Polyacrylamide as a corrosion inhibitor for mild steel in 2 M phosphoric acid: experimental and theoretical studies

The corrosion inhibition behavior of mild steel in 2 M H3PO4 was investigated in the absence and the presence of Polyacrylamide (PAM) as a corrosion inhibitor. The influence of temperature and inhibitor concentration was studied using weight loss and electrochemical techniques. The results showed that PAM acted as a powerful inhibitor. The inhibition efficiency increased with PAM concentration and decreased with temperature. Maximum inhibition efficiency was 91.02% at 600 ppm of PAM and 30 degrees C. The adsorption of PAM on mild steel surface was found to fellow Langmuir adsorption isotherm. The value of the adsorption free energy was negative and lower than -20 kJ/mol, indicating a spontaneous and physical adsorption process. UV-Vis and FTIR investigations showed the formation of protective layer on mild steel surface. Statistical analysis is used to correlate the corrosion rate as a function of PAM concentration and temperature. Quantum chemical studies are used as a powerful tool for microscale analysis.

Automated summary

The study found that PAM is an effective corrosion inhibitor for mild steel, with its inhibition efficiency increasing with PAM concentration and decreasing with temperature. The adsorption of PAM on the mild steel surface follows the Langmuir adsorption isotherm.