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Batch solubilization and washing of chlorobenzene from loess soil by mixed surfactant solutions

Baowei Zhao, Bin Liu, Ruijia Zhu

Surfactant-enhanced remediation (SER) is a promising technology for the removal of hydrophobic organic contaminants in subsurface. Because chlorinated hydrocarbons are prevalent contaminants in soils and ground, much attention has been paid to the ways and techniques to remove them. In this paper, the water solubility enhancements of chlorobenzene by solutions of an anionic surfactant, sodiumdodecyl sulfate (SDS), a nonionic surfactant, Brij 35, and theirmixture SDS-Brij 35 were conducted and compared. Batch washing of chlorobenzene from loess soil was studied using single SDS, Brij 35, themixed SDS-Brij 35, another nonionic surfactant Tween 80 and its mixtures with SDS. It was found that the apparent solubility of chlorobenzene in solutions was linear with the surfactant concentration. The values of themass solubilization ratios (SR)were 0.0728, 0.0921, 0.0961, 0.144 and 0.193 of single SDS, Brij35, 1:3, 1:1 and 3:1 SDS-Brij35 (w/w), respectively. The mixed SDS-Brij 35 exhibited a large solubilization capability for chlorobenzene. In soil-water systems, the water phase concentrations of chlorobenzene increased with the initial concentration of surfactants at large and varied with the kinds of surfactant and ratios. The mixed surfactants at the given mass ratios of anionic to nonionic one exhibited a relative high washing efficiency for chlorobenzene-spiked loess while single ones did poorly. This paper indicated that the mixed anionic-nonionic surfactant could be an alternative ways to clean up the soils and groundwater contaminated by chlorinated solvents.