Washing of soil contaminated with PAHs and heavy petroleum fractions using two nonionic [correction] and one ionic surfactant: effect of salt addition.

The aim of this work was to select the surfactant for washing an aged soil contaminated with PAHs and heavy hydrocarbons fraction, between two anionic and one ionic surfactant. The effect of the addition of salt when washing with the ionic surfactant was evaluated. Results of this work indicated the following. Soil contaminants concentration as g TPH kg soil(-1) was 17,200 mg kg(-1). All washing performances were dependent on the type of surfactant and applied doses. In general, best removal efficiencies were obtained with TW80 (59.57%), followed very near by E600 (57.67%), and at the en by SDS (39.0%), in comparison to the blank assessment (only water), where removal efficiency was about 12%. These removal efficiencies were correlated to the MW, CMC, and HLB values of every surfactant. SDS efficiencies were quite enhanced by the addition of 1% (60.36% removal efficiency) and 2% (70.28% removal efficiency) of NaCl. Its seems that there exist two reasons for this phenomena i.e., the diminution in the real value of SDS CMC (as reported by many authors) and, the capabilities of NaCl solutions to dissolve higher amounts of hydrocarbons than only tap water.