Date of Award

3-3-2021

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Applied Science

First Advisor

Tansel Karabacak

Abstract

Atmospheric water generation, which involves condensing water vapor in humid ambient air on a solid surface, offers an attractive solution to water-deficiency problems such as the need for drinking water in developing countries, deserts, remote areas like mountain tops, or for producing agricultural water under drought conditions. Selection of materials for the condensation surface faces two opposing challenges. Specifically, when a film-like condensation forms on a hydrophilic surface, it covers the solid surface and hinders further condensation. On the other hand, the use of a hydrophobic surface reduces the nucleation rate of condensation and therefore reduces the water collection efficiency. An ingenious solution comes from nature. An insect named the Namib Desert beetle, which lives in one of the most parched zones in South Africa, generates its own drinking water using a unique design on its wings. This clever design has been mimicked in a few recent studies to develop bioinspired atmospheric water generators. Hot water treatment HWT and sandblasting can produce hierarchically rough superhydrophobic SHP surfaces with superior water departure that can significantly enhance the water generation efficiency. The metallic response to HWT process were screened including most elemental metals from the periodic table of elements as well as some widely used alloys and compounds. Later in this work, the optimized HWT parameters such as treatment time and temperature were considered in the fabrication of nano-roughness features on the samples. Also, the effect of the abrasive particle size (mesh number) for the sandblasting process on the surface wettability was evaluated and the optimum mesh number considered in the fabrication of the micro-structure on the metallic surface for hierarchical surfaces. Thus, surfaces of homogenous and heterogeneous wettability were fabricated, and their atmospheric water generation efficiency were measured on the Al alloy, Cu, and Zn surfaces. Furthermore, groovy textured surfaces that mimic bioinspired atmospheric water generation of superhydrophobic wettability were tested and their ability to generate water was measured. Finally, the optimized sample tilting angle and the amount of water generation were evaluated and reported.

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