Corrosion inhibition potentials of some phosphovanadate-based glasses on mild steel in 1 M HCl

A new corrosion inhibitor, namely Phosphovanadate-Based Glasses of composition (0.25-0.5y)Bi2O3-yBaO(0.75-0.5y)(0.5P2O5-0.5V2O5) with (0 < y < 0.3) has been synthesized and its inhibiting action on the corrosion of mild steel in molar hydrochloric acid (1 M HCl) was investigated by using different electrochemical techniques: potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The experimental results revealed that Phosphovanadate glass is an efficient inhibitor and the inhibition efficiency E% increases with inhibitor concentration to reach a value of 98% at a concentration of 100 ppm for P2, which appears to be mixedtype inhibitors with predominant cathodic effectiveness. Indeed, the charge transfer resistance increases with concentration from 50 to 100 ppm and then decreases. The results recorded from the polarization tests were in good agreement with those obtained from the EIS studies. The effect of temperature (298-328 K) on the behavior of steel in 1 M HCl with or without these inhibitors shows that the increase in temperature leads to a decrease in the inhibition efficiency. The kinetic parameters (activation energy, activation enthalpy and activation entropy) were calculated and discussed. The thermodynamic study shows the formation of a film on the steel surface by physisorption in the presence of an inhibitor.

Automated summary

The Phosphovanadate-based glass is an efficient inhibitor with predominant cathodic effectiveness as a mixed-type inhibitor. The inhibition efficiency increases with concentration but decreases with temperature rise.