Investigation of the kinetics of oil-suspended particulate matter aggregation

•OSA formation reaches equilibrium (24-47% of Emax) within 5 h after the spill.•The oil-to-sediment ratio reaches 0.24-0.68 within 5 h following the oil spill.•Solid and single-droplet OSAs are dominant under low mixing energy.•Increase of sediment concentration and mixing energy enhances OSA formation.•The OSA size increased with the shaking time.

The process of oil-suspended particulate matter aggregation (OSA) has been recognized by the oil spill remediation community to enhance the natural cleansing of oiled shorelines. A laboratory study was conducted to investigate the kinetics of OSA formation under various mixing intensities using the standard reference material 1941b and Arabian heavy crude oil. The results showed that formation of OSAs increased exponentially with mixing time and reached a maximum within 5 h. The maximum oil trapping efficiency increased from 24% to 47%, and the required shaking time decreased from 4.5 to 1.2 h as the sediment concentration and mixing energy increased. The maximum oil-to-sediment ratio reached 0.24-0.68 g oil/g sediment within 5 h. Most of the formed OSAs were solid OSAs and single droplet OSAs with low mixing energies, and multi-droplet OSAs with high mixing energies. The sizes of the dispersed oil droplets and OSAs were also investigated.