Imidazolium-based poly(ionic liquid)s for demulsification of water in crude oil emulsions

Imidazolium-based ionic liquids (ILs) and their corresponding poly(ionic liquid)s (PILs) as powerful demulsifiers for water separation from the crude oil emulsions were used. Vinyl imidazolium-based ILs were prepared and then polymerized according to the free radical homo-polymerization. NMR and FT-IR analyses confirmed the successful synthesis of ILs and their corresponding polymers. Demulsifying properties of different synthetic ILs, including [C12-VIM][Br], [C10-VIM][Br], [C8-VIM][Br], [C6-VIM][Br], [C4-VIM][Br], and [Benzyl-VIM][Br]) and their analogous poly(ionic liquid)s were evaluated and compared with each other. The influence of the important parameters on the emulsion breaking such as demulsifier concentration, the alkyl chain length of the synthesized demulsifiers, and the operating factors such as the stirring rate, stirring time, and temperature were investigated through the bottle test. Maximum dehydration efficiencies around 99.2% for [C12-VIM][Br] at 400 ppm and 100% for P[C12-VIM][Br] at 50 ppm were achieved after 4 hours at 70 degrees C, 15 minutes stirring time, and 800 rpm stirring rate. After demulsification of the crude oil emulsions, the interfacial tension decreased from 22.18 +/- 0.1 to 0.83 +/- 0.2 mN/m for [C12-VIM][Br] and from 20.18 +/- 0.2 to 0.70 +/- 0.2 mN/m for P[C12-VIM][Br]. The average diameter of the water droplets increased from 2-10 +/- 0.63 to 30-140 +/- 0.51 for [C12-VIM][Br] within 20 minutes. In addition, the residual water content decreased from 20% to 0.04% for [C12-VIM][Br] within 24 hours.