Electrochemical hydrodynamics in a magnetic field with laser interferometry

Abstract

An unusual magnetic field effect on the concentration profiles during electrochemical deposition of copper in an unstirred electrolyte solution has been observed during a galvanostatic electrolysis which was followed using laser interferometry. The study was done on the Cu/0.1 N CuSO 4/Cu system at its natural pH and at different c.d.'s with plane parallel electrodes in the vertical position (V) and in the horizontal position of cathode over anode (C/A) and anode over cathode (A/C). The field produces a marked distortion of the interference fringes which indicate concentration gradients. The gradients are proportionately higher at higher c.d's in the range of c.d's of 0.12 mA cm −2 to 12.0 mA cm −2 with vertical (V-position) electrodes. In the C/A position the occurrence of a smooth increase in fringe bend with time suggests no hydrodynamic flow. Flow velocities observed using suspended particles range from 2 cm s −1 to 13 cms −1 at a magnetic field strength of 0.10–0.60 T. The shape of the interference fringes in an interferogram varies with electrode separation distance in the vertical position. The paramagnetism of the cupric ion which results in a magnetic fluid is also used in the explanation of the effects.