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The chemistry of TALSPEAK: A review of the science

Journal Article · · Solvent Extraction and Ion Exchange
 [1]
  1. Washington State Univ., Pullman, WA (United States)
Here, the TALSPEAK Process (Trivalent Actinide Lanthanide Separation with Phosphorus-reagent Extraction from Aqueous Komplexes) was originally developed at Oak Ridge National Laboratory by B. Weaver and F.A. Kappelmann in the 1960s. It was envisioned initially as an alternative to the TRAMEX process (selective extraction of trivalent actinides by tertiary or quaternary amines over fission product lanthanides from concentrated LiCl solutions). TALSPEAK proposed the selective extraction of trivalent lanthanides away from the actinides, which are retained in the aqueous phase as aminopolycarboxylate complexes. After several decades of research and development, the conventional TALSPEAK process (based on di-(2-ethylhexyl) phosphoric acid (extractant) in 1,4-di-isopropylbenzene (diluent) and a concentrated lactate buffer containing diethylenetriamine-N,N,N',N",N"-pentaacetic acid (actinide-selective holdback reagent)) has become a widely recognized benchmark for advanced aqueous partitioning of the trivalent 4f/5f elements. TALSPEAK chemistry has also been utilized as an actinide-selective stripping agent (Reverse TALSPEAK) with some notable success. Under ideal conditions, conventional TALSPEAK separates Am3+ from Nd3+ (the usual limiting pair) with a single-stage separation factor of about 100; both lighter and heavier lanthanides are more completely separated from Am3+. Despite this apparent efficiency, TALSPEAK has not seen enthusiastic adoption for advanced partitioning of nuclear fuels at process scale for two principle reasons: 1) all adaptations of TALSPEAK chemistry to process scale applications require rigid pH control within a narrow range of pH, and 2) phase transfer kinetics are often slower than ideal. To compensate for these effects, high concentrations of the buffer (0.5-2 M H/Na lactate) are required. Acknowledgement of these complications in TALSPEAK process development has inspired significant research activities dedicated to improving understanding of the basic chemistry that controls TALSPEAK (and related processes based on the application of actinide-selective holdback reagents). In the following report, advances in understanding of the fundamental chemistry of TALSPEAK that have occurred during the past decade will be reviewed and discussed.
Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE Office of Nuclear Energy (NE)
Grant/Contract Number:
AC05-00OR22725
OSTI ID:
1265492
Journal Information:
Solvent Extraction and Ion Exchange, Journal Name: Solvent Extraction and Ion Exchange Journal Issue: 1 Vol. 33; ISSN 0736-6299
Publisher:
Taylor and FrancisCopyright Statement
Country of Publication:
United States
Language:
English

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Cited By (32)

On the stoichiometry and stability of americium(III) complexes with a hydrophilic SO3–Ph–BTP ligand, studied by liquid–liquid extraction journal December 2015
Enhancing Metal Separations Using Hydrophilic Ionic Liquids and Analogues as Complexing Agents in the More Polar Phase of Liquid–Liquid Extraction Systems journal August 2019
Quantum Chemistry Study on the Extraction of Trivalent Lanthanide Series by Cyanex301: Insights from Formation of Inner- and Outer-Sphere Complexes journal April 2018
Ultra-selective ligand-driven separation of strategic actinides journal June 2019
Spectroscopic and Computational Characterization of Diethylenetriaminepentaacetic Acid/Transplutonium Chelates: Evidencing Heterogeneity in the Heavy Actinide(III) Series journal March 2018
An Americium‐Containing Metal–Organic Framework: A Platform for Studying Transplutonium Elements journal September 2019
Spectroscopic and Computational Characterization of Diethylenetriaminepentaacetic Acid/Transplutonium Chelates: Evidencing Heterogeneity in the Heavy Actinide(III) Series journal March 2018
An Americium‐Containing Metal–Organic Framework: A Platform for Studying Transplutonium Elements journal November 2019
Influence of a Pre‐organized N‐Donor Group on the Coordination of Trivalent Actinides and Lanthanides by an Aminopolycarboxylate Complexant journal January 2019
Enhancing Metal Separations by Liquid–Liquid Extraction Using Polar Solvents journal June 2019
Highly Efficient Extraction of Trivalent f -Cations Using Several N -Pivot Tripodal Diglycolamide Ligands in an Ionic Liquid: The Role of Ligand Structure on Metal Ion Complexation: Highly Efficient Extraction of Trivalent f-Cations Using Several N-Pivot Tripodal Diglycolamide Ligands in an Ionic Liquid: The Role of Ligand Structu journal January 2020
An overview of eight- and nine-coordinate N-donor solvated lanthanoid(III) and actinoid(III) ions journal February 2018
Dissociation rate kinetics of europium-DTPA complexes journal August 2018
Closing the Nuclear Fuel Cycle with a Simplified Minor Actinide Lanthanide Separation Process (ALSEP) and Additive Manufacturing journal September 2019
Hydrophilic sulfonated bis-1,2,4-triazine ligands are highly effective reagents for separating actinides( iii ) from lanthanides( iii ) via selective formation of aqueous actinide complexes journal January 2015
The structure of a lanthanide complex at an extractant/water interface studied using heterodyne-detected vibrational sum frequency generation journal January 2018
Ligands for f-element extraction used in the nuclear fuel cycle journal January 2017
Inner versus outer sphere metal-monoamide complexation: ramifications for tetravalent & hexavalent actinide selectivity journal January 2018
Soft-donor dipicolinamide derivatives for selective actinide( iii )/lanthanide( iii ) separation: the role of S- vs. O-donor sites journal January 2019
Time-resolved and steady-state irradiation of hydrophilic sulfonated bis-triazinyl-(bi)pyridines – modelling radiolytic degradation journal January 2019
Sequestration of trivalent americium and lanthanide nitrates with bis-lactam-1,10-phenanthroline ligand in a hydrocarbon solvent journal January 2019
Dissolution of used nuclear fuel using a tributyl phosphate/n-paraffin solvent journal February 2019
Selective Extraction of Am(III) from PUREX Raffinate: The AmSel System journal December 2015
Thermodynamic Considerations of Covalency in Trivalent Actinide-(poly)aminopolycarboxylate Interactions journal January 2016
Optimization and Single-Stage Centrifugal Contactor Experiments with the Novel Hydrophilic Complexant PyTri-Diol for the i -SANEX Process journal June 2018
Kinetics of Ion Exchange of Zr/Sn(IV) Phosphonate–Phosphate Hybrid Materials for Separation of Lanthanides from Oxidized Actinides journal November 2018
Solvent Extraction of Am(III), Cm(III), and Ln(III) Ions from Simulated Highly Active Raffinate Solutions by TODGA Diluted in Aliquat-336 Nitrate Ionic Liquid journal September 2018
Employing Luminescence to Determine Eu-DTPA Complex Formation Rate Constants in Lactate and Citrate Media: Experiment and Aggregate-Species Kinetic Modelling journal December 2018
Non-Aqueous Electrochemical Fluorination of Used Nuclear Fuel as an Advanced Separation Process journal January 2019
Demand driven salt clean-up in a molten salt fast reactor – Defining a priority list journal March 2018
Optimization and Single-Stage Centrifugal Contactor Experiments with the Novel Hydrophilic Complexant PyTri-Diol for the i-SANEX Process text January 2018
Employing Luminescence to Determine Eu-DTPA Complex Formation Rate Constants in Lactate and Citrate Media: Experiment and Aggregate-Species Kinetic Modelling text January 2019

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