Particle-size-based elution of petroleum hydrocarbon contaminated soil by surfactant mixture

Surfactants are often used to elute the contaminants from soils in order to remediate the polluted soils. However, the heterogeneity of minerals and organic matters with soil particle size may result in adsorption and precipitation of surfactants and affect the distribution of petroleum hydrocarbons (PHCs). In this work, spiked soil samples and surfactant mixture consisting of Tween 80 (TW80) and sodium dodecyl sulfate were prepared. Results showed that the silt-clay-mixture held the high retention capacity of PHCs, and 30% total petroleum hydrocarbons (TPHs) was retained in the soil fraction of ‘<125 μm’ (high concentration), while 70% TPHs (low concentration) was retained in the soil fraction of ‘>125 μm’. TW80 was highly adsorbed on the montmorillonite and aluminosilicates of the soil, and the adsorption of TW80 in surfactant mixture could be relieved at mass ratio of 1:1. This study provides a novel strategy in the elution removal of PHCs from the contaminated soils, in which with the separation of soil particles by the size of 125 μm before elution, as high as 80% PHCs could be eluted from the soil by surfactant mixture.