Demulsification of stable seawater/Arabian heavy crude oil emulsions using star-like tricationic pyridinium ionic liquids

Abstract

Green oil-field chemicals based on ionic liquids (ILs) are highly recommended as demulsifiers for heavy crude oil emulsions due to their low vapor pressure, high thermal and chemical stability against degradation in harsh processing conditions. Novel multifunctional tricationic pyridinium ionic liquids (TCPyILs) were synthesized by the reaction of cyanuric chloride with tetraethylene glycol followed by its linking with quaternized aminopyridinium bromide using Bis(chloroethyl) ether as a linker. The chemical structures, surface and interfacial activities and thermal stabilities of the prepared pyridinium ILs were investigated. The amphiphilicity, surface and interfacial activity of the prepared TCPyILs recommended their application as chemical additives in petroleum industry. To the best of our knowledge, it is the first time to apply TCPyILs as demulsifiers for W/O emulsions with high stability and low droplet size (around 2 μm). Comparing with traditional monocationic pyridinium ILs, the prepared TCPyILs had higher efficiencies to demulsify W/O emulsions with different Vol %. The effects of alkyl chain lengths, demulsifier doses and RSN values on the demulsification activities were studied. The results indicated that TCPyILs with nonyl and tetradecyl alkyl chains had better and higher demulsification efficiency comparing with those containing hexadecyl alkyl chains. The demulsification efficiencies of TNPy and TTPy ILs for W/O (50/50, 30/70 and 10/90 vol%) reached 100% even at low concentrations.