Remediation of PAH-Contaminated Soil by Combining Surfactant Enhanced Soil Washing and Iron-Activated Persulfate Oxidation Process

There is increasing concern regarding soils contaminated with polycyclic aromatic hydrocarbons (PAHs). In the present study, the remediation of soil spiked with PAHs was explored by the combination of soil washing with sodium dodecyl sulfate (SDS) and subsequent oxidation through persulfate (PS) activated by Fe(2+), nanoscale zero-valent iron (nZVI), and SiO(2)-coated nZVI (SiO(2)/nZVI). Results demonstrated that the removal of phenanthrene (PHE), fluoranthene (FLU), and pyrene (PYR) by SDS is an efficient means for soil decontamination. At SDS concentration of 20 g/L, the removal efficiencies of PHE, PYR, and FLU were 37%, 40%, and 44%, respectively. For the degradation of PAHs and SDS in the soil washing effluents, the efficiencies of PS activated with SiO(2)/nZVI were not significantly different from those of PS activated with nZVI and Fe(2+) (p > 0.05). In practice, SiO(2)/nZVI is more preferable due to the improved antioxidation and dispersibility. At the dosage of 2 g/L (in the amount of iron) of SiO(2)/nZVI, the removal efficiencies of PHE, FLU, PYR, and SDS within 30 min of treatment were 75%, 85%, 87%, and 34%, respectively. The degradation of SDS was much lower than those of PAHs, which facilitated the recycle of SDS. Our findings suggest that PS activated with SiO(2)/nZVI is a promising method for the treatment of soil washing effluents containing SDS and PAHs.