Oxygen-rich three-branched aromatic core demulsifier: Synthesis, demulsification for W/O emulsions and mechanism investigation

Traditional alkylphenol formaldehyde polyether demulsifiers feature complex synthesis, petroleum-dependent feedstocks and poor tolerance to high salinity/alkaline conditions. To address this gap, we synthesized a novel oxygen-rich three-branched aromatic demulsifier (TPS) with π-conjugated structures and dense hydrogen-bonding sites. Its tri-branched amphiphilic skeleton enables strong competitive adsorption against interfacial asphaltenes to reconstruct rigid oil-water interface (OWI) films. Bottle tests demonstrated that TPS achieved a demulsification efficiency (DE) of 94.15% for water-in-oil (W/O) emulsions at 300 mg/L and 45°C, outperforming two commercial demulsifiers. The performance remained stable over a wide salinity range of 0– 50,000 mg/L. In addition, a marked improvement in DE was observed under alkaline conditions, reaching as high as 99.04% at pH 12. Competitive interaction between TPS and ASP was systematically investigated using interfacial tension (IFT), three-phase contact angle (WCA), coalescence time (CT) and viscoelastic modulus (Vm). Based on density functional theory (DFT), molecular electrostatic potential (ESP) analysis identified potential hydrogen-bonding sites in TPS. Hydrogen bond (HB) energies were quantified using bond critical points (BCPs) derived from atoms-in-molecules (AIM) theory. Finally, a demulsification mechanism is proposed: TPS facilitates ASP desorption via synergistic non-covalent interactions between localized π-bonds and oxygen-containing groups, driving interfacial structural reconstruction.