RIASSUNTO
Abstract
Permanent environmental damage cannot be compensated in terms of money. Unfortunately, oil spills contaminate water, restraining marine species of their habitat and food supply. Despite the numerous methods available today to clean up the water body affected by an oil spill by separation of oil and water, none have restored water to its previous quality or saved marine animals from its deleterious effects to the full extent. The biggest hurdle to this cause is the sunken oil; the oil which may have either sunken mixed with sand and mud or by dispersion due to weathering.
Ferro fluids are Fe3O4 based Magnetic Nano Particles (MNPs) which can be coated with a layer of polymer or surfactant to form a super-hydrophobic material which selectively adsorbs oil. This work involves coating the MNPs with Polyvinyl-pyrrolidone Styrene and Sodium Oleate. These colloidal ferromagnetic Nano-particles display considerably higher magnetic susceptibility. The MNPs are non-toxic nano sized sponges that sink deep inside the water body, adsorb 10 times their weight of oil and float back to the surface. It must be well-known that electrostatic attraction between negatively charged oil-in-water emulsions and positively charged MNPs controls the attachment of MNPs to the droplet surface; and the subsequent aggregation of the electrically neutral MNPs-attached oil droplets shows a critical role for accelerated and capable magnetic separation.
During the experimental work performed, it was seen that after separating out the recovered oil, the MNPs can be regenerated and re-used. In this work, a 1-D mathematical model was developed for describing the dynamics of the action of the MNPs for oil spill cleanup and its collection in the framework of the sedimentation theory. The model was based on Newton's law of Motion, theory of batch sedimentation, Settling velocity and Stokes-Einstein equation. In order to completely understand the process and to formulate a model that correctly and aptly mimics the experimental observations, the conservation equation for MNPs was also coupled with the flux function, which accounted for gravity force, magnetic force and Brownian interaction. Parameters like offshore constraints and weather conditions were considered while running the model, to make the model more robust, as well as to observe the impact on final obtained results.