A gemini ionic liquid and its low-temperature demulsification performance in water-in-crude oil emulsions

In the demulsification process of crude oil emulsions, the temperatures of above 60 degrees C are most commonly required. In this work, a gemini ionic liquid (PGE-TFA) with amphipathy and interfacial activity was prepared by a simple and safe method, which could be used at the temperature of 40 degrees C for the effective demulsification of crude oil emulsions. The chemical structure and thermostability was investigated by FTIR, 1HNMR and TGA. The demulsification tests of PGE-TFA showed that it had higher demulsification efficiency (DE) and faster demul-sification rate than common commercial demulsifiers. PGE-TFA could be used at a low temperature of 40 degrees C, a wide pH range and high salinity. The DE reached as high as 95.53 % in water-in-oil emulsions with the con-centration of 500 mg/L at 40 degrees C for 90 min. The temperature of 70 degrees C could slightly increase the DE and significantly improve the demulsification rate, and the DE of 97.72 % was obtained with the same concentration for 30 min. In addition, the demulsification mechanism was investigated by dynamic interfacial tension, competitive adsorption and zeta potential. The results displayed that PGE-TFA had amphipathy and interfacial activity, which promoted it quickly diffuse to the oil-water interface and displace asphaltenes at the interface. Therefore, an unstable composite film could be formed at the interface and the interfacial tension was lowered, which induced the demulsification of the emulsions.

Automated summary

In this study, a gemini ionic liquid called PGE-TFA was prepared and found to have excellent demulsification properties for crude oil emulsions, even at a lower temperature of 40 degrees C. It exhibited higher efficiency and faster rate of demulsification compared to commercial demulsifiers, and could be used in a wide range of conditions.