Constructing oxygen-based multiple hydrogen bonding sites and delocalized π bonds for efficient oil-water-solid interfacial separation.

Separation of oil-water emulsions co-stabilized by solid particles and natural interfacially-active components has always been a challenge in petroleum and coal industry. Herein, we constructed and synthesized an interfacially-active nonionic material by esterification and polymerization, which contains multiple oxygen-containing groups (-COOH, -C-O, -COOR) and aromatic rings. The lab bottle tests show that this polymer (1000 mg/L) could completely break the silica-asphaltene co-stabilized water-in-heavy oil emulsions at 60 °C within 45 min, much faster and higher than those of commercial and reported demulsifers (>75 °C, >90 min). Mechanistic study by interfacial characterization and molecular dynamics simulation shows that this newly synthesized polymer possesses multiple hydrogen bonding sites and delocalized π bonds. These functional groups and active sites play the vital role in reconstructing and breaking the interfacial film by non-covalent interactions reconstruction, repelling the coated heavy fractions (e.g., asphaltenes) from the fine solids surface. The introduction of aromatic rings with delocalized π bonds into the polymer provides it with a solubilizing effect on asphaltene and promotes the dispersion of asphaltene aggregation, enhancing the demulsification efficiency. In addition, these hydrogen bonding sites can also build connecting bridges between emulsified droplets, facilitating the coalescence of them. This work would provide insights for developing efficient functional materials for low-carbon separation of complex emulsions in industry, including oily sludges, water-in-oil emulsions.