Photochemistry "green": Development of transition metal complexes for activation of luminescent singlet oxygen and its application in the disinfection of water contaminated with pathogenic microorganisms (Escherichia coli and Enterococcus faecalis)
In this project we intend to develop luminescent transition metals to act as photocatalysts for disinfection of water contaminated with pathogenic microorganisms. ¬The system was planned to work in rural and/or in small communities of poor sanitation, where lack of infrastructure, funding for operating expenses, plus the lack of training of users limit the use of conventional technologies such as chlorination, ozone, UV radiation. Considering these conditions, we propose a self-sustaining system which uses only water and sunlight as energy source and a luminescent transition metal complex to activate the singlet molecular oxygen, 1O2, formation. Upon exposure to visible light, the fotosensitizer catalyzes the production of singlet oxygen from the dissolved oxygen in the water. Singlet oxygen is a potent disinfectant, known to disable a wide range of bacteria and viruses. It is noteworthy that 1O2 presents high reactivity and short lifetime (a few microseconds in water, which in no way represents any risk of toxicity except for those microorganisms in the immediate vicinity to the singlet oxygen photogeneration. We intend to prepare a series of luminescent complexes of the type [Ru(a-diimine)2(phen-per)3]2+ and evaluate their spectroscopic properties, electrochemical, photochemical and photophysical properties in aqueous solution and in polymer films (silicon, nafion and cellulose) in the presence and absence of 3O2. Moreover, because these compounds are easy to synthesize and are thermally and chemically stable, exhibits intense luminescence in the visible region, and are ease of obtaining derivatives and are immobilized on polymeric films. The practical application of the photocatalyst on the treatment of water contaminated with the microorganism E. Coli will also be investigated. The results of this trial will be compared with the SODIS desinfection method in the same experimental conditions. We expected that this research opens unew perspectives for the purification of water for residential use contaminated with pathogenic microorganisms.
News published in Agência FAPESP Newsletter about the scholarship: