Studies on Separation of Actinides And Lanthanides by Extraction Chromatography Using 2,6-BisTriazinyl Pyridine

Transcription

1 Studies on Separation of Actinides And Lanthanides by Extraction Chromatography Using 2,6-BisTriazinyl Pyridine P. Deepika, K. N. Sabharwal, T. G. Srinivasan and P. R. Vasudeva Rao Fuel Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, India

2 OECD 2008, Japan 2

3 Availability/Capacity Factor (%) -----> Stage I PHWRs 12- Operating 6 - Under construction Several others planned Scaling to 700 MWe Gestation period being reduced POWER POTENTIAL 10,000 MWe LWRs 2 BWRs Operating 2 VVERs under construction THREE STAGE NUCLEAR POWER PROGRAM Stage - II Fast Breeder Reactors 40 MWth FBTR - Operating since 1985 Technology Objectives realised 500 MWe PFBR- Under Construction POWER POTENTIAL 530,000 MWe DAE Presentation on Stage - III Thorium Based Reactors 30 kwth KAMINI- Operating 300 MWe AHWR- Under Development POWER POTENTIAL IS VERY LARGE Availability of ADS can enable early introduction of Thorium on a large scale OECD 2008, Japan 3

4 Fast Breeder Test Reactor Kalpakkam OECD 2008, Japan 4

5 Radiochemistry Laboratory OECD 2008, Japan 5

6 Hot Cells OECD 2008, Japan 6

7 H The Chemist's Playground Minor actinides He Li Be Na Mg B C N O F Ne Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba (Ln) Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra (An) Rf Db Sg Bh Hs Mt Minor Actinides Man-made Radioactive Elements Naturally Radioactive Elements OECD 2008, Japan 7

8 Separation of MINOR actinides by various techniques DIDPA SASME HDEHP CYANEX 301 Minor Actinides TRUEX TPTZ TALSPEAK TRPO OECD 2008, Japan 8

9 Extractants used in our Laboratory for Co extraction of lanthanides and actinides Truex process ---- CMPO Solvent Extraction Diamides DMDBMA Solvent Extraction [Dimethyl Dibutyl Malonamide] TEHDGA --- Tetraethyl Hexyl Diglycoamide -- Solvent Extraction DMDOHEMA ---- Solvent Extraction [DimethylDioctylHexylEthoxyMAlonamide] OECD 2008, Japan 9

10 Other Techniques Extraction Chromatography Room Temperature Ionic Liquids Supercritical Fluid Extraction High Performance Liquid Chromatography OECD 2008, Japan 10

11 Actinide Lanthanide Separation Bis Triazinyl Pyridine (BTP) OECD 2008, Japan 11

12 OECD 2008, Japan 12

13 Outline Introduction Lanthanide-Actinide Separation. Bis Triazinyl Pyridines (BTPs). Advantages of Extraction Chromatography over Solvent Extraction. Experimental Work Synthesis of 2,6-bis(5,6-dipropyl-1,2,4-triazin-3- yl)pyridine. Preparation of the Extraction Resin. Extraction Studies of Am (III) and trivalent lanthanides by XAD-7 impregnated with 2,6- bis(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine. Conclusions OECD 2008, Japan 13

14 Introduction Lanthanide Actinide Separation Need Partitioning and Transmutation ( to reduce longterm radiological risks to the environment by transmutation of the minor actinides). Difficulty Lanthanides and actinides have similar chemical properties due to similar ionic radii. OECD 2008, Japan 14

15 Bis Triazinyl Pyridines (BTPs) First reported in 1999 by Kolarik, Mullich and Gassner that 2,6-di(5,6-dialkyl-1,2,4-triazin-3-yl)pyridines extract and separate Am(III) and Eu(III) very efficiently as nitrates. (Solvent Extraction and Ion Exchange, 17(1), 23-22, 1999) OECD 2008, Japan 15

16 Limitations of solvent extraction Third Phase formation, Need for phase-modifiers, Disposal of large volumes of extractants and diluents, Tedious multi-stage extraction procedures. Advantages of Extraction Chromatography No third phase formation, No need for a modifier, Reusability of the synthesized resin, Simple and compact equipment, Minimal loss of organic solvent. OECD 2008, Japan 16

17 Experimental Work Synthesis of 2,6-bis(5,6-dipropyl-1,2,4-triazine-3-yl)-pyridine H 2 H 2 N N C N N C N NH 2 NH 2 2,6-pyridine dicarboxam ide d ih yd ra zo n e + O O O ctane-4,5-dione N N N N N N N 2,6-bis(5,6-dipropyl-1,2,4-triazine-3-yl)pyridine OECD 2008, Japan 17

18 Preparation of the Extraction Resin Resin Impregnation XAD-7 particles Washing Air-drying (Methanol, Acetone) Extractant: npr-btp Diluent: dichloromethane Impregnation in rotary evaporator (298K, 2h) Extraction resin (npr-btp/xad-7) Air-drying Removing Diluent (323K) OECD 2008, Japan 18

19 Extraction Studies of Am (III) and trivalent lanthanides by XAD-7 impregnated with 2,6- bis(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine OECD 2008, Japan 19

20 K d Tim e, hr Figure : Kinetics of the uptake of Am (III) by npr-btp/xad-7 resin (0.25g npr- BTP/XAD-7, 0.1M HNO 3,2MNH 4 NO 3, 303K) Distribution coefficient (K d ) values increased with increasing time of equilibration and equilibrium is reached in 24 hours. For K d measurements, we have equilibrated for 3 hours. OECD 2008, Japan 20

21 W ithout NH 4 NO 3 W ith N H 4 NO 3 K d [H N O 3 ], M Figure: Effect of nitric acid concentration on the uptake of Am(III) by npr-btp/xad-7 resin with and without 2M NH4NO3 (0.25g npr-btp/xad-7, 303K, 3h). K d values for the extraction of Am(III) from nitric acid with ammonium nitrate are significantly higher. The increase of Am(III) adsorption with increasing nitrate concentration can be explained by the following adsorption equilibrium represented by Equation (1), M NO n(npr-btp) = M(NO 3 ) 3 (npr-btp) n (1) OECD 2008, Japan 21

22 A m (III) La(III) C e (III) N d (III) E u (III) G d (III) K d 500 K d [H N O 3 ], M [HNO 3 ], M Figure : Effect of nitric acid concentration on the uptake of Am(III) and lanthanides by npr-btp/xad-7 resin (0.25g npr-btp/xad-7, 2 M NH 4 NO 3, 303K, 3h) The lanthanides are not extracted by the resin at any acidity. K d value for the extraction of Am(III) is maximum at 0.1M nitric acid in the presence of ammonium nitrate. OECD 2008, Japan 22

23 A m (III) La(III) Gd(III) N d (III) C e (III) E u (III) K d 400 K d [N H 4 NO 3 ], M [N H 4 NO 3 ], M Figure : Effect of nitrate concentration on the uptake of Am(III) and Lanthanides by npr-btp/xad-7 resin (0.25g npr-btp/xad-7, 0.1M HNO 3, 303K, 3h) The distribution coefficient (K d ) value of Am (III) increases with increase in NH 4 NO 3 concentration, which can be explained by equation (1), M NO n(npr-btp) = M(NO 3 ) 3 (npr-btp) n (1) OECD 2008, Japan 23

24 [NH 4 NO 3 ] M Separation Factor (K d Am / K d Ln) La Ce Nd Eu Gd Table: Separation Factors for Americium-Lanthanide Separations ( 0.25g npr- BTP/XAD-7, 0.1M HNO3, 303K, 3h) OECD 2008, Japan 24

25 E u (III) Am(III) C/C V o lu m e, m L Figure : Loading of Am (III) and Eu (III) on to a column of npr-btp/xad-7 resin. Europium was not retained in the column and up to 99.4% of it was recovered at the loading stage itself. Up to 90% of the Am was retained in the column. OECD 2008, Japan 25

26 6 Am (III) elution with 0.3M DTPA 5 4 C/Co V o lu m e, m L Figure : Elution of Am (III) from npr-btp/xad-7 column with 0.3M DTPA. Loaded Am(III) was recovered by passing 0.3 M DTPA solution (ph=4.0). 60% of Am was recovered within the first three column volumes. Further tailing was observed. OECD 2008, Japan 26

27 Conclusions - npr-btp impregnated XAD-7 resin displayed high selectivity for americium and good separation-factors for the separation of other lanthanides from the same. Column runs for the separation of americium from europium gave good results with 99.4% Europium being removed in the loading stage itself. The elution of Am from the column using DTPA was found to be 60% and efforts are on to improve the same. OECD 2008, Japan 27

28 Thank You.. OECD 2008, Japan 28