Preparation of Oil-in-Seawater Emulsions Based on Environmentally Benign Nanoparticles and Biosurfactant for Oil Spill Remediation

One remediation technique of oil spills is the application of dispersants to oil slicks, which is essentially a process of emulsification. Tetradecane and crude oil-in-seawater emulsions formed with silica nanoparticles modified in situ with rhamnolipid produced a longer stability and smaller droplet size. The interactions of silica particles with rhamnolipid were characterized by contact angle, interfacial tension, TEM, and SEM measurements. The images of confocal fluorescence microscopy and SEM showed the oil droplet microstructure and the morphology of nanoparticles at the oil droplet–water interface. The average emulsion droplet size and emulsion index were investigated. These results indicated a synergistic stabilization upon rhamnolipid addition. The synergy was even more efficient in the case of seawater with a high salinity. Here, because of the strong flocculation caused by high salinity, silica nanoparticles alone were not an effective emulsifier in seawater. The modification of silica nanoparti...