Sharmila M. Mukhopadhyay (Advisor), Amir Farajian (Committee Member), H. Daniel Young (Committee Member), Barry Milligan (Other)
Master of Science in Materials Science and Engineering (MSMSE)
The primary purpose of this study is to investigate the role of surface nano-structuring in fluid separation. It is hypothesized that hierarchical carbon structures consisting of aligned carbon nanotube arrays strongly adhered to the surface of porous carbon solids such as fabric and foam, can be used for separation of polar and non-polar fluids by selective wettability of one fluid and rejection of another. The vertically-aligned carbon nanotube arrays, as synthesized, possess super hydrophobicity demonstrated by high water contact angle on their surfaces. On the other hand, they are incredibly oleophilic, showing a high affinity to adsorb oil. These properties make it possible for the carbon nanotube arrays to adsorb and reject certain liquids based on their polarity selectively. By investigating the wettability of these hierarchical structures with water and variety of model oils, initially in the presence of air, and later in the presence of each other, we demonstrate that selective capillary-based devices are thermodynamically possible under different conditions. We have measured the sorption capacity of the model oils in this study, and we have shown the increase in sorption capacity by the specific surface area. We have also shown that adsorption in multiple cycles does not decrease the sorption capacity for these structures, and therefore, they have the potential to be used multiple times without losing their efficiency. Finally, we investigated the selective wettability and separation phenomena of oil-water mixtures, with and without surfactants. These studies show the capabilities and practical limitations of these porous hierarchical structures in the separation of oil from water. We suggest that porosity control of the substrates and controlling the direction of the liquid flow could be an essential part of the future studies for making these structures more effective membranes.
Department or Program
Department of Mechanical and Materials Engineering
Year Degree Awarded
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