Remediation of petroleum-contaminated soil by Fenton oxidation–pyrolysis

Abstract

Petroleum-contaminated soil (PCS) is urgently to be remediated due to its risk to ecological environment and human health. In this study, a Fenton oxidation–pyrolysis strategy was employed to accomplish effective petroleum removal and PCS remediation. The highest total petroleum hydrocarbon removal efficiency could achieve 99.6% after 2 h Fenton oxidation, with H₂O₂/Fe²⁺, 6:1, and pH 3, followed by pyrolysis at 370°C. The organic compositions of the soil after Fenton oxidation, the kinetics and process of the pyrolysis, morphologies and structures of the treated soil, as well as energy consumption and cost savings were comprehensively researched and analyzed. Through the Fenton oxidation–pyrolysis treatment, the macromolecules were effectively degraded and the contents of asphaltenes and resins were significantly reduced in the soil. Graphitized carbon was dominatingly existed after the pyrolysis. A 1.5 order reaction model was proposed to reasonably describe the pyrolysis remediation process of PCS. The Fenton oxidation–pyrolysis treatment can reduce energy consumption and cost compared with pyrolysis alone. This work not only offered an alternative approach of PCS remediation, but also provided theoretical guidance for practical soil remediation.