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New Mexico State University (2021)

Development of Porous Hydrogels by Templating Approaches as a Solution to Water Scarcity

Zowada, Ryan

Titre : Development of Porous Hydrogels by Templating Approaches as a Solution to Water Scarcity

Auteur : Zowada, Ryan

Université de soutenance : New Mexico State University

Grade : Doctor of Philosophy (PhD) in Engineering 2021

Résumé
Technologies to reduce water scarcity continue to be an extensively researched topic due to the impacts of climate change and increase in population. The majority of consumptive water use is appropriated to irrigation for agriculture. While better irrigation practices could be implemented, further technologies are advanced to improve water use efficiency. The focus of this work is on applications of templated porous hydrogels as a potential mean for reduction in water scarcity. Porous hydrogels are an attractive solution to water scarcity issues due to their passive mechanism of absorbing water and reduced material cost from their porosity. For this work, the methods used for fabricating porous hydrogels were foam-templating and high internal phase emulsion (HIPE) templating. Foam and HIPE-templating were compared in this work due to their respective benefits. The HIPE-templating has structure tunability, lower void sizes, and higher interconnectivity of the resulting foam. The developed foam-templating method shows a lower material cost and lower mixing-energy requirements, as well as a highly interconnected foam. The water uptake capabilities and mechanical strength of the hydrogels are not sacrificed by this method while providing an average void diameter of <100 μm. Applications to reduce water scarcity for the templated foams were also explored in this work. Water scarcity due to arsenic contamination typically affects rural areas that need water remediation. HIPE-templated hydrogels were shown to have high water uptake capabilities (up to 4000 wt.% increase) as well as the arsenic removal capabilities. HIPE-templated hydrogels impregnated with hydrated ferric oxide nanoparticles and found they could remove up to 50% of arsenic in highly concentrated arsenic solutions (4.5 ppm). Water use efficiency for agriculture was also explored as an application. HIPE-templated hydrogels were used to improve water retention in sandy soil by preventing drainage loss and improve plant available water. The polyHIPE shows rapid water uptake due to capillary action and showed an increase in saturated water content up to 4% when implemented in sandy soil. Foam-templated bio-based polymers for reduction in water scarcity were also studied as a biodegradable soil amendment. Chitosan foams were successfully fabricated using the developed foam-templated method where void sizes range 50–200 μm. These foams also show high water uptake of up to 1000 wt.% increase due to their high porosity (> 90%). The overall research in this project shows the wide range of applicability that templated foam hydrogels have for water scarcity issues as well as extended applications for agricultural, environmental, and biomedical fields.

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Page publiée le 7 décembre 2021