Kinetics Dynamics of Photocatalytic Degradation of PAHs on Soil Surface Using Humic Acid

Polycyclic aromatic hydrocarbons(PAHs) are a group of major contaminants that are ubiquitous in environment due to their toxicity,mutagenicity and carcinogenicity.Effects as well as dynamics of humic acids(HA) and intensity of UV irradiation on PAHs photodegradation with phenanthrene(Phe) and pyrene(Pyr) as target contaminants were studied.Results showed that HA played a sensitivizing role during Phe/Pyr photodegradation,with the process of photodegradation following the first order reaction kinetics model.The photodegradation rate constant of PAHs increased with increasing of the concentration of HA.When HA concentration was 0,10,20,30,40 mg/kg,half-time of Phe was 52.90,47.79,43.86,37.87,34.48 h,and that of Pyr was 45.90,38.50,36.09,30.26,29.74 h.HA not only could efficiently sensitivize the Phe/Pyr photodegradation,but also degrade Phe/Pyr by photooxidation.Rate of photodegradation increased with increasing UV irradiation intensity.The study would provide a reference for further studies on improvement of HA photodegradation PAHs on soil.