The superior surface activity and solubilization performance of a novel sugar − based Gemini surfactant for the remediation of PCE − contaminated aquifer

Conventional monomeric surfactants employed in surfactant − enhanced aquifer remediation (SEAR) face significant limitations, including precipitation propensity, substantial adsorption losses, and suboptimal solubilization of dense non − aqueous phase liquids (DNAPLs). This necessitates the development of novel surfactants with enhanced surface activity and solubilization capacity. Accordingly, a novel sugar − based nonionic Gemini surfactant, APG − EGDE, was specifically synthesized for subsurface application. APG − EGDE features hydrophilic groups derived from two glucose molecules, offering high biodegradability and excellent resistance to low temperatures and ionic interference. The hydrophobic groups were comprised of two long and straight hydrocarbon chains, providing a low critical micelle concentration (CMC: 0.07 mmol/L) and reduced surface/interfacial tension (4.0 mN/m with PCE). And the ether bond (C − O − C) acted as a linker group. Remarkably, homogeneous solutions did not precipitate under extreme groundwater environmental conditions such as high salinity (10 % NaCl or CaCl 2 ) and low temperature (<0 ℃). At 1 g/L, the adsorption loss by medium sand of APG − EGDE was minimal, with only 0.0058 mg/g. APG − EGDE exhibited superior PCE solubilization capacity (10052 mg/L at 40 g/L), exceeding conventional surfactants such as SDS and Tween − 80. One − dimensional column flushing confirmed high PCE removal efficiency after 10 pore volumes. These results showed the Gemini surfactant APG − EGDE serving as a superior surfactant alternative for remediating DNAPL − contaminated aquifers.