Enhanced removal efficiency and influencing factors of nitrobenzene in soil by foam flushing

Abstract

Laboratory scale experiments were conducted to investigate the removal efficiency of nitrobenzene in soil by different kinds of flushing liquid. In addition, the influencing factors, such as foam injection rate, foam quality and permeability of medium for the removal efficiency of nitrobenzene in soil were discussed in the paper. The results showed that the residual rates of nitrobenzene in soil were 62.15%, 63.18%, and 2.65%, while the flushing liquid were water, SDS solution, and SDS foam, respectively. The removal efficiency of nitrobenzene was found to be greatly increased by using a foam-enhanced surfactant solution flooding approach, probably because of the reduction in the channeling flow effect. These data demonstrated that by the use of foam, the nitrobenzene recovery efficiency can be significantly improved. Within the scope of the study, the foam quality and foam injection rate has little effect on the total removal efficiency of nitrobenzene in soil. Moreover, the total removal efficiency of nitrobenzene for low permeability (0.1∼0.25mm, 0.25∼0.5mm) is greater than that in high permeability medium. Because of the time necessary for distribution of foam through the soil and desorption process is much longer for soil with a low hydraulic conductivity, this technique is more effective in soil with lower hydraulic conductivity and higher porosity.