Effect of parameters on supercritical fluid extraction of nitro-polynuclear aromatic hydrocarbons from sand

The effects of various parameters such as pressure, temperature, modifier identity, and modifier concentration on the supercritical fluid extraction efficiency of different nitro-polynuclear aromatic hydrocarbons (nitro-PAHs) from sand are investigated. It was demonstrated that decreasing the extraction cell dead volume increased the extraction efficiency of the analyte, and addition of a static period to the extraction method improved the extraction efficiency. Also, the results showed that, at the constant temperature, increasing the pressure to 350 atm increased the extraction efficiency of nitro-PAHs, while at the constant pressure, increasing the temperatures to 100 °C had little effect on the extraction efficiency of the analyte. Addition of a modifier such as methanol or toluene to the supercritical CO2 increased the extraction efficiency of the analyte from sand. However, methanol modified CO2 was not as effective as toluene modified CO2 on extraction efficiency of nitro-PAHs from diesel and air particulates. 1-nitropyrene was extracted and identified from diesel and air particulates.