Chemical treatment of oilfield wastewater and the effect of temperature on treatment efficiency: A review

Treatment of the oilfield wastewater from the chemical and petroleum industries, often present in the form of emulsion, is one of the major environmental concern in current times. Demulsification is presently the most viable method to separate the oil and water from a rigid, homogenous emulsion especially, chemical demulsification. Mostly, chemical demulsifiers used at high temperature can give enhanced separation efficiency and result in the use of less dosage of expensive chemicals. Mainly, the reservoir conditions also exist at high temperature, thus, it is important to consider the effect of temperature for the selection of best choice among available demulsifiers. The review discusses the recent discoveries and modification among the existing demulsifiers such as triblock EO-PO copolymer, non-biodegradable polymers, branched copolymers and others. The major chemical demulsifiers and their upcoming alternatives such as the nanomaterial demulsifiers and ionic liquids have also been discussed in great details. Chemical structure and molecular weight were found to influence the emulsion breaking ability of a demulsifier. The surface properties play an important role in the selection of appropriate demulsifier whether hydrophobic or hydrophilic. Method of heating whether microwave or conventional heating, doesn't play a significant role in influencing the emulsion breaking efficiency of polymeric surfactants. However, microwave heating is preferred for demulsification by ionic liquids. Lastly, the whole mechanism of chemical demulsification and few upcoming chemical treatments for demulsification are also well described in brief.