Membrane Gas Separation

Total Page:16

File Type:pdf, Size:1020Kb

Membrane Gas Separation Membrane Gas Separation Membrane Gas Separation YURI YAMPOLSKII A.V. Topchiev Institute of Petrochemical Synthesis, Moscow, Russia BENNY FREEMAN University of Texas at Austin, Austin, TX, USA A John Wiley & Sons, Ltd., Publication This edition fi rst published 2010 © (2010) John Wiley & Sons Ltd Registered offi ce John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, United Kingdom For details of our global editorial offi ces, for customer services and for information about how to apply for permission to reuse the copyright material in this book please see our website at www.wiley.com. The right of the author to be identifi ed as the author of this work has been asserted in accordance with the Copyright, Designs and Patents Act 1988. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books. Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book. This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold on the understanding that the publisher is not engaged in rendering professional services. If professional advice or other expert assistance is required, the services of a competent professional should be sought. The publisher and the author make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifi cally disclaim all warranties, including without limitation any implied warranties of fi tness for a particular purpose. This work is sold with the understanding that the publisher is not engaged in rendering professional services. The advice and strategies contained herein may not be suitable for every situation. In view of ongoing research, equipment modifi cations, changes in governmental regulations, and the constant fl ow of information relating to the use of experimental reagents, equipment, and devices, the reader is urged to review and evaluate the information provided in the package insert or instructions for each chemical, piece of equipment, reagent, or device for, among other things, any changes in the instructions or indication of usage and for added warnings and precautions. The fact that an organization or Website is referred to in this work as a citation and/or a potential source of further information does not mean that the author or the publisher endorses the information the organization or Website may provide or recommendations it may make. Further, readers should be aware that Internet Websites listed in this work may have changed or disappeared between when this work was written and when it is read. No warranty may be created or extended by any promotional statements for this work. Neither the publisher nor the author shall be liable for any damages arising herefrom. Library of Congress Cataloging-in-Publication Data Yampolskii, Yuri Membrane gas separation / Yuri Yampolskii and Benny Freeman. p. cm. Includes bibliographical references and index. ISBN 978-0-470-74621-9 (cloth) 1. Gas separation membranes. 2. Polyamide membranes. 3. Gases–Separation. I. Yampolskii, Y. P. (Yuri Pavlovich) II. Title. TP248.25.M46F74 2010 660′.043–dc22 2010013153 A catalogue record for this book is available from the British Library. ISBN: HB: 9780470746219 Set in 10/12 pt Times by Toppan Best-set Premedia Limited. Printed and bound in Singapore by Markono Print Media Pte Ltd. Contents Preface xiii Contributors xvii I. Novel Membrane Materials and Transport in Them 1 1 Synthesis and Gas Permeability of Hyperbranched and Cross-linked Polyimide Membranes 3 Shinji Kanehashi, Shuichi Sato and Kazukiyo Nagai 1.1 Introduction 3 1.2 Molecular Designs for Membranes 6 1.3 Synthesis of Hyperbranched Polyimides 7 1.3.1 Amorphous Cross-linked Polyimides (Type II) 7 1.3.2 Hyperbranched Polyimides (Type III) 9 1.4 Gas Permeation Properties 13 1.4.1 Amorphous Cross-linked Polyimides (Type II) 13 1.4.2 Hyperbranched Polyimides (Type III) 17 1.4.3 Selectivity and Permeability 21 1.5 Concluding Remarks 21 References 23 2 Gas Permeation Parameters and Other Physicochemical Properties of a Polymer of Intrinsic Microporosity (PIM-1) 29 Peter M. Budd, Neil B. McKeown, Detlev Fritsch, Yuri Yampolskii and Victor Shantarovich 2.1 Introduction 29 2.2 The PIM concept 30 2.3 Gas Adsorption 31 2.4 Gas Permeation 33 2.5 Inverse Gas Chromatography 35 2.6 Positron Annihilation Lifetime Spectroscopy 39 2.7 Conclusions 40 Acknowledgements 40 References 40 vi Contents 3 Addition-type Polynorbornene with Si(CH3)3 Side Groups: Detailed Study of Gas Permeation, Free Volume and Thermodynamic Properties 43 Yuri Yampolskii, Ludmila Starannikova, Nikolai Belov, Maria Gringolts, Eugene Finkelshtein and Victor Shantarovich 3.1 Introduction 43 3.2 Experimental 45 3.3 Results and Discussion 45 3.3.1 Physical Properties 45 3.3.2 Gas Permeability 45 3.3.3 Sorption and Diffusion 50 3.3.4 Free Volume 50 3.4 Conclusions 55 References 56 4 Amorphous Glassy Perfl uoropolymer Membranes of Hyfl on AD®: Free Volume Distribution by Photochromic Probing and Vapour Transport Properties 59 Johannes Carolus Jansen, Karel Friess, Elena Tocci, Marialuigia Macchione, Luana De Lorenzo, Matthias Heuchel, Yuri P. Yampolskii and Enrico Drioli 4.1 Introduction and Scope 59 4.1.1 Free Volume and Free Volume Probing Methods for Polymers 60 4.1.2 Details of the Photochromic Probe Method 62 4.1.3 Relevance of Free Volume for Mass Transport Properties 64 4.2 Membrane Preparation 64 4.2.1 Materials 64 4.2.2 Procedures 64 4.2.3 Membrane Properties 67 4.3 Free Volume Analysis 68 4.3.1 Photoisomerization Procedures and UV-Visible Characterization 68 4.3.2 Probes and Spectrophotometric Analysis 68 4.3.3 Free Volume Distribution 69 4.4 Molecular Dynamics Simulations 71 4.5 Transport Properties 73 4.5.1 Permeation Measurements 73 4.5.2 Data Elaboration: Determination of the Time Lag and Steady State Permeability 74 4.5.3 Vapour Permeation Measurements 76 4.6 Correlation of Transport and Free Volume 79 4.7 Conclusions 80 References 81 Contents vii 5 Modelling Gas Separation in Porous Membranes 85 Aaron W. Thornton, James M. Hill and Anita J. Hill 5.1 Introduction 85 5.2 Background 86 5.3 Surface Diffusion 88 5.4 Knudsen Diffusion 89 5.5 Membranes: Porous Structures? 90 5.6 Transition State Theory (TST) 91 5.7 Transport Models for Ordered Pore Networks 94 5.7.1 Parallel Transport Model 94 5.7.2 Resistance in Series Transport Model 95 5.8 Pore Size, Shape and Composition 95 5.9 The New Model 98 5.9.1 Enhanced Separation by Tailoring Pore Size 99 5.9.2 Determining Diffusion Regime from Experimental Flux 101 5.9.3 Predictions of Gas Separation 102 5.10 Conclusion 105 List of Symbols 106 References 107 II. Nanocomposite (Mixed Matrix) Membranes 111 6 Glassy Perfl uorolymer–Zeolite Hybrid Membranes for Gas Separations 113 Giovanni Golemme, Johannes Carolus Jansen, Daniela Muoio, Andrea Bruno, Raffaella Manes, Maria Giovanna Buonomenna, Jungkyu Choi and Michael Tsapatsis 6.1 Introduction 113 6.2 Materials and Methods 114 6.3 Results and Discussion 116 6.4 Conclusions 122 Acknowledgements 123 References 123 7 Vapor Sorption and Diffusion in Mixed Matrices Based on Tefl on® AF 2400 125 Maria Chiara Ferrari, Michele Galizia, Maria Grazia De Angelis and Giulio Cesare Sarti 7.1 Introduction 125 7.2 Theoretical Background 126 7.2.1 NELF Model 127 7.2.2 Modelling Gas Solubility Into Mixed Matrix Glassy Membranes 128 7.2.3 Modelling Gas Diffusivity and Permeability in Mixed Matrix Glassy Membranes 130 viii Contents 7.3 Experimental 132 7.3.1 Materials 132 7.3.2 Vapor Sorption 133 7.4 Results and Discussion 134 7.4.1 Vapor Sorption in Mixed Matrices Based on AF 2400 134 7.4.2 Diffusivity 137 7.4.3 Correlations for Diffusivity 138 7.4.4 Permeability and Selectivity 138 7.5 Conclusions 140 Acknowledgements 141 References 141 8 Physical and Gas Transport Properties of Hyperbranched Polyimide–Silica Hybrid Membranes 143 Tomoyuki Suzuki, Yasuharu Yamada, Jun Sakai and Kumi Itahashi 8.1 Introduction 143 8.2 Experimental 145 8.2.1 Materials 145 8.2.2 Polymerization 145 8.2.3 Membrane Formation 145 8.2.4 Measurements 146 8.3 Results and Discussion 147 8.3.1 Polymer Characterization 147 8.3.2 Gas Transport Properties of HBPI–Silica Hybrid Membranes 151 8.3.3 O2/N2 and CO2/CH4 Selectivities of HBPI–Silica Hybrid Membranes 151 8.4 Conclusions 157 References 157 9 Air Enrichment by Polymeric Magnetic Membranes 159 Zbigniew J. Grzywna, Aleksandra Rybak and Anna Strzelewicz 9.1 Introduction 159 9.2 Formulation of the Problem 160 9.2.1 One-component Permeation Process – Fick’s and Smoluchowski Equation 161 9.2.2 Diffusion Equation for Two-component Gas Mixture (Without and With a Potential Field) 164 9.3 Experimental 165 9.3.1 Membrane Preparation 165 9.3.2 Experimental Setup 166 9.3.3 Time Lag Method and D1-D8 System 167 9.3.4 Permeation Data 170 9.4 Results and Discussion 172 9.5 Conclusions 175 Contents ix Acknowledgements 178 List of Symbols 178 References 180 III.
Recommended publications
  • Membrane Seperation Processes, Supp. A
    I PROCESS ECONOMICS PROGRAM SRI INTERNATIONAL Menlo Park, California 94025 Abstract Process Economics Program Report No. 190A MEMBRANE GAS SEPARATION PROCESSES (January 1990) Advances in membrane technology in areas such as reverse osmosis and ultrafiltration have led to the development and commercial introduction of membranes for large-scale in- dustrial gas separations. This report studies four major applications--nitrogen production from air, oxygen-enriched air, hydrogen recovery from ammonia purge gas, and carbon dioxide separation from methane. Process economics for each application is presented, based on a preliminary process design. Competing separation operations are reviewed and competitive economics are evaluated for air separation by pressure swing adsorption. A technical review presents the essential criteria for designing on-site systems and membrane system attributes that affect economic competitiveness. Process design features required for the different industrial gas separations are also summarized, and the types of procedures employed to determine membrane area requirements are briefly described. a Finally, gas membrane system development activity by major world regions is presented, along with a review of the main market segments and a listing of current and potential applica- tions for gas membrane separation technology. Also, a look at the major supplier’s technology and market position is presented along with an SRI estimate of the number of currently installed units. Report No. 190A MEMBRANE GAS SEPARATION PROCESSES SUPPLEMENT A by RONALD SMITH - I I February 1990 cl a - A private report by the PROCESS ECONOMICS PROGRAM m a- Menlo Park, California 94025 a For detailed marketing data and information, the reader is referred to one of the SRI programs specializing in marketing research.
    [Show full text]
  • Gas Exchange
    Gas exchange Gas exchange occurs as a result of respiration, when carbon dioxide is excreted and oxygen taken up, and photosynthesis, when oxygen is excreted and carbon dioxide is taken up. The rate of gas exchange is affected by: • the area available for diffusion • the distance over which diffusion occurs • the concentration gradient across the gas exchange surface • the speed with which molecules diffuse through membranes. Efficient gas exchange systems must: • have a large surface area to volume ratio • be thin • have mechanisms for maintaining steep concentration gradients across themselves • be permeable to gases. Single-celled organisms are aquatic and their cell surface membrane has a sufficiently large surface area to volume ratio to act as an efficient gas exchange surface. In larger organisms, permeable, thin, flat structures have all the properties of efficient gas exchange surfaces but need water to prevent their dehydration and give them mechanical support. Since the solubility of oxygen in water is low, organisms that obtain their oxygen from water can maintain only a low metabolic rate. In small and thin organisms, the distance from gas exchange surface to the inside of the organism is short enough for diffusion of gases to be efficient. Diffusion gradients are maintained because gases are continually used up or produced. In larger organisms, simple diffusion is not an efficient way of transporting gases between cells in the body and the gas exchange surface. In many animals a blood circulatory system carries gases to and from the gas exchange surface. The gas-carrying capacity of the blood is increased by respiratory pigments, such as haemoglobin.
    [Show full text]
  • Mechanisms of Pulmonary Gas Exchange Abnormalities During Experimental Group B Streptococcal Infusion
    003 I -3998/85/1909-0922$02.00/0 PEDIATRIC RESEARCH Vol. 19, No. 9, I985 Copyright 0 1985 International Pediatric Research Foundation, Inc. Printed in (I.S. A. Mechanisms of Pulmonary Gas Exchange Abnormalities during Experimental Group B Streptococcal Infusion GREGORY K. SORENSEN, GREGORY J. REDDING, AND WILLIAM E. TRUOG ABSTRACT. Group B streptococcal sepsis in newborns obtained from GBS (5, 6). Arterial Poz fell by 9 torr in association produces pulmonary arterial hypertension and hypoxemia. with the increase in pulmonary arterial pressure (4). In contrast, The purpose of this study was to investigate the mecha- the neonatal piglet infused with GBS demonstrated both pul- nisms by which hypoxemia occurs. Ten anesthetized, ven- monary arterial hypertension and profound arterial hypoxemia tilated piglets were infused with 2 x lo9 colony forming (7). These results suggest that the neonatal pulmonary vascula- unitstkg of Group B streptococci over a 30-min period. ture may respond to bacteremia differently from that of adults. Pulmonary arterial pressure rose from 14 ? 2.8 to 38 ? The relationship between Ppa and the matching of alveolar 6.7 torr after 20 min of the bacterial infusion (p< 0.01). ventilation and pulmonary perfusion, a major determinant of During the same period, cardiac output fell from 295 to arterial oxygenation during room air breathing (8), has not been 184 ml/kg/min (p< 0.02). Arterial Po2 declined from 97 studied in newborns. The predictable rise in Ppa with an infusion 2 7 to 56 2 11 torr (p< 0.02) and mixed venous Po2 fell of group B streptococcus offers an opportunity to delineate the from 39.6 2 5 to 28 2 8 torr (p< 0.05).
    [Show full text]
  • Membrane Technologies for CO2 Separation A
    Journal of Membrane Science 359 (2010) 115–125 Contents lists available at ScienceDirect Journal of Membrane Science journal homepage: www.elsevier.com/locate/memsci Membrane technologies for CO2 separation A. Brunetti a, F. Scura a, G. Barbieri a,∗, E. Drioli a,b a National Research Council, Institute for Membrane Technology (ITM–CNR), Via Pietro BUCCI, c/o The University of Calabria, Cubo 17C, 87030 Rende CS, Italy1 b The University of Calabria, Department of Chemical Engineering and Materials, Cubo 44A, Via Pietro BUCCI, 87030 Rende CS, Italy article info abstract Article history: Today, all the existing coal-fired power plants present over the world emit about 2 billion tons of CO2 per Received 21 July 2009 year. The identification of a capture process which would fit the needs of target separation performances, Received in revised form 6 October 2009 together with a minimal energy penalty, is a key issue. Because of their fundamental engineering and Accepted 17 November 2009 economic advantages over competing separation technologies, membrane operations are, now, being Available online 26 November 2009 explored for CO2 capture from power plant emissions.The aim of this work is to provide people interested in the use of membranes in CO2 capture a general overview of the actual situation both in terms of Keywords: materials studies and global strategy to follow in the choice of the membrane gas separation with respect Membrane systems to the other separation technologies. Firstly, an overview on the polymeric membranes currently studied CO2 separation Flue gas for their use in CO2 capture and of their transport properties is proposed.
    [Show full text]
  • Air-Sea Gas Exchange
    Air-Sea Gas Exchange OCN 623 – Chemical Oceanography 17 March 2015 Readings: Libes, Chapter 6 – pp. 158 -168 Wanninkhof et al. (2009) Advances in quantifying air-sea gas exchange and environmental forcing, Annual Reviews of Marine Science © 2015 David Ho and Frank Sansone Overview • Introduction • Theory/models of gas exchange • Mechanisms/lab studies of gas exchange • Field measurements • Parameterizations Why do we care about air-water gas exchange? . Globally, to understand cycling of biogeochemically important trace gases (e.g., CO2, DMS, CH4, N2O, CH3Br) . Regionally and locally . To understand indicators of water quality (e.g., dissolved O2) . To predict evasion rates of volatile pollutants (e.g., VOCs, PAHs, PCBs) Factors Influencing Air-water Transfer of Mass, Momentum, Heat From SOLAS Science Plan and Implementation Strategy Basic flux equation Concentration gradient Flux (mol cm-3) (mol cm-2 s-1) “driving force” Gas transfer velocity (cm s-1) “resistance” k: Gas transfer velocity, piston velocity, gas exchange coefficient Cw: Concentration in water near the surface Ca: Concentration in air near the surface α: Ostwald solubility coefficient (temp-compensated Bunsen coeff) Basic conceptual model Turbulent atmosphere C Atmosphere a Laminar Stagnant Cas Boundary Layer zFilm Cws (transport by Ocean molecular diffusion) Cw Turbulent bulk liquid F = k(Cw-αCa) Air/water side resistance Magnitude of typical Ostwald solubility coefficients He ≈ 0.01 Water-side resistance O2 ≈ 0.03 CO2 ≈ 0.7 DMS ≈ 10 Air- and water-side resistance CH3Br
    [Show full text]
  • 30 Years of Membrane Technology for Gas Separation Paola Bernardo, Gabriele Clarizia*
    1999 A publication of CHEMICAL ENGINEERING TRANSACTIONS The Italian Association VOL. 32, 2013 of Chemical Engineering Online at: www.aidic.it/cet Chief Editors: Sauro Pierucci, Jiří J. Klemeš Copyright © 2013, AIDIC Servizi S.r.l., ISBN 978-88-95608-23-5; ISSN 1974-9791 30 Years of Membrane Technology for Gas Separation Paola Bernardo, Gabriele Clarizia* Istituto di Ricerca per la Tecnologia delle Membrane, ITM-CNR, Via P. Bucci, cubo 17/C, 87030 Arcavacata di Rende, CS, Italy [email protected] Membrane technology applied to the separation of gaseous mixtures competes with conventional unit operations (e.g., distillation, absorption, adsorption) on the basis of overall economics, safety, environmental and technical aspects. Since the first industrial installations for hydrogen separation in the early eighties, significant improvements in membrane quality have been achieved in air separation as well as in CO2 separation. However, beside the improvement in the materials as well as in membrane module design, an important point is represented by a correct engineering of these separation processes. The recovery of high value co-products from different industrial streams (e.g. organic vapours from off-gas streams, helium from natural gas) is an interesting application, which created a new market for gas separation membranes, coupling environmental and economic benefits. The opportunity to integrate membrane operations in ongoing production cycles for taking advantage from their peculiar characteristics has been proved as a viable approach. In this ambit, membrane systems in appropriate ranges of operating conditions meet the main requirements such as purity, productivity, energy demand of specific industrial processes.
    [Show full text]
  • Engineered Transport in Microporous Materials and Membranes for Clean Energy Technologies
    Lawrence Berkeley National Laboratory Recent Work Title Engineered Transport in Microporous Materials and Membranes for Clean Energy Technologies. Permalink https://escholarship.org/uc/item/1nb0c4hb Journal Advanced materials (Deerfield Beach, Fla.), 30(8) ISSN 0935-9648 Authors Li, Changyi Meckler, Stephen M Smith, Zachary P et al. Publication Date 2018-02-01 DOI 10.1002/adma.201704953 License https://creativecommons.org/licenses/by-nc-nd/4.0/ 4.0 Peer reviewed eScholarship.org Powered by the California Digital Library University of California REVIEW Microporous Materials www.advmat.de Engineered Transport in Microporous Materials and Membranes for Clean Energy Technologies Changyi Li, Stephen M. Meckler, Zachary P. Smith, Jonathan E. Bachman, Lorenzo Maserati, Jeffrey R. Long, and Brett A. Helms* 1. Introduction Many forward-looking clean-energy technologies hinge on the development of scalable and efficient membrane-based separations. Ongoing investment Improving the efficiency of membrane- in the basic research of microporous materials is beginning to pay dividends based separations is critical to the advance- in membrane technology maturation. Specifically, improvements in mem- ment of many clean-energy technologies, including gas and chemical separations, brane selectivity, permeability, and durability are being leveraged for more carbon capture and sequestration (CCS), efficient carbon capture, desalination, and energy storage, and the market water desalination, dehumidification, adoption of membranes in those areas appears to be on the horizon. Herein, fuel-cell technology, and electrochemical an overview of the microporous materials chemistry driving advanced energy storage (EES). Schemes to engineer membrane development, the clean-energy separations employing them, and highly selective species transport across microporous membranes have progressed the theoretical underpinnings tying membrane performance to membrane considerably in the past decade due to the structure across multiple length scales is provided.
    [Show full text]
  • Simulation of Dynamic Pressure- Swing Gas Sorption in Polymers
    ABSTRACT Title: SIMULATION OF DYNAMIC PRESSURE- SWING GAS SORPTION IN POLYMERS Heather Jane St. Pierre, Master of Science, 2005 Directed By: Professor Timothy A. Barbari Department of Chemical Engineering A transport model was developed to simulate a dynamic pressure-swing sorption process that separates binary gas mixtures using a packed bed of non-porous spherical polymer particles. The model was solved numerically using eigenfunction expansion, and its accuracy verified by the analytical solution for mass uptake from a finite volume. Results show the process has a strong dependence on gas solubility. The magnitudes and differences in gas diffusivities have the greatest effect on determining an optimal particle radius, time to attain steady-state operation, and overall cycle time. Sorption and transport parameters for three different polyimides and one copolyimide were used to determine the degree of separation for CO2/CH4 and O2/N2 binary gas mixtures. The separation results for this process compare favorably to those for membrane separation using the same polymer, and significantly improved performance when a second stage is added to the pressure-swing process. SIMULATION OF DYNAMIC PRESSURE-SWING GAS SORPTION IN POLYMERS by Heather Jane St. Pierre Thesis submitted to the Faculty of the Graduate School of the University of Maryland, College Park, in partial fulfillment of the requirements for the degree of Master of Science 2005 Advisory Committee: Professor Timothy A. Barbari, Chair Associate Professor Raymond A. Adomaitis Associate Professor Peter Kofinas © Copyright by Heather Jane St. Pierre 2005 Acknowledgements I would like to thank my advisor, Professor Barbari, for all of his help and guidance during the course of this research.
    [Show full text]
  • Modes of Mass Transfer Chapter Objectives
    MODES OF MASS TRANSFER CHAPTER OBJECTIVES - After you have studied this chapter, you should be able to: 1. Explain the process of molecular diffusion and its dependence on molecular mobility. 2. Explain the process of capillary diffusion 3. Explain the process of dispersion in a fluid or in a porous solid. 4. Understand the process of convective mass transfer as due to bulk flow added to diffusion or dispersion. 5. Explain saturated flow and unsaturated capillary flow in a porous solid 6. Have an idea of the relative rates of the different modes of mass transfer. 7. Explain osmotic flow. KEY TERMS diffusion, diffusivity, and. diffusion coefficient dispersion and dispersion coefficient hydraulic conductivity capillarity osmotic flow mass and molar flux Fick's law Darcy's law 1. A Primer on Porous Media Flow Physical Interpretation of Hydraulic Conductivity K and Permeability k Figure 1. Idealization of a porous media as bundle of tubes of varying diameter and tortuosity. Capillarity and Unsaturated Flow in a Porous Media Figure 2.Capillary attraction between the tube walls and the fluid causes the fluid to rise. Osmotic Flow in a Porous Media Figure 3.Osmotic flow from a dilute to a concentrated solution through a semi-permeable membrane. 2. Molecular Diffusion • In a material with two or more mass species whose concentrations vary within the material, there is tendency for mass to move. Diffusive mass transfer is the transport of one mass component from a region of higher concentration to a region of lower concentration. Physical interpretation of diffusivity Figure 4. Concentration profiles at different times from an instantaneous source placed at zero distance.
    [Show full text]
  • Gas-Liquid Hollow Fiber Membrane Contactors for Different Applications
    Review Gas-Liquid Hollow Fiber Membrane Contactors for Different Applications Stepan D. Bazhenov 1,*, Alexandr V. Bildyukevich 2 and Alexey V. Volkov 1 1 A.V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Moscow 119991, Russia; [email protected] 2 Institute of Physical Organic Chemistry, National Academy of Sciences of Belarus, Minsk 220072, Belarus; [email protected] * Correspondence: [email protected]; Tel.: +7-495-647-5927 (ext. 202) Received: 14 September 2018; Accepted: 2 October 2018; Published: 10 October 2018 Abstract: Gas-liquid membrane contactors that were based on hollow fiber membranes are the example of highly effective hybrid separation processes in the field of membrane technology. Membranes provide a fixed and well-determined interface for gas/liquid mass transfer without dispensing one phase into another while their structure (hollow fiber) offers very large surface area per apparatus volume resulted in the compactness and modularity of separation equipment. In many cases, stated benefits are complemented with high separation selectivity typical for absorption technology. Since hollow fiber membrane contactors are agreed to be one of the most perspective methods for CO2 capture technologies, the major reviews are devoted to research activities within this field. This review is focused on the research works carried out so far on the applications of membrane contactors for other gas-liquid separation tasks, such as water deoxygenation/ozonation, air humidity control, ethylene/ethane separation, etc. A wide range of materials, membranes, and liquid solvents for membrane contactor processes are considered. Special attention is given to current studies on the capture of acid gases (H2S, SO2) from different mixtures.
    [Show full text]
  • Visualizing Molecular Diffusion Through Passive Permeability
    COCHBI-1072; NO. OF PAGES 9 Available online at www.sciencedirect.com Visualizing molecular diffusion through passive permeability barriers in cells: conventional and novel approaches 1 1 1,2 1,3 Yu-Chun Lin , Siew Cheng Phua , Benjamin Lin and Takanari Inoue Diffusion barriers are universal solutions for cells to achieve exist at a variety of cellular structures, including the distinct organizations, compositions, and activities within a nuclear envelope, the annulus of spermatozoa, the lead- limited space. The influence of diffusion barriers on the ing edge of migrating cells, the cleavage furrow of divid- spatiotemporal dynamics of signaling molecules often ing cells, and the budding neck of yeast, as well as in determines cellular physiology and functions. Over the years, cellular extensions such as primary cilia, dendritic spines, the passive permeability barriers in various subcellular locales and the initial segment of the neuronal axon [1 ,6 ,7]. have been characterized using elaborate analytical techniques. While some diffusion barriers exist constitutively in cells, In this review, we will summarize the current state of knowledge others are highly dynamic. The importance of diffusion on the various passive permeability barriers present in barriers is further underscored by the various human mammalian cells. We will conclude with a description of several diseases which result from their dysfunction [3,6 ,8,9]. conventional techniques and one new approach based on chemically inducible diffusion trap (CIDT) for probing Diffusion barriers can be categorized into two major permeable barriers. classes based on the substrates they affect: lateral diffu- Addresses sion barriers and permeability barriers. Lateral diffusion 1 Department of Cell Biology, Center for Cell Dynamics, School of barriers localize in membranes and restrict the movement Medicine, Johns Hopkins University, United States 2 of molecules within the membrane plane such as trans- Department of Biomedical Engineering, Johns Hopkins University, membrane proteins and membrane lipids [1 ].
    [Show full text]
  • Gas Exchange in the Prone Posture
    RESPIRATORY CARE Paper in Press. Published on May 30, 2017 as DOI: 10.4187/respcare.05512 Gas Exchange in the Prone Posture Nicholas J Johnson MD, Andrew M Luks MD, and Robb W Glenny MD Introduction Overview of Gas Exchange Lung Structure Normal Exchange of Oxygen and Carbon Dioxide Abnormal Exchange of Oxygen and Carbon Dioxide Gas Exchange in the Prone Posture Under Normal Conditions Spatial Distribution of Ventilation Spatial Distribution of Perfusion Ventilation and Perfusion Matching Mechanisms by Which the Prone Posture Improves Gas Exchange in Animal Models of ARDS Additional Physiologic Effects of the Prone Posture Clinical Trials Summary The prone posture is known to have numerous effects on gas exchange, both under normal condi- tions and in patients with ARDS. Clinical studies have consistently demonstrated improvements in oxygenation, and a multi-center randomized trial found that, when implemented within 48 h of moderate-to-severe ARDS, placing subjects in the prone posture decreased mortality. Improve- ments in gas exchange occur via several mechanisms: alterations in the distribution of alveolar ventilation, redistribution of blood flow, improved matching of local ventilation and perfusion, and reduction in regions of low ventilation/perfusion ratios. Ventilation heterogeneity is reduced in the prone posture due to more uniform alveolar size secondary to a more uniform vertical pleural pressure gradient. The prone posture results in more uniform pulmonary blood flow when com- pared with the supine posture, due to an anatomical bias for greater blood flow to dorsal lung regions. Because both ventilation and perfusion heterogeneity decrease in the prone posture, gas exchange improves.
    [Show full text]