Effect of magnetic fields on convection in solutions containing paramagnetic ions

Abstract

The objective of this study is to develop a mathematical model for the effect of magnetic fields on the corrosion process at an iron electrode in a solution containing paramagnetic and diamagnetic cations, Co 2+ and Fe 2+, respectively, and diamagnetic anions SO 4 2−, and to verify the mathematical model experimentally. The hypothesis is that, in the presence of a magnetic field in solution, where a gradient of concentration of paramagnetic ions exists due to some electrode reaction in which they participate, an additional driving force acting on the solution will arise. This force, which has the same direction as the gradient of the paramagnetic ions, will cause a redistribution of velocities in the diffusion layer. As a result an additional convective transport of all the components of the solution will be generated. Correspondingly, limiting currents of reactions proceeding in an electrochemical system will become a function of the applied magnetic flux density. Experimentally, the study is carried out by potentiostatic and open-circuit potential methods, and the results obtained show an anodic polarization due to the magnetic field. Both the mathematical model developed and the results obtained experimentally, show that the magnetic field effect increased with increasing magnetic flux density and electrolyte concentration, and decreased with increasing stirring rate. The results show no effect due to the rate of change of the applied magnetic field, which indicates that the effect obtained cannot, apparently, be explained in terms of the Lorentz force.