Photodegradation of Estrone in Solar Irradiation

The photodegradation of the steroid estrone (E1), an endocrine disrupting hormone which is commonly released into aquatic environments, was investigated in aqueous solution using natural sunlight (290-700 nm) produced using a solar simulator. The degradation of El was found to follow pseudo-first-order kinetics, with the rate constant decreasing slightly with increasing initial concentration and varying linearly with solar intensity in the region of 25-100 mW cm(-2). The half-life of El using 1 Sun (100 mW cm(-2)) was measured to be 52.50 min in natural conditions. The rate of mineralization based on total organic carbon (TOC) reduction was lower than El degradation, while the TOC of the solution decreased steadily with increased irradiation time. In the presence of humic acid, the photodegradation rate increased significantly, attributed to photosensitization by the reactive species. The solution pH also had a considerable effect on the rate with maximum degradation occurring around neutral pH of 7.