MURDOCH UNIVERSITY The Electrodialysis of Lithium Sulphate to Lithium Hydroxide ENG470 – Engineering Honours Thesis Thesis submitted to the School of Engineering and Information Technology, Murdoch University, to fulfil the requirements for the degree of Chemical and Metallurgical Engineering Honours. Written by: Hollie Harrison Unit Coordinator: Professor Parisa Arabzadeh Bahri & Dr. Gareth Lee Thesis Supervisors: Dr Aleks Nikoloski This page was intentionally left blank Author’s Declaration I declare that this thesis is my own account of my research and contains as its main content work which has not previously been submitted for a degree at any tertiary education institution. Hollie Harrison I Acknowledgements Firstly, I would like to sincerely thank my supervisor, Dr. Aleks Nikoloski for his unwavering support and encouragement throughout this project. I would also like to acknowledge and wholeheartedly thank Kwang-loon Ang (Allan) for his hours of work in helping me to complete this research, without whom I would not have been able to complete this thesis. I would also like to thank Jacqueline Briggs for all of her vital assistance and patience with the ion-chromatography machine. To my friends within the university, I would like to thank you for your help, support and advice, without which this project and university life would have been the most stressful experience of my life. Each one of you has helped me to the best of your ability, and I am so very grateful for that. To my family for their complete and unconditional love, support and encouragement throughout my entire student career. I would not have had the ability to complete this degree without you, and for that I cannot thank you guys enough. Lastly to my amazing partner, Bevan Green, thank you for all of the lunches you brought me when I had no time to get food. Thank you for your unconditional support and all of the encouragement you’ve given me over the past year. II Abstract There is currently an increasing demand for lithium-ion batteries, and therefore a push within the industry to produce lithium hydroxide. Electrodialysis has been shown to be a promising new technology for producing lithium hydroxide. A three-compartment batch electrodialysis cell was constructed, utilising an anionic exchange membrane and a cationic exchange membrane. This cell was constructed in order to produce lithium hydroxide from lithium sulphate salt. The cell was run under multiple different conditions to observe the effect that they would have on the recovery of lithium within the lithium hydroxide of the catholyte compartment within the cell. The initial pH of the solution, the temperature of the system, the initial concentration of lithium sulphate and the residence time within the cell were all tested in separate experiments in order to observe how they would influence the system and the production of lithium hydroxide. The results of this study indicated that by decreasing the initial concentration of the lithium sulphate within the cell, the lithium recovery is dramatically increased, at 30 wt.% lithium sulphate, 18.3% of the lithium is recovered within 4 hours into the catholyte solution as lithium hydroxide. At 5 wt.% lithium sulphate, 81.2% of the lithium is recovered within 4 hours into the catholyte as lithium hydroxide. The results also suggest, the rate of production of lithium hydroxide is fastest when the residence time within the cell is reduced, however, a longer residence time within the cell will increase the lithium recovery. A 4-hour test at 30 wt.% of lithium sulphate yielded a 23.1% lithium recovery within the catholyte solution. When this residence time was doubled, the recovery was increased to 37% lithium within the catholyte as lithium hydroxide. III This page was intentionally left blank IV Table of Contents Author’s Declaration ...................................................................................................... I Acknowledgements ....................................................................................................... II Abstract ........................................................................................................................ III Table of Tables ........................................................................................................... VI Table of Figures ......................................................................................................... VII 1. Chapter 1- Introduction .......................................................................................... 1 2. Chapter 2- Literature Review ................................................................................. 3 2.1. Introduction to Lithium .................................................................................. 3 2.1.1. Uses for Lithium ........................................................................................ 3 2.1.2. History of Lithium ..................................................................................... 5 2.1.3. Lithium Hydroxide (LiOH) ....................................................................... 6 2.2. Electrodialysis ................................................................................................ 7 2.3. Membranes ................................................................................................... 11 2.3.1. Types of membranes explored ................................................................. 11 2.4. Electrolytic Solutions ................................................................................... 20 2.4.1. Catholyte .................................................................................................. 21 2.4.2. Anolyte .................................................................................................... 22 2.5. Factors That Can Affect Efficiency ............................................................. 22 2.6. Conclusions and Recommendations ............................................................ 25 3. Chapter 3- Materials and Methods ....................................................................... 28 3.1. Solution Preparation..................................................................................... 28 3.2. Analytical Methods ...................................................................................... 29 3.3. Experimental Materials and Set-up ......................................................... 30 3.4. Experimental Method................................................................................... 35 3.4.1. Preliminary Experiment ........................................................................... 35 3.4.2. pH Alteration ........................................................................................... 37 3.4.3. Temperature ............................................................................................. 37 3.4.4. Initial Concentration of Li2SO4 ............................................................... 37 3.4.5. Residence Time ....................................................................................... 38 4. Chapter 4- Results and Discussion ...................................................................... 39 4.1. Preliminary Experiment ............................................................................... 39 4.2. Effect of pH.................................................................................................. 43 4.3. Effect of Temperature .................................................................................. 48 4.4. Effect of Starting Concentration .................................................................. 54 4.5. Effect of Residence Time ............................................................................. 62 4.6. General Discussion ...................................................................................... 70 5. Chapter 5- Conclusion and Recommendations .................................................... 73 5.1. Future Work ................................................................................................. 74 6. References ............................................................................................................ 75 7. Appendix .............................................................................................................. 80 V Table of Tables Table 1: Calculated lithium demand (Basic Scenario) forecast and share in 2020 for different applications Modified from (Martin et al., 2017). .................................. 4 Table 2: Operating conditions for each experiment ..................................................... 35 Table 3: Mass transfer and recovery, experiment 1: preliminary ................................ 43 Table 4: Mass transfer and recovery, experiment 2: pH 11 ......................................... 47 Table 5: Mass transfer and recovery, experiment 3: pH 7 ........................................... 48 Table 6: Mass transfer and recovery, experiment 4: 40°C,.......................................... 54 Table 7: Mass transfer and recovery, experiment 5: 60°C,.......................................... 54 Table 8: Mass transfer and recovery, experiment 6: 15 wt.% ..................................... 61 Table 9: Mass transfer and recovery, experiment 7: 10 wt.% ..................................... 61 Table 10: Mass transfer and recovery, experiment 8: 5 wt.% ..................................... 62 Table 11: Mass transfer and recovery, experiment