Synergistic influence of iodide ions on the inhibition of corrosion of mild steel in sulphuric acid by cyclohexylamine

Abstract

<span style="font-size:11.0pt;font-family:" calibri","sans-serif";="" mso-ascii-theme-font:minor-latin;mso-fareast-font-family:"times="" new="" roman";="" mso-fareast-theme-font:minor-fareast;mso-hansi-theme-font:minor-latin;="" mso-bidi-font-family:"times="" roman";mso-ansi-language:en-us;mso-fareast-language:="" en-us;mso-bidi-language:ar-sa"="">The synergistic inhibition of corrosion of mild steel in 0.5 M H₂SO₄ by a combination of cyclohexylamint (CHA) and iodide ions has been studied using different electrochemical techniques. Corrosion inhibition is found to decrease with increase in the concentration of CHA. Iodide ions are found to enhance the inhibition by CHA considerably. Synergistic parameters such as S₁, and S_{<span style="font-size:11.0pt;font-family:" calibri","sans-serif";mso-ascii-theme-font:="" minor-latin;mso-fareast-font-family:"times="" new="" roman";mso-fareast-theme-font:="" minor-fareast;mso-hansi-theme-font:minor-latin;mso-bidi-theme-font:minor-latin;="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">θ</span>}<span style="font-size:11.0pt;font-family:" calibri","sans-serif";mso-ascii-theme-font:="" minor-latin;mso-fareast-font-family:"times="" new="" roman";mso-fareast-theme-font:="" minor-fareast;mso-hansi-theme-font:minor-latin;mso-bidi-font-family:"times="" roman";="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"=""> obtained from values of inhibition efficiency and surface coverage are found to be more than unity. This observation clearly shows the synergistic influence of iodide ions on the corrosion inhibition by CRA. The adsorption of CHA alone and in combination with iodide ions obeys Langmuir's adsorption isotherm.</span></span>