Characterization of a lipopeptide-glycolipid blend biosurfactant and the effect of alcohol cosurfactant

Biosurfactants(BS) produced by Bacillus subtilis THY-8 were extracted and identified as a blend of rhamnolipid,surfactin and fengycin,etc,by MALDI-TOF Mass Spectrometry. The blend BS remained stable when stayed at 70℃ for 5 days;and the surface tension and critical micelle concentration were 27.59 mN/m and 15 mg/L at pH5.5,respectively. When treated by BS,the liquid paraffin was emulsified into small drops in the diameter of 10—30 μm,and high recovery efficiency of crude oil from oil-sand was also obtained. Cosurfactants of BS were explored and 1-octanol was determined to be one of the optimal ones. The 1-octanol/BS complex reduced the interfacial tension of crude oil/mineralized water to 10-3mN/m together with 3.2-fold-enhanced oil recovery efficiency.Equivalent oil washing capability was also obtained by fermentation broth with as low as 0.9 g/L BS,revealing that potential application of BS in enhanced oil recovery is promising.