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

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384.4 Extraction MethodsIn this study, the total Fe oxide concentration was determined with a modified dithionitecitratemethod based on Ross and Wang (1993), dissolving the ferric oxide via shakingsamples at ambient temperature overnight in a reducing and complexing solution of 0.68M sodium citrate solution and dithionite (sodium hydrosulfite). The supernatant was thenanalyzed with atomic absorption spectrophotometry (AA) (Ross and Wang, 1993).Amorphous Fe oxide was extracted with hydroxylamine hydrochloridehydrochloricacid solution (0.25 M NH2OH•HC1, 0.25 M HC1) following the sameprocedure as for total Fe content (Ross and Wang, 1993). The crystalline Fe oxideconcentration is the difference between the total and amorphous Fe oxide.4.5 Characterization of Uncoated and Coated SilicaStudies have shown that the <strong>adsorption</strong> of trace elements by mixed solids is related to thecontent and interaction of the component minerals; limited knowledge of the physicalchemicalcharacteristics of the system has restricted our ability to predict the distributionof trace elements in aquatic and soil environments (Meng and Letterman, 1993a). Theinformation obtained from X-ray analysis, particle size analysis, electron microscopy,surface area, and the point of zero charge are helpful in explaining <strong>adsorption</strong>.4.5.1 X-Ray Diffraction (XRD)Mineralogy was assessed with a PW3040-MPD XRD (Philips Electronic InstrumentsCompany). The silica particles were placed in the sample holder with the back fillingtechnique. Diffraction data were obtained by step-scans using Cu K-a radiation
39generated at 45 kV and 40 mA, scanning from 10 ° to 120° 20. The (hkl) valuescorresponding to various peaks were calculated and compared with the standard powderdiffraction file (PDF) (JCPDS, 1998).4.5.2 X-Ray Fluorescence (XRF)Elemental analysis was performed with a sequential X-ray spectrometer system(PW2400R, Philips Electronic Instruments Company). The PW2592/15 Rh tube andgoniometer detector were used and the X-ray path was in Helium. The results wereanalyzed with the Philips SemiQ program and were normalized to 100.0%.4.5.3 Particle Size Analysis (PSA)Particle size distribution (PSD) was evaluated with a Beckman-Coulter LS 230 analyzeras a function of ionic strength and pH. Laser diffraction technique sizes particles byutilizing the diffraction pattern of scattered light over a range of 0.04 pm to 2 mm.Sodium nitrate (NaNO3) was added to adjust the ionic strength and pH was adjusted with10-1 N sodium hydroxide (NaOH) or 10 -1 N nitric acid (HNO3). The system wascompletely mixed in a 1 L beaker with a stir bar for at least 3 hours at room temperaturebefore the particle size analysis. Reynolds number was calculated based on thecharacteristic length using the stir bar (Perry and Green, 1984).4.5.4 Scanning Electron Microscopy (SEM)Environmental scanning electron microscopy (ESEM, Model 2020, ElectroScanCorporation) and LEO 1530 field emission (FE)-SEM were utilized to study the surface
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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
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 and 56: 33existing in almost all soils and
Page 57 and 58: CHAPTER 4EXPERIMENTAL METHODSIn thi
Page 59: 37included coating temperature (T),
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
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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
Page 222 and 223:
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.
Page 228:
304. Zhong Z. Y., Prozorov T., Feln
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