Coalescence and separation of surfactant-stabilized water-in-oil emulsion via membrane coalescer functionalized by demulsifier

The coalescence and separation of surfactant stabilized water-in-oil emulsion was an important process in the chemical industry but the conventional thermo-chemical demulsification had high energy and reagent consumption. The studies on demulsification at room temperature via porous materials usually involved the emulsion with low water content (<1%). This study demonstrated the coalescence of W/O emulsion with 50% water content via filtration by a demulsifier-grafted polyether sulfone (PES) microfiltration membrane. The material worked as coalescer and it divided the emulsion into layered oil and water with high purity after filtration. The obtained material was analyzed by attenuated total reflectance infrared spectroscopy (ATR-FTIR) and X ray photoelectron spectroscopy (XPS) to prove the existence of demulsifier. When the demulsifier loading was 0.8 wt% of the solvent, the initiator loading was 0.8 wt% of the demulsifier, and the polymerization grafting was carried out at 50 °C for 5 h, the demulsification efficiency could reach 97.9%. The separation efficiency of the oil from water and the water from oil could get up to 99.5% simultaneously.