ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

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

Rasha J. Jadaa, Ahmed N. Abd, and Anees A. Khadom

Department of Chemistry, College of Science, University of Diyala, Baquba City, Iraq

E-mail: aneesdr@gmail.com

Received: 12 April 2021  Accepted: 31 May 2021

Abstract:

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 °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.

Keywords: Corrosion; Polymeric inhibitor; Mild steel; Acidic solution; FTIR; UV–Vis

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-021-01725-5

Chemical Papers 75 (10) 5375–5386 (2021)