FORBES RESEARCH GROUP Tori Forbes W374 tori-forbes@uiowa.edu

FORBES RESEARCH GROUP

Tori ForbesW374

tori-forbes@uiowa.edu

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, tori-forbes@uiowa.edu