Magnetohydrodynamic electrochemistry in the field of Nd-Fe-B magnets. Theory, experiment, and application in self-powered flow delivery systems

Nd-Fe-B permanent magnets are easily available, powerful, and inexpensive a nd generate strong quantifiable convective effects during electrolysis, sim ilar to those obtained with rotating electrodes or large electromagnets. Th e magnetic field of Nd-Fe-B magnets has been simulated numerically and mapp ed. Its most characteristic difference from the field of most commercial el ectromagnets is the presence of magnetic field gradients, which introduce a dditional body forces in the electrolytic solution and create new modes of mass transfer due to the attraction of electrogenerated radicals into areas of stronger field. The effect of those new forces on the radial distributi on of the flow profile in the vicinity of the electrode has been monitored with generation-collection experiments and optical photography. The emergin g utility of Nd-Fe-B magnets in systems of chemical interest is demonstrate d with flow control and delivery devices, based on galvanic cells configure d as self-powered magnetohydrodynamic pumps.