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

Yanhua Qiu,Helian Li,Zongquan Sun,Meilan Xu

doi:10.3390/ijerph16030441

Abstract

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 Fe2+, nanoscale zero-valent iron (nZVI), and SiO2-coated nZVI (SiO2/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 SiO2/nZVI were not significantly different from those of PS activated with nZVI and Fe2+ (p > 0.05). In practice, SiO2/nZVI is more preferable due to the improved antioxidation and dispersibility. At the dosage of 2 g/L (in the amount of iron) of SiO2/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 SiO2/nZVI is a promising method for the treatment of soil washing effluents containing SDS and PAHs.

Highlights

Polycyclic aromatic hydrocarbons (PAHs) are among the most widespread persistent organic compounds consisting of two or more fused benzene rings
Of PAHs the shape of synthesized and SiO2/nanoscale zero-valent iron (nZVI) particles was spherical with the particle size range in the nanoscale
PAHs can be effectively removed from the soil by soil washing using sodium dodecyl sulfate (SDS) as the surfactant

Summary

Introduction

Polycyclic aromatic hydrocarbons (PAHs) are among the most widespread persistent organic compounds consisting of two or more fused benzene rings. The dominant sources of PAHs in the environment result from the incomplete combustion of organic matter from human activities and natural sources [1]. Due to the characteristics of volatile, low solubility, fat solubility, and high octanol-water partition coefficient, PAHs have a tendency to sorb preferably to soil organic matters. Regarding PAHs removal from contaminated soil or groundwater, there is a wide variety of different techniques that can be applied, such as soil washing with surfactants, chemical oxidation [4,5], and biological and thermal treatments [6]. The removal of PAHs from soil by soil washing is a preferable method because it is a simple process with low cost and mild operation conditions. Sodium dodecyl sulfate (SDS) is widely used in soil washing of organic pollutants

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