Date of Graduation

7-2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Chemical Engineering

Advisor/Mentor

Hestekin, Jamie

Committee Member

Hesteki, Christa

Second Committee Member

Monroe, Jacob

Third Committee Member

Wolchok, Jeffrey

Fourth Committee Member

Walters, Keisha

Keywords

cellulose membrane, dialysis application, TEMPO oxidation, Kidney diseases, membrane performance, ionic liquid, cosolvent, nanocellulose

Abstract

Chronic kidney disease affects approximately 35 million individuals in the United States, with nearly 550,000 patients dependent on dialysis for survival. Chronic kidney disease and end stage kidney disease impose substantial burdens on patients and healthcare systems, driving demand for improved dialysis membranes with enhanced flux, selectivity, and biocompatibility. The performance of dialysis membranes plays a critical role in treatment efficiency, governing solute transport, fluid removal, and overall therapeutic outcomes. In hemodialysis, membranes must achieve an optimal balance between high permeability and selective solute rejection while maintaining mechanical stability and long-term biocompatibility. Conventional dialysis membranes are commonly fabricated from polymeric materials such as cellulose acetate, polysulfone, and polyethersulfone, though challenges related to fouling and limited tunability persist. Cellulose-based materials, particularly TEMPO-oxidized nanocellulose, have emerged as promising candidates for next-generation hemodialysis membranes due to their inherent hydrophilicity, biocompatibility, and tunable surface chemistry. However, processing cellulose into functional membranes requires effective dissolution strategies, and the addition of cosolvents to ionic liquid systems represents an important lever for controlling solution properties and membrane morphology. In this study, ultrafiltration TEMPO-modified nanocellulose membranes were developed for potential application in artificial kidney systems. By leveraging advances in cellulose modification and processing, these membranes are designed to enhance permeability, selectivity, and antifouling performance. After modifying cellulose through TEMPO oxidation, the ionic liquid 1-ethyl-3-methylimidazolium acetate (EMIMAc) was employed to cast nanocellulose membranes. Three cosolvents, dimethyl sulfoxide (DMSO), dimethylacetamide (DMAc), and N-methyl-2-pyrrolidone (NMP), were added to improve membrane properties and performance during phase-inversion synthesis. Comprehensive characterization was performed using viscosity measurements, scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). These cosolvents were further evaluated for their effect on membrane tensile strength, porosity, pore size, flux, and rejection of bovine serum albumin (BSA) and urea. Additionally, membrane performance was assessed in an ultrafiltration setup using whole blood. Performance parameters, including water flux, permeate blood flux, protein rejection, and urea rejection were evaluated. Chemical changes to the surface due to filtration were evaluated using Fourier Transform Infrared Spectroscopy (FTIR). Cosolvent addition significantly reduced dope polymer solution viscosity relative to the control, with DMAc producing the greatest reduction. SEM analysis revealed that each cosolvent produced a morphologically distinct membrane surface. XRD results showed that TEMPO oxidation slightly reduced the crystallinity of the modified nanocellulose relative to microcrystalline cellulose. TGA demonstrated that membrane thermal stability was lower than that of the raw materials, consistent with structural reorganization induced by ionic-liquid dissolution and regeneration. Cosolvents also significantly impacted membrane mechanics, with DMAc promoting rigid structures, DMSO yielding strong, ductile membranes, and NMP exhibiting intermediate properties. Membranes containing pure EMIMAc were mechanically weaker. This research also highlights an inverse relationship between porosity and pore radius, as evidenced by performance data showing that the denser DMSO membrane displayed lower water permeability. TMNC membranes demonstrated a performance that is comparable with established hemodialysis benchmarks, combining adequate protein retention with promising urea rejection under physiologically relevant conditions. These findings support the potential of TMNC membranes as sustainable alternatives for renal replacement therapy. Key Words: Kidney diseases, membrane performance, ionic liquid, cosolvent, nanocellulose

Download

Share

COinS