TRANSIENT ELECTROCHEMICAL METAL DISSOLUTION IN BINARY ELECTROLYTES

Several methods were used to calculate the electrolyte concentration changes in the solution layer next to the electrode during the high-rate anodic dissolution of metals under the transient conditions prevailing after application of a given current. It was established when comparing the results of the calculations and experiments that at the end of the transition period (when the anode potential rises steeply), a concentration of metal salt is attained at the electrode surface which exceeds that of a saturated solution. The degree of supersaturation cannot be determined exactly owing to a lack of data concerning the transport properties in supersaturated solutions; for a number of specific examples, estimates were given for the minimum degree of supersaturation. It was concluded that the most reliable data as to the concentration changes could be calculated, under the conditions investigated, by a numerical method which allows one to take into account the special features of ionic transport processes at high current densities and appreciable electrolyte concentration gradients in the diffusion layer at the electrode.