Heavy metal adsorption on iron oxide and iron oxide-coated silica ...

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Figure 7.3 Fourier transform and fit of Pb standards spectra at Pb LIII edge. FT wasperformed over range: PbO 3.0-10.8 A l , PbCO3 2.08-9.79 A l , Pb 2+ 2.26-8.48 A l , PbOwas fitted over 0.74-3.95 A, PbCO3 0.46-4.69 A, and Pb 2+ 0.42-3.0 A. Lines representdata, dashed lines represent fit.90
910.08 A. This octahedral structure represents that of fully hydrated Pb(II), as greater than99% of the total Pb exists as Pb 2+ in this aqueous sample. This result is consistent withother studies (Bargar et al. 1997a; Elzinga and Sparks, 2002).All spectra of Pb/HFO sorption samples are different from those of PbO, PbCO3,and aqueous Pb(NO3)2 (Figure 7.1 and Figure 7.2), suggesting unique structures fromthese standards. Overall, the spectra are dominated by the backscattering from a firstshell of O atoms and beat features at 4.5 — 5.0 A 1 and 6.5 — 8.5 A-1 indicative of a heavierbackscatter from second shell contributions. The x(k)•k 3 spectra were Fouriertransformed over the range 2.8 — 9.5 A -1 and fitted over the range 0.45 — 3.58 A with aFe-substituted PbO model generated theoretically using FEFF7 (Zabinsky et al. 1995).The RSFs show two peaks at —1.9 A and —2.9 A (Figure 7.4 and Figure 7.5), and fitting(Table 7.3) reveals 1.27 — 2.92 O atoms at 2.25 — 2.30 A for the first shell. The secondshell could only be fit with Fe atoms and resulted in 0.92 — 2.05 Fe atoms at 3.29 — 3.34A. The experimental amplitude and phase were reproduced by the fitting (Figure 7.4 andFigure 7.5). However, the larger Debye-Waller factor for the second shell (Table 7.3)suggests greater variation in the Pb-Fe distances than those for Pb-O.The absence of Pb backscatters around the central atom suggests that the adsorbedPb(II) ions on HFO are isolated mononuclear complexes. The absence of O as a secondshell and the tighter Pb-O distances as compared to the hydrated form observed indicatethat the waters of hydration were lost upon <strong>adsorption</strong> to HFO. Other EXAFSinvestigations (Manceau et al. 1992; Scheinost et al. 2001; Trivedi et al. 2003) reportedthat the adsorbed Pb(II) on ferrihydrite results in two O atoms at 2.3 A and less than oneto two Fe atoms at around 3.3 A. The fitting results of this study are similar with those
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Copyright Warning & RestrictionsThe
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ABSTRACTHEAVY METAL ADSORPTION ON I
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HEAVY METAL ADSORPTION ON IRON OXID
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APPROVAL PAGEHEAVY METAL ADSORPTION
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Fan, M.; Boonfueng, T.; Xu, Y.; Axe
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ACKNOWLEDGMENTI would like to expre
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TABLE OF CONTENTS(Continued)Chapter
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TABLE OF CONTENTS(Continued)Chapter
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LIST OF TABLES(Continued)TablePageB
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LIST OF FIGURES(Continued)FigurePag
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LIST OF FIGURES(Continued)FigurePag
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CHAPTER 1INTRODUCTIONHeavy<
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3and Sigg, 1992; Gunneriusson et al
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CHAPTER 2OXIDES AND THEIR EFFECT ON
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7et al. 1996; Green-Pedersen et al.
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9identify components, distribution,
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11oxides. Because extraction method
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13Table 2.2 Some Coating Work and C
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15increasing the sorbate concentrat
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17mole Cu g-1 goethite (-1-7% of th
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19Overall, macroscopic adso
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21hematite (up to 9.9 limo' Pb ril-
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23concentration in their system was
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25Surface complexation modeling (SC
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27Overall, surface complexation mod
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29Spectroscopic techniques, especia
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31• Understand the effect of comp
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33existing in almost all soils and
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CHAPTER 4EXPERIMENTAL METHODSIn thi
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37included coating temperature (T),
Page 61 and 62: 39generated at 45 kV and 40 mA, sca
Page 63 and 64: 41PZC include electrophoretic mobil
Page 65 and 66: 43Lin-edge, from 8,133 to 8,884 eV
Page 67 and 68: CHAPTER 5CHARACTERIZATION OF IRON O
Page 69 and 70: 47measured by potentiometric titrat
Page 71 and 72: Table 5.2 XRD Data of Alfa Aesar (A
Page 73 and 74: 51Table 5.3 XRF Results for Alfa Ae
Page 75 and 76: Figure 5.4 Particle size distributi
Page 77: 55Figure 5.5 ESEM micrograph for Al
Page 80 and 81: 585.2.5 Surface Charge Distribution
Page 82 and 83: Figure 5.10 Potentiometric titratio
Page 84 and 85: CHAPTER 6SYNTHESIS AND CHARACTERIZA
Page 86 and 87: Figure 6.1 Comparison between Fecon
Page 88 and 89: Figure 6.2 XRD patterns for goethit
Page 90 and 91: 68iron oxide coatings at 60 °C, go
Page 92 and 93: 70substrate diameter of 0.2 mm, an
Page 94 and 95: 72goethite and silica results in on
Page 96 and 97: Figure 6.7 ESEM micrograph (9000x)
Page 98 and 99: 76Furthermore, because discrete goe
Page 100 and 101: 78Table 6.2 Surface Area and Porosi
Page 102 and 103: Figure 6.10 Surface charge distribu
Page 104 and 105: Figure 6.11 Ni adsorption</
Page 106 and 107: 84that for pure silica, and the goe
Page 108 and 109: Table 7.1 Sample Preparation Condit
Page 110 and 111: Figure 7.2 EXAFS spectra of Pb/HFO
Page 114 and 115: Figure 7.4 Fourier transform and fi
Page 116 and 117: Table 7.3 EXAFS Results of Pb/HFO S
Page 118 and 119: 967.2 Fe XAS of Iron Oxides and Pb/
Page 120 and 121: Figure 7.7 EXAFS spectra of iron ox
Page 122 and 123: 100and Venturelli, 1999). Overall t
Page 124 and 125: 102(hematite, goethite, akaganeite,
Page 126 and 127: 104adsorption proc
Page 128 and 129: 106of pH, ionic strength, Pb loadin
Page 130 and 131: Figure 8.1 Ni adsorption</s
Page 132 and 133: 110high metal load
Page 134 and 135: Figure 8.3 x(k)•k3 spectra and Fo
Page 136 and 137: Figure 8.4 (k)•k3 spectra of Ni-H
Page 138 and 139: Figure 8.5 Fourier transforms (magn
Page 140 and 141: 118be fit using either Fe or Ni ato
Page 142 and 143: 1208.3 EXAFS Analysis of FeThe x(k)
Page 144 and 145: Table 8.4 EXAFS Results of HFO and
Page 146 and 147: CHAPTER 9SURFACE COMPLEXATION MODEL
Page 148 and 149: Figure 9.1 Potentiometric titration
Page 150 and 151: 128Table 9.1 Surface Reactions and
Page 154 and 155: 132Table 9.2 Model Parameters for N
Page 158 and 159: 1369.3 Zn Adsorption on GoethiteReg
Page 160 and 161: Figure 9.6 Zn adsorption</s
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140data over a broad range of condi
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142Figure 9.8 Ni adsorption
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144oxide-coated silica. Ni and Zn s
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Figure 10.1 Ni adsorption</
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Figure 10.2 Zn adsorption</
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Figure 10.4 Ni adsorption</
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152one for GACS (2.77x10 -6 mole si
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Figure 10.6 Zn adsorption</
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CHAPTER 11CONCLUSIONS AND FUTURE WO
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158surfaces are needed for successf
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Figure A.2 Ni speciation in 1x10 -5
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Figure A.4 Pb speciation in 5x10 -8
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Figure A.6 Zn speciation in 1x10 -5
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166Table B.2 Potentiometric Titrati
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168Table BA Potentiometric Titratio
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170Table C.3 Zn Adsorption Edges on
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APPENDIX DADSORPTION STUDIES ON SIL
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174Table D.5 Zn Adsorption Isotherm
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176Table E.3 Pb CBC Study on 0.3 g
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APPENDIX GINTRAPARTICLE DIFFUSION M
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180DofA = flier ^ 2fA = Exp(-fD * f
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REFERENCES1. Adamson A. W. (1982) P
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18426. Blake R. L., Hessevick R. E.
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18650. Combes J. M., Manceau A. and
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18876. Elzinga E. J. and Sparks D.
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190102. Gupta V. K. (1998) Equilibr
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192126. Joshi A. and Chaudhuri M. (
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194150. Liu C. and Huang P. M. (200
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196175. Muller B. and Sigg L. (1992
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200. Perry R. H. and Green D. W. (1
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200226. Scheinost A. C., Kretzschma
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202252. Swallow C. K., Hume D. N. a
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204278. Villalobos M., Trotz M. A.
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304. Zhong Z. Y., Prozorov T., Feln
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