forbes research group tori forbes w374 [email protected]
TRANSCRIPT
Fundamental Structural Chemistry
of Actinides
Formation of colloids/nanoparticles
through hydrolysis
Transport of Nuclear Waste in the Environment
Novikov et al., Science 2008
Research Focus of Forbes Group
Nuclear Waste
Legacy of Environmental Contamination
Over 1,000 locations in the US are contaminated with radiation.
19 sites on National Priority List88 million gal waste in 230 underground tanks (some leaking)Contaminated groundwater = 1.15 x 1010 galContaminated Soil and Sediment = 75 million m3
5 sites account for 71% of the remediation work:
Rocky Flats, CO
Idaho National Laboratory, ID
Savannah River, SC
Oak Ridge, TN
Hanford, WA
Project 1: Hanford
U.S. Department of EnergyLichtner et al., Comp. & Geo. 2003
Separations process at HanfordSludge
5 M NaOH, pH14 Boehmite (AlOOH)And An(OH)x solid
+Soluble Al(OH)3
Vitrified into glass waste
Nitric acid Soluble An and Al3+ species ?
We have no current knowledge of the chemical species that form when actinides and other metals (such as aluminum) undergo hydrolysis…
Hydrolysis products cause problems in separations (fouling of chromographic columns, incomplete separations, salting out), leading to delays in remediation and huge additional expense.
Synthesis and Crystal Structure Determination
[Th2Al6(OH)14(H2O)12(HEDTA)2](NO3)6(H2O)12
Monoclinic, P21/ca = 11.198 Åb = 13.210 Åc = 23.115 Å
α = 90°β = 96.375°γ = 90°
R1 = 0.0316, Rwp =0.0851 GOF = 1.10
Fairley, Unruh, Abeysinghe, and Forbes, In preparation
Project 2: The Plutonium Problem!At the source
239,240Pu = 1000 bec/L
Well 41/77 (0.5 km) 239,240Pu = 4.8 bec/L
Well 3/68 (2 km) 239,240Pu = 1.62 bec/L
Well 14/68 (4 km) 239,240Pu = 0.3 bec/L
Acceptable EPA limits for drinking water (total
radioactivity) = 0.55 bec/L
Novikov et al., Science, (2008)
Small particles/colloids are to blame!
Novikov et al., Science, (2008)
Adsorption of actinides
We can not predict the mobility of plutonium in the
environment!
We have no molecular understanding of small
nanoparticles!
Colloidal transport in the Environment
Colloidal Particles Aggregation in solution Precipitation of colloidal “floc”
Colloidal Particles Aggregation in solution Precipitation of colloidal “floc”
Overall Question: What are the structural characteristics of the
colloidal particles??
Are molecular clusters the building blocks?
Johansson Acta. Chem. Scand. (1960); Roswell and Nazar., J. Am. Chem. Soci. (2000); Forbes and Abeysinghe, in preparation; Allouche et al, Angew. Che. Int. Ed (2000); Sun et al., Inorg Chem. (2011).
Al26 Al30 Al32
ε-Al13
δ-Al13
Pair-distribution function analysis
High energy X-ray scattering technique
Advanced Photon Source, Argonne National Laboratory, Beamline 11-1D-B
58.26 keV, wavelength = 0.2127 Å
Structure Characterization of Colloidal “Floc”
Colloidal “Floc”Molecular cluster
Models for contaminant transport…
Abeysinghe and Forbes, In preparation
[(Zn(NTPA)(H2O))2Al2(NPTA)2Al30O8(OH)62(H2o)2o](2-6NDS)5 [(Cu(H2O)2)2Al30O8(OH)60(H2o)22](2-6NDS)9
Potential Projects
• Aluminum-actinide chemistry – What
waste products are likely to form at
the Hanford Site in Washington state?• Aluminum “floc”– pH changes, thermal restructuring• Extension to iron oxyhydroxide, manganese oxides and
actinides (Th, U, Np?, Pu?) • Linking laboratory experiments to environmental systems• Developing fluorescent tags or radiotracer techniques to
track nanoparticles in environmental systems• Novel materials for advanced remediation strategies
Current Group membersSamangi AbeysingheJacob ErtmanMelissa FairleyErin FloresAnna LiboKyle GojdasEric JetterDr. Daniel Unruh
Fundamental Actinide Chemistry (Th, U, Np)
Formation nanoparticles
or nanominerals
Transport of Nuclear Waste in the Environment
Novikov et al., Science 2008
Tori Forbes, W374, [email protected]