Beneficial utilization of derivatives from petroleum-contaminated soil by ferrate-assisted pyrolytic remediation to adsorb heavy metal in wastewater

Abstract

Conventional remediation technologies for petroleum-contaminated soil (PCS) usually consider harmless treatment as the primary goal, ignoring the reutilization value of PCS derivatives; they generally face the dilemma of high cost or low efficiency. In this study, PCS was treated by ferrate-assisted pyrolysis for highly efficient remediation and transformation to Fe-loaded carbonized soil (Fe-CS) as a heavy metal adsorbent. The total petroleum hydrocarbons and dissolved organic matter in the obtained Fe-CS were almost completely removed. When the pyrolysis temperature was 500 °C, retention time was 30 min, and 10 % K2FeO4 was added, The Langmuir model showed that the maximum adsorption capacities of Pb2+ and Cu2+ of Fe-CS were 347.9 and 106.3 mg/g, respectively. The adsorption processes of Pb2+ and Cu2+ onto Fe-CS fit the pseudo-second and pseudo-first kinetic models, respectively. X-ray diffractometer (XRD), Raman spectroscopy, Fourier transform infrared (FTIR), Brunauer–Emmett–Teller (BET), and X-ray photoelectron spectroscopy (XPS) were used to characterize the adsorbent. XPS analysis showed that iron oxide, metal carbonate, and CO on the Fe-CS surface were significantly increased compared with the carbonized soil (CS) obtained by pyrolysis alone. In addition, the BET specific surface area and micropore volume of Fe-CS are higher than those of CS. The chemical specifications of the heavy metals in Fe-CS showed that they are mainly bound to carbonates and iron oxides. This study provides an innovative method for the simultaneous realization of the efficient remediation and high-value reuse of PCS.