Graduate Studies

 

First Advisor

Mona Bavarian

Degree Name

Doctor of Philosophy (Ph.D.)

Committee Members

Nirupam Aich, Siamak Nejati, William H. Velander, Yasar Demirel

Department

Chemical and Biomolecular Engineering

Date of this Version

8-2025

Document Type

Dissertation

Citation

A dissertation presented to the Graduate College of the University of Nebraska in partial fulfillment of requirements for the degree of Doctor of Philosophy

Major: Chemical and Biomolecular Engineering

Under the supervision of Professor Mona Bavarian

Lincoln, Nebraska, August 2025

Comments

Copyright 2025, Sarang Ismail. Used by permission

Abstract

The global urgency to mitigate anthropogenic CO₂ emissions has intensified the pursuit of energy-efficient separation technologies. Supported Ionic Liquid Membranes (SILMs) have emerged as promising candidates for CO₂ capture due to their tunable solubility-selectivity and low energy requirements. However, challenges such as mechanical instability, limited scalability, and trade-offs in transport performance have impeded their widespread adoption.

This thesis explores a systematic approach to designing and optimizing SILMs for enhanced CO₂ separation by tailoring polymer–ionic liquid interactions, processing conditions, and material architectures. A comprehensive set of studies were conducted using poly(vinylidene fluoride) (PVDF) with varying molecular weights, different grades of PEBAX®, and green solvents like Rhodiasolv® PolarClean. Ionic liquids such as [EMIM][Tf₂N] were incorporated to fabricate SILMs, and their performance was evaluated using gravimetric sorption and various material and thermal characteristics techniques.

Key findings include the identification of optimal PVDF molecular weight (180,000 g/mol) that balances crystallinity and sorption site density, and the use of PEBAX® RNEW with green solvents yielding highly CO₂-selective membranes. AI-guided latent space modeling further accelerated the prediction of high-performance SILM compositions. Additionally, porphyrin-based covalent organic frameworks (COFs) and emerging 2D materials such as MXenes were explored as novel fillers to enhance membrane performance through synergistic sorption and transport mechanisms.

This work advances the fundamental understanding of structure-property relationships in SILMs and introduces scalable, environmentally conscious fabrication strategies. The outcomes support the development of next-generation membranes for carbon capture, aligning with global decarbonization and circular economy goals.

Advisor: Mona Bavarian

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