Photochemical behavior of benzo[a]pyrene on soil surfaces under UV light irradiation

The rates of photodegradation and photocatalysis of benzoa]pyrene (BaP) on soil surfaces under UV light have been studied. Different parameters such as temperature, soil particle sizes, and soil depth responsible for photodegradation, catalyst loads and wavelength of UV irradiation blamed for photocatalysis have been monitored. The results obtained indicated that BaP photodegradation follows pseudo-first-order kinetics. BaP photodegradation was the fastest at 30°C. The rates of BaP photodegradation at different soil particle size followed the order: less than 1 mm>less than 0.45 mm>less than 0.25 mm. When the soil depth increased from 1 mm to 4 mm, the half-life increased from 13.23 d to 17.73 d. The additions of TiO₂ or Fe₂O₃ accelerated the photodegradation of BaP, and the photocatalysis of BaP follows pseudo-first-order kinetics. Changes in catalyst loads of TiO₂ (0.5%, 1%, 2%, and 3% (wt)) or Fe₂O₃ (2%, 5%, 7%, and 10% (wt)) did not significantly affect the degradation rates. Both BaP photocatalysis in the presence of TiO₂ and Fe₂O₃ were the fastest at 254 nm UV irradiation.