Field Studies in Solar Photocatalysis for Detoxification of Organic Chemicals in Water and Effluents

TiO2 — photocatalytic degradation of organic contaminants in water included studies of water samples taken from a heavily polluted well under exposure to natural sunlight; waters from liquid commercial pesticide formulations, simulating treatment of rinse waters of agricultural sprayers; in these studies most compounds were appreciabely degraded within 3.5 h but more complete detoxification required longer exposure. Photocatalytic oxidation of dye chemicals from textile industry resulted in complete degradation of selected azo and thiazine dyes. In the case of dyes the photocatalytic oxidation is accompanied by a reaction of dye sensitization. Enhanced degradation of colourless refractory pollutants has been observed in the combined process. The main advantage of the combined approach is the utilization of visible light for the degradation of refractory organic pollutants, both coloured and colourless, which cannot be photosensitized in the visible region.