The Degradation Of Polychlorinated Biphenyls In Soil By Electro-Fenton Process

Polychlorinated biphenyls (PCBs) are one of the most attention kinds of persistent organic pollutants currently, which can cause cancer or harmful effects to human skin, liver and other organs. Polychlorinated biphenyls have the characteristics of persistent, semi-volatile, bioaccumulation and high toxic, which make it difficult to be degraded in the environment, also PCBs generally have higher sediment-water partition coefficient, so most of the PCBs would eventually accumulate in soils and sediments. Thus, the remediation of PCBs-contaminated soils will have some practical significance. This paper studies the remediation of PCBs contaminated soils by electro-Fenton, and has achieved good results. The main contents of the paper are as follows:Study on the remediation of PCBs-contaminated soils by electrolysis process and electro-Fenton process. Under the same process conditions, the removal rate is only9.82%by electrolysis, but the electro-Fenton process reached45.70%, it proved electro-Fenton process superior to electrolysis.Study on the influence factors of the degradation of PCBs-contaminated soils by electro-Fenton. The main influence factors taking into account include the voltage, pH value H2O2dosage, electrolyte dosage and electrode space. The reaction method are to take200g soil sample into electrolysis apparatus, which PCB52concentration in soil is8.72mg·kg-’, regulate the electrolysis voltage is0.65V·cm-2·kg-1, add the dosage of H2O222.2g·kg-1, and the amount of electrolyte NaCl40g·kg-1, electrode space6cm, and the reaction time is120min, then determination of the PCB52in soil which treated by electro-Fenton, under the experimental conditions, it obtained the removal rate of PCB52reached71%.Studied the kinetics of degradation of PCBs-contaminated soil by electro-Fenton process, with the optimum conditions, the dynamic results indicate that the activation energy was2.642×104J, the pre-exponential factor was397.82mol-1·s-1. Therefore, the degradation kinetics equation for PCB52contaminated soil by electro-Fenton process follows:Study on the degradation mechanism of PCB52contaminated water byelectro-Fenton process.The results show that the dechlorination of PCB52may generate two main intermediate products under the experimental conditions.