Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Kundu, Santanu

Committee Member

Rai, Neeraj

Committee Member

Scherrer, Susan

Committee Member

Toghiani, Hossein

Date of Degree

12-8-2023

Original embargo terms

Embargo 2 Years

Document Type

Dissertation - Open Access

Major

Chemical Engineering

Degree Name

Doctor of Philosophy (Ph.D)

College

James Worth Bagley College of Engineering

Department

Dave C. Swalm School of Chemical Engineering

Abstract

Electrodialysis is a membrane separation process that uses an electrical potential to drive the separation. The performance of these systems is largely based on the performance of their ion exchange membranes (IEMs). This research focused on enhancing the performance of IEMs for electrodialysis through surface modification techniques involving chitosan bonded to the surface of commercially available cation exchange membranes (CEMs). The surface functionalization techniques resulted in membranes with improved electrodialysis performance. This research also explored the processing framework to produce functionalized sulfonated PEEK (sPEEK) nanofibers for future consideration as cation exchange membranes.

Chitin was deacetylated to form the functionalized biopolymer chitosan, then applied to the surface of CEMs, rendering them more hydrophilic. These membranes were evaluated across several electrodialysis performance metrics. Results demonstrate that adjusting the degree of deacetylation of chitosan to enhance membrane hydrophilicity positively impacted electrodialysis performance. Furthermore, this research evaluated the effectiveness of similarly functionalized membranes to extract Lithium from brine solutions. The chitosan-coated membranes showed improved electrodialysis performance, including enhanced flux, limiting current density, system resistance, selectivity, and fouling resistance.

Lastly, the sPEEK nanofibers were produced for the fabrication of ion exchange membranes by manipulating operational parameters to assess their impact. This research presents the successful functionalization of PEEK via sulfonation and electrospinning of the resulting sPEEK. These nanofibers were then pressed to form a solid sPEEK membrane. It was observed that changes in electrical potential and rotational speed influenced fiber diameter and spinnability.

A correlation was established between membrane surface hydrophilicity and electrodialysis performance metrics in desalination and lithium extraction applications. This research advanced the understanding of structure-property relationships for CEMs. The research herein proposes techniques for industries such as desalination and lithium extraction that can meet growing demands for clean water and sustainable methods for producing high-value raw material streams.

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Available for download on Monday, December 15, 2025

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