Magnetomobility of Paramagnetic Ions and Solution Droplets

Separation of rare earth ions with strong magnetic fields Rare earths elements (REEs) are a group of 17 elements in the periodic table, including the 15 lanthanides, scandium and yttrium. These elements are today critical because of their essential role in applications such as permanent magnets, lamp phosphors, catalysts, rechargeable batteries, etc. They occur in nature as mixtures and are very difficult to separate into the individual elements due to almost identical chemical properties. Traditional separation methods, based of chemical properties, demand fastidious steps and are not environmental friendly. Our objective is to explore magnetic properties of individual rare earth ions ions (paramagnetic - attracted to a magnetic field; and diamagnetic - repelled by a magnetic field) to develop an unconventional process of separation. During the 50's, Noddack et al. obtained a partial separation of rare earth ions, however there is not much more literature on the separation of these elements. For the instance, we obtained interesting results showing the magneto-migration of paramagnetic ions (ex.: dysprosium) towards the surface of a magnet (NdFeB) and the diamagnetic ions (ex.: yttrium) moving in the opposite direction of the magnet surface. A more complex scenario seems to take place when mixtures of paramagnetic and diamagnetic ions are exposed to a magnetic field gradient. Opposite to the expected, both ions migrate together in the direction of the magnetic field. It can be can be assumed as a strong indication that rare earth ions do not behave as individual ions when in solution and submitted to a magnetic field. Instead, a cooperative effect seems to exist and research is still need to understand this behavior. Even the fact rare-earth ions in solution are influenced by a magnetic field is already a counter intuitive observation. Theory predicts that rare-earth ions are too small to be influenced by external magnetic fields and results with these observations are very challenging to explain and demand deeper explanations.status: publishe