Synthesis, properties, and applications of an anionic-nonionic Gemini surfactant for highly efficient remediation of perchloroethylene-contaminated aquifers

Monomeric surfactants are currently used for the remediation of dense non-aqueous phase liquid-contaminated groundwater. However, they result in low remediation efficiency because of their high adsorption loss and low temperature and salt resistance. In this study, a novel and green Gemini surfactant, SNE(10)SID (sodium nonylphenol ethoxylate (10) sulfoitaconate diester), was synthesized for subsurface environment characteristics through esterification and sulfonation. This surfactant consisted of two long and straight hydrophobic chains, two selfsame non-ionic portions, and two anionic moieties covalently connected to each other by an itaconic acid spacer. The critical micelle concentration was ~10(-4) M. The interfacial tension between SNE(10)SID and perchloroethylene (PCE) was significantly low, and the value was found to be 1.0 mN/m. SNE(10)SID exhibited excellent activity under conditions of low temperature and in high salt systems. The solubility of PCE was up to 8863 mg/L in a 4 wt% SNE(10)SID solution, which was two orders of magnitude higher than the solubility recorded in pure water. SNE(10)SID exhibited a low adsorption loss (only 0.8 mg/g at a concentration of 2 g/L in medium sand). The PCE desorption ability of the surfactant was far significantly higher than the PCE desorption abilities of other monomeric surfactants in various aquifer media. Under conditions of dynamic flushing, the low viscosity SNE(10)SID solution exhibited excellent remediation ability when PCE-contaminated simulated aquifers were used for the studies. The total PCE removal rate reached was 87.5% after the flushing of 10 pore volumes. These results revealed that SNE(10)SID was an excellent surfactant that could be used to realize efficient aquifer remediation.

Automated summary

In this study, a novel and green Gemini surfactant, SNE(10)SID, was synthesized for the remediation of dense non-aqueous phase liquid-contaminated groundwater. The surfactant exhibited excellent activity under low temperature and high salt conditions, and showed a low adsorption loss. It also demonstrated a significantly higher PCE desorption ability compared to other monomeric surfactants. The total PCE removal rate reached 87.5% after 10 pore volumes of flushing.