The Role of Structural Iron Oxidation in the Weathering of Trioctahedral Micas by Aqueous Solutions
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Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1988 The oler of structural iron oxidation in the weathering of trioctahedral micas by aqueous solutions James Edward Amonette Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Agricultural Science Commons, Agriculture Commons, and the Agronomy and Crop Sciences Commons Recommended Citation Amonette, James Edward, "The or le of structural iron oxidation in the weathering of trioctahedral micas by aqueous solutions " (1988). Retrospective Theses and Dissertations. 9322. https://lib.dr.iastate.edu/rtd/9322 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. 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Photographs included in the original manuscript have been reproduced xerographically in this copy. 35 mm slides or 6" X 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. Accessing the UMIWorld's Information since 1938 300 North Zeeb Road, Ann Arbor, Ml 48106-1346 USA Order Number 8825872 The role of structural iron oxidation in the weathering of trioctahedral micas by aqueous solutions Amonette, James Edward, Ph.D. Iowa State University, 1988 UMI 300N.ZeebRd. Ann Aibor, MI 48106 The role of structural Iron oxidation in the weathering of trioctahedral micas by aqueous solutions by James Edward Amonette A Dissertation Submitted to the Graduate Faculty in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY Department: Agronomy Major: Soil Chemistry Approved : Signature was redacted for privacy. In Charge of Major Work Signature was redacted for privacy. Forthe Major Department Signature was redacted for privacy. For the Graduate College Iowa State University Ames, Iowa 1988 il TABLE OF CONTENTS PAGE CHAPTER I. GENERAL INTRODUCTION 1 CHAPTER II. AN IMPROVED SEMI-MICRO METHOD FOR THE DETERMINATION OF FERROUS IRON IN NON-REFRACTORY SILICATE MINERALS 8 Introduction 8 Survey of existing methods 8 Choice of method 12 Experimental 14 Reagents 14 Apparatus 15 Mineral samples 16 Methods 17 Results and Discussion 17 Standardization of reagents 18 Modifications to the assay procedure ....... 25 Interferences and corrections 32 Recommended method 44 Conclusions 48 CHAPTER III. THE ESTIMATION OF OCTAHEDRAL AND TETRAHEDRAL CATION SHEET OCCUPANCIES IN TRIOCTAHEDRAL MICAS BY AN X-RAY DIFFRACTION TECHNIQUE 50 Introduction 50 Theoretical Aspects . 53 Experimental 57 Mica samples 57 Di ffractometers 58 Effective x-ray thickness 59 Observed structure factors 61 Theoretical structure factors 61 Structural formulas 63 iii Results and Discussion 64 Fractional coordinates 64 Sensitivity of OOA reflections 67 Observed data 71 Cation site occupancies 77 Summary and Conclusions 90 CHAPTER IV. OXIDATIVE WEATHERING OF TRIOCTAHEDRAL MICAS BY BUFFERED HgOg SOLUTIONS—1. OXIDATION AND THE KINETICS OF DISSOLUTION 92 Introduction 92 Experimental 94 Micas 94 Weathering solutions 95 Apparatus 97 Experimental design 100 Effluent analyses 102 Kinetic model 103 Results and Discussion 105 Oxidation 105 Dissolution 112 Kinetics of dissolution 121 Conclusions 132 CHAPTER V. OXIDATIVE WEATHERING OF TRIOCTAHEDRAL MICAS BY BUFFERED HgOg S0LUTI0NS--2. STRUCTURAL ALTERATIONS 134 Introduction 134 Experimental 141 Micas 141 MBssbauer analyses 141 X-ray diffraction analyses 143 Infrared spectroscopic analyses 143 Results and Discussion 144 MBssbauer spectra 144 X-ray diffraction analyses 156 Infrared spectra ..... 166 Summary and Conclusions 178 iv CHAPTER VI. OXIDATIVE WEATHERING OF TRIOCTAHEDRAL MICAS BY BUFFERED HgOg SOLUTIONS-3. K-DEPLETED AND DEUTERATED SAMPLES 180 Introduction ......... 180 Experimental 183 Micas and apparatus 183 K-depletion and deuteration 184 Weathering treatments 185 Analytical techniques 186 Results and Discussion 187 Chemical analyses 187 Infrared spectra 193 X-ray diffraction data 204 Effluent analyses 210 Summary and Conclusions 213 CHAPTER VII. SUMMARY 216 ACKNOWLEDGEMENTS 225 LITERATURE CITED 227 APPENDIX—DEVELOPMENT OF KINETIC MODEL FOR DISSOLUTION OF MICA PARTICLES 235 V LIST OF FIGURES PAGE FIGURE II-l. Apparent normality of a V(V) solution when standardized against FES in 6C-ml solutions containing different amounts of a 2 M H2S0^-1.2 M HgPO^ mixture 21 FIGURE II-2. Fe(II) values, expressed as a percentage of "initial values", that were obtained by the modified gravimetric method when lepidomelane and FES samples were digested at various temperatures and for various time periods .... 31 FIGURE II-3. Fe(II) values, expressed as a percentage of the "best values", that were obtained by the modified gravimetric method when lepidomelane and muscovite samples were digested at 60°C for various time periods 34 FIGURE II-4. Fe(II) values obtained by the modified gravimetric method when FES samples were digested at 60°C for various time periods in the presence of 0 to 5 mmol of Al(OH)g . 38 FIGURE II-5. Fe(II) values obtained by the modified gravimetric method when FES samples were digested at 60°C for 24 hours in the presence of various quantities of Al(OH)g, MgO and SiOg'O.THgO 40 FIGURE III-l. X-ray diffraction patterns showing the 004 and 005 reflections of five trioctahedral micas (Mo^^ radiation) . 73 FIGURE III-2. Relationship between the observed 'FiQQ^yQQg ratios for six trioctahedral micas and the effective Fe(II) v1 occupancy of the octahedral sheet, and the limits to this relationship that were calculated for a representative mica assuming the complete substitution of F for structural OH and of Fe(III) for tetrahedral A1 76 FIGURE III-3. The observed IFI004/Q05 ratios for six trioctahedral micas and the range of theoretical |f^loo4/o05 ratios that were calculated for each mica assuming various octahedral and tetrahedral cation site occupancies, expressed in terms of the effective Fe(II) occupancy of the octahedral sheet [the Fe(II) ocupancy associated with the conventional cation site assignment and that predicted by the observed ÎFÎ004/005 ratio are shown by the solid symbols] 89b FIGURE IV-1. Schematic of a reaction vessel used to weather micas by the continuous-flow method 99 FIGURE IV-2. Concentrations of HgOg measured in the effluent during treatments of 1300-mg mica samples by 25% HgOg-l M KOAc-0.1 M KgEDTA solutions at 80°C 107 FIGURE IV-3. Content of Fe(III) in 1300-mg mica samples after treatment for various periods by 25% HgOg-l M KOAc-0.1 M KgEDTA solutions at 80°C Ill FIGURE IV-4. Cumulative amounts of A1 measured in the effluent during treatments of 1300-mg mica samples by the matrix (1 M KOAc-0.1 M KgEDTA) and HgOg (25% HgOg + matrix) solutions at 80°C 114 FIGURE IV-5. Cumulative amounts of Mg measured in the effluent during treatments of 1300-mg mica samples by the matrix (1 M KOAc-O.l M KgEDTA) and HgOg {25% HgOg + matrix) vii solutions at 80*C 116 FIGURE IV-6. Cumulative amounts of Fe measured in the effluent during treatments of 1300-mg mica samples by the matrix (1 M KOAc-0.1 M KgEDTA) and HgOg (25% HgOg + matrix) solutions at 80*C 118 FIGURE V-1. MOssbauer spectra recorded at nominal liquid nitrogen temperature (77 K) for samples of untreated biotite or biotite that was treated with the HgOg weathering solution for 36 days 146 FIGURE V-2. MBssbauer spectra recorded at nominal liquid nitrogen temperature (77 K) for samples of untreated siderophyllite or siderophyllite that was treated with the HgOg weathering solution for 36 days 151 FIGURE V-3. MBssbauer spectra recorded at room temperature (298 K) for samples of untreated biotite or biotite that was treated for 1, 2, 4, 6, or 12 days with the HgOg weathering solution 154 FIGURE V-4. X-ray diffractograras (Mo^^ radiation) of untreated phlogopite (U), and of phlogopite that was treated for 36 days with the matrix (M36) or HgOg (H36) weathering solutions 158 FIGURE V-5. X-ray diffractograms (Mo^^ radiation) of untreated biotite (U), of biotite that was treated for 36 days with the matrix weathering solution (M36), and of biotite that was treated for 2, 4, 6, or 36 days with the HgOg weathering solution (H2, H4, H6, H36) 160 viii FIGURE V-6. X-ray diffractograms (MOj^ radiation) of untreated siderophyllite (U), and of siderophyllite that was treated for 36 days with the matrix (M36) or HgOg (H36) weathering solutions 162 FIGURE V-7. Infrared spectra of untreated phlogopite (U), and of phlogopite that was treated for 36 days with the HgOg weathering solution (H36) 168 FIGURE V-8. Infrared spectra of untreated biotite (U), and of biotite that was treated for 36 days with the HgOg weathering solution (H36) 170 FIGURE V-9.