Singlet Oxygen Photosensitizing Materials for Point-of-Use Water Disinfection with Solar Reactors

Singlet molecular oxygen (O-1(2)) is a potent electrophile and a strong oxidizing agent and can be easily generated by photosensitization via illumination of appropriate dyes with visible light. This short-lived reactive oxygen species is able to photooxidize many electron-rich organic compounds and, therefore, O-1(2) can damage many cellular components, such as membrane lipids, proteins and DNA, causing the photoinactivation of microorganisms in water. This Review summarises the most relevant work to date on solar water disinfection by photocatalytic O-1(2) production, using photosensitizing materials suitable for their use in solar reactors for water treatment. The prototypes were equipped with compound parabolic collectors of sunlight and designed for point-of-use water treatment. The choice of the type of dye (Ru-II complexes or fullerenes) and polymeric support for the preparation of the O-1(2) photosensitizing material, as well as the most important photophysical and operational parameters to be optimized to achieve efficient water disinfection with solar reactors, will be discussed.