Abstract:In view of the high cost and pollution of physical and chemical demulsifiers in the demulsification process of oilfield wastewater, it is necessary to study and synthesize new environmentally friendly demulsifiers. In this paper, a combination of sol-gel and solvothermal method is used to prepare biosurfactant (Biosurfactant, BS) stabilized nano-iron sol materials, to study the optimal BS concentration, and use SEM, XRD, FTIR, laser particle size analyzer, Zeta Potential etc. characterize the BS-stabilized nano-iron sol, and study its morphology, size, phase, functional group, sol stability, particle size distribution and other influencing factors. The demulsification performance of the synthesized nano-iron sol on the oily sewage emulsion prepared by the oil-water mixture on Weizhou Island was investigated. The results showed that after fermentation of the glycolipid biosurfactant T bacteria with a specific medium for 6 days, the supernatant after centrifugation was taken to synthesize iron sol. When the concentration of supernatant was 80 % and 100 %, iron particles with diameters of about 200 nm and 40 – 200 nm could be synthesized, respectively. When the concentration was 60 %, the demulsification effect of nano-iron sol product was the best. At low temperature, it could produce good demulsification effect on the oil-in-water emulsion formed by sodium dodecyl sulfate, and the dehydration rate reached 78 % after 24 h. It shows that the method used in this paper can synthesize BS stable nano-iron sol with good demulsification characteristics. It is suggested that biological metabolites and chemical agents should be combined organically in the future to prepare environmentally friendly composite nano-demulsifiers, while studying its repeated use and other issues.