) aryl-dithiophosphinic acid as extractant and organophosphate as synergist | |
| JP5317256B2 (en) | Extraction agent and extraction / separation method, and N, N, N ′, N ″ -tetrakis (2-methylpyridyl) ethylenediamine derivative and method for producing the same | |
| JP6947008B2 (en) | Zirconium labeling method | |
| FR3154393A1 (en) | RARE EARTH COMPOSITION FROM LIQUID/LIQUID EXTRACTION OF SOLUTIONS FROM THE PROCESSING OF XENOTIME, MONAZITE, BASTNAESITE AND/OR IONIC CLAY ORES | |
| Handini et al. | The process of eliminating uranium and thorium in the deposition of rare Earth carbonates from xenotime alkaline roasting | |
| SEKINE et al. | Solvent extraction equilibria of some univalent metal ions with β-diketones in methylisobutylketone | |
| KR20260013874A (en) | Recovery method of high-purity uranium | |
| JPH077100B2 (en) | Method for selectively separating cesium ions from aqueous solution |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A821 Effective date: 20020918 |
|
| A711 | Notification of change in applicant |
Free format text: JAPANESE INTERMEDIATE CODE: A711 Effective date: 20040521 |
|
| A711 | Notification of change in applicant |
Free format text: JAPANESE INTERMEDIATE CODE: A712 Effective date: 20040521 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20050909 |
|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20050909 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A821 Effective date: 20050912 |
|
| A711 | Notification of change in applicant |
Free format text: JAPANESE INTERMEDIATE CODE: A712 Effective date: 20060228 |
|
| RD04 | Notification of resignation of power of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7424 Effective date: 20060303 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20070314 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20080129 |
|
| RD02 | Notification of acceptance of power of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7422 Effective date: 20080305 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20080327 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20080422 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20080520 |
|
| A711 | Notification of change in applicant |
Free format text: JAPANESE INTERMEDIATE CODE: A711 Effective date: 20080520 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110718 Year of fee payment: 3 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 4154453 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110718 Year of fee payment: 3 |
|
| S531 | Written request for registration of change of domicile |
Free format text: JAPANESE INTERMEDIATE CODE: R313531 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110718 Year of fee payment: 3 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120718 Year of fee payment: 4 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130718 Year of fee payment: 5 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| EXPY | Cancellation because of completion of term |