Surfactant Enhanced Desorption of TNT from Soil

Surfactant enhanced desorption of 2,4,6-trinitrotoluene (TNT) from contaminated soils at a military site was investigated. Anionic (SDS and DOWFAX 8390), cationic (CTAC and CTAB), and nonionic (Tween 80 and Brij 35) surfactants were first tested at concentrations ranging from 0.1 to 1%. The anionic and nonionic surfactants were further tested at concentrations of up to 10%. Anionic surfactants, particularly SDS, provided the best desorption of TNT from the soil. There was not any increase in TNT desorption for both the nonionics and cationics at concentrations ranging between 0.1 to 1% and the extent of desorption was found to be lower than the TNT desorption only by water. The competition of the negatively charged soil surfaces for the positively charged cationics and the neutral nonionic surfactants may constitute the underlying reason. TNT was significantly desorbed when the concentrations of Tween 80, DOWFAX 80 and SDS were increased up to 10%.