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Design, Synthesis, and Fabrication of Membranes and Modules for Water Desalination: Porous Materials with Special Wettability for Membrane Distillation
Water scarcity induced by population growth and climate change has increased the demand for alternative methods to provide additional potable water for the world. Currently, the primary approach to improve water supply beyond the hydrological cycle is water desalination. Among all the techniques, membrane-based technologies have been the most promising candidates. One of these candidates is membrane distillation (MD). Although MD has several advantages over other technologies, it has not been fully developed for water desalination. The less-than-mature state of the technology is attributed to its lower permeate flux and energy efficiency compared to those of fully commercialized desalination processes such as reverse osmosis (RO). In this work, by targeting the limitations of the MD process, we designed membrane modules with enhanced energy efficiency and water production through a model-guided approach. Subsequently, following our optimal modeling results, membrane modules were fabricated using additive manufacturing. We found that, compared to the randomly packed modules, hollow fiber membrane modules with organized packing provide higher energy efficiency and water production. Besides, we developed scalable methods for the fabrication of porous membranes and interfaces for the desalination of oil-contaminated water resources. We realized that by tailoring the surface chemistry of hydrophobic membranes using strong alkaline solutions, we can create interfaces that show stable underwater oleophobicity. We also targeted the desalination of low-surface-tension water resources (e.g., solutions containing surfactants). Accordingly, by adjusting the process and reaction parameters in a liquid-free process, initiated chemical vapor deposition (iCVD), we devised a bottom-up technique for assembling polymeric reentrant structures on porous substrates. The method was successfully applied to both flat sheet and hollow fiber membranes. The produced membranes showed exceptional performance in the desalination of low-surface-tension water solutions. Finally, we targeted the low energy efficiency of the MD process. For this reason, we designed and fabricated composite porous domains with high solar absorption. Subsequently, we built thermal desalination devices with the capability of harvesting solar energy.
Mohammadi Ghaleni, Mahdi, "Design, Synthesis, and Fabrication of Membranes and Modules for Water Desalination: Porous Materials with Special Wettability for Membrane Distillation" (2020). ETD collection for University of Nebraska - Lincoln. AAI27955703.