Partial substitution of conventional synthetic surfactant by biosurfactant enhances the stability of micro-droplets of crude oil in surfactant solution in flow state and within sub-second period

Microbial lipopeptides have been proposed to adsorb at interface rapidly and have synergistic effect with syn-thetic surfactant, and we assumed that stable droplets of oil would generate and oil-in-water emulsion with good stability would be obtained using the mixture of microbial lipopeptides and synthetic surfactant in short time scale. Here, the interfacial properties of the mixture of microbial lipopeptide and petroleum sulphonates has been evaluated using the coalescence frequency of the micro-droplets of crude oil in surfactant solutions in flow state and within sub-second period based on a microfluidic method. Results showed that partial substitution of pe-troleum sulphonates by lipopeptide enhanced the stability of micro-droplets of crude oil in surfactant solutions. To form stable micro-droplets of crude oil, less lipopeptide/petroleum sulphonates mixture (m:m=1:1) was needed than petroleum sulphonates. Moreover, higher salt tolerance, less demand of alkali, and shorter adsorption time were obtained for lipopeptide/petroleum sulphonates mixture to form stable emulsion comparing with that of individual petroleum sulphonates mixture. The present study provide novel information of lipopeptide/petroleum sulphonates mixture in generating stable crude oil-in-water emulsion at flow state.