UV Assisted Photocatalytic Remediation of Polycyclic Aromatic Hydrocarbons (Pahs) in Sewage Sludge Addition Soils Using Synthesized Nanometer Mixed-crystal TiO2: Experiment and Simulation

Abstract

ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) entering into soils via sewage sludge could be posing arresting environmental risks. Photocatalytic remediation has been considered as a powerful tool of degrading PAHs in soils. In the present study, a synthesized nanometer mixed-crystal TiO2 was employed to investigate its effects on PAHs degradation in soils by Ultra Violet (UV).Two typical substances of PAHs widely detected in sewage sludge (phenanthrene and pyrene), were added into soils from farmland to provide polluted soil for a series of simulated experiments. These polluted soil samples were mixed with five different levels of the synthesized TiO2 (0, 1%, 2%, 3%, and 4%, wet weights) and the decreases of PAHs under different conditions were compared. The results showed that among the five treatments, the activities of the synthesized photocatalysts followed the order of 0<1%<2%<4%<3%, and the 3% of TiO2 addition was determined as the optimum condition. Moreover, it was found that the degradation of PAHs could increase with the increasements of H2O2, photon flux, and humic substances in treated soils. Our findings supports the perspective of using nanometer synthesized mixed-crystal TiO2 in the degradation of PAHs in contaminated soils by sewage sludge addition and provides hints on understanding the mechanism of developing photocatalytic remediation in PAHs-contaminated soils.