The Effect of Temperature on the Acidic Dissolution of Steel in the Presence of Inhibitors

Abstract

The corrosion of mild steel in sulfuric acid containing 4 × 10−4 M of either D-galactose thiosemicarbazone, 1 -phenyl thiosemicarbazide, or 4-phenyl thiosemicarbazide, has been studied over the temperature range 25 to 60°C by using alternating current (AC) impedance spectroscopy technique and measuring the capacitance of the double layer. Results reported in this paper elucidate the effect of temperature and the molecular structure on the inhibition efficiency. The anodic dissolution process was found to be under activation control for all the compounds investigated at different temperatures. Moreover, the inhibitors investigated in this paper do not affect the mechanism of the dissolution process. Thermodynamic parameters for adsorption of the compounds are calculated using the Temkin adsorption isotherm.