[½»Á÷] Iron oxides in the laboratory: preparation and characterization ÒÑÓÐ10È˲ÎÓë

Iron oxides in the laboratory: preparation and characterization

×÷ÕߣºProfessor Dr. Dr. h. c. U. Schwertmann, Dr. R. M. Cornell
³ö°æÉ磺Weinheim ;New York :Wiley-VCH
³ö°æÄ꣺2000



Introduction ........................................  1
1  TheIronOxides .................................  5
1.1  The Major Iron Oxides ............................  6
1.2  Less Coinmon or Rare Iron Oxides ................... 10
1.3  Iron Oxides in the Environment ......................  13
2  General Preparative Techniques ....................  19
2.1  Quantity of Product ...............................  19
2.2  Treatment after Synthesis ...........................  19
2.2.1  Washing .................................  19
2.2.2  Drying ..................................  21
2.2.3  Storage ..................................  21
2.3  Chemical Analysis ................................  22
2.3.1  Total Analysis .............................  22
2.3.2  Extent of Isomorphous Substitution .............  23
2.3.3  Impurities ................................  23
2.4  Removal of Iron Oxides fi-om Reaction Vessels ........... 24
2.5  Purity of Reagents ................................  25
3  Methods of Characterization .......................  27
3.1  Introduction  ....................................  27
3.2  Color (A.Scheinost) ...............................  27
3.2.1  Origin of Color ............................  29
3.2.2  Color Measurement .........................  32
3.2.3  Color Systems .............................  33
3.2.4  Identification of Iron Oxides by Color and Crystal-Field Bands ...............................  37
3.3  X-Ray Powder Diffiaction ..........................  42
3.4  Microscopy .....................................  47
3.5  Surface Area. Porosity and Fractal Dimensions ........... 49
3.6   Acid Oxalate Extraction ...........................  50
3.7   Infrared Spectroscopy  .............................  51
3.8  Thermoanalysis ..................................  53
3.9   Mossbauer Spectroscopy ...........................  53
4     Synthesis Pathways ..............................  55
4.1   Nucleation and Crystal Growth ......................  55
4.1.1  Nucleation ...............................  55
4.1.2  Crystal Growth ............................  57
4.1.3  Production of Monodispersed Particles ........... 57
4.1.4  Production of Nanoparticles ................... 59
4.2   Main Routes of Synthesis ..........................  60
4.2.1  Hydrolysis of Acidic Solutions of Fe'"  Salts .......  60
4.2.2  Transformation of Ferrihydrite ................. 61
4.2.3  Oxidative Hydrolysis of Fe" Salts ...............  62
4.2.4  Phase Transformations .......................  63
4.2.5  The Gel-Sol Method ........................  63
4.2.6  Hydrothermal Precipitation ................... 64
4.2.7  Decomposition of Metal Chelates ............... 64
5    Goethite .......................................    67
5.1 Introduction   .......................................    67
5.2 Pure Goethite from Fe"'Systems ...................... 73
5.3 Pure Goethite from an Fe'ISystem  ....................  78
5.4 General Comments ...............................  83
5.5 Metal (M)-Substituted Goethites Fel-,M, OOH ........... 86
6  Lepidocrocite ...................................  93
6.1  Introduction  ....................................  93
6.2  Preparation   ....................................  94
6.3  Other Methods ..................................  97
7  Feroxyhyte .....................................  99
7.1  Introduction  ....................................  99
7.2  Preparation .....................................  99
8  Ferrihydrite ....................................  103
8.1  Introduction ....................................  103
8.2  6-Line Ferrihydrite ...............................  104
8.3  2-Line Ferrihydrite  ...............................  105
8.4  Ferrihydrites with a Range of Crystallinities ............. 110
9  AkaganCite .....................................  113
9.1  Introduction ....................................  113
(Somatoids)  ....................................  113
Solution (Rod-like Crystals) .........................  118
9.4  Si-containing Akaganeite ...........................  118
10  Hematite ......................................  121
10.1 Introduction ....................................  121
10.3 Preparation by Transformation of 2-Line Ferrihydrite  ...... 126
10.4 Monodisperse Hematites of Different Crystal Shapes ...... 129
10.5  Other Methods ..................................  132
10.6  Al-substituted Hematite ............................  133
10.7 Coated Hematite .................................  134
11  Magnetite .....................................  135
1 1.1  Introduction ....................................  135
11.2  Preparation by Oxidation of a Fe" Solution .............. 135
11.3 Cation-substituted Magnetites .......................  140
12  Maghemite .....................................  141
12.1  Introduction  ....................................  141
12.2  Preparation .....................................  141
13  GreenRusts ....................................  143
13.1  Introduction  ....................................  143
13.2  Preparation .....................................  143
14  Schwertmannite .................................  147
14.1  Introduction  ....................................  147
14.2  Preparation .....................................  148
15  Coating of SOz Sand (Quartz; Cristobalite) with Iron
Oxides ........................................  153
15.1  Introduction ....................................  153
15.2 Preparation .....................................  154
16  An Experimental Lecture for Students on the Formation
of Iron Oxides ..................................  157
16.1  Introduction ....................................  157
16.2 Demonstration: Synthesis of Iron Oxides  ............... 158
16.3 Lecture: Processes by which Iron Oxides Form ........... 159
16.4 Video : Iron in a Landscape  .........................  162
References .........................................  165
Acknowledgement ...................................  181
Index  .............................................  183