Corrosion Studies of Mild Steel in Organic Acid/Chloride Media

Eugene Uwiringiyimana1, Oscar Gumiriza1, Odonnell P. Sylvester1, Feyisayo V. Adams1,* and Antoine F. Mulaba-Bafubiandi2

1Department of Petroleum Chemistry, School of Arts and Sciences, American University of Nigeria, Lamido Zubairu Way, Yola Township by-Pass, PMB, 2250 Yola, Nigeria

2Department of Metallurgy, Mineral Processing and Technology Research Centre, Faculty of Engineering and The Built Environment, University of Johannesburg, Doornfontein, Johannesburg, South Africa

Abstract

This study investigated the corrosion behaviour of mild steel immersed in 0.5 M organic acid media and in 90 %/10 % 0.5 M organic acid media/ 3.5 % NaCl by surface observation and weight loss technique. In all the solutions (0.5 M organic acid and the organic acid containing 3.5 % NaCl), mild steel corroded more in acetic acid compared to other solutions, while NaCl was lowest. The corrosion rate of mild steel immersed in 90 % organic acid contaminated with 10 % of 3.5 % NaCl was lower than that found when the steel samples were immersed in 100 % organic acid. It can be suggested that there was lack of Cl ions which could break down passive films on the mild steel surface to accelerate corrosion. Scanning electron microscope (SEM) was used to examine and characterize the mild steel surface before and after its immersion in the respective media. The elemental composition on the corroded surface of mild steel was detected with the SEM coupled with electron dispersive spectroscopy. The SEM and the physical observation results showed corrosion products, which were confirmed to be oxide films on the surface of the mild steel studied in 100 % organic acid solutions. Meanwhile, morphology of the mild steel after corrosion in organic acids containing NaCl showed that the corrosion products were protective oxide films. The oxides of Fe, Mn, Na, and Si were mostly detected on the surface of mild steel after corrosion.

Keywords

Chloride, Corrosion, Organic acid, Mild steel.

  
 
  • Asian J. Mat. Chem. /
  •  2017 /
  •  2(3-4) /
  •  pp 109-114
  • DOI:10.14233/ajmc.2017.AJMC-P48