Adsorption and inhibition effect of 5-phenyl-1,2,4-triazole-3-thione on C38 steel corrosion in 1 M HCl

Based on potentiodynamic polarization measurements and electrochemical impedance spectroscopy, 5-phenyl-1,2,4-triazole-3-thione (PTT) was investigated as a corrosion inhibitor for C38 steel in 1 M HCl solution. The effects of temperature and immersion time were also studied. The corrosion inhibition efficiencies as measured by all the above techniques were in good agreement with each other. The results showed that PTT is a very good inhibitor for C38 steel in acidic media. It acts as a mixed inhibitor. The inhibition efficiency increases with increasing inhibitor concentration and decreases with increasing temperature and immersion time. Thermodynamic and activation parameters are discussed. Adsorption of PTT was found to follow the Langmuir adsorption isotherm. A physisorption mechanism is proposed.