Analysis of the use of microemulsion systems to treat petroleum sludge from a water flotation unit

Abstract This work analyzes a treatment process for petroleum sludge from a flotation unit using microemulsion systems. Microemulsion systems employed were formulated using saponified coconut oil as surfactant, n-butanol as co-surfactant, kerosene as oil phase, and 2% NaCl solution as aqueous phase. The co-surfactant to surfactant ratio (C/S ratio) was kept constant at 4. A central composite rotational design (CCRD) was used for optimizing the process. The experiments investigated the influence of microemulsion to petroleum sludge ratio (MES/PSF, 0.5–7.5 g/g), temperature (T, 27–60 °C), and solubilization time (t, 30 to 150 min). The results show that the process is influenced largely by the microemulsion to petroleum sludge ratio (MES/PSF), with almost all solubilization efficiencies greater than 90%. The optimal conditions were obtained at: MES/PSF ratio = 4, T = 60 °C, and 1 h solubilization time.