Anodic dissolution of mild steel in HCl solutions containing thio-ureas

The effect of thio-urea and its derivatives on the anodic dissolution of mild steel in HCl solutions has been studied. Thio-urea and N-substituted derivatives show maximum anodic polarisation at low concentrations. The anodic Tafel slope shows an abrupt change in the intermediate concentration range, i.e. 4-40 mM. This has been explained in terms of protonated species taking part in metal dissolution. S-substituted derivatives exert increasing anodic polarisation with increasing concentration. © 1983.