Investigation of mixed N, O-donor dipicolinamide derivative ligands for use in nuclear fuel ...

188 Pages·2013·2.88 MB·English

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AN ABSTRACT OF THE DISSERTATION OF

Joseph Lapka for the degree of Doctor of Philosophy in Chemistry presented on
December 4, 2013.

Title: Investigation of Mixed N,O-Donor Dipicolinamide Derivative Ligands for Use in
Nuclear Fuel Separations

Abstract approved: ______________________________________________________
Alena Paulenova

In this work, three isomeric forms of N, N’-diethyl, N, N’-ditolyldipicolinamide
(EtTDPA) were synthesized. The elements thorium through americium, which make up a
significant portion of the actinides in used nuclear fuel (with the exception of curium),
and two fission products, molybdenum and technetium, were tested for their ability to be
extracted by EtTDPA into a polar fluorinated diluent from nitric acid solutions at varying
concentrations of both nitric acid and organic ligand. These ligands were then further
analyzed for their stability when subject to the harsh conditions inflicted during used fuel
reprocessing. Degradation products were determined and the effect of their presence on
the extraction and separation of the actinide and lanthanide elements was investigated.
Finally, thermodynamics of the complexation between EtTDPA and neodymium were
investigated by spectroscopic, calorimetric, and solvent extraction methods. The data
presented here will hopefully be used in the future ligand design and implementation in
solvent extraction systems for the reprocessing of used nuclear fuel.
©Copyright by Joseph Lapka
December 4, 2013
All Rights Reserved
Investigation of Mixed N,O-Donor Dipicolinamide Derivative Ligands for Use in
Nuclear Fuel Separations

by
Joseph Lapka

A DISSERTATION

submitted to

Oregon State University

in partial fulfillment of
the requirements for the
degree of

Doctor of Philosophy

Presented December 4, 2013
Commencement June 2014
Doctor of Philosophy dissertation of Joseph Lapka presented on December 4, 2013

APPROVED:

Major Professor, representing Chemistry

Chair of the Department of Chemistry

Dean of the Graduate School

I understand that my dissertation will become part of the permanent collection of Oregon
State University libraries. My signature below authorizes release of my dissertation to
any reader upon request.

Joseph Lapka, Author
ACKNOWLEDGEMENTS

I would like to thank my advisor Dr. Alena Paulenova for giving me the opportunity to
perform the research presented here as well as assisting me in opening new doors within
the radiochemical community by allowing me to attend conferences around the world.

Special thanks are also needed for Dr. Mikhail Alyapyshev who, as a visiting graduate
student at OSU from Russia, was my initial mentor in the laboratory and several aspects
of this project.

Thank you to Jeff Moore and Christine Pastorek for their help in performing and
arranging mass-spectrometry experiments.

Thank you to Dr. Peter Zalupski for instructing me at Idaho National Lab for three weeks
on the complexities of isothermal titration calorimetry.

Thank you to our health physicists Scott and Jim for helping undo my accidents.

Finally, I was very lucky to have friends as lab mates to offer guidance and fun times
both in and out of the lab. Thank you Alex, Brent, Brian, Emily, Martin, Peter, and
Vanessa.
TABLE OF CONTENTS
Page
1. INTRODUCTION ....................................................................................................... 2
2. BACKGROUND AND LITERATURE REVIEW ..................................................... 6
2.1. Composition of Used Nuclear Fuel .......................................................................6
2.2. Hard-Soft Acid-Base Theory ................................................................................9
2.3. f-Element Chemistry ...........................................................................................12
2.3.1. Lanthanides ................................................................................................. 12
2.3.2. Actinides ..................................................................................................... 15
2.3.3. Separation of the Actinides and Lanthanides .............................................. 18
2.4. Solvent Extraction ...............................................................................................20
2.4.1. Neutral Solvate Ligands .............................................................................. 22
2.4.2. Ion Exchange Ligands................................................................................. 23
2.5. Reprocessing of Used Nuclear Fuel ....................................................................25
2.5.1. PUREX ....................................................................................................... 25
2.5.2. CCD/PEG .................................................................................................... 27
2.5.3. TRUEX ....................................................................................................... 29
2.5.4. TALSPEAK ................................................................................................ 30
2.5.5. UNEX ......................................................................................................... 33
2.6. “CHON” Extractants ...........................................................................................36
2.6.1. Amides ........................................................................................................ 36
2.6.2. N-Donor Extractants ................................................................................... 37
2.6.3. Mixed N, O-Donor Ligands ........................................................................ 39
TABLE OF CONTENTS (Continued)
Page
2.7. Chemical Equilibria ............................................................................................41
2.7.1. Equilibrium and Stability Constants ........................................................... 41
2.7.2. Stability Constant Determination ................................................................ 45
3. METHODS ................................................................................................................ 48
3.1. Synthesis of EtTDPA Isomers ............................................................................48
3.2. Solvent Extraction ...............................................................................................49
3.2.1. Chemicals .................................................................................................... 49
3.2.2. Analysis of Distribution Ratios ................................................................... 51
3.3. Degradation of EtTDPA ......................................................................................53
3.3.1. Sample Preparation ..................................................................................... 53
3.3.2. Analysis of Samples .................................................................................... 54
3.4. Determination of Thermodynamic Dynamic Constants .....................................55
3.4.1. Spectrophotometry ...................................................................................... 55
3.4.2. Calorimetry ................................................................................................. 56
4. EXTRACTION OF ACTINIDES AND SELECT FISSION PRODUCTS .............. 58
4.1. Molybdenum(VI) ................................................................................................58
4.2. Technetium(VII) .................................................................................................63
4.3. Uranium (VI) .......................................................................................................67
4.4. Neptunium(V) .....................................................................................................74
4.5. Protactinium(V) ..................................................................................................82
4.6. Thorium(IV) ........................................................................................................86
4.7. Plutonium(IV) .....................................................................................................89
TABLE OF CONTENTS (Continued)
Page
4.8. Non-Ideal Extraction Behavior ...........................................................................93
5. DEGRADATION OF ETTDPA AND ITS EFFECT ON EXTRACTION
CAPABILITY ........................................................................................................... 98
5.1. Radiolysis ............................................................................................................98
5.2. Hydrolysis .........................................................................................................104
5.3. Infrared Spectra of Organic Phase ....................................................................106
5.4. Determination of Radiolytic Products by Gas Chromatography-Mass
Spectroscopy .....................................................................................................107
5.4.1. EtTDPA in FS-13 ...................................................................................... 108
5.4.2. Hydrolysis of non-irradiated EtTDPA ...................................................... 110
5.4.3. Radiolysis of water contacted EtTDPA .................................................... 112
5.4.4. Radiolysis of EtTDPA Saturated with Nitric Acid ................................... 116
5.5. Thermal Stability ...............................................................................................121
5.6. Effects on Extraction of Americium and Europium .........................................122
5.6.1. Radioylsis .................................................................................................. 122
5.6.2. Hydrolysis ................................................................................................. 126
6. THERMODYNAMICS OF COMPLEXATION OF METALS BY EtTDPA ....... 135
6.1. Spectrophotometric Titrations ...........................................................................137
6.2. Calorimetric Titrations ......................................................................................144
6.3. Thermodynamics of Americium and Europium Extraction ..............................149
7. CONCLUSIONS ..................................................................................................... 154
8. REFERENCES ........................................................................................................ 157
LIST OF FIGURES (Continued)
Figure: Page

Figure 2.1: Masses of elements per initial heavy metal tons after 10 years cooling, PWR
(adapted from Choppin, G. R.; Liljenzin, J.; Rydberg, J.; Radiochemistry and Nuclear
Chemistry, 3rd Ed.) ............................................................................................................. 6
Figure 2.2: Heat output for LWR fuel (adapted from Choppin, G. R.; Liljenzin, J.;
Rydberg, J.; Radiochemistry and Nuclear Chemistry, 3rd Ed.) ......................................... 8
Figure 2.3: Structure of N, N’-tetraoctyldiglycolamide (TODGA) .................................. 22
Figure 2.4: Tributyl phosphate (TBP) ............................................................................... 26
Figure 2.5: Trifluoromethylphenyl sulfone (FS-13, top left), polyethylene glycol (PEG,
bottom left), and chlorinated cobalt dicarbollide (CCD, right) ........................................ 28
Figure 2.6: Carbamoylphosphine oxide (CMPO) ............................................................. 29
Figure 2.7: Di-(2-ethylhexyl)phosphoric acid (HDEHP) ................................................. 31
Figure 2.8: Diethylenetriaminepentaacetic (DTPA) ......................................................... 33
Figure 2.9: UREX+ multi-stage partitioning flowsheet of irradiated nuclear fuel ........... 34
Figure 2.10: UNEX separation concept ............................................................................ 35
Figure 2.11: BTP (left) and BTBP (right) heterocyclic N-donor ligands ......................... 38
Figure 2.12: Isomers of EtTDPA ortho (top), meta (middle), para (bottom) ................... 40
Figure 3.1: Synthesis of Et(p)TDPA ................................................................................. 48
Figure 3.2: Arsenazo(III) complexant dye ........................................................................ 52
Figure 4.1: D(Mo) as a function of nitric acid activity with 0.2 M EtTDPA in FS-13 .... 60
Figure 4.2: D(Mo) as a function of EtTDPA concentration at 3 M HNO in FS-13 ........ 61
3
Figure 4.3: D(Mo) at constant HNO and added LiNO with 0.2 M Et(p)TDPA ............ 62
3 3
Figure 4.4: Comparison of D(Mo) by Et(p)TDPA between HCl and HNO aqueous
3
phases ................................................................................................................................ 63
Figure 4.5: D(Tc) as a function of acid activity with 0.2 M EtTDPA in FS-13 ............... 65
Figure 4.6: D(Tc) at constant HNO and added LiNO with 0.2 M Et(p)TDPA in FS-13 66
3 3
Figure 4.7: D(Tc) from 3 M HNO with 0.05-0.20 M EtTDPA in FS-13 ........................ 67
3
Figure 4.8: Uranium extraction from 3 M HNO as a function of EtTDPA concentration
3
........................................................................................................................................... 69
Figure 4.9: Uranium extraction with 0.2 M EtTDPA from nitric acid as a function of
nitrate activity ................................................................................................................... 70
LIST OF FIGURES (Continued)
Figure: ...................................................................................................................... Page
Figure 4.10: Uranium extraction with 0.2 M EtTDPA from nitric acid and lithium nitrate
as a function of nitrate activity.......................................................................................... 71
Figure 4.11: Infrared Spectra of 0.2 M Et(p)TDPA in FS-13 a. before saturation, b.
saturation with 2 M HNO and 1 M LiNO , c. 2 M HNO and 4 M LiNO ..................... 73
3 3 3 3
Figure 4.12: Infrared spectra of organic phase before and after UO 2+ extraction with
2
Et(p)TDPA ........................................................................................................................ 74
Figure 4.13: Near-IR spectra of Np solution before and after contact with Et(p)TDPA .. 77
Figure 4.14: Distribution of Np(V) from nitric acid with 0.2 M EtTDPA ....................... 78
Figure 4.15: Extraction of Np(V) by variation of Et(o)TDPA concentration from various
nitric acid concentrations .................................................................................................. 79
Figure 4.16: Extraction of Np(V) by variation of Et(p)TDPA concentration from various
nitric acid concentrations .................................................................................................. 81
Figure 4.17: Comparison of Np (solid) and Pa (dashed) extraction by Et(p)TDPA......... 84
Figure 4.18: Extraction of protactinium by 0.2 M EtTDPA from nitric acid solutions .... 85
Figure 4.19: Extraction of thorium with EtTDPA from 3 M HNO in FS-13 .................. 87
3
Figure 4.20: Thorium extraction with 0.001 M EtTDPA from nitric acid ....................... 88
Figure 4.21: Plutonium redox potentials vs. SHE for 1 M HClO ................................... 90
4
Figure 4.22: Plutonium(IV) extraction by EtTDPA from 3 M HNO in FS-13 ............... 91
3
Figure 4.23: Separation of the actinides from trivalent lanthanides at 3 M nitric acid with
0.2M Et(o)TDPA .............................................................................................................. 95
Figure 4.24: Separation of the actinides from trivalent lanthanides at 3 M nitric acid with
0.2 M Et(m)TDPA ............................................................................................................ 96
Figure 4.25: Separation of the actinides from trivalent lanthanides at 3 M nitric acid with
0.2 M Et(p)TDPA ............................................................................................................. 96
Figure 5.1: Event timeline during radiolysis of neutral water (adapted from
Radiochemistry and Nuclear Chemistry 3rd Edition, Choppin) ........................................ 98
Figure 5.2: Acid-catalyzed hydrolysis mechanism of a generic amide .......................... 105
Figure 5.3: IR spectra of carbonyl the region of acid saturated Et(p)TDPA at varying
absorbed dose .................................................................................................................. 106
Figure 5.4: Gas chromatograph of Et(o)TDPA in FS-13 ................................................ 109