Development of State-Of-The-Art Interfacially Polymerized Defect-Free Thin-Film Composite Membranes for Gas- and Liquid Separations Dissertation by Zain Ali (Bajwa) In Partial Fulfillment of the Requirements For the Degree of Doctor of Philosophy King Abdullah University of Science and Technology Thuwal, Kingdom of Saudi Arabia © April, 2018 Zain Ali All Rights Reserved 2 EXAMINATION COMMITTEE PAGE The dissertation of Zain Ali is approved by the examination committee. Committee Chairperson: Prof. Ingo Pinnau Committee Members: Prof. Yu Han, Prof. Mohamed Eddaoudi, Prof. Sandra Kentish. 3 ABSTRACT Development of State-Of-The-Art Interfacially Polymerized Defect-Free Thin-Film Composite Membranes for Gas- and Liquid-Separations Zain Ali This research was undertaken to develop state-of-the-art interfacially polymerized (IP) defect-free thin-film composite (TFC) membranes and understand their structure-function- performance relationships. Recent research showed the presence of defects in interfacially polymerized commercial membranes which potentially deter performance in liquid separations and render the membranes inadequate for gas separations. Firstly, a modified method (named KRO1) was developed to fabricate interfacially polymerized defect-free TFCs using m-phenylene diamine (MPD) and trimesoyl chloride (TMC). The systematic study revealed the ability to heal defects in-situ by tweaking the reaction time along with considerably improving the membrane crosslinking by controlling the organic solution temperature. The two discoveries were combined to produce highly crosslinked, defect-free MPD-TMC polyamide membranes which showed exceptional performance for separating H2 from CO2. Permeance and pure-gas selectivity of the membrane increased with temperature. H2 permeance of 350 GPU and H2/CO2 selectivity of ~100 at 140 °C were obtained, the highest reported performance for this application using polymeric materials to date. Secondly, the membranes produced using KRO1 were tested for reverse-osmosis (RO) performance which revealed significantly improved boron rejection compared to 4 commercial membranes reaching a maximum of 99% at 15.5 bar feed pressure at pH 10. The study also unveiled direct correlations between membrane crosslinking and salt separation performance in addition to the membrane surface roughness. Thirdly, this was followed by replacing the conventional IP TMC monomer with a large, rigid and contorted tetra-acyl chloride (TripTaC) monomer to enhance the performance of IP TFCs. The fabricated TFCs showed considerable performance boosts especially for separating of small solutes from organic solvents such as methanol. A rise in H2 permeance was also observed compared to the conventional MPD-TMC TFCs while reaching a maximum H2/CO2 selectivity of 9 at 22 °C. Finally, the research was completed by showing the potential of KRO1 for fabrication of defect-free TFCs using a range of aqueous diamine monomers. KRO1 enabled defect-free gas properties for all monomers used showing exceptional performance for separating H2- CO2 and O2-N2 mixtures. It was further shown that the formulation could also improve the RO separation of interfacially polymerized polyamide TFCs beyond those shown by commercially available TFCs. 5 ACKNOWLEDGMENTS This dissertation is dedicated to my parents who have spent their lives instilling the importance of education, hard work and being a good human-being in me and my siblings. My father who has shown me the importance of responsibility and commitment and my mother who showed us the importance of love, relationships and to fight for the betterment of human beings. My amazing sisters, Zahra and Hira, and my incredible brother, Zawar, who have filled my life with love and pride. My wife, Emilie, who has been with me with the ups and downs of research life and whose contributions to this work and my life in KAUST have been immeasurable. And the newest addition to our life, little Mustafa, a reminder of what matters in life. Without your love, this would all be meaningless. My friends for many lifetimes; Humza, Tayyab, Haris, Machu, Moiz, Kamal, Asghar, Ibrahim, Fawad, Lala, Tanwiri, Imran. Those who I have gotten to meet in KAUST; Moustapha, Joel, Balawi, Luca, Pepe, Faheem, Anton, the Budget meal, the Grape Apes. All of you have helped me become a better person. Eric Litwiller, the complete engineer, who has selflessly shared all his knowledge, skills, expertise. His critical thinking and application of the scientific method will serve as the gold standard for me. My colleagues and collaborators; Federico, Giuseppe, Jintang, Ramy, Mahmood, Wojciech, Ainur, Khalid, Yasmeen, Anton, Yingge, Prof. Udo, Hakkim, Nasser, Fahd, Rakan, Saud, Aziz, Dr. Ma, Dr. Yichang Pan, whose kindness and work have made this Ph.D. bearable in the brutal world of academia. My academic supervisor, Prof. Ingo Pinnau, for his guidance and the incredible amount of knowledge and expertise he has shared with all our group and furthermore for the fantastic 6 team he assembled. And finally a big thanks to the committee members, Prof. Yu Han, Prof. Mohamed Eddaoudi and, Prof. Sandra Kentish, who I am honored to have as a part of my Ph.D. defense. Zain Ali KAUST April 15, 2019 7 TABLE OF CONTENTS EXAMINATION COMMITTEE PAGE ......................................................................2 ABSTRACT ...................................................................................................................3 ACKNOWLEDGMENTS .............................................................................................5 TABLE OF CONTENTS ..............................................................................................7 LIST OF FIGURES ..................................................................................................... 13 LIST OF TABLES ....................................................................................................... 19 Chapter 1. Membrane-based Separation: Past, Present, and Future ........................ 21 1.1. Early Development of Membrane Science ....................................................... 21 1.1.1. Conceptual Development .......................................................................... 21 1.1.2. Towards Commercialization ..................................................................... 22 1.1.3. Advantages of Membrane Technology...................................................... 27 1.2. Current State-Of-The-Art Membranes ............................................................. 30 1.2.1. Membranes for Gas Separation ................................................................. 30 1.2.2. Membranes for Liquid Separations ........................................................... 38 1.3. The Future of Membrane Science .................................................................... 43 1.3.1. Membranes for Gas Separation ................................................................. 43 1.3.2. Future Of Liquid Separations .................................................................... 47 1.3.3. Promising Materials ................................................................................. 53 1.4. Dissertation Goals ........................................................................................... 55 8 1.5. References ....................................................................................................... 58 Chapter 2. Theory and Background ........................................................................... 67 2.1. Gas Transport through Membranes .................................................................. 67 2.1.1. Pore-Size-Dependent Transport ................................................................ 69 2.1.2. The Solution-Diffusion Model .................................................................. 72 2.1.3. Characterizing Transport .......................................................................... 78 2.1.4. Permeability/Selectivity Trade-Offs.......................................................... 80 2.1.5. Process Considerations ............................................................................. 82 2.2. Liquid Transport through Membranes .............................................................. 91 2.2.1. Solution-Diffusion .................................................................................... 91 2.2.2. Characterizing Transport .......................................................................... 95 2.2.3. Permeability/Selectivity Trade-Offs.......................................................... 96 2.2.4. Process Considerations ............................................................................. 97 2.3. Interfacial Polymerization ................................................................................ 98 2.3.1. Introduction .............................................................................................. 98 2.3.2. Mechanism of Thin-Film Formation ....................................................... 104 2.3.3. Significant Fabrication Parameters ......................................................... 107 2.3.4. Interfacially polymerized TFCs for gas separations ................................ 112 2.4. References ..................................................................................................... 115 Chapter 3. Materials and Methods ........................................................................... 124 9 3.1. Materials ......................................................................................................