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

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158surfaces are needed for successfully describing <strong>adsorption</strong> on this heterogeneous sorbent.Ni and Zn <strong>adsorption</strong> isotherms reveal more than one sorption mechanism on silica andcoated silica. Although GACS is composed of two types of surfaces, only one type of<strong>adsorption</strong> site was reflected in Ni and Zn isotherms up to 10 .6 M. Polymer formationmay be needed for modeling silica and GACS system. Depicting accurate <strong>adsorption</strong>mechanisms under various conditions need to be addressed using techniques includingspectroscopic ones.Therefore, future work associated with this research should include addressing<strong>adsorption</strong> mechanisms on silica and iron oxide-coated silica under various conditionsusing techniques including XAS. Amorphous silica can be used in this regard because ofits high surface area. Speciation results can then be used to constrain surfacecomplexation modeling for <strong>adsorption</strong> to coated silica. Additionally, heavy <strong>metal</strong>distribution is regulated by microorganisms in the environment as well. Metal ions maybe involved in metabolic activities and/or sorbed to biotic coatings. This interaction isnot well understood yet and needs to be addressed for better description of naturalsystems. Models developed for biotically and/or abiotically coated heterogeneoussystems can then be incorporated into environmental management programs to predictthe bioavailability of heavy <strong>metal</strong>s and evaluate the potential ecological risk.
APPENDIX ASOLUBILITY AND SPECIATION DIAGRAM FOR NI, PB, AND ZNThe solubility and speciation diagrams of Ni, Pb, and Zn are presented below.Figure A.1 Ni solubility in open system at 298 K (in 10 -3 M NaNO3, PCO2=1 0-146 atm).159
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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),
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39generated at 45 kV and 40 mA, sca
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41PZC include electrophoretic mobil
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43Lin-edge, from 8,133 to 8,884 eV
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CHAPTER 5CHARACTERIZATION OF IRON O
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47measured by potentiometric titrat
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Table 5.2 XRD Data of Alfa Aesar (A
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51Table 5.3 XRF Results for Alfa Ae
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Figure 5.4 Particle size distributi
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55Figure 5.5 ESEM micrograph for Al
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585.2.5 Surface Charge Distribution
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Figure 5.10 Potentiometric titratio
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CHAPTER 6SYNTHESIS AND CHARACTERIZA
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Figure 6.1 Comparison between Fecon
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Figure 6.2 XRD patterns for goethit
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68iron oxide coatings at 60 °C, go
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70substrate diameter of 0.2 mm, an
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72goethite and silica results in on
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Figure 6.7 ESEM micrograph (9000x)
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76Furthermore, because discrete goe
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78Table 6.2 Surface Area and Porosi
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Figure 6.10 Surface charge distribu
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Figure 6.11 Ni adsorption</
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84that for pure silica, and the goe
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Table 7.1 Sample Preparation Condit
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Figure 7.2 EXAFS spectra of Pb/HFO
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Figure 7.3 Fourier transform and fi
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Figure 7.4 Fourier transform and fi
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Table 7.3 EXAFS Results of Pb/HFO S
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967.2 Fe XAS of Iron Oxides and Pb/
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Figure 7.7 EXAFS spectra of iron ox
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100and Venturelli, 1999). Overall t
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102(hematite, goethite, akaganeite,
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104adsorption proc
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106of pH, ionic strength, Pb loadin
Page 130 and 131: Figure 8.1 Ni adsorption</s
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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
Page 162 and 163: 140data over a broad range of condi
Page 164 and 165: 142Figure 9.8 Ni adsorption
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Page 168 and 169: Figure 10.1 Ni adsorption</
Page 170 and 171: Figure 10.2 Zn adsorption</
Page 172 and 173: Figure 10.4 Ni adsorption</
Page 174 and 175: 152one for GACS (2.77x10 -6 mole si
Page 176 and 177: Figure 10.6 Zn adsorption</
Page 178 and 179: CHAPTER 11CONCLUSIONS AND FUTURE WO
Page 182 and 183: Figure A.2 Ni speciation in 1x10 -5
Page 184 and 185: Figure A.4 Pb speciation in 5x10 -8
Page 186 and 187: Figure A.6 Zn speciation in 1x10 -5
Page 188 and 189: 166Table B.2 Potentiometric Titrati
Page 190 and 191: 168Table BA Potentiometric Titratio
Page 192 and 193: 170Table C.3 Zn Adsorption Edges on
Page 194 and 195: APPENDIX DADSORPTION STUDIES ON SIL
Page 196 and 197: 174Table D.5 Zn Adsorption Isotherm
Page 198 and 199: 176Table E.3 Pb CBC Study on 0.3 g
Page 200 and 201: APPENDIX GINTRAPARTICLE DIFFUSION M
Page 202 and 203: 180DofA = flier ^ 2fA = Exp(-fD * f
Page 204 and 205: REFERENCES1. Adamson A. W. (1982) P
Page 206 and 207: 18426. Blake R. L., Hessevick R. E.
Page 208 and 209: 18650. Combes J. M., Manceau A. and
Page 210 and 211: 18876. Elzinga E. J. and Sparks D.
Page 212 and 213: 190102. Gupta V. K. (1998) Equilibr
Page 214 and 215: 192126. Joshi A. and Chaudhuri M. (
Page 216 and 217: 194150. Liu C. and Huang P. M. (200
Page 218 and 219: 196175. Muller B. and Sigg L. (1992
Page 220 and 221: 200. Perry R. H. and Green D. W. (1
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Page 226 and 227: 204278. Villalobos M., Trotz M. A.
Page 228: 304. Zhong Z. Y., Prozorov T., Feln
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