Bifunctional zwitterionic acrylic copolymer for efficient demulsification and demineralization of bitumen froth

Stable water-in-oil emulsions in naphthenic bitumen froth, formed during oil sands extraction, hinder downstream processing and require effective demulsification and demineralization strategies. This work presents the design and synthesis of a low molecular weight zwitterionic acrylic-based random copolymer for use as a bifunctional chemical, hereafter referred to as demulsifier/demineralizer, for the treatment of naphthenic froth generated from water-based extraction of Canadian oil sands. The monomer conversion showed strong dependence on the hydrophobic/hydrophilic monomer ratio, initiator amount, and initial monomer concentration. Water and solid removal efficiencies were influenced by the hydrophilicity, molecular weight, and dosage of the copolymer. Among the synthesized materials, the zwitterionic copolymer BA5545 b + AA, functionalized via an aza-Michael addition, exhibited superior performance at dosages as low as 100 to 125 ppm, despite its higher molecular mass. Contact angle measurements, AFM imaging, Langmuir-Blodgett trough experiments, and interfacial shear rheology suggest that enhanced wettability modification and more effective asphaltene displacement are associated with the acrylic acid grafts introduced via functionalization. These zwitterionic moieties may facilitate stronger hydrogen bonding, both between copolymer molecules and with water, enabling interfacial bridging. Such interfacial rearrangements are consistent with a weakening of the stabilizing film compared to the non-functionalized polymer. This work contributes to the understanding of structure-performance relationships in polymeric demulsifiers and provides insights that may aid the development of multifunctional chemicals for efficient bitumen froth treatment and oil/water/solid separation. • High efficiency in dewatering naphthenic bitumen froth • Effective disruption and destabilization of rigid interfacial films • Enhanced wettability modification for improved solid removal • Strong interfacial activity driven by hydrogen-bonding interactions