Solar disinfection (SODIS) – the practice of placing water bottles under the sun - has been widely practiced for point-of-use water treatment due to the ubiquity of the active disinfectant (sunlight), its technical simplicity, no-infrastructure requirement, and the low operation cost. Nevertheless, SODIS depends on UV-A radiation and therefore generally suffers from dismal treatment efficiency and excessively long exposure time. Augmenting SODIS with chemicals and catalysts has been attempted, but its practicality has been questioned due to cost and the need to remove catalysts. In addition, there is no indication that the water disinfection has been completed in SODIS scheme, and the users are left with their own best guess on the quality of product water.<br/> <br/>Research in this field should focus on low-cost, readily available, and non-toxic additives to enhance SODIS. Photosensitizers exhibit photon absorption across visible light and can change their electronic spin state through the unique intersystem crossing (ISC) process. Photosensitizers can then transfer energy to molecular oxygen to produce singlet oxygen for microbial inactivation. In this study, we present a photosensitized water disinfection technology that utilizes food dyes – erythrosine and riboflavin – to produce singlet oxygen and to indicate disinfection through photobleaching color change. Our results suggest that upon exposure to simulated sunlight, these food dyes produce singlet oxygen for the effective inactivation of viruses. Singlet oxygen quantum yields were determined through the use of probes, and photobleaching kinetics were determined via UV-VIS spectroscopy. Probe and quencher tests confirm that singlet oxygen is the primary disinfectant produced by these dyes.<br/>

Edible science: Food dye sensitized water disinfection and safety indication

254th National Meeting (2017)

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