Light-activated materials for singlet oxygen generation and the degradation of pollutants

Abstract

The research presented in this thesis focuses on light-activated materials that may enhance the treatment of wastewater and further the understanding of wastewater treatment (WWT) technologies. Wastewater disinfection technologies and processes are categorized and discussed by groups, namely conventional, alternatives, and emerging treatments. The pros and cons of all technologies addressed herein will be highlighted, emphasizing their application in WWT and their respective impact on the environment. Specifically, technologies that use advanced oxidative processes (AOPs) have been shown as a promising technology in the disinfection process in WWT and were the motivation behind this research.AOPs, which involve the generation of reactive oxygen species (ROS), are highly potent oxidizing processes and have emerged as an essential class of technologies to accelerate the non-selective oxidation resulting in the inactivation of a wide range of organic pollutants found in wastewater. This thesis will discuss the various types of ROS, materials that generate ROS, and the ROS potential in industrial wastewater treatment. New materials that generate ROS have been incorporated within polymers and have been shown to degrade a model pharmaceutical, namely propranolol, along with several semi-volatile and volatile organic pollutants. Specifically, UV- and visible light-activated membranes were synthesized by the simple method of doping a photosensitizer (PS) into a polyurethane substrate, ClearFlex 50 (CF50). Upon irradiation, these doped membranes generate the ROS singlet oxygen (SO), and through spectrofluorometric and chromatographic measurements, it was determined that propranolol and several pollutants were degraded. This work demonstrates that practical light-activated PS-doped membranes can be used to degrade several pollutants found in wastewater. Furthermore, preliminary studies of PSs that have potential to form metal organic-frameworks were performed and have shown to absorb visible light and generate SO. These results are important for advancing light-activated materials that generate ROS with application in disinfection for WWTs.