Fabrication of visible light-excited photocatalytic TiO2 nanocomposite membranes for removal of organic pollutants and pathogenic microorganisms

点击翻译按钮获取中文摘要

While most Canadians enjoy access to treated water, many First Nations and other remote and rural communities still face challenges with accessing clean drinking water. Frequently, such waters are contaminated with agrichemicals and sewage, providing a nutrient-rich medium for the growth of microorganisms posing a huge risk to human health. Development of cost-effective water treatment devices deployable off the electrical grid would, in light of water treatment needs globally, be highly desirable. Membrane technologies have been extensively ultilized in drinking water treatment; however, biofouling and high operating costs remain significant barriers for implementation. TiO2 nanocomposite membranes augmented with a variety of metallic and non-metallic materials can broaden the spectrum of visible light harnessed to drive photocatalytic degradation of organic contaminants and pathogenic microorganisms; such a system will be a simple but cost-effective means of treating water. ******Currently, there are two strategies for synthesis of visible light-excited TiO2 nanomaterials. The first is to couple TiO2 to other visible light sensitized nanomaterials such as CdS NPs, noble metal nanoparticles (i.e. AgNPs and AuNPs), and dye molecules, to narrow their band gap; however, all published work has been for TiO2 nanoparticles, with no work completed with TiO2 nanowires. These nanowire membranes demonstrated distinct advantages over traditional TiO2 NP approaches, where additional energy is consumed in recycling the nanoparticles, which due to post-treatment removal constraints, may themselves contaminate the final treated water. Another strategy is doping with metallic (Fe, Mo, Ru, Os, Re, V, and Rh) or non-metallic elements (C, S, N, I) during the synthesis of TiO2 nanowires, but the efficiency of this approach is yet to be proven. For the removal of environmental contaminants or pathogenic microorganisms, only initial forays were taken to evaluate anti-microbial and anti-viral attenuation with UV light.******We expect to develop an efficient and effective "green" clean technology (based on doped TiO2 NWs and TiO2 composites with gold and silver nanowires, carbon nanomaterials, LDH) using solar light as the energy source. We further propose the development of an integrated water treatment device, suitable for single family use, in both urban and remote low-resource areas. To date, our group has considerable experience fabricating and evaluating the efficacy of TiO2 membranes towards the degradation of organic contaminants under UV. In addition, a mechanistic study on TiO2 NPs interaction with biomolecules (such as DNA) has been performed, providing new insight into how TiO2 interacts with bio-systems. This knowledge can be transferred to fabricate DNA-TiO2 nanomembranes for pollutant concentration and removal. *****************