*11.5.3.2 Inorganic inhibitors*

The compounds such as As2O3, Sb2O3 have been reported as inhibitors in acid media. In this case, the protection is due to the reduction of electro positive ions and deposition on the metal surface and lowering of the over voltage of main cathodic depolarization reaction [38]. Recently it is shown that the addition of heavy metal ions such as Pb2+, Ti+ , Mn2+ and Cd2+ is found to inhibit corrosion of iron in acids.
