Ion Transport & Electrokinetics in Colloidal Particle Networks

Currently around 10 percent of the people in the world are living under conditions of extreme water scarcity and it is expected that this will only become worse in the near future for various reasons such as climate change. For this reason, it is important that we find alternative water resources to reduce the current and future water scarcity. One option to reduce this problem is to remove the salt of brackish (slightly saline) waters. This could be done with a technique called electrodialysis, which removes salt from water with electricity and cat- and anion selective membrane pairs. However, to implement this technique it is important to optimize the ion transport to make this technique more attractive for industrial applications. In this thesis the ion-transport a fundamental study is conducted for electrodialysis applications using a model system composed of colloidal particle networks. Colloidal particle networks are porous materials composed of close-packed nano- or microparticles and could be useful to study a wide variety of different electro-driven processes
In Chapter 1, some background information on various types of electrodialysis processes and their ion transport limitations is provided as well as for instance the difference between ion-exchange membranes and colloidal networks. Next to this the origin of several relevant electrokinetic phenomena are discussed. In Chapter 2, the use of alternating conductive and non-conductive patched model membranes is explored to optimize the transport of ions for electrodialysis. In Chapter 3 the influence of charge regulation on the performance of shock electrodialysis was numerically studied. Chapter 4 discusses the water splitting, water transport and temperature development characteristics for a thick model bipolar membrane that is composed of anion and cation ion exchange resin particles. In Chapter 5 a commercial anion exchange membrane is coated with MOF film via a novel synthesis method. In Chapter 6 a particle focusing technique based on AC-EOF and the induced dipole force is explored both by an experimental and numerical study. In Chapter 7 the main conclusions of the thesis are presented and further ideas for follow-up studies are provided