Chemical Engineering Journal, Vol.309, 513-521, 2017
Effective removal of emulsified oil from oily wastewater using in-situ generated metallic hydroxides from leaching solution of white mud
Leaching solution of white mud (LSWM), a form of industrial waste from alumina plants, was added to alkaline oily wastewater, and metallic hydroxides were in-situ generated (IGMHs). We evaluated the removal efficiency of emulsified oil by IGMHs from simulated alkali/surfactant/ polymer flooding produced water. The influence of various factors, such as LSWM dosage, initial pH, temperature, and contact time on oil removal efficiency was investigated. It was found that approximately 95-99% of emulsified oil was successfully removed by the co-precipitation/adsorption process. In addition, highly basic conditions and lower temperatures were preferred for IGMHs to remove emulsified oil. Thermodynamic analysis showed that the co-precipitation/adsorption process was spontaneous, exothermic and physical in nature, involving weak interactions, such as electrostatic attraction, hydrogen bonding, and adhesive force between the emulsified oil droplets and the binding sites on the surface of IGMHs. It was observed that IGMHs lost approximately 18.9% adsorption capacity for emulsified oil after more than four cycles. Therefore, IGMHs could be used effectively for at least four cycles. Moreover, recovery of oil from oily wastewater could improve the economic viability of this treatment process. (C) 2016 Elsevier B.V. All rights reserved.