Synthesis and performance of a tetra-branched bicationic liquid demulsifier

The treatment of water-in-oil (W/O) emulsions has always been a challenge in the petroleum industry. In this article, a tetra-branched bicationic liquid demulsifier (PAL-Cl) was prepared. The structure of PAL-Cl was confirmed by Fourier-transform infrared spectrum (FT-IR), Nuclear magnetic resonance spectrum (NMR) and Gel permeation chromatography (GPC). Some factors affecting demulsification efficiency (DE) such as dosage, salinity, pH, temperature, etc. were explored in detail. The DE reached 96.5 % after demulsifying with 50 mg/L of PAL-Cl at 70 °C for 240 min. Especially, a relatively lower temperature of 40 °C could obtain the DE of 94.1 % with 250 mg/L of PAL-Cl for 360 min. Moreover, PAL-Cl has outstanding acid, alkali and salt resistance. In addition, the demulsification mechanism was in detail investigated by surface tension (SFT), interfacial tension (IFT), competitive adsorption experiments, coalescence time of droplets (CT), three-phase contact angle (CA), zeta potential and micrographs.