Deutsch-Französische Kooperation in der Entsorgungsforschung Forschungszentrum Jülich IEK-6

Transcription

1 Deutsch-Französische Kooperation in der Entsorgungsforschung Forschungszentrum Jülich IEK-6 Andreas Wilden German-French research for nuclear safety: Chemistry of the f-elements 1. Projektstatusgespräch zur BMBF-geförderten Nuklearen Sicherheitsforschung Karlsruhe, März 2013

2 FZJ-IEK-6 research collaborations In the field of nuclear waste disposal and innovative waste management strategies, IEK-6 has many long-lasting collaborations with French institutions through EU projects e.g. ACSEPT, ASGARD, SACSESS, and many others France often leading partner of the projects EU-projects often applied research, not so much fundamental the possibilities for individual sponsorship very limited, project oriented, esp. for young academics 2

3 IEK-6 involvement in BMBF funded project NUK012: Grundlegende Untersuchungen zur Entwicklung und Optimierung von Prozessen zur Abtrennung langlebiger Radionuklide (Partitioning) NUK020: Untersuchungen zum grundlegenden Verständnis der selektiven Komplexierung von f-elementen (f-kom) presentations M. Denecke, A. Bremer NUK021: Grundlegende Untersuchungen zur Immobilisierung langlebiger Radionuklide mittels Einbau in endlagerrelevante Keramiken presentations S. Neumeier, A. Wätjen More fundamental research Very good possibilities for individual sponsorship of young academics; direct collaboration with French institutions incl. travelling grants 3

4 Introduction to my collaborative work in the projects NUK012 and NUK020 Projects study the separation of the long-term radiotoxic actinides from waste solution through hydrometallurgical processes (liquid-liquid extraction) Improve understanding of the fundamental reasons for affinity, selectivity, and stability of certain extracting solvents on a molecular level Diluent plays a fundamental role in the performance of the extraction processes New diluents may significantly improve separation processes 4

5 Ionic liquids definition and properties Salt with a melting point below 100 C Combination of (org.) cation and anion + Non flammable + Non volatile + Resistant against radiolysis Often highly viscous expensive Nearly infinite number of combinations Synthesis of tailored Task-specific ionic liquids is possible 5

6 Classical ionic liquids Cations Anions e.g. [bumim] + (butyl-methyl-imidazolium) [Tf 2 N] - (bis-trifluoromethyl-sulfonyl amide) 6

7 Inverse HNO 3 dependency! [emim][tf 2 N] Surprising extraction in ionic liquids Extraction of lanthanides using TODGA in [C2mim][Tf 2 N] (closed symbols and solid line) or in isooctane (open symbols and broken line) [1] Different selectivity Lu > La > Eu in IL Lu > Eu > La in isooctane isooctane [1] Shimojo, K.; Kurahashi, K.; Naganawa, H. Dalton Trans. 2008, (37),

8 Typical extraction mechanism in common org. diluents 1) Solvation mechanism n M na ml MA L aq aq org n m org 2 UO 2NO 2TBP UO NO TBP 2,aq 3,aq org org 2) Ion exchange mechanism M nha ml MA L nh n aq org org n m org aq Neutral complexes in the org. phase! 8

9 Unconventional extraction mechanism in unconventional diluents In early studies on metal extraction into IL phases, also the formation of neutral complexes was assumed, following the solvation mechanism [2] 2 UO TBP 2 bumimtf N 2 2,aq 2 UO TBP Tf N 2bumim 2 2 org 2 2 org aq Further studies showed that this assumption was not in line with experimental results from UV-Vis studies and [HNO 3 ] dependency at low nitric acid concentration [3] Charged complexes in the IL phase! [2] Dietz, M. L.; Stepinski, D. C. Talanta 2008, 75 (2), [3] Billard, I.; Ouadi, A.; Jobin, E. et al. Solvent Extr. Ion Exch. 2011, 29 (4),

10 D Updated extraction mechanism 2 regimes of extraction Low HNO 3 concentration Regime I 100 UO 2 2+ /TBP/C n C 1 imtf 2 N UO bumim H ntbp 2 2,aq org org org 2 UO 2 TBP Haq bumim n org aq 10 C 5 C 4 C 4 1 High HNO 3 concentration Regime II UO 3NO mtbp Tf N 2 2,aq 3,aq org 2 org UO 2 NO3 TBP Tf2N 3 m org aq [3] Billard, I.; Ouadi, A.; Jobin, E. et al. Solvent Extr. Ion Exch. 2011, 29 (4), C 8 0,1 C 10 0,01 0,001 0,01 0, [HNO 3 ] aq,init (M) Boomerang -shape curve [3] 10

11 My work at CNRS Strasbourg (4 weeks) with Isabelle Billard Solubility tests of [bumim][tf 2 N] in org. diluents Solubility tests of extractants in [bumim][tf 2 N] UV-Vis studies (protonation of ligands) Liquid-liquid extraction using extractants dissolved in [bumim][tf 2 N] Modelling BCDTP Bis(4-chlorophenyl)- dithiophosphinic acid [bumim][tf 2 N] [3-butyl-1-methyl-1H-imidazolium] [bis((trifluoromethyl)sulfonyl)amide] CyMe 4 BTPhen 2,9-bis(5,5,8,8-tetramethyl-5,6,7,8- tetrahydrobenzo[e][1,2,4]triazin-3-yl)-1,10- phenanthroline 11

12 Modelling/Fitting of the extraction results I Extraction is a function of Chemical complex formation constant (mass action law) AmL x,org Am(NO 3 ) x,aq (Free) Ligand concentration Protonation of the Ligand? HNO 3 concentrations (aq+org) H + / NO 3 - / HNO 3 -dissociation [bumim + ] aq concentration [Tf 2 N - ] aq concentration H 2 O concentration (org) tabulated UV-Vis Titration / table NMR NMR Karl-Fischer 12

13 UV-Vis studies No observable change in the UV-Vis spectra (protonation) of BCDTP or CyMe 4 BTPhen in [bumim][tf 2 N] CyMe 4 BTPhen was studied in methanol instead CyMe 4 BTPhen 13

14 Extraction results BCDTP Am/Eu tracer Extraction into [bumim][tf 2 N] Without synergist No extraction! Probably a synergist is required 14

15 Extraction results CyMe 4 BTPhen Am/Eu tracer Extraction into [bumim][tf 2 N] Boomerang shape curve SF up to 250 At 0.01 mol/l HNO 3 quantitative extraction Inverse HNO 3 dependency! 15

16 Modelling/Fitting of the extraction results II First rough estimation model Estimated complexation constants Only one mechanism tested Good Am fit in region II Not so well fit in region I Activity coefficients of most species unknown SIT: most species unknown More exp. data is needed Eu fit generally not good Distribution ratios quite low 16

17 % Pu Further collaboration with Isabelle Billard and Michel Meyer CNRS Strasbourg: Isabelle Billard Extraction experiments Modelling/Fitting of experimental data Improvement of the model Determination of the extraction mechanism CNRS/Université de Bourgogne Dijon: Michel Meyer Determination of activity coefficients for SIT Aqueous complexation of actinides, but also important fission and corrosion products with partitioning-relevant ligands Pu(L) [Pu(L) 2 H] 3- [Pu(L) 2 H 2 ] 2- Pu(OH) 4(am) [Pu(L)(OH)] - [Pu(L) 2 ] p[h] 17

18 Conclusions / Outlook Ionic liquids provide unusual properties Enhanced safety Surprising extraction results Different mechanisms Interesting preliminary results were obtained Important funding through BMBF Funding of individuals and travelling grant German-French collaboration in the field of nuclear waste disposal is very important! France leading nation in nuclear application in Europe Direct neighbour of Germany and short distances Great knowledge and expertise of French partners 18

19 Acknowledgements CNRS Strasbourg Isabelle Billard Ali Ouadi Michal Sypula Olga Klimchuk Sylvia Georg Valerie Mazan CNRS / Université de Bourgogne Dijon Michel Meyer FZJ-IEK-6 Giuseppe Modolo Dirk Bosbach 02NUK012E 02NUK020E 19

20 Thank you for your kind attention