GEORGIA INSTITUTE OF TECHNOLOGY

Under the provisions of the regulations for the degree

DOCTOR OF PHILOSOPHY

on Tuesday, June 21, 2016

2:00 PM
in MRDC 3515

will be held the

PTFE DISSERTATION DEFENSE

for

Wail Falath

"Synthesis, Modification And Characterization of Economical, High Performance Reverse Osmosis Membranes"

Committee Members:

Dr. Karl Jacob, MSE (Advisor)

Dr. Hamid Garmestani, MSE
Dr. Youjiang Wang, MSE
Dr. Donggang Yao, MSE
Dr. Kyriaki Kalaitzidou, ME

Abstract:

Water is becoming increasingly scarce as the demand for fresh water continues to increase in a drastic manner. One potential new water resource is desalination of sea and brackish water. Reverse osmosis (RO) membranes desalination is one of the many processes used to obtain potable water fit for human consumption from seawater. Nevertheless, the membranes used in this process are prone to fouling by microorganisms and Chlorine attack.

It has been shown from literature that developing an anti-fouling, Chlorine resistant, highly selective and highly permeable reverse osmosis membranes is a necessity. To develop such membranes, one should improve the hydrophilicity of the membrane surface, reduce its roughness and make the surface negatively charged. The overall goal of this research was the development of high performance reverse osmosis membranes materials with improved permeability, high salt rejection and superior biofouling and Chlorine resistance.

The present research was designed to investigate novel poly (vinyl alcohol) (PVA) RO membranes with various fillers and combinations and their effectiveness as active RO separation layers with improved biofouling and Chlorine resistance. The uniqueness of this work was that the PVA polymer matrix was utilized as an active RO layer without the use of any polymeric or ceramic substrate.

The crosslinked PVA RO membranes incorporated with various fillers were fabricated using dissolution casting method. The fabricated membranes were then characterized and analyzed using various techniques like attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), contact angle measurements, X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM) and mechanical testing. The actual reverse osmosis performance of the membranes, including permeation testing, salt rejection and Chlorine resistance was examined using a reverse osmosis permeation unit.

This study showed that the incorporation of various fillers like Pluronic F127, MWCNTs, Vanillin, Gum Arabic or ZnO NPs into the PVA polymer matrix improved the overall RO performance of the membrane in terms of hydrophilicity, surface roughness, water permeability, salt rejection, Chlorine and biofouling resistance and mechanical strength.   

The outcomes of this study have shown a great promise for the proposed crosslinked PVA membrane as an active RO separation layer without a substrate. The results of this investigation showed that the fabricated RO membranes overcame common PVA drawbacks through appropriate crosslinking and through appropriate selection of fillers.