The interaction between surfactants and a dense non-aqueous phase liquid (DNAPL) was investigated. The partitioned amounts of nonionic surfactants to the DNAPL increased with an increase in the surfactant hydrophobicity and a decrease in the interfacial tension. Alcohol enhanced the surfactant loss. With the binary component of the DNAPL, the molar micellar solubilization was not ideal, and the solubilized extent of DNAPL with binary components by the surfactant was larger than with a single component. In surfactant flushing for a DNAPL contaminated sand column, the small amount of partitioned surfactant to the DNAPL facilitated the mobilization of the DNAPL. (C) 2017 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.