Dissolution of Brass in Sulfuric Acid Solutions

The dissolution of 85/15 brass from rotating cylindrical samples by aerated dilute ulfuric cid solutions was investigated over the range of 15°–35°C. The reaction was found to proceed in three successive steps, dezincification of the brass surface, dissolution of redeposited copper and etching of the brass surface, and dissolution of the etched, dezincified surface. The dissolution rates of the last two steps were determined by the rate of dissolution of copper, zinc being dissolved as fast as it was uncovered by the dissolved copper. The mechanism of dissolution of copper from 85/15 brass was found to be similar to that of pure copper, controlled by the rate of oxidation of cuprous ions to cupric. Rate equations are given for the apparent dissolution rate of copper at each stage. Hydrogen peroxide was a reaction product.