Ex-situ removal of crude oil from a contaminated soil using Sodium Dodecyl Sulfate (SDS)

Soil is the basic component of environment and the main source of food production and its contamination can cause pose many challenges for humans and other living organisms. Although many studies have been done separately to eliminate organic pollutants such as benzene and phenolic compounds from soil, a few studies yet have been done on the removal of crude oil which contains different types of hydrocarbon compounds from the soil. The aim of this study is to determine the removal of crude oil from the soil and provide a comprehensive model. In this study, the ex-situ soil washing method with surface active agent has been used to remove crude oil from soil. For this purpose, first, the soil was artificially polluted with crude oil and then the effects of various parameters such as surfactant concentration in aqueous solutions, the initial concentration of contaminant in the soil, pH, volume of detergent solution, stirring rate, duration of the process and system temperature were evaluated. The results showed the optimal conditions for the removal of crude oil were concentration of surfactant in aqueous solution of 0.5% (w/w), initial concentration of crude oil of 5% (w/w), detergent solution pH=11, detergent solution volume of 50 ml, stirring rate of 200 rpm, experiment duration of 15 m and temperature of 45 °C. In optimal condition, about 96% of crude oil was removed from the soil. According to the obtained results, surfactants can be used as a proper substance to remove oil contaminants from soil with a good efficiency.