Photocatalytic Removal of Petroleum Hydrocarbon Contaminated Soils Using Nanoparticles and UV Light

Soils contaminated with petroleum compounds, especially polycyclic aromatic hydrocarbons (PAH’s), are one of the major environmental problems that threats the ecosystem and human life. This complex mixture of petroleum hydrocarbons is fused and contains various isomers of carbon and hydrogen, which are composed of a double rings or more loops. Today, many well-developed methods have been proposed for the remediation of contaminated soil, which, regardless of the complexity of the process, are very difficult and costly. The aim of this study was to decontaminate polluted soils from pyrene as an index of poly aromatic hydrocarbons (PAH’s). The remediation of PAH compounds like pyrene was carried out by using nano-photocatalysts. In this study, the response surface methodology (RSM) is performed for the formulation of catalyst concentration and UV exposure time. Under laboratory conditions, artificially clean soil samples were sterilized and contaminated with 40 mg/kg pyrene. Then, 5 grams of the soil contaminated with a solution of 40 ppm pyrene (PAH’s compounds) were well mixed with different nano-photocatalyst concentrations of 2, 4, 6, 8, and 10 wt%. of TiO₂, ZnO, and SnO₂. The soil samples were exposed to UV-C light (15 Watt at a wavelength of 254 nm) in a photo-degradation reactor for 10, 15, and 20 hrs of exposure. Under the photo-oxidation reactions, the removal of pyrene from the soil samples was calculated according to a standard method (ASTM D-5520) of fluorescence UV spectroscopy. The results showed that the degradation of pyrene by the mentioned nano-photocatalysts were possible and the highest rate of degradation (71%) was obtained at a TiO₂ catalyst concentration of 10 wt.% during 20 hrs of UV exposure. In this paper, the photocatalytic removal of hydrocarbons was studied by using a nano-photocatalytic degradation process having various factors such as the effect of catalyst type, catalyst concentration, and UV irradiation exposure time. Finally,  the removal of pyrene from soil was determined and the corresponding absorption spectra were presented