Influence of iodide ions on inhibitive performance of tetraphenyl-dithia-octaaza-cyclotetradeca-hexaene (PTAT) during pickling of mild steel in hot sulfuric acid

A macrocyclic compound, namely 2,3,9,10-tetraphenyl-6,13-dithia-1,4,5,7,8,1 1,12,14-octaaza-cyclotetradeca-1,3,6,8,10,13-hexaene (PTAT) was synthesized to study the corrosion inhibitive effect on pickling of mild steel in 20% H2SO4 at 95 degreesC. The synergistic effect of this compound was studied b y weight-loss, potentiodynamic polarization, electrochemical impedance spec troscopy and hydrogen permeation studies. The results of this investigation have shown enhancement in inhibition efficiency (IE) for 500 ppm PTAT in t he presence of 0.25% KI as a synergent. Formulated inhibitor has shown bett er performance than commercial corrosion inhibitor (Metasave). Potentiodyna mic polarization studies showed that PTAT is a predominantly cathodic inhib itor whereas Metasave is mixed in nature. (C) 2001 Elsevier Science B.V. Al l rights reserved.