DISTRIBUTION OF NONIONIC SURFACTANT AND PHENANTHRENE IN A SEDIMENT AQUEOUS SYSTEM

A nonionic surfactant, Triton X-100, can act either to enhance or to inhibit phenanthrene sorption from bulk solution onto Lincoln fine sand, depending on the bulk solution surfactant concentration. The distribution of phenanthrene between the sand and the bulk solution is characterized by a partition coefficient that can range in value from less than 0.04 to nearly 10 times that in the absence of surfactant. Sorbed Triton X-100 acts to enhance phenanthrene sorption; not only does the sorbed surfactant directly increase the fractional organic carbon content of the sand but also, on a carbon-normalized basis, the sorbed surfactant is much more effective as a sorbent for phenanthrene than is humic matter. Conversely, Triton X-100 micelles in the bulk solution can greatly enhance the solubilization of phenanthrene and, thus, its desorption from the sand. The balance between surfactant sorption and solubilization effects on the sorption of phenanthrene depends on a number of factors, principally the surfactant concentration and the nature of the solid sorbent. Significant differences in surfactant sorption and its effects on the solubilization of phenanthrene are noted between the low organic carbon sand described here and previously described systems with soils of moderate organic carbon content.