Introduction to Membrane

Transcription

1 Heinrich Strathmann Introduction to Membrane Science and Technology WILEY- VCH WILEY-VCH Verlag GmbH & Co. KG aa

2 V Preface Symbols XIII XV 1 Introduction Overview of Membrane Science and Technology History ofmembrane Science and Technology Advantages and Limitations of Membrane Processes The Membrane-Based Industry: Its Structure and Markets Future Developments in Membrane Science and Technology Biological Membranes Summary 26 Recommended Reading 26 References 27 2 Fundamentals Introduction Definition ofterms The Membrane and Its Function Membrane Materials and Membrane Structures Symmetric and Asymmetric Membranes Porous Membranes Homogeneous Dense Membranes Ion-Exchange Membranes Liquid Membranes Fixed Carrier Membranes Other Membranes Membrane Geometries Mass Transport in Membranes Membrane Separation Properties Definition ofvarious Membrane Processes Pressure-Driven Membrane Processes Activity and Concentration Gradient Driven Membrane Processes 35

3 I VI Electrical Potential and Electrochemical Potential Driven Processes Fundamentals of Mass Transport in Membranes and Membrane Processes Basic Thermodynamic Relationships with Relevance to Membrane Processes Basic Electrochemical Relationships with Relevance to Membrane Processes Electron and Ion Conductivity and Ohm's Law Ion Conductivity, Ion Mobility, and Drift Speed Coulomb's Law and the Electric Field Effect on Ions in Solution The Electric Field Effect in Electrolyte Solutions and the Debye-Huckel Theory Electrical Dipoles and Intermolecular Forces Chemical and Electrochemical Equilibrium in Membrane Systems Water Dissociation Equilibrium and the ph- and pk Values of Acids and Bases Osmotic Equilibrium, Osmotic Pressure, Osmosis, and Reverse Osmosis The Electrochemical Equilibrium and the Donnan Potential between a Membrane and a Solution The Donnan Exclusion of the Co-ions Fluxes and Driving Forces in Membrane Processes Viscous Flow through Porous Membranes Diffusion in Liquids and Dense Membranes Diffusion in Solid or Dense Materials Ion Flux and Electrical Current Diffusion of Ions in an Electrolyte Solution Ion Mobility and Ion Radius in Aqueous Solutions Migration of Ions and the Electrical Current The Transport Number and the Permselectivity of Ion-exchange Membranes Interdependence of Fluxes and Driving Forces Gas Flux through Porous Membranes, the Rnudsen and Surface Diffusion and Molecular Sieving Surface Diffusion and Capillary Condensation of Gases Mathematical Description of Mass Transport in Membranes Mass Transport Described by the Thermodynamics of Irreversible Processes Mass Transport Described by the Stefan-Maxwell Equations Membrane Mass Transport Models The Solution-Diffusion Model The Pore Flow Model and the Membrane Cut-off 84 References 87

4 VII 3 Membrane Preparation and Characterization Introduction Membrane Materials Polymeric Membrane Materials The Physical State of a Polymer Crystallinity and Glass Transition Temperature The Glass Transition Temperature and the Free Volume Molecular Weight of a Polymer Chain Macroscopic Structures of Polymers Polymer Chain Interaction and Its Effect on Physical Properties The Chemical Structure of the Polymer and Its Effect on Polymer Properties Inorganic Membrane Materials Metal Membranes Glass Membranes Carbon Membranes Metal Oxide Membranes Liquid Membrane Materials Preparation of Membranes Preparation of Symmetric Porous Membranes Isotropic Membranes Made by Sintering of Powders, Stretching of Films, and Template Leaching Membranes Made by Pressing and Sintering of Polymer Powders Membranes Made by Stretching a Polymer Film of Partial Crystallinity Membranes Made by Track-Etching Membranes Made by Micro-Lithography and Etching Techniques Glass Membranes Made by Template Leaching Porous Graphite Membranes Made by Pyrolyzing Polymer Structures Symmetric Porous Polymer Membranes Made by Phase Inversion Techniques Preparation of Asymmetric Membranes Preparation of Integral Asymmetric Membranes Practical Membrane Preparation by Phase Inversion Temperature-Induced Membrane Preparation Diffusion-Induced Membrane Preparation Phenomenological Description of the Phase Separation Process Temperature-Induced Phase Separation Process Thermodynamics of a Temperature-Induced Phase Separation of a Two-Component Mixture The Diffusion-Induced Phase Separation Process Structures of Asymmetric Membranes Obtained by Phase Inversion 136

5 VIII j Identification ofvarious Process Parameters in the Preparation of Phase Inversion Membranes General Observation Concerning the Structure of Phase Inversion Membranes The Selection of a Polymer/Solvent/Precipitant System for the Preparation of Membranes Membrane Pre- and Post-Precipitation Treatment Preparation of Composite Membranes Techniques Used for the Preparation of Polymeric Composite Membranes Preparation of Inorganic Membranes Suspension Coating and the Sol-Gel Process Perovskite Membranes Zeolite Membranes Porous Carbon Membranes Porous Glass Membranes Preparation of Homogeneous Solid Membranes Preparation of Liquid Membranes Preparation of Ion-Exchange Membranes Membrane Characterization Characterization of Porous Membranes Techniques using Microscopy 172 3,4.1.2 Determination ofmicro- and Ultrafiltration Membrane Fluxes Membrane Retention and Molecular Weight Cut-Off The Bacterial Challenge Test Membrane Pore Size Determination Air/Liquid and Liquid/Liquid Displacement The Bubble Point Method and Gas Liquid Porosimetry Liquid/Liquid Displacement Permporometry Thermoporometry Characterization of Dense Membranes Determination of Diffusivity in Dense Membranes Long-Term Stability of Membranes Determination of Electrochemical Properties of Membranes Hydraulic Permeability of Ion-Exchange Membranes The Fixed Charge Density of Ion-Exchange Membranes Determination of the Electrical Resistance of Ion-Exchange Membranes Membrane Resistance Measurements by Impedance Spectroscopy Permselectivity of Ion-Exchange Membranes Membrane Permeation Selectivity for Different Counter-ions Water Transport in Ion-Exchange Membranes Characterization of Special Property Ion-Exchange Membranes 209

6 IX The Mechanical Properties of Membranes 209 References Principles of Membrane Separation Processes Introduction The Principle ofmembrane Filtration Processes The Principle of Microfiltration The Principle of Ultrafiltration The Principle of Nanofiltration The Principle of Reverse Osmosis The Reverse Osmosis Mass Transport Described by the Solution-Diffusion Model Reverse Osmosis Transport Described by the Phenomenological Equations The Water and Salt Distribution in a Polymer Matrix and the Cluster Function The Principle ofgas and Vapor Separation Gas Separation by Knudsen Diffusion Gas Separation by Surface Diffusion and Molecular Sieving Gas Transport in a Dense Polymer Matrix The Principle of Pervaporation Material Selection for the Preparation of Pervaporation Membranes The Principle of Dialysis Mass Transport of Components Carrying No Electrical Charges in Dialysis Dialysis Mass Transport of Electrolytes Ions Dialysis of Electrolytes with Ion-Exchange in a Membrane without Fixed Membranes The Principle of Electromembrane Processes Electrodialysis and Related Processes Mass Transport in Electrodialysis Electrical Current and Ion Fluxes in Electrodialysis The Transport Number and Membrane Permselectivity Membrane Counter-Ion Permselectivity Water Transport in Electrodialysis Current Efficiency in Electrodialysis Electrodialysis with Bipolar Membranes Continuous Electrodeionization Capacitive Deionization Energy Generation by Reverse Electrodialysis Electrochemical Synthesis with Ion-Exchange Membranes Ion-Exchange Membranes in Energy Storage 4.6 The Principle ofmembrane Contactors 292 and Conversion 287

7 X Membrane Contactors Separating a Hydrophobic from a Hydrophilic Phase Membrane Contactors Used to Separate Two Immiscible Liquid Phases Membrane Contactors Separating a Liquid from a Gas Phase Membrane Distillation Osmotic Distillation Supported Liquid Membranes and Facilitated Transport Counter-Current Coupled Facilitated Transport Membrane Reactors Membrane Emulsifier Membrane-Based Controlled Release ofactive Agents 314 References Membrane Modules and Concentration Polarization Introduction Membrane Modules Membrane Holding Devices in Laboratory and Small-Scale Applications The Stirred Batch Cell The Sealed Membrane Point-of-Use Filter The Plate-and-Frame Membrane Module Industrial-Type Membrane Modules for Large Capacity Applications The Pleated Filter Membrane Cartridge The Spiral-Wound Module The Tubular Membrane Module The Capillary Membrane Module The Hollow Fiber Membrane Module Other Membrane Modules Membrane Modules Used in Electrodialysis and in Dialysis Concentration Polarization and Membrane Fouling Concentration Polarization in Filtration Processes Concentration Polarization without Solute Precipitation Concentration Polarization in Turbulent Flow Described by the Film Model Concentration Polarization in Laminar Flow Membrane Devices Rigorous Analysis of Concentration Polarization Membrane Flux Decline due to Concentration Polarization without Solute Precipitation Concentration Polarization with Solute Precipitation at the Membrane Surface Concentration Polarization in Other Membrane Separation Processes 362

8 XI Concentration Polarization in Dialysis and Electrodialysis Concentration Polarization in Electrodialysis Concentration Polarization in Gas Separation Concentration Polarization in Pervaporation Membrane Fouling and Its Causes and Consequences Prevention ofmembrane Fouling 375 References Membrane Process Design and Operation Introduction Membrane Filtration Processes Recovery Rate, Membrane Rejection, Retentate, and Filtrate Concentrations Solute Losses in Membrane Filtration Processes Operation Modes in Filtration Processes Reverse Osmosis Process Design Stages and Cascades in Membrane Filtration Ultra- and Microfiltration Process Design Ultrafiltration Process Design Diafilrration Costs ofmembrane Filtration Processes Energy Requirements in Filtration Processes Investment- and Maintenance-Related Costs in Filtration Processes Gas Separation Gas Separation Process Design and Operation Staging in Gas Separation and the Reflux Cascade Energy Consumption and Cost of Gas Separation Pervaporation Pervaporation Modes of Operation Staging and Cascades in Pervaporation Pervaporation Energy Consumption and Process Costs Dialysis Dialysis Process and System Design Dialyzer Membrane Module Constructions Process Costs in Dialysis Electrodialysis and Related Processes Process Design in Conventional Electrodialysis Operation of the Electrodialysis Stacks in a Desalination Plant Process Costs in Electrodialysis 442 References 444 Appendix A 447 Questions and Exercises 447

9 XII Appendix B 457 Index 465