Bj. Shiau et al., SOLUBILIZATION AND MICROEMULSIFICATION OF CHLORINATED SOLVENTS USING DIRECT FOOD ADDITIVE (EDIBLE) SURFACTANTS, Ground water, 32(4), 1994, pp. 561-569
Surfactant enhanced subsurface remediation is being evaluated as an in
novative technology to expedite contaminant extraction from the subsur
face. Regulatory approval of this technology will likely be enhanced b
y use of surfactants with FDA direct food additive status (''edible''
surfactants). This research establishes edible surfactant systems capa
ble of solubilizing (via micellar partitioning) and microemulsifying (
via middle phase microemulsions) chlorinated solvents (PCE, TCE, and t
rans 1,2-DCE). Micellar partition coefficients with edible surfactants
are observed to be comparable to values previously reported for other
surfactants, with solubilization increasing aqueous concentrations by
one to two orders of magnitude for the chlorinated organics. Middle p
hase microemulsion formation is dependent on surfactant structure and
cosurfactant concentration. Solubility enhancement in the middle phase
systems (microemulsification) is at least one to two orders of magnit
ude higher than solubilization for the same surfactant concentration,
but is much more sensitive to the surfactant system and the contaminan
t. In addition, successful microemulsion formation is seen to be a fun
ction of ground-water temperature and hardness, indicating the need to
consider these and additional factors for successful design and imple
mentation of surfactant enhanced subsurface remediation. This research
thus establishes a variety of edible surfactant systems that can sign
ificantly expedite subsurface remediation of chlorinated solvents, and
illustrates the importance of proper selection and design of surfacta
nt systems.