Synthesis and demulsification performance of a novel low-temperature demulsifier based on trimethyl citrate

A significant amount of water-in-oil (W/O) emulsion is generated during petroleum extraction. However, the current commercial demulsifiers are expensive to produce and requires high demulsification temperatures, leading to increased energy and economic consumption. To enhance the efficiency of demulsifiers and reduce the cost of demulsifying W/O emulsions, we have successfully developed a novel demulsifier named TCED through a straightforward two-step process. This demulsifier features trimethyl citrate as the hydrophilic core grafted with three hydrophobic chains. Its structure was characterized using EA, FT-IR and ¹H NMR spectroscopy, and the demulsification performance was comprehensively evaluated. At a low demulsification temperature of 40 °C, TCED demonstrated a remarkable demulsification efficiency (DE) of 99.06% and 98.74% in emulsions containing water contents of 70% (E70) and 50% (E50), respectively. Especially, a DE of 100% could be obtained in both E70 and E50 emulsions at a concentration of 600 mg/L. Moreover, TCED displayed a high DE even at high salinity levels of 50,000 mg/L and across a wide pH range of 2-10. Additionally, the phase interface was consistently clear after demulsification. To investigate the demulsification mechanism of TCED, various adsorption kinetics experiments were conducted, including measurements of interfacial tension (IFT), surface tension (SFT), interfacial competitive adsorption, and stability of interfacial film. The results obtained from the experiments indicated that TCED possessed remarkable diffusion and replacement capabilities within the emulsions. As a result, it effectively disrupted the original interfacial active substances, such as asphaltenes aggregates found in crude oil. TCED exhibits a high DE at low concentration and temperature. This characteristic highlights its significant potential for low-temperature demulsification applications in the petroleum industry.