Photochemical and titanium dioxide (TiO2) photocatalysed degradations of diclofenac and amoxicillin in water, under natural and simulated sunlight, were investigated. Direct photolysis of diclofenac resulted in about 80% degradation after exposure to an irradiation level of 400 W/m2 for 4 h, while in the presence of TiO2, 96% of diclofenac was degraded after the same time period. At the irradiation level of 765 W/m2, 99% of the drug was degraded within 1 h exposure. The efficiency of degradation of diclofenac was thus proportional to the level of simulated irradiation. The use of floating solar reactors has resulted in comparable rate of photodegradation by direct natural sunlight to that achieved by the solar simulator. In contrast, amoxicillin remained photostable under direct photolysis, while degrading significantly in the presence of TiO2
