Combination of pulsed corona discharge plasma and gamma-Al 2 O 3 -supported catalysts for polycyclic aromatic hydrocarbon removal in soil

Performance and potential mechanism of transformation of polycyclic aromatic hydrocarbons (PAHs) on various iron oxides

The abiotic transformation of polycyclic aromatic hydrocarbons (PAHs) is significantly impacted by soil components, especially inorganic redox species like iron oxides. In this study, the catalytic activities of three types of iron oxides in PAHs degradation without light irradiation were evaluated using a combination of experimental techniques. The results showed that α-Fe₂O₃ possessed the highest transformation rate for anthracene (ANT), with a reaction rate constant (K_obs) up to 0.28 d^-1, followed by Fe₃O₄ (K_obs = 0.06 d^-1) and α-FeOOH (K_obs = 0.06 d^-1). X-ray photoelectron spectroscopy (XPS) characterization suggested that α-Fe₂O₃ had the highest oxygen vacancy concentration, which was conducive to the adsorption of O₂ by α-Fe₂O₃, providing sufficient adsorbed oxygen species. Oxygen vacancy contributed to the exposure of Fe(III), and accordingly, more active sites were created that were responsible for ANT degradation. According to these results, two possible pathways for the degradation of PAHs on iron oxides can be concluded: (1) direct oxidation by Fe(III) and (2) oxidation by the O₂^•- generated onto oxygen vacancies. This study provides significant insights into the environmental fate of PAHs on iron oxides, and raises the possibility that iron oxides may be used as catalytic materials in the remediation PAHs-contaminated soil.

AOPs-based remediation of petroleum hydrocarbons-contaminated soils: Efficiency, influencing factors and environmental impacts

Petroleum hydrocarbons are a class of anthropogenic compounds including alkanes, aromatic hydrocarbons, resins, asphaltenes and other organic matters, and soil pollution caused by petroleum hydrocarbons has drawn increasing interest in recent years. Multiple advanced oxidation processes (AOPs) are emerging to remediate petroleum hydrocarbons-contaminated soils, while very few studies have focused on the features of AOPs applied in soils. This review aims to provide an updated overview of the state of the science about the efficiency, influencing factors and environmental implications of AOPs. The key findings from this review include: 1) cyclodextrin and its derivatives can be used to synthesize targeting reagents; 2) soil organic matter (SOM), glucose and cement can activate persulfate; 3) SOM affects redox circumstance in soil and could be further developed for enhancing the catalysis effect of transition metals; 4) non-thermal plasma and wet oxidation are promising methods of AOPs to remove petroleum hydrocarbons from soil; 5) the occurrence, fate, and transformation of intermediates during the degradation of petroleum hydrocarbons in soil should be considered more. Overall, this review reveals an urgent need to develop the cost-effective remedial strategies for petroleum hydrocarbons contaminated soils, and to advance our knowledge on the generation, transport and propagation of radicals in soils.

Reclamation of DPK hydrocarbon polluted agricultural soil using a selected bulking agent

In the present study, laboratory scale bioremediation of dual purpose kerosene (DPK) hydrocarbon polluted soil using bulking agent (saw dust) was carried out. The effect of different parameters such as total petroleum hydrocarbon (TPH), dehydrogenase activity (DHase) and pH on bioremediation performance were evaluated. Studied parameters such as microbial dynamics, percentage degradation (95.20%), DHase (8.20 ± 0.43) were found to be higher in saw dust amended system and significantly differed with control at p < 0.05. Experimental data adequately fitted the first order kinetic thus, generated r(2) values (0.966), first order degradation constant (0.659 d(-1)), and degradation half-life t1/2 = ln2/k (1.05 d). Micrococcus luteus, Bacillus sp., Rhizopus arrhizus and Aspergillus sp. were isolated from the study. The use of saw dust as bulking agent greatly increased biodegradation rate and resulted in effective DPK hydrocarbon clean up. Therefore, saw dust could serve as an effective biostimulant towards improved bioremediation of hydrocarbon polluted environment.