Enhanced solubility of petroleum hydrocarbons using biosurfactants

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references.Issued also on microfiche from Lange Micrographics.This research investigation included two similarly-designed experiments. In the first, a biological surfactant produced by Rhodococcus strain H13-A and a commonly-used synthetic surfactant, Tween-80 (polyoxyethylene sorbitan monooleate), were compared for their effectiveness in enhancing the transport of polycyclic aromatic hydrocarbons from a complex organic phase into aqueous solution. In the batch-reactor experiment, each reactor contained a surfactant solution and West Texas Crude oil, while the control reactors contained distilled-deionized water and the crude oil. Using a temporal-monitoring scheme, the reactors were sacrificially sampled to determine the water-accommodated fraction (WAF). The phenanthrenes, fluorenes, pyrenes, and chrysenes showed significant increases in their aqueous-plus-micellar-phase concentrations in the presence of surfactants; the increase was greater for the biosurfactant compared to the synthetic surfactant. The enhancement in "solubility" was also more significant for the highly-substituted aromatics, when compared to their parent compounds. In the second study, the effects of four biosurfactants on the solubility of petroleum saturated hydrocarbons were compared. Rhodococcus species H13-A (glycolipid-producing), Pseudomonas aeruginosa ATCC 9027 (rhamnolipid-producing), Candida bombicola ATCC 22214 (sophorolipid-producing), and Bacillus subtilis ATCC 21332 (surfactin-producing) were compared to a control of distilled-deionized water. The experimental design was similar that of the first study. The Pseudomonas aeruginosa treatment significantly enhanced the solubility of the lower-weight, higher-weight and branched saturated hydrocarbons. The Rhodococcus treatment significantly enhanced the solubility of the low-molecular-weight compounds, but only moderately increased the solubilities of the other saturates. Neither the Candida nor the Bacillus solutions produced any negligible increase in solubility under these laboratory conditions