1. Atelier PARIS Extraction, ICSM, 10-11 décembre 2009 Study of DTPA and malonic acid extraction system for Ln(III)/An(III) separation Irena Špendlíková, Petr DISTLER CTU Prague, Czech Republic Manuel Miguirditchian, Fabien Burdet CEA Marcoule, France

2. ACSEPT semestrial meeting Manchester, april 4-7 2011 2 Extraction system Results important for understanding the chemistry of the process for modelling and simulating the process  Selective stripping of actinides (Am, Cm) from lanthanides  Change of the stripping solution from HEDTA-citric acid to DTPA-malonic acid  Easier degradation of DTPA and malonic

3. ACSEPT semestrial meeting Manchester, april 4-7 2011 3 Content Experimental procedure Stability constants with DTPA Impact of malonic acid pH dependence Temperature dependence Kinetics experiments –Inactive / active experiments –Influence of saturation –Influence of pH –Influence of temperature Conclusions

4. ACSEPT semestrial meeting Manchester, april 4-7 2011 4 Experimental Procedure  Preequilibration of organic phase (0.3M HDEHP-0.6M DMDOHEMA/TPH)  with malonic acid at different pH  Loading of organic phase  with tracers ( 241 Am, 152 Eu, 139 Ce)  or/and other cations (La, Ce, Nd, Eu, Y, Pd, Zr, Fe)  Stripping experiments with DTPA-malonic acid solutions  15 minutes mechanic shaking, thermostated, centrifuged  Organic and aqueous samples measured by gamma spectrometry or ICP- AES

5. ACSEPT semestrial meeting Manchester, april 4-7 2011 5 DTPA Dependence Extracted complexes: DTPA : Eu, Ce, Am = 1:1 Aq: 10 -6 M – 0.025 M DTPA at pH 2 Org: 0.3 M HDEHP, 0.6 M DMDOHEMA in TPH

6. ACSEPT semestrial meeting Manchester, april 4-7 2011 6 DTPA Stability constants ElementLog β(app) Am 3+ 23.45 Eu 3+ 22.93 Ce 3+ 21.65 pK 1 1.8 pK 2 2.55 pK 3 4.31 pK 4 8.54 pK 5 10.51 Acidity constants of DTPA Aq: 10 -6 M – 0.025 M DTPA at pH 2 Org: 0.3 M HDEHP, 0.6 M DMDOHEMA in TPH β app includes β MDTPA and β MHDTPA

7. ACSEPT semestrial meeting Manchester, april 4-7 2011 7 Impact of malonic acid no complexation with malonic acid => no ternary complex with DTPA just used as a buffer decrease in D values NH 2 OH as complexing agent ? => include in calculations Aq: 10mM DTPA, 0-1M malonic acid at pH 2 Org: 0.3 M HDEHP, 0.6 M DMDOHEMA in TPH NH 2 OH NaOH

8. ACSEPT semestrial meeting Manchester, april 4-7 2011 8 pH dependence  Org: 0.3 M HDEHP-0.6 M DMDOHEMA in TPH preequilibrated and loaded with 241 Am, 139 Ce, 152 Eu  Aq: 0.01M DTPA, 0.3M malonic acid at different pH adjusted by NH 2 OH or NaOH Stronger impact on pH with NH 2 OH  Power 9 compare to power 4

9. ACSEPT semestrial meeting Manchester, april 4-7 2011 9 pH dependence  1H + exchanged with NaOH : no impact of the base  2H + exchanged with NH 2 OH : impact of the base in the stripping  Complexation of NH 2 OH after deprotonation ? Ternary complex Am(DTPA)(NH 2 OH) 2- ?  Extraction of NH 3 OH + by HDEHP: impact of saturation in organic phase

10. ACSEPT semestrial meeting Manchester, april 4-7 2011 10 Impact of pH and the base on the selectivity  No impact of the base on the separation factors 

11. ACSEPT semestrial meeting Manchester, april 4-7 2011 11 Temperature dependence ΔH [kJ/mol] 2.00 NH 2 OH2.50 NH 2 OH2.50 NaOH Ce-34.0±0.8-33.3±1.0-37.8±1.8 Eu-13.3±0.8-7.2±1.1-13.1±1.5 Am-27.2±0.6-20.5±0.2-26.6±0.7 ΔS [J/mol] 2.00 NH 2 OH2.50 NH 2 OH2.50 NaOH Ce78.9±2.886.3±3.197.4±5.9 Eu25.2±2.816.8±3.732.5±4.8 Am96.1±2.085.7±0.6102.4±2.2 0.01M DTPA – 0.3M malonic acid pH 2-2.5 (NH 2 OH or NaOH) - 5°-55°C van’t Hoff method

12. ACSEPT semestrial meeting Manchester, april 4-7 2011 12 Stripping Kinetics Element[mmo/l] Ce3.8 Eu3.5 Fe12.6 Nd5.8 Pd0.4 Y4.7 Zr9.3 Total39.9 Initial concentrations of cations in loaded organic phase Stripping of the loading organic phase with 0.01M DTPA – 0.3M malonic acid at different pH (2.0 ; 2.5 and 3.0) at different temperature (25, 35, 45°C) in FOC (and one experiment in FAC) spiked with 241 Am, 139 Ce and 152 Eu with macroconcentrations of cations or with tracers only

13. ACSEPT semestrial meeting Manchester, april 4-7 2011 13 Stripping Kinetics  Slow kinetics of stripping of Fe(III), Pd(II) and Zr(IV)  Relatively fast for Am and Eu  Good agreement between inactive and active experiments 0.01M DTPA – 0.3M malonic acid pH 2.5 (NH 2 OH) - 25°C

14. ACSEPT semestrial meeting Manchester, april 4-7 2011 14 Stripping Kinetics 0.01M DTPA – 0.3M malonic acid pHtemperature at pH 2.03, 2.48 and 2.84 at 25°Cat pH 2.46 (25°C), 2.46 (35°C), 2,47 (45°C)

15. ACSEPT semestrial meeting Manchester, april 4-7 2011 15 Stripping Kinetics 0.01M DTPA – 0.3M malonic acid – pH 2.8 (NH 2 OH) – 25°C no huge difference at 30 s FOC seems to be quicker FOC - fonctionement organique continous - dispersed aqueous phase in the organic one

16. ACSEPT semestrial meeting Manchester, april 4-7 2011 16 Conclusions and outlooks No ternary complex observed between DTPA and malonic acid –Different from HEDTA-citric acid No influence of malonic acid on D-values –Different from citric acid and lactic acid (Talspeak system) Strong influence of pH on D-values (with NH 2 OH in particular) Influence of NH 2 OH on the stripping –Formation of ternary complex Am(DTPA)(NH2OH) or extraction of NH 2 OH + by HDEHP Exothermic ethalpies of extraction Stripping kinetics of Am, Ln fast compared to Zr, Fe and Pd Strong influence of pH on the stripping kinetics => Results will be used for modelling of the process and for better understanding of its chemistry

17. ACSEPT semestrial meeting Manchester, april 4-7 2011 17