Corrosion of Copper in Deaerated and Oxygenated 0.1M H2SO4 Solutions under Controlled Conditions of Mass Transfer


The corrosion behavior of copper in deaerated and oxygenated 0.1 H2SO4solutions has been investigated using the rotating cylinder electrode under turbulentflow conditions. Potentiostatic polarization measurements were carried out at differentbulk temperatures of 283, 288, 293 and 298 K and various speeds of rotation viz 100,200, 300 and 400 r.p.m. The anodic dissolution of copper and the hydrogen evolutionreaction, in deaerated and oxygenated solutions, are activation controlled processesdependent on the temperature of the solution. The anodic dissolution of copper is notmass transfer controlled. The results are consistent with a mechanism which suggeststhat oxidation of copper takes place in two steps of one electron each. The second step,i.e., cuprous ion (Cu+) oxidation, is the rate controlling. Moreover, the mechanism ofhydrogen evolution reaction is a proton discharge upon the metal surface. The chargetransfer of the oxygen reduction reaction is a 2e process in the range of bulktemperatures employed, i.e., the oxygen reduction is controlled by 2e process.Furthermore, the limiting current density value of the oxygen reduction reactionincreases as the velocity of the fluid increases. The results, at a constant bulktemperature are consistent with Eisenberg et al theory for mass transfer to a rotatingcylinder electrode surface