Towards a Surface Chemistry and Multiscale Texturation Toolkit for the Separation and Handling of Viscous Hydrocarbons
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The response of a liquid when placed onto a surface depends on the inherent properties of the liquid (cohesive forces within the liquid), the texturation of the surface (which can drastically increase the inherent wettability of surfaces or provide reentrant curvature), and the surface energy at the solid/liquid interface. This dissertation focuses on two main thrusts: (a) the separation of viscous oil and water emulsions using an inorganic membrane comprising ZnO nanotetrapods embedded on a stainless steel mesh to induce hierarchical texturation and exploit the surface-tension-mediated differential wettability of such fluids; and (b) the tuning of surface properties including mesoscale texturation and chemical functionalization to altogether prevent the wetting of surfaces by either oil or water by suspending liquid droplets in metastable states. The properties of the surfaces can be drastically modified by changing the surface roughness on the micrometer scale and the nanometer scale, as well as by altering the chemistry of the surfaces by functionalizing them with self-assembled monolayers (SAMs). Understanding the influence of these parameters is critical for programmably defining the behavior of liquids and their emulsions when interacting with such surfaces. The development of methods for precisely defining the wettability of surfaces by fluids exhibiting complex rheological properties has implications for the separation of heavy oil/water emulsions, the transportation and handling of oil, and the cleanup of oil spills in marine environments. This dissertation describes the synthesis of such surfaces and membranes, as well as their tunability based on altering the loading of ZnO nanotetrapods and their functionalization with amorphous SiO2 or perfluorinated phosphonic acid monolayers.
O'Loughlin, Thomas Edward (2018). Towards a Surface Chemistry and Multiscale Texturation Toolkit for the Separation and Handling of Viscous Hydrocarbons. Doctoral dissertation, Texas A&M University. Available electronically from