Efficient catalytic degradation of alkanes in soil by a novel heterogeneous Fenton catalyst of functionalized magnetic biochar

Abstract

In this study, sodium dodecyl sulfate (SDS) functionalized magnetic biochar (SDS-Fe@BC) was successfully prepared. Compared to other traditional heterogeneous Fenton catalysts, more total petroleum hydrocarbons (TPH) (3499.40 mg kg^-1) was adsorbed from soil to the surface of SDS-Fe@BC through hydrophobic interaction between alkyls in alkanes and SDS-Fe@BC, which formed an efficient interface oxidation system. In SDS-Fe@BC-mediated heterogeneous Fenton system, 10,191.41 mg kg^-1 (88.10%) TPH was degraded in the presence of 400 mM H₂O₂, which was 1.38-5.67 folds than that of H₂O₂ alone, Fe²⁺, zero valent iron (ZVI), Fe₃O₄, pristine biochar (BC), and Fe@BC. Moreover, all individual alkanes were efficiently degraded (>75%), and the higher the initial amount of individual alkane, the more the degradative amount in the SDS-Fe@BC/H₂O₂ system. Additionally, TPH degradation was highly related to the mass ratio of SDS/Fe@BC, H₂O₂ concentration, SDS-Fe@BC dosage, and initial pH in the SDS-Fe@BC/H₂O₂ system, and the optimal values were 1:5, 400 mM, 50 mg g^-1, and pH 7, respectively. Radical quenching experiments revealed that hydroxyl radicals (•OH) generated on the surface of SDS-Fe@BC was the dominated reactive oxidative species (ROS) responsible for alkanes degradation. After five cycles, SDS-Fe@BC still remained a high catalytic activity for alkanes degradation (73.21%), showing its excellent reusability. This study proved that the SDS-Fe@BC can be used as a potential heterogeneous Fenton catalyst for petroleum-contaminated soil remediation.

Keywords: Alkanes; Functionalized magnetic biochar; Heterogeneous Fenton; Petroleum hydrocarbons; Soil remediation.