Application of iron-activated persulfate oxidation for the degradation of PCBs in soil

Abstract

Persulfate oxidation technologies for soil organic pollutants removal have been gained considerable attention due to its high efficiencies and environmental potential. In the present study, the iron compounds (Fe3O4, iron powder, FeSO4, FeCl3) were firstly screened to activate the sodium persulfate (SPS) for polychlorinated biphenyls (PCBs) oxidation in soil. Then the iron-activated persulfate system was optimized and applied to degrade the PCBs in spiked and aged soil. The results indicated that FeSO4 had the best activation for SPS with highest PCBs degradation rates when compared with the other iron compounds. The optimum dosage of SPS concentration and ratio of soil/water was 0.5mol/L and 1:1, respectively, where the degradation of PCBs in soil could reach to about 70.0% after 3d. Soil organic matter indicated significant effects on PCBs degradation. However, the influence of size fractions of agglomerates on the oxidation was not obvious. Application of Fe2+/SPS showed high degradation of PCBs in three aged soil, and the efficiencies increased to 80.5%, 56.3% and 59.1% for three aged soil, respectively, due to the application of FeSO4 in three batches. Results of this study indicated that the application of iron-activated persulfate oxidation is a feasible method to treat PCBs contaminated soil.