STUDIES ON THE INHIBITION OF ALUMINUM AND COPPER DISSOLUTION BY SOME UREA AND THIOUREA DERIVATIVES

Three derivatives of urea and thiourea have been prepared and treated as inhibitors for the corrosion of aluminium in 1 mol L-1 HCl and of copper in 3 mol L-1 HNO3. The inhibitor efficiencies are calculated from thermometric and weight loss techniques. These techniques indicate that the inhibition is principally governed by the adsorption of these compounds on the surface of aluminium and copper metals and the adsorbability of inhibitors is dependent on the basicity of the oxygen and sulphur sites involved. The inhibition efficiency increases in the order: 1-alpha-pyridylamino-3 benzoyl-2 thiourea > 1-alpha-pyridyl-amino-3 phenyl-2 thiourea > 1-alpha-pyridylamino-3 phenyl-2 urea.