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In-situ investigations of materials and solutes in supercritical aqueous fluids

In-situ investigations of materials and solutes in supercritical aqueous fluids Robert A. Mayanovic Missouri State University Collaborators:

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In-situ investigations of materials and solutes in supercritical aqueous fluids

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  1. In-situ investigations of materials and solutes in supercritical aqueous fluids Robert A. Mayanovic Missouri State University Collaborators: Hao Yan, NaveenDharmagunawardhane, Joe Demster (Missouri State U.) Alan J. Anderson, Peter R. Meredith(St. Francis Xavier U.) William A. Bassett(Cornell U.) Chris Benmore(APS) Sakura Pascarelli(ESRF) & GiulianaAquilanti(ELLETRA) ReinhardBoehler(CIW) With special thanks to: Steve Heald& Robert Gordon (PNC/XOR - APS); Ram Gupta (MSU); Dave Mao (CIW) Support: Support provided as part of the EFree, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001057. This study was also funded by a Natural Sciences and Engineering Council of Canada (NSERC) collaborative research grant to A.J.A..

  2. Outline • Solubility of MoO3 and transport properties of Mo6+ in H2O2-H2O solutions to 600 °C. • Kinetic study of synchrotron x-ray induced radiolytic reactions of Fe2+ and Fe3+ in supercritical aqueous fluids. • Reactivity, surface structure, and magnetic properties of metal ions and Fe3O4 NP in SCW. • High energy x-ray diffraction of aluminosilicate melt-water system; nanocrystalline CVD diamond rings.

  3. MoO3 in H2O2-H2O System: Experimental Setup

  4. Modified Bassett-type Hydrothermal Diamond Anvil Cell

  5. Mo K-edge XAS Spectral Analysis Fourier transform of the k2c data from Mo K-edge EXAFS spectra of MoO3 in H2O2 at 400 °C Mo K-edge XANES spectra of Mo6+ in a 1M H2O2 aqueous solution at 400-600°C Yan, Mayanovic, Anderson, Meredith, Nucl. Instr. Methods. Phys. Res. A, submitted.

  6. Kinetic Study of Radiolytic Reactions in Supercritical Fe(II)Cl2 Aqueous Fluids Microscope Detector HDAC Temperature Controller

  7. Fe K-edge ED-XANES Spectra Measured at 300 °C The Fe K-edge energy (Eo) was determined by fitting Lorentzian peak-curves to the derivative of each XANES spectrum.

  8. [Fe2+] [FeT] [Fe3+] [FeT] Normalized [Fe2+] and [Fe3+] concentrations versus time, measured from the 0.69 m Fe (II)Cl2 aqueous solution at 300 °C. Eo = xEo2+ + yEo3+, where Eo2+ and Eo3+are Fe K-edge energies of Fe2+ and Fe3+ species, respectively. x = [Fe2+]/[FeT] and y = [Fe3+]/[FeT] Using x + y = 1, we have: [Fe2+] = [FeT](Eo3+- Eo)/(Eo3+- Eo2+)and [Fe3+] = [FeT](Eo- Eo2+)/(Eo3+- Eo2+)

  9. Kinetic data for the 0.69 mFe(II)Cl2aqueous solution to 500 °C. Kinetic rate constants determined from fitting of the data using a general equation y = yo+ A1e-k’1t+ A2e-k’2t .

  10. Reactions of Fe2+ and Fe3+ with Radiolytic Products Oxidation of Fe2+ species most likely occurs according to the Fenton type reaction: Fe2+ + H2O2 → Fe3+ + HO + •OH k2,est = 2 x 103 M-1s-1 Reduction of Fe3+ species most likely occurs according to the two-step reaction: Fe3+ + H2O2 ↔ FeOOH2+ + H+ FeOOH2+ → Fe2+ + •O2H k2,est = 0.2 – 1 x 104 M-1s-1 Takagi and Ishigure, Nucl. Sci. Engin. 89, 177 (1985). Rush and Bielski, J. Phys. Chem. 89, 5062 (1985). Mayanovic, Dharmangunawardhane, Anderson, Pascarelli, Aquilanti, in preparation.

  11. Metal Ion Reactivity with Fe3O4NP in Supercritical Aqueous Fluids

  12. M (Ni,Zn,Co) K-edge XANES Spectra Co2+ is more reactive than Zn2+ or Ni2+ with Fe3O4NP in high PT aqueous fluids.

  13. XANES of (M:Zn,Co)-Fe3O4NP and MFe2O4 Compounds Zn K-edge Co K-edge Co2+, Ni2+, and Zn2+ undergo bonding on surface of Fe3O4NP.

  14. Analysis of M-Fe3O4NP EXAFS Fourier transforms of M-Fe3O4NP k3c data.

  15. Partial structure results from analysis of Ni-Fe3O4NPEXAFS. Mayanovic, Yan, Anderson, Meredith, Bassett, in preparation.

  16. Ni surface layer overgrowth of Fe3O4NPs in supercritical aqueous fluid Local structure Local structure 500 °C 400 °C

  17. Preferential metal-ion site adsorption on Fe3O4NP in supercritical aqueous fluid Zn2+ adsorbs on tetrahedral sites of Fe3O4NPs. Ni2+ and Co2+ adsorb on octahedral sites of Fe3O4NPs.

  18. Simplified Molecular Orbital Diagram for an Octahedral MX6 (M: 3-d metal) Complex Burdett et al., J. Am. Chem. Soc. 104, 92 (1982).

  19. SEM of Fe3O4 and Ni:Fe3O4NP Fe3O4 Ni:Fe3O4

  20. SQUID Measurements Inversion of hysteresis is due to interface exchange of two magnetic phases; can be modeled using: M = MAcosqA+ MBcosqB . O’Shea and Al-Sharif, J. Appl. Phys. 75, 6673 (1994).

  21. Magnetization vs. Temperature Blocking temperature (TB) increases with NP size.

  22. High energy x-ray diffraction Perkin Elmer a-Si flat plate detector 40cm x40cm The x-ray intensity versus momentum transfer Q measured from NaCl in a milled diamond anvil. 11-ID-C: APS Incident energy: 115 KeV Q-range: 0.2 to 40 Å-1 Detector pixel res.: 0.2 x 0.2 mm2 Anderson, Meredith, Bassett, Mayanovic, Benmore, Proc. CNS 2nd Canada-China SCWR Workshop, Toronto, April 25-28 (2010).

  23. Nanocrystalline CVD diamond rings. nanocrystalline CVD x-ray beam 0.8 mm

  24. Conclusions • XAS results indicate that the MoO42- is the predominant species in the H2O2-bearing aqueous solution from 400 to 600 °C. • ED-XAS data show that radiolysis reactions result in oxidation at 300 °C and reduction of iron species at 400 to 500 °C in aqueous fluids. • Zn2+ is preferentially adsorbed on tetrahedral sites and Ni2+ and Co2+ on octahedral sites of Fe3O4 NP at high PT aqueous fluids.

  25. EXAFS Analysis: Constructing a Model FEFF8 and IFEFFIT software are used for EXAFS analysis.

  26. Inverse Fourier Transform of k3c M-Fe3O4NP Data

  27. Coercivity as a function of nanoparticle size After Leslie-Pelecky et al., 1996. Chem. Mater. 8, 1770 - 1783.

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