Synthesis of a low temperature ionic liquid demulsifier and its demulsification mechanism

•Dual-center ionic liquid demulsifier (DEBIL) with hydrophilic center and hydrophobic chain structure was synthesized.•DEBIL has fast demulsification rate and high demulsification efficiency at low temperature, high salinity, and wide pH range.•DEBIL has better interfacial activity and can effectively replace asphaltenes at oil–water interface.•The preparation process of DEBIL is simple and safe compared with polyether demulsifiers.