Smart functionalized catalytic films for drinking water purification

Abstract

This thesis which is entitled "Smart functionalized catalytic films for drinking water purification" is a stepping stone towards overcoming this problem. This thesis evolved around designing new polymers that can be used to make membrane films which can anchor oxidation catalysts such as Fe-(TAML)s, concentrate pollutants and deliver hydrogen peroxide and base to the catalyst centres in a systematic and efficient way so that large volumes of water can be purified without having to contaminate the bulk water solution. In the first chapter green chemistry, oxidation chemistry, the use of hydrogen peroxide chemistry as an oxidant, and common contaminants found in wastewater are discussed, and in addition an overview of homogeneous and heterogeneous catalysts is given. In the second chapter details about the development of the special polymer that was used to form the smart catalytic films (SCFs) in this project is covered. In particular, details of how the polymer was formed, cast, cured, crosslinked and functionalized are discussed as well as the methods used to anchor the catalyst to the polymer film. Details of the mechanism by which the iron-TAML oxidation catalysts operate are presented since most of the subsequent studies involved the use of these compounds. Finally, preliminary studies of the performance of the SCFs in simple catalytic dye bleaching reactions are presented. These studies were carried out so that the most promising SCFs could be selected for further more detailed studies. In the third chapter details of the more comprehensive tests carried out on the selected SCFs is covered. Catalytic oxidation experiments were carried out using water soluble organic dyes as surrogate pollutants with the smart catalytic film used in 3 different configurations; (i) simply suspended in solution in a beaker, (ii) as part of a "U-tube" device that uses the catalytic film to separate the hydrogen peroxide solution from the substrate (pollutant) solution and (iii) a "cross-flow" device that uses the catalytic film to separate the static hydrogen peroxide solution from the flowing substrate solution. In these three configurations the effects of changes to parameters such as pH, types of catalyst, catalyst loading and turbulent flow on the performance of the SCFs were investigated. Finally, in chapter 4, the results of studies aimed at using the smart catalytic films to reduce or completely remove actual contaminants such as 17α-ethynylestradiol (EE2), Bisphenol A (BPA) and Triclosan (TCS) are presented. In these studies the catalytic films were used in the three different configurations detailed above under the semi-optimized conditions that were discussed in chapter 3. In the case of the studies with BPA and EE2, some preliminary tests of the estrogenicity of the oxidation products formed after catalytic oxidative treatment with the SCFs were carried out using a yeast estrogen assay (YES) test to confirm that with the oxidative removal of these compounds from solution there was a corresponding drop in estrogenicity characteristics.