Waste Biomass-Extracted Surfactants for Heavy Oil Removal

The potential synergism between biobased surfactants, produced from the alkaline extraction of waste biomass, and a synthetic surfactant was assessed. This synergism was explored in terms of surface and interfacial tension reduction, and the ability of mixtures to remove heavy oil from oil-bearing sand. The waste biomass sources investigated were return activated sludge (RAS) from municipal wastewater from Toronto, Canada, and urban refuse (UR) matter from municipal solid waste compost treatment facilities in Piemonte, Italy. Surfactants from both sources were extracted using alkaline extraction methods. Mixtures of these waste biobased surfactants with the synthetic surfactant, sodium dioctyl sulfosuccinate (AOT), at a total concentration of 1gTOC/L, were able to achieve low interfacial tensions (<1 mN/m) with toluene and hexane, without the addition of electrolytes. The mixtures generally achieved interfacial tensions (IFTs) an order of magnitude below that of the pure biobased surfactant. At an increased total concentration of 10 gTOC/L, an UR extract (FORSUD), mixed at 40% with AOT, reached an ultralow IFT of 0.019 mN/m against hexane, without the need to add salt into the system. Furthermore, the RAS–AOT and UR–AOT mixtures were examined for their use in the removal of heavy oil, bitumen, from contaminated sand. The low IFTs of the mixtures proved to be useful in removing heavy oil (bitumen) from sand particles.