Abstract: Kerosene as oil phase, sodium dodecyl benzene sulfonate(SDBS) as the major surfactant, and pentanol as co-surfactant, three types of microemulsions, i.e. lower-phase(O/W), middle-phase(biconti-nuous) and upper-phase(W/O), were obtained upon the changing of NaCl concentration. The removal of crude oil from oily sludge by the microemulsions was studied, and the effects of microemulsion type, oily sludge concentration, time and temperature on crude oil removal efficiency were examined. The results show that the crude oil removal of the oil phase in lower-phase microemulsiom from the oily sludge is most efficient, followed by middle-phase microemulsion, and upper-phase is the lowest. Meanwhile, a good linear relationship between the crude oil removal efficiency of oil phase and oily sludge concentration is observed. When the detergency time varied between 10-60 min and temperature between 20-70℃, there is no remarkable change observed. Thus, the oily sludge can be treated fast by the studied microemulsion at room temperature.

Key words: Microemulsion, Oily sludge, Crude oil recovery