Physicochemical Remediation Of Petroleum-contaminated Soil

Soil, which is one of the most important environmental elements, is the home of all terrestrial organisms and the foundation of biological diversity. With the development of oil industry, the contamination of soils by crude oil has become a widespread environmental problem, and the removal of petroleum hydrocarbons from soil is becoming a major concern. As an important scientific and technological area, remediation of contaminated soils draws more and more attentions. Soil washing as a commonly-used method for oil removal has been studied and employed extensively in the field of soil remediation. The mechanisms of surfactant promoted oil to transfer from soil to water have been proposed to occur in two steps:mobilization and solubilization.Oil-contaminated soil washed with the synergistic of SDS and OP-10by ultrasound and oscillation were conducted and the effect of influencing factors on the removal of oil was investigated. The oil components in soil and the mechanisms were analyzed by means of three-dimensional excitation emission matrix fluorescence spectrum.The results showed that the solubility enhancement efficiency by ultrasound was better than oscillation. The effect of OP-10was better than SDS. The synergistic of SDS and OP-10was better than the single one at comparable surfactant concentration. The adsorbing capacity of OP-10has a positive influence on the adsorption time and equilibrium concentration. The isotherm can be described with Langmuir model. The removal efficiency washed by ultrasound was better than oscillation. The oscillation was helpful to remove the light composition of oil (LCO) and low carbon compounds, while the ultrasound was helpful to remove the heavy composition of oil (HCO) and polycyclic aromatic hydrocarbon (PAH). The influencing factors such as surfactant concentration, pH, the ratio of liquid to solid, temperature, washing time had a positive influence on oil remove. The optimum condition was obtained:Surfactant concentration5g/L, pH7, liquid-solid ratio20mL/g, temperature25℃, the time of washing respectively oscillation30min, oscillation2h. High concentration, liquid-solid ratio and temperature were helpful to remove HCO and the aromatic compound of above tricyclic (ACT). Basic compounds addition to the solution was helpful to remove LCO, and pentacyclic aromatic hydrocarbons(PeAHs). Sufficient washing time was help to remove HCO and ACT. The addition of CaC2, KCl and NH4Cl to the solution reduced the removal rate, while Na2CO3and Na2SiO3increased the rate. Na2CO3was helpful to remove the HCO and monocyclic and bicyclic aromatic hydrocarbons. Na2SiO3was helpful to remove the HCO and ACT. There were no changes when added NaCl to the solution.