Biosurfactant solubilization of PAHS

A biosurfactant produced by Rhodococcus strain H13-A and a commonly used sy nthetic surfactant, Tween-80 (polyoxyethylene sorbitan monooleate), are com pared for their effectiveness in enhancing the aqueous concentrations of po lycyclic aromatic hydrocarbons (PAHs) from a complex organic phase (crude o il). The focus of this research is on the highly toxic and regulated consti tuents of weathered crude oil, namely the three- and four-ring aromatics an d the methyl-substituted derivatives. The micellar-enhanced "solubility" wa s monitored in the presence of surfactants when compared to solubility in t he absence of surfactants. The phenanthrenes, fluorenes, pyrenes, and chrys enes showed statistically significant increases in their aqueous-plus-micel lar-phase concentrations in the presence of surfactants compared to the con trols. Moreover, the enhanced PAH concentrations ranged from 2.2 times to m ore than 35 times for the biosurfactant treatment compared to the synthetic surfactant treatment. In the biosurfactant treatment, the enhancement in " solubility" was also higher for the methyl-substituted aromatics when compa red to their parent compounds, although these substituted compounds are nat urally less soluble than the parent. The biological surfactant was, therefo re, more effective than its synthetic counterpart in solubilizing these com pounds from a complex mixture to an aqueous solution.