ELECTROCHEMISTRY STUDY ON EFFECT OF MICROBIAL SURFACTANT ON DEMULSIFICATION OF CRUDE OIL EMULSION

One kind of microbial surfactant was selected and mixed with three demulsifiers GE 189,XE 120 and XP 120, respectively, to resolved the model crude oil emulsion. The results indicated that the introduction of microbial surfactant could greatly raise the speed and efficiency of water separation from emulsion, especially at lower demulsifier concentrations,the effect of microbial surfactant on water separation from emulsion was more obvious. By means of measurement of interfacial tension, the synergetic effect between demulsifier and microbial surfactant was confirmed. Interfacial film electric capacity ( C m) and film electric resistance ( R m) were measured by electrochemical method, and the mechanism of microbial surfactant on the re solution of model crude oil emulsion was studied. The results showed that no significant effect on C m and R m was observed when only microbial surfactant was used, however, when microbial surfactant was mixed with demulsifier,the increase of C m and the decrease of R m with time were more remarkable than those only demulsifier was used, demonstrating a synergetic effect between microbial surfactant and the demulsifier. In addition, the rapid increase of C m and the rapid decrease of R m were closely related to the increase of water separation speed from model crude oil emulsion as a result of the addition of the microbial surfactant, which showed that the electrochemical method was feasible in studying demulsification mechanism.