Metal Release and Speciation Changes during Wet Aging of Coal Fly Ashes

Transcription

1 Supporting Information for: Metal Release and Speciation Changes during Wet Aging of Coal Fly Ashes Jeffrey G. Catalano 1 *, Brittany L. Huhmann 1, Yun Luo 1,2, Elizabeth H. Mitnick 1, Adam Slavney 1, Daniel E. Giammar 2 1. Department of Earth and Planetary Sciences, Washington University, Saint Louis, MO 63130, USA 2. Department of Energy, Environmental, and Chemical Engineering, Washington University, Saint Louis, MO 63130, USA * Corresponding author: Tel: Fax: catalano@eps.wustl.edu Department of Civil and Environmental Engineering, University of Iowa, Iowa City, IA Gemological Institute of America, Carlsbad, California Number of Figure: 0 Number of Tables: 7 Number of Pages: 10 S1

2 Table S1. Minimum detectable concentrations (MDCs) of elements by ICP-MS for the two ash studies. Element Class C Ash Study MDC (mg L -1 ) Class F Ash Study MDC (mg L -1 ) Ca Al 5 25 Mg Fe Cr Cu Zn As Se Ba S2

3 Table S2. Compositions of the unreacted fly ash samples. Analyte Class C Class F major elements (wt%) a SiO ± 0.1 b 46.3 ± 0.2 TiO ± ± 0.01 Al 2 O ± ± 0.2 Fe 2 O ± ± 0.1 MnO 0.03 ± ± 0.01 MgO 4.9 ± ± 0.1 CaO 24.3 ± ± 0.02 Na 2 O 1.7 ± ± 0.1 K 2 O 0.56 ± ± 0.02 P 2 O ± ± 0.01 LOI c volatiles (wt%) d C 0.05 ± ± 0.4 S 0.64 ± ± 0.05 trace elements (ppm) e V 249 ± ± 5 Cr 71 ± ± 5 Co 27 ± 5 55 ± 5 Ni 90 ± ± 4 Cu 232 ± ± 3 Zn 234 ± ± 4 Ga 42 ± 2 60 ± 2 As 30 ± ± 3 Se 6 ± 3 7 ± 3 Rb 26 ± ± 2 Sr 3140 ± ± 3 Zr 178 ± ± 2 Nb 32 ± 1 25 ± 1 Ba 6430 ± ± 15 Pb 50 ± ± 6 U 10 ± 2 22 ± 2 a Weight percent as oxide components determined by XRF. b Reported errors represent experimental precisions (2σ) based on counting statistics. c Mass loss on ignition (LOI), representing the mass sum of all elements volatilized during fusion of a sample into a glass disc for major element XRF analysis. d Weight percent carbon and sulfur determined by elemental analysis: these may volatilize during XRF sample preparation. e mg of trace element per kg of sample determined by XRF. S3

4 S1. PHASE IDENTIFICATION FROM X-RAY DIFFRACTION DATA Crystalline phases in the unreacted and reacted fly ash samples were identified based on their peak positions and their approximate relative intensities (Table S3). These were calculated from crystal structures using the program XPOW. S1 Table S3. Strong diffraction lines of relevant phases that occur between 15 and 45 2θ Mineral d (Å) 2θ ( ) I Mineral d (Å) 2θ ( ) I Anhydrite S Merwinite S Calcite S Mullite S Gehlenite S Hematite S Quartz S Lime S Maghemite S Periclase S S4

5 Table S4. As K-edge EXAFS fitting results for the class C ash in comparison to the calcium pyroarsenate structure. Aging Time Shell N a R (Å) b σ 2 (Å 2 ) c E 0 (ev) d χ 2e ν 0 wk As-O (1) f (8) 7(4) 5.7 As-O-O MS As-As 1 3.4(1) As-Ca 2(2) 3.65(9) wk As-O (1) (6) 6(3) 4.9 As-O-O MS As-As (8) As-Ca 3(2) 3.67(6) wk As-O (1) (6) 7(3) 7.6 As-O-O MS As-As 1 3.4(1) As-Ca 2(2) 3.66(3) wk As-O (1) (6) 7(3) 7.6 As-O-O MS As-As (9) As-Ca 2(1) 3.69(8) Structure Shell N R (Å) S11 Ca 2 As 2 O 7 As-O As-As As-Ca As-Ca As-Ca a Coordination number. b Interatomic distance. c Debye-Waller factor. d Difference in the threshold Fermi level between the data and theory. e Goodness-of-fit parameter. S12 f The estimated standard deviations are listed in parentheses, representing the uncertainty in the last digit. Parameters with no listed uncertainties were not varied in the analyses. S5

6 Table S5. Zn K-edge EXAFS fitting results for the class C ash in comparison to model structures. Aging Time Shell N a R (Å) b σ 2 (Å 2 ) c E 0 (ev) d χ 2e ν 0 wk Zn-O 4.0(5) f 1.97(2) 0.009(3) 3(3) 11.1 Zn-Al/Si 0.4(5) 3.04(9) wk Zn-O Tet 2.8(4) 1.95(4) 0.005(3) 4(4) 2.3 Zn-O Oct 1.8(4) 2.11(6) 0.005(3) Zn-Al/Si 0.9(9) 3.05(7) Zn-C 1(2) 3.0(2) wk Zn-O Tet 2.7(3) 1.96(4) 0.004(3) 7(6) 6.8 Zn-O Oct 2.0(3) 2.13(5) 0.004(3) Zn-Al/Si 1.1(9) 3.03(5) Zn-C 2(2) 2.92(9) wk Zn-O Tet 3.0(4) 1.98(4) 0.005(3) 6(5) 9.7 Zn-O Oct 1.5(4) 2.15(6) 0.005(3) Zn-Al/Si 1.1(6) 3.02(4) Zn-C 1(2) 2.8(1) Structure Shell N R (Å) Smithsonite S4 Zn-O Zn-C Zn-Zn Hydrozincite S13 Zn-O Zn-C Zn-Zn Zn-Zn Zn Layered Double Zn-O 6.4(2) 2.05(1) Hydroxide S14 Zn-Al 1.2(5) 3.09(1) Zn-Zn 4.8(5) 3.09(1) a Coordination number. b Interatomic distance. c Debye-Waller factor. d Difference in the threshold Fermi level between the data and theory. e Goodness-of-fit parameter. S12 f The estimated standard deviations are listed in parentheses, representing the uncertainty in the last digit. Parameters with no listed uncertainties were not varied in the analyses. S6

7 Table S6. As K-edge EXAFS fitting results for the class F ash in comparison to model structures. Aging Time Shell N a R (Å) b σ 2 (Å 2 ) c E 0 (ev) d χ 2e ν 0 wk As-O (1) f (6) 5(3) 9.0 As-O-O MS As-Fe 0.9(6) 3.28(4) wk As-O (1) (6) 6(3) 3.6 As-O-O MS As-Fe 0.7(6) 3.30(5) wk As-O (1) (6) 6(3) 5.6 As-O-O MS As-Fe 1.1(6) 3.29(4) Structure FeAsO4 S15 As-O As-Fe As-Fe Angelellite S16 As-O As-Fe As-Fe As-Fe As-Fe As-Fe As-Fe As-Fe As-As a Coordination number. b Interatomic distance. c Debye-Waller factor. d Difference in the threshold Fermi level between the data and theory. e Goodness-of-fit parameter. S12 f The estimated standard deviations are listed in parentheses, representing the uncertainty in the last digit. Parameters with no listed uncertainties were not varied in the analyses. S7

8 Table S7. Zn K-edge EXAFS fitting results for the class F ash in comparison to model structures. Aging Time Shell N a R (Å) b σ 2 (Å 2 ) c E 0 (ev) d χ 2e ν 0 wk Zn-O 4.0(6) f 1.96(1) 0.008(2) 0(2) 1.5 Zn-Fe 4(2) 3.47(2) 0.007(4) Zn-Zn 2.0(8) 3.62(4) wk Zn-O 3.7(8) 1.97(1) 0.006(2) 2(2) 1.0 Zn-Fe 3(2) 3.48(4) 0.003(7) Zn-Zn 1.6(8) 3.61(4) wk Zn-O 3.9(9) 1.97(2) 0.007(2) 1(3) 2.6 Zn-Fe 5(3) 3.5(1) 0.01(2) Zn-Zn 1(3) 3.6(2) 0.01 Mineral Shell N R (Å) Franklinite S17 Zn-O Zn-Fe Zn-Zn Gahnite S18 Zn-O Zn-Al Zn-Zn Zincite S19 Zn-O Zn-Zn Zn-Zn a Coordination number. b Interatomic distance. c Debye-Waller factor. d Difference in the threshold Fermi level between the data and theory. e Goodness-of-fit parameter. S12 f The estimated standard deviations are listed in parentheses, representing the uncertainty in the last digit. Parameters with no listed uncertainties were not varied in the analyses. S8

9 REFERENCES (S1) Downs, R. T.; Bartelmehs, K. L.; Gibbs, G. V.; Boisen, M. B., Interactive software for calculating and displaying X-ray or neutron powder diffractometer patterns of crystalline materials. Am. Mineral. 1993, 78, (S2) Hawthorne, F. C.; Ferguson, R. B., Anhydrous sulphates. II. Refinement of the crystal structure of anhydrite. Can. Mineral. 1975, 13, (S3) Moore, P. B.; Araki, T., Atomic arrangement of merwinite, Ca 3 Mg[SiO 4 ] 2, an unusual dense-packed structure of geophysical interest. Am. Mineral. 1972, 57, (S4) Graf, D. L., Crystallographic tables for the rhombohedral carbonates. Am. Mineral. 1961, 46, (S5) Angel, R. J.; Prewitt, C. T., Crystal structure of mullite: A re-examination of the average structure. Am. Mineral. 1986, 71, (S6) Swainson, I. P.; Dove, M. T.; Schmahl, W. W.; Putnis, A., Neutron powder diffraction study of the åkermanite-gehlenite solid solution series. Phys. Chem. Miner. 1992, 19, (S7) Maslen, E. N.; Streltsov, V. A.; Streltsova, N. R.; Ishizawa, N., Synchrotron X-ray study of the electron density in α-fe 2 O 3. Acta Crystallogr. 1994, B50, (S8) Antao, S. M.; Hassan, I.; Wang, J.; Lee, P. L.; Toby, B. H., State-of-the-art highresolution powder X-ray diffraction (HRPXRD) illustrated with Rietveld structure refinement of quartz, sodalite, tremolite, and meionite. Can. Mineral. 2008, 46, (S9) Fiquet, G.; Richet, P.; Montagnac, G., High-temperature thermal expansion of lime, periclase, corundum and spinel. Phys. Chem. Miner. 1999, 27, (S10) Pecharromán, C.; González-Carreño, T.; Iglesias, J. E., The infrared dielectric properties of maghemite, γ-fe 2 O 3, from reflectance measurement on pressed powders. Phys. Chem. Miner. 1995, 22, (S11) Pertlik, F., Crystal Structure of Ca 2 As 2 O 7. Mon. Chem. 1980, 111, (S12) Kelly, S. D.; Hesterberg, D.; Ravel, B., Analysis of soils and minerals using X-ray absorption spectroscopy. In Methods of Soil Analysis. Part 5. Mineralogical Methods, Ulery, A. L.; Drees, L. R., Eds. Soil Science Society of America: Madison, WI, 2008; pp S9

10 (S13) Ghose, S., The crystal structure of hydrozincite, Zn 5 (OH) 6 (CO 3 ) 2. Acta Crystallogr. 1964, 17, (S14) Trainor, T. P.; Brown, G. E., Jr.; Parks, G. A., Adsorption and precipitation of aqueous Zn(II) on alumina powders. J. Colloid Interface Sci. 2000, 231, (S15) Reiff, W. M.; Kwiecien, M. J.; Jakeman, R. J. B.; Cheetham, A. K.; Torardi, C. C., Structure and Magnetism of Anhydrous FeAsO 4 : Inter- vs Intradimer Magnetic Exchange Interactions. J. Solid State Chem. 1993, 107, (S16) Moore, P. B.; Araki, T., Angelellite, Fe 3+ 4 O 3 (As 5+ O 4 ) 2 : A novel cubic close-packed oxide structure. Neues Jahrb. Mineral., Abh. 1978, 132, (S17) Levy, D.; Pavese, A.; Hanfland, M., Phase transition of synthetic zinc ferrite spinel (ZnFe 2 O 4 ) at high pressure, from synchrotron X-ray powder diffraction. Phys. Chem. Miner. 2000, 27, (S18) Popović, J.; Tkalčec, E.; Gržeta, B.; Kurajica, S.; Rakvin, B., Inverse spinel structure of Co-doped gahnite. Am. Mineral. 94, (S19) Kihara, K.; Donnay, G., Anharmonic thermal vibrations in ZnO. Can. Mineral. 1985, 23, S10