Systematic investigation of the synergistic effects of novel biosurfactant ethoxylated phytosterol-alcohol systems on the interfacial tension of a water/model oil system.

Increasing attention has been paid to the potential applications of biodegradable or natural surfactants in various fields, including chemical enhanced oil recovery (EOR), since the use of eco-friendly chemical processes was first proposed. The novel nonionic biosurfactant, ethoxylated phytosterols (BPS-n), was introduced to chemical EOR for the first time. The BPS-n showed a satisfactory ability to reduce the interfacial tension (IFT) between water and a model oil ( n -octane) when the effects of BPS-n concentration, salinity and temperature were investigated. Several typical alcohols have been used as cosurfactants to further reduce the IFT through synergistic effects with BPS-30. Interestingly, there may be a close relationship between the ability to reduce the IFT and the hydrophobic chain length of the alcohol. Based on the adsorption and stereo-hindrance effect, we proposed a reasonable explanation for this relationship. [ABSTRACT FROM AUTHOR]