Polycyclic Aromatic Hydrocarbons Separation from Oil-Contaminated Soil Using Supercritical and Subcritical Water

Abstract

Finding an environmental-friend and an affordable method to remove contaminated soils from polycyclic aromatic hydrocarbons (PAHs) is now an attractive field for researchers. PAHs are slightly soluble, thus hardly dissolve in organic compounds, and also biological and chemical degradation processes are not effective to remove them, and the process of extracting these pollutants from soil is a complex process. Super-critical fluid extraction is an innovative process in the field of contaminated soil treatment. Extraction with super-critical fluid is a simple and rapid extraction process which uses supercritical fluids as solvents. This method addresses extraction methods using supercritical and subcritical fluid. The results showed that the supercritical fluid process is very suitable to remove the pollutants such as PHCs, PAHs, PCBs, dioxins, Furans, phenols, Chlorophenols, insecticides, metals and radioactive substances. The supercritical fluid extraction using CO 2 also has the ability to effectively eliminate organic and inorganic compounds present in different contaminated soils. Moreover, this method is more economical for polluted soil treatment compared to other available methods. On the other hand, using this method that uses water is environment-friendly and has lower cost and a higher safety level. Research has also shown that pressurized hot water extraction (SWE) is a better way to extract PAHs. In this method, the extraction process can be improved by combining the SWE process with the oxidation process by adding oxidants such as air, oxygen, hydrogen peroxide, etc.