Category: Student Competition
The need for disinfection of microorganisms and degradation of emerging contaminants from water requires the development of new, efficient and cost effective techniques that have no undesired consequences in traditional water treatment technologies applicable in both developing and developed countries. Hence, experiments are being undertaken to investigate decontamination of pathogens and pharmaceuticals: (a) determination of pathogen disinfection under different solar conditions (e.g. sunlight, short and long wave UV irradiation), (b) quantification of reactive oxygen species production with optimization and reuse of photocatalysts (e.g. photosensitizers and core-shell nanoparticles) and (c) combined disinfection of E.Coli and other pathogens with degradation of pharmaceuticals. Organic photosensitizers were tested and magnetic/TiO2 core-shell nanoparticles were synthesized as bimodal catalysts for water purification. Magnetic nanoparticles can induce hyperthermic effects on microorganisms. Preliminary experiments using an induction heater showed temperature increase up to 4.5° C due to the presence of magnetic nanoparticles. The nanoparticles can be recovered after use and can have limited toxicity concerns. The materials being tested are riboflavin and vitaminK3 (photosensitizers), as well as titanium dioxide (TiO2) and synthesized magnetic/TiO2 core-shell nanoparticles (e.g. Fe3O4 nanoparticles, cobalt nanoparticles and nickel nanoparticles each coated in TiO2 shell). UV experiments with the natural photosensitizer vitaminK3 showed significant potential in achieving complete disinfection of E.coli under UV–C exposure at an intensity of 0.1microWatt/cm2. VitaminK3 was able to disinfect E. coli completely within 4 hours at 0.25 mM concentrations. TiO2 coated Fe3O4 nanoparticles showed promising results in disinfection of E.coli and degradation of methylene blue (MB) from solution, which indicates that the recoverable magnetic/TiO2 core-shell nanoparticles could be effective for decontamination.