Corrosion of inhibitor treated mild steel immersed in distilled water and a simulated salt solution

Abstract

The purpose of this study was to investigate the performances of three inhibitors in controlling corrosion of local mild steel products in distilled water and a simulated salt solution. Corrosion inhibition of mild steel was investigated using electrochemical techniques. Untreated and inhibitor treated specimens were fully immersed in two test solutions, distilled water and the simulated solution of 2.0?wt.% NaCl and 1.0?wt.% Na2SO4. During full immersion in the simulated salt solution, sodium dihydrogen orthophosphate was not effective at all, resulting in even higher corrosion rates than that of the untreated specimens. Sodium benzoate was effective for three days only. Dicyclohexylamine nitrite was the most effective of them all, keeping its effectiveness for as much as 20 days. When the specimens were immersed in distilled water, all three inhibitors were effective during the 60 days of immersion while dicyclohexylamine nitrite and sodium benzoate treated specimens performed better than those treated with sodium dihydrogen orthophosphate. The objective of this research was to investigate the performances of three inhibitors - sodium dihydrogen orthophosphate (inorganic) at 10?mM concentration, dicyclohexylamine nitrite (organic) and sodium benzoate (organic) at 100?mM concentration - in controlling the corrosion of local mild steel products fully immersed in two test solutions, distilled water and the simulated salt solution. All three inhibitors are film forming and anodic type inhibitors. According to the authors' literature review, this study is original and will add value to the studies of inhibition of steel corrosion under similar environments.