MEMBRANE SEPARATION PROCESSES. PHI Learning PnfaO Mmfei. Kaushik Nath. Professor and Head

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1 MEMBRANE SEPARATION PROCESSES 1 1 %%^\^imte!#as#l=a^ Kaushik Nath Professor and Head Chemical Engineering Department GH Patel College of Engineering and Technology Vallabh Vidyanagar, Gujarat PHI Learning PnfaO Mmfei GBBr New Delhi

2 Contents Preface XI 1 Overview of Membrane Separation Processes Equilibrium and Rate Governed Separation What is a Membrane Basic Principle of Membrane Separation Historical Development of Membranes Classification of Membrane Processes Advantages of Membrane Processes Disadvantages Major Areas of Application Chemicallndustry Pharmaceutical Industry Food and Dairy Industry Biotechnology Industry Future Prospects i4 Questions 15 2 Membrane Types, Materials, Preparation and Characterization Types of Synthetic Membranes Microporous Membranes Asymmetric Membrane Thin Film Composite Electrically Charged Inorganic Membrane Membrane Modules Typical Flow Patterns Membrane Materials Pore Characteristics General Methods of Membrane Manufacture Phase Inversion Process 35 iii

3 iv Contents Track-etch Method Sol-gel Peptisation Method Interfacial Polymerization Melt Pressing Film Stretching Template Leaching Preparation of Ion-exchange Membranes Measurement of Pore Size and Solute Rejection Properties Visualization Methods Hydraulic Permeability Bubble Pressure or Point (Also Gas-Liquid Porosimetry) A Liquid Displacement (Also Liquid-Liquid Porosimetry) Hg Porosimetry Gas-Liquid Diffusion Permporometry Gas Adsorption-Desorption (Also BET Method) Thermoporometry Molecular Weight Cut Off (MWCO) Microbial Challenge Test Measurement and Interpretation of Surface Properties 48 Short Questions and Problems 49 3 Reverse Osmosis Concept of Osmosis Determination of Osmotic Pressure Thermodynamic Consideration of Osmosis Isotonic Solution The Phenomenon of Reverse Osmosis Pressure Requirement High Pressure and Low Pressure RO Advantages of Reverse Osmosis Membrane Materials and Modules Selection Criteria of RO Membrane Models for Reverse Osmosis Transport Kedem-Katchalsky Model Spiegler-Kedem Model Solution-Diffusion (SD) Model Pore Transport Model Modified Solution-Diffusion Model Design and Operating Parameters Concentration Polarization Cake Enhanced Concentration Polarization (CECP) 73

4 Contents v 3.6 Membrane Plugging Equivalent Work Requirement Design of an RO Module Reverse Osmosis for Non-aqueous System Osmotic Pinch Effect Forward Osmosis Applications 80 Notations 83 Short Questions 84 Problems 86 Nanofiltration Principle of Nanofiltration Nanofiltration Membranes Transport Mechanism in NF Membranes Transport Mechanism of Charged Solutes Parameters Affecting the Performance of NF Membranes Mass Transfer in Nanofiltration Fouling 4.4 Process Limitations 96 Model Industrial Applications 97 Notations 99 Short Questions Ultrafiltration Basic Principle of Ultrafiltration Advantages of Ultrafiltration Ultrafiltration vis-a-vis Conventional Filtration Ultrafiltration Membranes Membrane Modules Membrane Characterization Configuration of UF Unit Types of Devices in Ultrafiltration Funnel In-line Filters Centrifuge Tube Devices Diffusion Devices Stirred Cell Modules Cross Flow Modules Factors Affecting the Performance of Ultrafiltration Flux Equation for Ultrafiltration 110

5 VI Contents 5.7 Models for Solvent Flux Resistance Model Gel Polarization Model Fouling and Flux Decline Methods to Reduce Concentration Polarization Energy Considerations Micellar-enhanced Ultrafiltration Affinity Ultrafiltration Affinity Ultrafiltration in Protein Purification Applications 123 Notations 126 Short Questions 127 Problems Mlcroflltration Basic Principle of Microfiltration Cross Flow Microfiltration Dead-end Microfiltration Microfiltration Membranes Membrane Pore Configuration Mechanism of Transport Retention Characteristics Flow Characteristics Membrane Plugging and Throughput Fouling in Microfiltration Membranes External Fouling 141 _' Internal Fouling Theoretical Models for Membrane Fouling A Factors Affecting Membrane Fouling Control of Fouling Membrane Cleaning Energy Consideration Applications 146 Short Questions and Problems Dialysis Principle of Dialysis Dialysis Systems Dialysis Membranes Mass Transfer in Dialysis Applications Hemodialysis Removal of Alcohol From Beer to Produce a Reduced Alcohol Beer Other Applications of Dialysis 159

6 Contents vii 7.6 Diffusion Dialysis Advantages of Diffusion Dialysis Application of Diffusion Dialysis 163 Notations 163 Short Questions 163 Problems 164 Gas Separation Basic Principle Membranes for Gas Separation Membrane Modules Fundamental Mechanism of Gas Transport Knudsen Diffusion Molecular Sieving Solution-Diffusion Dual Sorption Model Facilitated Transport Microscopic Models Factors Affecting Gas Permeation Temperature Pressure Plasticization Permeant Condensability Polymer Crystallinity Complete Mixing Model Solution of Equations Equations for Multicomponent Mixtures Cross Flow Model Counter Current Model Applications 192 Notations 195 Short Questions 196 Problems 197 Pervaporation Basic Principle Advantages of Pervaporation Membrane Characteristics Mass Transfer in Pervaporation Permeation Through the Membrane Thermodynamic Considerations Design of a Pervaporation Module Concentration Polarization Factors Affecting Pervaporation 211

7 viii Contents 9.9 Temperature Drop at the Membrane Interface Applications 213 Notations 217 Short Questions and Problems Ion Exchange Membrane Process: Electrodialysis Basic Principle Ion Exchange Membranes Ion Exchange Membranes in Chlor-Alkali Cells Homogeneous and Heterogeneous Membranes Bipolar Membrane Permselectivity Energy Requirement, Current Utilization, Efficiency Concentration Polarization and Limiting Current Density Other Operating Parameters Batch and Continuous Electrodialysis Electrodialysis Reversal (EDR) Electrodeionization (EDI) Working Principle Advantages and Disadvantages of EDI Applications of Electrodialysis 235 Short Questions 237 Problems Introduction to Liquid Membrane 11.1 Benefits of Liquid Membranes Types of Liquid Membranes Bulk Liquid Membranes Emulsion Liquid Membranes (ELM) Thin Sheet Supported Liquid Membranes Hollow Fibre Supported Liquid Membranes Polymer Inclusion Membrane Mechanism of Mass Transfer in Liquid Membranes Simple Permeation Mechanism Facilitated Transport Mechanism Applications 248 Short Questions Facilitated Transport Mechanism of Facilitated Transport Coupled Transport Carrier Agent Competitive Facilitated Transport with Two Permeants and One Carrier 257

8 Contents IX 12.3 Active and Passive Transport Symport and Antiport Some Potential Applications of Facilitated Transport 263 Short Questions and Problems Other Membrane Processes Membrane Contactor Advantages and Disadvantages Principle of Operation Applications Membrane Distillation Mechanism Membrane Reactors Membrane Bioreactors Membrane Recycle Bioreactor Plug Flow Bioreactor Charge Mosaic Membranes Piezodialysis Perstraction Flux and Separation 13.7 Membrane Chromatography 280 in Perstraction PEM Hydrogen Fuel Cell Integration of Membrane and Non-membrane Processes 283 Short. Questions Biomedical Applications of Membranes Blood Oxygenator Controlled Drug Delivery Controlled Release Mechanisms Polymers Used in Controlled Release Application of Controlled Release Plasmapheresis Membranes in Bioartificial Organs 293 Short Questions 295 Appendix References and Further Reading Index