Inhibition of mild steel corrosion in formic acid solution

The corrosion inhibition efficiencies of 2-benzylmercapto 1,4-diphenyl-1,6-dihydro, 1,3,5-triazine-6-thione and its chloro, nitro, methyl and methoxy derivatives have been evaluated at 298, 308 and 318 K. The percentage inhibition efficiencies have been found to increase with increase in the concentration of the inhibitor and the experimental temperature. There exists a good agreement between percentage inhibition efficiency calculated by the weight-loss and the electrochemical techniques. The inhibitive performance of so individual inhibitor has been discussed in terms of its adsorption on the surface of the corroding metal. All the inhibitors have been found to be potential inhibitors even at very low concentrations. The polarisation measurements indicate that these inhibitors enhance both anodic and the cathodic polarisation.