High-viscosity Pickering emulsion stabilized by amphiphilic alginate/SiO₂ via multiscale methodology for crude oil-spill remediation

The separation of crude oil from oily water and collection of the emulsion constituents has attracted significant attention. We demonstrate that the relationships between inherent dynamic factors and the performance of a Pickering emulsion stabilized by SiO₂ particles with adsorbed hydrophobically modified sodium alginate derivatives (HMSA), a natural pH-sensitive polysaccharide, can be clarified via a multi-scale methodology. Functionalization of the silica surface with HMSA controls particle dispersibility, as verified by turbidity and stability analyses, the zeta potential, and transmission electron microscopy measurements. The interaction mechanism between HMSA and SiO₂ nanoparticles was elucidated by both experimental adsorption measurements and computer simulations, which showed qualitative consistency. The aggregation/disaggregation of HMSA/SiO₂ particles achieved by tuning the pH of the solution facilitated reversible dispersibility/collectability behavior. Overall, a high-viscosity Pickering emulsion system based on particle-particle and droplet-droplet interactions, which can be filtered for the recovery of spilled crude oil, was demonstrated.