Deep remediation of oil spill based on the dispersion and photocatalytic degradation of biosurfactant-modified TiO2

Abstract

The employment of dispersant was an effective method to treat marine oil spill pollution. However, conventional dispersants only showed a single oil dispersion. Here, by modifying TiO₂ nanoparticles with biosurfactant-Rhamnolipids (Rha), a highly efficient particulate dispersant with photocatalytic activity was developed. Rha-TiO₂ showed both excellent oil spill dispersion and facilitated photodegradation for oil simultaneously. The oil droplets dispersed by Rha-TiO₂ in seawater exhibited long time stability, which indicated the synergistic emulsification interactions between TiO₂ and Rha in artificial sea water (ASW). The dispersion mechanism of Rha-TiO₂ was analyzed, we found the TiO₂ nanoparticles alone weren't effectively emulsified oil in high salinity ASW, but the addition of a small amount of Rha could modify the surface wettability of TiO₂ nanoparticles to form the stable emulsion. In addition, the addition of a small amount of Rha could reduce the surface tension of the oil-water interface, which contribute to increasing the content of TiO₂ nanoparticles at the oil-water interface, form a steric rigid layer around the oil droplets to prevent droplet coalescence and facilitate the further photocatalytic degradation of oil. In short, the Rha-TiO₂ nanoparticles could effective disperse oil in ASW, meanwhile the TiO₂ also played the role of photocatalytic degradation of oil pollution. Hence, this study developed a novel photocatalytic particulate dispersant to remediate marine oil spill and delivered a new feasible solution for practical oil spill treatment in the future.

Keywords: Dispersion; Oil spill; Photodegradation; Pickering emulsion; Rhamnolipid; Titanium dioxide.