Award Date

May 2023

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical Engineering

First Committee Member

Jeremy Cho

Second Committee Member

Kwang Kim

Third Committee Member

Jaeyun Moon

Fourth Committee Member

Hui Zhao

Fifth Committee Member

Yingtao Jiang

Number of Pages

126

Abstract

Water scarcity is a global issue affecting billions of people, and atmospheric water harvesting (AWH) technology has been identified as a potential solution. However, existing single-material AWH approaches have limited water harvesting yields due to alternated water capture, storage, and release stages, and only function within a high relative humidity range. In my doctoral research project, we developed a bio-inspired, hydrogel-based multi-layer AWH approach that allows for segregated capture, storage, and release stages, and is envisioned to have higher daily water harvesting efficiency even in low-humidity areas. My research began with understanding the relations between hydrogel mechanical stiffness, hydraulic permeability, and swelling behavior, confirming the feasibility of hydrogel polymers for our AWH approach, and concluded with building and experimentally testing our multi-layer AWH design.This thesis reports on my doctoral research, including the following: 1. Development of a simple power-law relationship between hydrogel elastic modulus and swelling, using de Gennes’ semi-dilute polymer theory. The ratio of moduli at arbitrary and wet swelling states is equal to the swelling ratio with a power of −9/4, and this relationship can be used to predict hydrogel stiffness or swelling at varied relative humidities. 2. The combination of de Gennes’ theory and the Kozeny-Carman equation led to a scaling law describing the highly corresponding relationship between hydraulic permeability and stiffness of hydrogels, which has a power of −8/9. 3. Introduction of a bio-inspired, hydrogel-based multi-layer AWH approach induced by saturated salt solution. Experimental test results confirm that our AWH design produces higher water capture yields than any existing approach, even at much lower relative humidities. Our design is potentially able to provide enough daily drinking water for 2-4 adults in the driest city of the United States, Las Vegas, or provide enough safely managed drinking water for billions of people through the world.

Keywords

Capture; Hydrogel; Membrane; Poroelastic; Segregation; Water

Disciplines

Engineering Science and Materials | Materials Science and Engineering | Mechanical Engineering

File Format

pdf

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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