The management of hypersaline brines is a topic of growing environmental concern. While desalination is an increasingly attractive treatment option, conventional desalination technologies face technical limitations in high-salinity environments. This dissertation guides scientific development in the field of hypersaline desalination and advances our fundamental understanding of the novel technology Temperature Swing Solvent Extraction (TSSE).
Chapter 1 motivates the environmental, regulatory, economic, and water scarcity drivers for hypersaline desalination and briefly outlines the objectives and contributions of the thesis.
In Chapter 2, the sources and characteristics of hypersaline streams are introduced, and a primer on the energy requirements of high-salinity desalination is presented. The prospects and challenges of emerging technologies for hypersaline desalination are critically reviewed along the dimensions of energy consumption, fit- for-purpose compatibility, and ability to precipitate salts in the bulk solution. TSSE, which utilizes a switchable solvent with thermally responsive polarity to extract and subsequently release water from hypersaline feeds, shows particular promise in this field.
Chapter 3 of this dissertation investigates the influence of temperature on the equilibrium partitioning of water, salt, and solvent in biphasic TSSE mixtures. Analysis reveals that TSSE hypersaline desalination performance is inherently constrained by a productivity-selectivity tradeoff: as the operating temperature is tuned to improve water extraction, salt rejection worsens.
In Chapter 4, a novel configuration of TSSE with intermediate-step release (TSSE-IR) is introduced, and its desalination performance is assessed. The intermediate temperature step is demonstrated to dramatically improve salt rejection compared to the conventional single-step operation while minimizing sacrifices in water recovery yields.
Chapter 5 of the dissertation advances a physical chemistry framework for the a priori prediction of activity coefficients in TSSE biphasic systems. Water partitioning behavior is shown to be enthalpically driven, and salt partitioning behavior is determined to be primarily influenced by the anion.
In Chapter 6, the distribution behaviors of organic contaminants, which are present in real hypersaline brines, are measured in TSSE biphasic mixtures. The fate of these compounds can be reliably predicted from the physicochemical properties of octanol-water partition coefficients and acid-base dissociation constants.
Finally, Chapter 7 details the contributions and implications of the dissertation, offering suggestions for targeted areas of future research. Overall, this work helps to advance the development of cost-effective and energy-efficient desalination of high-salinity streams to enable a circular water economy.
| Identifer | oai:union.ndltd.org:columbia.edu/oai:academiccommons.columbia.edu:10.7916/9mgt-wz65 |
| Date | January 2024 |
| Creators | Shah, Kinnari Malav |
| Source Sets | Columbia University |
| Language | English |
| Detected Language | English |
| Type | Theses |
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