Doping Si/O to enhance interfacial occupancy of demulsifiers for low-carbon breaking of water-in-heavy oil emulsions

Abstract

Separating water-in-heavy oil (W/HO) emulsions at low (room) temperature is challenging when exploiting heavy oil. We propose an adaptable strategy for constructing Si/O-doped demulsifiers. A nonionic demulsifier (APBMP) has been synthesized based on polysiloxane modified by allyl polyether and butyl acrylate. APBMP achieves 95.97% dehydration within 5 min for W/HO emulsions at 288.15 K and complete dehydration in 15 min at 323.15 K. Mechanistic studies found that doping Si/O into the demulsifier molecules increases the number of hydrogen bond sites, which enables the demulsifiers to quickly disperse natural stabilizers (e.g., asphaltenes) and replace them at the oil–water interfacial film. The demulsifiers prefer to occupy the interfacial sites rather than dissolve into the bulk oil or water phases. Driven by hydrogen-bond-dominated noncovalent interactions, the oil–water interfacial film is softened, reconstructed, and broken. These findings provide insights into developing novel materials for oil–water separations in a low-carbon way.