Potential use of nonionic surfactants in the biodesulfurization of bunker-C oil

For an efficient operation in biodesulfurization of petroleum and related f uels, the aqueous solubility of insoluble or very slightly soluble sulfur c ompounds contained in the petroleum products has to be increased. In this s tudy, polyoxyethylene nonionic surfactants were used in order to enhance th e aqueous solubility of insoluble or very slightly soluble sulfur compounds contained in the bunker-C oil and the solubilized sulfur contents in the a queous surfactant solutions were measured by X-ray sulfur spectrophotometer . The most hydrophobic surfactant used during this study showed the maximum solubilization capacity for sulfur compounds contained in the bunker-C oil and the solubilization of sulfur compounds was found to increase with temp erature and to be abruptly increased at above 5 wt % surfactant concentrati ons. It was found that Tergitol series surfactants showed higher solubilizi ng capacity than Neodol series surfactants presumably due to the disruption of the regular packing in the hydrocarbon region of the surfactant micella r aggregates and that the addition of a cosurfactant and/or an electrolyte increased the solubilization of sulfur compounds in the bunker-C oil. It wa s also shown that partitioning phenomena were shown to be significant with a hydrophobic surfactant especially at high temperature and pH of the Tergi tol surfactant solution did not affect the solubilization of sulfur compoun ds. The growth of M6 sulfur-reducing bacteria was not greatly affected by t he addition of both nonionic surfactant and cosurfactant. Desulfurization e xperiments with M6 sulfur-reducing bacteria showed that the biodesulfurizat ion rate of bunker-C oil was enhanced with addition of nonionic surfactant and these data suggested the potential applicability of surfactant to the a ctual biodesulfurization system.