Amphiphilic Ionic Polyethylene Wax with Exceptional Interfacial Activity for Demulsification of Water-in-Crude-Oil Emulsions

Abstract

As energy consumption globally keeps increasing, refining better and more efficient enhanced oil recovery (EOR) methods, especially those with surfactants, will be crucial to sustain future energy demand. Such advances will not just increase the economic viability of oil production but also contribute to long-term energy resource sustainability. Emulsifiers play a vital role in the oil industry by destabilizing water-in-oil emulsions, improving the quality of oil and reducing processing costs. In this study, polyethylene wax was first modified with maleic anhydride to obtain PE@MA. Then, in order to increase the hydrophilicity of the PE, a ring-opening reaction was performed on the maleic anhydride rings to prepare PE@MA^–Na⁺. Then, demulsification efficiency of the prepared compounds in W/O emulsions was studied. Pure maleic anhydride did not possess demulsifying properties and was not effective in water dehydration from oil. Polyethylene modified with maleic anhydride (PE@MA) showed a lower dehydration efficiency compared to the polyethylene wax modified with maleic anhydride salt (PE@MA^–Na⁺). The optimized salt-modified demulsifier, PE@MA^–Na⁺, possessed good interfacial properties to break the asphalt films at the oil-water interface with improved water dehydration. PE@MA^–Na⁺ displayed a dehydration of ≈100% at an exceptionally low dosage of 100 ppm in less than 5 min at a relatively low temperature (≤50 °C). The exceptional performance of the PE@MA^–Na⁺ can be attributed to its high amphiphilic interfacial properties, which facilitates interfacial adsorption, disrupts asphaltene-stabilized layers, and significantly reduces the interfacial tension. In summary, the above findings demonstrate that the PE@MA^–Na⁺ can be an efficient and promising next-generation demulsifier for the crude-oil dehydration.