Environmental remediation of petroleum-hydrocarbon-contaminated Avu mechanic village soil using green-synthesized iron oxide nanoparticles: Advance remediation technology

• The leaf extract acted as a reducing agent for FeONPs. • The FeONPs has the potential to mitigate pH-contaminated soil. • The FeONPs significantly degraded the persistent PAHs in the soil samples. • The effectiveness of FeONPs was attributed to its high reactivity. In order to remediate soil contaminated with petroleum hydrocarbons, this study evaluated the potential of iron oxide nanoparticles (FeONPs), synthesized using an aqueous leaf extract of Diodella sarmentosa (sw). The FeONPs were characterized using a high resolution transmission electron microscope (TEM), ultraviolet-visible spectroscope (Uv-vis), Fourier transform infrared spectroscope (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive X-ray spectroscope (EDS). Soil samples (labeled A, B, and C) were collected from four different locations within Avu mechanic village, Nigeria, and then homogenized. The samples were assessed for petroleum hydrocarbon contents and the potential of FeONPs and the bulk FeCl 3 ·6H 2 O to degrade them. Sample A was treated with FeONPs; sample B was treated with the bulk FeCl 3 ·6H 2 O; and sample C, serving as the control, remained untreated. Using gas chromatography coupled to a flame ionization detector (GC-FID), results revealed the concentrations of polyaromatic hydrocarbons (PAHs) and total petroleum hydrocarbons (TPHs) in samples A, B, and C as 35.77 mg/kg and 218.43 mg/L, 500.876 mg/kg and 3838.86 mg/L, and 1163.30 mg/kg and 7358.87 mg/L, respectively. The efficacy of FeONPs in degrading these pollutants more than the bulk compound may have stemmed from their large surface area-to-volume ratio and redox cycling. In view of the higher adjusted R-square values of 49.40 % in PAH as against 34.70 % in TPH, it can be said that both agents (FeCl 3 ·6H 2 O and FeONPs) were more effective in degrading PAH than TPH. On the basis of the findings, it can be concluded that the synthesized-FeONPs degraded the persistent PAH and TPH in the soil samples at an efficiency of 96.92 % and 97.03 %, respectively, when compared to both the bulk FeCl 3 ·6H 2 O and the untreated control.