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Advanced Tools for Environmental and Green Chemistry: SolidState NMR and Chemical Cyberinfrastructur

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Title: Advanced Tools for Environmental and Green Chemistry: SolidState NMR and Chemical Cyberinfrastructur


1
Advanced Tools for Environmental and Green
Chemistry Solid-State NMR and Chemical
Cyberinfrastructure
  • Karl T. Mueller
  • Penn State University
  • Department of Chemistry
  • Materials Research Institute
  • Center for Environmental Chemistry
  • and Geochemistry
  • Center for Environmental Kinetics Analysis

2
Reactivity for Catalysts and Minerals
3
Strontium in the Environment
  • US DOE Hanford Reservation
  • Main US plutonium production facility 1943-1987
  • 240 million gallons of high-level liquid waste
    generated
  • Stored primarily in single-shelled tanks buried
    in vadose zone
  • 67 tank failures
  • Organisms deposit 10 ingested strontium in bone

Photos from T. E. Marceau, D. W. Harvey, D. C.
Stapp, S. D. Cannon, C. A. Conway, D. H. Deford,
B. J. Freer, M. S. Gerber, J. K. Keating, C. F.
Noonan, and G. Weisskopf, (Hanford Cultural and
Historic Resources Program, United States
Department of Energy, Richland, 2002).
4
Cyber-Enabled Chemistry
5
Solid-State NMR at Penn State
6
Solid-State NMR at PNNL
7
Collaborative Cyberinfrastructure Team at Penn
State
Cyberinfrastructure and Research Facilities
Developing Collaboratory Tools to Facilitate
Multi-Disciplinary, Multi-Scale Research in
Environmental Molecular Sciences NSF CHE-0535656
8
NMR Basics - Its the Nuclear Spin
NMR Nuclear Magnetic Resonance
1H, 2H, 7Li, 11B, 13C, 15N, 17O, 19F, 23Na, 27Al,
29Si, 31P
9
NMR of Solids I. The Problem
10
NMR of Solids II The Solution
11
MAS NMR of Solids
29Si MAS of a Zeolite
31P MAS of a Phosphate Glass
Q2
Q1
Si3Al
Si2Al
Si1Al
Si4Al
Si0Al
12
Beyond the Chemical Shift
  • Heteronuclear correlation experiments use
    couplings between the nuclei to probe interatomic
    interactions

13
Beyond the Chemical Shift Multi-Dimensional NMR
31P MAS
1H/31P CPMAS
R. M. Wenslow and K. T. Mueller, J. Phys. Chem. B
102, 9033 (1998)
14
Comparing and ContrastingOxide Surfaces
  • In many instances, we are interested in
    processes at low surface-area interfaces (e.g.
    mineral dissolution, weathering of glass plates
    or monoliths, etc.).
  • How do we correlate reactivity (rates) to
    surface structure and reactive surface area ?

Amorphous Solids Fiber Surfaces
Crystalline Solids Minerals
Amorphous Solids Plates and Powders
15
Connection to Mineral Dissolution
N. Tsomaia, S. L. Brantley, J. P. Hamilton, C. G.
Pantano, and K. T. Mueller, American
Mineralogist, 88, 54-67 (2003)
16
Previous Studies
FTIR - The analysis depth is gt 1mm. SIMS -
Depth sensitivity is limited to 200-500 Å. XPS -
The outermost 90 Å is analyzed.
17
Solid-State NMR Analysis Proton Localization
x 0.4 glass, pH 2, 1000 h
27Al MAS
1H/27Al CPMAS
18
1H/27Al CPMAS Results
19
Relative Amounts of Six-Fold Al Species
  • Fraction of Al(VI) dependent on Al/Si in bulk
    does not correlate with amount of Al in outermost
    layer (90 Å) as measured by XPS. Albite crystal
    data is anomalous.
  • Lack of correlation with leachate Al
    concentration argues against back precipitation
    of Al(VI) containing phases.

20
Aluminum Coordination During Transformation
Simulations
The formation of AlVI (or here, 6Al) in situ on
a feldspar surface has significant implications
for the dissolution mechanism and surface
chemistry.
L. J. Criscenti, S. L. Brantley, K. T. Mueller,
N. Tsomaia, and J. D. Kubicki, Geochimica et
Cosmochimica Acta 69, 2205-2220 (2005).
21
Model for Mechanism
22
27Al MAS NMR of Nepheline Glass
23
Acid Leaching Studies Conclusions
  • Modeling results are extremely sensitive to
    initial geometries (esp. of water molecules).
    Larger calculations are being undertaken.
  • The fully relaxed structures used are actually
    more representative of glass surface reactivity.
  • Calculated isotropic shifts allow us to
    hypothesize that we are observing Q1 6Al.

24
Environmental Kinetics Analysis
  • Identification of reactive sites on surfaces in
    the environment
  • Dissolution
  • Precipitation
  • Bioreaction
  • Quantification of reactive sites
  • Total reactive species (e.g., -OH groups)
  • Speciation (Al-OH, Si-OH, other)
  • Scaling of reaction rates

25
A Solid-State NMR Approach
  • Isotopic selectivity
  • Selective chemistry
  • Molecular-level information
  • Chemical shift, T1, and other NMR parameters are
    sensitive to
  • Type of bonding
  • Motion
  • Coordination environment
  • Must overcome low sensitivity
  • Use nuclei such as 19F or 31P
  • Probe molecule containing CF3 moiety
  • TFS (3,3,3-trifluoropropyl)dimethylchloros
    ilane

26
TFS Surface Modification
First used in our group to investigate low
surface area glass fibers.
R. Fry, N. Tsomaia, C. Pantano, and K. T.
Mueller, J. Am. Chem. Soc. 125, 2378 (2003).
27
TFS Surface Modification
First used in our group to investigate low
surface area glass fibers.


TFS in mesopores
TFS on planar surface
28
Particle Surface Area
Geometric
BET
29
Dissolution Rate Normalization
Geometric
BET
Dissolution conditions pH 4
Wolff-Boenisch et al. 2004, GCA, 68 4843
30
Dissolution Rate vs. BET Surface Area
31
OH/g vs. BET Surface Area
32
A Comparison
33
Rate Dependence on Hydroxyl Density
34
Hydroxyl Normalized Dissolution
35
Reactive Surface Area Conclusions
  • Reactive hydroxyl group measurement via an NMR
    active probe molecule (TFS) has been
    accomplished.
  • The correlation between the measured reactive
    hydroxyl site density and the dissolution rate
    under acidic conditions is excellent.
  • Hydroxyl site density may be the appropriate
    normalization factor for dissolution kinetics.

36
Transport and Fate of Radionuclides in the
Hanford Vadose Zone
Principal Investigators Jon Chorover
(University of Arizona) Karl T. Mueller (Penn
State University) Peggy A. ODay (Arizona State
University) R. Jeff Serne (Pacific Northwest
National Laboratory)
React clay and sediments with STWL in suspension
from 0 to 2 yr 2 M (NaNO3), 0.05 M Al(OH)4- pH
13.8 (NaOH), Cs Sr 10-5
to 10-3
37
Kaolinite Dissolution and Neophase Formation
Changes in Si
Chemical Formula Si4Al3.66Fe(III).07
Ti0.16O10(OH)8
38
Kaolinite Dissolution and Neophase
Formation
Initial 10-5 M 10-4 M
10-3 M
Cs
Cs
Cs
Sr
Sr
Sr
39
27Al MAS NMR Spectra of Kaolinite Transformation
0 ppm
60 ppm
40
Al Coordination Ratio from Solid-State NMR
41
Solid-State NMR at PNNL
42
Kaolinite Dissolution and Neophase Formation
PQ CQ (1 ?2/3)1/2
43
Kaolinite Dissolution and Neophase Formation
44
Strontium Legacy of Plutonium Production
  • US DOE Hanford Reservation
  • Waste known to cause mineral transformation
  • Minerals known to take up strontium
  • Environmental fate of radionuclides unknown
  • Strontium sequestration and interactions with
    clays and zeolites not well understood

Sr Sequestration by STWL Weathered Kaolinite
Initial 10-3 M Sr
Non-extractable
Mg - exchangeable
Oxalate extractable
Chorover, J. Choi, S. K. Amistadi, M. K.
Karthikeyan, K. G. Crosson, G. Mueller, K. T.
Environ Sci Technol 2003, 37, 2200-2208.
Learn about the behavior of strontium in the
environment by studying the interactions of
strontium nuclei in natural minerals and zeolites
using solid-state nuclear magnetic resonance
(NMR).
45
Solid-State NMR of 87Sr
  • Quadrupolar Interaction in NMR
  • Molecular-level interactions that depend on local
    symmetry and electronic structure

Quadrupolar Interaction
NMR parameters describe the cation sites in
materials Sensitive to coordination, bonding,
neighboring nuclei
46
Strontium (87Sr) NMR Sensitivity!
no splitting or broadening
spin - 9/2
x 500,000
non-zero Cq
47
Sensitivity Enhancement - Quadrupolar Nuclei
  • Hahn-echos and Quadrupolar Carr-Purcell-Meiboom-Gi
    ll (QCPMG)
  • Increase External Field Strength

48
Static 87Sr NMR at 21.14 T
Strontianite
Cq 8.9 MHz ? 0.14
Photo courtesy of Pacific Northwest National
Laboratory, Richland, Washington.
Frequency (ppm from 1 M SrCl2)
49
Static 87Sr NMR at 21.14 T
Celestine 12 coordinate Sr Links to 7 sulfate
tetrahedra Cq 28.1 MHz h 0.7
Frequency (kHz from 1 M SrCl2)
50
Even More Enhancement for 87Sr NMR
  • Continue quest for enhanced sensitivity
  • Preparatory pulse schemes
  • Study strontium in other systems
  • Organics
  • Hydroxyapatite
  • Silicate/phosphate glasses and other inorganic
    materials

S 9?
S 5?
S ?
51
Strontium Sequestered in a Mica
52
Developing Collaboratory Tools to Facilitate
Multi-Disciplinary, Multi-Scale Research in
Environmental Molecular Sciences Cyber-Enabled
Chemistry
Our project will focus on software development to
collect, analyze, and distribute data to
scientists working on environmental chemistry
problems.
53
PSU Cyberchemistry Team
  • Karl T. Mueller - experimental physical chemistry
    (surfaces in the environment)
  • Barbara Garrison - theoretical physical chemistry
    (QM, MD, MC calculations, surfaces in general)
  • Lee Giles - cyberchemistry search engine and
    digital library design and development
  • Prasenjit Mitra - designing and implementing
    automated tools for information integration
  • James Kubicki - CEKA Assistant Director, quantum
    chemical calculations on environmental problems
  • Joel Bandstra - CEKA Kinetic Synthesis Specialist

54
Acknowledgements
  • NSF I/UCRC for Glass Research
  • (NSF-E9908423)
  • Penn State Biogeochemical Research Initiative for
    Education
  • (NSF DGE-9972759)
  • Penn State Center for Environmental Kinetics
    Analysis
  • (NSF CHE-0431328)
  • United States Department of Energy
  • (DE-FG07-99ER15012)
  • Cyberinfrastructure and Research Facilities
    Developing Collaboratory Tools to Facilitate
    Multi-Disciplinary, Multi-Scale Research in
    Environmental Molecular Sciences
  • (NSF CHE-0535656)
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