Resource utilization of petroleum-contaminated soil to prepare persulfate activator by ferrate pretreatment and pyrolysis

The petroleum-contaminated soil (PCS) was used as a raw material to prepare carbonized soil (CS) and iron-modified CS (Fe–CS) by limited-oxygen pyrolysis and limited-oxygen pyrolysis with ferrate pretreatment, respectively. The effectiveness and mechanism of CS and Fe–CS as a persulfate (PS) activator to degrade aniline (AN) are investigated. Results demonstrate that PS can be effectively activated by CS and Fe–CS. The degradation efficiencies of AN are 86.45% and 98.58% within 8 h, and 59.67% and 66.30% of the total organic carbon are removed, respectively. After five consecutive reuses, CS and Fe–CS can still reach AN removal rates of 64.78% and 62.47%, respectively, and TOC removal rates of 50.28% and 58.01%, respectively. Fe loading can promote the pyrolysis of CS, increase oxygen-containing groups on the soil surface, and increase the graphitization of carbon in the soil. Radical- and hole-quenching experiments speculate that the predominant reactive species may be holes and 1O2 and that holes are dominant. This research provides an innovative method for the high-value utilization of PCS, and a novel activator for PS to degrade organic pollutants. [Display omitted] •Reuse petroleum-contaminated soil as persulfate activator through pyrolysis.•Co-pyrolysis with ferrate improves the activation efficiency of material.•Clarify the main active species of persulfate activated by carbonized soil.•Obtained persulfate activators can be reused with high efficiency.