Additives and crystallization processes : from fundamentals to applications / Keshra Sangwal.

Format:

Book

Author/Creator:

Sangwal, Keshra.

Language:

English

Subjects (All):

Crystal growth.

Nucleation.

Additives.

Crystallization.

Physical Description:

xvi, 451 pages : illustrations ; 25 cm

Place of Publication:

Chichester, England ; Hoboken, NJ : Wiley, [2007]

Summary:

Additives and Crystallization Processes: From Fundamentals to Applications presents a generalized description of the mechanisms of the action of additives during nucleation, growth and aggregation of crystals during various types of crystallization. Many of the topics discussed here fall in the domains of specialized fields such as industrial crystallization, crystal growth technology, and biomineralization, and are included to expose the reader to the importance of additives in crystallization processes, from a physicist's perspective, in diverse fields of basic research and applied activities such as chemical engineering, industrial crystallization, materials science, and technology of growth of crystals.

The contents of the book can be divided into four parts. The first part is introductory where basic concepts about the nature of complexes in dilute and concentrated solutions; three-dimensional nucleation and metastable zone width; and crystal growth processes are outlined. The second part consists of two chapters, and is addressed to the effect of additives on crystal growth kinetics and the observation of threshold supersaturations for growth. The third part presents an overview of processes of mineralization in natural and artificial systems and morphology and size distribution of crystals, with emphasis on the role of additives in these processes. The last part addresses applied aspects of additives in pharmaceutical, food and petroleum Industries, and processes of segregation during crystallization.

This work is primarily aimed at specialists, as well as graduate students, of industrial crystallization, chemical engineering, materials science and condensed matter physics, who are interested in looking for a comprehensive review of the fundamentals of the processes of nucleation and growth of crystals from pure systems in general and from systems containing a variety of additives in particular both in basic and applied research. In addition, it will also serve as a ready source of reference for materials scientists interested in using the basic principles of additive material interactions to design and prepare novel composite materials.

Contents:

1 Complexes in Solutions 1

1.1 Structure of Common Solvents 2

1.2 Structure of Pure Aqueous Electrolyte Solutions 4

1.2.1 Solvation of Electrolyte Ions in Solutions 4

1.2.2 Concentrated and Saturated Electrolyte Solutions 6

1.2.3 Formation of Aquo and Partially Aquo Complexes 8

1.3 Structure of Aqueous Electrolyte Solutions Containing Additives 10

1.4 Polyelectrolytes and Surfactants in Solutions 16

1.5 Polydentate Ligands and Molecular Additives 18

1.6 Crystal-Additive interactions 19

2 Three-Dimensional Nucleation and Metastable Zone Width 21

2.1 Driving Force for Phase Transition 22

2.2 Three-Dimensional Nucleation of Crystals 25

2.2.1 Three-Dimensional Nucleation Rate 25

2.2.2 Three-Dimensional Heterogeneous Nucleation 30

2.3 Metastable Zone Width 35

2.4 Nucleation and Transformation of Metastable Phases 38

2.4.1 Crystallization of Metastable Phases 38

2.4.2 Overall Crystallization 41

2.5 Induction Period for Crystallization 47

2.6 Effects of Additives 52

2.6.1 Solubility 52

2.6.2 Three-Dimensional Nucleation Rate 56

2.6.3 Metastable Zone Width 56

3 Kinetics and Mechanism of Crystal Growth: An Overview 65

3.1 Crystal Growth as a Kinetic Process 66

3.2 Types of Crystal-Medium Interfaces 67

3.3 Roughening of Steps and Surfaces 69

3.3.1 Thermodynamic Roughening and the Surface Entropy Factor 70

3.3.2 Kinetic Roughening 72

3.4 Growth Kinetics of Rough Faces 73

3.5 Growth Kinetics of Perfect Smooth Faces 75

3.6 Growth Kinetics of Imperfect Smooth Faces 78

3.6.1 Surface Diffusion and Direct Integration Models 78

3.6.2 Bulk Diffusion Models 80

3.6.3 Growth by a Group of Cooperating Screw Dislocations 82

3.6.4 Preferential Growth at Edge Dislocations 84

3.7 Effect of Foreign Substances on Growth Kinetics 85

3.7.1 Some General Considerations 87

3.7.2 Growth Kinetics by Heterogeneous Two-Dimensional Nucleation 90

3.8 Real Crystal Growth Mechanisms 96

3.8.1 Structure of Interfacial Layer 96

3.8.2 Sources of Growth Steps 100

3.9 Techniques for Studying Growth Kinetics 104

4 Effect of Impurities on Crystal Growth Kinetics 109

4.1 Mobile and Immobile Impurities 109

4.2 Surface Coverage and Adsorption Isotherms 112

4.2.1 Adsorption Isotherms 113

4.2.2 Changes in Surface Free Energy by Adsorption of Impurities 115

4.3 Kinetic Models of Impurity Adsorption 115

4.3.1 Earlier Models 115

4.3.2 Velocity of Carved Steps 116

4.3.3 Impurity Adsorption at Kinks in Steps: Kubota-Mullin Model 118

4.3.4 Impurity Adsorption at Surface Terrace: Cabrera-Vermilyea Model 119

4.3.5 Effectiveness Factor for Impurity Adsorption 121

4.3.6 Adsorption of Two Competing Impurities 124

4.4 Confrontation of Impurity Adsorption Mechanisms with Experimental Data 127

4.5 Time-Dependent Impurity Adsorption 132

4.6 Growth Kinetics in the Presence of Impurities 136

4.6.1 Basic Kinetic Equations 136

4.6.2 Time Dependence of Face Displacement 141

4.6.3 Dependence of Kinetic Coefficient for Step Motion on Impurity Concentration 142

4.7 Tapering of KDP-Type Crystals 143

4.8 Growth-Promoting Effects of Impurities 146

4.8.1 Decrease in Step Free Energy and Roughening of Steps 147

4.8.2 Formation of Surface Macroclusters 152

4.9 Impurity Adsorption on Rough Faces 157

4.10 Formation of Two-Dimensional Adsorption Layer 158

4.11 Interactions Between Additives and Crystal Interface 160

4.11.1 Nature of Impurity-Crystal Interactions 160

4.11.2 Chemical Aspects of Impurity-Crystal Interactions 166

4.12 Tailor-Made Additives 172

5 Dead Supersaturation Zone and Threshold Supersaturations for Growth 177

5.1 Origin of Threshold Supersaturations for Growth 179

5.1.1 Basic Kinetic Equations 179

5.1.2 Three Different Distances Between Impurity Particles 182

5.2 Determination of Threshold Supersaturations from v([sigma]) and R([sigma]) Data 184

5.2.1 Relationship Between the Model Involving Cooperating Spirals and the Power-Law Approach 185

5.2.2 Relationship Between the Power-Law Approach and an Empirical Expression with Corrected Supersaturation 185

5.2.3 Determination of [sigma] 186

5.3 Dependence of Threshold Supersaturations on Impurity Concentration: Basic Theoretical Equations and Linear Approximations 187

5.4 Confrontation of Theoretical Equations with Experimental Data 190

5.4.1 Impurity Adsorption at Kinks and Surface Terrace 190

5.4.2 Threshold Supersaturations and Impurity Adsorption Isotherms 193

5.5 Impurity Adsorption and Solution Supersaturation 197

5.6 Dependence of Ratios [sigma subscript d]/[sigma] and [sigma]/[sigma] on c[subscript i] 198

6 Mineralization in Natural and Artificial Systems 205

6.1 Biomineralization as a Process 205

6.1.1 Structure and Composition of Biominerals 205

6.1.2 Humans and Animals 206

6.1.3 Plants 209

6.1.4 Mollusk Shells and Avian Eggshells 211

6.2 Pathological Mineralization 216

6.3 Effect of Biologically Active Additives on Crystallization Processes 222

6.3.1 Overall Precipitation Kinetics 222

6.3.2 Overall Growth Kinetics 230

6.3.3 Phases and Polymorphs of Crystallizing Calcium Salts 242

6.3.4 Transformation of Metastable Phases 247

6.4 Scale Formation and Salt Weathering 258

7 Morphology and Size Distribution of Crystals 265

7.1 Growth Morphology of Crystals 266

7.1.1 General Concepts 266

7.1.2 Effect of Additives on Surface Morphology 273

7.1.3 Effect of Solvent on Crystal Morphology 275

7.1.4 Growth Morphodroms 276

7.2 Ostwald Ripening and Crystal Size Dispersion 282

7.3 Crystal Size Distribution 284

7.3.1 Population Balance Approach 285

7.3.2 Balanced Nucleation-Growth Approach 289

7.3.3 Approach Based on Law of Proportionate Effect 291

7.3.4 Effect of Additives on Crystal Size Distribution 295

7.4 Control of Shape and Size of Particles 298

7.4.1 Growth-Directed Synthesis 298

7.4.2 Template-Directed Synthesis 307

7.5 Biological Tissue Engineering 311

8 Additives and Crystallization Processes in Industries 319

8.1 Pharmaceutical Industry 320

8.1.1 Nucleation, Growth and Morphology of Drug Crystals 321

8.1.2 Preparation and Size Distribution of Drug Particles 324

8.2 Petroleum Industry 330

8.2.2 Crystallization Behavior of Linear Long-Chain n-Alkanes 332

8.2.3 Biodiesels and their Crystallization Behavior 338

8.3 Food Industry 348

8.3.2 Crystallization of Food Fats in the Bulk 356

8.3.3 Crystallization of Polymorphs 361

8.3.4 Crystallization of Fats and Oils in Emulsion Droplets 366

8.3.5 Number of Nucleation Centers and Overall Crystallization in Emulsion Systems 372

9 Incorporation of Impurities in Crystals 381

9.1 Types of Impurity Incorporation and the Segregation Coefficient 382

9.2 Equilibrium Segregation Coefficient 386

9.2.1 Binary Mixture Approach 386

9.2.2 Thermodynamic Approach 388

9.2.3 Theoretical Predictions and their Comparison with Experimental Data on Segregation Coefficient 389

9.3 Effective Segregation Coefficient 396

9.3.1 Volume Diffusion Model 396

9.3.2 Diffusional Relaxation Approach 397

9.3.3 Statistical Selection Approach 401

9.3.4 Surface Adsorption Approach 402

9.4 Relationship Between Effective Segregation Coefficient and Face Growth Rate 410

9.5 Threshold Supersaturation for Trapping of Impurities During Growth 413

9.6 Effective Segregation Coefficient and Internal Stresses Caused by Impurities 416.

Notes:

Includes bibliographical references and indexes.

ISBN:

9780470061534

0470061537

OCLC:

122715442

Online:

Publisher description