Modified Hyperbranched Polyethylenimine as a Novel Demulsifier for Oil-in-Water Emulsions

The demulsification of oil-in-water emulsions with microdroplets has drawn great attention as a result of their extreme stability and difficulty of separation. In this work, a series of palmitoyl-hyperbranched polyethylenimine (CHPEI) with a hyperbranched structure was developed to meet the requirement of the demulsification. The influential factors of the demulsifier concentration, sedimentation time, and temperature on demulsification were investigated to give a clear view of CHPEI-based demulsification. The results indicated that the oil removal efficiency reached 91% by adding 80 mg/L CHPEI with sedimentation time of 30 min and showed a short sedimentation time and low addition amount compared to traditional demulsifiers. Further, to better acquire the mechanism of demulsification, the oil–water interfacial tension of CHPEI demulsifiers in aqueous phase and the real-time size changes of oil droplets were both recorded. These properties make CHPEI a potential candidate as an efficient demulsifier for crude oil.