Stability and photo demulsification of oil-in-seawater Pickering emulsion based on Fe3+ induced amphiphilic alginate

The oil/water separation of oil-in-seawater emulsion plays an important role in resource recovery and ecological environment restoration. In this work, oil-in-seawater Pickering emulsion in seawater with high salinity was stabilized by Fe3+ ions and amphiphilic alginate (AM-Alg), subsequently destabilized by UV light for efficient oil/water separation. Initially, AM-Alg exhibited high viscoelasticity at the oil-water interface, which was confirmed by Quartz crystal microbalance. The addition of Fe3+ caused the aggregation of AM-Alg at the oil-water interface and improved the formation of the three-dimensional interpenetrating network structure. When Fe3+ was at 0.1 mol/dm3, the oil-in-seawater Pickering emulsion had the best stability, and also the fastest demulsification speed under UV light. Moreover, the photochemical redox reaction rate and the conversion rate of Fe3+ were the highest. This photo demulsification technology is expected to become a new method of dealing with marine oil spills.