Corrosion Inhibition of Some Alloys in Acidic Media Using Inorganic (K\(_2\)CrO\(_4\)) and Organic (C\(_6\)H\(_5\).NH\(_2\)) Inhibitors

Abstract

Corrosion of metal is an electrochemical process that promotes the deterioration of metals. This phenomenon can be controlled or mitigated through the use of chemical inhibitors. Research in the use of chemical inhibitors is gaining wider interest. This study describes the use of inorganic (potassium chromate, K2CrO4) and organic (aniline, C6H5.NH2) inhibitors, as corrosion control for cold steel and aluminium alloys in acidic media using varying inhibitor concentrations. Experiments using weight loss (WL) techniques were adopted to evaluatethe extent of corrosion of the metals. The WL data were recorded for 1-7 days immersion period, and their efficiencies calculated in percentages, I.EM (%). For an optimum inhibition, the inhibitors were added above a certain minimum concentration. Corrosion rate (CR) was found to be higher (0.07) in 11 g/L than in 2 g/L concentration (0.02) in K2CrO4 for the aluminium metal. Similarly, in the presence of the potassium chromate inhibitor, the corrosion rate in cold steel varied slightly (0.04; 0.06) in the 11 g/L and 2 g/L concentrations respectively. The I.EM (%) was found to increase from the 2.0 g/L to 11.0 g/L immersed in HCl and HNO3at 0.5 M respectively. Corrosion inhibitions were found to increase with increase in concentrations of inhibitors. The results obtained indicated better inhibitor efficiency in the higher concentration than in the lower concentration in the presence of the inorganic and organic inhibitors in cold steel and aluminium metals respectively. The highest I.EM (%), (92.41%) was recorded for potassium chromate at 11 g/L, whereas, the least I.EM (%) was recorded for potassium chromate (37.90%) at 2 g/L. The results showed that the application of higher concentrations of both inorganic and organic inhibitors in the metal-inhibitor-media interaction yielded greater protection and significantly mitigated the corrosion reactions for cold steel and Aluminium in both acidic media. These results may find wider applicability in the formulation of appropriate anti-corrosion system by scientists, policy-makers and environmental stakeholders on critical assets especially in the petroleum and allied chemical industries.