THE COLLOID CHEMISTRY OF SILICA AND SILICATESPDF电子书下载

CHAPTER Ⅰ THE SILICA-WATER SYSTEM 3

1．Silica—General Occurrence 3

2．Solubility of Silica 4

2a．Various Modifications of Silica 4

2b．Relation between Particle Size and Solubility 8

2c．The Nature of Soluble Silica;Effect of pH 11

3．Rate of Dissolution of Silica 13

3a．Mechanism of Dissolution 13

3b．Effect of Particle Size 14

3c．Effect of Impurities 14

4．Deposition of Silica from Solution 15

References 16

CHAPTER Ⅱ THE SOLUBLE SILICATES 18

1．Introduction 18

2．Formation of Silicate Ions in Aqueous Solution 18

3．Soluble Silicate Glasses 19

4．Polymerization-Depolymerization Phenomena in Aqueous Silicate Solutions 20

4a．Formation of Polysilicate Ions 21

4b．Structure of Polysilicate Ions 24

4c．Equilibrium:Polymerization vs．Depolymerization 24

4d．Molecular Weight of Sodium Silicate in Aqueous Solution 26

4e．Polymerization Due to Added Salts 28

5．Crystalline Alkali Metal Silicates 28

5a．Orthosilicates 28

5b．Metasilicates 29

5c．Disilicates 30

5d．Polysilicates 30

6．Other Soluble Silicates 30

6a．Quaternary Ammonium Silicates 30

6b．Silicates of Werner Complex Bases 31

6c．Silicon in Complex Anions 31

7．Effect of Electrolytes and Organic Solvents on Soluble Silicates 31

7a．Effect of Alkali Metal Salts 31

7b．Water-miscible Organic Solvents 32

References 32

CHAPTER Ⅲ THE CHEMISTRY OF SILICIC ACID 34

1．Preparation of Monosilicic Acid 34

1a．Solution Saturated with Respect to Amorphous Silica 34

1b．Hydrolysis of Monomeric Silicon Compounds 35

1c．Reaction of Monomeric Metal Silicates with Acids 35

2．Polymerization of Silicic Acid 36

2a．Mechanism of Formation of Siloxane Bonds 36

2b．Formation of Colloidal Silica and Polysilicic Acids 38

2c．Polymerization of Silicic Acid in Acidic vs．Basic Solution 41

2d．Formation of Gel 43

2e．Structure of Primary Particles in Gel 44

2f．General Summary of Polymerization and Aggregation 44

3．Factors Affecting Rate of Polymerization of Silicic Acid to Form Gel 45

3a．Effects of pH and Impurities 45

3b．Mechanism of Catalyzed Reaction in Acidic Solution 48

3c．Concentration of Silica 54

3d．Effect of Water-miscible Organic Solvents 55

4．Properties of Soluble Polysilicic Acids 55

4a．Physical Characteristics 55

4b．Acid Strength 56

4e．Heat of Polymerization 57

5．Reactions of Polysilicic Acid 58

5a．Complexes Formed with Polar Organic Compounds 58

5b．Combination with Organic Polymers 67

5c．Reaction with Metal Ions 68

References 69

CHAPTER Ⅳ ESTERS OF SILICIC AND POLYSILICIC ACID 72

1．Introduction 72

2．Hydrolysis of Esters to Silicic and Polysilicic Acid 73

3．Practical Aspects of Silicic Esters 75

4．Esters of Polysilicic Acid Prepared by the Hydrolysis and Con-densation of Alkoxychlorosilanes 77

5．Esterification of Polysilicic Acid 80

6．Polymeric Silicic Esters Linked through Carbon 84

7．Summary of Siloxane Polymer Structures 84

References 85

CHAPTER Ⅴ COLLOIDAL SILICA 87

1．Definition 87

2．Polysilicic Acids and Colloidal Silica 87

3．Recent Developments 89

4．Methods of Preparing Aqueous Sols 90

4a．Dialysis 90

4b．Electrodialysis 90

4c．Dissolution of Elemental Silicon 90

4d．Sols by Reaction of Acid with Sodium Silicate 91

4e．Peptizing Gels at Elevated Temperature 92

4f．Ion Exchange 93

5．Nature of the Particles 95

5a．Amorphous Nature 95

5b．Degree of Aggregation;Effect on Viscosity 96

5c．Degree of Hydration 98

6．Particle Size and Shape 100

6a．Measurement by the Electron Microscope 101

6b．Methods of Determining Specific Surface Area 103

6c．Comparison of Methods 105

7．Ionic Charge on the Particles 106

7a．Effect of pH 106

7b．Effect of Electrolytes 108

7c．Effect of Organic Solvents 110

7d．Types of Counter Ions 110

7e．Water-soluble Colloidal Silica Powder 112

8．Stability of Colloidal Silica—Gelling Mechanism 113

9．Products and Applications 114

9a．Commercial Products 114

9b．Uses of Aqueous Sols 114

10．Organosols 120

10a．Preparation 120

10b．Uses 121

References 122

CHAPTER Ⅵ AMORPHOUS SILICA GELS AND POWDERS 127

1．Introduction 127

2．Structure of Silica Gel 129

2a．Size and Shape of Primary Particles 130

2b．Density of Packing of Primary Particles 130

2c．Nature of the Bond between Particles 132

2d．Range of Structure 133

3．Characterization of Silica Gels and Powders 134

3a．Size and Shape of Primary Particles;Specific Surface Area 134

3b．Density of Packing of Primary Particles;Porosity 135

3c．Coalescence;Interparticle Bonding 137

3d．Other Methods 137

4．Methods of Preparing and Drying Xerogels 137

4a．Preparation from Soluble Silicates and Acids 139

4b．Gels from Colloidal Silica 140

4c．Dehydration of Silica Gels 140

5．Adsorptive Properties of Silica Gels 144

5a．Capillary Condensation and Monolayer Adsorption 144

5b．Pore Volumes;Micropores and Macropores 145

5c．Adsorption Hysteresis 148

5d．Adsorbates 148

5e．Specific Adsorbents 150

6．Miscellaneous Gel Structures 152

6a．Aerogels 152

6b．Definite Silica Hydrates 154

6c．Porous Silica Gels from Glasses 156

7．Fine Silica Powders 157

7a．Particle Size and Aggregation 157

7b．Preparation by Precipitation from Aqueous Solution 159

7c．Condensation from SiO2 Vapor 168

8．Hydrophobic Silica Gels and Powders 169

9．Products and Uses 174

References 175

CHAPTER Ⅶ COLLOIDAL SILICATES 181

1．Introduction 181

2．Amorphous Insoluble Silicates 181

2a．Formation from Soluble Silicates and Metal Salts 181

2b．Aluminosilicates 184

3．Microporous Crystalline Zeolites 186

3a．Adsorption of Gases 186

3b．Cation Exchange in Microporous Silicates 189

4．Sheetlike Crystalline Silicates of Colloidal Thickness 190

4a．The Montmorillonite Minerals 191

4b．The Mica Group;Mechanically Dispersible Colloids 198

4c．The Kaolin Group 202

5．Rodlike and Fiberlike Crystalline Silicates of Colloidal Thickness 206

5a．Tubular Fibers 206

5b．Lathlike Fibers 212

5c．Other Fibrous Minerals 215

6．Plasticity of Clays and Soils 217

6a．Plasticity 217

6b．Soil Conditioning 219

7．Organic Modifications of Colloidal Silicates 220

7a．Nonionic Polar Organic Compounds 221

7b．Cationic Organic Compounds 223

7c．Anionic Organic Compounds 226

7d．Other Procedures 227

References 228

CHAPTER Ⅷ SURFACE CHEMISTRY OF SILICA AND SILICATES 233

1．Introduction 233

2．The Silanol Surface of Amorphous Silica 234

2a．Composition and Dehydration 234

2b．Effect of Dehydration of the Surface on Adsorption of Polar Molecules 238

2c．Heat of Wetting by Water 240

2d．The Geometry of the Silanol Surface;Hydroxyl Groups per Square Millimicron 242

3．Adsorption of Inorganic Ions 247

3a．Adsorption of Hydroxyl Ions 247

3b．Adsorption of Metal Ions 249

3c．Polarization of Metal Ions 250

4．The Adsorption of Nonionic Organic Compounds 251

4a．Adsorption of Organic Compounds from the Gas Phase 253

4b．Adsorption from Solution 254

4c．Organic-coated Aerogel 254

5．Chemically Bound Coatings 255

5a．Halides 255

5b．Adsorption of Organic Cations 255

5c．Adsorption of Soaps and Complexes of Aliphatic Acids 256

5d．Organosilicon Compounds 257

5e．Reaction of Alcohols with the Silica Surface;Estersils 257

6．The Surface of Quartz 258

7．The Surface of Crystalline Aluminosilicates 259

8．The Surface of Amorphous Aluminosilicate Cracking Catalysts 261

8a．Acidity and Catalytic Activity 262

8b．Nature of the Acid Sites 263

8c．Lability of the Aluminosilicate Structure 265

8d．Water Content and Catalytic Activity 266

8e．Poisoning the Surface 267

9．Sintering of Silica Gels 269

References 272

CHAPTER Ⅸ SILICA IN LIVING ORGANISMS 276

1．Introduction 276

1a．Silicates and the Origin of Life 276

1b．Role of Organic Matter in the Decomposition of Mineral Silicates 278

1c．Detection of Silica in Organic Matter 279

2．Occurrence in Lower Organisms 280

3．Occurrence in Plants 282

3a．Silicon Requirement in Plants 282

3b．Effect on Soil Fertility 283

3c．Effect on Resistance of Plants to Disease 284

3d．Occurrence of Silica in Plant Tissues 286

3e．Mechanism of Entry of Silica into Plants and the Com-pounds Formed 289

3f．Silicification of Wood and Plant Tissues 291

4．Occurrence of Silica in Animals 293

4a．Significance 293

4b．Quantities Found 294

4c．Formation of Organic-Silica Complexes 294

5．Silica Gel as a Culture Medium 296

6．Conclusion 296

References 297

AUTHOR INDEX 301

SUBJECT INDEX 310