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PROPERTIES OF FOOD GRADE (EDIBLE) SURFACTANTS AFFECTING SUBSURFACE REMEDIATION OF CHLORINATED SOLVENTS
Citation:
Shiau, B. J., D. A. Sabatini, AND J. H. Harwell. PROPERTIES OF FOOD GRADE (EDIBLE) SURFACTANTS AFFECTING SUBSURFACE REMEDIATION OF CHLORINATED SOLVENTS. ENVIRONMENTAL SCIENCE & TECHNOLOGY 29(12):2929-2935, (1995).
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Description:
In this research, several food grade (edible) surfactants are systematically evaluated for various loss mechanisms: precipitation, adsorption, and coacervation (for nonionic surfactants). Cloud points for the polyethoxylate sorbitan (T-MAZ) surfactants are much higher than aquifer temperatures, and the effects on surfactant losses should be minimum. Precipitation boundaries of bis(2-ethylhexyl) sodium sulfo- succinate (AOT) and sodium mono- and dimethylnaphthalene sulfonate (SMDNS) were established. Existing precipitation models successfully predicted precipitation boundaries for SMDNS but showed minor deviations for AOT results. AOT was more susceptible to precipitation than the cosurfactant evaluated, SMDNS. Nonionic polyethoxylate (POE = 20) sorbitan monostearate (T-MAZ-60) and POE(80) sorbitan monolaurate (T-MAZ-28) formed liquid crystal phases at high surfactant concentrations (>0.5 wt %) while POE(20) sorbitan monolaurate (T-MAZ-20) and POE(20) sorbitan monooleate (T-MAZ-80) remained in aqueous solution at concentrations up to 5 wt %. T-MAZ-60 and T-MAZ-28 also showed a continuous increase of "adsorption" at high surfactant concentrations (likely due to liquid crystal formation). Other surfactants showed Langmuirian-shaped isotherms at high concentration, while the cosurfactant SMDNS experienced negligible adsorption. On a mass basis, the maximum adsorption (
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PROPERTIES OF FOOD GRADE (EDIBLE) SURFACTANTS AFFECTING SUBSURFACE REMEDIATION OF CHLORINATED SOLVENTS
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