Degradation of polycyclic aromatic hydrocarbons in oil deodorizer distillates: Kinetics, degradation product identification and toxicity

Polycyclic aromatic hydrocarbons (PAHs) with strong carcinogenicity can cause great threat to human health. However, limited research has focused on the degradation of PAHs in oil deodorizer distillates (ODDs). In this study, E. coli expressing plasmid PodAB were applied in ODD samples to degrade PAHs and compared with white rot fungi (WRF). Prediction model for reactive sites of PAHs and the toxicity of degradation products were developed using density functional theory (DFT) calculations and quantitative structure-activity relationship (QSAR), respectively. The results indicated that the degradation rate of PAHs in ODD reached up to 59.28% using E. coli with the co-expression of pBRCD, which provided the electron carrier. The prediction results using nucleophilic index was consistent with the identification results of GC-MS, which may be more suitable for predicting the PAH oxidation products. Moreover, the R2 of developed QSAR reached 0.8976 for the correlation coefficient between predicted and observed toxicity value, which can be applied to predict the toxicity of degradation products. This work proposes a potential tool for PAH removal in ODD as well as a simple method for predicting PAH oxidation products as well as their toxicity.