イオン液体における参照電極 －金属電析を実例に－2012/11/22 · イオン液体における参照電極 －金属電析を実例に－ 京都大学大学院工学研究科
マイクロ波と熱応答性イオン液体を用いた高レベル...
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マイクロ波と熱応答性イオン液体を用いた高レベル放射性廃液からの 白金族元素迅速抽出法に関する研究 Microwave-Assisted Homogeneous Liquid-Liquid Extraction of Platinum Group Elements from Nitric Acid Aqueous Solution to Thermomorphic [Hbet][Tf 2 N] Ionic Liquid Saki Ikeda, Takahiro Mori, Koichiro Takao, Yasuhisa Ikeda Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology Introduction Nuclear Fuel Cycle and vitrification Nuclear Fuel Cycle Enrichment Mining of Uranium Vitrification Storage (30~50years) Geological disposal Reprocessing 300 m high-level radioactive waste (HLW) ・・・Including Ru, Rh, Pd ：affect the vitrification process Separation of these metal species is necessary. There is no good method to separate them. Thermomorphic ionic liquid ; [Hbet][Tf 2 N] Microwave irradiation Ionic liquids are organic salts which are liquid at room temperature. Ionic liquids have unique properties; Thermal stability Non flammability Low vapor pressure [Hbet][Tf 2 N] consists of [Hbet] + and [Tf 2 N] - . Themomorphic ionic liquid ：Liquid-liquid equilibrium of [Hbet][Tf 2 N] and H 2 O has upper critical solution temperature (UCST). [Hbet][ Tf 2 N] is known as promising solvent for phase-transition extraction. ：Ru(III) and Rh(III) are not extracted efficiently from HLW, because they are inert species. Inductive heating Energy saving Rapid heating →extraction system using [Hbet][ Tf 2 N] can be heated rapidly. Complex formation reactions of inert-metal species such as Ir(III), Ru(III) should be efficiently accelerated. 20℃ 60℃ heat cool To examine the effectiveness of the microwave irradiation on extraction reactions of Ru(III) and Rh(III). Ionic liquids (Ils) Objective [Hbet][Tf 2 N] v Experimental - I Liquid-liquid extraction Experimental - II Microwave assisted extraction With increasing temperature, homogeneous phase is formed. Hence, fast reaction between the metal ion and the extractant can take place. N O OH [Hbet] + [Tf 2 N] - At low temperature, aqueous and IL phases are separated. E = 100×([M n+ ] ini – [M n+ ] aq ) / [M n+ ] ini D = ([M n+ ] ini – [M n+ ] aq ) / [M n+ ] aq v Results & Discussion - I : Liquid-liquid extraction v Results & Discussion - II : Microwave assisted extraction Single system Mixed system Extractability (E%) of Ru(III), Rh(III), and Pd(II) in the [Hbet][Tf 2 N]-0.3 M HNO 3 (aq) system. Left: single system, Right: mixed system. Mixed system: solution system containing Ru(III), Rh(III), and Pd(II). Single and mixed systems show similar extraction behavior. Extraction of Pd(II) attained equilibrium after shaking for1 h. Extraction of Ru(III) and Rh(III) did not reach equilibrium even after shaking for 52 h. Single system Single system Extractability (E%) of Ru(III), Rh(III), and Pd(II) vs. [HNO 3 ] in the [Hbet][Tf 2 N]-HNO 3 (aq) system. Shaking time: 1 h. Single system: solution system containing Ru(III), Rh(III), or Pd(II). With increasing [HNO 3 ], the extractability of each metal species decreases. Pd(II) at 0.3M [HNO 3 ] shows high extractability. Order of extractability at [HNO 3 ] = 0.3 M is Pd(II) > Rh(III) > Ru(III). Mixed system Extractability (E%) of Ru(III), Rh(III), and Pd(II) in microwave assisted extraction of the [Hbet][Tf 2 N]- 0.3 M HNO 3 (aq) system. Left: single system, Right: mixed system. Extraction equilibrium of three metal species is reached at 300 s in both systems. Logarithmic plots of D of Ru(III), Rh(III), and Pd(II) vs. [HNO 3 ] in the [Hbet][Tf 2 N]- HNO 3 (aq) system. Left: single system, Right: Mixed system. The D values were evaluated from the concentrations of metal species in aqueous phases after reaching the extraction equilibrium under microwave irradiation. Single system Mixed system The slops of log D-log [HNO 3 ] show negative values. These negative values suggest that the deprotonation of [Hbet] + contributes the extraction reactions and that the resulting bet species coordinate to Ru(III), Rh(III), and Pd(II). [Hbet] + → H + + (H 3 C) 3 N + -CH 2 COO - v v Conclusions Future Works Microwave irradiation largely accelerates the homogeneous liquid-liquid extraction reactions of Rh(III) and Ru(III) in the HNO 3 (aq)-[Hbet][Tf 2 N] system. Especially, Rh(III) is efficiently extracted by microwave irradiation method. Detail studies on extraction mechanism. Mutual separation of Ru(III), Rh(III), and Pd(II). Investigation of new ionic liquids. This dissociation can explain the fact that extractability of Ru(III), Rh(III), and Pd(II) decrease with increasing [HNO 3 ], because the increase in [HNO 3 ] depresses the deprotonation of [Hbet] + . J. Phys. Chem. Lett., 2013, 4 (10), pp 1659–1663 Nuclear power plant
Transcript of マイクロ波と熱応答性イオン液体を用いた高レベル...
マイクロ波と熱応答性イオン液体を用いた高レベル放射性廃液からの白金族元素迅速抽出法に関する研究
Microwave-Assisted Homogeneous Liquid-Liquid Extraction of Platinum Group Elements from Nitric Acid Aqueous Solution to Thermomorphic [Hbet][Tf2N] Ionic Liquid
Saki Ikeda, Takahiro Mori, Koichiro Takao, Yasuhisa Ikeda Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology
Introduction Nuclear Fuel Cycle and vitrification
Nuclear Fuel
Cycle
Enrichment
Mining of Uranium
Vitrification Storage (30~50years)
Geological disposal
Reprocessing
300 m
high-level radioactive waste (HLW)
・・・Including Ru, Rh, Pd
：affect the vitrification process Separation of these metal species is necessary. There is no good method to separate them.
Thermomorphic ionic liquid ; [Hbet][Tf2N] Microwave irradiation
Ionic liquids are organic salts which are liquid at room temperature. Ionic liquids have unique properties; Thermal stability Non flammability Low vapor pressure
[Hbet][Tf2N] consists of [Hbet]+ and [Tf2N]-. Themomorphic ionic liquid
：Liquid-liquid equilibrium of [Hbet][Tf2N] and H2O has upper critical solutiontemperature (UCST). [Hbet][ Tf2N] is known as promising solvent for phase-transition extraction.
：Ru(III) and Rh(III) are not extracted efficiently from HLW, because they are inert species.
Inductive heating Energy saving Rapid heating
→extraction system using[Hbet][ Tf2N] can beheated rapidly.
Complex formationreactions of inert-metalspecies such as Ir(III),Ru(III) should be efficientlyaccelerated.
20℃ 60℃
heat
cool
To examine the effectiveness of the microwave irradiation on extraction reactions of Ru(III) and Rh(III).
Ionic liquids (Ils)
Objective
[Hbet][Tf2N]
v
Experimental - I Liquid-liquid extraction
Experimental - II Microwave assisted extraction
With increasing temperature, homogeneous phase is formed. Hence, fast reaction between the metal ion and the extractant can take place.
N O
OH[Hbet]+ [Tf2N]-
At low temperature, aqueous and IL phases are separated.
E = 100×([Mn+]ini – [Mn+]aq) / [Mn+]ini D = ([Mn+]ini – [Mn+]aq) / [Mn+]aq
v
Results & Discussion - I : Liquid-liquid extraction
v
Results & Discussion - II : Microwave assisted extraction
Single system Mixed system
Extractability (E%) of Ru(III), Rh(III), and Pd(II) in the [Hbet][Tf2N]-0.3 M HNO3(aq) system. Left: single system, Right: mixed system. Mixed system: solution system containing Ru(III), Rh(III), and Pd(II).
Single and mixed systems show similar extraction behavior. Extraction of Pd(II) attained equilibrium after shaking for1 h. Extraction of Ru(III) and Rh(III) did not reach equilibrium even after shaking for 52 h.
Single system Single system
Extractability (E%) of Ru(III), Rh(III), and Pd(II) vs. [HNO3] in the [Hbet][Tf2N]-HNO3(aq) system. Shaking time: 1 h. Single system: solution system containing Ru(III), Rh(III), or Pd(II).
With increasing [HNO3], the extractabilityof each metal species decreases.
Pd(II) at 0.3M [HNO3] shows highextractability.
Order of extractability at [HNO3] = 0.3 Mis Pd(II) > Rh(III) > Ru(III).
Mixed system
Extractability (E%) of Ru(III), Rh(III), and Pd(II) in microwave assisted extraction of the [Hbet][Tf2N]-0.3 M HNO3(aq) system. Left: single system, Right: mixed system.
Extraction equilibrium of three metal species is reached at 300 s in both systems.
Logarithmic plots of D of Ru(III), Rh(III), and Pd(II) vs. [HNO3] in the [Hbet][Tf2N]- HNO3(aq) system. Left: single system, Right: Mixed system. The D values were evaluated from the concentrations of metal species in aqueous phases after reaching the extraction equilibrium under microwave irradiation.
Single system Mixed system
The slops of log D-log [HNO3] show negative values.These negative values suggest that the deprotonation of [Hbet]+ contributes the extraction reactions and that the resulting bet species coordinate to Ru(III), Rh(III), and Pd(II).
[Hbet]+ → H+ + (H3C)3N+-CH2COO-
v v
Conclusions Future Works
Microwave irradiation largely accelerates the homogeneous liquid-liquid extractionreactions of Rh(III) and Ru(III) in the HNO3(aq)-[Hbet][Tf2N] system.
Especially, Rh(III) is efficiently extracted by microwave irradiation method.
Detail studies on extraction mechanism.Mutual separation of Ru(III), Rh(III), and Pd(II). Investigation of new ionic liquids.
This dissociation can explain the fact that extractability of Ru(III), Rh(III), and Pd(II) decrease with increasing [HNO3], because the increase in [HNO3] depresses the deprotonation of [Hbet]+ .
J. Phys. Chem. Lett., 2013, 4 (10), pp 1659–1663
Nuclear power plant
