FERROCLEAN: Ferrofluidic Extensional Rheological Response for Ocean CLEANup
The Portuguese Continental shelf is under high oil spill pressure, due to fishing, harbouring and shipping activities, among others. These activities may result in oil spills/discharges in the Atlantic Ocean that must be remediated to avoid their recognised immediate and long-term detrimental impact on ecosystems’ health, with heavy economic consequences. Such impacts include the incorporation of oil carbon into planktonic food webs and a variety of life-threatening toxic effects (e.g. increases mortality, growth delay and decreased reproduction) resulting from the interaction of oil contaminants with molecular targets in aquatic organisms.
Technologies available for spills clean-up and mitigation are yet of limited recovery efficiency or have unaffordable energetic demands. Recently, MIT researchers proposed a magnetic clean¬up method consisting of mixing synthesised magnetic nanoparticles and dispersing them in oil-polluted water in a vessel to form a ferrofluid either in the oil-phase or in the water-phase. When the ferrofluid is formed with the oil-phase and the mixture is placed in an oil-recovery vessel containing an array of specifically arranged permanent magnets (Halbach array), the magnetic oil in the reservoir can be attracted to the top of the array, above water level, through the sides of the magnets, forming beaded spheres around the magnets’ ends. The magnetic field thus separates the oil from the water phase much faster than gravity (phase-separation method by sedimentation), and without use of electrical power. Later on, existing technology can recover the magnetic particles from the oil, for future separate reuse of both the oil and the nanoparticles. Though the design seems to work well, the efficiency of the Halbach array as oil-recovery system has yet to be determined. In particular, the rheological properties of ferrofluids influencing performance of the Halbach array are in need of deeper characterisation and modelling. FERRO-CLEAN is a multidisciplinary project gathering experts in material science, transport phenomena, and environmental toxicology that aims at developing knowledge to improve the efficiency of the magnetic cleaning-up process of oil spills. This will be achieved by: 1) providing an experimental tool for rheological characterisation of magnetic fluids simultaneously undergoing an extensional flow and a magnetic field, which intensity and orientation would be tunable; 2) performing a systematic and full rheological characterisation under shear and extensional flow of different ferrofluids, and 3) assessing the relationship between efficiency of the Halbach array in water clean-up, including the decrease in chemical load and toxicity potential, with the rheological properties of the ferrofluids.
- FCT, REPUBLICA PORTUGUESA