Effects of crosslinking in demulsifiers on their performance

Chemical demulsification is the most widely used method for breaking water-in-diluted bitumen emulsions in oil sands processing. In this work, the properties and performance of six ethylene oxide (EO)-propylene oxide (PO) demulsifiers from three families were investigated. The demulsifiers were characterised by their relative solubility number (RSN) and number of EO-PO branches. The results showed that the performance of the demulsifiers is correlated to the starting base compound, number of EO-PO branches, RSN, oil/water interfacial tension (IFT), increase of molecular weight (MW) by incorporation of crosslinks in EO-PO branches and yield stress of underflow. An increase in MW by the incorporation of crosslinks in EO-PO block copolymers decreased the RSN value while improved the dehydration efficiency. Dynamic IFT measurements revealed that the higher adsorption of EO-PO block copolymers at the oil/water interface on crosslinking, which resulted in higher dehydration efficiencies. The yield stress of the underflow increased on crosslinking the EO-PO block copolymers due to the release of more water and solids to the underflow, which increased the number of aggregates present in the underflow, resulting in increased immobility and constriction and higher yield stress.