Synthesis and demulsification performance of a Gemini ionic liquid with dual cationic active centers

Currently, widely-used demulsifiers are primarily produced using ethylene oxide and propylene oxide as raw ingredients. The production process is hazardous and complicated, and the demulsification temperature for crude oil emulsions is typically above 60 ℃. In this work, an efficient Gemini ionic liquid demulsifier (Y12) with dual cationic active centers was prepared using a one-pot synthesis route. The structure of demulsifiers was analyzed by FTIR and 1H NMR spectroscopy. The bottle test was utilized to assess the demulsification performance. The results revealed that the demulsification efficiency (DE) of Y12 could achieve 100 % at a concentration of 400 mg/L under 50 ℃ for 120 min. Emulsion with different oil content were treated with Y12 at different temperatures, the DE of C30 and C70 emulsions reached 100% at temperature of 50 ℃ and 70 ℃, respectively. Furthermore, Y12 exhibited effectiveness across a wide range of pH value and high salinity conditions. To further confirm the demulsification of Y12, some commercial demulsifiers were used for comparison. It was observed that Y12 had better performance than commercial demulsifiers, indicating its promising potential for applications. The demulsification mechanism was investigated through relative solubility numbers (RSN), interfacial tension (IFT), three-phase contact angle (TCA), zeta potential, and coalescence time of water droplets (CTW). Especially, to further investigate the demulsification mechanism of Y12 demulsifier, Y8 and Y16 with different lengths of hydrophobic chains were also prepared and used for comparison. Y12 had an excellent interfacial activity and strong capability of reducing interfacial tension, which facilitates the formation of an unstable composition interfacial film and results in the oil–water separation.