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

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34pH range of 4 to 7. <strong>Heavy</strong> <strong>metal</strong>s may exist at trace level in natural aquatic systems (10-11-10-7 M, Buerge-Weirich et al. 2002; Nolan et al. 2002) and may be at much higherconcentrations in industrial wastewater discharge and contanimated sites. To developmodels that can be widely applicable, <strong>adsorption</strong> data will be collected over as broad a<strong>metal</strong> concentration range as possible from approximately 10 -11 M up to less than itssolubility limit.In the following chapters, methods to achieve the objectives and correspondingresults are presented.
CHAPTER 4EXPERIMENTAL METHODSIn this section, methods used for synthesis, characterization, <strong>adsorption</strong>, XAS, andmodeling are presented. All chemicals used are of reagent grade unless otherwise stated.Quality assurance / quality control (QA/QC) was conducted in accordance with standardmethods (Clesceri et al. 1998) and the associated procedure is presented in Appendix A.For all experiments, Milli-Q Type 1 deionized (DI) water was used; all containers werewashed, soaked in 10% HNO3 overnight, and then rinsed with DI water before use.4.1 Synthesis of Iron OxidesAmorphous hydrous ferric oxide (HFO) used in this study was synthesized following themethod described by Dzombak and Morel (1986). HFO was always freshly synthesizedfor each <strong>adsorption</strong> study in a 1 g L-1 batch using Fe(NO3)3.9H2O (99.99%+, Aldrich) andDI water. Precipitation was conducted under a N2 environment (N2 flowrate = 1-2 Lmin-1 , N2 pressure = 2.27 atm) and turbulence (Re .1.0x104) maintained by a motorizedstirrer with polyethylene coated impeller. The ferric nitrate solution was adjusted to pH7-7.5 by dropwise addition of 10 N NaOH solution and aged for 4 hours before<strong>adsorption</strong> studies.Goethite was synthesized based on the Atkinson et al. (1967) method andcharacterized in earlier work (Trivedi and Axe, 2001b); its characteristics are discussedalong with that of the coating in Chapter 5 and 6. The procedure is similar to that forHFO except that the ferric nitrate solution was adjusted to pH 12. After aging for 435
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Copyright Warning & RestrictionsThe
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ABSTRACTHEAVY METAL ADSORPTION ON I
Page 5 and 6: HEAVY METAL ADSORPTION ON IRON OXID
Page 7 and 8: APPROVAL PAGEHEAVY METAL ADSORPTION
Page 9 and 10: Fan, M.; Boonfueng, T.; Xu, Y.; Axe
Page 11 and 12: ACKNOWLEDGMENTI would like to expre
Page 13 and 14: TABLE OF CONTENTS(Continued)Chapter
Page 15 and 16: TABLE OF CONTENTS(Continued)Chapter
Page 17 and 18: LIST OF TABLES(Continued)TablePageB
Page 19 and 20: LIST OF FIGURES(Continued)FigurePag
Page 21 and 22: LIST OF FIGURES(Continued)FigurePag
Page 23 and 24: CHAPTER 1INTRODUCTIONHeavy<
Page 25 and 26: 3and Sigg, 1992; Gunneriusson et al
Page 27 and 28: CHAPTER 2OXIDES AND THEIR EFFECT ON
Page 29 and 30: 7et al. 1996; Green-Pedersen et al.
Page 31 and 32: 9identify components, distribution,
Page 33 and 34: 11oxides. Because extraction method
Page 35 and 36: 13Table 2.2 Some Coating Work and C
Page 37 and 38: 15increasing the sorbate concentrat
Page 39 and 40: 17mole Cu g-1 goethite (-1-7% of th
Page 41 and 42: 19Overall, macroscopic adso
Page 43 and 44: 21hematite (up to 9.9 limo' Pb ril-
Page 45 and 46: 23concentration in their system was
Page 47 and 48: 25Surface complexation modeling (SC
Page 49 and 50: 27Overall, surface complexation mod
Page 51 and 52: 29Spectroscopic techniques, especia
Page 53 and 54: 31• Understand the effect of comp
Page 55: 33existing in almost all soils and
Page 59 and 60: 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</
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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
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Figure 8.1 Ni adsorption</s
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110high metal load
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Figure 8.3 x(k)•k3 spectra and Fo
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Figure 8.4 (k)•k3 spectra of Ni-H
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Figure 8.5 Fourier transforms (magn
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118be fit using either Fe or Ni ato
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1208.3 EXAFS Analysis of FeThe x(k)
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Table 8.4 EXAFS Results of HFO and
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CHAPTER 9SURFACE COMPLEXATION MODEL
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Figure 9.1 Potentiometric titration
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128Table 9.1 Surface Reactions and
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132Table 9.2 Model Parameters for N
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1369.3 Zn Adsorption on GoethiteReg
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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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