A Low-Foaming and Biodegradable Surfactant as a Soil-Flushing Agent for Diesel-Contaminated Soil

Abstract

A novel low-foaming and biodegradable surfactant, consisting of a nonionic head and acyl tail, was synthesized by the base-catalyzed additions of ethylene oxide and propylene oxide to oleic acid. The structure of the new surfactant was elucidated by H-1- and C-13 NMR and FT-IR spectroscopies. Measured surface tension was approximately 35.1mN/m, with a critical micelle concentration (CMC) of 0.026mM. Both the viscosity and the foaming tendency were relatively low compared to the reported values of similar surfactants. These properties make this surfactant suitable as a cleaning agent for the purpose of remediation of diesel-contaminated soils via soil-flushing. Moreover, the biodegradability test showed that it was nearly completely removed (more than 95%) after seven days, suggesting it is indeed an environmentally-friendly detergent which is an important trait for any remediation reagents. Feasibility tests using diesel-contaminated soils demonstrated its superb potential as a soil-flushing agent to the level comparable to nonionic commercial products.