Abstract

The growing energy demand leads to the increasing use of petroleum products. Contaminations caused by uncontrolled release of oil bring risks to the environment. In this study, SDS (sodium dodecyl sulfate), AOT (sodium dioctyl sulfosuccinate) and Brij 35 (polyoxyethylene lauryl ether) are the surfactants selected as washing solutions to remove engine oil from an artificially contaminated soil. The soil was formed using clean sand and montmorillonite clay with different ratios. Contaminated soil samples were formed by contaminating the artificial soil with engine oil which was the chosen petroleum product. Both batch and column tests were conducted to investigate the desorption behavior of engine oil from the contaminated soil. The effects of surfactant type, surfactant concentration, soil composition and pH on desorption efficiency of engine oil were examined in batch experiments. The influences of washing volume and flow rate on oil removal efficiency were investigated in column tests. Distilled water was used as the control. The test results indicate that engine oil solubilization increases with the concentration of surfactants above CMC. In the engine oil removal process, surfactant Brij 35 is more effective than surfactants SDS and AOT. Desorption efficiency of the residual engine oil by 0.6% Brij 35 is almost 20 times higher than that by distilled water. With the same washing volume, lower flow rate appears to be more desirable for oil removal from the contaminated soil.