腐殖酸光敏化降解土壤中多环芳烃的动力学

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

多环芳烃化合物(PAHs)由于致癌、致畸和致突变而受到广泛关注。实验以多环芳烃菲(Phe)和芘(Pyr)为目标污染物,研究了腐植酸和紫外辐射强度对PAHs光降解动力学的影响,及腐植酸光敏化光降解土壤中PAHs的机制.结果表明,腐殖酸光敏化降解Phe和Pyr符合一级动力方程,随着腐殖酸投加量的增加,Phe和Pyr的动力学常数也逐渐增加,半衰期缩短,在添加0、10、20、30、40 mg/kg腐植酸后,Phe的半衰期分别为52.90、47.79、43.86、37.87、34.48 h,Pyr的半衰期分别为45.90、38.50、36.09、30.26、29.74 h;腐殖酸可以将吸收光能传递给土壤中Phe和Pyr使其发生敏化光解,也可以使Phe和Pyr发生光氧化反应;随着辐射强度的增加,PAH光降解速率增加。该研究为应用腐殖酸光敏化降解土壤中PAHs有机污染物提供了参考依据。

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.