The Effect of the Mixture of Nonionic Surfactant and Bioactive Agent for Surfactant-enhanced Soil Flushing (SESF) of TCB Contaminated Soil

ABSTRACT The objective of this study was to find the effect of the mixture of the nonionic surfactant and bioactive agent thatsolubilizes trichlorobenzene (TCB) present as a contaminant for surfactant-enhanced soil flushing (SESF). Three differentnonionic surfactants and two different bioactive agents were obtained from four companies. Separate funnel experimentsand shaker table agitation / centrifugation experiments were used for the test. Based on the separate funnel experimentalresults, three suitable mixture agents (APG + OSE, Brij 35 + MOSE, T-Maz 60 + MOSE) were selected. In the shakertable agitation / centrifugation experiments, these three different mixture agents were reduced to one (T-Maz 60 + MOSE). The maximum removal (95%) of TCB was obtained using a mixture of the nonionic surfactant and bioactive agent.Therefore, the used test methods and results can be used for SESF.Key words : SESF, TCB, Nonionic surfactants, Bioactive agents, Maximum removal 1. Introduction Dense non-aqueous phase liquids (DNAPLs), such astrichlorobenezene (TCB), have posed a threat to theenvironment in industrial areas of Korea (Lee et al., 2001;Chung and Lee, 2012). Under normal flow regimes, thisDNAPL phase is immobile and often represents a long-termsource of aquifer contamination as it slowly dissolves intothe groundwater (Deshpande et al., 1999; Wang andMulligan, 2004). Surfactants (surface active agents) and / orbioactive agents may aid in the remediation of subsoil andaquifers contaminated with DNAPL (Lee et al., 2001;Mulligan and Gibbs, 1993). Surfactants and /or bioactiveagents can be used to vastly increase the solubility of theDNAPL in water as well as lower the interfacial tension atthe water- DNAPL interface (Rosen, 1989; Rouse et al.,1993; Wang and Mulligan, 2004). Surfactants can be classified according to the nature ofthe hydrophilic portion of the molecule: anionic, cationic,nonionic, and zwitterionic (Rosen, 1989). Nonionic surfactantsgenerally have smaller critical micelle concentration (CMC)values than ionic surfactants and are known to be goodsolubilizers of hydrophobic substances (Ang and Abdul,1994). Generally, cationic surfactants are not selected inremediation works because of toxicity and strong complexionwith anionic soil mineral surfaces (Paria and Khilar, 2004). Also, anionic surfactants may form precipitates withgroundwater cations, and thereby cause reduction in soilhydraulic conductivity by blocking pores (Rouse et al.,1993; Lee et al., 2002; Chu and Kwan, 2003). Abdul et al. (1990) evaluated the suitability of tensurfactants for washing automatic transmission fluid (ATF)from sand. They measured the surface tension of thesurfactant and also conducted batch tests for solubilizationcapacity. The most effective surfactant was Witconol SN70(alkyl polyoxyethylene glycol, a nonionic surfactant). DOSL (diphenyl oxide disulfonates, an anionic surfactant)was also a good surfactant for the removal of chlorinatedhydrocarbon in the column test and the pilot test (Cort et al.,2002). In another surfactant selection study, using a separatefunnel experiment of solubility, Fountain et al. (1991)evaluated 100 surfactants for washing PCE (tetrachloroe-