مهندسی عمران شریف (Aug 2017)
REMOVAL OF CRUDE OIL FROM SOIL USING ENHANCED ELECTROKINETIC METHOD BY SURFACTANTS
Abstract
Uncontrolled emission of different contaminants in environment, such as soil and groundwater, leads to increasing the contamination and causing risks for the ecosystem and human health. Over the last century, the oil has been one of the energy sources and the raw material for many industries. It must be mentioned that about 0.1\% of its production enters the seas and oceans due to various events and pollutes the water and soil. Among the different methods of soil treatment, Electrokinetic is one of the most widely used methods, especially in the case of fine-grained soils. Due to low solubility of organic contaminants in water, such as oil, application of surfactants is necessary to improve the Electrokinetic method. Surfactants can increase the solubilization of organic compounds by reducing the surface tension and interfacial tension. So, the electroosmosis flow is the most important mechanism of pollutant transport. In this study, treatment of contaminated soils with crude oil, using enhanced Electrokinetic method by surfactants in pilot scale has been investigated. For this purpose, SDS and Saponin were used to remove the oil crude (6000 mg/Kg) from soil. Each test was conducted in cells made of Plexiglas with dimensions of 30*6*5 cm during 7 days. The effect of surfactant concentration (0.1, 0.2, and 0.3 wt \% for SDS and 0.05, 0.1, and 0.2 wt \% for Saponin) and applied voltage gradient (1 and 2 V/cm) to the oil removal from soil were investigated in the experiments. According to results, in the tests conducted with Saponin in 1 V/cm, the maximum removal rate of 18.35\% was obtained in critical concentration (0.1 \%), while using the SDS leads to a removal percentage equaling to 26.14 \% in the highest concentration of SDS (0.3\%). In addition, increasing the applied voltage gradient to 2 V/cm in the tests with critical concentration of surfactants raised the removal efficiency about 4-6\%.
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