FORBES RESEARCH GROUP
Tori Forbes
W374
tori-forbes@uiowa.edu
Research Focus of Forbes Group
Fundamental
Structural Chemistry
of Actinides
Transport of Nuclear
Waste in the
Environment
Novikov et al., Science 2008
Formation of
colloids/nanoparticles
through hydrolysis
Nuclear Waste
Legacy of Environmental Contamination
Over 1,000 locations in the US are contaminated with
radiation.
19 sites on National Priority List
88 million gal waste in 230 underground tanks (some leaking)
Contaminated groundwater = 1.15 x 1010 gal
Contaminated 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 Energy
Lichtner et al., Comp. & Geo. 2003
Separations process at Hanford
Sludge
5 M NaOH, pH14
Boehmite (AlOOH)
And An(OH)x solid
+
Soluble Al(OH)3
Nitric acid
?
Soluble An and
Al3+ species
Vitrified into
glass waste
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/c
a = 11.198 Å
b = 13.210 Å
c = 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!
Adsorption of actinides
We can not predict the
mobility of plutonium in the
environment!
We have no molecular
understanding of small
nanoparticles!
Novikov et al., Science, (2008)
Colloidal transport in the Environment
Overall Question: What are the
structuralAggregation
characteristics
of
the
Precipitation
of
Colloidal Particles
in solution
colloidal “floc”
colloidal particles??
Colloidal Particles
Aggregation in solution
Precipitation of
colloidal “floc”
Are molecular clusters the building blocks?
ε-Al13
δ-Al13
Al26
Al30
Al32
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).
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…
[(Zn(NTPA)(H2O))2Al2(NPTA)2Al30O8(OH)62(H2o)2o](2-6NDS)5
Abeysinghe and Forbes, In preparation
[(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 members
Samangi Abeysinghe
Jacob Ertman
Melissa Fairley
Erin Flores
Anna Libo
Kyle Gojdas
Eric Jetter
Dr. Daniel Unruh
Tori Forbes, W374, tori-forbes@uiowa.edu
Fundamental Actinide
Chemistry
(Th, U, Np)
Transport of Nuclear
Waste in the
Environment
Novikov et al., Science 2008
Formation
nanoparticles
or nanominerals