Author ORCID Identifier

https://orcid.org/0000-0003-4579-6201

Date Available

7-31-2025

Year of Publication

2024

Document Type

Doctoral Dissertation

Degree Name

Doctor of Philosophy (PhD)

College

Arts and Sciences

Department/School/Program

Chemistry

Advisor

Isabel C. Escobar

Co-Director of Graduate Studies

Mark Meier

Abstract

According to the Center for disease control (CDC), an estimated 1.7 to 2.2 million persons die from waterborne diseases annually. The majority of individuals dying from diseases resulting from unsafe drinking water, such as diarrhea and gastroenteritis, are children. This has in turn created a global water crisis. Different methods have been developed to treat contaminated water in response to the global water crisis such as adsorption, filtration, ozonolysis, catalysis, etc. Of the methods available, filtration via polymeric membranes has been one of the most successfully applied. A membrane is a thin semi-permeable barrier (often made of a polymer) used to separate differing phases in a media under pressure. Membrane filtration is ideal for water treatment due to high rejection and throughput, as well as ease of integration into other water treatment systems. Unlike other methods of water treatment, membrane filtration can be easily tuned to target specified contaminants at different sizes and pressure levels. However, there are associated disadvantages of membrane filtration such as membrane fouling, which limits its performance and necessitates regular membrane cleaning, and treatment of both the concentrate and cleaning streams that contain rejected contaminants, which ultimately decreases membrane performance and life. Furthermore, due to the accumulation of potentially harmful materials on the membrane during fouling, membranes are often disposed of in landfills after use thus transferring the contaminant from one location to another. This research focused on functionalizing polysulfone (PSf)-based membranes to improve their performance by minimizing fouling and/or destroying accumulated foulants. It investigated the various factors affecting the performance of polymeric membranes such as composition, temperature, pH, charge, porosity, viscosity, additives, co-solvency, functionalization, etc., and incorporated them into synthesizing an optimum membrane composite with minimal environmental impacts. PSf was chosen as the polymer for the base membrane due to its abundant commercial availability, easy processing capabilities, favorable selectivity-permeability characteristics, and stable mechanical, thermal and chemical properties, and then the polymer was optimized for its performance in different applications. Herein, the unique properties of two different polymers, namely poly-ether ether ketone (PEEK) and polysulfone (PSf), have been investigated, optimized, and modified, for the formation of ultrafiltration membranes for use in removal and degradation of organic contaminants present in water. Modification of various dope solutions via formation of composites, copolymerization, use of bioderived solvents, and surface modification produced membranes with desirable physical, mechanical, and chemical properties that are necessary for use in the destruction and removal of targeted organic contaminants such as microcystine-LR and their degradation by-products from water. The performance of the membranes was evaluated in the presence of salts, organic dyes, algal toxins, and disinfectant by-products. The environmental impacts of some of the membranes were analyzed via life cycle analysis.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2024.356

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Available for download on Thursday, July 31, 2025

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