Advanced characterization of transport and microstructural properties in membrane materials

Membranes are employed in a variety of sustainable water treatment and energy conversion technologies. Advancing membrane materials for new separations includes unraveling the complex structure-property relationships that govern water and salt transport in conjunction with scaling processing methods. Material properties can be tuned by increasing salinity, adjusting humidity, or introducing filler particles to achieve desired transport metrics. These modifications impact water and salt diffusion as well as microstructural characteristics in the membrane materials, yet the detailed relationships between membrane performance, processing conditions, and transport properties remain to be fully characterized. Although extensive membrane research has been conducted, a need exists to better understand how compositional changes impact transport in membrane materials as well as resulting membrane properties. Understanding the structure- property-processing relationships of membrane materials is crucial for optimizing performance in practical applications. Here, I examine three classes of membrane materials used in water treatment and energy conversion applications: polyamide reverse osmosis membranes, Nafion cation (proton) exchange ionomers, and graphene oxide-based nanofiltration membranes. Advanced characterization techniques quantify water diffusion coefficients and relaxation times in polymer membranes under varying environmental conditions. Additionally, aggregation behaviors and interlayer binding interactions between graphene oxide sheets and intercalant molecules are examined. Diffusion measurements reveal distinct transport mechanisms of water and salt in charged and uncharged polymer membrane materials. Aggregation behavior observed in graphene oxide (GO) dispersions and salt rejection measurements with GO membranes bridges the gap between fundamental material properties and the membrane performance.

Level thesis:degree_level

Doctoral

Department dc:contributor.department

Mechanical Engineering

Grantor dc:publisher

Georgia Institute of Technology

Year dc:date.issued

2025

Author dc:creator

• Garell, Madeline

Advisor dc:contributor.advisor

• Hatzell, Marta C.

Committee members dc:contributor.committeemember

• Menon, Akanksha
• Lee, Seung Woo
• Hesketh, Peter
• Nair, Sankar

• Membranes
• nuclear magnetic resonance
• polyamide
• Nafion
• graphene oxide

Language dc:language.iso

en_US

Handle dc:identifier.uri

https://hdl.handle.net/1853/78648

OAI identifier oai:identifier

oai:repository.gatech.edu:1853/78648